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Sample records for discrimination reversal learning

  1. Discrimination Reversal Learning in Capuchin Monkeys ("Cebus apella")

    Science.gov (United States)

    Beran, Michael J.; Klein, Emily D.; Evans, Theodore A.; Chan, Betty; Flemming, Timothy M.; Harris, Emily H.; Washburn, David A.; Rumbaugh, Duane M.

    2008-01-01

    Learning styles in capuchin monkeys were assessed with a computerized reversal-learning task called the mediational paradigm. First, monkeys were trained to respond with 90% accuracy on a two-choice discrimination (A+B-). Then the authors examined differences in performance on three different types of reversal trials (A-B+, A-C+, B+C-), each of…

  2. Post-training depletions of basolateral amygdala serotonin fail to disrupt discrimination, retention, or reversal learning.

    Science.gov (United States)

    Ochoa, Jesus G; Stolyarova, Alexandra; Kaur, Amandeep; Hart, Evan E; Bugarin, Amador; Izquierdo, Alicia

    2015-01-01

    In goal-directed pursuits, the basolateral amygdala (BLA) is critical in learning about changes in the value of rewards. BLA-lesioned rats show enhanced reversal learning, a task employed to measure the flexibility of response to changes in reward. Similarly, there is a trend for enhanced discrimination learning, suggesting that BLA may modulate formation of stimulus-reward associations. There is a parallel literature on the importance of serotonin (5HT) in new stimulus-reward and reversal learning. Recent postulations implicate 5HT in learning from punishment. Whereas, dopaminergic involvement is critical in behavioral activation and reinforcement, 5HT may be most critical for aversive processing and behavioral inhibition, complementary cognitive processes. Given these findings, a 5HT-mediated mechanism in BLA may mediate the facilitated learning observed previously. The present study investigated the effects of selective 5HT lesions in BLA using 5,7-dihydroxytryptamine (5,7-DHT) vs. infusions of saline (Sham) on discrimination, retention, and deterministic reversal learning. Rats were required to reach an 85% correct pairwise discrimination and single reversal criterion prior to surgery. Postoperatively, rats were then tested on the (1) retention of the pretreatment discrimination pair, (2) discrimination of a novel pair, and (3) reversal learning performance. We found statistically comparable preoperative learning rates between groups, intact postoperative retention, and unaltered novel discrimination and reversal learning in 5,7-DHT rats. These findings suggest that 5HT in BLA is not required for formation and flexible adjustment of new stimulus-reward associations when the strategy to efficiently solve the task has already been learned. Given the complementary role of orbitofrontal cortex in reward learning and its interconnectivity with BLA, these findings add to the list of dissociable mechanisms for BLA and orbitofrontal cortex in reward learning.

  3. Post-training depletions of basolateral amygdala serotonin fail to disrupt discrimination, retention, or reversal learning

    Directory of Open Access Journals (Sweden)

    G. Jesus eOchoa

    2015-05-01

    Full Text Available In goal-directed pursuits, the basolateral amygdala (BLA is critical in learning about changes in the value of rewards. BLA-lesioned rats show enhanced reversal learning, a task employed to measure the flexibility of response to changes in reward. Similarly, there is a trend for enhanced discrimination learning, suggesting that BLA may modulate formation of stimulus-reward associations. There is a parallel literature on the importance of serotonin (5HT in new stimulus-reward and reversal learning. Recent postulations implicate 5HT in learning from punishment. Whereas dopaminergic involvement is critical in behavioral activation and reinforcement, 5HT may be most critical for aversive processing and behavioral inhibition, complementary cognitive processes. Given these findings, a 5HT-mediated mechanism in BLA may mediate the facilitated learning observed previously. The present study investigated the effects of selective 5HT lesions in BLA using 5,7-dihydroxytryptamine (5,7-DHT versus infusions of saline (Sham on discrimination, retention, and deterministic reversal learning. Rats were required to reach an 85% correct pairwise discrimination and single reversal criterion prior to surgery. Postoperatively, rats were then tested on the 1 retention of the pretreatment discrimination pair 2 discrimination of a novel pair and 3 reversal learning performance. We found statistically comparable preoperative learning rates between groups, intact postoperative retention, and unaltered novel discrimination and reversal learning in 5,7-DHT rats. These findings suggest that 5HT in BLA is not required for formation and flexible adjustment of new stimulus-reward associations when the strategy to efficiently solve the task has already been learned. Given the complementary role of orbitofrontal cortex in reward learning and its interconnectivity with BLA, these findings add to the list of dissociable mechanisms for BLA and orbitofrontal cortex in reward learning.

  4. Post-training depletions of basolateral amygdala serotonin fail to disrupt discrimination, retention, or reversal learning

    OpenAIRE

    G. Jesus eOchoa; Alexandra eStolyarova; Amandeep eKaur; Evan eHart; Amador eBugarin; Alicia eIzquierdo

    2015-01-01

    In goal-directed pursuits, the basolateral amygdala (BLA) is critical in learning about changes in the value of rewards. BLA-lesioned rats show enhanced reversal learning, a task employed to measure the flexibility of response to changes in reward. Similarly, there is a trend for enhanced discrimination learning, suggesting that BLA may modulate formation of stimulus-reward associations. There is a parallel literature on the importance of serotonin (5HT) in new stimulus-reward and reversal le...

  5. Associative Encoding in Anterior Piriform Cortex versus Orbitofrontal Cortex during Odor Discrimination and Reversal Learning

    Science.gov (United States)

    Roesch, Matthew R.; Stalnaker, Thomas A.; Schoenbaum, Geoffrey

    2008-01-01

    Recent proposals have conceptualized piriform cortex as an association cortex, capable of integrating incoming olfactory information with descending input from higher order associative regions such as orbitofrontal cortex (OFC). If true, encoding in piriform cortex should reflect associative features prominent in these areas during associative learning involving olfactory cues. To test this hypothesis, we recorded from neurons in OFC and anatomically related parts of the anterior piriform cortex (APC) in rats, learning and reversing novel odor discriminations. Findings in OFC were similar to what we have reported previously, with nearly all the cue-selective neurons exhibiting substantial plasticity during learning and reversal. Also, many of the cue-selective neurons were originally responsive in anticipation of the outcomes early in learning, thereby providing a single-unit representation of the cue-outcome associations. Some of these features were also evident in firing activity in APC, including some plasticity across learning and reversal. However, APC neurons failed to reverse cue selectivity when the associated outcome was changed, and the cue-selective population did not include neurons that were active prior to outcome delivery. Thus, although representations in APC are substantially more associative than expected in a purely sensory region, they do appear to be somewhat more constrained by the sensory features of the odor cues than representations in downstream areas of OFC. PMID:16699083

  6. Reversing Discrimination: A Perspective

    Science.gov (United States)

    Pati, Gopal; Reilly, Charles W.

    1977-01-01

    Examines the debate over affirmative action and reverse discrimination, and discusses how and why the present dilemma has developed. Suggests that organizations can best address the problem through an honest, in-depth analysis of their organizational structure and management practices. (JG)

  7. Serial discrimination reversal learning in pigeons as a function of signal properties during the delay of reinforcement.

    Science.gov (United States)

    Ploog, Bertram O; Williams, Ben A

    2013-09-01

    Pigeons learned a series of reversals of a simultaneous red-green discrimination with a 6-s delay of reinforcement. The signal properties during the 6-s reinforcement delay were varied across blocks of reversals, such that the delay was either unsignaled (intertrial interval conditions during the delay) or signaled by illumination of the center key. Four different signal conditions were presented: (1) signals only after S+ responses, (2) signals only after S- responses, (3) differential signals after S+ versus S- responding, and (4) the same nondifferential signals after S+ and S- responses. (A zero-delay control condition was also included.) Learning was at a high level in the S+ -only and differential-signal conditions, and learning was at a low level during the unsignaled, nondifferentially signaled, and S- signal conditions. Thus, a differential stimulus contingent on correct choices was necessary for proficient learning-to-learn, even though within-reversal learning occurred in all conditions. During the S+ and differential-signal conditions, improvement in learning continued to occur even after more than 240 reversals (more than 38,000 trials).

  8. Stress facilitates late reversal learning using a touchscreen-based visual discrimination procedure in male Long Evans rats.

    Science.gov (United States)

    Bryce, Courtney A; Howland, John G

    2015-02-01

    The stress response is essential to the survival of all species as it maintains internal equilibrium and allows organisms to respond to threats in the environment. Most stress research has focused on the detrimental impacts of stress on cognition and behavior. Reversal learning, which requires a change in response strategy based on one dimension of the stimuli, is one type of behavioral flexibility that is facilitated following some brief stress procedures. The current study investigated a potential mechanism underlying this facilitation by blocking glucocorticoid receptors (GRs) during stress. Thirty-seven male Long Evans rats learned to discriminate between two images on a touchscreen, one of which was rewarded. Once a criterion was reached, rats received stress (30 min of restraint stress or no stress) and drug (GR antagonist RU38486 or vehicle) administration prior to each of the first 3 days of reversal learning. We expected that stress would facilitate reversal learning and RU38486 (10 mg/kg) would prevent this facilitation in both early (50% correct in one session) stages of reversal learning. Results showed that stressed rats performed better than unstressed rats (fewer days for late reversal, fewer correction trials, and fewer errors) in the late but not early stage of reversal learning. RU38486 did not block the facilitation of RL by stress, although it dramatically increased response, but not reward, latencies. These results confirm the facilitation of late reversal by stress in a touchscreen-based operant task in rats and further our understanding of how stress affects higher level cognitive functioning and behavior.

  9. Associative encoding in posterior piriform cortex during odor discrimination and reversal learning.

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    Calu, Donna J; Roesch, Matthew R; Stalnaker, Thomas A; Schoenbaum, Geoffrey

    2007-06-01

    Recent proposals have conceptualized piriform cortex as an association cortex, capable of integrating incoming olfactory information with descending input from higher order associative regions such as orbitofrontal cortex and basolateral amygdala (ABL). If true, encoding in piriform cortex should reflect associative features prominent in these areas during associative learning involving olfactory cues. We recently reported that neurons in anterior piriform cortex (APC) in rats exhibited significant plasticity in their responses to odor cues during associative learning. Here, we have repeated this study, recording from neurons in posterior piriform cortex (PPC), a region of piriform cortex that receives much stronger input from ABL. If associative encoding in piriform cortex is driven by inputs from ABL, then we should see more plasticity in PPC neurons than we observed in APC. Consistent with this hypothesis, we found that PPC neurons were highly associative and appeared to be somewhat more likely than neurons recorded in APC to alter their responses to the odor cues after reversal of the odor-outcome associations in the task. Further, odor-selective PPC populations exhibited markedly different firing patterns based on the valence of the odor cue. These results suggest associative encoding in piriform cortex is represented in a topographical fashion, reflecting the stronger and more specific input from olfactory bulb concerning the sensory features of odors in anterior regions and stronger input from ABL concerning the meaning of odors in posterior regions.

  10. Associative Encoding in Posterior Piriform Cortex during Odor Discrimination and Reversal Learning

    OpenAIRE

    Calu, Donna J.; Roesch, Matthew R.; Stalnaker, Thomas A; Schoenbaum, Geoffrey

    2006-01-01

    Recent proposals have conceptualized piriform cortex as an association cortex, capable of integrating incoming olfactory information with descending input from higher order associative regions such as orbitofrontal cortex and basolateral amygdala (ABL). If true, encoding in piriform cortex should reflect associative features prominent in these areas during associative learning involving olfactory cues. We recently reported that neurons in anterior piriform cortex (APC) in rats exhibited signi...

  11. Awake, long-term intranasal insulin treatment does not affect object memory, odor discrimination, or reversal learning in mice.

    Science.gov (United States)

    Bell, Genevieve A; Fadool, Debra Ann

    2017-05-15

    Intranasal insulin delivery is currently being used in clinical trials to test for improvement in human memory and cognition, and in particular, for lessening memory loss attributed to neurodegenerative diseases. Studies have reported the effects of short-term intranasal insulin treatment on various behaviors, but less have examined long-term effects. The olfactory bulb contains the highest density of insulin receptors in conjunction with the highest level of insulin transport within the brain. Previous research from our laboratory has demonstrated that acute insulin intranasal delivery (IND) enhanced both short- and long-term memory as well as increased two-odor discrimination in a two-choice paradigm. Herein, we investigated the behavioral and physiological effects of chronic insulin IND. Adult, male C57BL6/J mice were intranasally treated with 5μg/μl of insulin twice daily for 30 and 60days. Metabolic assessment indicated no change in body weight, caloric intake, or energy expenditure following chronic insulin IND, but an increase in the frequency of meal bouts selectively in the dark cycle. Unlike acute insulin IND, which has been shown to cause enhanced performance in odor habituation/dishabituation and two-odor discrimination tasks in mice, chronic insulin IND did not enhance olfactometry-based odorant discrimination or olfactory reversal learning. In an object memory recognition task, insulin IND-treated mice did not perform differently than controls, regardless of task duration. Biochemical analyses of the olfactory bulb revealed a modest 1.3 fold increase in IR kinase phosphorylation but no significant increase in Kv1.3 phosphorylation. Substrate phosphorylation of IR kinase downstream effectors (MAPK/ERK and Akt signaling) proved to be highly variable. These data indicate that chronic administration of insulin IND in mice fails to enhance olfactory ability, object memory recognition, or a majority of systems physiology metabolic factors - as reported to

  12. Hyperlipidemic diet causes loss of olfactory sensory neurons, reduces olfactory discrimination, and disrupts odor-reversal learning.

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    Thiebaud, Nicolas; Johnson, Melissa C; Butler, Jessica L; Bell, Genevieve A; Ferguson, Kassandra L; Fadool, Andrew R; Fadool, James C; Gale, Alana M; Gale, David S; Fadool, Debra A

    2014-05-14

    Currently, 65% of Americans are overweight, which leads to well-supported cardiovascular and cognitive declines. Little, however, is known concerning obesity's impact on sensory systems. Because olfaction is linked with ingestive behavior to guide food choice, its potential dysfunction during obesity could evoke a positive feedback loop to perpetuate poor ingestive behaviors. To determine the effect of chronic energy imbalance and reveal any structural or functional changes associated with obesity, we induced long-term, diet-induced obesity by challenging mice to high-fat diets: (1) in an obesity-prone (C57BL/6J) and obesity-resistant (Kv1.3(-/-)) line of mice, and compared this with (2) late-onset, genetic-induced obesity in MC4R(-/-) mice in which diabetes secondarily precipitates after disruption of the hypothalamic axis. We report marked loss of olfactory sensory neurons and their axonal projections after exposure to a fatty diet, with a concomitant reduction in electro-olfactogram amplitude. Loss of olfactory neurons and associated circuitry is linked to changes in neuronal proliferation and normal apoptotic cycles. Using a computer-controlled, liquid-based olfactometer, mice maintained on fatty diets learn reward-reinforced behaviors more slowly, have deficits in reversal learning demonstrating behavioral inflexibility, and exhibit reduced olfactory discrimination. When obese mice are removed from their high-fat diet to regain normal body weight and fasting glucose, olfactory dysfunctions are retained. We conclude that chronic energy imbalance therefore presents long-lasting structural and functional changes in the operation of the sensory system designed to encode external and internal chemical information and leads to altered olfactory- and reward-driven behaviors.

  13. Effects of subchronic phencyclidine (PCP treatment on social behaviors, and operant discrimination and reversal learning in C57BL/6J mice

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    Jonathan L Brigman

    2009-02-01

    Full Text Available Subchronic treatment with the psychotomimetic phencyclidine (PCP has been proposed as a rodent model of the negative and cognitive/executive symptoms of schizophrenia. There has, however, been a paucity of studies on this model in mice, despite the growing use of the mouse as a subject in genetic and molecular studies of schizophrenia. In the present study, we evaluated the effects of subchronic PCP treatment (5 mg/kg twice daily x 7 days, followed by 7 days withdrawal in C57BL/6J mice on 1 social behaviors using a sociability/social novelty-preference paradigm, and 2 pairwise visual discrimination and reversal learning using a touchscreen-based operant system. Results showed that mice subchronically treated with PCP made more visits to (but did not spend more time with a social stimulus relative to an inanimate one, and made more visits and spent more time investigating a novel social stimulus over a familiar one. Subchronic PCP treatment did not significantly affect behavior in either the discrimination or reversal learning tasks. These data encourage further analysis of the potential utility of mouse subchronic PCP treatment for modeling the social withdrawal component of schizophrenia. They also indicate that the treatment regimen employed was insufficient to impair our measures of discrimination and reversal learning in the C57BL/6J strain. Further work will be needed to identify alternative methods (e.g., repeated cycles of subchronic PCP treatment, use of different mouse strains that produce discrimination and/or reversal impairment, as well as other cognitive/executive measures that are sensitive to chronic PCP treatment in mice.

  14. Stress facilitates late reversal learning using a touchscreen-based visual discrimination procedure in male Long Evans rats

    OpenAIRE

    Bryce, Courtney A.; Howland, John G.

    2014-01-01

    The stress response is essential to the survival of all species as it maintains internal equilibrium and allows organisms to respond to threats in the environment. Most stress research has focused on the detrimental impacts of stress on cognition and behavior. Reversal learning, which requires a change in response strategy based on one dimension of the stimuli, is one type of behavioral flexibility that is facilitated following some brief stress procedures. The current study investigated a po...

  15. Discrimination Learning in Children

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    Ochocki, Thomas E.; And Others

    1975-01-01

    Examined the learning performance of 192 fourth-, fifth-, and sixth-grade children on either a two or four choice simultaneous color discrimination task. Compared the use of verbal reinforcement and/or punishment, under conditions of either complete or incomplete instructions. (Author/SDH)

  16. Discriminately Decreasing Discriminability with Learned Image Filters

    CERN Document Server

    Whitehill, Jacob

    2011-01-01

    In machine learning and computer vision, input images are often filtered to increase data discriminability. In some situations, however, one may wish to purposely decrease discriminability of one classification task (a "distractor" task), while simultaneously preserving information relevant to another (the task-of-interest): For example, it may be important to mask the identity of persons contained in face images before submitting them to a crowdsourcing site (e.g., Mechanical Turk) when labeling them for certain facial attributes. Another example is inter-dataset generalization: when training on a dataset with a particular covariance structure among multiple attributes, it may be useful to suppress one attribute while preserving another so that a trained classifier does not learn spurious correlations between attributes. In this paper we present an algorithm that finds optimal filters to give high discriminability to one task while simultaneously giving low discriminability to a distractor task. We present r...

  17. Multiple reversal olfactory learning in honeybees

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    Theo Mota

    2010-07-01

    Full Text Available In multiple reversal learning, animals trained to discriminate a reinforced from a non-reinforced stimulus are subjected to various, successive reversals of stimulus contingencies (e.g. A+ vs. B-, A- vs. B+, A+ vs. B-. This protocol is useful to determine whether or not animals learn to learn and solve successive discriminations faster (or with fewer errors with increasing reversal experience. Here we used the olfactory conditioning of proboscis extension reflex to study how honeybees Apis mellifera perform in a multiple reversal task. Our experiment contemplated four consecutive differential conditioning phases involving the same odors (A+ vs. B- to A- vs. B+ to A+ vs. B- to A- vs. B+. We show that bees in which the weight of reinforced or non-reinforced stimuli was similar mastered the multiple olfactory reversals. Bees which failed the task exhibited asymmetric responses to reinforced and non-reinforced stimuli, thus being unable to rapidly reverse stimulus contingencies. Efficient reversers did not improve their successive discriminations but rather tended to generalize their choice to both odors at the end of conditioning. As a consequence, both discrimination and reversal efficiency decreasedalong experimental phases. This result invalidates a learning-to-learn effect and indicates that bees do not only respond to the actual stimulus contingencies but rather combine these with an average of past experiences with the same stimuli.  

  18. Olfactory repeated discrimination reversal in rats: effects of chlordiazepoxide, dizocilpine, and morphine.

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    Galizio, Mark; Miller, Laurence; Ferguson, Adam; McKinney, Patrick; Pitts, Raymond C

    2006-10-01

    Effects of a benzodiazepine (chlordiazepoxide), an N-methyl-D-aspartate receptor antagonist (dizocilpine), and an opiate agonist (morphine) were studied with a procedure designed to assess effects of drugs and other manipulations on nonspatial learning in rats. In each session, rats were exposed to 2 different 2-choice odor-discrimination problems with food reinforcement for correct responses. One problem (performance discrimination) remained the same throughout the study. That is, 1 odor was always correct (S+) and the other was never correct (S-). For the other problem (reversal discrimination), stimuli changed every session. Six different odors were used to program the reversal discrimination; on any given session, S+ was a stimulus that had served as S- the last time it had appeared, S- was a stimulus that had been S+ on its last appearance. Thus, in each session, learning a discrimination reversal could be studied along with the performance of a comparable, but previously learned, discrimination. Chlordiazepoxide interfered with reversal learning at doses that had no effect on the performance discrimination. Morphine and dizocilpine also impaired reversal learning but only at doses that also affected performance of the well-learned performance discrimination.

  19. Discriminative learning for speech recognition

    CERN Document Server

    He, Xiadong

    2008-01-01

    In this book, we introduce the background and mainstream methods of probabilistic modeling and discriminative parameter optimization for speech recognition. The specific models treated in depth include the widely used exponential-family distributions and the hidden Markov model. A detailed study is presented on unifying the common objective functions for discriminative learning in speech recognition, namely maximum mutual information (MMI), minimum classification error, and minimum phone/word error. The unification is presented, with rigorous mathematical analysis, in a common rational-functio

  20. Learning to Discriminate Face Views

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    Fang Fang

    2011-05-01

    Full Text Available Although visual feature leaning has been well studied, we still know little about the mechanisms of perceptual learning of complex object. Here, human perceptual learning in discrimination of in-depth orientation of face view was studied using psychophysics, EEG and fMRI. We trained subjects to discriminate face orientations around a face view (i.e. 30° over eight daily sessions, which resulted in a significant improvement in sensitivity to the face view orientation. This improved sensitivity was highly specific to the trained orientation and persisted up to six months. Different from perceptual learning of simple visual features, this orientation-specific learning effect could completely transfer across changes in face size, visual field and face identity. A complete transfer also occurred between two partial face images that were mutually exclusive but constituted a complete face. However, the transfer of the learning effect between upright and inverted faces and between a face and a paperclip object was very weak. Before and after training, we measured EEG and fMRI BOLD signals responding to both the trained and the untrained face views. Analyses of ERPs and induced gamma activity showed that face view discrimination training led to a larger reduction of N170 latency at the left occipital-temporal area and a concurrent larger decrease of induced gamma activity at the left frontal area with the trained face view, compared with the untrained ones. BOLD signal amplitude and MVPA analyses showed that, in face-selective cortical areas, training did not lead to a significant amplitude change, but induced a more reliable spatial pattern of neural activity in the left FFA. These results suggest that the visual system had learned how to compute face orientation from face configural information more accurately and that a large amount of plastic changes took place at a level of higher visual processing where size-, location-, and identity

  1. Stimulus discriminability may bias value-based probabilistic learning

    Science.gov (United States)

    Slagter, Heleen A.; Collins, Anne G. E.; Frank, Michael J.; Kenemans, J. Leon

    2017-01-01

    Reinforcement learning tasks are often used to assess participants’ tendency to learn more from the positive or more from the negative consequences of one’s action. However, this assessment often requires comparison in learning performance across different task conditions, which may differ in the relative salience or discriminability of the stimuli associated with more and less rewarding outcomes, respectively. To address this issue, in a first set of studies, participants were subjected to two versions of a common probabilistic learning task. The two versions differed with respect to the stimulus (Hiragana) characters associated with reward probability. The assignment of character to reward probability was fixed within version but reversed between versions. We found that performance was highly influenced by task version, which could be explained by the relative perceptual discriminability of characters assigned to high or low reward probabilities, as assessed by a separate discrimination experiment. Participants were more reliable in selecting rewarding characters that were more discriminable, leading to differences in learning curves and their sensitivity to reward probability. This difference in experienced reinforcement history was accompanied by performance biases in a test phase assessing ability to learn from positive vs. negative outcomes. In a subsequent large-scale web-based experiment, this impact of task version on learning and test measures was replicated and extended. Collectively, these findings imply a key role for perceptual factors in guiding reward learning and underscore the need to control stimulus discriminability when making inferences about individual differences in reinforcement learning. PMID:28481915

  2. Stimulus discriminability may bias value-based probabilistic learning.

    Science.gov (United States)

    Schutte, Iris; Slagter, Heleen A; Collins, Anne G E; Frank, Michael J; Kenemans, J Leon

    2017-01-01

    Reinforcement learning tasks are often used to assess participants' tendency to learn more from the positive or more from the negative consequences of one's action. However, this assessment often requires comparison in learning performance across different task conditions, which may differ in the relative salience or discriminability of the stimuli associated with more and less rewarding outcomes, respectively. To address this issue, in a first set of studies, participants were subjected to two versions of a common probabilistic learning task. The two versions differed with respect to the stimulus (Hiragana) characters associated with reward probability. The assignment of character to reward probability was fixed within version but reversed between versions. We found that performance was highly influenced by task version, which could be explained by the relative perceptual discriminability of characters assigned to high or low reward probabilities, as assessed by a separate discrimination experiment. Participants were more reliable in selecting rewarding characters that were more discriminable, leading to differences in learning curves and their sensitivity to reward probability. This difference in experienced reinforcement history was accompanied by performance biases in a test phase assessing ability to learn from positive vs. negative outcomes. In a subsequent large-scale web-based experiment, this impact of task version on learning and test measures was replicated and extended. Collectively, these findings imply a key role for perceptual factors in guiding reward learning and underscore the need to control stimulus discriminability when making inferences about individual differences in reinforcement learning.

  3. Discrimination learning in adult bobwhite quail fed paraquat

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    Bunck, C.M.; Bunck, T.J.; Sileo, L.

    1986-01-01

    Adult male bobwhite quail (Colinus virginianus) were fed a diet containing 0, 25 or 100 ppm paraquat dichloride. After 60 d on treated diets, discrimination learning was evaluated with acquisition and reversal tests. The three groups performed similarly on these tests. Dose-related histopathological lesions were not found in liver, kidney or lung tissues

  4. Discrimination of mixed quantum states. Reversible maps and unambiguous strategies

    Energy Technology Data Exchange (ETDEWEB)

    Kleinmann, Matthias

    2008-06-30

    commutators and allows an explicit construction of the (2 x 2)-dimensional blocks. As an important application of unambiguous state discrimination, unambiguous state comparison, i.e., the question whether two states are identical or not, is generalized and optimal measurements for this problem are constructed. If for a certain family of states, a physical device maps the input state to an output state, such that a second device can be built that yields back the original input state, such a map is called reversible on this family. With respect to state discrimination, such reversible maps are particularly interesting, if the output states are pure. A complete characterization of all families that allow such a reversible and purifying map is provided. If the states are mapped to pure states, but the map itself is not reversible, upper and lower bounds are analyzed for the ''deviation from perfect faithfulness'', a quantity which measures the deviation from a reversible mapping. (orig.)

  5. Discriminative Structured Dictionary Learning for Image Classification

    Institute of Scientific and Technical Information of China (English)

    王萍; 兰俊花; 臧玉卫; 宋占杰

    2016-01-01

    In this paper, a discriminative structured dictionary learning algorithm is presented. To enhance the dictionary’s discriminative power, the reconstruction error, classification error and inhomogeneous representation error are integrated into the objective function. The proposed approach learns a single structured dictionary and a linear classifier jointly. The learned dictionary encourages the samples from the same class to have similar sparse codes, and the samples from different classes to have dissimilar sparse codes. The solution to the objective function is achieved by employing a feature-sign search algorithm and Lagrange dual method. Experimental results on three public databases demonstrate that the proposed approach outperforms several recently proposed dictionary learning techniques for classification.

  6. Auditory Discrimination Learning: Role of Working Memory.

    Directory of Open Access Journals (Sweden)

    Yu-Xuan Zhang

    Full Text Available Perceptual training is generally assumed to improve perception by modifying the encoding or decoding of sensory information. However, this assumption is incompatible with recent demonstrations that transfer of learning can be enhanced by across-trial variation of training stimuli or task. Here we present three lines of evidence from healthy adults in support of the idea that the enhanced transfer of auditory discrimination learning is mediated by working memory (WM. First, the ability to discriminate small differences in tone frequency or duration was correlated with WM measured with a tone n-back task. Second, training frequency discrimination around a variable frequency transferred to and from WM learning, but training around a fixed frequency did not. The transfer of learning in both directions was correlated with a reduction of the influence of stimulus variation in the discrimination task, linking WM and its improvement to across-trial stimulus interaction in auditory discrimination. Third, while WM training transferred broadly to other WM and auditory discrimination tasks, variable-frequency training on duration discrimination did not improve WM, indicating that stimulus variation challenges and trains WM only if the task demands stimulus updating in the varied dimension. The results provide empirical evidence as well as a theoretic framework for interactions between cognitive and sensory plasticity during perceptual experience.

  7. Unifying generative and discriminative learning principles

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    Strickert Marc

    2010-02-01

    Full Text Available Abstract Background The recognition of functional binding sites in genomic DNA remains one of the fundamental challenges of genome research. During the last decades, a plethora of different and well-adapted models has been developed, but only little attention has been payed to the development of different and similarly well-adapted learning principles. Only recently it was noticed that discriminative learning principles can be superior over generative ones in diverse bioinformatics applications, too. Results Here, we propose a generalization of generative and discriminative learning principles containing the maximum likelihood, maximum a posteriori, maximum conditional likelihood, maximum supervised posterior, generative-discriminative trade-off, and penalized generative-discriminative trade-off learning principles as special cases, and we illustrate its efficacy for the recognition of vertebrate transcription factor binding sites. Conclusions We find that the proposed learning principle helps to improve the recognition of transcription factor binding sites, enabling better computational approaches for extracting as much information as possible from valuable wet-lab data. We make all implementations available in the open-source library Jstacs so that this learning principle can be easily applied to other classification problems in the field of genome and epigenome analysis.

  8. Two-item discrimination and Hamilton search learning in infant pigtailed macaque monkeys

    NARCIS (Netherlands)

    Ha, J.C.; Mandell, D.J.; Gray, J.

    2011-01-01

    This study investigated how infant pigtailed macaque monkeys performed on two separate learning assessments, two-object discrimination/reversal and Hamilton search learning. Although the learning tasks have been tested on several species, including non-human primates, there have been no normative

  9. Two-item discrimination and Hamilton search learning in infant pigtailed macaque monkeys

    NARCIS (Netherlands)

    Ha, J.C.; Mandell, D.J.; Gray, J.

    2011-01-01

    This study investigated how infant pigtailed macaque monkeys performed on two separate learning assessments, two-object discrimination/reversal and Hamilton search learning. Although the learning tasks have been tested on several species, including non-human primates, there have been no normative re

  10. Discriminative learning for dynamic state prediction.

    Science.gov (United States)

    Kim, Minyoung; Pavlovic, Vladimir

    2009-10-01

    We consider the problem of predicting a sequence of real-valued multivariate states that are correlated by some unknown dynamics, from a given measurement sequence. Although dynamic systems such as the State-Space Models are popular probabilistic models for the problem, their joint modeling of states and observations, as well as the traditional generative learning by maximizing a joint likelihood may not be optimal for the ultimate prediction goal. In this paper, we suggest two novel discriminative approaches to the dynamic state prediction: 1) learning generative state-space models with discriminative objectives and 2) developing an undirected conditional model. These approaches are motivated by the success of recent discriminative approaches to the structured output classification in discrete-state domains, namely, discriminative training of Hidden Markov Models and Conditional Random Fields (CRFs). Extending CRFs to real multivariate state domains generally entails imposing density integrability constraints on the CRF parameter space, which can make the parameter learning difficult. We introduce an efficient convex learning algorithm to handle this task. Experiments on several problem domains, including human motion and robot-arm state estimation, indicate that the proposed approaches yield high prediction accuracy comparable to or better than state-of-the-art methods.

  11. Learning discriminative dictionary for group sparse representation.

    Science.gov (United States)

    Sun, Yubao; Liu, Qingshan; Tang, Jinhui; Tao, Dacheng

    2014-09-01

    In recent years, sparse representation has been widely used in object recognition applications. How to learn the dictionary is a key issue to sparse representation. A popular method is to use l1 norm as the sparsity measurement of representation coefficients for dictionary learning. However, the l1 norm treats each atom in the dictionary independently, so the learned dictionary cannot well capture the multisubspaces structural information of the data. In addition, the learned subdictionary for each class usually shares some common atoms, which weakens the discriminative ability of the reconstruction error of each subdictionary. This paper presents a new dictionary learning model to improve sparse representation for image classification, which targets at learning a class-specific subdictionary for each class and a common subdictionary shared by all classes. The model is composed of a discriminative fidelity, a weighted group sparse constraint, and a subdictionary incoherence term. The discriminative fidelity encourages each class-specific subdictionary to sparsely represent the samples in the corresponding class. The weighted group sparse constraint term aims at capturing the structural information of the data. The subdictionary incoherence term is to make all subdictionaries independent as much as possible. Because the common subdictionary represents features shared by all classes, we only use the reconstruction error of each class-specific subdictionary for classification. Extensive experiments are conducted on several public image databases, and the experimental results demonstrate the power of the proposed method, compared with the state-of-the-arts.

  12. Neural correlates of face gender discrimination learning.

    Science.gov (United States)

    Su, Junzhu; Tan, Qingleng; Fang, Fang

    2013-04-01

    Using combined psychophysics and event-related potentials (ERPs), we investigated the effect of perceptual learning on face gender discrimination and probe the neural correlates of the learning effect. Human subjects were trained to perform a gender discrimination task with male or female faces. Before and after training, they were tested with the trained faces and other faces with the same and opposite genders. ERPs responding to these faces were recorded. Psychophysical results showed that training significantly improved subjects' discrimination performance and the improvement was specific to the trained gender, as well as to the trained identities. The training effect indicates that learning occurs at two levels-the category level (gender) and the exemplar level (identity). ERP analyses showed that the gender and identity learning was associated with the N170 latency reduction at the left occipital-temporal area and the N170 amplitude reduction at the right occipital-temporal area, respectively. These findings provide evidence for the facilitation model and the sharpening model on neuronal plasticity from visual experience, suggesting a faster processing speed and a sparser representation of face induced by perceptual learning.

  13. Imbalanced Learning Based on Logistic Discrimination

    Directory of Open Access Journals (Sweden)

    Huaping Guo

    2016-01-01

    Full Text Available In recent years, imbalanced learning problem has attracted more and more attentions from both academia and industry, and the problem is concerned with the performance of learning algorithms in the presence of data with severe class distribution skews. In this paper, we apply the well-known statistical model logistic discrimination to this problem and propose a novel method to improve its performance. To fully consider the class imbalance, we design a new cost function which takes into account the accuracies of both positive class and negative class as well as the precision of positive class. Unlike traditional logistic discrimination, the proposed method learns its parameters by maximizing the proposed cost function. Experimental results show that, compared with other state-of-the-art methods, the proposed one shows significantly better performance on measures of recall, g-mean, f-measure, AUC, and accuracy.

  14. Reconsideration of Serial Visual Reversal Learning in Octopus (Octopus vulgaris) from a Methodological Perspective

    Science.gov (United States)

    Bublitz, Alexander; Weinhold, Severine R.; Strobel, Sophia; Dehnhardt, Guido; Hanke, Frederike D.

    2017-01-01

    Octopuses (Octopus vulgaris) are generally considered to possess extraordinary cognitive abilities including the ability to successfully perform in a serial reversal learning task. During reversal learning, an animal is presented with a discrimination problem and after reaching a learning criterion, the signs of the stimuli are reversed: the former positive becomes the negative stimulus and vice versa. If an animal improves its performance over reversals, it is ascribed advanced cognitive abilities. Reversal learning has been tested in octopus in a number of studies. However, the experimental procedures adopted in these studies involved pre-training on the new positive stimulus after a reversal, strong negative reinforcement or might have enabled secondary cueing by the experimenter. These procedures could have all affected the outcome of reversal learning. Thus, in this study, serial visual reversal learning was revisited in octopus. We trained four common octopuses (O. vulgaris) to discriminate between 2-dimensional stimuli presented on a monitor in a simultaneous visual discrimination task and reversed the signs of the stimuli each time the animals reached the learning criterion of ≥80% in two consecutive sessions. The animals were trained using operant conditioning techniques including a secondary reinforcer, a rod that was pushed up and down the feeding tube, which signaled the correctness of a response and preceded the subsequent primary reinforcement of food. The experimental protocol did not involve negative reinforcement. One animal completed four reversals and showed progressive improvement, i.e., it decreased its errors to criterion the more reversals it experienced. This animal developed a generalized response strategy. In contrast, another animal completed only one reversal, whereas two animals did not learn to reverse during the first reversal. In conclusion, some octopus individuals can learn to reverse in a visual task demonstrating behavioral

  15. Discriminative Bayesian Dictionary Learning for Classification.

    Science.gov (United States)

    Akhtar, Naveed; Shafait, Faisal; Mian, Ajmal

    2016-12-01

    We propose a Bayesian approach to learn discriminative dictionaries for sparse representation of data. The proposed approach infers probability distributions over the atoms of a discriminative dictionary using a finite approximation of Beta Process. It also computes sets of Bernoulli distributions that associate class labels to the learned dictionary atoms. This association signifies the selection probabilities of the dictionary atoms in the expansion of class-specific data. Furthermore, the non-parametric character of the proposed approach allows it to infer the correct size of the dictionary. We exploit the aforementioned Bernoulli distributions in separately learning a linear classifier. The classifier uses the same hierarchical Bayesian model as the dictionary, which we present along the analytical inference solution for Gibbs sampling. For classification, a test instance is first sparsely encoded over the learned dictionary and the codes are fed to the classifier. We performed experiments for face and action recognition; and object and scene-category classification using five public datasets and compared the results with state-of-the-art discriminative sparse representation approaches. Experiments show that the proposed Bayesian approach consistently outperforms the existing approaches.

  16. The nature of discrimination learning in pigeons.

    Science.gov (United States)

    Pearce, John M; Esber, Guillem R; George, David N; Haselgrove, Mark

    2008-08-01

    The results from five experiments are considered in relation to two of Spence's (1937, 1938) proposals concerning discrimination learning. In Experiments 1 and 2, we investigated whether his ideas about the interaction between excitatory and inhibitory generalization gradients can be used to understand how animals solve a complex patterning discrimination. The results supported a development of his proposals as put forward by Pearce (1994), provided a modification was made to Pearce's rulefor determining the shape ofthe generalization gradient. In Experiments 3, 4, and 5, we examined whether animals would pay more attention to stimuli that are relevant, rather than irrelevant, to the solution of a discrimination. The results supported this proposal for stimuli comprising visual patterns, but not for those comprising plain colors. The results also indicated that change of attention was a consequence of preliminary receptor-exposure acts, as envisaged by Spence, and not of more central changes in attention.

  17. Orientation specificity of learning vernier discriminations.

    Science.gov (United States)

    Spang, K; Grimsen, C; Herzog, M H; Fahle, M

    2010-02-22

    Orientation selective neurons in the primary visual cortex typically respond to a range of orientations that covers 20 degrees or more, while in psychophysical experiments, orientation bandwidth is often clearly narrower. Here, we measure the orientation specificity of perceptual learning for vernier discriminations. More than 70 observers, in separate groups, practiced a vernier discrimination task with a constant stimulus orientation. After a 1h session of training, the vernier was rotated by 2 degrees, 4 degrees, 10 degrees, 20 degrees, 45 degrees or 90 degrees. Improvement through training in the first session transferred to the second session (tested on the next day) up to 10 degrees of stimulus rotation. We found no transfer for rotations of 20 degrees, 45 degrees and 90 degrees. Hence, the orientation half-bandwidth of perceptual learning is around 15 degrees, leading to a bandwidth of 30 degrees and corresponding to that of single neurons in early visual cortices, while being narrower than that in higher cortical areas.

  18. Reversal learning enhanced by lysergic acid diethylamide (LSD)

    Science.gov (United States)

    King, A.R.; Martin, I.L.; Arabella Melville, K.

    1974-01-01

    1 Small doses of lysergic acid diethylamide (LSD) (12.5-50 μg/kg) consistently facilitated learning of a brightness discrimination reversal. 2 2-Bromo-lysergic acid diethylamide (BOL-148), a structural analogue of LSD, with similar peripheral anti-5-hydroxytrypamine activity but no psychotomimetic properties, had no effect in this learning situation at a similar dose (25 μg/kg). 3 LSD, but not BOL-148, caused a small but significant increase in brain 5-hydroxytryptamine levels, but had no effect on the levels of catecholamines in the brain at 25 μg/kg. PMID:4458849

  19. Characterization of the role of adult neurogenesis in touch-screen discrimination learning.

    Science.gov (United States)

    Swan, Alicia A; Clutton, Jonathan Edward; Chary, Priyanka Kesavan; Cook, Sarah G; Liu, Grace G; Drew, Michael R

    2014-12-01

    Recent theories posit that adult neurogenesis supports dentate gyrus pattern separation and hence is necessary for some types of discrimination learning. Using an inducible transgenic mouse model, we investigated the contribution of adult-born neurons to spatial and nonspatial touch-screen discriminations of varying levels of difficulty. Arresting neurogenesis caused a modest but statistically significant impairment in a position discrimination task. However, the effect was present only on trials after a learned discrimination was reversed, suggesting that neurogenesis supports cognitive flexibility rather than spatial discrimination per se. The deficit was present 4-10 weeks after the arrest of neurogenesis but not immediately after, consistent with previous evidence that the behavioral effects of arresting neurogenesis arise because of the depletion of adult-born neurons at least 1 month old. The arrest of neurogenesis failed to affect a nonspatial brightness discrimination task that was equal in difficulty to the spatial task. The data suggest that adult neurogenesis is not strictly necessary for spatial or perceptual discrimination learning and instead implicate adult neurogenesis in factors related to reversal learning, such as cognitive flexibility or proactive interference.

  20. Reverse hypothesis machine learning a practitioner's perspective

    CERN Document Server

    Kulkarni, Parag

    2017-01-01

    This book introduces a paradigm of reverse hypothesis machines (RHM), focusing on knowledge innovation and machine learning. Knowledge- acquisition -based learning is constrained by large volumes of data and is time consuming. Hence Knowledge innovation based learning is the need of time. Since under-learning results in cognitive inabilities and over-learning compromises freedom, there is need for optimal machine learning. All existing learning techniques rely on mapping input and output and establishing mathematical relationships between them. Though methods change the paradigm remains the same—the forward hypothesis machine paradigm, which tries to minimize uncertainty. The RHM, on the other hand, makes use of uncertainty for creative learning. The approach uses limited data to help identify new and surprising solutions. It focuses on improving learnability, unlike traditional approaches, which focus on accuracy. The book is useful as a reference book for machine learning researchers and professionals as ...

  1. Orientation During Initial Learning and Subsequent Discrimination of Faces

    Science.gov (United States)

    Cohen, Malcolm M.; Holton, Emily M. (Technical Monitor)

    1997-01-01

    Discrimination of facial features degrades with stimulus rotation (e.g., the "Margaret Thatcher" effect). Thirty-two observers learned to discriminate between two upright, or two inverted, faces. Images, erect and rotated by +/-45deg, +/-90deg, +/-135deg and 180deg about the line of sight, were presented on a computer screen. Initial discriminative reaction times increased with stimulus rotation only for observers who learned the upright faces. Orientation during learning is critical in identifying faces subsequently seen at different orientations.

  2. A Probe Trial Procedure for the Study of Children's Discrimination Learning and Transfer

    Science.gov (United States)

    Cole, Michael

    1976-01-01

    A discrimination reversal problem was presented to 192 children varying in age from 3 to 5 years. At the end of both the initial learning and transfer trials, probe trials were introduced to ascertain the response rule describing children's choices. (Author/SB)

  3. Active Discriminative Dictionary Learning for Weather Recognition

    Directory of Open Access Journals (Sweden)

    Caixia Zheng

    2016-01-01

    Full Text Available Weather recognition based on outdoor images is a brand-new and challenging subject, which is widely required in many fields. This paper presents a novel framework for recognizing different weather conditions. Compared with other algorithms, the proposed method possesses the following advantages. Firstly, our method extracts both visual appearance features of the sky region and physical characteristics features of the nonsky region in images. Thus, the extracted features are more comprehensive than some of the existing methods in which only the features of sky region are considered. Secondly, unlike other methods which used the traditional classifiers (e.g., SVM and K-NN, we use discriminative dictionary learning as the classification model for weather, which could address the limitations of previous works. Moreover, the active learning procedure is introduced into dictionary learning to avoid requiring a large number of labeled samples to train the classification model for achieving good performance of weather recognition. Experiments and comparisons are performed on two datasets to verify the effectiveness of the proposed method.

  4. Employer Learning and Statistical Discrimination. National Longitudinal Surveys Discussion Paper.

    Science.gov (United States)

    Altonji, Joseph G.; Pierret, Charles R.

    The relationship between employer learning and statistical discrimination was explored through a statistical analysis that included a test for statistical discrimination or "rational" stereotyping in environments where agents learn over time. The test is used to study the working hypothesis that, because firms have only limited information about…

  5. Reversal learning as a measure of impulsive and compulsive behavior in addictions.

    Science.gov (United States)

    Izquierdo, Alicia; Jentsch, J David

    2012-01-01

    Our ability to measure the cognitive components of complex decision-making across species has greatly facilitated our understanding of its neurobiological mechanisms. One task in particular, reversal learning, has proven valuable in assessing the inhibitory processes that are central to executive control. Reversal learning measures the ability to actively suppress reward-related responding and to disengage from ongoing behavior, phenomena that are biologically and descriptively related to impulsivity and compulsivity. Consequently, reversal learning could index vulnerability for disorders characterized by impulsivity such as proclivity for initial substance abuse as well as the compulsive aspects of dependence. Though we describe common variants and similar tasks, we pay particular attention to discrimination reversal learning, its supporting neural circuitry, neuropharmacology and genetic determinants. We also review the utility of this task in measuring impulsivity and compulsivity in addictions. We restrict our review to instrumental, reward-related reversal learning studies as they are most germane to addiction. The research reviewed here suggests that discrimination reversal learning may be used as a diagnostic tool for investigating the neural mechanisms that mediate impulsive and compulsive aspects of pathological reward-seeking and -taking behaviors. Two interrelated mechanisms are posited for the neuroadaptations in addiction that often translate to poor reversal learning: frontocorticostriatal circuitry dysregulation and poor dopamine (D2 receptor) modulation of this circuitry. These data suggest new approaches to targeting inhibitory control mechanisms in addictions.

  6. Generative and discriminative learning by CL-Net.

    Science.gov (United States)

    Sun, Yanmin; Wong, Andrew K C; Wang, Yang

    2007-08-01

    This correspondence presents a two-stage classification learning algorithm. The first stage approximates the class-conditional distribution of a discrete space using a separate mixture model, and the second stage investigates the class posterior probabilities by training a network. The first stage explores the generative information that is inherent in each class by using the Chow-Liu (CL) method, which approximates high-dimensional probability with a tree structure, namely, a dependence tree, whereas the second stage concentrates on discriminative learning to distinguish between classes. The resulting learning algorithm integrates the advantages of both generative learning and discriminative learning. Because it uses CL dependence-tree estimation, we call our algorithm CL-Net. Empirical tests indicate that the proposed learning algorithm makes significant improvements when compared with the related classifiers that are constructed by either generative learning or discriminative learning.

  7. Evaluation of the Artificial Neural Network for Color Discrimination : Discrimination of Non-learned Colors

    OpenAIRE

    Tayagaki, Yasuko; Sekiya, Satoko; Sekine, Seishi; Ohkawa, Masashi

    2004-01-01

    Our research purpose is to build an artificial neural network with an excellent color discrimination capability like human being on a computer. In this study, we built the network, which was trained to learn 10 colors with different hues in the Munsell color system. Then, we examined the response of the trained network when the network was interrogated about 10 non-learned colors. The network showed a good color discrimination capability, close to that of human being.

  8. An ART neural network model of discrimination shift learning

    NARCIS (Netherlands)

    Raijmakers, M.E.J.; Coffey, E.; Stevenson, C.; Winkel, J.; Berkeljon, A.; Taatgen, N.; van Rijn, H.

    2009-01-01

    We present an ART-based neural network model (adapted from [2]) of the development of discrimination-shift learning that models the trial-by-trial learning process in great detail. In agreement with the results of human participants (4-20 years of age) in [1] the model revealed two distinct learning

  9. MR PROSTATE SEGMENTATION VIA DISTRIBUTED DISCRIMINATIVE DICTIONARY (DDD) LEARNING.

    Science.gov (United States)

    Guo, Yanrong; Zhan, Yiqiang; Gao, Yaozong; Jiang, Jianguo; Shen, Dinggang

    2013-01-01

    Segmenting prostate from MR images is important yet challenging. Due to non-Gaussian distribution of prostate appearances in MR images, the popular active appearance model (AAM) has its limited performance. Although the newly developed sparse dictionary learning method[1, 2] can model the image appearance in a non-parametric fashion, the learned dictionaries still lack the discriminative power between prostate and non-prostate tissues, which is critical for accurate prostate segmentation. In this paper, we propose to integrate deformable model with a novel learning scheme, namely the Distributed Discriminative Dictionary (DDD) learning, which can capture image appearance in a non-parametric and discriminative fashion. In particular, three strategies are designed to boost the tissue discriminative power of DDD. First, minimum Redundancy Maximum Relevance (mRMR) feature selection is performed to constrain the dictionary learning in a discriminative feature space. Second, linear discriminant analysis (LDA) is employed to assemble residuals from different dictionaries for optimal separation between prostate and non-prostate tissues. Third, instead of learning the global dictionaries, we learn a set of local dictionaries for the local regions (each with small appearance variations) along prostate boundary, thus achieving better tissue differentiation locally. In the application stage, DDDs will provide the appearance cues to robustly drive the deformable model onto the prostate boundary. Experiments on 50 MR prostate images show that our method can yield a Dice Ratio of 88% compared to the manual segmentations, and have 7% improvement over the conventional AAM.

  10. The effect of excitotoxic hippocampal lesions on simple and conditional discrimination learning in the rat.

    Science.gov (United States)

    Murray, T K; Ridley, R M

    1999-02-15

    The effect of excitotoxic lesions of the hippocampus on acquisition and reversal of simple and conditional tasks was investigated using a Y-maze. Hippocampal-lesioned rats were severely impaired on acquisition and reversal of a conditional visuo-spatial task (where different pairs of visually distinctive choice arms indicated whether a left or right arm choice was correct on that trial) and were unable to acquire a visuo-visual conditional discrimination (where the appearance of the start arm indicated which of the visually distinctive choice arms was correct irrespective of their left/right position). They were not impaired on acquisition or reversal of a simple spatial left/right discrimination task (where all arms had the same visual appearance) nor on acquisition of a visual discrimination (where the correct, visually distinctive, choice arm varied in its left/right position). Hippocampal-lesioned rats were, however, impaired on reversal of this visual discrimination task and on acquisition and reversal of another visual discrimination task in which the visually distinctive choice arms were less different from each other than in the first version of this task. The degree of impairment in the lesioned rats was related to task difficulty for the sham-operated rats and was not specific to tasks requiring spatial choices, visual discrimination or conditional responding. The impairment on conditional tasks was greater than the impairment on those non-conditional tasks which happened to be matched for task difficulty for the sham-operated rats, suggesting that the conditional demand may target the function of the hippocampus rather closely. Statistically worse than chance performance by hippocampal-lesioned (and sham-operated) rats at the beginning of reversal testing, which was given 24 h after achieving criterion on acquisition of that task, indicated that hippocampal-lesioned rats simultaneously exhibited good memory but impaired learning for the type of

  11. Visual discrimination learning with an iPad-equipped apparatus.

    Science.gov (United States)

    Leising, Kenneth J; Wolf, Joshua E; Ruprecht, Chad M

    2013-02-01

    Visual discrimination tasks are commonly used to assess visual learning and memory in non-human animals. The current experiments explored the suitability of an iPad (Apple, Cupertino, California), as a low-cost alternative touchscreen for visual discrimination tasks. In Experiment 1, rats were trained with patterned black-and-white stimuli in a successive non-match to sample procedure. Rats successfully interacted with the iPad but failed to learn to withhold responding on trials in which the sample matched the comparison. Experiment 2 used the same patterned stimuli, but the procedure was simplified to a successive discrimination procedure and we explored the use of procedures known to facilitate discrimination learning. Rats that received training with differential outcomes and a differential reinforcement of other behavior schedule successfully acquired the task. In Experiment 3, the same rats were tested in a simultaneous discrimination task and we explored the use of a correction and non-correction method during acquisition. Rats that failed to learn the discrimination in the previous experiment, improved while trained with the correction method. These experiments support the use of the iPad in visual discrimination tasks and inform future studies investigating learning and memory within a touchscreen-equipped (iPad or other) apparatus.

  12. Effects of Dexamphetamine and Music on Reversal Learning.

    Science.gov (United States)

    Yazdani, Farzane; Naghshvarian, Mojtaba; Salehi, Alireza; Marzban, Maryam

    2016-03-01

    Reversal learning has proven to be a valuable task in assessing the inhibitory process that is central to executive control. Psycho-stimulants and music are prevalent factors that influence cognition. The present study aimed at investigating the influences of dexamphetamine and music on inhibitory control. This experimental study was conducted between May and June 2014 in the laboratory animal center of Shiraz University of Medical Sciences, Shiraz, Iran. Thirty mice were divided to five groups including a control group, a witness group, and three experimental groups. Food availability was restricted in order to maintain the subjects at 85% of their free-feeding body weight for behavioral testing. After discrimination learning, animals received four injections of 2 mg/kg dexamphetamine at two-hour intervals. The music group was exposed to music half an hour before reversal learning. According to the results of the repeated measure analysis of variance (ANOVA), music increased errors (mean difference: -2.40, 95% CI: -3.59 to -1.22), yet dexamphetamine had no significant effect on reversal learning. Due to various advantages, we transited to the mixed model that showed increasing (Beta: 2.2 95% CI: 0.26 to 4.13) and borderline (Beta: 1.8 95% CI: -0.13 to 3.73) effects on the number of errors for dexamphetamine and music group, respectively. Drug-treated subjects were impaired in their ability to modulate behavior, based upon changing information about stimulus-reward associations, possibly due to the inability to inhibit their response. These effects may have relevance to some mental disorders such as drug-abuse, schizophrenia, and obsessive-compulsive disorder.

  13. Unsupervised Spike Sorting Based on Discriminative Subspace Learning

    CERN Document Server

    Keshtkaran, Mohammad Reza

    2014-01-01

    Spike sorting is a fundamental preprocessing step for many neuroscience studies which rely on the analysis of spike trains. In this paper, we present two unsupervised spike sorting algorithms based on discriminative subspace learning. The first algorithm simultaneously learns the discriminative feature subspace and performs clustering. It uses histogram of features in the most discriminative projection to detect the number of neurons. The second algorithm performs hierarchical divisive clustering that learns a discriminative 1-dimensional subspace for clustering in each level of the hierarchy until achieving almost unimodal distribution in the subspace. The algorithms are tested on synthetic and in-vivo data, and are compared against two widely used spike sorting methods. The comparative results demonstrate that our spike sorting methods can achieve substantially higher accuracy in lower dimensional feature space, and they are highly robust to noise. Moreover, they provide significantly better cluster separab...

  14. Large Margin Linear Discriminative Visualization by Matrix Relevance Learning

    NARCIS (Netherlands)

    Biehl, Michael; Bunte, Kerstin; Schleif, Frank-Michael; Schneider, Petra; Villmann, Thomas

    2012-01-01

    We suggest and investigate the use of Generalized Matrix Relevance Learning (GMLVQ) in the context of discriminative visualization. This prototype-based, supervised learning scheme parameterizes an adaptive distance measure in terms of a matrix of relevance factors. By means of a few benchmark

  15. Learning by Analogy: Discriminating between Potential Analogs

    Science.gov (United States)

    Richland, Lindsey E.; McDonough, Ian M.

    2010-01-01

    The ability to successfully discriminate between multiple potentially relevant source analogs when solving new problems is crucial to proficiency in a mathematics domain. Experimental findings in two different mathematical contexts demonstrate that providing cues to support comparative reasoning during an initial instructional analogy, relative to…

  16. Value transfer contributes to ambiguous-cue discrimination learning.

    Science.gov (United States)

    Urcuioli, Peter J; Michalek, Sarah

    2007-08-01

    Pigeons learned two concurrent simultaneous discriminations in which the S- for one served as the S+ for the other. When all correct choices were reinforced, accuracy on the former (positive vs. ambiguous-cue or PA) discrimination was lower than on the latter (negative vs. ambiguous-cue or NA) discrimination. When correct choices on the PA discrimination were intermittently reinforced, however, pigeons chose the S- more often than the S+ on those trials. By contrast, intermittently reinforcing correct choices on the NA discrimination did not affect NA-trial accuracy but yielded higher PA-trial accuracy relative to continuous reinforcement. Together with a separate preference assessment, these results indicate that value transfer, in which some of the positive value accrued by an S+ transfers to its companion S-, contributes to ambiguous-cue performances.

  17. Racial Discrimination and Mental Health in the USA: Testing the Reverse Racism Hypothesis.

    Science.gov (United States)

    Woo, Bongki

    2017-08-15

    The present study examined whether the health disadvantages consequent of racial discrimination experienced by four racial/ethnic minority groups are equivalent with that of the dominant racial group. Data was derived from the 2013 National Epidemiologic Survey on Alcohol and Related Conditions. Logistic regression and heterogeneous choice models were used to test the moderating role of race/ethnicity in regards to the associations between racial discrimination and ten DSM-V diagnoses. Non-Hispanic blacks reported the highest levels of experiencing racial discrimination, while Non-Hispanic whites reported the lowest. Exposure to racial discrimination was associated with higher odds of psychiatric disorders for non-Hispanic blacks, non-Hispanic Asian/Pacific Islanders, and Hispanics than it was for non-Hispanic whites, while non-Hispanic American Indians/Alaska Natives had lower odds of psychiatric disorders. Analyses indicated that racial discrimination poses stronger mental health disadvantages on racial/ethnic minorities than it does to non-Hispanic whites. This finding not only refutes the notion of reverse racism, but also calls for more efforts to close the racial/ethnic health gap for those exposed to racial discrimination.

  18. Effect of donepezil on reversal learning in a touch screen-based operant task.

    Science.gov (United States)

    Chen, Woei-Shin; Wong, Fong-Kuan; Chapman, Paul F; Pemberton, Darrel J

    2009-10-01

    Impairments in reversal learning, which are commonly observed in patients with psychiatric disorders, remain difficult to treat. There is still a debate over the beneficial effects of cholinergic enhancers on improving behavioural flexibility. The objective of this study was to investigate the effect of an acetylcholinesterase inhibitor, donepezil, on the performance of a rodent Probabilistic Reversal Learning task. Lister-Hooded rats were trained to retrieve food rewards by discriminating two computer-generated stimuli in an automated touch screen-based operant task. When a steady performance was achieved, the stimulus-reward rule was reversed. Each rat was given a 30-min training session daily for 24 days and donepezil was administered 30 min before each training session. Systemic treatment with donepezil had no effect on trial accuracy of the two-stimulus discrimination training. However, the donepezil group showed enhanced performance in the reversal learning. Our result showed that treatment with donepezil significantly enhanced Probabilistic Reversal Learning performance in healthy animals. On the basis of this finding, the inhibition of the central acetylcholinesterase would seem to be a potential therapeutic approach to treat behavioural inflexibility.

  19. On Reverse Discrimination in Criminal Law%论刑法的反向歧视

    Institute of Scientific and Technical Information of China (English)

    马荣春; 谷超

    2015-01-01

    Due to the influence of sexual obligation concept of moralism , reverse discrimination exists behind the clauses of crime of rape and crime of compulsory indecency in the legislation of our country .Reverse discrimination means excessive intervention to a female ’s private sector ,w hich brings about the secondary damage to a female easily .However ,reverse discrimination is covered under the undamental principles of criminal law .If we want to eradicate the reverse discrimination in criminal aw to realize the gender equality constructed in criminal law ,we should put the social moral evaluation of female in the right place and fully respect the self‐worth of female .%在道德论和对女性性义务苛求的观念之下,我国的刑法立法在强奸罪和强制猥亵妇女罪的条文背后潜藏着反向歧视。反向歧视意味着对女性私人领域的过度干预,并容易造成“二次伤害”。但是,反向歧视却被掩盖在刑法基本原则之下。只有归位对女性的社会道德评价并充分尊重女性的自身价值,才能从根本上克除刑法的反向歧视,以实现刑法构建的性别平等。

  20. Dynamic functional brain networks involved in simple visual discrimination learning.

    Science.gov (United States)

    Fidalgo, Camino; Conejo, Nélida María; González-Pardo, Héctor; Arias, Jorge Luis

    2014-10-01

    Visual discrimination tasks have been widely used to evaluate many types of learning and memory processes. However, little is known about the brain regions involved at different stages of visual discrimination learning. We used cytochrome c oxidase histochemistry to evaluate changes in regional brain oxidative metabolism during visual discrimination learning in a water-T maze at different time points during training. As compared with control groups, the results of the present study reveal the gradual activation of cortical (prefrontal and temporal cortices) and subcortical brain regions (including the striatum and the hippocampus) associated to the mastery of a simple visual discrimination task. On the other hand, the brain regions involved and their functional interactions changed progressively over days of training. Regions associated with novelty, emotion, visuo-spatial orientation and motor aspects of the behavioral task seem to be relevant during the earlier phase of training, whereas a brain network comprising the prefrontal cortex was found along the whole learning process. This study highlights the relevance of functional interactions among brain regions to investigate learning and memory processes. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Different levels of food restriction reveal genotype-specific differences in learning a visual discrimination task.

    Directory of Open Access Journals (Sweden)

    Kalina Makowiecki

    Full Text Available In behavioural experiments, motivation to learn can be achieved using food rewards as positive reinforcement in food-restricted animals. Previous studies reduce animal weights to 80-90% of free-feeding body weight as the criterion for food restriction. However, effects of different degrees of food restriction on task performance have not been assessed. We compared learning task performance in mice food-restricted to 80 or 90% body weight (BW. We used adult wildtype (WT; C57Bl/6j and knockout (ephrin-A2⁻/⁻ mice, previously shown to have a reverse learning deficit. Mice were trained in a two-choice visual discrimination task with food reward as positive reinforcement. When mice reached criterion for one visual stimulus (80% correct in three consecutive 10 trial sets they began the reverse learning phase, where the rewarded stimulus was switched to the previously incorrect stimulus. For the initial learning and reverse phase of the task, mice at 90%BW took almost twice as many trials to reach criterion as mice at 80%BW. Furthermore, WT 80 and 90%BW groups significantly differed in percentage correct responses and learning strategy in the reverse learning phase, whereas no differences between weight restriction groups were observed in ephrin-A2⁻/⁻ mice. Most importantly, genotype-specific differences in reverse learning strategy were only detected in the 80%BW groups. Our results indicate that increased food restriction not only results in better performance and a shorter training period, but may also be necessary for revealing behavioural differences between experimental groups. This has important ethical and animal welfare implications when deciding extent of diet restriction in behavioural studies.

  2. Discriminative object tracking via sparse representation and online dictionary learning.

    Science.gov (United States)

    Xie, Yuan; Zhang, Wensheng; Li, Cuihua; Lin, Shuyang; Qu, Yanyun; Zhang, Yinghua

    2014-04-01

    We propose a robust tracking algorithm based on local sparse coding with discriminative dictionary learning and new keypoint matching schema. This algorithm consists of two parts: the local sparse coding with online updated discriminative dictionary for tracking (SOD part), and the keypoint matching refinement for enhancing the tracking performance (KP part). In the SOD part, the local image patches of the target object and background are represented by their sparse codes using an over-complete discriminative dictionary. Such discriminative dictionary, which encodes the information of both the foreground and the background, may provide more discriminative power. Furthermore, in order to adapt the dictionary to the variation of the foreground and background during the tracking, an online learning method is employed to update the dictionary. The KP part utilizes refined keypoint matching schema to improve the performance of the SOD. With the help of sparse representation and online updated discriminative dictionary, the KP part are more robust than the traditional method to reject the incorrect matches and eliminate the outliers. The proposed method is embedded into a Bayesian inference framework for visual tracking. Experimental results on several challenging video sequences demonstrate the effectiveness and robustness of our approach.

  3. Quantitative trait loci associated with reversal learning and latent inhibition in honeybees (Apis mellifera).

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    Chandra, S B; Hunt, G J; Cobey, S; Smith, B H

    2001-05-01

    A study was conducted to identify quantitative trait loci (QTLs) that affect learning in honeybees. Two F1 supersister queens were produced from a cross between two established lines that had been selected for differences in the speed at which they reverse a learned discrimination between odors. Different families of haploid drones from two of these F1 queens were evaluated for two kinds of learning performance--reversal learning and latent inhibition--which previously showed correlated selection responses. Random amplified polymorphic DNA markers were scored from recombinant, haploid drone progeny that showed extreme manifestations of learning performance. Composite interval mapping procedures identified two QTLs for reversal learning (lrn2 and lrn3: LOD, 2.45 and 2.75, respectively) and one major QTL for latent inhibition (lrn1: LOD, 6.15). The QTL for latent inhibition did not map to either of the linkage groups that were associated with reversal learning. Identification of specific genes responsible for these kinds of QTL associations will open up new windows for better understanding of genes involved in learning and memory.

  4. Weighted Discriminative Dictionary Learning based on Low-rank Representation

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    Chang, Heyou; Zheng, Hao

    2017-01-01

    Low-rank representation has been widely used in the field of pattern classification, especially when both training and testing images are corrupted with large noise. Dictionary plays an important role in low-rank representation. With respect to the semantic dictionary, the optimal representation matrix should be block-diagonal. However, traditional low-rank representation based dictionary learning methods cannot effectively exploit the discriminative information between data and dictionary. To address this problem, this paper proposed weighted discriminative dictionary learning based on low-rank representation, where a weighted representation regularization term is constructed. The regularization associates label information of both training samples and dictionary atoms, and encourages to generate a discriminative representation with class-wise block-diagonal structure, which can further improve the classification performance where both training and testing images are corrupted with large noise. Experimental results demonstrate advantages of the proposed method over the state-of-the-art methods.

  5. Visual Discrimination Learning with Variable Irrelevant Cues in Autistic Children.

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    Miyashita, Teruko

    1985-01-01

    Ten autistic children and 10 normal nursery school children, matched for mean developmental age, were presented with figure stimuli and had variable irrelevant cues in two-choice simultaneous discrimination learning. Performance of the autistic group did not vary as a function of irrelevant variability, a result attributed to poor performance of…

  6. Limited Rank Matrix Learning, discriminative dimension reduction and visualization

    NARCIS (Netherlands)

    Bunte, Kerstin; Schneider, Petra; Hammer, Barbara; Schleif, Frank-Michael; Villmann, Thomas; Biehl, Michael

    2012-01-01

    We present an extension of the recently introduced Generalized Matrix Learning Vector Quantization algorithm. In the original scheme, adaptive square matrices of relevance factors parameterize a discriminative distance measure. We extend the scheme to matrices of limited rank corresponding to low-di

  7. Employment Discrimination Law for the Learning Disabled Community.

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    Grossman, Paul David

    1992-01-01

    This article delineates legal protections prohibiting employment discrimination of individuals with learning disabilities. The Rehabilitation Act of 1973 (Title V) and Americans with Disabilities Act (Title I) are described, fundamental concepts are discussed, and strategies are presented for ensuring that these laws are relied upon appropriately…

  8. Discrimination Evidence for Examining Fourth Grade Students' Learning Disability Problems

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    Hassan, Abdulhameed S.; Al-Harthy, Ibrahim S.

    2014-01-01

    This study investigated the ability of discriminate variables (perceptual-motor, hyperactivity disorder, neurological and psychological skills) to distinguish between normal (n = 68) and students with learning disabilities (n = 72) in fourth grade. Three instruments were developed: perceptual-motor scale, hyperactivity disorder scale, skills test…

  9. Relational-Regularized Discriminative Sparse Learning for Alzheimer's Disease Diagnosis.

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    Lei, Baiying; Yang, Peng; Wang, Tianfu; Chen, Siping; Ni, Dong

    2017-01-16

    Accurate identification and understanding informative feature is important for early Alzheimer's disease (AD) prognosis and diagnosis. In this paper, we propose a novel discriminative sparse learning method with relational regularization to jointly predict the clinical score and classify AD disease stages using multimodal features. Specifically, we apply a discriminative learning technique to expand the class-specific difference and include geometric information for effective feature selection. In addition, two kind of relational information are incorporated to explore the intrinsic relationships among features and training subjects in terms of similarity learning. We map the original feature into the target space to identify the informative and predictive features by sparse learning technique. A unique loss function is designed to include both discriminative learning and relational regularization methods. Experimental results based on a total of 805 subjects [including 226 AD patients, 393 mild cognitive impairment (MCI) subjects, and 186 normal controls (NCs)] from AD neuroimaging initiative database show that the proposed method can obtain a classification accuracy of 94.68% for AD versus NC, 80.32% for MCI versus NC, and 74.58% for progressive MCI versus stable MCI, respectively. In addition, we achieve remarkable performance for the clinical scores prediction and classification label identification, which has efficacy for AD disease diagnosis and prognosis. The algorithm comparison demonstrates the effectiveness of the introduced learning techniques and superiority over the state-of-the-arts methods.

  10. Learning discriminative functional network features of schizophrenia

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    Gheiratmand, Mina; Rish, Irina; Cecchi, Guillermo; Brown, Matthew; Greiner, Russell; Bashivan, Pouya; Polosecki, Pablo; Dursun, Serdar

    2017-03-01

    Associating schizophrenia with disrupted functional connectivity is a central idea in schizophrenia research. However, identifying neuroimaging-based features that can serve as reliable "statistical biomarkers" of the disease remains a challenging open problem. We argue that generalization accuracy and stability of candidate features ("biomarkers") must be used as additional criteria on top of standard significance tests in order to discover more robust biomarkers. Generalization accuracy refers to the utility of biomarkers for making predictions about individuals, for example discriminating between patients and controls, in novel datasets. Feature stability refers to the reproducibility of the candidate features across different datasets. Here, we extracted functional connectivity network features from fMRI data at both high-resolution (voxel-level) and a spatially down-sampled lower-resolution ("supervoxel" level). At the supervoxel level, we used whole-brain network links, while at the voxel level, due to the intractably large number of features, we sampled a subset of them. We compared statistical significance, stability and discriminative utility of both feature types in a multi-site fMRI dataset, composed of schizophrenia patients and healthy controls. For both feature types, a considerable fraction of features showed significant differences between the two groups. Also, both feature types were similarly stable across multiple data subsets. However, the whole-brain supervoxel functional connectivity features showed a higher cross-validation classification accuracy of 78.7% vs. 72.4% for the voxel-level features. Cross-site variability and heterogeneity in the patient samples in the multi-site FBIRN dataset made the task more challenging compared to single-site studies. The use of the above methodology in combination with the fully data-driven approach using the whole brain information have the potential to shed light on "biomarker discovery" in schizophrenia.

  11. Deep brain stimulation in the lateral orbitofrontal cortex impairs spatial reversal learning.

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    Klanker, Marianne; Post, Ger; Joosten, Ruud; Feenstra, Matthijs; Denys, Damiaan

    2013-05-15

    Deep Brain Stimulation (DBS) is a successful novel treatment for treatment-resistant obsessive-compulsive disorder and is currently under investigation for addiction and eating disorders. Clinical and preclinical studies have shown functional changes in the orbitofrontal cortex (OFC) following DBS in the ventral capsule/ventral striatum. These findings suggest that DBS can affect neural activity in distant regions that are connected to the site of electrode implantation. However, the behavioral consequences of direct OFC stimulation are not known. Here, we studied the effects of direct stimulation in the lateral OFC on spatial discrimination and reversal learning in rats. Rats were implanted with stimulating electrodes and were trained on a spatial discrimination and reversal learning task. DBS in the OFC did not affect acquisition of a spatial discrimination. Stimulated animals made more incorrect responses during the first reversal. Acquisition of the second reversal was not affected. These results suggest that DBS may inhibit activity in the OFC, or may disrupt output of the OFC to other cortical or subcortical areas, resulting in perseverative behavior or an inability to adapt behavior to altered response-reward contingencies.

  12. Cholecystokinin as a stimulus in drug discrimination learning.

    Science.gov (United States)

    Melton, P M; Kopman, J A; Riley, A L

    1993-02-01

    Animals were trained to discriminate a relatively low dose of the octapeptide cholecystokinin (CCK) from distilled water within the conditioned taste aversion baseline of drug discrimination learning. Specifically, rats were injected with CCK (5.6 micrograms/kg) prior to the presentation of saccharin-LiCl pairings and with the CCK vehicle prior to the presentation of saccharin alone. After 10 conditioning trials (40 days), subjects acquired the discrimination, avoiding saccharin consumption following administration of CCK and consuming the same saccharin solution following the drug vehicle. Once the discrimination was acquired, a generalization function was determined for doses above and below that of the training stimulus. At doses below the training dose of CCK (i.e., 0, 3.2, and 4.2 micrograms/kg), subjects drank at control levels, whereas at the training dose and above (10 micrograms/kg) subjects significantly reduced consumption. That a relatively low dose of CCK can be used as a discriminative stimulus within a drug discrimination design may be important in that the procedure can now be used in the assessment of the pharmacological characteristics of CCK at a dose similar to that used in other behavioral assessments of the compound.

  13. Learning Dictionaries of Discriminative Image Patches

    DEFF Research Database (Denmark)

    Dahl, Anders Lindbjerg; Larsen, Rasmus

    2011-01-01

    Remarkable results have been obtained using image models based on image patches, for example sparse generative models for image inpainting, noise reduction and superresolution, sparse texture segmentation or texton models. In this paper we propose a powerful and yet simple approach for segmentation...... using dictionaries of image patches with associated label data. The approach is based on ideas from sparse generative image models and texton based texture modeling. The intensity and label dictionaries are learned from training images with associated label information of (a subset) of the pixels based...

  14. Dorsal striatal D2-like receptor availability covaries with sensitivity to positive reinforcement during discrimination learning.

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    Groman, Stephanie M; Lee, Buyean; London, Edythe D; Mandelkern, Mark A; James, Alex S; Feiler, Karen; Rivera, Ronald; Dahlbom, Magnus; Sossi, Vesna; Vandervoort, Eric; Jentsch, J David

    2011-05-18

    Deviations in reward sensitivity and behavioral flexibility, particularly in the ability to change or stop behaviors in response to changing environmental contingencies, are important phenotypic dimensions of several neuropsychiatric disorders. Neuroimaging evidence suggests that variation in dopamine signaling through dopamine D(2)-like receptors may influence these phenotypes, as well as associated psychiatric conditions, but the specific neurocognitive mechanisms through which this influence is exerted are unknown. To address this question, we examined the relationship between behavioral sensitivity to reinforcement during discrimination learning and D(2)-like receptor availability in vervet monkeys. Monkeys were assessed for their ability to acquire, retain, and reverse three-choice, visual-discrimination problems, and once behavioral performance had stabilized, they received positron emission tomography (PET) scans. D(2)-like receptor availability in dorsal aspects of the striatum was not related to individual differences in the ability to acquire or retain visual discriminations but did relate to the number of trials required to reach criterion in the reversal phase of the task. D(2)-like receptor availability was also strongly correlated with behavioral sensitivity to positive, but not negative, feedback during learning. These results go beyond electrophysiological findings by demonstrating the involvement of a striatal dopaminergic marker in individual differences in feedback sensitivity and behavioral flexibility, providing insight into the neural mechanisms that are affected in neuropsychiatric disorders that feature these deficits.

  15. Statistical Learning, Letter Reversals, and Reading

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    Treiman, Rebecca; Gordon, Jessica; Boada, Richard; Peterson, Robin L.; Pennington, Bruce F.

    2014-01-01

    Reversal errors play a prominent role in theories of reading disability. We examined reversal errors in the writing of letters by 5- to 6-year-old children. Of the 130 children, 92 had a history of difficulty in producing speech sounds, a risk factor for reading problems. Children were more likely to reverse letter forms that face left, such as…

  16. Visual tracker using sequential bayesian learning: discriminative, generative, and hybrid.

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    Lei, Yun; Ding, Xiaoqing; Wang, Shengjin

    2008-12-01

    This paper presents a novel solution to track a visual object under changes in illumination, viewpoint, pose, scale, and occlusion. Under the framework of sequential Bayesian learning, we first develop a discriminative model-based tracker with a fast relevance vector machine algorithm, and then, a generative model-based tracker with a novel sequential Gaussian mixture model algorithm. Finally, we present a three-level hierarchy to investigate different schemes to combine the discriminative and generative models for tracking. The presented hierarchical model combination contains the learner combination (at level one), classifier combination (at level two), and decision combination (at level three). The experimental results with quantitative comparisons performed on many realistic video sequences show that the proposed adaptive combination of discriminative and generative models achieves the best overall performance. Qualitative comparison with some state-of-the-art methods demonstrates the effectiveness and efficiency of our method in handling various challenges during tracking.

  17. Motivational Classroom Climate for Learning Mathematics: A Reversal Theory Perspective

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    Lewis, Gareth

    2015-01-01

    In this article, a case is made that affect is central in determining students' experience of learning or not learning mathematics. I show how reversal theory (Apter, 2001), and particularly its taxonomy of motivations and emotions, provides a basis for a thick description of students' experiences of learning in a mathematics classroom. Using data…

  18. Spatial discrimination and visual discrimination: two methods evaluating learning and memory in juvenile Göttingen minipigs.

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    Haagensen, Annika M J; Grand, Nanna; Klastrup, Signe; Skytte, Christina; Sørensen, Dorte B

    2013-06-01

    Two methods investigating learning and memory in juvenile Göttingen minipigs were evaluated for potential use in preclinical toxicity testing. Twelve minipigs were tested using a spatial hole-board discrimination test including a learning phase and two memory phases. Five minipigs were tested in a visual discrimination test. The juvenile minipigs were able to learn the spatial hole-board discrimination test and showed improved working and reference memory during the learning phase. Performance in the memory phases was affected by the retention intervals, but the minipigs were able to remember the concept of the test in both memory phases. Working memory and reference memory were significantly improved in the last trials of the memory phases. In the visual discrimination test, the minipigs learned to discriminate between the three figures presented to them within 9-14 sessions. For the memory test, all minipigs performed 9/12 correct choices or better. Juvenile Göttingen minipigs are able to learn to perform in a spatial hole-board discrimination test as well as in a visual discrimination test, showing an increase in performance over time. Both tests have considerable scope to assess learning and memory of pigs, and we seem to have succeeded in establishing two test systems suitable for performing preclinical toxicity testing in juvenile minipigs.

  19. Neighbors Based Discriminative Feature Difference Learning for Kinship Verification

    DEFF Research Database (Denmark)

    Duan, Xiaodong; Tan, Zheng-Hua

    2015-01-01

    than the commonly used feature concatenation, leading to a low complexity. Furthermore, there is no positive semi-definitive constrain on the transformation matrix while there is in metric learning methods, leading to an easy solution for the transformation matrix. Experimental results on two public......In this paper, we present a discriminative feature difference learning method for facial image based kinship verification. To transform feature difference of an image pair to be discriminative for kinship verification, a linear transformation matrix for feature difference between an image pair...... is inferred from training data. This transformation matrix is obtained through minimizing the difference of L2 norm between the feature difference of each kinship pair and its neighbors from non-kinship pairs. To find the neighbors, a cosine similarity is applied. Our method works on feature difference rather...

  20. Hybrid Generative/Discriminative Learning for Automatic Image Annotation

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    Yang, Shuang Hong; Zha, Hongyuan

    2012-01-01

    Automatic image annotation (AIA) raises tremendous challenges to machine learning as it requires modeling of data that are both ambiguous in input and output, e.g., images containing multiple objects and labeled with multiple semantic tags. Even more challenging is that the number of candidate tags is usually huge (as large as the vocabulary size) yet each image is only related to a few of them. This paper presents a hybrid generative-discriminative classifier to simultaneously address the extreme data-ambiguity and overfitting-vulnerability issues in tasks such as AIA. Particularly: (1) an Exponential-Multinomial Mixture (EMM) model is established to capture both the input and output ambiguity and in the meanwhile to encourage prediction sparsity; and (2) the prediction ability of the EMM model is explicitly maximized through discriminative learning that integrates variational inference of graphical models and the pairwise formulation of ordinal regression. Experiments show that our approach achieves both su...

  1. Differential effects of M1 muscarinic receptor blockade and nicotinic receptor blockade in the dorsomedial striatum on response reversal learning

    Science.gov (United States)

    Tzavos, Arianna; Jih, Jane; Ragozzino, Michael E.

    2011-01-01

    The present studies determined whether blockade of M1-like muscarinic or nicotinic cholinergic receptors in the dorsomedial striatum affects acquisition or reversal learning of a response discrimination. Testing occurred in a modified cross-maze across two consecutive sessions. In the acquisition phase, a rat learned to turn to the left or to the right. In the reversal learning phase, a rat learned to turn in the opposite direction as required during acquisition. Experiment 1 investigated the effects of the M1-like muscarinic receptor antagonist, pirenzepine infused into the dorsomedial striatum on acquisition and reversal learning. Experiment 2 examined the effects of the nicotinic cholinergic antagonist, mecamylamine injected into the dorsomedial striatum on acquisition and reversal learning. Bilateral injections of pirenzepine at 10 µg, but not 1 µg, selectively impaired reversal learning. Analysis of the errors indicated that pirenzepine treatment did not impair the initial shift, but increased reversions back to the original response choice following the initial shift. Bilateral injections of mecamylamine, 6 or 18 µg, did not affect acquisition or reversal learning. The results suggest that activation of M1 muscarinic cholinergic receptors, but not nicotinic cholinergic receptors, in the dorsomedial striatum is important for facilitating the flexible shifting of response patterns. PMID:15302131

  2. Effects of X-ray radiation on complex visual discrimination learning and social recognition memory in rats.

    Directory of Open Access Journals (Sweden)

    Catherine M Davis

    Full Text Available The present report describes an animal model for examining the effects of radiation on a range of neurocognitive functions in rodents that are similar to a number of basic human cognitive functions. Fourteen male Long-Evans rats were trained to perform an automated intra-dimensional set shifting task that consisted of their learning a basic discrimination between two stimulus shapes followed by more complex discrimination stages (e.g., a discrimination reversal, a compound discrimination, a compound reversal, a new shape discrimination, and an intra-dimensional stimulus discrimination reversal. One group of rats was exposed to head-only X-ray radiation (2.3 Gy at a dose rate of 1.9 Gy/min, while a second group received a sham-radiation exposure using the same anesthesia protocol. The irradiated group responded less, had elevated numbers of omitted trials, increased errors, and greater response latencies compared to the sham-irradiated control group. Additionally, social odor recognition memory was tested after radiation exposure by assessing the degree to which rats explored wooden beads impregnated with either their own odors or with the odors of novel, unfamiliar rats; however, no significant effects of radiation on social odor recognition memory were observed. These data suggest that rodent tasks assessing higher-level human cognitive domains are useful in examining the effects of radiation on the CNS, and may be applicable in approximating CNS risks from radiation exposure in clinical populations receiving whole brain irradiation.

  3. Subchronic anesthetic ketamine injections in rats impair choice reversal learning, but have no effect on reinforcer devaluation.

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    Pickens, Charles L; Aurand, Lexia; Hunt, Joshua; Fisher, Hayley

    2017-01-21

    Previous exposure to a variety of drugs of abuse has been shown to cause long-term impairments in reversal learning and reinforcer devaluation tasks. However, there is mixed evidence in the literature for a long-term effect of ketamine exposure on reversal learning and the long-term effect of ketamine exposure on devaluation is not known. We determined whether repeated injections of an anesthetic dose of ketamine would lead to impairments in choice reversal learning after discrimination learning or impairments in reinforcer devaluation. In two experiments, rats received three injections once-daily of ketamine (100 mg/kg, intraperitoneally) or saline and then began behavioral training 19 days later so that the key reversal learning and devaluation tests would occur about 1 month after the final ketamine injection. This ketamine exposure regimen did not impair learning in our discrimination task, but led to an increase in perseverative errors in reversal learning. However, the same ketamine exposure regimen (or injections of a lower 50 mg/kg dose) had no effect on behavior in the devaluation task. The behavioral patterns observed suggest possible neural mechanisms for the effects of ketamine, but future neurobiological investigations will be needed to isolate these mechanisms.

  4. No evidence for learned mating discrimination in male Drosophila pseudoobscura

    Directory of Open Access Journals (Sweden)

    Kandul Ekaterina V

    2006-07-01

    Full Text Available Abstract Background Since females often pay a higher cost for heterospecific matings, mate discrimination and species recognition are driven primarily by female choice. In contrast, frequent indiscriminate matings are hypothesized to maximize male fitness. However, recent studies show that previously indiscriminate males (e.g., Drosophila melanogaster and Poecilia reticulata can learn to avoid heterospecific courtship. This ability of males to discriminate against heterospecific courtship may be advantageous in populations where two species co-occur if courtship or mating is costly. Results Here, we tested whether Drosophila pseudoobscura males learn to discriminate against heterospecific females after being exposed to and rejected by D. persimilis females. In most of our assays, we failed to observe differences in D. pseudoobscura courtship intensity of heterospecific females by males that had previously courted heterospecific females vs. males that had been maintained in isolation. Conclusion We conclude that learning to avoid heterospecific courtship may not be universal, even within the genus Drosophila, and may possibly be dependent on the natural history of the species.

  5. Bilevel Model-Based Discriminative Dictionary Learning for Recognition.

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    Zhou, Pan; Zhang, Chao; Lin, Zhouchen

    2017-03-01

    Most supervised dictionary learning methods optimize the combinations of reconstruction error, sparsity prior, and discriminative terms. Thus, the learnt dictionaries may not be optimal for recognition tasks. Also, the sparse codes learning models in the training and the testing phases are inconsistent. Besides, without utilizing the intrinsic data structure, many dictionary learning methods only employ the l0 or l1 norm to encode each datum independently, limiting the performance of the learnt dictionaries. We present a novel bilevel model-based discriminative dictionary learning method for recognition tasks. The upper level directly minimizes the classification error, while the lower level uses the sparsity term and the Laplacian term to characterize the intrinsic data structure. The lower level is subordinate to the upper level. Therefore, our model achieves an overall optimality for recognition in that the learnt dictionary is directly tailored for recognition. Moreover, the sparse codes learning models in the training and the testing phases can be the same. We further propose a novel method to solve our bilevel optimization problem. It first replaces the lower level with its Karush-Kuhn-Tucker conditions and then applies the alternating direction method of multipliers to solve the equivalent problem. Extensive experiments demonstrate the effectiveness and robustness of our method.

  6. Selective aspiration or neurotoxic lesions of orbital frontal areas 11 and 13 spared monkeys' performance on the object discrimination reversal task.

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    Kazama, Andy; Bachevalier, Jocelyne

    2009-03-04

    Damage to the orbital frontal cortex (OFC) has long been associated with reversal learning deficits in several species. In monkeys, this impairment follows lesions that include several OFC subfields. However, the different connectional patterns of OFC subfields together with neuroimaging data in humans have suggested that specific OFC areas play distinctive roles in processing information necessary to guide behavior (Kringelbach and Rolls, 2004; Barbas, 2007; Price, 2007). More specifically, areas 11 and 13 contribute to a sensory network, whereas medial areas 10, 14, and 25 are heavily connected to a visceromotor network. To examine the contribution of areas 11 and 13 to reversal learning, we tested monkeys with selective damage to these two OFC areas on two versions of the ODR task using either one or five discrimination problems. We compared their performance with that of sham-operated controls and of animals with neurotoxic amygdala lesions, which served as operated controls. Neither damage to areas 11 and 13 nor damage to the amygdala affected performance on the ODR tasks. The results indicate that areas 11 and 13 do not critically contribute to reversal learning and that adjacent damage to OFC subfields (10, 12, 14, and 25) could account for the ODR deficits found in earlier lesion studies. This sparing of reversal learning will be discussed in relation to deficits found in the same animals on tasks that measure behavioral modulation when relative value of affective (positive and negative) stimuli was manipulated.

  7. EXEL; Experience for Children in Learning. Parent-Directed Activities to Develop: Oral Expression, Visual Discrimination, Auditory Discrimination, Motor Coordination.

    Science.gov (United States)

    Behrmann, Polly; Millman, Joan

    The activities collected in this handbook are planned for parents to use with their children in a learning experience. They can also be used in the classroom. Sections contain games designed to develop visual discrimination, auditory discrimination, motor coordination and oral expression. An objective is given for each game, and directions for…

  8. Semi-supervised learning for ordinal Kernel Discriminant Analysis.

    Science.gov (United States)

    Pérez-Ortiz, M; Gutiérrez, P A; Carbonero-Ruz, M; Hervás-Martínez, C

    2016-12-01

    Ordinal classification considers those classification problems where the labels of the variable to predict follow a given order. Naturally, labelled data is scarce or difficult to obtain in this type of problems because, in many cases, ordinal labels are given by a user or expert (e.g. in recommendation systems). Firstly, this paper develops a new strategy for ordinal classification where both labelled and unlabelled data are used in the model construction step (a scheme which is referred to as semi-supervised learning). More specifically, the ordinal version of kernel discriminant learning is extended for this setting considering the neighbourhood information of unlabelled data, which is proposed to be computed in the feature space induced by the kernel function. Secondly, a new method for semi-supervised kernel learning is devised in the context of ordinal classification, which is combined with our developed classification strategy to optimise the kernel parameters. The experiments conducted compare 6 different approaches for semi-supervised learning in the context of ordinal classification in a battery of 30 datasets, showing (1) the good synergy of the ordinal version of discriminant analysis and the use of unlabelled data and (2) the advantage of computing distances in the feature space induced by the kernel function.

  9. Excitotoxic lesions of the infralimbic, but not prelimbic cortex facilitate reversal of appetitive discriminative context conditioning: the role of the infralimbic cortex in context generalisation.

    Directory of Open Access Journals (Sweden)

    Rachel eAshwell

    2014-02-01

    Full Text Available The prelimbic and infralimbic regions of the rat medial prefrontal cortex (mPFC are important components of the limbic cortico-striatal circuit, receiving converging projections from the hippocampus (HPC and amygdala. Mounting evidence points to these regions having opposing roles in the regulation of the expression of contextual fear and context-induced cocaine-seeking. To investigate this functional differentiation in motivated behaviour further, this study employed a novel radial maze task previously shown to be dependent on the integrity of the hippocampus and its functional connection to the nucleus accumbens shell, to investigate the effects of selective excitotoxic lesions of the PL and IL upon the spatial contextual control over reward learning. To this end, rats were trained to develop discriminative responding towards a reward-associated discrete cue presented in three out of six spatial locations (3 arms out of 6 radial maze arms, and to avoid the same discrete cue presented in the other 3 spatial locations. Once acquired, the reward contingencies of the spatial locations were reversed, such that responding to the cue presented in a previously rewarded location is no longer rewarded. Furthermore, the acquisition of spatial learning was probed separately using conditioned place preference and the monitoring of arm selection at the beginning of each training session. Lesions of the PL transiently attenuated the acquisition of the initial cue approach training and spatial learning, while leaving reversal learning intact. In contrast, IL lesions led to a significantly superior performance of spatial context-dependent discriminative cue approach and reversal learning, in the absence of a significant preference for the new reward-associated spatial locations. These results indicate that the PL and IL have functionally dissociative, and potentially opposite roles in the regulation of spatial contextual control over appetitive learning.

  10. Peak shift discrimination learning as a mechanism of signal evolution.

    Science.gov (United States)

    Lynn, Spencer K; Cnaani, Jonathan; Papaj, Daniel R

    2005-06-01

    "Peak shift" is a behavioral response bias arising from discrimination learning in which animals display a directional, but limited, preference for or avoidance of unusual stimuli. Its hypothesized evolutionary relevance has been primarily in the realm of aposematic coloration and limited sexual dimorphism. Here, we develop a novel functional approach to peak shift, based on signal detection theory, which characterizes the response bias as arising from uncertainty about stimulus appearance, frequency, and quality. This approach allows the influence of peak shift to be generalized to the evolution of signals in a variety of domains and sensory modalities. The approach is illustrated with a bumblebee (Bombus impatiens) discrimination learning experiment. Bees exhibited peak shift while foraging in an artificial Batesian mimicry system. Changes in flower abundance, color distribution, and visitation reward induced bees to preferentially visit novel flower colors that reduced the risk of flower-type misidentification. Under conditions of signal uncertainty, peak shift results in visitation to rarer, but more easily distinguished, morphological variants of rewarding species in preference to their average morphology. Peak shift is a common and taxonomically widespread phenomenon. This example of the possible role of peak shift in signal evolution can be generalized to other systems in which a signal receiver learns to make choices in situations in which signal variation is linked to the sender's reproductive success.

  11. Discriminative Unsupervised Feature Learning with Exemplar Convolutional Neural Networks.

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    Dosovitskiy, Alexey; Fischer, Philipp; Springenberg, Jost Tobias; Riedmiller, Martin; Brox, Thomas

    2016-09-01

    Deep convolutional networks have proven to be very successful in learning task specific features that allow for unprecedented performance on various computer vision tasks. Training of such networks follows mostly the supervised learning paradigm, where sufficiently many input-output pairs are required for training. Acquisition of large training sets is one of the key challenges, when approaching a new task. In this paper, we aim for generic feature learning and present an approach for training a convolutional network using only unlabeled data. To this end, we train the network to discriminate between a set of surrogate classes. Each surrogate class is formed by applying a variety of transformations to a randomly sampled 'seed' image patch. In contrast to supervised network training, the resulting feature representation is not class specific. It rather provides robustness to the transformations that have been applied during training. This generic feature representation allows for classification results that outperform the state of the art for unsupervised learning on several popular datasets (STL-10, CIFAR-10, Caltech-101, Caltech-256). While features learned with our approach cannot compete with class specific features from supervised training on a classification task, we show that they are advantageous on geometric matching problems, where they also outperform the SIFT descriptor.

  12. Learning Discriminative Stein Kernel for SPD Matrices and Its Applications.

    Science.gov (United States)

    Zhang, Jianjia; Wang, Lei; Zhou, Luping; Li, Wanqing

    2016-05-01

    Stein kernel (SK) has recently shown promising performance on classifying images represented by symmetric positive definite (SPD) matrices. It evaluates the similarity between two SPD matrices through their eigenvalues. In this paper, we argue that directly using the original eigenvalues may be problematic because: 1) eigenvalue estimation becomes biased when the number of samples is inadequate, which may lead to unreliable kernel evaluation, and 2) more importantly, eigenvalues reflect only the property of an individual SPD matrix. They are not necessarily optimal for computing SK when the goal is to discriminate different classes of SPD matrices. To address the two issues, we propose a discriminative SK (DSK), in which an extra parameter vector is defined to adjust the eigenvalues of input SPD matrices. The optimal parameter values are sought by optimizing a proxy of classification performance. To show the generality of the proposed method, three kernel learning criteria that are commonly used in the literature are employed as a proxy. A comprehensive experimental study is conducted on a variety of image classification tasks to compare the proposed DSK with the original SK and other methods for evaluating the similarity between SPD matrices. The results demonstrate that the DSK can attain greater discrimination and better align with classification tasks by altering the eigenvalues. This makes it produce higher classification performance than the original SK and other commonly used methods.

  13. Global discriminative learning for higher-accuracy computational gene prediction.

    Directory of Open Access Journals (Sweden)

    Axel Bernal

    2007-03-01

    Full Text Available Most ab initio gene predictors use a probabilistic sequence model, typically a hidden Markov model, to combine separately trained models of genomic signals and content. By combining separate models of relevant genomic features, such gene predictors can exploit small training sets and incomplete annotations, and can be trained fairly efficiently. However, that type of piecewise training does not optimize prediction accuracy and has difficulty in accounting for statistical dependencies among different parts of the gene model. With genomic information being created at an ever-increasing rate, it is worth investigating alternative approaches in which many different types of genomic evidence, with complex statistical dependencies, can be integrated by discriminative learning to maximize annotation accuracy. Among discriminative learning methods, large-margin classifiers have become prominent because of the success of support vector machines (SVM in many classification tasks. We describe CRAIG, a new program for ab initio gene prediction based on a conditional random field model with semi-Markov structure that is trained with an online large-margin algorithm related to multiclass SVMs. Our experiments on benchmark vertebrate datasets and on regions from the ENCODE project show significant improvements in prediction accuracy over published gene predictors that use intrinsic features only, particularly at the gene level and on genes with long introns.

  14. Hierarchical discriminant manifold learning for dimensionality reduction and image classification

    Science.gov (United States)

    Chen, Weihai; Zhao, Changchen; Ding, Kai; Wu, Xingming; Chen, Peter C. Y.

    2015-09-01

    In the field of image classification, it has been a trend that in order to deliver a reliable classification performance, the feature extraction model becomes increasingly more complicated, leading to a high dimensionality of image representations. This, in turn, demands greater computation resources for image classification. Thus, it is desirable to apply dimensionality reduction (DR) methods for image classification. It is necessary to apply DR methods to relieve the computational burden as well as to improve the classification accuracy. However, traditional DR methods are not compatible with modern feature extraction methods. A framework that combines manifold learning based DR and feature extraction in a deeper way for image classification is proposed. A multiscale cell representation is extracted from the spatial pyramid to satisfy the locality constraints for a manifold learning method. A spectral weighted mean filtering is proposed to eliminate noise in the feature space. A hierarchical discriminant manifold learning is proposed which incorporates both category label and image scale information to guide the DR process. Finally, the image representation is generated by concatenating dimensionality reduced cell representations from the same image. Extensive experiments are conducted to test the proposed algorithm on both scene and object recognition datasets in comparison with several well-established and state-of-the-art methods with respect to classification precision and computational time. The results verify the effectiveness of incorporating manifold learning in the feature extraction procedure and imply that the multiscale cell representations may be distributed on a manifold.

  15. Histopathological Image Classification Using Discriminative Feature-Oriented Dictionary Learning.

    Science.gov (United States)

    Vu, Tiep Huu; Mousavi, Hojjat Seyed; Monga, Vishal; Rao, Ganesh; Rao, U K Arvind

    2016-03-01

    In histopathological image analysis, feature extraction for classification is a challenging task due to the diversity of histology features suitable for each problem as well as presence of rich geometrical structures. In this paper, we propose an automatic feature discovery framework via learning class-specific dictionaries and present a low-complexity method for classification and disease grading in histopathology. Essentially, our Discriminative Feature-oriented Dictionary Learning (DFDL) method learns class-specific dictionaries such that under a sparsity constraint, the learned dictionaries allow representing a new image sample parsimoniously via the dictionary corresponding to the class identity of the sample. At the same time, the dictionary is designed to be poorly capable of representing samples from other classes. Experiments on three challenging real-world image databases: 1) histopathological images of intraductal breast lesions, 2) mammalian kidney, lung and spleen images provided by the Animal Diagnostics Lab (ADL) at Pennsylvania State University, and 3) brain tumor images from The Cancer Genome Atlas (TCGA) database, reveal the merits of our proposal over state-of-the-art alternatives. Moreover, we demonstrate that DFDL exhibits a more graceful decay in classification accuracy against the number of training images which is highly desirable in practice where generous training is often not available.

  16. Learning to learn during visual discrimination in group housed dwarf goats (Capra hircus).

    Science.gov (United States)

    Langbein, Jan; Siebert, Katrin; Nürnberg, Gerd; Manteuffel, Gerhard

    2007-11-01

    Using an automated learning device, we investigated "learning to learn" by dwarf goats (Capra hircus) in what was for them a familiar environment and normal social settings. Nine problems, each consisting of four discriminable black symbols, each with one S-super+ and three different S-super(-), were presented on a computer screen. Mean daily learning success improved over the course of the first four problems, and the improvement was maintained throughout the remaining five problems. The number of trials to reach the learning criterion decreased significantly beginning with problem four. Such results may be interpreted as evidence that the goats were developing a learning set. In the present case, the learning set appeared to have two components. One involved gaining familiarity and apparent understanding of the learning device and the basic requirements of the discrimination task. The second component involved learning potential error factors to be ignored, as well as learning commonalities that carried over from one problem to the next. Among the error factors, evidence of apparent preferences for specific symbols was seen, which had a predictable effect on performances.

  17. Pharmacological or genetic inactivation of the serotonin transporter improves reversal learning in mice.

    Science.gov (United States)

    Brigman, Jonathan L; Mathur, Poonam; Harvey-White, Judith; Izquierdo, Alicia; Saksida, Lisa M; Bussey, Timothy J; Fox, Stephanie; Deneris, Evan; Murphy, Dennis L; Holmes, Andrew

    2010-08-01

    Growing evidence supports a major contribution of cortical serotonin (5-hydroxytryptamine, 5-HT) to the modulation of cognitive flexibility and the cognitive inflexibility evident in neuropsychiatric disorders. The precise role of 5-HT and the influence of 5-HT gene variation in mediating this process is not fully understood. Using a touch screen-based operant system, we assessed reversal of a pairwise visual discrimination as an assay for cognitive flexibility. Effects of constitutive genetic or pharmacological inactivation of the 5-HT transporter (5-HTT) on reversal were examined by testing 5-HTT null mice and chronic fluoxetine-treated C57BL/6J mice, respectively. Effects of constitutive genetic loss or acute pharmacological depletion of 5-HT were assessed by testing Pet-1 null mice and para-chlorophenylalanine (PCPA)-treated C57BL/6J mice, respectively. Fluoxetine-treated C57BL/6J mice made fewer errors than controls during the early phase of reversal when perseverative behavior is relatively high. 5-HTT null mice made fewer errors than controls in completing the reversal task. However, reversal in Pet-1 null and PCPA-treated C57BL/6J mice was not different from controls. These data further support an important role for 5-HT in modulating reversal learning and provide novel evidence that inactivating the 5-HTT improves this process. These findings could have important implications for understanding and treating cognitive inflexibility in neuropsychiatric disease.

  18. Acute stress impairs set-shifting but not reversal learning.

    Science.gov (United States)

    Butts, K A; Floresco, S B; Phillips, A G

    2013-09-01

    The ability to update and modify previously learned behavioral responses in a changing environment is essential for successful utilization of promising opportunities and for coping with adverse events. Valid models of cognitive flexibility that contribute to behavioral flexibility include set-shifting and reversal learning. One immediate effect of acute stress is the selective impairment of performance on higher-order cognitive control tasks mediated by the medial prefrontal cortex (mPFC) but not the hippocampus. Previous studies show that the mPFC is required for set-shifting but not for reversal learning, therefore the aim of the present experiment is to assess whether exposure to acute stress (15 min of mild tail-pinch stress) given immediately before testing on either a set-shifting or reversal learning tasks would impair performance selectively on the set-shifting task. An automated operant chamber-based task, confirmed that exposure to acute stress significantly disrupts set-shifting but has no effect on reversal learning. Rats exposed to an acute stressor require significantly more trials to reach criterion and make significantly more perseverative errors. Thus, these data reveal that an immediate effect of acute stress is to impair mPFC-dependent cognition selectively by disrupting the ability to inhibit the use of a previously relevant cognitive strategy.

  19. Effects of Learning about Historical Gender Discrimination on Early Adolescents' Occupational Judgments and Aspirations

    Science.gov (United States)

    Pahlke, Erin; Bigler, Rebecca S.; Green, Vanessa A.

    2010-01-01

    To examine the consequences of learning about gender discrimination, early adolescents (n = 121, aged 10-14) were randomly assigned to receive either (a) standard biographical lessons about historical figures (standard condition) or (b) nearly identical lessons that included information about gender discrimination (discrimination condition).…

  20. Effects of Learning about Gender Discrimination on Adolescent Girls' Attitudes toward and Interest in Science

    Science.gov (United States)

    Weisgram, Erica S.; Bigler, Rebecca S.

    2007-01-01

    Gender discrimination has contributed to the gender imbalance in scientific fields. However, research on the effects of informing adolescent girls about gender discrimination in these fields is rare and controversial. To examine the consequences of learning about gender-based occupational discrimination, adolescent girls (n= 158, ages 11 to 14)…

  1. Discriminative Block-Diagonal Representation Learning for Image Recognition.

    Science.gov (United States)

    Zhang, Zheng; Xu, Yong; Shao, Ling; Yang, Jian

    2017-07-04

    Existing block-diagonal representation studies mainly focuses on casting block-diagonal regularization on training data, while only little attention is dedicated to concurrently learning both block-diagonal representations of training and test data. In this paper, we propose a discriminative block-diagonal low-rank representation (BDLRR) method for recognition. In particular, the elaborate BDLRR is formulated as a joint optimization problem of shrinking the unfavorable representation from off-block-diagonal elements and strengthening the compact block-diagonal representation under the semisupervised framework of LRR. To this end, we first impose penalty constraints on the negative representation to eliminate the correlation between different classes such that the incoherence criterion of the extra-class representation is boosted. Moreover, a constructed subspace model is developed to enhance the self-expressive power of training samples and further build the representation bridge between the training and test samples, such that the coherence of the learned intraclass representation is consistently heightened. Finally, the resulting optimization problem is solved elegantly by employing an alternative optimization strategy, and a simple recognition algorithm on the learned representation is utilized for final prediction. Extensive experimental results demonstrate that the proposed method achieves superb recognition results on four face image data sets, three character data sets, and the 15 scene multicategories data set. It not only shows superior potential on image recognition but also outperforms the state-of-the-art methods.

  2. Discriminative Ocular Artifact Correction for Feature Learning in EEG Analysis.

    Science.gov (United States)

    Li, Xinyang; Guan, Cuntai; Zhang, Haihong; Ang, Kai Keng

    2016-11-16

    Electrooculogram (EOG) artifact contamination is a common critical issue in general electroencephalogram (EEG) studies as well as in brain computer interface (BCI) research. It is especially challenging when dedicated EOG channels are unavailable or when there are very few EEG channels available for ICA-based ocular artifact removal. It is even more challenging to avoid loss of the signal of interest during the artifact correction process, where the signal of interest can be multiple magnitudes weaker than the artifact. To address these issues, we propose a novel discriminative ocular artifact correction approach for feature learning in EEG analysis.Without extra ocular movement measurements, the artifact is extracted from raw EEG data, which is totally automatic and requires no visual inspection of artifacts. Then, artifact correction is optimized jointly with feature extraction by maximizing oscillatory correlations between trials from the same class and minimizing them between trials from different classes. We evaluate this approach on a real world EEG data set comprising 68 subjects performing cognitive tasks. The results showed that the approach is capable of not only suppressing the artifact components but also improving the discriminative power of a classifier with statistical significance. We also demonstrate that the proposed method addresses the confounding issues induced by ocular movements in cognitive EEG study.

  3. Discrimination of approved drugs from experimental drugs by learning methods

    Directory of Open Access Journals (Sweden)

    Li Yixue

    2011-05-01

    Full Text Available Abstract Background To assess whether a compound is druglike or not as early as possible is always critical in drug discovery process. There have been many efforts made to create sets of 'rules' or 'filters' which, it is hoped, will help chemists to identify 'drug-like' molecules from 'non-drug' molecules. However, among the chemical space of the druglike molecules, the minority will be approved drugs. Classifying approved drugs from experimental drugs may be more helpful to obtain future approved drugs. Therefore, discrimination of approved drugs from experimental ones has been done in this paper by analyzing the compounds in terms of existing drugs features and machine learning methods. Results Four methodologies were compared by their performance to classify approved drugs from experimental ones. The best results were obtained by SVM, in which the accuracy is 0.7911, the sensitivity is 0.5929, and the specificity is 0.8743. Based on the results, consensus model was developed to effectively discriminate drugs, which further pushed the correct classification rate up to 0.8517, sensitivity up to 0.7242, specificity up to 0.9352. The applications on the Traditional Chinese Medicine Ingredients Database (TCM-ID tested the methods. Therefore this model has been proven to be a potent tool for identifying drug molecules. Conclusion The studies would have potential applications in the research of combinatorial library design and virtual high throughput screening for drug discovery.

  4. Learning course adjustments during arm movements with reversed sensitivity derivatives

    Directory of Open Access Journals (Sweden)

    Tweed Douglas B

    2010-11-01

    Full Text Available Abstract Background To learn, a motor system needs to know its sensitivity derivatives, which quantify how its neural commands affect motor error. But are these derivatives themselves learned, or are they known solely innately? Here we test a recent theory that the brain's estimates of sensitivity derivatives are revisable based on sensory feedback. In its simplest form, the theory says that each control system has a single, adjustable estimate of its sensitivity derivatives which affects all aspects of its task, e.g. if you learn to reach to mirror-reversed targets then your revised estimate should reverse not only your initial aiming but also your online course adjustments when the target jumps in mid-movement. Methods Human subjects bent a joystick to move a cursor to a target on a computer screen, but the cursor's motion was reversed relative to the joystick's. The target jumped once during each movement. Subjects had up to 4000 trials to practice aiming and responding to target jumps. Results All subjects learned to reverse both initial aiming and course adjustments. Conclusions Our study confirms that sensitivity derivatives can be relearned. It is consistent with the idea of a single, all-purpose estimate of those derivatives; and it suggests that the estimate is a function of context, as one would expect given that the true sensitivity derivatives may vary with the state of the controlled system, the target, and the motor commands.

  5. Discrimination

    National Research Council Canada - National Science Library

    Midtbøen, Arnfinn H; Rogstad, Jon

    2012-01-01

    ... of discrimination in the labour market as well as to the mechanisms involved in discriminatory hiring practices. The design has several advantages compared to -‘single-method’ approaches and provides a more substantial understanding of the processes leading to ethnic inequality in the labour market.

  6. Learning Discriminative Subspaces on Random Contrasts for Image Saliency Analysis.

    Science.gov (United States)

    Fang, Shu; Li, Jia; Tian, Yonghong; Huang, Tiejun; Chen, Xiaowu

    2017-05-01

    In visual saliency estimation, one of the most challenging tasks is to distinguish targets and distractors that share certain visual attributes. With the observation that such targets and distractors can sometimes be easily separated when projected to specific subspaces, we propose to estimate image saliency by learning a set of discriminative subspaces that perform the best in popping out targets and suppressing distractors. Toward this end, we first conduct principal component analysis on massive randomly selected image patches. The principal components, which correspond to the largest eigenvalues, are selected to construct candidate subspaces since they often demonstrate impressive abilities to separate targets and distractors. By projecting images onto various subspaces, we further characterize each image patch by its contrasts against randomly selected neighboring and peripheral regions. In this manner, the probable targets often have the highest responses, while the responses at background regions become very low. Based on such random contrasts, an optimization framework with pairwise binary terms is adopted to learn the saliency model that best separates salient targets and distractors by optimally integrating the cues from various subspaces. Experimental results on two public benchmarks show that the proposed approach outperforms 16 state-of-the-art methods in human fixation prediction.

  7. Heritable variation for latent inhibition and its correlation with reversal learning in honeybees (Apis mellifera).

    Science.gov (United States)

    Chandra, S B; Hosler, J S; Smith, B H

    2000-03-01

    Latent inhibition (LI) in honeybees (Apis mellifera) was studied by using a proboscis extension response conditioning procedure. Individual queens, drones, and workers differed in the degree to which they revealed LI. The authors hypothesized that individual differences would have a substantial genetic basis. Two sets of progeny were established by crossing virgin queens and individual drones, both of which had been selected for differential expression of inhibition. LI was stronger in the progeny from the queens and drones that had shown greater inhibition. The expression of LI was also dependent on environmental factors that are most likely associated with age, foraging experience outside of the colony, or both. Furthermore, there was a correlated response in the speed at which progeny reversed a learned discrimination of 2 odors. These genetic analyses may reveal underlying mechanisms that these 2 learning paradigms have in common.

  8. Perceptual Learning: 12-Month-Olds' Discrimination of Monkey Faces

    Science.gov (United States)

    Fair, Joseph; Flom, Ross; Jones, Jacob; Martin, Justin

    2012-01-01

    Six-month-olds reliably discriminate different monkey and human faces whereas 9-month-olds only discriminate different human faces. It is often falsely assumed that perceptual narrowing reflects a permanent change in perceptual abilities. In 3 experiments, ninety-six 12-month-olds' discrimination of unfamiliar monkey faces was examined. Following…

  9. Touch-screen visual reversal learning is mediated by value encoding and signal propagation in the orbitofrontal cortex.

    Science.gov (United States)

    Marquardt, Kristin; Sigdel, Rahul; Brigman, Jonathan L

    2017-03-01

    Behavioral inflexibility is a common symptom of neuropsychiatric disorders which can have a major detrimental impact on quality of life. While the orbitofrontal cortex (OFC) has been strongly implicated in behavioral flexibility in rodents across paradigms, our understanding of how the OFC mediates these behaviors is rapidly adapting. Here we examined neuronal activity during reversal learning by coupling in vivo electrophysiological recording with a mouse touch-screen learning paradigm to further elucidate the role of the OFC in updating reward value. Single unit and oscillatory activity was recorded during well-learned discrimination and 3 distinct phases of reversal (early, chance and well-learned). During touch-screen performance, OFC neuronal firing tracked rewarded responses following a previous rewarded choice when behavior was well learned, but shifted to primarily track repeated errors following a previous error in early reversal. Spike activity tracked rewarded choices independent of previous trial outcome during chance reversal, and returned to the initial pattern of reward response at criterion. Analysis of spike coupling to oscillatory local field potentials showed that less frequently occurring behaviors had significantly fewer neurons locked to any oscillatory frequency. Together, these data support the role of the OFC in tracking the value of individual choices to inform future responses and suggests that oscillatory signaling may be involved in propagating responses to increase or decrease the likelihood that action is taken in the future. They further support the use of touch-screen paradigms in preclinical studies to more closely model clinical approaches to measuring behavioral flexibility.

  10. Simultaneous and Sequential Feature Negative Discriminations: Elemental Learning and Occasion Setting in Human Pavlovian Conditioning

    Science.gov (United States)

    Baeyens, Frank; Vervliet, Bram; Vansteenwegen, Debora; Beckers, Tom; Hermans, Dirk; Eelen, Paul

    2004-01-01

    Using a conditioned suppression task, we investigated simultaneous (XA-/A+) vs. sequential (X [right arrow] A-/A+) Feature Negative (FN) discrimination learning in humans. We expected the simultaneous discrimination to result in X (or alternatively the XA configuration) becoming an inhibitor acting directly on the US, and the sequential…

  11. Teaching for Equity, Learning about Discrimination in a Meritocratic Society

    Science.gov (United States)

    Cruz, Fátima; Stake, Robert E.

    2012-01-01

    In this paper, we will examine key points for research attention in the effort to commit educational systems to equity education. We will examine the concepts of equity, equality and discrimination. We will give specific attention to the role of teacher educators. Teachers need to understand and to be able to see social discrimination in…

  12. Observations on auditory learning in amplitude- and frequency-modulation rate discrimination

    DEFF Research Database (Denmark)

    Hoffmann, Pablo F.

    2010-01-01

    . One of the key issues when designing such training systems is in the assessment of transfer of learning. In this study we present data on the learning of an auditory task involving sinusoidal amplitude- and frequency-modulated tones. Modulation rate discrimination thresholds were measured during pre......-training, training, a post-training stages. During training, listeners were divided into two groups; one group trained on amplitude-modulation rate discrimination and the other group trained on frequency-modulation rate discrimination. Results will be discussed in terms of their implications for training...

  13. Combining Generative and Discriminative Representation Learning for Lung CT Analysis With Convolutional Restricted Boltzmann Machines.

    Science.gov (United States)

    van Tulder, Gijs; de Bruijne, Marleen

    2016-05-01

    The choice of features greatly influences the performance of a tissue classification system. Despite this, many systems are built with standard, predefined filter banks that are not optimized for that particular application. Representation learning methods such as restricted Boltzmann machines may outperform these standard filter banks because they learn a feature description directly from the training data. Like many other representation learning methods, restricted Boltzmann machines are unsupervised and are trained with a generative learning objective; this allows them to learn representations from unlabeled data, but does not necessarily produce features that are optimal for classification. In this paper we propose the convolutional classification restricted Boltzmann machine, which combines a generative and a discriminative learning objective. This allows it to learn filters that are good both for describing the training data and for classification. We present experiments with feature learning for lung texture classification and airway detection in CT images. In both applications, a combination of learning objectives outperformed purely discriminative or generative learning, increasing, for instance, the lung tissue classification accuracy by 1 to 8 percentage points. This shows that discriminative learning can help an otherwise unsupervised feature learner to learn filters that are optimized for classification.

  14. Reduced autobiographical memory specificity is associated with impaired discrimination learning in anxiety disorder patients

    Science.gov (United States)

    Lenaert, Bert; Boddez, Yannick; Vervliet, Bram; Schruers, Koen; Hermans, Dirk

    2015-01-01

    Associative learning plays an important role in the development of anxiety disorders, but a thorough understanding of the variables that impact such learning is still lacking. We investigated whether individual differences in autobiographical memory specificity are related to discrimination learning and generalization. In an associative learning task, participants learned the association between two pictures of female faces and a non-aversive outcome. Subsequently, six morphed pictures functioning as generalization stimuli (GSs) were introduced. In a sample of healthy participants (Study 1), we did not find evidence for differences in discrimination learning as a function of memory specificity. In a sample of anxiety disorder patients (Study 2), individuals who were characterized by low memory specificity showed deficient discrimination learning relative to high specific individuals. In contrast to previous findings, results revealed no effect of memory specificity on generalization. These results indicate that impaired discrimination learning, previously shown in patients suffering from an anxiety disorder, may be—in part—due to limited memory specificity. Together, these studies emphasize the importance of incorporating cognitive variables in associative learning theories and their implications for the development of anxiety disorders. In addition, re-analyses of the data (Study 3) showed that patients suffering from panic disorder showed higher outcome expectancies in the presence of the stimulus that was never followed by an outcome during discrimination training, relative to patients suffering from other anxiety disorders and healthy participants. Because we used a neutral, non-aversive outcome (i.e., drawing of a lightning bolt), these data suggest that learning abnormalities in panic disorder may not be restricted to fear learning, but rather reflect a more general associative learning deficit that also manifests in fear irrelevant contexts. PMID

  15. The anterior claustrum and spatial reversal learning in rats.

    Science.gov (United States)

    Grasby, Katrina; Talk, Andrew

    2013-03-07

    The claustrum is a small structure of poorly understood function situated subcortically in the basal forebrain. The fact that it is extensively and reciprocally connected with the cerebral cortex has led to suggestions that it is involved in coordination of cortical activity. In this study, we created excitotoxic lesions to the anterior claustrum of rats and tested performance on three tasks that involve neural processing in one or more frontal and limbic cortical structures. We tested reversal learning and spatial working memory in a water maze and tested latent inhibition using conditioned taste aversion. Lesioned rats were not impaired at acquiring the initial location of the platform in a water maze, but were impaired at acquiring a switched location in the reversal phase. The lesioned rats also exhibited an increased rate of perseverance errors compared to control rats during reversal. Lesioned rats were not impaired in the working memory task or latent inhibition. These results indicate that cell loss in the claustrum may lead to deficits in behavioral flexibility, and are consistent with theories of claustral function that suggest it may help coordinate information necessary for at least some cortical-dependent tasks.

  16. Reversal Learning in Humans and Gerbils: Dynamic Control Network Facilitates Learning

    Directory of Open Access Journals (Sweden)

    Christian Jarvers

    2016-11-01

    Full Text Available Biologically plausible modeling of behavioral reinforcement learning tasks has seen great improvements over the past decades. Less work has been dedicated to tasks involving contingency reversals, i.e. tasks in which the original behavioral goal is reversed one or multiple times. The ability to adjust to such reversals is a key element of behavioral flexibility. Here, we investigate the neural mechanisms underlying contingency-reversal tasks. We first conduct experiments with humans and gerbils to demonstrate memory effects, including multiple reversals in which subjects (humans and animals show a faster learning rate when a previously learned contingency re-appears. Motivated by recurrent mechanisms of learning and memory for object categories, we propose a network architecture which involves reinforcement learning to steer an orienting system that monitors the success in reward acquisition. We suggest that a model sensory system provides feature representations which are further processed by category-related subnetworks which constitute a neural analog of expert networks. Categories are selected dynamically in a competitive field and predict the expected reward. Learning occurs in sequentialized phases to selectively focus the weight adaptation to synapses in the hierarchical network and modulate their weight changes by a global modulator signal. The orienting subsystem itself learns to bias the competition in the presence of continuous monotonic reward accumulation. In case of sudden changes in the discrepancy of predicted and acquired reward the activated motor category can be switched. We suggest that this subsystem is composed of a hierarchically organized network of dis-inhibitory mechanisms, dubbed a dynamic control network (DCN, which resembles components of the basal ganglia. The DCN selectively activates an expert network, corresponding to the current behavioral strategy. The trace of the accumulated reward is monitored such that

  17. Reversal Learning in Humans and Gerbils: Dynamic Control Network Facilitates Learning

    Science.gov (United States)

    Jarvers, Christian; Brosch, Tobias; Brechmann, André; Woldeit, Marie L.; Schulz, Andreas L.; Ohl, Frank W.; Lommerzheim, Marcel; Neumann, Heiko

    2016-01-01

    Biologically plausible modeling of behavioral reinforcement learning tasks has seen great improvements over the past decades. Less work has been dedicated to tasks involving contingency reversals, i.e., tasks in which the original behavioral goal is reversed one or multiple times. The ability to adjust to such reversals is a key element of behavioral flexibility. Here, we investigate the neural mechanisms underlying contingency-reversal tasks. We first conduct experiments with humans and gerbils to demonstrate memory effects, including multiple reversals in which subjects (humans and animals) show a faster learning rate when a previously learned contingency re-appears. Motivated by recurrent mechanisms of learning and memory for object categories, we propose a network architecture which involves reinforcement learning to steer an orienting system that monitors the success in reward acquisition. We suggest that a model sensory system provides feature representations which are further processed by category-related subnetworks which constitute a neural analog of expert networks. Categories are selected dynamically in a competitive field and predict the expected reward. Learning occurs in sequentialized phases to selectively focus the weight adaptation to synapses in the hierarchical network and modulate their weight changes by a global modulator signal. The orienting subsystem itself learns to bias the competition in the presence of continuous monotonic reward accumulation. In case of sudden changes in the discrepancy of predicted and acquired reward the activated motor category can be switched. We suggest that this subsystem is composed of a hierarchically organized network of dis-inhibitory mechanisms, dubbed a dynamic control network (DCN), which resembles components of the basal ganglia. The DCN selectively activates an expert network, corresponding to the current behavioral strategy. The trace of the accumulated reward is monitored such that large sudden

  18. Learning-induced reversal of the effect of noradrenalin on the postburst AHP.

    Science.gov (United States)

    Brosh, Inbar; Rosenblum, Kobi; Barkai, Edi

    2006-10-01

    Pyramidal neurons in the piriform cortex from olfactory-discrimination-trained rats have reduced postburst afterhyperpolarization (AHP), for 3 days after learning, and are thus more excitable during this period. Such AHP reduction is caused by decreased conductance of one or more of the calcium-dependent potassium currents, I(AHP) and sI(AHP), that mediate the medium and slow AHPs. In this study, we examined which potassium current is reduced by learning and how the effect of noradrenalin (NE) on neuronal excitability is modified by such reduction. The small conductance (SK) channels inhibitor, apamin, that selectively blocks I(A)(HP), reduced the AHP in neurons from trained, naïve, and pseudotrained rats to a similar extent, thus maintaining the difference in AHP amplitude between neurons from trained rats and controls. In addition, the protein expression level of the SK1, SK2, and SK3 channels was also similar in all groups. NE, which was shown to enhance I(AHP) while suppressing (S)I(AHP), reduced the AHP in neurons from controls but enhanced the AHP in neurons from trained rats. Our data show that learning-induced enhancement of neuronal excitability is not the result of reduction in the I(AHP) current. Thus it is probably mediated by reduction in conductance of the other calcium-dependent potassium current, sI(AHP). Consequently, the effect of NE on neuronal excitability is reversed. We propose that the change in the effect of NE after learning may act to counterbalance learning-induced hyperexcitability and preserve the piriform cortex ability to subserve olfactory learning.

  19. Carrion crows learn to discriminate between calls of reliable and unreliable conspecifics.

    Science.gov (United States)

    Wascher, Claudia A F; Hillemann, Friederike; Canestrari, Daniela; Baglione, Vittorio

    2015-09-01

    Partner choice on the basis of an individual's reliability is expected to stabilize social interactions. In this experiment, we tested whether carrion crows (Corvus corone corone) learn to differentiate between calls of reliable or unreliable individuals. Crows were kept in an aviary that comprised four visually but not acoustically isolated compartments, separated by a central room. In an association phase, a dead crow placed in the central compartment was visible only to one of the four crow groups, whilst alert calls of a conspecific were played back. Therefore, these calls were reliable for that group, but unreliable for the three other groups. The procedure was repeated, using a different reliable caller for each group. In two test sessions, 1 month apart, reliable and unreliable model individuals were played back, but no dead crow was presented. We quantified birds' attention behaviour and the number of vocalisations emitted. In the association phase, crows were more attentive towards the reliable compared with the unreliable stimuli and called more in response to reliable compared to unreliable individuals. In the test and repeat phase, attention behaviour did not differ between reliability conditions, but the pattern of vocal behaviour reversed, with crows calling less frequent when listening to reliable compared with unreliable calls. Vocal responses of crows suggest that they can discriminate between reliable and unreliable callers.

  20. Differential involvement of hippocampal calcineurin during learning and reversal learning in a Y-maze task

    NARCIS (Netherlands)

    Havekes, Robbert; Nijholt, Ingrid M.; Luiten, Paul G. M.; Van der Zee, Eddy A.

    2006-01-01

    The regulation and function of the calcium-dependent phosphatase calcineurin (CaN, protein phosphatase 2B) in learning and memory remain unclear, although recent work indicates that CaN may play a differential role in training and reversal training. To gain more insight into the involvement of CaN

  1. Differential involvement of hippocampal calcineurin during learning and reversal learning in a Y-maze task

    NARCIS (Netherlands)

    Havekes, Robbert; Nijholt, Ingrid M.; Luiten, Paul G. M.; Van der Zee, Eddy A.

    2006-01-01

    The regulation and function of the calcium-dependent phosphatase calcineurin (CaN, protein phosphatase 2B) in learning and memory remain unclear, although recent work indicates that CaN may play a differential role in training and reversal training. To gain more insight into the involvement of CaN i

  2. Task discrimination from myoelectric activity: a learning scheme for EMG-based interfaces.

    Science.gov (United States)

    Liarokapis, Minas V; Artemiadis, Panagiotis K; Kyriakopoulos, Kostas J

    2013-06-01

    A learning scheme based on Random Forests is used to discriminate the task to be executed using only myoelectric activity from the upper limb. Three different task features can be discriminated: subspace to move towards, object to be grasped and task to be executed (with the object). The discrimination between the different reach to grasp movements is accomplished with a random forests classifier, which is able to perform efficient features selection, helping us to reduce the number of EMG channels required for task discrimination. The proposed scheme can take advantage of both a classifier and a regressor that cooperate advantageously to split the task space, providing better estimation accuracy with task-specific EMG-based motion decoding models, as reported in [1] and [2]. The whole learning scheme can be used by a series of EMG-based interfaces, that can be found in rehabilitation cases and neural prostheses.

  3. Conditional discrimination and reversal in amnesia subsequent to hypoxic brain injury or anterior communicating artery aneurysm rupture

    Science.gov (United States)

    Myers, C.E.; DeLuca, J.; Hopkins, R.O.; Gluck, M.A.

    2007-01-01

    Human anterograde amnesia can develop following bilateral damage to the hippocampus and medial temporal lobes, as in hypoxic brain injury, or following damage to the basal forebrain, as following anterior communicating artery (ACoA) aneurysm rupture. In both cases, the mnestic deficit may be similar when assessed by standard neuropsychological measures. However, animal and computational models suggest that there are qualitative differences in the pattern of impaired and spared memory abilities following damage to hippocampus versus basal forebrain. Here, we show such a dissociation in human amnesia using a single two-stage task, involving conditional discrimination and reversal. Consistent with a prior study, 10 individuals with anterograde amnesia subsequent to hypoxic brain injury were spared on acquisition but impaired at reversal. However, 10 individuals with amnesia subsequent to ACoA aneurysm showed the opposite pattern of impaired acquisition but spared reversal. The differences between groups cannot be easily ascribed to severity of mnestic or cognitive deficit, since the two amnesic groups performed similarly on neuropsychological tests of memory, intelligence and attention. The results illustrate qualitative differences in memory impairments in hypoxic and ACoA amnesics and highlight the importance of considering etiology in evaluating mnemonic deficits in amnesic populations. PMID:15885718

  4. Challenges of organizational learning: perpetuation of discrimination against employees with disabilities.

    Science.gov (United States)

    Wooten, Lynn Perry; James, Erika Hayes

    2005-01-01

    This article examines why organizations struggle with learning how to prevent discrimination against their employees with disabilities. To explore this issue, qualitative archival data were collected and analyzed from 53 Americans with Disabilities Act (ADA) lawsuits filed against 44 organizations. Theoretical analysis of the qualitative data suggests that several organizationally based learning theories explain the difficulty organizations have with creating a disability-friendly work environment. These barriers to learning are embedded in complex defense mechanisms and discriminatory organizational routines. Furthermore, organizations have difficulties engaging in higher-order and vicarious learning. We conclude the article with examples of successful learning practices as they relate to barriers identified in the qualitative analysis.

  5. Multiple Kernel Learning in Fisher Discriminant Analysis for Face Recognition

    Directory of Open Access Journals (Sweden)

    Xiao-Zhang Liu

    2013-02-01

    Full Text Available Recent applications and developments based on support vector machines (SVMs have shown that using multiple kernels instead of a single one can enhance classifier performance. However, there are few reports on performance of the kernel‐based Fisher discriminant analysis (kernel‐based FDA method with multiple kernels. This paper proposes a multiple kernel construction method for kernel‐based FDA. The constructed kernel is a linear combination of several base kernels with a constraint on their weights. By maximizing the margin maximization criterion (MMC, we present an iterative scheme for weight optimization. The experiments on the FERET and CMU PIE face databases show that, our multiple kernel Fisher discriminant analysis (MKFD achieves high recognition performance, compared with single‐kernel‐based FDA. The experiments also show that the constructed kernel relaxes parameter selection for kernel‐based FDA to some extent.

  6. Learning Discriminative Bayesian Networks from High-Dimensional Continuous Neuroimaging Data.

    Science.gov (United States)

    Zhou, Luping; Wang, Lei; Liu, Lingqiao; Ogunbona, Philip; Shen, Dinggang

    2016-11-01

    Due to its causal semantics, Bayesian networks (BN) have been widely employed to discover the underlying data relationship in exploratory studies, such as brain research. Despite its success in modeling the probability distribution of variables, BN is naturally a generative model, which is not necessarily discriminative. This may cause the ignorance of subtle but critical network changes that are of investigation values across populations. In this paper, we propose to improve the discriminative power of BN models for continuous variables from two different perspectives. This brings two general discriminative learning frameworks for Gaussian Bayesian networks (GBN). In the first framework, we employ Fisher kernel to bridge the generative models of GBN and the discriminative classifiers of SVMs, and convert the GBN parameter learning to Fisher kernel learning via minimizing a generalization error bound of SVMs. In the second framework, we employ the max-margin criterion and build it directly upon GBN models to explicitly optimize the classification performance of the GBNs. The advantages and disadvantages of the two frameworks are discussed and experimentally compared. Both of them demonstrate strong power in learning discriminative parameters of GBNs for neuroimaging based brain network analysis, as well as maintaining reasonable representation capacity. The contributions of this paper also include a new Directed Acyclic Graph (DAG) constraint with theoretical guarantee to ensure the graph validity of GBN.

  7. The Role of the Orbitofrontal Cortex in Human Discrimination Learning

    Science.gov (United States)

    Chase, Henry W.; Clark, Luke; Myers, Catherine E.; Gluck, Mark A.; Sahakian, Barbara J.; Bullmore, Edward T.; Robbins, Trevor W.

    2008-01-01

    Several lines of evidence implicate the prefrontal cortex in learning but there is little evidence from studies of human lesion patients to demonstrate the critical role of this structure. To this end, we tested patients with lesions of the frontal lobe (n = 36) and healthy controls (n = 35) on two learning tasks: the weather prediction task…

  8. No trade-off between learning speed and associative flexibility in bumblebees: a reversal learning test with multiple colonies.

    Directory of Open Access Journals (Sweden)

    Nigel E Raine

    Full Text Available Potential trade-offs between learning speed and memory-related performance could be important factors in the evolution of learning. Here, we test whether rapid learning interferes with the acquisition of new information using a reversal learning paradigm. Bumblebees (Bombus terrestris were trained to associate yellow with a floral reward. Subsequently the association between colour and reward was reversed, meaning bees then had to learn to visit blue flowers. We demonstrate that individuals that were fast to learn yellow as a predictor of reward were also quick to reverse this association. Furthermore, overnight memory retention tests suggest that faster learning individuals are also better at retaining previously learned information. There is also an effect of relatedness: colonies whose workers were fast to learn the association between yellow and reward also reversed this association rapidly. These results are inconsistent with a trade-off between learning speed and the reversal of a previously made association. On the contrary, they suggest that differences in learning performance and cognitive (behavioural flexibility could reflect more general differences in colony learning ability. Hence, this study provides additional evidence to support the idea that rapid learning and behavioural flexibility have adaptive value.

  9. The GABAergic Anterior Paired Lateral Neurons Facilitate Olfactory Reversal Learning in "Drosophila"

    Science.gov (United States)

    Wu, Yanying; Ren, Qingzhong; Li, Hao; Guo, Aike

    2012-01-01

    Reversal learning has been widely used to probe the implementation of cognitive flexibility in the brain. Previous studies in monkeys identified an essential role of the orbitofrontal cortex (OFC) in reversal learning. However, the underlying circuits and molecular mechanisms are poorly understood. Here, we use the T-maze to investigate the neural…

  10. The GABAergic Anterior Paired Lateral Neurons Facilitate Olfactory Reversal Learning in "Drosophila"

    Science.gov (United States)

    Wu, Yanying; Ren, Qingzhong; Li, Hao; Guo, Aike

    2012-01-01

    Reversal learning has been widely used to probe the implementation of cognitive flexibility in the brain. Previous studies in monkeys identified an essential role of the orbitofrontal cortex (OFC) in reversal learning. However, the underlying circuits and molecular mechanisms are poorly understood. Here, we use the T-maze to investigate the neural…

  11. Paradoxical reversal learning enhancement by stress or prefrontal cortical damage: rescue with BDNF.

    Science.gov (United States)

    Graybeal, Carolyn; Feyder, Michael; Schulman, Emily; Saksida, Lisa M; Bussey, Timothy J; Brigman, Jonathan L; Holmes, Andrew

    2011-11-06

    Stress affects various forms of cognition. We found that moderate stress enhanced late reversal learning in a mouse touchscreen-based choice task. Ventromedial prefrontal cortex (vmPFC) lesions mimicked the effect of stress, whereas orbitofrontal and dorsolateral striatal lesions impaired reversal. Stress facilitation of reversal was prevented by BDNF infusion into the vmPFC. These findings suggest a mechanism by which stress-induced vmPFC dysfunction disinhibits learning by alternate (for example, striatal) systems.

  12. Paradoxical reversal learning enhancement by stress or prefrontal cortical damage: rescue with BDNF

    OpenAIRE

    Graybeal, Carolyn; Feyder, Michael; Schulman, Emily; Saksida, Lisa M.; Bussey, Timothy J.; Brigman, Jonathan L.; Holmes, Andrew

    2011-01-01

    Stress often has deleterious effects on cognition. We show that moderate stress enhanced late reversal learning in a mouse touchscreen-based choice task. Ventromedial prefrontal cortex (vmPFC) lesions mimicked the effects of stress, while orbitofrontal (OFC) and dorsolateral striatal (DLS) lesions impaired reversal. Stress-facilitation of reversal was prevented by BDNF infusion into the vmPFC. These findings suggest a mechanism in which stress-induced vmPFC dysfunction disinhibits learning by...

  13. Bidirectional Regulation of Innate and Learned Behaviors That Rely on Frequency Discrimination by Cortical Inhibitory Neurons.

    Directory of Open Access Journals (Sweden)

    Mark Aizenberg

    2015-12-01

    Full Text Available The ability to discriminate tones of different frequencies is fundamentally important for everyday hearing. While neurons in the primary auditory cortex (AC respond differentially to tones of different frequencies, whether and how AC regulates auditory behaviors that rely on frequency discrimination remains poorly understood. Here, we find that the level of activity of inhibitory neurons in AC controls frequency specificity in innate and learned auditory behaviors that rely on frequency discrimination. Photoactivation of parvalbumin-positive interneurons (PVs improved the ability of the mouse to detect a shift in tone frequency, whereas photosuppression of PVs impaired the performance. Furthermore, photosuppression of PVs during discriminative auditory fear conditioning increased generalization of conditioned response across tone frequencies, whereas PV photoactivation preserved normal specificity of learning. The observed changes in behavioral performance were correlated with bidirectional changes in the magnitude of tone-evoked responses, consistent with predictions of a model of a coupled excitatory-inhibitory cortical network. Direct photoactivation of excitatory neurons, which did not change tone-evoked response magnitude, did not affect behavioral performance in either task. Our results identify a new function for inhibition in the auditory cortex, demonstrating that it can improve or impair acuity of innate and learned auditory behaviors that rely on frequency discrimination.

  14. Different parameters support generalization and discrimination learning in Drosophila at the flight simulator.

    Science.gov (United States)

    Brembs, Björn; Hempel de Ibarra, Natalie

    2006-01-01

    We have used a genetically tractable model system, the fruit fly Drosophila melanogaster to study the interdependence between sensory processing and associative processing on learning performance. We investigated the influence of variations in the physical and predictive properties of color stimuli in several different operant-conditioning procedures on the subsequent learning performance. These procedures included context and stimulus generalization as well as color, compound, and conditional discrimination (colors and patterns). A surprisingly complex dependence of the learning performance on the colors' physical and predictive properties emerged, which was clarified by taking into account the fly-subjective perception of the color stimuli. Based on estimates of the stimuli's color and brightness values, we propose that the different tasks are supported by different parameters of the color stimuli; generalization occurs only if the chromaticity is sufficiently similar, whereas discrimination learning relies on brightness differences.

  15. Neuromagnetic fields reveal cortical plasticity when learning an auditory discrimination task.

    Science.gov (United States)

    Cansino, S; Williamson, S J

    1997-08-01

    Auditory evoked neuromagnetic fields of the primary and association auditory cortices were recorded while subjects learned to discriminate small differences in frequency and intensity between two consecutive tones. When discrimination was no better than chance, evoked field patterns across the scalp manifested no significant differences between correct and incorrect responses. However, when performance was correct on at least 75% of the trials, the spatial pattern of magnetic field differed significantly between correct and incorrect responses during the first 70 ms following the onset of the second tone. In this respect, the magnetic field pattern predicted when the subject would make an incorrect judgment more than 100 ms prior to indicating the judgment by a button press. One subject improved discrimination for much smaller differences between stimuli after 200 h of training. Evidence of cortical plasticity with improved discrimination is provided by an accompanying decrease of the relative magnetic field amplitude of the 100 ms response components in the primary and association auditory cortices.

  16. Knockdown of Nurr1 in the rat hippocampus: Implications to spatial discrimination learning and memory

    OpenAIRE

    2006-01-01

    Nurr1 expression is up-regulated in the brain following associative learning experiences, but its relevance to cognitive processes remains unclear. In these studies, rats initially received bilateral hippocampal infusions of control or antisense oligodeoxynucleotides (ODNs) 1 h prior to training in a holeboard spatial discrimination task. Such pre-training infusions of nurr1 antisense ODNs caused a moderate effect in learning the task and also impaired LTM tested 7 d later. In a second experi...

  17. Knockdown of Nurr1 in the rat hippocampus: Implications to spatial discrimination learning and memory

    OpenAIRE

    Colón-Cesario, Wanda I.; Martínez-Montemayor, Michelle M.; Morales, Sohaira; Félix, Jahaira; Cruz, Juan; Adorno, Monique; Pereira, Lixmar; Colón, Nydia; Maldonado-Vlaar, Carmen S.; Peña de Ortiz, Sandra

    2006-01-01

    Nurr1 expression is up-regulated in the brain following associative learning experiences, but its relevance to cognitive processes remains unclear. In these studies, rats initially received bilateral hippocampal infusions of control or antisense oligodeoxynucleotides (ODNs) 1 h prior to training in a holeboard spatial discrimination task. Such pre-training infusions of nurr1 antisense ODNs caused a moderate effect in learning the task and also impaired LTM tested 7 d later. In a second experi...

  18. Combining generative and discriminative representation learning for lung CT analysis with convolutional restricted Boltzmann machines

    DEFF Research Database (Denmark)

    van Tulder, Gijs; de Bruijne, Marleen

    2016-01-01

    unlabeled data, but does not necessarily produce features that are optimal for classification. In this paper we propose the convolutional classification restricted Boltzmann machine, which combines a generative and a discriminative learning objective. This allows it to learn filters that are good both......The choice of features greatly influences the performance of a tissue classification system. Despite this, many systems are built with standard, predefined filter banks that are not optimized for that particular application. Representation learning methods such as restricted Boltzmann machines may...... outperform these standard filter banks because they learn a feature description directly from the training data. Like many other representation learning methods, restricted Boltzmann machines are unsupervised and are trained with a generative learning objective; this allows them to learn representations from...

  19. Learning discriminative classification models for grading anal intraepithelial neoplasia

    Directory of Open Access Journals (Sweden)

    Kainz Philipp

    2016-09-01

    Full Text Available Grading intraepithelial neoplasia is crucial to derive an accurate estimate of pre-cancerous stages and is currently performed by pathologists assessing histopathological images. Inter- and intra-observer variability can significantly be reduced, when reliable, quantitative image analysis is introduced into diagnostic processes. On a challenging dataset, we evaluated the potential of learning a classifier to grade anal intraepitelial neoplasia. Support vector machines were trained on images represented by fractal and statistical features. We show that pursuing a learning-based grading strategy yields highly reliable results. Compared to existing methods, the proposed method outperformed them by a significant margin.

  20. A stimulus-location effect in contingency-governed, but not rule-based, discrimination learning.

    Science.gov (United States)

    Meier, Christina; Lea, Stephen E G; McLaren, Ian P L

    2016-04-01

    We tested pigeons' acquisition of a conditional discrimination task between colored grating stimuli that included choosing 1 of 2 response keys, which either appeared as white keys to the left and right of the discriminative stimulus, or were replicas of the stimulus. Pigeons failed to acquire the discrimination when the response keys were white disks but succeeded when directly responding to a replica of the stimulus. These results highlight how conditioning processes shape learning in pigeons: The results can be accounted for by supposing that, when pigeons were allowed to respond directly toward the stimulus, learning was guided by classical conditioning, but that responding to white keys demanded instrumental learning, which impaired task acquisition for pigeons. In contrast, humans completing the same paradigm showed no differential learning success depending on whether figure or position indicated the correct key. However, only participants who could state the underlying discrimination rule acquired the task, which implies that human performance in this situation relied on the deduction and application of task rules instead of associative processes.

  1. Discrimination of Breast Cancer with Microcalcifications on Mammography by Deep Learning.

    Science.gov (United States)

    Wang, Jinhua; Yang, Xi; Cai, Hongmin; Tan, Wanchang; Jin, Cangzheng; Li, Li

    2016-06-07

    Microcalcification is an effective indicator of early breast cancer. To improve the diagnostic accuracy of microcalcifications, this study evaluates the performance of deep learning-based models on large datasets for its discrimination. A semi-automated segmentation method was used to characterize all microcalcifications. A discrimination classifier model was constructed to assess the accuracies of microcalcifications and breast masses, either in isolation or combination, for classifying breast lesions. Performances were compared to benchmark models. Our deep learning model achieved a discriminative accuracy of 87.3% if microcalcifications were characterized alone, compared to 85.8% with a support vector machine. The accuracies were 61.3% for both methods with masses alone and improved to 89.7% and 85.8% after the combined analysis with microcalcifications. Image segmentation with our deep learning model yielded 15, 26 and 41 features for the three scenarios, respectively. Overall, deep learning based on large datasets was superior to standard methods for the discrimination of microcalcifications. Accuracy was increased by adopting a combinatorial approach to detect microcalcifications and masses simultaneously. This may have clinical value for early detection and treatment of breast cancer.

  2. Knockdown of Nurr1 in the Rat Hippocampus: Implications to Spatial Discrimination Learning and Memory

    Science.gov (United States)

    Colon-Cesario, Wanda I.; Martinez-Montemayor, Michelle M.; Morales, Sohaira; Felix, Jahaira; Cruz, Juan; Adorno, Monique; Pereira, Lixmar; Colon, Nydia; Maldonado-Vlaar, Carmen S.; Pena de Ortiz, Sandra

    2006-01-01

    Nurr1 expression is up-regulated in the brain following associative learning experiences, but its relevance to cognitive processes remains unclear. In these studies, rats initially received bilateral hippocampal infusions of control or antisense oligodeoxynucleotides (ODNs) 1 hour prior to training in a holeboard spatial discrimination task. Such…

  3. An Experimental Investigation of the Effect of Worry on Responses to a Discrimination Learning Task

    Science.gov (United States)

    Salters-Pedneault, Kristalyn; Suvak, Michael; Roemer, Lizabeth

    2008-01-01

    The current study examined the impact of both the tendency to worry (trait worry) and the process of worry (state worry) on subsequent behavioral responding in a schedule discrimination learning task. High and low trait worriers were randomly assigned to a state worry or relaxation incubation condition and completed a test of executive functioning…

  4. Knockdown of Nurr1 in the Rat Hippocampus: Implications to Spatial Discrimination Learning and Memory

    Science.gov (United States)

    Colon-Cesario, Wanda I.; Martinez-Montemayor, Michelle M.; Morales, Sohaira; Felix, Jahaira; Cruz, Juan; Adorno, Monique; Pereira, Lixmar; Colon, Nydia; Maldonado-Vlaar, Carmen S.; Pena de Ortiz, Sandra

    2006-01-01

    Nurr1 expression is up-regulated in the brain following associative learning experiences, but its relevance to cognitive processes remains unclear. In these studies, rats initially received bilateral hippocampal infusions of control or antisense oligodeoxynucleotides (ODNs) 1 hour prior to training in a holeboard spatial discrimination task. Such…

  5. AX+/BX- Discrimination Learning in the Fear-Potentiated Startle Paradigm in Monkeys

    Science.gov (United States)

    Winslow, James T.; Noble, Pamela L.; Davis, Michael

    2008-01-01

    Individuals with anxiety disorders often do not respond to safety signals and hence continue to be afraid and anxious. Consequently, it is important to develop paradigms in animals that can directly study brain systems involved in learning about, and responding to, safety signals. We previously developed a discrimination procedure in rats of the…

  6. Upregulation of Neurotrophic Factors Selectively in Frontal Cortex in Response to Olfactory Discrimination Learning

    Directory of Open Access Journals (Sweden)

    Ari Naimark

    2007-01-01

    Full Text Available We have previously shown that olfactory discrimination learning is accompanied by several forms of long-term enhancement in synaptic connections between layer II pyramidal neurons selectively in the piriform cortex. This study sought to examine whether the previously demonstrated olfactory-learning-task-induced modifications are preceded by suitable changes in the expression of mRNA for neurotrophic factors and in which brain areas this occurs. Rats were trained to discriminate positive cues in pair of odors for a water reward. The relationship between the learning task and local levels of mRNA for brain-derived neurotrophic factor, tyrosine kinase B, nerve growth factor, and neurotrophin-3 in the frontal cortex, hippocampal subregions, and other regions were assessed 24 hours post olfactory learning. The olfactory discrimination learning activated production of endogenous neurotrophic factors and induced their signal transduction in the frontal cortex, but not in other brain areas. These findings suggest that different brain areas may be preferentially involved in different learning/memory tasks.

  7. Untutored discrimination training on paired cell images influences visual learning in cytopathology.

    Science.gov (United States)

    Evered, Andrew; Walker, Darren; Watt, Andrew A; Perham, Nick

    2014-03-01

    Cytologists must learn how to discriminate cells that might be visually very similar but have different neoplastic potential. The mechanism by which trainees learn this task is poorly researched and is the focus of the current investigation. Cognitive science offers a theoretical platform from which to design meaningful experiments that could lead to novel training strategies. The interpretation of a cell image is a category-discrimination task, and the process by which discrimination improves with practice is called perceptual learning. The study authors operationalized this concept by training 150 naive observers on paired cell images without providing explicit tuition, employing cervical cytology as a model system. Six strategies were tested, which differed according to the diagnostic category and level of interpretive difficulty of each image. Participants were tested before and after training to determine the extent to which visual learning had occurred. Diagnostic accuracy improved for participants who were trained on normal/abnormal image pairs in which at least one member of the pair was "easy" to interpret (P image pairs were drawn from the same diagnostic category or when both members of the pair were "difficult" to interpret (P > .05). Training on paired cell images without explicit tuition can be an efficient and effective means of visual learning in cytopathology, but only if care is taken to avoid image pairs from category boundaries. Training on same-category image pairs is ineffective. This study is a step toward the development of perceptual learning modules for cytopathology. © 2013 American Cancer Society.

  8. A one-step reverse transcription loop-mediated isothermal amplification for detection and discrimination of infectious bursal disease virus

    Directory of Open Access Journals (Sweden)

    Qi Xiaole

    2011-03-01

    Full Text Available Abstract Background Infectious bursal disease (IBD is a highly contagious immunosuppressive disease in young chickens caused by infectious bursal disease virus (IBDV. It causes huge economic losses to the poultry industry. The objective of this study is to develop a loop-mediated isothermal amplification (LAMP method for the detection and discrimination of IBDV. Results In this study, we applied reverse transcription loop-mediated isothermal amplification (RT-LAMP to detect IBDV in one simple step and further identified the very virulent strain from non-vvIBDVs with a simply post-amplification restriction enzyme analysis. Based on sequence analysis, a set of two inner, two outer and two loop primers were designed to target the VP5 gene and they showed great specificity with no cross reaction to the other common avian pathogens. The detection limit determined by both color change inspection and agarose gel electrophoresis was 28 copies viral RNA, which was almost as sensitive as a real-time RT-PCR previous developed in our laboratory. We also identified a unique Tfi I restriction site located exclusively in non-vvIBDVs, so very virulent strain could be distinguished from current vaccine strains. By screening a panel of clinical specimens, results showed that this method is high feasible in clinical settings, and it obtained results 100% correlated with real-time RT-PCR. Conclusion RT-LAMP is a rapid, simple and sensitive assay. In combination with the Tfi I restriction analysis, this method holds great promises not only in laboratory detection and discrimination of IBDV but also in large scale field and clinical studies.

  9. Learning and Visualizing Modulation Discriminative Radio Signal Features

    Science.gov (United States)

    2016-09-01

    valued temporal domain radio signals. We propose a method for accomplishing online semi-supervised learning with a tied- weight convolutional...reduction of X. Additionally, if φ is parameterized by a weight matrix W and ψ = W T , this method is known as weight tying and has the desirable...waveforms’ input. This binary data is modulated as in-phase and quadrature (I/Q) samples using each of six methods : on-off keying (OOK), Gaussian

  10. Frequency discrimination in children: perception, learning and attention.

    Science.gov (United States)

    Moore, David R; Ferguson, Melanie A; Halliday, Lorna F; Riley, Alison

    2008-04-01

    It is generally believed that both sensory immaturity and inattention contribute to the poor listening of some children. However, the relative contribution of each factor, within and between individuals, and the nature of the inattention are poorly understood. In three experiments we examined the threshold and response variability of 6-11 y.o. children on pure tone frequency discrimination (FD) tasks. We first confirmed that younger children had both higher thresholds and greater within- and between-listener variability than older children and adults. Higher thresholds were mostly attributed to high response variability due to poor sustained attention. We next compared performance on the auditory FD task with that on visual spatial FD. No correlation was found between the thresholds or variability of individuals on the two tasks, suggesting involvement of modality-specific attention. Finally, we found lower thresholds for 8-9 y.o. children performing auditory FD training in a classroom than in the laboratory, possibly due to training session length or to a more familiar, motivating and focussed training environment. The adult-like performance of many younger children at times during their testing or training, together with the high response variability of immature performers, suggested that most elevated FD thresholds in children are due to inattention.

  11. Supervised orthogonal discriminant subspace projects learning for face recognition.

    Science.gov (United States)

    Chen, Yu; Xu, Xiao-Hong

    2014-02-01

    In this paper, a new linear dimension reduction method called supervised orthogonal discriminant subspace projection (SODSP) is proposed, which addresses high-dimensionality of data and the small sample size problem. More specifically, given a set of data points in the ambient space, a novel weight matrix that describes the relationship between the data points is first built. And in order to model the manifold structure, the class information is incorporated into the weight matrix. Based on the novel weight matrix, the local scatter matrix as well as non-local scatter matrix is defined such that the neighborhood structure can be preserved. In order to enhance the recognition ability, we impose an orthogonal constraint into a graph-based maximum margin analysis, seeking to find a projection that maximizes the difference, rather than the ratio between the non-local scatter and the local scatter. In this way, SODSP naturally avoids the singularity problem. Further, we develop an efficient and stable algorithm for implementing SODSP, especially, on high-dimensional data set. Moreover, the theoretical analysis shows that LPP is a special instance of SODSP by imposing some constraints. Experiments on the ORL, Yale, Extended Yale face database B and FERET face database are performed to test and evaluate the proposed algorithm. The results demonstrate the effectiveness of SODSP.

  12. Effects of acute restraint stress on set-shifting and reversal learning in male rats.

    Science.gov (United States)

    Thai, Chester A; Zhang, Ying; Howland, John G

    2013-03-01

    Exposure to acute stress alters cognition; however, few studies have examined the effects of acute stress on executive functions such as behavioral flexibility. The goal of the present experiments was to determine the effects of acute periods of stress on two distinct forms of behavioral flexibility: set-shifting and reversal learning. Male Sprague-Dawley rats were trained and tested in an operant-chamber-based task. Some of the rats were exposed to acute restraint stress (30 min) immediately before either the set-shifting test day or the reversal learning test day. Acute stress had no effect on set-shifting, but it significantly facilitated reversal learning, as assessed by both trials to criterion and total errors. In a second experiment, the roles of glucocorticoid (GR) and mineralocorticoid receptors (MR) in the acute-stress-induced facilitation of reversal learning were examined. Systemic administration of the GR-selective antagonist RU38486 (10 mg/kg) or the MR-selective antagonist spironolactone (50 mg/kg) 30 min prior to acute stress failed to block the facilitation on reversal learning. The present results demonstrate a dissociable effect of acute stress on set-shifting and reversal learning and suggest that the facilitation of reversal learning by acute stress may be mediated by factors other than corticosterone.

  13. A perceptual learning deficit in Chinese developmental dyslexia as revealed by visual texture discrimination training.

    Science.gov (United States)

    Wang, Zhengke; Cheng-Lai, Alice; Song, Yan; Cutting, Laurie; Jiang, Yuzheng; Lin, Ou; Meng, Xiangzhi; Zhou, Xiaolin

    2014-08-01

    Learning to read involves discriminating between different written forms and establishing connections with phonology and semantics. This process may be partially built upon visual perceptual learning, during which the ability to process the attributes of visual stimuli progressively improves with practice. The present study investigated to what extent Chinese children with developmental dyslexia have deficits in perceptual learning by using a texture discrimination task, in which participants were asked to discriminate the orientation of target bars. Experiment l demonstrated that, when all of the participants started with the same initial stimulus-to-mask onset asynchrony (SOA) at 300 ms, the threshold SOA, adjusted according to response accuracy for reaching 80% accuracy, did not show a decrement over 5 days of training for children with dyslexia, whereas this threshold SOA steadily decreased over the training for the control group. Experiment 2 used an adaptive procedure to determine the threshold SOA for each participant during training. Results showed that both the group of dyslexia and the control group attained perceptual learning over the sessions in 5 days, although the threshold SOAs were significantly higher for the group of dyslexia than for the control group; moreover, over individual participants, the threshold SOA negatively correlated with their performance in Chinese character recognition. These findings suggest that deficits in visual perceptual processing and learning might, in part, underpin difficulty in reading Chinese.

  14. Label consistent K-SVD: learning a discriminative dictionary for recognition.

    Science.gov (United States)

    Jiang, Zhuolin; Lin, Zhe; Davis, Larry S

    2013-11-01

    A label consistent K-SVD (LC-KSVD) algorithm to learn a discriminative dictionary for sparse coding is presented. In addition to using class labels of training data, we also associate label information with each dictionary item (columns of the dictionary matrix) to enforce discriminability in sparse codes during the dictionary learning process. More specifically, we introduce a new label consistency constraint called "discriminative sparse-code error" and combine it with the reconstruction error and the classification error to form a unified objective function. The optimal solution is efficiently obtained using the K-SVD algorithm. Our algorithm learns a single overcomplete dictionary and an optimal linear classifier jointly. The incremental dictionary learning algorithm is presented for the situation of limited memory resources. It yields dictionaries so that feature points with the same class labels have similar sparse codes. Experimental results demonstrate that our algorithm outperforms many recently proposed sparse-coding techniques for face, action, scene, and object category recognition under the same learning conditions.

  15. Discriminative Nonlinear Analysis Operator Learning: When Cosparse Model Meets Image Classification

    Science.gov (United States)

    Wen, Zaidao; Hou, Biao; Jiao, Licheng

    2017-07-01

    Linear synthesis model based dictionary learning framework has achieved remarkable performances in image classification in the last decade. Behaved as a generative feature model, it however suffers from some intrinsic deficiencies. In this paper, we propose a novel parametric nonlinear analysis cosparse model (NACM) with which a unique feature vector will be much more efficiently extracted. Additionally, we derive a deep insight to demonstrate that NACM is capable of simultaneously learning the task adapted feature transformation and regularization to encode our preferences, domain prior knowledge and task oriented supervised information into the features. The proposed NACM is devoted to the classification task as a discriminative feature model and yield a novel discriminative nonlinear analysis operator learning framework (DNAOL). The theoretical analysis and experimental performances clearly demonstrate that DNAOL will not only achieve the better or at least competitive classification accuracies than the state-of-the-art algorithms but it can also dramatically reduce the time complexities in both training and testing phases.

  16. Machine Learning for Power System Disturbance and Cyber-attack Discrimination

    Energy Technology Data Exchange (ETDEWEB)

    Borges, Raymond Charles [ORNL; Beaver, Justin M [ORNL; Buckner, Mark A [ORNL; Morris, Thomas [Mississippi State University (MSU); Adhikari, Uttam [ORNL; Pan, Shengyi [Mississippi State University (MSU)

    2014-01-01

    Power system disturbances are inherently complex and can be attributed to a wide range of sources, including both natural and man-made events. Currently, the power system operators are heavily relied on to make decisions regarding the causes of experienced disturbances and the appropriate course of action as a response. In the case of cyber-attacks against a power system, human judgment is less certain since there is an overt attempt to disguise the attack and deceive the operators as to the true state of the system. To enable the human decision maker, we explore the viability of machine learning as a means for discriminating types of power system disturbances, and focus specifically on detecting cyber-attacks where deception is a core tenet of the event. We evaluate various machine learning methods as disturbance discriminators and discuss the practical implications for deploying machine learning systems as an enhancement to existing power system architectures.

  17. Aversive reinforcement improves visual discrimination learning in free-flying honeybees.

    Directory of Open Access Journals (Sweden)

    Aurore Avarguès-Weber

    Full Text Available BACKGROUND: Learning and perception of visual stimuli by free-flying honeybees has been shown to vary dramatically depending on the way insects are trained. Fine color discrimination is achieved when both a target and a distractor are present during training (differential conditioning, whilst if the same target is learnt in isolation (absolute conditioning, discrimination is coarse and limited to perceptually dissimilar alternatives. Another way to potentially enhance discrimination is to increase the penalty associated with the distractor. Here we studied whether coupling the distractor with a highly concentrated quinine solution improves color discrimination of both similar and dissimilar colors by free-flying honeybees. As we assumed that quinine acts as an aversive stimulus, we analyzed whether aversion, if any, is based on an aversive sensory input at the gustatory level or on a post-ingestional malaise following quinine feeding. METHODOLOGY/PRINCIPAL FINDINGS: We show that the presence of a highly concentrated quinine solution (60 mM acts as an aversive reinforcer promoting rejection of the target associated with it, and improving discrimination of perceptually similar stimuli but not of dissimilar stimuli. Free-flying bees did not use remote cues to detect the presence of quinine solution; the aversive effect exerted by this substance was mediated via a gustatory input, i.e. via a distasteful sensory experience, rather than via a post-ingestional malaise. CONCLUSION: The present study supports the hypothesis that aversion conditioning is important for understanding how and what animals perceive and learn. By using this form of conditioning coupled with appetitive conditioning in the framework of a differential conditioning procedure, it is possible to uncover discrimination capabilities that may remain otherwise unsuspected. We show, therefore, that visual discrimination is not an absolute phenomenon but can be modulated by experience.

  18. Noise-robust unsupervised spike sorting based on discriminative subspace learning with outlier handling

    Science.gov (United States)

    Keshtkaran, Mohammad Reza; Yang, Zhi

    2017-06-01

    Objective. Spike sorting is a fundamental preprocessing step for many neuroscience studies which rely on the analysis of spike trains. Most of the feature extraction and dimensionality reduction techniques that have been used for spike sorting give a projection subspace which is not necessarily the most discriminative one. Therefore, the clusters which appear inherently separable in some discriminative subspace may overlap if projected using conventional feature extraction approaches leading to a poor sorting accuracy especially when the noise level is high. In this paper, we propose a noise-robust and unsupervised spike sorting algorithm based on learning discriminative spike features for clustering. Approach. The proposed algorithm uses discriminative subspace learning to extract low dimensional and most discriminative features from the spike waveforms and perform clustering with automatic detection of the number of the clusters. The core part of the algorithm involves iterative subspace selection using linear discriminant analysis and clustering using Gaussian mixture model with outlier detection. A statistical test in the discriminative subspace is proposed to automatically detect the number of the clusters. Main results. Comparative results on publicly available simulated and real in vivo datasets demonstrate that our algorithm achieves substantially improved cluster distinction leading to higher sorting accuracy and more reliable detection of clusters which are highly overlapping and not detectable using conventional feature extraction techniques such as principal component analysis or wavelets. Significance. By providing more accurate information about the activity of more number of individual neurons with high robustness to neural noise and outliers, the proposed unsupervised spike sorting algorithm facilitates more detailed and accurate analysis of single- and multi-unit activities in neuroscience and brain machine interface studies.

  19. Aging effects on discrimination learning, logical reasoning and memory in pet dogs.

    Science.gov (United States)

    Wallis, Lisa J; Virányi, Zsófia; Müller, Corsin A; Serisier, Samuel; Huber, Ludwig; Range, Friederike

    2016-02-01

    In laboratory dogs, aging leads to a decline in various cognitive domains such as learning, memory and behavioural flexibility. However, much less is known about aging in pet dogs, i.e. dogs that are exposed to different home environments by their caregivers. We used tasks on a touchscreen apparatus to detect differences in various cognitive functions across pet Border Collies aged from 5 months to 13 years. Ninety-five dogs were divided into five age groups and tested in four tasks: (1) underwater photo versus drawing discrimination, (2) clip art picture discrimination, (3) inferential reasoning by exclusion and (4) a memory test with a retention interval of 6 months. The tasks were designed to test three cognitive abilities: visual discrimination learning, logical reasoning and memory. The total number of sessions to reach criterion and the number of correction trials needed in the two discrimination tasks were compared across age groups. The results showed that both measures increased linearly with age, with dogs aged over 13 years displaying slower learning and reduced flexibility in comparison to younger dogs. Inferential reasoning ability increased with age, but less than 10 % of dogs showed patterns of choice consistent with inference by exclusion. No age effect was found in the long-term memory test. In conclusion, the discrimination learning tests used are suitable to detect cognitive aging in pet dogs, which can serve as a basis for comparison to help diagnose cognition-related problems and as a tool to assist with the development of treatments to delay cognitive decline.

  20. Prefrontal Dynamics Underlying Rapid Instructed Task Learning Reverse with Practice

    Science.gov (United States)

    Cole, Michael W.; Bagic, Anto; Kass, Robert; Schneider, Walter

    2011-01-01

    The ability to rapidly reconfigure our minds to perform novel tasks is important for adapting to an ever-changing world, yet little is understood about its basis in the brain. Furthermore, it is unclear how this kind of task preparation changes with practice. Previous research suggests that prefrontal cortex (PFC) is essential when preparing to perform either novel or practiced tasks. Building upon recent evidence that PFC is organized in an anterior-to-posterior hierarchy, we postulated that novel and practiced task preparation would differentiate hierarchically distinct regions within PFC across time. Specifically, we hypothesized and confirmed using functional magnetic resonance imaging and magnetoencephalography with humans that novel task preparation is a bottom-up process that involves lower-level rule representations in dorsolateral PFC (DLPFC) before a higher-level rule-integrating task representation in anterior PFC (aPFC). In contrast, we identified a complete reversal of this activity pattern during practiced task preparation. Specifically, we found that practiced task preparation is a top-down process that involves a higher-level rule-integrating task representation (recalled from long-term memory) in aPFC before lower-level rule representations in DLPFC. These findings reveal two distinct yet highly inter-related mechanisms for task preparation, one involving task set formation from instructions during rapid instructed task learning and the other involving task set retrieval from long-term memory to facilitate familiar task performance. These two mechanisms demonstrate the exceptional flexibility of human PFC as it rapidly reconfigures cognitive brain networks to implement a wide variety of possible tasks. PMID:20962245

  1. Neonatal handling affects learning, reversal learning and antioxidant enzymes activities in a sex-specific manner in rats.

    Science.gov (United States)

    Noschang, Cristie; Krolow, Rachel; Arcego, Danusa Mar; Toniazzo, Ana Paula; Huffell, Ana Paula; Dalmaz, Carla

    2012-06-01

    Early life experiences have profound influences on behavior and neurochemical parameters in adult life. The aim of this study is to verify neonatal handling-induced sex specific differences on learning and reversal learning as well as oxidative stress parameters in the prefrontal cortex and striatum of adult rats. Litters of rats were non-handled or handled (10 min/day, days 1-10 after birth). In adulthood, learning and reversal learning were evaluated using a Y maze associated with palatable food in male and female rats. Morris water maze reversal learning was verified in males. Oxidative stress parameters were evaluated in both genders. Male neonatal handled animals had a worse performance in the Y maze reversal learning compared to non-handled ones and no difference was observed in the water maze reversal learning task. Regarding females, neonatal handled rats had a better performance during the Y maze learning phase compared to non-handled ones. In addition, neonatal handled female animals showed a decreased SOD/CAT ratio in the PFC compared to non-handled females. We conclude that neonatal handling effects on learning and memory in adult rats are sex and task specific. The sex specific differences are also observed in the evaluation of antioxidant enzymes activities with neonatal handling affecting only females. Copyright © 2012 ISDN. Published by Elsevier Ltd. All rights reserved.

  2. Enhancing the Biological Relevance of Machine Learning Classifiers for Reverse Vaccinology

    Directory of Open Access Journals (Sweden)

    Ashley I. Heinson

    2017-02-01

    Full Text Available Reverse vaccinology (RV is a bioinformatics approach that can predict antigens with protective potential from the protein coding genomes of bacterial pathogens for subunit vaccine design. RV has become firmly established following the development of the BEXSERO® vaccine against Neisseria meningitidis serogroup B. RV studies have begun to incorporate machine learning (ML techniques to distinguish bacterial protective antigens (BPAs from non-BPAs. This research contributes significantly to the RV field by using permutation analysis to demonstrate that a signal for protective antigens can be curated from published data. Furthermore, the effects of the following on an ML approach to RV were also assessed: nested cross-validation, balancing selection of non-BPAs for subcellular localization, increasing the training data, and incorporating greater numbers of protein annotation tools for feature generation. These enhancements yielded a support vector machine (SVM classifier that could discriminate BPAs (n = 200 from non-BPAs (n = 200 with an area under the curve (AUC of 0.787. In addition, hierarchical clustering of BPAs revealed that intracellular BPAs clustered separately from extracellular BPAs. However, no immediate benefit was derived when training SVM classifiers on data sets exclusively containing intra- or extracellular BPAs. In conclusion, this work demonstrates that ML classifiers have great utility in RV approaches and will lead to new subunit vaccines in the future.

  3. Enhancing the Biological Relevance of Machine Learning Classifiers for Reverse Vaccinology

    Science.gov (United States)

    Heinson, Ashley I.; Gunawardana, Yawwani; Moesker, Bastiaan; Denman Hume, Carmen C.; Vataga, Elena; Hall, Yper; Stylianou, Elena; McShane, Helen; Williams, Ann; Niranjan, Mahesan; Woelk, Christopher H.

    2017-01-01

    Reverse vaccinology (RV) is a bioinformatics approach that can predict antigens with protective potential from the protein coding genomes of bacterial pathogens for subunit vaccine design. RV has become firmly established following the development of the BEXSERO® vaccine against Neisseria meningitidis serogroup B. RV studies have begun to incorporate machine learning (ML) techniques to distinguish bacterial protective antigens (BPAs) from non-BPAs. This research contributes significantly to the RV field by using permutation analysis to demonstrate that a signal for protective antigens can be curated from published data. Furthermore, the effects of the following on an ML approach to RV were also assessed: nested cross-validation, balancing selection of non-BPAs for subcellular localization, increasing the training data, and incorporating greater numbers of protein annotation tools for feature generation. These enhancements yielded a support vector machine (SVM) classifier that could discriminate BPAs (n = 200) from non-BPAs (n = 200) with an area under the curve (AUC) of 0.787. In addition, hierarchical clustering of BPAs revealed that intracellular BPAs clustered separately from extracellular BPAs. However, no immediate benefit was derived when training SVM classifiers on data sets exclusively containing intra- or extracellular BPAs. In conclusion, this work demonstrates that ML classifiers have great utility in RV approaches and will lead to new subunit vaccines in the future. PMID:28157153

  4. Enhancing the Biological Relevance of Machine Learning Classifiers for Reverse Vaccinology.

    Science.gov (United States)

    Heinson, Ashley I; Gunawardana, Yawwani; Moesker, Bastiaan; Hume, Carmen C Denman; Vataga, Elena; Hall, Yper; Stylianou, Elena; McShane, Helen; Williams, Ann; Niranjan, Mahesan; Woelk, Christopher H

    2017-02-01

    Reverse vaccinology (RV) is a bioinformatics approach that can predict antigens with protective potential from the protein coding genomes of bacterial pathogens for subunit vaccine design. RV has become firmly established following the development of the BEXSERO® vaccine against Neisseria meningitidis serogroup B. RV studies have begun to incorporate machine learning (ML) techniques to distinguish bacterial protective antigens (BPAs) from non-BPAs. This research contributes significantly to the RV field by using permutation analysis to demonstrate that a signal for protective antigens can be curated from published data. Furthermore, the effects of the following on an ML approach to RV were also assessed: nested cross-validation, balancing selection of non-BPAs for subcellular localization, increasing the training data, and incorporating greater numbers of protein annotation tools for feature generation. These enhancements yielded a support vector machine (SVM) classifier that could discriminate BPAs (n = 200) from non-BPAs (n = 200) with an area under the curve (AUC) of 0.787. In addition, hierarchical clustering of BPAs revealed that intracellular BPAs clustered separately from extracellular BPAs. However, no immediate benefit was derived when training SVM classifiers on data sets exclusively containing intra- or extracellular BPAs. In conclusion, this work demonstrates that ML classifiers have great utility in RV approaches and will lead to new subunit vaccines in the future.

  5. Enhancing the Biological Relevance of Machine Learning Classifiers for Reverse Vaccinology

    KAUST Repository

    Heinson, Ashley

    2017-02-01

    Reverse vaccinology (RV) is a bioinformatics approach that can predict antigens with protective potential from the protein coding genomes of bacterial pathogens for subunit vaccine design. RV has become firmly established following the development of the BEXSERO® vaccine against Neisseria meningitidis serogroup B. RV studies have begun to incorporate machine learning (ML) techniques to distinguish bacterial protective antigens (BPAs) from non-BPAs. This research contributes significantly to the RV field by using permutation analysis to demonstrate that a signal for protective antigens can be curated from published data. Furthermore, the effects of the following on an ML approach to RV were also assessed: nested cross-validation, balancing selection of non-BPAs for subcellular localization, increasing the training data, and incorporating greater numbers of protein annotation tools for feature generation. These enhancements yielded a support vector machine (SVM) classifier that could discriminate BPAs (n = 200) from non-BPAs (n = 200) with an area under the curve (AUC) of 0.787. In addition, hierarchical clustering of BPAs revealed that intracellular BPAs clustered separately from extracellular BPAs. However, no immediate benefit was derived when training SVM classifiers on data sets exclusively containing intra- or extracellular BPAs. In conclusion, this work demonstrates that ML classifiers have great utility in RV approaches and will lead to new subunit vaccines in the future.

  6. Effects of toxaphene and endrin at very low dietary concentrations on discrimination acquisition and reversal in bobwhite quail, Colinus virginianus

    Science.gov (United States)

    Kreitzer, J.F.

    1980-01-01

    Adult male bobwhite quail Colinus virginianus were fed toxaphene (chlorinated camphene, 67?69% chlorine) at 10 and 50 ppm or endrin (1,2,3,4,10,10-hexachloro-6,7-epoxy-1,4,4a,5,6,7,8,8a-octahydro-1,4-endo-endo,5,8-dimethanonaphalene) at 0?1 and 1?0 ppm and their performance on non-spatial discrimination reversal tasks was measured. The birds were on dosage for 138 days (beginning at the age of 3 days) prior to testing. Two tests (with different pairs of patterns) were conducted with toxaphene-treated birds and five with endrin-treated birds. The toxaphene-treated birds made 50% more errors than did controls (p toxaphene in birds treated as adults appeared after about 30 days of treatment and those of endrin after about 40 days of treatment. Mean brain residues in endrin-treated birds were 0?075 ppm (wet weight basis) for the 0?1 ppm level birds and 0?35 ppm for the 1?0 ppm level birds.

  7. Male and female guppies differ in speed but not in accuracy in visual discrimination learning.

    Science.gov (United States)

    Lucon-Xiccato, Tyrone; Bisazza, Angelo

    2016-07-01

    In many species, males and females have different reproductive roles and/or differ in their ecological niche. Since in these cases the two sexes often face different cognitive challenges, selection may promote some degree of cognitive differentiation, an issue that has received relatively little attention so far. We investigated the existence of sex differences in visual discrimination learning in the guppy, Poecilia reticulata, a fish species in which females show complex mate choice based on male colour pattern. We tested males and females for their ability to learn a discrimination between two different shapes (experiment 1) and between two identical figures with a different orientation (experiment 2). In experiment 3, guppies were required to select an object of the odd colour in a group of five objects. Colours changed daily, and therefore, the solution for this task was facilitated by concept learning. We found males' and females' accuracy practically overlapped in the three experiments, suggesting that the two sexes have similar discrimination learning abilities. Yet, males showed faster decision time than females without any evident speed-accuracy trade-off. This result indicates the existence of consistent between-sex differences in decision speed perhaps due to impulsivity rather than speed in information processing. Our results align with previous literature, indicating that sex differences in cognitive abilities are the exception rather than the rule, while sex differences in cognitive style, i.e. the way in which an individual faces a cognitive task, are much more common.

  8. Maternal obesity caused by overnutrition exposure leads to reversal learning deficits and striatal disturbance in rats

    National Research Council Canada - National Science Library

    Wu, Ting; Deng, Shining; Li, Wei-Guang; Yu, Yongguo; Li, Fei; Mao, Meng

    2013-01-01

    .... Here, we report that pregnant obesity induced by exposure to excessive high fatty or highly palatable food specifically impaired reversal learning, a kind of adaptive behavior, while leaving serum...

  9. On the assimilation-discrimination relationship in American English adults' French vowel learning.

    Science.gov (United States)

    Levy, Erika S

    2009-11-01

    A quantitative "cross-language assimilation overlap" method for testing predictions of the Perceptual Assimilation Model (PAM) was implemented to compare results of a discrimination experiment with the listeners' previously reported assimilation data. The experiment examined discrimination of Parisian French (PF) front rounded vowels /y/ and /oe/. Three groups of American English listeners differing in their French experience (no experience [NoExp], formal experience [ModExp], and extensive formal-plus-immersion experience [HiExp]) performed discrimination of PF /y-u/, /y-o/, /oe-o/, /oe-u/, /y-i/, /y-epsilon/, /oe-epsilon/, /oe-i/, /y-oe/, /u-i/, and /a-epsilon/. Vowels were in bilabial /rabVp/ and alveolar /radVt/ contexts. More errors were found for PF front vs back rounded vowel pairs (16%) than for PF front unrounded vs rounded pairs (2%). Overall, ModExp listeners did not perform more accurately (11% errors) than NoExp listeners (13% errors). Extensive immersion experience, however, was associated with fewer errors (3%) than formal experience alone, although discrimination of PF /y-u/ remained relatively poor (12% errors) for HiExp listeners. More errors occurred on pairs involving front vs back rounded vowels in alveolar context (20% errors) than in bilabial (11% errors). Significant correlations were revealed between listeners' assimilation overlap scores and their discrimination errors, suggesting that the PAM may be extended to second-language (L2) vowel learning.

  10. Differential Brain Activity During Emotional vs. Non-emotional Reversal Learning

    OpenAIRE

    Nashiro, Kaoru; Sakaki, Michiko; Nga, Lin; Mather, Mara

    2012-01-01

    The ability to change an established stimulus-behavior association based on feedback is critical for adaptive social behaviors. This ability has been examined in reversal learning tasks, where participants first learn a stimulus-response association (e.g., select a particular object to get a reward), and then need to alter their response when reinforcement contingencies change. While substantial evidence demonstrates that the orbitofrontal cortex (OFC) is a critical region for reversal learni...

  11. Discriminative kernel feature extraction and learning for object recognition and detection

    DEFF Research Database (Denmark)

    Pan, Hong; Olsen, Søren Ingvor; Zhu, Yaping

    2015-01-01

    Feature extraction and learning is critical for object recognition and detection. By embedding context cue of image attributes into the kernel descriptors, we propose a set of novel kernel descriptors called context kernel descriptors (CKD). The motivation of CKD is to use the spatial consistency...... codebook and reduced CKD are discriminative. We report superior performance of our algorithm for object recognition on benchmark datasets like Caltech-101 and CIFAR-10, as well as for detection on a challenging chicken feet dataset....

  12. Mice Lacking M1 and M3 Muscarinic Acetylcholine Receptors Have Impaired Odor Discrimination and Learning

    Science.gov (United States)

    Chan, Wilson; Singh, Sanmeet; Keshav, Taj; Dewan, Ramita; Eberly, Christian; Maurer, Robert; Nunez-Parra, Alexia; Araneda, Ricardo C.

    2017-01-01

    The cholinergic system has extensive projections to the olfactory bulb (OB) where it produces a state-dependent regulation of sensory gating. Previous work has shown a prominent role of muscarinic acetylcholine (ACh) receptors (mAChRs) in regulating the excitability of OB neurons, in particular the M1 receptor. Here, we examined the contribution of M1 and M3 mAChR subtypes to olfactory processing using mice with a genetic deletion of these receptors, the M1−/− and the M1/M3−/− knockout (KO) mice. Genetic ablation of the M1 and M3 mAChRs resulted in a significant deficit in odor discrimination of closely related molecules, including stereoisomers. However, the discrimination of dissimilar molecules, social odors (e.g., urine) and novel object recognition was not affected. In addition the KO mice showed impaired learning in an associative odor-learning task, learning to discriminate odors at a slower rate, indicating that both short and long-term memory is disrupted by mAChR dysfunction. Interestingly, the KO mice exhibited decreased olfactory neurogenesis at younger ages, a deficit that was not maintained in older animals. In older animals, the olfactory deficit could be restored by increasing the number of new born neurons integrated into the OB after exposing them to an olfactory enriched environment, suggesting that muscarinic modulation and adult neurogenesis could be two different mechanism used by the olfactory system to improve olfactory processing. PMID:28210219

  13. Dissociable Hippocampal and Amygdalar D1-like receptor contribution to Discriminated Pavlovian conditioned approach learning

    Science.gov (United States)

    Andrzejewski, Matthew E; Ryals, Curtis

    2016-01-01

    Pavlovian conditioning is an elementary form of reward-related behavioral adaptation. The mesolimbic dopamine system is widely considered to mediate critical aspects of reward-related learning. For example, initial acquisition of positively-reinforced operant behavior requires dopamine (DA) D1 receptor (D1R) activation in the basolateral amygdala (BLA), central nucleus of the amygdala (CeA), and the ventral subiculum (vSUB). However, the role of D1R activation in these areas on appetitive, non-drug-related, Pavlovian learning is not currently known. In separate experiments, microinfusions of the D1-like receptor antagonist SCH-23390 (3.0 nmol/0.5 μL per side) into the amygdala and subiculum preceded discriminated Pavlovian conditioned approach (dPCA) training sessions. D1-like antagonism in all three structures impaired the acquisition of discriminated approach, but had no effect on performance after conditioning was asymptotic. Moreover, dissociable effects of D1-like antagonism in the three structures on components of discriminated responding were obtained. Lastly, the lack of latent inhibition in drug-treated groups may elucidate the role of D1-like in reward-related Pavlovian conditioning. The present data suggest a role for the D1 receptors in the amygdala and hippocampus in learning the significance of conditional stimuli, but not in the expression of conditional responses. PMID:26632336

  14. Dissociable hippocampal and amygdalar D1-like receptor contribution to discriminated Pavlovian conditioned approach learning.

    Science.gov (United States)

    Andrzejewski, Matthew E; Ryals, Curtis

    2016-02-15

    Pavlovian conditioning is an elementary form of reward-related behavioral adaptation. The mesolimbic dopamine system is widely considered to mediate critical aspects of reward-related learning. For example, initial acquisition of positively-reinforced operant behavior requires dopamine (DA) D1 receptor (D1R) activation in the basolateral amygdala (BLA), central nucleus of the amygdala (CeA), and the ventral subiculum (vSUB). However, the role of D1R activation in these areas on appetitive, non-drug-related, Pavlovian learning is not currently known. In separate experiments, microinfusions of the D1-like receptor antagonist SCH-23390 (3.0 nmol/0.5 μL per side) into the amygdala and subiculum preceded discriminated Pavlovian conditioned approach (dPCA) training sessions. D1-like antagonism in all three structures impaired the acquisition of discriminated approach, but had no effect on performance after conditioning was asymptotic. Moreover, dissociable effects of D1-like antagonism in the three structures on components of discriminated responding were obtained. Lastly, the lack of latent inhibition in drug-treated groups may elucidate the role of D1-like in reward-related Pavlovian conditioning. The present data suggest a role for the D1 receptors in the amygdala and hippocampus in learning the significance of conditional stimuli, but not in the expression of conditional responses.

  15. Learning discriminative distance functions for valve retrieval and improved decision support in valvular heart disease

    Science.gov (United States)

    Voigt, Ingmar; Vitanovski, Dime; Ionasec, Razvan I.; Tsymal, Alexey; Georgescu, Bogdan; Zhou, Shaohua K.; Huber, Martin; Navab, Nassir; Hornegger, Joachim; Comaniciu, Dorin

    2010-03-01

    Disorders of the heart valves constitute a considerable health problem and often require surgical intervention. Recently various approaches were published seeking to overcome the shortcomings of current clinical practice,that still relies on manually performed measurements for performance assessment. Clinical decisions are still based on generic information from clinical guidelines and publications and personal experience of clinicians. We present a framework for retrieval and decision support using learning based discriminative distance functions and visualization of patient similarity with relative neighborhood graphsbased on shape and derived features. We considered two learning based techniques, namely learning from equivalence constraints and the intrinsic Random Forest distance. The generic approach enables for learning arbitrary user-defined concepts of similarity depending on the application. This is demonstrated with the proposed applications, including automated diagnosis and interventional suitability classification, where classification rates of up to 88.9% and 85.9% could be observed on a set of valve models from 288 and 102 patients respectively.

  16. Pigeons Show Near-Optimal Win-Stay/Lose-Shift Performance on a Simultaneous-Discrimination, Midsession Reversal Task with Short Intertrial Intervals

    Science.gov (United States)

    Rayburn-Reeves, Rebecca M.; Laude, Jennifer R.; Zentall, Thomas R.

    2013-01-01

    Discrimination reversal tasks have been used as a measure of species flexibility in dealing with changes in reinforcement contingency. The simultaneous-discrimination, midsession reversal task is one in which one stimulus (S1) is correct for the first 40 trials of an 80-trial session and the other stimulus (S2) is correct for the remaining trials. After many sessions of training with this task, pigeons show a curious pattern of choices. They begin to respond to S2 well before the reversal point (they make anticipatory errors) and they continue to respond to S1 well after the reversal (they make perseverative errors). That is, they appear to be using the passage of time or number of trials into the session as a cue to reverse. We tested the hypothesis that these errors resulted in part from a memory deficit (the inability to remember over the intertrial interval, ITI, both the choice on the preceding trial and the outcome of that choice) by manipulating the duration of the ITI (1.5, 5, and 10 s). We found support for the hypothesis as pigeons with a short 1.5-s ITI showed close to optimal win-stay/lose-shift accuracy. PMID:23123672

  17. Perceptual learning and Aging: Improved performance for low contrast motion discrimination

    Directory of Open Access Journals (Sweden)

    Jeffrey eBower

    2013-02-01

    Full Text Available Previous research has shown age related differences in discriminating motion at different levels of contrast (Betts, Sekuler, & Bennett, 2009; 2012; Betts, Taylor, Sekuler & Bennett, 2005. A surprising result of this research is that older as compared to younger observers showed improved performance in detecting motion of large high contrast stimuli suggesting age-related differences in center-surround antagonism. In the present study we examined whether perceptual learning methods could be used to improve motion discrimination performance for older individuals under high- and low-contrast conditions. The stimuli were centrally presented Gaussian filtered sine-wave gratings (Gabors that were either 5 or 0.7 degree diameter with contrast of 0.92, 0.22, or 0.028. Older and younger participants received 3 days of training. The task was to identify if the motion direction was leftward or rightward. Duration thresholds for motion discrimination were derived using two randomly interleaved staircases and compared between pre-/post- test sessions. Both older and younger subjects showed lower duration thresholds as a result of training. The improved performance, for older subjects, due to training was observed for all size and contrast conditions, with training with small low-contrast stimuli resulting in a 23% improvement in motion discrimination performance. Older observers, as compared to younger observers, did show evidence of decreased spatial suppression across all contrast levels. These results suggest that perceptual learning techniques are effective for improving motion discrimination performance, especially for conditions that are difficult for older individuals.

  18. Neural substrate for higher-order learning in an insect: Mushroom bodies are necessary for configural discriminations.

    Science.gov (United States)

    Devaud, Jean-Marc; Papouin, Thomas; Carcaud, Julie; Sandoz, Jean-Christophe; Grünewald, Bernd; Giurfa, Martin

    2015-10-27

    Learning theories distinguish elemental from configural learning based on their different complexity. Although the former relies on simple and unambiguous links between the learned events, the latter deals with ambiguous discriminations in which conjunctive representations of events are learned as being different from their elements. In mammals, configural learning is mediated by brain areas that are either dispensable or partially involved in elemental learning. We studied whether the insect brain follows the same principles and addressed this question in the honey bee, the only insect in which configural learning has been demonstrated. We used a combination of conditioning protocols, disruption of neural activity, and optophysiological recording of olfactory circuits in the bee brain to determine whether mushroom bodies (MBs), brain structures that are essential for memory storage and retrieval, are equally necessary for configural and elemental olfactory learning. We show that bees with anesthetized MBs distinguish odors and learn elemental olfactory discriminations but not configural ones, such as positive and negative patterning. Inhibition of GABAergic signaling in the MB calyces, but not in the lobes, impairs patterning discrimination, thus suggesting a requirement of GABAergic feedback neurons from the lobes to the calyces for nonelemental learning. These results uncover a previously unidentified role for MBs besides memory storage and retrieval: namely, their implication in the acquisition of ambiguous discrimination problems. Thus, in insects as in mammals, specific brain regions are recruited when the ambiguity of learning tasks increases, a fact that reveals similarities in the neural processes underlying the elucidation of ambiguous tasks across species.

  19. Effects of stimulus salience on touchscreen serial reversal learning in a mouse model of fragile X syndrome.

    Science.gov (United States)

    Dickson, Price E; Corkill, Beau; McKimm, Eric; Miller, Mellessa M; Calton, Michele A; Goldowitz, Daniel; Blaha, Charles D; Mittleman, Guy

    2013-09-01

    Fragile X syndrome (FXS) is the most common inherited form of intellectual disability in males and the most common genetic cause of autism. Although executive dysfunction is consistently found in humans with FXS, evidence of executive dysfunction in Fmr1 KO mice, a mouse model of FXS, has been inconsistent. One possible explanation for this is that executive dysfunction in Fmr1 KO mice, similar to humans with FXS, is only evident when cognitive demands are high. Using touchscreen operant conditioning chambers, male Fmr1 KO mice and their male wildtype littermates were tested on the acquisition of a pairwise visual discrimination followed by four serial reversals of the response rule. We assessed reversal learning performance under two different conditions. In the first, the correct stimulus was salient and the incorrect stimulus was non-salient. In the second and more challenging condition, the incorrect stimulus was salient and the correct stimulus was non-salient; this increased cognitive load by introducing conflict between sensory-driven (i.e., bottom-up) and task-dependent (i.e., top-down) signals. Fmr1 KOs displayed two distinct impairments relative to wildtype littermates. First, Fmr1 KOs committed significantly more learning-type errors during the second reversal stage, but only under high cognitive load. Second, during the first reversal stage, Fmr1 KOs committed significantly more attempts to collect a reward during the timeout following an incorrect response. These findings indicate that Fmr1 KO mice display executive dysfunction that, in some cases, is only evident under high cognitive load.

  20. Spatial discrimination and visual discrimination

    DEFF Research Database (Denmark)

    Haagensen, Annika M. J.; Grand, Nanna; Klastrup, Signe

    2013-01-01

    Two methods investigating learning and memory in juvenile Gottingen minipigs were evaluated for potential use in preclinical toxicity testing. Twelve minipigs were tested using a spatial hole-board discrimination test including a learning phase and two memory phases. Five minipigs were tested...... in a visual discrimination test. The juvenile minipigs were able to learn the spatial hole-board discrimination test and showed improved working and reference memory during the learning phase. Performance in the memory phases was affected by the retention intervals, but the minipigs were able to remember...... the concept of the test in both memory phases. Working memory and reference memory were significantly improved in the last trials of the memory phases. In the visual discrimination test, the minipigs learned to discriminate between the three figures presented to them within 9-14 sessions. For the memory test...

  1. Dissociable effects of 5-HT2C receptor antagonism and genetic inactivation on perseverance and learned non-reward in an egocentric spatial reversal task.

    Directory of Open Access Journals (Sweden)

    Simon R O Nilsson

    Full Text Available Cognitive flexibility can be assessed in reversal learning tests, which are sensitive to modulation of 5-HT2C receptor (5-HT2CR function. Successful performance in these tests depends on at least two dissociable cognitive mechanisms which may separately dissipate associations of previous positive and negative valence. The first is opposed by perseverance and the second by learned non-reward. The current experiments explored the effect of reducing function of the 5-HT2CR on the cognitive mechanisms underlying egocentric reversal learning in the mouse. Experiment 1 used the 5-HT2CR antagonist SB242084 (0.5 mg/kg in a between-groups serial design and Experiment 2 used 5-HT2CR KO mice in a repeated measures design. Animals initially learned to discriminate between two egocentric turning directions, only one of which was food rewarded (denoted CS+, CS-, in a T- or Y-maze configuration. This was followed by three conditions; (1 Full reversal, where contingencies reversed; (2 Perseverance, where the previous CS+ became CS- and the previous CS- was replaced by a novel CS+; (3 Learned non-reward, where the previous CS- became CS+ and the previous CS+ was replaced by a novel CS-. SB242084 reduced perseverance, observed as a decrease in trials and incorrect responses to criterion, but increased learned non-reward, observed as an increase in trials to criterion. In contrast, 5-HT2CR KO mice showed increased perseverance. 5-HT2CR KO mice also showed retarded egocentric discrimination learning. Neither manipulation of 5-HT2CR function affected performance in the full reversal test. These results are unlikely to be accounted for by increased novelty attraction, as SB242084 failed to affect performance in an unrewarded novelty task. In conclusion, acute 5-HT2CR antagonism and constitutive loss of the 5-HT2CR have opposing effects on perseverance in egocentric reversal learning in mice. It is likely that this difference reflects the broader impact of 5HT2CR loss

  2. Dynamic Changes in Acetylcholine Output in the Medial Striatum during Place Reversal Learning

    Science.gov (United States)

    Ragozzino, Michael E.; Choi, Daniel

    2004-01-01

    The present studies explored the role of the medial striatum in learning when task contingencies change. Experiment 1 examined whether the medial striatum is involved in place reversal learning. Testing occurred in a modified cross-maze across two consecutive sessions. Injections of the local anesthetic, bupivacaine, into the medial striatum, did…

  3. Deletion of glycine transporter 1 (GlyT1) in forebrain neurons facilitates reversal learning: enhanced cognitive adaptability?

    Science.gov (United States)

    Singer, Philipp; Boison, Detlev; Möhler, Hanns; Feldon, Joram; Yee, Benjamin K

    2009-10-01

    Local availability of glycine near N-methyl-D-aspartate receptors (NMDARs) is partly regulated by neuronal glycine transporter 1 (GlyT1), which can therefore modulate NMDAR function because binding to the glycine site of the NMDAR is necessary for channel activation. Disrupting GlyT1 in forebrain neurons has been shown to enhance Pavlovian conditioning and object recognition memory. Here, the authors report that the same genetic manipulation facilitated reversal learning in the water maze test of reference memory, but did not lead to any clear improvement in a working memory version of the water maze test. Facilitation in a nonspatial discrimination reversal task conducted on a T maze was also observed, supporting the conclusion that forebrain neuronal GlyT1 may modulate the flexibility in (new) learning and relevant mnemonic functions. One possibility is that these phenotypes may reflect reduced susceptibility to certain forms of proactive interference. This may be relevant for the suggested clinical application of GlyT1 inhibitors in the treatment of cognitive deficits, including schizophrenia, which is characterized by cognitive inflexibility in addition to the positive symptoms of the disease.

  4. Normative data and discriminant validity of Rey's Verbal Learning Test for the Greek adult population.

    Science.gov (United States)

    Messinis, Lambros; Tsakona, Ioanna; Malefaki, Sonia; Papathanasopoulos, Panagiotis

    2007-08-01

    The present study sought to establish normative and discriminant validity data for Rey's Auditory Verbal Learning Test [Rey, A. (1964). L 'examen clinique en psychologie [Clinical tests in psychology]. Paris: Presses Universitaires de France; Schmidt, M. (1996). Rey auditory verbal learning test: A handbook. Los Angeles, CA: Western Psychological Services] using newly adapted learning lists for the Greek adult population. Applying the procedure suggested by Geffen et al. [Geffen, G., Moar, K. J., O'Hanlon, A. P., Clark, C. R., & Geffen, L. N. (1990). Performance measures of 16-86-year-old males and females on the auditory verbal learning test. The Clinical Neuropsychologist, 4, 45-63] we administered the test to 205 healthy participants, aged 18-78 years and two adult patient groups (long-term cannabis users and HIV symptomatic patients). Stepwise linear regression analyses showed that the variables age, education and gender contributed significantly to most trials of the RAVLT. Performance decreased in an age-dependent manner from young adulthood. Women, young adults and higher educated participants outperformed men, older adults and less educated individuals. The test appears to discriminate adequately between the performance of long-term heavy cannabis users and HIV seropositive symptomatic patients and matched healthy controls, as both patient groups performed more poorly than their respective control group. Normative data stratified by age, gender and education for the Greek adult population is presented for use in research and clinical settings.

  5. Does Fine Color Discrimination Learning in Free-Flying Honeybees Change Mushroom-Body Calyx Neuroarchitecture?

    Science.gov (United States)

    Sommerlandt, Frank M J; Spaethe, Johannes; Rössler, Wolfgang; Dyer, Adrian G

    2016-01-01

    Honeybees learn color information of rewarding flowers and recall these memories in future decisions. For fine color discrimination, bees require differential conditioning with a concurrent presentation of target and distractor stimuli to form a long-term memory. Here we investigated whether the long-term storage of color information shapes the neural network of microglomeruli in the mushroom body calyces and if this depends on the type of conditioning. Free-flying honeybees were individually trained to a pair of perceptually similar colors in either absolute conditioning towards one of the colors or in differential conditioning with both colors. Subsequently, bees of either conditioning groups were tested in non-rewarded discrimination tests with the two colors. Only bees trained with differential conditioning preferred the previously learned color, whereas bees of the absolute conditioning group, and a stimuli-naïve group, chose randomly among color stimuli. All bees were then kept individually for three days in the dark to allow for complete long-term memory formation. Whole-mount immunostaining was subsequently used to quantify variation of microglomeruli number and density in the mushroom-body lip and collar. We found no significant differences among groups in neuropil volumes and total microglomeruli numbers, but learning performance was negatively correlated with microglomeruli density in the absolute conditioning group. Based on these findings we aim to promote future research approaches combining behaviorally relevant color learning tests in honeybees under free-flight conditions with neuroimaging analysis; we also discuss possible limitations of this approach.

  6. Depth-Aware Salient Object Detection and Segmentation via Multiscale Discriminative Saliency Fusion and Bootstrap Learning.

    Science.gov (United States)

    Song, Hangke; Liu, Zhi; Du, Huan; Sun, Guangling; Le Meur, Olivier; Ren, Tongwei

    2017-09-01

    This paper proposes a novel depth-aware salient object detection and segmentation framework via multiscale discriminative saliency fusion (MDSF) and bootstrap learning for RGBD images (RGB color images with corresponding Depth maps) and stereoscopic images. By exploiting low-level feature contrasts, mid-level feature weighted factors and high-level location priors, various saliency measures on four classes of features are calculated based on multiscale region segmentation. A random forest regressor is learned to perform the discriminative saliency fusion (DSF) and generate the DSF saliency map at each scale, and DSF saliency maps across multiple scales are combined to produce the MDSF saliency map. Furthermore, we propose an effective bootstrap learning-based salient object segmentation method, which is bootstrapped with samples based on the MDSF saliency map and learns multiple kernel support vector machines. Experimental results on two large datasets show how various categories of features contribute to the saliency detection performance and demonstrate that the proposed framework achieves the better performance on both saliency detection and salient object segmentation.

  7. Discriminative Dictionary Learning With Two-Level Low Rank and Group Sparse Decomposition for Image Classification.

    Science.gov (United States)

    Wen, Zaidao; Hou, Biao; Jiao, Licheng

    2016-06-30

    Discriminative dictionary learning (DDL) framework has been widely used in image classification which aims to learn some class-specific feature vectors as well as a representative dictionary according to a set of labeled training samples. However, interclass similarities and intraclass variances among input samples and learned features will generally weaken the representability of dictionary and the discrimination of feature vectors so as to degrade the classification performance. Therefore, how to explicitly represent them becomes an important issue. In this paper, we present a novel DDL framework with two-level low rank and group sparse decomposition model. In the first level, we learn a class-shared and several class-specific dictionaries, where a low rank and a group sparse regularization are, respectively, imposed on the corresponding feature matrices. In the second level, the class-specific feature matrix will be further decomposed into a low rank and a sparse matrix so that intraclass variances can be separated to concentrate the corresponding feature vectors. Extensive experimental results demonstrate the effectiveness of our model. Compared with the other state-of-the-arts on several popular image databases, our model can achieve a competitive or better performance in terms of the classification accuracy.

  8. Vortioxetine restores reversal learning impaired by 5-HT depletion or chronic intermittent cold stress in rats.

    Science.gov (United States)

    Wallace, Ashley; Pehrson, Alan L; Sánchez, Connie; Morilak, David A

    2014-10-01

    Current treatments for depression, including serotonin-specific reuptake inhibitors (SSRIs), are only partially effective, with a high incidence of residual symptoms, relapse, and treatment resistance. Loss of cognitive flexibility, a component of depression, is associated with dysregulation of the prefrontal cortex. Reversal learning, a form of cognitive flexibility, is impaired by chronic stress, a risk factor for depression, and the stress-induced impairment in reversal learning is sensitive to chronic SSRI treatment, and is mimicked by serotonin (5-HT) depletion. Vortioxetine, a novel, multimodal-acting antidepressant, is a 5-HT3, 5-HT7 and 5-HT1D receptor antagonist, a 5-HT1B receptor partial agonist, a 5-HT1A receptor agonist, and inhibits the 5-HT transporter. Using adult male rats, we first investigated the direct effects of vortioxetine, acting at post-synaptic 5-HT receptors, on reversal learning that was compromised by 5-HT depletion using 4-chloro-DL-phenylalanine methyl ester hydrochloride (PCPA), effectively eliminating any contribution of 5-HT reuptake blockade. PCPA induced a reversal learning impairment that was alleviated by acute or sub-chronic vortioxetine administration, suggesting that post-synaptic 5-HT receptor activation contributes to the effects of vortioxetine. We then investigated the effects of chronic dietary administration of vortioxetine on reversal learning that had been compromised in intact animals exposed to chronic intermittent cold (CIC) stress, to assess vortioxetine's total pharmacological effect. CIC stress impaired reversal learning, and chronic vortioxetine administration prevented the reversal-learning deficit. Together, these results suggest that the direct effect of vortioxetine at 5-HT receptors may contribute to positive effects on cognitive flexibility deficits, and may enhance the effect of 5-HT reuptake blockade.

  9. A discriminative learning framework with pairwise constraints for video object classification.

    Science.gov (United States)

    Yan, Rong; Zhang, Jian; Yang, Jie; Hauptmann, Alexander G

    2006-04-01

    To deal with the problem of insufficient labeled data in video object classification, one solution is to utilize additional pairwise constraints that indicate the relationship between two examples, i.e., whether these examples belong to the same class or not. In this paper, we propose a discriminative learning approach which can incorporate pairwise constraints into a conventional margin-based learning framework. Different from previous work that usually attempts to learn better distance metrics or estimate the underlying data distribution, the proposed approach can directly model the decision boundary and, thus, require fewer model assumptions. Moreover, the proposed approach can handle both labeled data and pairwise constraints in a unified framework. In this work, we investigate two families of pairwise loss functions, namely, convex and nonconvex pairwise loss functions, and then derive three pairwise learning algorithms by plugging in the hinge loss and the logistic loss functions. The proposed learning algorithms were evaluated using a people identification task on two surveillance video data sets. The experiments demonstrated that the proposed pairwise learning algorithms considerably outperform the baseline classifiers using only labeled data and two other pairwise learning algorithms with the same amount of pairwise constraints.

  10. English- and Mandarin-learning infants' discrimination of actions and objects in dynamic events.

    Science.gov (United States)

    Chen, Jie; Tardif, Twila; Pulverman, Rachel; Casasola, Marianella; Zhu, Liqi; Zheng, Xiaobei; Meng, Xiangzhi

    2015-10-01

    The present studies examined the role of linguistic experience in directing English and Mandarin learners' attention to aspects of a visual scene. Specifically, they asked whether young language learners in these 2 cultures attend to differential aspects of a word-learning situation. Two groups of English and Mandarin learners, 6-8-month-olds (n = 65) and 17-19-month-olds (n = 91), participated in 2 studies, based on a habituation paradigm, designed to test infants' discrimination between actions and objects in dynamic events. In Study 1, these stimuli were presented in silence, whereas in Study 2, a verbal label accompanied videos. Results showed that 6-8-month-olds could discriminate action changes but not object changes, whereas 17-19-month-olds could discriminate both types of changes. However, there were only very subtle cross-linguistic differences in these patterns when the scenes were presented together with a verbal label. These findings show strong evidence for universal developmental trends in attention, with somewhat weaker evidence that the differences in the types of words Mandarin- versus English-learning children produce or are exposed to affect attention to different aspects of a scene in the first 2 years of life. (c) 2015 APA, all rights reserved).

  11. Machinery fault diagnosis using joint global and local/nonlocal discriminant analysis with selective ensemble learning

    Science.gov (United States)

    Yu, Jianbo

    2016-11-01

    The vibration signals of faulty machine are generally non-stationary and nonlinear under those complicated working conditions. Thus, it is a big challenge to extract and select the effective features from vibration signals for machinery fault diagnosis. This paper proposes a new manifold learning algorithm, joint global and local/nonlocal discriminant analysis (GLNDA), which aims to extract effective intrinsic geometrical information from the given vibration data. Comparisons with other regular methods, principal component analysis (PCA), local preserving projection (LPP), linear discriminant analysis (LDA) and local LDA (LLDA), illustrate the superiority of GLNDA in machinery fault diagnosis. Based on the extracted information by GLNDA, a GLNDA-based Fisher discriminant rule (FDR) is put forward and applied to machinery fault diagnosis without additional recognizer construction procedure. By importing Bagging into GLNDA score-based feature selection and FDR, a novel manifold ensemble method (selective GLNDA ensemble, SE-GLNDA) is investigated for machinery fault diagnosis. The motivation for developing ensemble of manifold learning components is that it can achieve higher accuracy and applicability than single component in machinery fault diagnosis. The effectiveness of the SE-GLNDA-based fault diagnosis method has been verified by experimental results from bearing full life testers.

  12. Recognition vs Reverse Engineering in Boolean Concepts Learning

    Science.gov (United States)

    Shafat, Gabriel; Levin, Ilya

    2012-01-01

    This paper deals with two types of logical problems--recognition problems and reverse engineering problems, and with the interrelations between these types of problems. The recognition problems are modeled in the form of a visual representation of various objects in a common pattern, with a composition of represented objects in the pattern.…

  13. Faster native vowel discrimination learning in musicians is mediated by an optimization of mnemonic functions.

    Science.gov (United States)

    Elmer, Stefan; Greber, Marielle; Pushparaj, Arethy; Kühnis, Jürg; Jäncke, Lutz

    2017-09-01

    The ability to discriminate phonemes varying in spectral and temporal attributes constitutes one of the most basic intrinsic elements underlying language learning mechanisms. Since previous work has consistently shown that professional musicians are characterized by perceptual and cognitive advantages in a variety of language-related tasks, and since vowels can be considered musical sounds within the domain of speech, here we investigated the behavioral and electrophysiological correlates of native vowel discrimination learning in a sample of professional musicians and non-musicians. We evaluated the contribution of both the neurophysiological underpinnings of perceptual (i.e., N1/P2 complex) and mnemonic functions (i.e., N400 and P600 responses) while the participants were instructed to judge whether pairs of native consonant-vowel (CV) syllables manipulated in the first formant transition of the vowel (i.e., from /tu/ to /to/) were identical or not. Results clearly demonstrated faster learning in musicians, compared to non-musicians, as reflected by shorter reaction times and higher accuracy. Most notably, in terms of morphology, time course, and voltage strength, this steeper learning curve was accompanied by distinctive N400 and P600 manifestations between the two groups. In contrast, we did not reveal any group differences during the early stages of auditory processing (i.e., N1/P2 complex), suggesting that faster learning was mediated by an optimization of mnemonic but not perceptual functions. Based on a clear taxonomy of the mnemonic functions involved in the task, results are interpreted as pointing to a relationship between faster learning mechanisms in musicians and an optimization of echoic (i.e., N400 component) and working memory (i.e., P600 component) functions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Sparse representation for infrared Dim target detection via a discriminative over-complete dictionary learned online.

    Science.gov (United States)

    Li, Zheng-Zhou; Chen, Jing; Hou, Qian; Fu, Hong-Xia; Dai, Zhen; Jin, Gang; Li, Ru-Zhang; Liu, Chang-Ju

    2014-05-27

    It is difficult for structural over-complete dictionaries such as the Gabor function and discriminative over-complete dictionary, which are learned offline and classified manually, to represent natural images with the goal of ideal sparseness and to enhance the difference between background clutter and target signals. This paper proposes an infrared dim target detection approach based on sparse representation on a discriminative over-complete dictionary. An adaptive morphological over-complete dictionary is trained and constructed online according to the content of infrared image by K-singular value decomposition (K-SVD) algorithm. Then the adaptive morphological over-complete dictionary is divided automatically into a target over-complete dictionary describing target signals, and a background over-complete dictionary embedding background by the criteria that the atoms in the target over-complete dictionary could be decomposed more sparsely based on a Gaussian over-complete dictionary than the one in the background over-complete dictionary. This discriminative over-complete dictionary can not only capture significant features of background clutter and dim targets better than a structural over-complete dictionary, but also strengthens the sparse feature difference between background and target more efficiently than a discriminative over-complete dictionary learned offline and classified manually. The target and background clutter can be sparsely decomposed over their corresponding over-complete dictionaries, yet couldn't be sparsely decomposed based on their opposite over-complete dictionary, so their residuals after reconstruction by the prescribed number of target and background atoms differ very visibly. Some experiments are included and the results show that this proposed approach could not only improve the sparsity more efficiently, but also enhance the performance of small target detection more effectively.

  15. On the assimilation-discrimination relationship in American English adults’ French vowel learning1

    Science.gov (United States)

    Levy, Erika S.

    2009-01-01

    A quantitative “cross-language assimilation overlap” method for testing predictions of the Perceptual Assimilation Model (PAM) was implemented to compare results of a discrimination experiment with the listeners’ previously reported assimilation data. The experiment examined discrimination of Parisian French (PF) front rounded vowels ∕y∕ and ∕œ∕. Three groups of American English listeners differing in their French experience (no experience [NoExp], formal experience [ModExp], and extensive formal-plus-immersion experience [HiExp]) performed discrimination of PF ∕y-u∕, ∕y-o∕, ∕œ-o∕, ∕œ-u∕, ∕y-i∕, ∕y-ɛ∕, ∕œ-ɛ∕, ∕œ-i∕, ∕y-œ∕, ∕u-i∕, and ∕a-ɛ∕. Vowels were in bilabial ∕rabVp∕ and alveolar ∕radVt∕ contexts. More errors were found for PF front vs back rounded vowel pairs (16%) than for PF front unrounded vs rounded pairs (2%). Overall, ModExp listeners did not perform more accurately (11% errors) than NoExp listeners (13% errors). Extensive immersion experience, however, was associated with fewer errors (3%) than formal experience alone, although discrimination of PF ∕y-u∕ remained relatively poor (12% errors) for HiExp listeners. More errors occurred on pairs involving front vs back rounded vowels in alveolar context (20% errors) than in bilabial (11% errors). Significant correlations were revealed between listeners’ assimilation overlap scores and their discrimination errors, suggesting that the PAM may be extended to second-language (L2) vowel learning. PMID:19894844

  16. Improved Discriminability of Spatiotemporal Neural Patterns in Rat Motor Cortical Areas as Directional Choice Learning Progresses

    Directory of Open Access Journals (Sweden)

    Hongwei eMao

    2015-03-01

    Full Text Available Animals learn to choose a proper action among alternatives to improve their odds of success in food foraging and other activities critical for survival. Through trial-and-error, they learn correct associations between their choices and external stimuli. While a neural network that underlies such learning process has been identified at a high level, it is still unclear how individual neurons and a neural ensemble adapt as learning progresses. In this study, we monitored the activity of single units in the rat medial and lateral agranular (AGm and AGl, respectively areas as rats learned to make a left or right side lever press in response to a left or right side light cue. We noticed that rat movement parameters during the performance of the directional choice task quickly became stereotyped during the first 2-3 days or sessions. But learning the directional choice problem took weeks to occur. Accompanying rats’ behavioral performance adaptation, we observed neural modulation by directional choice in recorded single units. Our analysis shows that ensemble mean firing rates in the cue-on period did not change significantly as learning progressed, and the ensemble mean rate difference between left and right side choices did not show a clear trend of change either. However, the spatiotemporal firing patterns of the neural ensemble exhibited improved discriminability between the two directional choices through learning. These results suggest a spatiotemporal neural coding scheme in a motor cortical neural ensemble that may be responsible for and contributing to learning the directional choice task.

  17. From bird to sparrow: Learning-induced modulations in fine-grained semantic discrimination.

    Science.gov (United States)

    De Meo, Rosanna; Bourquin, Nathalie M-P; Knebel, Jean-François; Murray, Micah M; Clarke, Stephanie

    2015-09-01

    Recognition of environmental sounds is believed to proceed through discrimination steps from broad to more narrow categories. Very little is known about the neural processes that underlie fine-grained discrimination within narrow categories or about their plasticity in relation to newly acquired expertise. We investigated how the cortical representation of birdsongs is modulated by brief training to recognize individual species. During a 60-minute session, participants learned to recognize a set of birdsongs; they improved significantly their performance for trained (T) but not control species (C), which were counterbalanced across participants. Auditory evoked potentials (AEPs) were recorded during pre- and post-training sessions. Pre vs. post changes in AEPs were significantly different between T and C i) at 206-232ms post stimulus onset within a cluster on the anterior part of the left superior temporal gyrus; ii) at 246-291ms in the left middle frontal gyrus; and iii) 512-545ms in the left middle temporal gyrus as well as bilaterally in the cingulate cortex. All effects were driven by weaker activity for T than C species. Thus, expertise in discriminating T species modulated early stages of semantic processing, during and immediately after the time window that sustains the discrimination between human vs. animal vocalizations. Moreover, the training-induced plasticity is reflected by the sharpening of a left lateralized semantic network, including the anterior part of the temporal convexity and the frontal cortex. Training to identify birdsongs influenced, however, also the processing of C species, but at a much later stage. Correct discrimination of untrained sounds seems to require an additional step which results from lower-level features analysis such as apperception. We therefore suggest that the access to objects within an auditory semantic category is different and depends on subject's level of expertise. More specifically, correct intra

  18. Deformable segmentation of 3D MR prostate images via distributed discriminative dictionary and ensemble learning

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yanrong; Shao, Yeqin [Department of Radiology and BRIC, University of North Carolina at Chapel Hill, North Carolina 27599 (United States); Gao, Yaozong; Price, True [Department of Radiology and BRIC, University of North Carolina at Chapel Hill, North Carolina 27599 and Department of Computer Science, University of North Carolina at Chapel Hill, North Carolina 27599 (United States); Oto, Aytekin [Department of Radiology, Section of Urology, University of Chicago, Illinois 60637 (United States); Shen, Dinggang, E-mail: dgshen@med.unc.edu [Department of Radiology and BRIC, University of North Carolina at Chapel Hill, North Carolina 27599 and Department of Brain and Cognitive Engineering, Korea University, Seoul 136-713 (Korea, Republic of)

    2014-07-15

    Purpose: Automatic prostate segmentation from MR images is an important task in various clinical applications such as prostate cancer staging and MR-guided radiotherapy planning. However, the large appearance and shape variations of the prostate in MR images make the segmentation problem difficult to solve. Traditional Active Shape/Appearance Model (ASM/AAM) has limited accuracy on this problem, since its basic assumption, i.e., both shape and appearance of the targeted organ follow Gaussian distributions, is invalid in prostate MR images. To this end, the authors propose a sparse dictionary learning method to model the image appearance in a nonparametric fashion and further integrate the appearance model into a deformable segmentation framework for prostate MR segmentation. Methods: To drive the deformable model for prostate segmentation, the authors propose nonparametric appearance and shape models. The nonparametric appearance model is based on a novel dictionary learning method, namely distributed discriminative dictionary (DDD) learning, which is able to capture fine distinctions in image appearance. To increase the differential power of traditional dictionary-based classification methods, the authors' DDD learning approach takes three strategies. First, two dictionaries for prostate and nonprostate tissues are built, respectively, using the discriminative features obtained from minimum redundancy maximum relevance feature selection. Second, linear discriminant analysis is employed as a linear classifier to boost the optimal separation between prostate and nonprostate tissues, based on the representation residuals from sparse representation. Third, to enhance the robustness of the authors' classification method, multiple local dictionaries are learned for local regions along the prostate boundary (each with small appearance variations), instead of learning one global classifier for the entire prostate. These discriminative dictionaries are located on

  19. Mirror reversal and visual rotation are learned and consolidated via separate mechanisms: recalibrating or learning de novo?

    Science.gov (United States)

    Telgen, Sebastian; Parvin, Darius; Diedrichsen, Jörn

    2014-10-01

    Motor learning tasks are often classified into adaptation tasks, which involve the recalibration of an existing control policy (the mapping that determines both feedforward and feedback commands), and skill-learning tasks, requiring the acquisition of new control policies. We show here that this distinction also applies to two different visuomotor transformations during reaching in humans: Mirror-reversal (left-right reversal over a mid-sagittal axis) of visual feedback versus rotation of visual feedback around the movement origin. During mirror-reversal learning, correct movement initiation (feedforward commands) and online corrections (feedback responses) were only generated at longer latencies. The earliest responses were directed into a nonmirrored direction, even after two training sessions. In contrast, for visual rotation learning, no dependency of directional error on reaction time emerged, and fast feedback responses to visual displacements of the cursor were immediately adapted. These results suggest that the motor system acquires a new control policy for mirror reversal, which initially requires extra processing time, while it recalibrates an existing control policy for visual rotations, exploiting established fast computational processes. Importantly, memory for visual rotation decayed between sessions, whereas memory for mirror reversals showed offline gains, leading to better performance at the beginning of the second session than in the end of the first. With shifts in time-accuracy tradeoff and offline gains, mirror-reversal learning shares common features with other skill-learning tasks. We suggest that different neuronal mechanisms underlie the recalibration of an existing versus acquisition of a new control policy and that offline gains between sessions are a characteristic of latter.

  20. Asymmetry of attentional set in rhesus monkeys learning colour and shape discriminations

    OpenAIRE

    Baxter, Mark G.; Gaffan, David

    2006-01-01

    We trained rhesus monkeys on six visual discrimination problems using stimuli that varied in both shape and colour. For one group of animals shape was always relevant in these six problems, and colour always irrelevant, and for the other animals vice versa. During these “intradimensional shifts” (ID) the problems were learned at equal rates by the two groups, shape-relevant and colour-relevant. We then trained three further problems in which the other dimension was now relevant (“extradimensi...

  1. Nonverbal Disorders of Learning: The Reverse of Dyslexia?

    Science.gov (United States)

    Badian, Nathlie A.

    1986-01-01

    Teacher perceptions of the social-behavioral characteristics of 99 boys (aged 7-14) identified by their nonverbal learning abilities found that low nonverbal subjects showed good left-brain functioning, good reading, poor right-brain functioning, poor arithmetic skills, low motivation, poor work habits, disorganization, and poor relationship with…

  2. Beyond reversal: a critical role for human orbitofrontal cortex in flexible learning from probabilistic feedback.

    Science.gov (United States)

    Tsuchida, Ami; Doll, Bradley B; Fellows, Lesley K

    2010-12-15

    Damage to the orbitofrontal cortex (OFC) has been linked to impaired reinforcement processing and maladaptive behavior in changing environments across species. Flexible stimulus-outcome learning, canonically captured by reversal learning tasks, has been shown to rely critically on OFC in rats, monkeys, and humans. However, the precise role of OFC in this learning remains unclear. Furthermore, whether other frontal regions also contribute has not been definitively established, particularly in humans. In the present study, a reversal learning task with probabilistic feedback was administered to 39 patients with focal lesions affecting various sectors of the frontal lobes and to 51 healthy, demographically matched control subjects. Standard groupwise comparisons were supplemented with voxel-based lesion-symptom mapping to identify regions within the frontal lobes critical for task performance. Learning in this dynamic stimulus-reinforcement environment was considered both in terms of overall performance and at the trial-by-trial level. In this challenging, probabilistic context, OFC damage disrupted both initial and reversal learning. Trial-by-trial performance patterns suggest that OFC plays a critical role in interpreting feedback from a particular trial within the broader context of the outcome history across trials rather than in simply suppressing preexisting stimulus-outcome associations. The findings show that OFC, and not other prefrontal regions, plays a necessary role in flexible stimulus-reinforcement learning in humans.

  3. The temporal dynamics of reversal learning: P3 amplitude predicts valence-specific behavioral adjustment.

    Science.gov (United States)

    Donaldson, Kayla R; Ait Oumeziane, Belel; Hélie, Sebastien; Foti, Dan

    2016-07-01

    Adapting behavior to dynamic stimulus-reward contingences is a core feature of reversal learning and a capacity thought to be critical to socio-emotional behavior. Impairment in reversal learning has been linked to multiple psychiatric outcomes, including depression, Parkinson's disorder, and substance abuse. A recent influential study introduced an innovative laboratory reversal-learning paradigm capable of disentangling the roles of feedback valence and expectancy. Here, we sought to use this paradigm in order to examine the time-course of reward and punishment learning using event-related potentials among a large, representative sample (N=101). Three distinct phases of processing were examined: initial feedback evaluation (reward positivity, or RewP), allocation of attention (P3), and sustained processing (late positive potential, or LPP). Results indicate a differential pattern of valence and expectancy across these processing stages: the RewP was uniquely related to valence (i.e., positive vs. negative feedback), the P3 was uniquely associated with expectancy (i.e., unexpected vs. expected feedback), and the LPP was sensitive to both valence and expectancy (i.e., main effects of each, but no interaction). The link between ERP amplitudes and behavioral performance was strongest for the P3, and this association was valence-specific. Overall, these findings highlight the potential utility of the P3 as a neural marker for feedback processing in reversal-based learning and establish a foundation for future research in clinical populations.

  4. Accurate classification of brain gliomas by discriminate dictionary learning based on projective dictionary pair learning of proton magnetic resonance spectra.

    Science.gov (United States)

    Adebileje, Sikiru Afolabi; Ghasemi, Keyvan; Aiyelabegan, Hammed Tanimowo; Saligheh Rad, Hamidreza

    2017-04-01

    Proton magnetic resonance spectroscopy is a powerful noninvasive technique that complements the structural images of cMRI, which aids biomedical and clinical researches, by identifying and visualizing the compositions of various metabolites within the tissues of interest. However, accurate classification of proton magnetic resonance spectroscopy is still a challenging issue in clinics due to low signal-to-noise ratio, overlapping peaks of metabolites, and the presence of background macromolecules. This paper evaluates the performance of a discriminate dictionary learning classifiers based on projective dictionary pair learning method for brain gliomas proton magnetic resonance spectroscopy spectra classification task, and the result were compared with the sub-dictionary learning methods. The proton magnetic resonance spectroscopy data contain a total of 150 spectra (74 healthy, 23 grade II, 23 grade III, and 30 grade IV) from two databases. The datasets from both databases were first coupled together, followed by column normalization. The Kennard-Stone algorithm was used to split the datasets into its training and test sets. Performance comparison based on the overall accuracy, sensitivity, specificity, and precision was conducted. Based on the overall accuracy of our classification scheme, the dictionary pair learning method was found to outperform the sub-dictionary learning methods 97.78% compared with 68.89%, respectively. Copyright © 2016 John Wiley & Sons, Ltd.

  5. Neural circuit mechanism for learning dependent on dopamine transmission: roles of striatal direct and indirect pathways in sensory discrimination.

    Science.gov (United States)

    Kobayashi, Kazuto; Fukabori, Ryoji; Nishizawa, Kayo

    2013-01-01

    The dorsal striatum in basal ganglia circuit mediates learning processes contributing to instrumental motor actions. The striatum receives excitatory inputs from many cortical areas and the thalamic nuclei and dopaminergic inputs from the ventral midbrain and projects to the output nuclei through direct and indirect pathways. The neural mechanism remains unclear as to how these striatofugal pathways control the learning processes of instrumental actions. Here, we addressed the behavioral roles of the two striatofugal pathways in the performance of sensory discrimination by using immunotoxin (IT)-mediated cell targeting. IT targeting of the striatal direct pathway in mutant mice lengthened the response time but did not affect the accuracy of the response selection in visual discrimination. Subregion-specific pathway targeting revealed a delay in motor responses generated by elimination of the direct pathway arising from the dorsomedial striatum (DMS) but not from the dorsolateral striatum (DLS). These findings indicate that the direct pathway, in particular that from the DMS, contributes to the regulation of the response time in visual discrimination. In addition, IT targeting of the striatal indirect pathway originating from the DLS in transgenic rats impaired the accuracy of response selection in auditory discrimination, whereas the response time remained normal. These data demonstrate that the DLS-derived indirect pathway plays an essential role in the control of the selection accuracy of learned motor responses. Our results suggest that striatal direct and indirect pathways act cooperatively to regulate the selection accuracy and response time of learned motor actions in the performance of discriminative learning.

  6. Working memory capacity predicts effects of methylphenidate on reversal learning.

    Science.gov (United States)

    van der Schaaf, Marieke E; Fallon, Sean J; Ter Huurne, Niels; Buitelaar, Jan; Cools, Roshan

    2013-09-01

    Increased use of stimulant medication, such as methylphenidate, by healthy college students has raised questions about its cognitive-enhancing effects. Methylphenidate acts by increasing extracellular catecholamine levels and is generally accepted to remediate cognitive and reward deficits in patients with attention deficit hyperactivity disorder. However, the cognitive-enhancing effects of such 'smart drugs' in the healthy population are still unclear. Here, we investigated effects of methylphenidate (Ritalin, 20  mg) on reward and punishment learning in healthy students (N=19) in a within-subject, double-blind, placebo-controlled cross-over design. Results revealed that methylphenidate effects varied both as a function of task demands and as a function of baseline working memory capacity. Specifically, methylphenidate improved reward vs punishment learning in high-working memory subjects, whereas it impaired reward vs punishment learning in low-working memory subjects. These results contribute to our understanding of individual differences in the cognitive-enhancing effects of methylphenidate in the healthy population. Moreover, they highlight the importance of taking into account both inter- and intra-individual differences in dopaminergic drug research.

  7. Cocaine use severity and cerebellar gray matter are associated with reversal learning deficits in cocaine-dependent individuals

    NARCIS (Netherlands)

    Moreno-López, L.; Perales, J.C.; van Son, D.; Albein-Urios, N.; Soriano-Mas, C.; Martinez-Gonzalez, J.M.; Wiers, R.W.; Verdejo-García, A.

    2015-01-01

    Cocaine addiction involves persistent deficits to unlearn previously rewarded response options, potentially due to neuroadaptations in learning-sensitive regions. Cocaine-targeted prefrontal systems have been consistently associated with reinforcement learning and reversal deficits, but more recent

  8. Cocaine use severity and cerebellar gray matter are associated with reversal learning deficits in cocaine-dependent individuals

    NARCIS (Netherlands)

    Moreno-López, L.; Perales, J.C.; van Son, D.; Albein-Urios, N.; Soriano-Mas, C.; Martinez-Gonzalez, J.M.; Wiers, R.W.; Verdejo-García, A.

    2015-01-01

    Cocaine addiction involves persistent deficits to unlearn previously rewarded response options, potentially due to neuroadaptations in learning-sensitive regions. Cocaine-targeted prefrontal systems have been consistently associated with reinforcement learning and reversal deficits, but more recent

  9. Discrimination of schizophrenia auditory hallucinators by machine learning of resting-state functional MRI.

    Science.gov (United States)

    Chyzhyk, Darya; Graña, Manuel; Öngür, Döst; Shinn, Ann K

    2015-05-01

    Auditory hallucinations (AH) are a symptom that is most often associated with schizophrenia, but patients with other neuropsychiatric conditions, and even a small percentage of healthy individuals, may also experience AH. Elucidating the neural mechanisms underlying AH in schizophrenia may offer insight into the pathophysiology associated with AH more broadly across multiple neuropsychiatric disease conditions. In this paper, we address the problem of classifying schizophrenia patients with and without a history of AH, and healthy control (HC) subjects. To this end, we performed feature extraction from resting state functional magnetic resonance imaging (rsfMRI) data and applied machine learning classifiers, testing two kinds of neuroimaging features: (a) functional connectivity (FC) measures computed by lattice auto-associative memories (LAAM), and (b) local activity (LA) measures, including regional homogeneity (ReHo) and fractional amplitude of low frequency fluctuations (fALFF). We show that it is possible to perform classification within each pair of subject groups with high accuracy. Discrimination between patients with and without lifetime AH was highest, while discrimination between schizophrenia patients and HC participants was worst, suggesting that classification according to the symptom dimension of AH may be more valid than discrimination on the basis of traditional diagnostic categories. FC measures seeded in right Heschl's gyrus (RHG) consistently showed stronger discriminative power than those seeded in left Heschl's gyrus (LHG), a finding that appears to support AH models focusing on right hemisphere abnormalities. The cortical brain localizations derived from the features with strong classification performance are consistent with proposed AH models, and include left inferior frontal gyrus (IFG), parahippocampal gyri, the cingulate cortex, as well as several temporal and prefrontal cortical brain regions. Overall, the observed findings suggest that

  10. Combining generative and discriminative models for semantic segmentation of CT scans via active learning.

    Science.gov (United States)

    Iglesias, Juan Eugenio; Konukoglu, Ender; Montillo, Albert; Tu, Zhuowen; Criminisi, Antonio

    2011-01-01

    This paper presents a new supervised learning framework for the efficient recognition and segmentation of anatomical structures in 3D computed tomography (CT), with as little training data as possible. Training supervised classifiers to recognize organs within CT scans requires a large number of manually delineated exemplar 3D images, which are very expensive to obtain. In this study, we borrow ideas from the field of active learning to optimally select a minimum subset of such images that yields accurate anatomy segmentation. The main contribution of this work is in designing a combined generative-discriminative model which: i) drives optimal selection of training data; and ii) increases segmentation accuracy. The optimal training set is constructed by finding unlabeled scans which maximize the disagreement between our two complementary probabilistic models, as measured by a modified version of the Jensen-Shannon divergence. Our algorithm is assessed on a database of 196 labeled clinical CT scans with high variability in resolution, anatomy, pathologies, etc. Quantitative evaluation shows that, compared with randomly selecting the scans to annotate, our method decreases the number of training images by up to 45%. Moreover, our generative model of body shape substantially increases segmentation accuracy when compared to either using the discriminative model alone or a generic smoothness prior (e.g. via a Markov Random Field).

  11. Enhanced discriminative fear learning of phobia-irrelevant stimuli in spider-fearful individuals

    Directory of Open Access Journals (Sweden)

    Carina eMosig

    2014-10-01

    Full Text Available Avoidance is considered as a central hallmark of all anxiety disorders. The acquisition and expression of avoidance which leads to the maintenance and exacerbation of pathological fear is closely linked to Pavlovian and operant conditioning processes. Changes in conditionability might represent a key feature of all anxiety disorders but the exact nature of these alterations might vary across different disorders. To date, no information is available on specific changes in conditionability for disorder-irrelevant stimuli in specific phobia (SP. The first aim of this study was to investigate changes in fear acquisition and extinction in spider-fearful individuals as compared to non-fearful participants by using the de novo fear conditioning paradigm. Secondly, we aimed to determine whether differences in the magnitude of context-dependent fear retrieval exist between spider-fearful and non-fearful individuals. Our findings point to an enhanced fear discrimination in spider-fearful individuals as compared to non-fearful individuals at both the physiological and subjective level. The enhanced fear discrimination in spider-fearful individuals was neither mediated by increased state anxiety, depression, nor stress tension. Spider-fearful individuals displayed no changes in extinction learning and/or fear retrieval. Surprisingly, we found no evidence for context-dependent modulation of fear retrieval in either group. Here we provide first evidence that spider-fearful individuals show an enhanced discriminative fear learning of phobia-irrelevant (de novo stimuli. Our findings provide novel insights into the role of fear acquisition and expression for the development and maintenance of maladaptive responses in the course of SP.

  12. Blockade of dopamine D₃ but not D₂ receptors reverses the novel object discrimination impairment produced by post-weaning social isolation: implications for schizophrenia and its treatment.

    Science.gov (United States)

    Watson, David J G; Marsden, Charles A; Millan, Mark J; Fone, Kevin C F

    2012-05-01

    Dopamine D₃ receptors are densely expressed in mesolimbic projection areas, and selective antagonists enhance cognition, consistent with their potential therapeutic use in the treatment of schizophrenia. This study examines the effect of dopamine D₃ vs. D₂ receptor antagonists on the cognitive impairment and hyperactivity produced by social isolation of rat pups, in a neurodevelopmental model of certain deficits of schizophrenia. Three separate groups of male Lister hooded rats were group-housed or isolation-reared from weaning. Six weeks later rats received either vehicle or the dopamine D₃ selective antagonist, S33084 (0.04 and 0.16 mg/kg), the preferential D₃ antagonist, S33138 (0.16 and 0.63 mg/kg) or the preferential D₂ antagonist, L-741,626 (0.63 mg/kg) s.c. 30 min prior to recording; horizontal locomotor activity in a novel arena for 60 min and, the following day, novel object discrimination using a 2-h inter-trial interval. Isolation rearing induced locomotor hyperactivity in a novel arena and impaired novel object discrimination compared to that in group-housed littermates. Both S33084 and S33138 restored novel object discrimination deficits in isolation-reared rats without affecting discrimination in group-housed controls. By contrast, L-741,626 impaired novel object discrimination in group-housed rats, without affecting impairment in isolates. S33084 (0.16 mg/kg), S33138 and, less markedly, L741,626 reduced the locomotor hyperactivity in isolates without attenuating activity in group-housed controls. Selective blockade of dopamine D₃ receptors reverses the visual recognition memory deficit and hyperactivity produced by isolation rearing. These data support further investigation of the potential use of dopamine D₃ receptor antagonists to treat schizophrenia.

  13. Feedback-related negativity codes prediction error but not behavioral adjustment during probabilistic reversal learning

    NARCIS (Netherlands)

    Chase, H.W.; Swainson, R.; Durham, L.; Benham, L.; Cools, R.

    2011-01-01

    We assessed electrophysiological activity over the medial frontal cortex (MFC) during outcome-based behavioral adjustment using a probabilistic reversal learning task. During recording, participants were presented two abstract visual patterns on each trial and had to select the stimulus rewarded on

  14. Concurrent recall of serially learned visual discrimination problems in dwarf goats (Capra hircus).

    Science.gov (United States)

    Langbein, J; Siebert, K; Nuernberg, G

    2008-11-01

    Studies of cognitive ability in farm animals are valuable, not only because they provide indicators of the commonality of comparative influence, but understanding farm animal cognition may also aid in management and treatment procedures. Here, eight dwarf goats (Capra hircus) learned a series of 10 visual four-choice discriminations using an automated device that allowed individual ad lib. access to the test setup while staying in a familiar environment and normal social setting. The animals were trained on each problem for 5 days, followed by concurrent testing of the current against the previous problem. Once all 10 problems had been learned, they were tested concurrently over the course of 9 days. In initial training, all goats achieved criterion learning levels on nearly all problems within 2 days and under 200 trials. Concurrently presenting the problems trained in adjacent sessions did not impair performance on either problem relative to single-problem learning. Upon concurrent presentation of all 10 previously learned problems, at least half were well-remembered immediately. Although this test revealed a recency effect (later problems were better remembered), many early-learned problems were also well-retained, and 10-item relearning was quite quick. These results show that dwarf goats can retain multiple-problem information proficiently and can do so over periods of several weeks. From an ecological point of view, the ability to form numerous associations between visual cues offered by specific plants and food quality is an important pre-grazing mechanism that helps goats exploit variation in vegetation and graze selectively.

  15. Effect of bilingualism on lexical stress pattern discrimination in French-learning infants.

    Directory of Open Access Journals (Sweden)

    Ranka Bijeljac-Babic

    Full Text Available Monolingual infants start learning the prosodic properties of their native language around 6 to 9 months of age, a fact marked by the development of preferences for predominant prosodic patterns and a decrease in sensitivity to non-native prosodic properties. The present study evaluates the effects of bilingual acquisition on speech perception by exploring how stress pattern perception may differ in French-learning 10-month-olds raised in bilingual as opposed to monolingual environments. Experiment 1 shows that monolinguals can discriminate stress patterns following a long familiarization to one of two patterns, but not after a short familiarization. In Experiment 2, two subgroups of bilingual infants growing up learning both French and another language (varying across infants in which stress is used lexically were tested under the more difficult short familiarization condition: one with balanced input, and one receiving more input in the language other than French. Discrimination was clearly found for the other-language-dominant subgroup, establishing heightened sensitivity to stress pattern contrasts in these bilinguals as compared to monolinguals. However, the balanced bilinguals' performance was not better than that of monolinguals, establishing an effect of the relative balance of the language input. This pattern of results is compatible with the proposal that sensitivity to prosodic contrasts is maintained or enhanced in a bilingual population compared to a monolingual population in which these contrasts are non-native, provided that this dimension is used in one of the two languages in acquisition, and that infants receive enough input from that language.

  16. Training haptic stiffness discrimination: time course of learning with or without visual information and knowledge of results.

    Science.gov (United States)

    Teodorescu, Kinneret; Bouchigny, Sylvain; Korman, Maria

    2013-08-01

    In this study, we explored the time course of haptic stiffness discrimination learning and how it was affected by two experimental factors, the addition of visual information and/or knowledge of results (KR) during training. Stiffness perception may integrate both haptic and visual modalities. However, in many tasks, the visual field is typically occluded, forcing stiffness perception to be dependent exclusively on haptic information. No studies to date addressed the time course of haptic stiffness perceptual learning. Using a virtual environment (VE) haptic interface and a two-alternative forced-choice discrimination task, the haptic stiffness discrimination ability of 48 participants was tested across 2 days. Each day included two haptic test blocks separated by a training block Additional visual information and/or KR were manipulated between participants during training blocks. Practice repetitions alone induced significant improvement in haptic stiffness discrimination. Between days, accuracy was slightly improved, but decision time performance was deteriorated. The addition of visual information and/or KR had only temporary effects on decision time, without affecting the time course of haptic discrimination learning. Learning in haptic stiffness discrimination appears to evolve through at least two distinctive phases: A single training session resulted in both immediate and latent learning. This learning was not affected by the training manipulations inspected. Training skills in VE in spaced sessions can be beneficial for tasks in which haptic perception is critical, such as surgery procedures, when the visual field is occluded. However, training protocols for such tasks should account for low impact of multisensory information and KR.

  17. Corpus linguistics and naive discriminative learning A linguística de corpus e a aprendizagem discriminativa ingênua

    Directory of Open Access Journals (Sweden)

    R. Harald Baayen

    2011-01-01

    Full Text Available Three classifiers from machine learning (the generalized linear mixed model, memory based learning, and support vector machines are compared with a naive discriminative learning classifier, derived from basic principles of error-driven learning characterizing animal and human learning. Tested on the dative alternation in English, using the Switchboard data from (BRESNAN; CUENI; NIKITINA; BAAYEN, 2007, naive discriminative learning emerges with stateof-the-art predictive accuracy. Naive discriminative learning offers a united framework for understanding the learning of probabilistic distributional patterns, for classification, and for a cognitive grounding of distinctive collexeme analysis.Três classificadores de aprendizagem de máquina (modelos mistos lineares generalizados, aprendizagem baseada na memória e máquinas de apoio a vetores são comparados com o classificador da aprendizagem discriminativa ingênua, derivada de princípios básicos da aprendizagem guiada por erros de humanos e animais. Testada na alternância dativa do inglês, usando os dados do Switchboard (BRESNAN; CUENI; NIKITINA; BAAYEN, 2007, a aprendizagem discriminativa ingênua emerge com uma acurácia predicativa no estado da arte. A aprendizagem discriminativa ingênua oferece um arcabouço unificado para a compreensão da aprendizagem de padrões distribucionais probabilísticos, para a classificação, e para um embasamento cognitivo para a análise de colexemas distintivos.

  18. Withdrawal from Cocaine Self-Administration Produces Long-Lasting Deficits in Orbitofrontal-Dependent Reversal Learning in Rats

    Science.gov (United States)

    Calu, Donna J.; Stalnaker, Thomas A.; Franz, Theresa M.; Singh, Teghpal; Shaham, Yavin; Schoenbaum, Geoffrey

    2007-01-01

    Drug addicts make poor decisions. These decision-making deficits have been modeled in addicts and laboratory animals using reversal-learning tasks. However, persistent reversal-learning impairments have been shown in rats and monkeys only after noncontingent cocaine injections. Current thinking holds that to represent the human condition…

  19. Acute effects of cocaine and cannabis on reversal learning as a function of COMT and DRD2 genotype.

    Science.gov (United States)

    Spronk, Desirée B; Van der Schaaf, Marieke E; Cools, Roshan; De Bruijn, Ellen R A; Franke, Barbara; van Wel, Janelle H P; Ramaekers, Johannes G; Verkes, Robbert J

    2016-01-01

    Long-term cannabis and cocaine use has been associated with impairments in reversal learning. However, how acute cannabis and cocaine administration affect reversal learning in humans is not known. In this study, we aimed to establish the acute effects of administration of cannabis and cocaine on valence-dependent reversal learning as a function of DRD2 Taq1A (rs1800497) and COMT Val108/158Met (rs4680) genotype. A double-blind placebo-controlled randomized 3-way crossover design was used. Sixty-one regular poly-drug users completed a deterministic reversal learning task under the influence of cocaine, cannabis, and placebo that enabled assessment of both reward- and punishment-based reversal learning. Proportion correct on the reversal learning task was increased by cocaine, but decreased by cannabis. Effects of cocaine depended on the DRD2 genotype, as increases in proportion correct were seen only in the A1 carriers, and not in the A2/A2 homozygotes. COMT genotype did not modulate drug-induced effects on reversal learning. These data indicate that acute administration of cannabis and cocaine has opposite effects on reversal learning. The effects of cocaine, but not cannabis, depend on interindividual genetic differences in the dopamine D2 receptor gene.

  20. Synaptic proteome changes in mouse brain regions upon auditory discrimination learning.

    Science.gov (United States)

    Kähne, Thilo; Kolodziej, Angela; Smalla, Karl-Heinz; Eisenschmidt, Elke; Haus, Utz-Uwe; Weismantel, Robert; Kropf, Siegfried; Wetzel, Wolfram; Ohl, Frank W; Tischmeyer, Wolfgang; Naumann, Michael; Gundelfinger, Eckart D

    2012-08-01

    Changes in synaptic efficacy underlying learning and memory processes are assumed to be associated with alterations of the protein composition of synapses. Here, we performed a quantitative proteomic screen to monitor changes in the synaptic proteome of four brain areas (auditory cortex, frontal cortex, hippocampus striatum) during auditory learning. Mice were trained in a shuttle box GO/NO-GO paradigm to discriminate between rising and falling frequency modulated tones to avoid mild electric foot shock. Control-treated mice received corresponding numbers of either the tones or the foot shocks. Six hours and 24 h later, the composition of a fraction enriched in synaptic cytomatrix-associated proteins was compared to that obtained from naïve mice by quantitative mass spectrometry. In the synaptic protein fraction obtained from trained mice, the average percentage (±SEM) of downregulated proteins (59.9 ± 0.5%) exceeded that of upregulated proteins (23.5 ± 0.8%) in the brain regions studied. This effect was significantly smaller in foot shock (42.7 ± 0.6% down, 40.7 ± 1.0% up) and tone controls (43.9 ± 1.0% down, 39.7 ± 0.9% up). These data suggest that learning processes initially induce removal and/or degradation of proteins from presynaptic and postsynaptic cytoskeletal matrices before these structures can acquire a new, postlearning organisation. In silico analysis points to a general role of insulin-like signalling in this process.

  1. Discriminative Manifold Learning Based Detection of Movement-Related Cortical Potentials.

    Science.gov (United States)

    Lin, Chuang; Wang, Bing-Hui; Jiang, Ning; Xu, Ren; Mrachacz-Kersting, Natalie; Farina, Dario

    2016-09-01

    The detection of voluntary motor intention from EEG has been applied to closed-loop brain-computer interfacing (BCI). The movement-related cortical potential (MRCP) is a low frequency component of the EEG signal, which represents movement intention, preparation, and execution. In this study, we aim at detecting MRCPs from single-trial EEG traces. For this purpose, we propose a detector based on a discriminant manifold learning method, called locality sensitive discriminant analysis (LSDA), and we test it in both online and offline experiments with executed and imagined movements. The online and offline experimental results demonstrated that the proposed LSDA approach for MRCP detection outperformed the Locality Preserving Projection (LPP) approach, which was previously shown to be the most accurate algorithm so far tested for MRCP detection. For example, in the online tests, the performance of LSDA was superior than LPP in terms of a significant reduction in false positives (FP) (passive FP: 1.6 ±0.9/min versus 2.9 ±1.0/min, p = 0.002, active FP: 2.2 ±0.8/min versus 2.7 ±0.6/min , p = 0.03 ), for a similar rate of true positives. In conclusion, the proposed LSDA based MRCP detection method is superior to previous approaches and is promising for developing patient-driven BCI systems for motor function rehabilitation as well as for neuroscience research.

  2. Deep learning in color: towards automated quark/gluon jet discrimination

    Science.gov (United States)

    Komiske, Patrick T.; Metodiev, Eric M.; Schwartz, Matthew D.

    2017-01-01

    Artificial intelligence offers the potential to automate challenging data-processing tasks in collider physics. To establish its prospects, we explore to what extent deep learning with convolutional neural networks can discriminate quark and gluon jets better than observables designed by physicists. Our approach builds upon the paradigm that a jet can be treated as an image, with intensity given by the local calorimeter deposits. We supplement this construction by adding color to the images, with red, green and blue intensities given by the transverse momentum in charged particles, transverse momentum in neutral particles, and pixel-level charged particle counts. Overall, the deep networks match or outperform traditional jet variables. We also find that, while various simulations produce different quark and gluon jets, the neural networks are surprisingly insensitive to these differences, similar to traditional observables. This suggests that the networks can extract robust physical information from imperfect simulations.

  3. Efficient Approximation of the Conditional Relative Entropy with Applications to Discriminative Learning of Bayesian Network Classifiers

    Directory of Open Access Journals (Sweden)

    Paulo Mateus

    2013-07-01

    Full Text Available We propose a minimum variance unbiased approximation to the conditional relative entropy of the distribution induced by the observed frequency estimates, for multi-classification tasks. Such approximation is an extension of a decomposable scoring criterion, named approximate conditional log-likelihood (aCLL, primarily used for discriminative learning of augmented Bayesian network classifiers. Our contribution is twofold: (i it addresses multi-classification tasks and not only binary-classification ones; and (ii it covers broader stochastic assumptions than uniform distribution over the parameters. Specifically, we considered a Dirichlet distribution over the parameters, which was experimentally shown to be a very good approximation to CLL. In addition, for Bayesian network classifiers, a closed-form equation is found for the parameters that maximize the scoring criterion.

  4. Statistical and Machine-Learning Classifier Framework to Improve Pulse Shape Discrimination System Design

    Energy Technology Data Exchange (ETDEWEB)

    Wurtz, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kaplan, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-10-28

    Pulse shape discrimination (PSD) is a variety of statistical classifier. Fully-­realized statistical classifiers rely on a comprehensive set of tools for designing, building, and implementing. PSD advances rely on improvements to the implemented algorithm. PSD advances can be improved by using conventional statistical classifier or machine learning methods. This paper provides the reader with a glossary of classifier-­building elements and their functions in a fully-­designed and operational classifier framework that can be used to discover opportunities for improving PSD classifier projects. This paper recommends reporting the PSD classifier’s receiver operating characteristic (ROC) curve and its behavior at a gamma rejection rate (GRR) relevant for realistic applications.

  5. Selective increase of auditory cortico-striatal coherence during auditory-cued Go/NoGo discrimination learning.

    Directory of Open Access Journals (Sweden)

    Andreas L. Schulz

    2016-01-01

    Full Text Available Goal directed behavior and associated learning processes are tightly linked to neuronal activity in the ventral striatum. Mechanisms that integrate task relevant sensory information into striatal processing during decision making and learning are implicitly assumed in current reinforcementmodels, yet they are still weakly understood. To identify the functional activation of cortico-striatal subpopulations of connections during auditory discrimination learning, we trained Mongolian gerbils in a two-way active avoidance task in a shuttlebox to discriminate between falling and rising frequency modulated tones with identical spectral properties. We assessed functional coupling by analyzing the field-field coherence between the auditory cortex and the ventral striatum of animals performing the task. During the course of training, we observed a selective increase of functionalcoupling during Go-stimulus presentations. These results suggest that the auditory cortex functionally interacts with the ventral striatum during auditory learning and that the strengthening of these functional connections is selectively goal-directed.

  6. Protective effect of the calcium antagonist nimodipine on discrimination learning deficits and impaired retention behavior caused by prenatal nitrite exposure in rats

    NARCIS (Netherlands)

    Nyakas, Csaba; Markel, Éva; Bohus, Béla; Schuurman, Teun; Luiten, Paulus

    1990-01-01

    Discrimination learning behavior and retention of a passive avoidance response were studied in male adult offspring of gestating rats exposed to drinking water containing 2 g/l sodium nitrite, throughout the second half of pregnancy. Both in an auditory and visual discrimination learning paradigm Na

  7. Effects of acute sleep deprivation on motor and reversal learning in mice.

    Science.gov (United States)

    Varga, Andrew W; Kang, Mihwa; Ramesh, Priyanka V; Klann, Eric

    2014-10-01

    Sleep supports the formation of a variety of declarative and non-declarative memories, and sleep deprivation often impairs these types of memories. In human subjects, natural sleep either during a nap or overnight leads to long-lasting improvements in visuomotor and fine motor tasks, but rodent models recapitulating these findings have been scarce. Here we present evidence that 5h of acute sleep deprivation impairs mouse skilled reach learning compared to a matched period of ad libitum sleep. In sleeping mice, the duration of total sleep time during the 5h of sleep opportunity or during the first bout of sleep did not correlate with ultimate gain in motor performance. In addition, we observed that reversal learning during the skilled reaching task was also affected by sleep deprivation. Consistent with this observation, 5h of sleep deprivation also impaired reversal learning in the water-based Y-maze. In conclusion, acute sleep deprivation negatively impacts subsequent motor and reversal learning and memory. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. Age-related similarities and differences in brain activity underlying reversal learning

    Directory of Open Access Journals (Sweden)

    Kaoru eNashiro

    2013-05-01

    Full Text Available The ability to update associative memory is an important aspect of episodic memory and a critical skill for social adaptation. Previous research with younger adults suggests that emotional arousal alters brain mechanisms underlying memory updating; however, it is unclear whether this applies to older adults. Given that the ability to update associative information declines with age, it is important to understand how emotion modulates the brain processes underlying memory updating in older adults. The current study investigated this question using reversal learning tasks, where younger and older participants (age ranges 19-35 and 61-78 respectively learn a stimulus–outcome association and then update their response when contingencies change. We found that younger and older adults showed similar patterns of activation in the frontopolar OFC and the amygdala during emotional reversal learning. In contrast, when reversal learning did not involve emotion, older adults showed greater parietal cortex activity than did younger adults. Thus, younger and older adults show more similarities in brain activity during memory updating involving emotional stimuli than during memory updating not involving emotional stimuli.

  9. Distinct discrimination learning strategies and their relation with spatial memory and attentional control in 4- to 14-year-olds.

    Science.gov (United States)

    Schmittmann, Verena D; van der Maas, Han L J; Raijmakers, Maartje E J

    2012-04-01

    Behavioral, psychophysiological, and neuropsychological studies have revealed large developmental differences in various learning paradigms where learning from positive and negative feedback is essential. The differences are possibly due to the use of distinct strategies that may be related to spatial working memory and attentional control. In this study, strategies in performing a discrimination learning task were distinguished in a cross-sectional sample of 302 children from 4 to 14 years of age. The trial-by-trial accuracy data were analyzed with mathematical learning models. The best-fitting model revealed three learning strategies: hypothesis testing, slow abrupt learning, and nonlearning. The proportion of hypothesis-testing children increased with age. Nonlearners were present only in the youngest age group. Feature preferences for the irrelevant dimension had a detrimental effect on performance in the youngest age group. The executive functions spatial working memory and attentional control significantly predicted posterior learning strategy probabilities after controlling for age.

  10. Regionally distinct phasic dopamine release patterns in the striatum during reversal learning.

    Science.gov (United States)

    Klanker, Marianne; Fellinger, Lisanne; Feenstra, Matthijs; Willuhn, Ingo; Denys, Damiaan

    2017-03-14

    Striatal dopamine (DA) plays a central role in reward-related learning and behavioral adaptation to changing environments. Recent studies suggest that rather than being broadcast as a uniform signal throughout the entire region, DA release dynamics diverge between different striatal regions. In a previous study, we showed that phasic DA release patterns in the ventromedial striatum (VMS) rapidly adapt during reversal learning. However, it is unknown how DA dynamics in the dorsolateral striatum (DLS) are modulated during such adaptive behavior. Here, we used fast-scan cyclic voltammetry to measure phasic DA release in the DLS during spatial reversal learning. In the DLS, we observed minor DA release after the onset of a visual cue signaling reward availability, followed by more pronounced DA release during more proximal reward cues (e.g., lever extension) and execution of the operant response (i.e., lever press), both in rewarded and non-rewarded trials. These release dynamics (minor DA after onset of the predictive visual cue, prominent DA during the operant response) did not change significantly during or following a reversal of response-reward contingencies. Notably, the DA increase to the lever press did not reflect a general signal related to the initiation of any motivated motor response, as we did not observe DA release when rats initiated nose pokes into the food receptacle during inter-trial intervals. This suggests that DA release in the DLS occurs selectively during the initiation and execution of a learned operant response. Together with our previous results obtained in the VMS, these findings reveal distinct phasic DA release patterns during adaptation of established behavior in DLS and VMS. The VMS DA signal, which is highly sensitive to reversal of response-reward contingences, may provide a teaching signal to guide reward-related learning and facilitate behavioral adaptation, whereas DLS DA may reflect a 'response execution signal' largely

  11. Discriminative learning of receptive fields from responses to non-Gaussian stimulus ensembles.

    Directory of Open Access Journals (Sweden)

    Arne F Meyer

    Full Text Available Analysis of sensory neurons' processing characteristics requires simultaneous measurement of presented stimuli and concurrent spike responses. The functional transformation from high-dimensional stimulus space to the binary space of spike and non-spike responses is commonly described with linear-nonlinear models, whose linear filter component describes the neuron's receptive field. From a machine learning perspective, this corresponds to the binary classification problem of discriminating spike-eliciting from non-spike-eliciting stimulus examples. The classification-based receptive field (CbRF estimation method proposed here adapts a linear large-margin classifier to optimally predict experimental stimulus-response data and subsequently interprets learned classifier weights as the neuron's receptive field filter. Computational learning theory provides a theoretical framework for learning from data and guarantees optimality in the sense that the risk of erroneously assigning a spike-eliciting stimulus example to the non-spike class (and vice versa is minimized. Efficacy of the CbRF method is validated with simulations and for auditory spectro-temporal receptive field (STRF estimation from experimental recordings in the auditory midbrain of Mongolian gerbils. Acoustic stimulation is performed with frequency-modulated tone complexes that mimic properties of natural stimuli, specifically non-Gaussian amplitude distribution and higher-order correlations. Results demonstrate that the proposed approach successfully identifies correct underlying STRFs, even in cases where second-order methods based on the spike-triggered average (STA do not. Applied to small data samples, the method is shown to converge on smaller amounts of experimental recordings and with lower estimation variance than the generalized linear model and recent information theoretic methods. Thus, CbRF estimation may prove useful for investigation of neuronal processes in response to

  12. Discriminative Learning of Receptive Fields from Responses to Non-Gaussian Stimulus Ensembles

    Science.gov (United States)

    Meyer, Arne F.; Diepenbrock, Jan-Philipp; Happel, Max F. K.; Ohl, Frank W.; Anemüller, Jörn

    2014-01-01

    Analysis of sensory neurons' processing characteristics requires simultaneous measurement of presented stimuli and concurrent spike responses. The functional transformation from high-dimensional stimulus space to the binary space of spike and non-spike responses is commonly described with linear-nonlinear models, whose linear filter component describes the neuron's receptive field. From a machine learning perspective, this corresponds to the binary classification problem of discriminating spike-eliciting from non-spike-eliciting stimulus examples. The classification-based receptive field (CbRF) estimation method proposed here adapts a linear large-margin classifier to optimally predict experimental stimulus-response data and subsequently interprets learned classifier weights as the neuron's receptive field filter. Computational learning theory provides a theoretical framework for learning from data and guarantees optimality in the sense that the risk of erroneously assigning a spike-eliciting stimulus example to the non-spike class (and vice versa) is minimized. Efficacy of the CbRF method is validated with simulations and for auditory spectro-temporal receptive field (STRF) estimation from experimental recordings in the auditory midbrain of Mongolian gerbils. Acoustic stimulation is performed with frequency-modulated tone complexes that mimic properties of natural stimuli, specifically non-Gaussian amplitude distribution and higher-order correlations. Results demonstrate that the proposed approach successfully identifies correct underlying STRFs, even in cases where second-order methods based on the spike-triggered average (STA) do not. Applied to small data samples, the method is shown to converge on smaller amounts of experimental recordings and with lower estimation variance than the generalized linear model and recent information theoretic methods. Thus, CbRF estimation may prove useful for investigation of neuronal processes in response to natural stimuli and

  13. Discriminating Children with Autism from Children with Learning Difficulties with an Adaptation of the Short Sensory Profile

    Science.gov (United States)

    O'Brien, Justin; Tsermentseli, Stella; Cummins, Omar; Happe, Francesca; Heaton, Pamela; Spencer, Janine

    2009-01-01

    In this article, we examine the extent to which children with autism and children with learning difficulties can be discriminated from their responses to different patterns of sensory stimuli. Using an adapted version of the Short Sensory Profile (SSP), sensory processing was compared in 34 children with autism to 33 children with typical…

  14. The Effects of Pre- and Post-Choice Verbalization Instructions on Discrimination Learning in Young Children. Technical Report.

    Science.gov (United States)

    Wilder, Larry; Norton, Richard W.

    A total of 48 fifth-grade and 30 nursery-school subjects were administered picture pairs in a discrimination learning experiment. In addition to a control group, one group of subjects (pre-choice) was instructed to pronounce both items before choosing one, and another group (post-choice) was told to say both items after choosing one. The…

  15. Achievement of Specificational Information Usage with True and False Feedback in Learning a Visual Relative-Mass Discrimination Task

    Science.gov (United States)

    Runeson, Sverker; Andersson, Isabell E. K.

    2007-01-01

    Participants' usage of informational variables in learning visual relative-mass discrimination in collisions was tracked by means of PROBIT correlations. Four groups received feedback that was true or accorded with either of three nonspecificational cue variables. A majority in each group adopted the feedback, but several participants defied the…

  16. Effects of risperidone, clozapine and the 5-HT6 antagonist GSK-742457 on PCP-induced deficits in reversal learning in the two-lever operant task in male Sprague Dawley rats.

    Science.gov (United States)

    de Bruin, N M W J; van Drimmelen, M; Kops, M; van Elk, J; Wetering, M Middelveld-van de; Schwienbacher, I

    2013-05-01

    Reasoning and problem solving deficits have been reported in schizophrenic patients. In the present study, we have tested rats in a two-lever reversal learning task in a Skinner box to model these deficits. In other studies using the Skinner box, atypical antipsychotics fully reversed phencyclidine (PCP)-induced impairments in reversal learning which is in contrast to clinical observations where antipsychotics lack the ability to fully reverse cognitive deficits in schizophrenia. Therefore, it can be argued that the outcome of these tests may lack predictive value. In the present study, after training on a spatial discrimination between two levers, rats were exposed to a reversal of the previously learned stimulus-response contingency during 5 days. We first investigated the effects of sub-chronic treatment with the non-competitive N-methyl-d-aspartate (NMDA) antagonists dizocilpine (MK-801) and PCP on reversal learning and extinction in male Sprague Dawley rats. Subsequently, we studied the effects of different PCP treatment regimes. Then, we investigated whether the atypical antipsychotics risperidone and clozapine and the 5-hydroxytryptamine6 (5-HT6) antagonist GSK-742457 could reverse the PCP-induced deficits. All drugs were administered subcutaneously (s.c.). MK-801 did not impair reversal learning, while PCP (1.0 and 2.0 mg/kg) induced a clear deficit in reversal learning. Both compounds, however, disrupted extinction at all tested doses. Risperidone and clozapine were both ineffective in significantly ameliorating the PCP-induced deficit in reversal learning which fits well with the clinical observations. The lowest dose of clozapine (1.25 mg/kg) had an intermediate effect in ameliorating the deficit in reversal learning induced by PCP (not different from control or PCP-treated rats). The lowest dose of GSK-742457 (0.63 mg/kg) fully reversed the PCP-induced deficits while the higher dose (5.0 mg/kg) had an intermediate effect. Copyright © 2013 Elsevier B

  17. Improved object optimal synthetic description, modeling, learning, and discrimination by GEOGINE computational kernel

    Science.gov (United States)

    Fiorini, Rodolfo A.; Dacquino, Gianfranco

    2005-03-01

    GEOGINE (GEOmetrical enGINE), a state-of-the-art OMG (Ontological Model Generator) based on n-D Tensor Invariants for n-Dimensional shape/texture optimal synthetic representation, description and learning, was presented in previous conferences elsewhere recently. Improved computational algorithms based on the computational invariant theory of finite groups in Euclidean space and a demo application is presented. Progressive model automatic generation is discussed. GEOGINE can be used as an efficient computational kernel for fast reliable application development and delivery in advanced biomedical engineering, biometric, intelligent computing, target recognition, content image retrieval, data mining technological areas mainly. Ontology can be regarded as a logical theory accounting for the intended meaning of a formal dictionary, i.e., its ontological commitment to a particular conceptualization of the world object. According to this approach, "n-D Tensor Calculus" can be considered a "Formal Language" to reliably compute optimized "n-Dimensional Tensor Invariants" as specific object "invariant parameter and attribute words" for automated n-Dimensional shape/texture optimal synthetic object description by incremental model generation. The class of those "invariant parameter and attribute words" can be thought as a specific "Formal Vocabulary" learned from a "Generalized Formal Dictionary" of the "Computational Tensor Invariants" language. Even object chromatic attributes can be effectively and reliably computed from object geometric parameters into robust colour shape invariant characteristics. As a matter of fact, any highly sophisticated application needing effective, robust object geometric/colour invariant attribute capture and parameterization features, for reliable automated object learning and discrimination can deeply benefit from GEOGINE progressive automated model generation computational kernel performance. Main operational advantages over previous

  18. Neural correlates of short-term perceptual learning in orientation discrimination indexed by event-related potentials

    Institute of Scientific and Technical Information of China (English)

    SONG Yan; PENG DanLing; LI XiaoLan; ZHANG Yi; KANG Jing; QU Zhe; DING YuLong

    2007-01-01

    The current work investigated the neural correlates of visual perceptual learning in grating orientation discrimination by recording event-related potentials (ERPs) from human adults. Subjects were trained with a discrimination task of grating orientation in three consecutive training sessions within 2 h. While reaction times (RTs) were shortened gradually across training sessions, the N1 was decreased and the P2 was increased over the parietal and occipital areas. A broadly distributed P3 was increased along with more practices. In addition, the time course of learning reflected in the P2 and P3 amplitudes was in line with the changes of reaction times and exhibited a stable level during later training. The implications of these results to the neural mechanisms subserving perceptual learning were discussed.

  19. [Drug discrimination by near infrared spectroscopy based on summation wavelet extreme learning machine].

    Science.gov (United States)

    Liu, Zhen-Bing; Jiang, Shu-Jie; Yang, Hui-Hua; Zhang, Xue-Bo

    2014-10-01

    As an effective technique to identify counterfeit drugs, Near Infrared Spectroscopy has been successfully used in the drug management of grass-roots units, with classifier modeling of Pattern Recognition. Due to a major disadvantage of the characteristic overlap and complexity, the wide bandwidth and the weak absorption of the Spectroscopy signals, it seems difficult to give a satisfactory solutions for the modeling problem. To address those problems, in the present paper, a summation wavelet extreme learning machine algorithm (SWELM(CS)) combined with Cuckoo research was adopted for drug discrimination by NIRS. Specifically, Extreme Learning Machine (ELM) was selected as the classifier model because of its properties of fast learning and insensitivity, to improve the accuracy and generalization performances of the classifier model; An inverse hyperbolic sine and a Morlet-wavelet are used as dual activation functions to improve convergence speed, and a combination of activation functions makes the network more adequate to deal with dynamic systems; Due to ELM' s weights and hidden layer threshold generated randomly, it leads to network instability, so Cuckoo Search was adapted to optimize model parameters; SWELM(CS) improves stability of the classifier model. Besides, SWELM(CS) is based on the ELM algorithm for fast learning and insensitivity; the dual activation functions and proper choice of activation functions enhances the capability of the network to face low and high frequency signals simultaneously; it has high stability of classification by Cuckoo Research. This compact structure of the dual activation functions constitutes a kernel framework by extracting signal features and signal simultaneously, which can be generalized to other machine learning fields to obtain a good accuracy and generalization performances. Drug samples of near in- frared spectroscopy produced by Xian-Janssen Pharmaceutical Ltd were adopted as the main objects in this paper

  20. Post-learning REM sleep deprivation impairs long-term memory: reversal by acute nicotine treatment.

    Science.gov (United States)

    Aleisa, A M; Alzoubi, K H; Alkadhi, K A

    2011-07-15

    Rapid eye movement sleep deprivation (REM-SD) is associated with spatial learning and memory impairment. During REM-SD, an increase in nicotine consumption among habitual smokers and initiation of tobacco use by non-smokers have been reported. We have shown recently that nicotine treatment prevented learning and memory impairments associated with REM-SD. We now report the interactive effects of post-learning REM-SD and/or nicotine. The animals were first trained on the radial arm water maze (RAWM) task, then they were REM-sleep deprived using the modified multiple platform paradigm for 24h. During REM-SD period, the rats were injected with saline or nicotine (1mg/kg s.c. every 12h: a total of 3 injections). The animals were tested for long-term memory in the RAWM at the end of the REM-SD period. The 24h post-learning REM-SD significantly impaired long-term memory. However, nicotine treatment reversed the post-learning REM-SD-induced impairment of long-term memory. On the other hand, post-learning treatment of normal rats with nicotine for 24h enhanced long-term memory. These results indicate that post-learning acute nicotine treatment prevented the deleterious effect of REM-SD on cognitive abilities.

  1. The relationship between pronunciation and listening discrimination when Japanese natives are learning English

    OpenAIRE

    Shimamune, Satoru; Smith, Stacey L.

    1995-01-01

    Two Japanese students were taught to pronounce and discriminate English words that contain unfamiliar phonemic contrasts (e.g., rock and lock). Teaching pronunciation was found to be easier than teaching listening discrimination. Teaching listening discrimination resulted in collateral improvement in pronunciation and, to a lesser extent, vice versa.

  2. The relationship between pronunciation and listening discrimination when Japanese natives are learning English.

    Science.gov (United States)

    Shimamune, S; Smith, S L

    1995-01-01

    Two Japanese students were taught to pronounce and discriminate English words that contain unfamiliar phonemic contrasts (e.g., rock and lock). Teaching pronunciation was found to be easier than teaching listening discrimination. Teaching listening discrimination resulted in collateral improvement in pronunciation and, to a lesser extent, vice versa.

  3. Utility of California Verbal Learning Test, Second Edition, recall discriminability indices in the evaluation of traumatic brain injury.

    Science.gov (United States)

    Donders, Jacobus; Nienhuis, Jacob B

    2007-03-01

    The performance of 23 patients with moderate-severe traumatic brain injury on the California Verbal Learning Test, Second Edition (CVLT-II; Delis et al., 2000) was compared with that of 23 matched healthy controls to determine whether recall discriminability indices, which take into account both correct target recall and intrusive errors, would provide better diagnostic classification than traditional variables that are based exclusively on correct recall. Patients with traumatic brain injury recalled fewer correct words, and also made more intrusive errors, on CVLT-II short and long delay, free and cued recall trials (p recall discriminability indices yielded a classification of clinical versus control participants (72%) that was not significantly different from one based on traditional variables (74%). We conclude that CVLT-II recall discriminability indices do not routinely provide an advantage over traditional variables in patients with traumatic brain injury.

  4. Reversal learning and associative memory impairments in a BACHD rat model for Huntington disease.

    Directory of Open Access Journals (Sweden)

    Yah-Se K Abada

    Full Text Available Chorea and psychiatric symptoms are hallmarks of Huntington disease (HD, a neurodegenerative disorder, genetically characterized by the presence of expanded CAG repeats (>35 in the Huntingtin (HTT gene. HD patients present psychiatric symptoms prior to the onset of motor symptoms and we recently found a similar emergence of non motor and motor deficits in BACHD rats carrying the human full length mutated HTT (97 CAG-CAA repeats. We evaluated cognitive performance in reversal learning and associative memory tests in different age cohorts of BACHD rats. Male wild type (WT and transgenic (TG rats between 2 and 12 months of age were tested. Learning and strategy shifting were assessed in a cross-maze test. Associative memory was evaluated in different fear conditioning paradigms (context, delay and trace. The possible confound of a fear conditioning phenotype by altered sensitivity to a 'painful' stimulus was assessed in a flinch-jump test. In the cross maze, 6 months old TG rats showed a mild impairment in reversal learning. In the fear conditioning tasks, 4, 6 and 12 months old TG rats showed a marked reduction in contextual fear conditioning. In addition, TG rats showed impaired delay conditioning (9 months and trace fear conditioning (3 months. This phenotype was unlikely to be affected by a change in 'pain' sensitivity as WT and TG rats showed no difference in their threshold response in the flinch-jump test. Our results suggest that BACHD rats have a profound associative memory deficit and, possibly, a deficit in reversal learning as assessed in a cross maze task. The time course for the emergence of these symptoms (i.e., before the occurrence of motor symptoms in this rat model for HD appears similar to the time course in patients. These data suggest that BACHD rats may be a useful model for preclinical drug discovery.

  5. Discriminating cognitive status in Parkinson’s disease through functional connectomics and machine learning

    Science.gov (United States)

    Abós, Alexandra; Baggio, Hugo C.; Segura, Bàrbara; García-Díaz, Anna I.; Compta, Yaroslau; Martí, Maria José; Valldeoriola, Francesc; Junqué, Carme

    2017-01-01

    There is growing interest in the potential of neuroimaging to help develop non-invasive biomarkers in neurodegenerative diseases. In this study, connection-wise patterns of functional connectivity were used to distinguish Parkinson’s disease patients according to cognitive status using machine learning. Two independent subject samples were assessed with resting-state fMRI. The first (training) sample comprised 38 healthy controls and 70 Parkinson’s disease patients (27 with mild cognitive impairment). The second (validation) sample included 25 patients (8 with mild cognitive impairment). The Brainnetome atlas was used to reconstruct the functional connectomes. Using a support vector machine trained on features selected through randomized logistic regression with leave-one-out cross-validation, a mean accuracy of 82.6% (p < 0.002) was achieved in separating patients with mild cognitive impairment from those without it in the training sample. The model trained on the whole training sample achieved an accuracy of 80.0% when used to classify the validation sample (p = 0.006). Correlation analyses showed that the connectivity level in the edges most consistently selected as features was associated with memory and executive function performance in the patient group. Our results demonstrate that connection-wise patterns of functional connectivity may be useful for discriminating Parkinson’s disease patients according to the presence of cognitive deficits. PMID:28349948

  6. Multi-modal discriminative dictionary learning for Alzheimer's disease and mild cognitive impairment.

    Science.gov (United States)

    Li, Qing; Wu, Xia; Xu, Lele; Chen, Kewei; Yao, Li; Li, Rui

    2017-10-01

    The differentiation of mild cognitive impairment (MCI), which is the prodromal stage of Alzheimer's disease (AD), from normal control (NC) is important as the recent research emphasis on early pre-clinical stage for possible disease abnormality identification, intervention and even possible prevention. The current study puts forward a multi-modal supervised within-class-similarity discriminative dictionary learning algorithm (SCDDL) we introduced previously for distinguishing MCI from NC. The proposed new algorithm was based on weighted combination and named as multi-modality SCDDL (mSCDDL). Structural magnetic resonance imaging (sMRI), fluorodeoxyglucose (FDG) positron emission tomography (PET) and florbetapir PET data of 113 AD patients, 110 MCI patients and 117 NC subjects from the Alzheimer's disease Neuroimaging Initiative database were adopted for classification between MCI and NC, as well as between AD and NC. Adopting mSCDDL, the classification accuracy achieved 98.5% for AD vs. NC and 82.8% for MCI vs. NC, which were superior to or comparable with the results of some other state-of-the-art approaches as reported in recent multi-modality publications. The mSCDDL procedure was a promising tool in assisting early diseases diagnosis using neuroimaging data. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Wavelet transform and real-time learning method for myoelectric signal in motion discrimination

    Science.gov (United States)

    Liu, Haihua; Chen, Xinhao; Chen, Yaguang

    2005-01-01

    This paper discusses the applicability of the Wavelet transform for analyzing an EMG signal and discriminating motion classes. In many previous works, researchers have dealt with steady EMG and have proposed suitable analyzing methods for the EMG, for example FFT and STFT. Therefore, it is difficult for the previous approaches to discriminate motions from the EMG in the different phases of muscle activity, i.e., pre-activity, in activity, postactivity phases, as well as the period of motion transition from one to another. In this paper, we introduce the Wavelet transform using the Coiflet mother wavelet into our real-time EMG prosthetic hand controller for discriminating motions from steady and unsteady EMG. A preliminary experiment to discriminate three hand motions from four channel EMG in the initial pre-activity and in activity phase is carried out to show the effectiveness of the approach. However, future research efforts are necessary to discriminate more motions much precisely.

  8. An amorphous model for morphological processing in visual comprehension based on naive discriminative learning.

    Science.gov (United States)

    Baayen, R Harald; Milin, Petar; Đurđević, Dusica Filipović; Hendrix, Peter; Marelli, Marco

    2011-07-01

    A 2-layer symbolic network model based on the equilibrium equations of the Rescorla-Wagner model (Danks, 2003) is proposed. The study first presents 2 experiments in Serbian, which reveal for sentential reading the inflectional paradigmatic effects previously observed by Milin, Filipović Đurđević, and Moscoso del Prado Martín (2009) for unprimed lexical decision. The empirical results are successfully modeled without having to assume separate representations for inflections or data structures such as inflectional paradigms. In the next step, the same naive discriminative learning approach is pitted against a wide range of effects documented in the morphological processing literature. Frequency effects for complex words as well as for phrases (Arnon & Snider, 2010) emerge in the model without the presence of whole-word or whole-phrase representations. Family size effects (Moscoso del Prado Martín, Bertram, Häikiö, Schreuder, & Baayen, 2004; Schreuder & Baayen, 1997) emerge in the simulations across simple words, derived words, and compounds, without derived words or compounds being represented as such. It is shown that for pseudo-derived words no special morpho-orthographic segmentation mechanism, as posited by Rastle, Davis, and New (2004), is required. The model also replicates the finding of Plag and Baayen (2009) that, on average, words with more productive affixes elicit longer response latencies; at the same time, it predicts that productive affixes afford faster response latencies for new words. English phrasal paradigmatic effects modulating isolated word reading are reported and modeled, showing that the paradigmatic effects characterizing Serbian case inflection have crosslinguistic scope.

  9. Learning strategy refinement reverses early sensory cortical map expansion but not behavior: Support for a theory of directed cortical substrates of learning and memory.

    Science.gov (United States)

    Elias, Gabriel A; Bieszczad, Kasia M; Weinberger, Norman M

    2015-12-01

    Primary sensory cortical fields develop highly specific associative representational plasticity, notably enlarged area of representation of reinforced signal stimuli within their topographic maps. However, overtraining subjects after they have solved an instrumental task can reduce or eliminate the expansion while the successful behavior remains. As the development of this plasticity depends on the learning strategy used to solve a task, we asked whether the loss of expansion is due to the strategy used during overtraining. Adult male rats were trained in a three-tone auditory discrimination task to bar-press to the CS+ for water reward and refrain from doing so during the CS- tones and silent intertrial intervals; errors were punished by a flashing light and time-out penalty. Groups acquired this task to a criterion within seven training sessions by relying on a strategy that was "bar-press from tone-onset-to-error signal" ("TOTE"). Three groups then received different levels of overtraining: Group ST, none; Group RT, one week; Group OT, three weeks. Post-training mapping of their primary auditory fields (A1) showed that Groups ST and RT had developed significantly expanded representational areas, specifically restricted to the frequency band of the CS+ tone. In contrast, the A1 of Group OT was no different from naïve controls. Analysis of learning strategy revealed this group had shifted strategy to a refinement of TOTE in which they self-terminated bar-presses before making an error ("iTOTE"). Across all animals, the greater the use of iTOTE, the smaller was the representation of the CS+ in A1. Thus, the loss of cortical expansion is attributable to a shift or refinement in strategy. This reversal of expansion was considered in light of a novel theoretical framework (CONCERTO) highlighting four basic principles of brain function that resolve anomalous findings and explaining why even a minor change in strategy would involve concomitant shifts of involved brain

  10. LEARNING STRATEGY REFINEMENT REVERSES EARLY SENSORY CORTICAL MAP EXPANSION BUT NOT BEHAVIOR: SUPPORT FOR A THEORY OF DIRECTED CORTICAL SUBSTRATES OF LEARNING AND MEMORY

    Science.gov (United States)

    Elias, Gabriel A.; Bieszczad, Kasia M.; Weinberger, Norman M.

    2015-01-01

    Primary sensory cortical fields develop highly specific associative representational plasticity, notably enlarged area of representation of reinforced signal stimuli within their topographic maps. However, overtraining subjects after they have solved an instrumental task can reduce or eliminate the expansion while the successful behavior remains. As the development of this plasticity depends on the learning strategy used to solve a task, we asked whether the loss of expansion is due to the strategy used during overtraining. Adult male rats were trained in a three-tone auditory discrimination task to bar-press to the CS+ for water reward and refrain from doing so during the CS− tones and silent intertrial intervals; errors were punished by a flashing light and time-out penalty. Groups acquired this task to a criterion within seven training sessions by relying on a strategy that was “bar-press from tone-onset-to-error signal” (“TOTE”). Three groups then received different levels of overtraining: Group ST, none; Group RT, one week; Group OT, three weeks. Post-training mapping of their primary auditory fields (A1) showed that Groups ST and RT had developed significantly expanded representational areas, specifically restricted to the frequency band of the CS+ tone. In contrast, the A1 of Group OT was no different from naïve controls. Analysis of learning strategy revealed this group had shifted strategy to a refinement of TOTE in which they self-terminated bar-presses before making an error (“iTOTE”). Across all animals, the greater the use of iTOTE, the smaller was the representation of the CS+ in A1. Thus, the loss of cortical expansion is attributable to a shift or refinement in strategy. This reversal of expansion was considered in light of a novel theoretical framework (CONCERTO) highlighting four basic principles of brain function that resolve anomalous findings and explaining why even a minor change in strategy would involve concomitant shifts of

  11. Reversal Learning Task in Children with Autism Spectrum Disorder: A Robot-Based Approach.

    Science.gov (United States)

    Costescu, Cristina A; Vanderborght, Bram; David, Daniel O

    2015-11-01

    Children with autism spectrum disorder (ASD) engage in highly perseverative and inflexible behaviours. Technological tools, such as robots, received increased attention as social reinforces and/or assisting tools for improving the performance of children with ASD. The aim of our study is to investigate the role of the robotic toy Keepon in a cognitive flexibility task performed by children with ASD and typically developing (TD) children. The number of participants included in this study is 81 children: 40 TD children and 41 children with ASD. Each participant had to go through two conditions: robot interaction and human interaction in which they had performed the reversal learning task. Our primary outcomes are the number of errors from acquisition phase and from reversal phase of the task; as secondary outcomes we have measured attentional engagement and positive affect. The results of this study showed that children with ASD are more engaged in the task and they seem to enjoy more the task when interacting with the robot compared with the interaction with the adult. On the other hand their cognitive flexibility performance is, in general, similar in the robot and the human conditions with the exception of the learning phase where the robot can interfere with the performance. Implication for future research and practice are discussed.

  12. Reversal learning in C58 mice: Modeling higher order repetitive behavior.

    Science.gov (United States)

    Whitehouse, Cristina M; Curry-Pochy, Lisa S; Shafer, Robin; Rudy, Joseph; Lewis, Mark H

    2017-08-14

    Restricted, repetitive behaviors are diagnostic for autism and prevalent in other neurodevelopmental disorders. These behaviors cluster as repetitive sensory-motor behaviors and behaviors reflecting resistance to change. The C58 mouse strain is a promising model for these behaviors as it emits high rates of aberrant repetitive sensory-motor behaviors. The purpose of the present study was to extend characterization of the C58 model to resistance to change. This was done by comparing C58 to C57BL/6 mice on a reversal learning task under either a 100% or 80%/20% probabilistic reinforcement schedule. In addition, the effect of environmental enrichment on performance of this task was assessed as this rearing condition markedly reduces repetitive sensory-motor behavior in C58 mice. Little difference was observed between C58 and control mice under a 100% schedule of reinforcement. The 80%/20% probabilistic schedule of reinforcement generated substantial strain differences, however. Importantly, no strain difference was observed in acquisition, but C58 mice were markedly impaired in their ability to reverse their pattern of responding from the previously high density reinforcement side. Environmental enrichment did not impact acquisition under the probabilistic reinforcement schedule, but enriched C58 mice performed significantly better than standard housed C58 mice in reversal learning. Thus, C58 mice exhibit behaviors that reflect both repetitive sensory motor behaviors as well as behavior that reflects resistance to change. Moreover, both clusters of repetitive behavior were attenuated by environmental enrichment. Such findings, along with the reported social deficits in C58 mice, increase the translational value of this mouse model to autism. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Reversal learning in gonadectomized marmosets with and without hormone replacement: are males more sensitive to punishment?

    Science.gov (United States)

    LaClair, Matthew; Lacreuse, Agnès

    2016-05-01

    This study examined sex differences in executive function in middle-aged gonadectomized marmosets (Callithrix jacchus) with or without hormonal replacement. We tested ten castrated male (mean age 5.5 years) marmosets treated with testosterone cypionate (T, n = 5) or vehicle (n = 5) on Reversal Learning, which contributes to cognitive flexibility, and the Delayed Response task, measuring working memory. Their performance was compared to that of 11 ovariectomized females (mean age = 3.7 years) treated with Silastic capsules filled with 17-β estradiol (E2, n = 6) or empty capsules (n = 5), previously tested on the same tasks (Lacreuse et al. in J Neuroendocrinol 26:296-309, 2014. doi: 10.1111/jne.12147). Behavioral observations were conducted daily. Females exhibited more locomotor behaviors than males. Males and females did not differ in the number of trials taken to reach criterion on the reversals, but males had significantly longer response latencies, regardless of hormone replacement. They also had a greater number of refusals than females. Additionally, both control and T-treated males, but not females, had slower responses on incorrect trials, suggesting that males were making errors due to distraction, lack of motivation or uncertainty. Furthermore, although both males and females had slower responding following an incorrect compared to a correct trial, the sex difference in response latencies was disproportionally large following an incorrect trial. No sex difference was found in the Delayed Response task. Overall, slower response latencies in males than females during Reversal Learning, especially during and following an incorrect trial, may reflect greater sensitivity to punishment (omission of reward) and greater performance monitoring in males, compared to females. Because these differences occurred in gonadectomized animals and regardless of hormone replacement, they may be organized early in life.

  14. Change in the relative contributions of habit and working memory facilitates serial reversal learning expertise in rhesus monkeys.

    Science.gov (United States)

    Hassett, Thomas C; Hampton, Robert R

    2017-02-09

    Functionally distinct memory systems likely evolved in response to incompatible demands placed on learning by distinct environmental conditions. Working memory appears adapted, in part, for conditions that change frequently, making rapid acquisition and brief retention of information appropriate. In contrast, habits form gradually over many experiences, adapting organisms to contingencies of reinforcement that are stable over relatively long intervals. Serial reversal learning provides an opportunity to simultaneously examine the processes involved in adapting to rapidly changing and relatively stable contingencies. In serial reversal learning, selecting one of the two simultaneously presented stimuli is positively reinforced, while selection of the other is not. After a preference for the positive stimulus develops, the contingencies of reinforcement reverse. Naïve subjects adapt to such reversals gradually, perseverating in selection of the previously rewarded stimulus. Experts reverse rapidly according to a win-stay, lose-shift response pattern. We assessed whether a change in the relative control of choice by habit and working memory accounts for the development of serial reversal learning expertise. Across three experiments, we applied manipulations intended to attenuate the contribution of working memory but leave the contribution of habit intact. We contrasted performance following long and short intervals in Experiments 1 and 2, and we interposed a competing cognitive load between trials in Experiment 3. These manipulations slowed the acquisition of reversals in expert subjects, but not naïve subjects, indicating that serial reversal learning expertise is facilitated by a shift in the control of choice from passively acquired habit to actively maintained working memory.

  15. Tocotrienol rich fraction reverses age-related deficits in spatial learning and memory in aged rats.

    Science.gov (United States)

    Taridi, Nursiati Mohamad; Abd Rani, Nazirah; Abd Latiff, Azian; Ngah, Wan Zurinah Wan; Mazlan, Musalmah

    2014-09-01

    Little is known about the effect of vitamin E on brain function. Therefore, in this study we evaluated the effect of tocotrienol rich fraction (TRF) on behavioral impairment and oxidative stress in aged rats. Thirty-six male Wistar rats (young: 3-months-old; aged: 21-months-old) were treated with either the control (olive oil) or TRF (200 mg/kg) for 3 months. Behavioral studies were performed using the open field test and Morris water maze (MWM) task. Blood was taken for assessment of DNA damage, plasma malondialdehyde (MDA) and vitamin E, and erythrocyte antioxidant enzyme activity. Brains were also collected to measure vitamin E levels. Results showed that aged rats exhibited reduced exploratory activity, enhanced anxiety and decreased spatial learning and memory compared with young rats. DNA damage and plasma MDA were increased, and vitamin E levels in plasma and brain were reduced in aged rats. Aged rats supplemented with TRF showed a markedly reduced level of anxiety, improved spatial learning and memory, reduced amount and severity of DNA damage, a reduced level of MDA, and increased levels of antioxidant enzyme activity and plasma/brain vitamin E compared with age-matched controls. In conclusion, TRF supplementation reverses spatial learning and memory decline and decreases oxidative stress in aged rats.

  16. Perseveration on a reversal-learning task correlates with rates of self-directed behavior in nonhuman primates.

    Science.gov (United States)

    Judge, Peter G; Evans, David W; Schroepfer, Kara K; Gross, Alyssa C

    2011-09-12

    In humans and several nonhuman animals, repetitive behavior is associated with deficits on executive function tasks involving response inhibition. We tested for this relationship in nonhuman primates by correlating rates of normative behavior to performance on a reversal-learning task in which animals were required to inhibit a previously learned rule. We focused on rates of self-directed behavior (scratch, autogroom, self touch and manipulation) because these responses are known indicators of arousal or anxiety in primates, however, we also examined rates of other categories of behavior (e.g., locomotion). Behavior rates were obtained from 14 animals representing three nonhuman primate species (Macaca silenus, Saimiri sciureus, Cebus apella) living in separate social groups. The same animals were tested on a reversal-learning task in which they were presented with a black and a grey square on a touch screen and were trained to touch the black square. Once animals learned to select the black square, reward contingencies were reversed and animals were rewarded for selecting the grey square. Performance on the reversal-learning task was positively correlated to self-directed behavior in that animals that exhibited higher rates of self-directed behavior required more trials to achieve reversal. Reversal learning was not correlated to rates of any other category of behavior. Results indicate that rates of behavior associated with anxiety and arousal provide an indicator of executive function in nonhuman primates. The relationship suggests continuity between nonhuman primates and humans in the link between executive functioning and repetitive behavior. Copyright © 2011 Elsevier B.V. All rights reserved.

  17. Quantifying explainable discrimination and removing illegal discrimination in automated decision making

    KAUST Repository

    Kamiran, Faisal

    2012-11-18

    Recently, the following discrimination-aware classification problem was introduced. Historical data used for supervised learning may contain discrimination, for instance, with respect to gender. The question addressed by discrimination-aware techniques is, given sensitive attribute, how to train discrimination-free classifiers on such historical data that are discriminative, with respect to the given sensitive attribute. Existing techniques that deal with this problem aim at removing all discrimination and do not take into account that part of the discrimination may be explainable by other attributes. For example, in a job application, the education level of a job candidate could be such an explainable attribute. If the data contain many highly educated male candidates and only few highly educated women, a difference in acceptance rates between woman and man does not necessarily reflect gender discrimination, as it could be explained by the different levels of education. Even though selecting on education level would result in more males being accepted, a difference with respect to such a criterion would not be considered to be undesirable, nor illegal. Current state-of-the-art techniques, however, do not take such gender-neutral explanations into account and tend to overreact and actually start reverse discriminating, as we will show in this paper. Therefore, we introduce and analyze the refined notion of conditional non-discrimination in classifier design. We show that some of the differences in decisions across the sensitive groups can be explainable and are hence tolerable. Therefore, we develop methodology for quantifying the explainable discrimination and algorithmic techniques for removing the illegal discrimination when one or more attributes are considered as explanatory. Experimental evaluation on synthetic and real-world classification datasets demonstrates that the new techniques are superior to the old ones in this new context, as they succeed in

  18. Effects of Repeated Cocaine Exposure on Habit Learning and Reversal by N-Acetylcysteine

    Science.gov (United States)

    Corbit, Laura H; Chieng, Billy C; Balleine, Bernard W

    2014-01-01

    Exposure to drugs of abuse can result in a loss of control over both drug- and nondrug-related actions by accelerating the transition from goal-directed to habitual control, an effect argued to reflect changes in glutamate homeostasis. Here we examined whether exposure to cocaine accelerates habit learning and used in vitro electrophysiology to investigate its effects on measures of synaptic plasticity in the dorsomedial (DMS) and dorsolateral (DLS) striatum, areas critical for actions and habits, respectively. We then administered N-acetylcysteine (NAC) in an attempt to normalize glutamate homeostasis and hence reverse the cellular and behavioral effects of cocaine exposure. Rats received daily injections of cocaine (30 mg/kg) for 6 days and were then trained to lever press for a food reward. We used outcome devaluation and whole-cell patch-clamp electrophysiology to assess the behavioral and cellular effects of cocaine exposure. We then examined the ability of NAC to reverse the effects of cocaine exposure on these measures. Cocaine treatment produced a deficit in goal-directed action, as assessed by outcome devaluation, and increased the frequency of spontaneous and miniature excitatory postsynaptic currents (EPSCs) in the DMS but not in the DLS. Importantly, NAC treatment both normalized EPSC frequency and promoted goal-directed control in cocaine-treated rats. The promotion of goal-directed control has the potential to improve treatment outcomes in human cocaine addicts. PMID:24531561

  19. Observations on auditory learning in amplitude- and frequency-modulation rate discrimination

    DEFF Research Database (Denmark)

    Hoffmann, Pablo F.

    2010-01-01

    Because amplitude- and frequency-modulated sounds can be the basis for the synthesis of many complex sounds, they can be good candidates in the design of training systems aiming at improving the acquisition of perceptual skills that can benefit from information provided via the auditory channel......-training, training, a post-training stages. During training, listeners were divided into two groups; one group trained on amplitude-modulation rate discrimination and the other group trained on frequency-modulation rate discrimination. Results will be discussed in terms of their implications for training...

  20. Very deep learning for ship discrimination in synthetic aperture radar imagery

    CSIR Research Space (South Africa)

    Schwegmann, Colin P

    2016-07-01

    Full Text Available using machine learning. Newer, advanced deep learning techniques offer a unique solution but traditionally require a large dataset to train effectively. Highway Networks allow for very deep networks that can be trained using the smaller datasets typical...

  1. A Comparative Study of Discrimination in Education: The Learning Environment and Behaviours of Students and Teachers in Iran

    Directory of Open Access Journals (Sweden)

    Mozhgan Ghaffarzadeh

    2016-09-01

    Full Text Available It is the learners' right to get an education free from discrimination. Discrimination in education ranges from gender to race, age, social class, financial status, and other characteristics. In this study the focus is on discrimination in education in regard to social class and financial status. The paper describes observations of the school building layout and corresponding activities and behaviours in language education classes. The researcher observed 10 English language classes from different districts during 10 years from 2004 through 2014 and took notes on the activities and behaviours provided in the classroom to identify whether there was any correspondence with educational behaviours. The investigation in this study concluded that the language classes of most of the public (state schools and some semi-private schools included a curriculum based on translation and memorization teaching methods. In these schools, learners exhibited stress and inattention that disturbed their learning. In these classes learners were threatened by laughing or rough criticizing by the teachers. The observation results were analyzed to make comparisons between schools and inform the level of equality in different schools.

  2. An unsupervised learning algorithm: application to the discrimination of seismic events and quarry blasts in the vicinity of Istanbul

    Directory of Open Access Journals (Sweden)

    H. S. Kuyuk

    2011-01-01

    Full Text Available The results of the application of an unsupervised learning (neural network approach comprising a Self Organizing Map (SOM, to distinguish micro-earthquakes from quarry blasts in the vicinity of Istanbul, Turkey, are presented and discussed. The SOM is constructed as a neural classifier and complementary reliability estimator to distinguish seismic events, and was employed for varying map sizes. Input parameters consisting of frequency and time domain data (complexity, spectral ratio, S/P wave amplitude peak ratio and origin time of events extracted from the vertical components of digital seismograms were estimated as discriminants for 179 (1.8 < Md < 3.0 local events. The results show that complexity and amplitude peak ratio parameters of the observed velocity seismogram may suffice for a reliable discrimination, while origin time and spectral ratio were found to be fuzzy and misleading classifiers for this problem. The SOM discussed here achieved a discrimination reliability that could be employed routinely in observatory practice; however, about 6% of all events were classified as ambiguous cases. This approach was developed independently for this particular classification, but it could be applied to different earthquake regions.

  3. Fluid Intelligence and Discriminative Operant Learning of Reinforcement Contingencies in a Fixed Ratio 3 Schedule

    Science.gov (United States)

    Lozano, J. H.; Hernandez, J. M.; Rubio, V. J.; Santacreu, J.

    2011-01-01

    Although intelligence has traditionally been identified as "the ability to learn" (Peterson, 1925), this relationship has been questioned in simple operant learning tasks (Spielberger, 1962). Nevertheless, recent pieces of research have demonstrated a strong and significant correlation between associative learning measures and intelligence…

  4. 局部敏感判别直推学习机%Locality sensitive discriminant transductive learning

    Institute of Scientific and Technical Information of China (English)

    潘俊; 孔繁胜; 王瑞琴

    2012-01-01

    为了充分挖掘样本内在的几何结构和蕴含的判别信息来指导样本数据分类,提出一种局部敏感的判别直推学习方法.该方法将局部敏感辨析(LSDA)的基本原理引入到直推学习中,在直推学习的正则化框架中同时引入有助于分类的样本局部结构信息和判别信息,在判别信息指导下构建了类内图和类间图来刻画类内紧性和类间散性,从而在每个局部邻域中进一步最大化类间样本的间隔.同时,用数学的形式给出了目标函数的解析表达,在几个典型数据集上的实验结果表明,相较传统的基于图的半监督学习算法,该方法能取得更高的分类效果.%A novel approach called locality sensitive discriminant transductive learning (LSD-TL) was developed in order to utilize the underlying geometric structure and the discriminant information to full extent in the process of data classification. Inspired by the basic theories of the locality sensitive discriminant analysis (LSDA), LSD-TL directly incorporates the discriminative information as well as the local geometry of the data space into the regularization framework of transductive learning. LSD-TL constructs the within-class graph and the between-class graph under the guidance of the discriminative information, so that the margins between the data of different classes in each local manifold are maximized. In addition, the analytical solution for the problem was obtained. Experimental results on real world datasets demonstrated that compared with several traditional graph-based semi-supervised algorithms, the new approach improved the classification accuracy.

  5. Challenging the Structural Discrimination of Psychiatric Disabilities: Lessons Learned from the American Disability Community

    Science.gov (United States)

    Corrigan, Patrick W.; Lam, Chow

    2007-01-01

    Stigma is a major barrier to the life opportunities of people with disabilities, including those with psychiatric disabilities. Structural discrimination is stigma that results from social forces that develop over many years to diminish a group's resources and support needed to be successful. Affirmative action is a legal and political remedy to…

  6. Sparse Representations for Image Classification: Learning Discriminative and Reconstructive Non-Parametric Dictionaries

    Science.gov (United States)

    2008-06-01

    December 2006. 7. M. Fritz, B. Leibe, B. Caputo, and B. Schiele . Integrating representative and discriminant models for object category detection. 8... Schiele . Robust object detection with interleaved categorization and segmentation. Int. J. of Computer Vision, 2007 (in press). 18. D. G. Lowe. Distinctive

  7. Challenging the Structural Discrimination of Psychiatric Disabilities: Lessons Learned from the American Disability Community

    Science.gov (United States)

    Corrigan, Patrick W.; Lam, Chow

    2007-01-01

    Stigma is a major barrier to the life opportunities of people with disabilities, including those with psychiatric disabilities. Structural discrimination is stigma that results from social forces that develop over many years to diminish a group's resources and support needed to be successful. Affirmative action is a legal and political remedy to…

  8. SAR Target Recognition via Supervised Discriminative Dictionary Learning and Sparse Representation of the SAR-HOG Feature

    Directory of Open Access Journals (Sweden)

    Shengli Song

    2016-08-01

    Full Text Available Automatic target recognition (ATR in synthetic aperture radar (SAR images plays an important role in both national defense and civil applications. Although many methods have been proposed, SAR ATR is still very challenging due to the complex application environment. Feature extraction and classification are key points in SAR ATR. In this paper, we first design a novel feature, which is a histogram of oriented gradients (HOG-like feature for SAR ATR (called SAR-HOG. Then, we propose a supervised discriminative dictionary learning (SDDL method to learn a discriminative dictionary for SAR ATR and propose a strategy to simplify the optimization problem. Finally, we propose a SAR ATR classifier based on SDDL and sparse representation (called SDDLSR, in which both the reconstruction error and the classification error are considered. Extensive experiments are performed on the MSTAR database under standard operating conditions and extended operating conditions. The experimental results show that SAR-HOG can reliably capture the structures of targets in SAR images, and SDDL can further capture subtle differences among the different classes. By virtue of the SAR-HOG feature and SDDLSR, the proposed method achieves the state-of-the-art performance on MSTAR database. Especially for the extended operating conditions (EOC scenario “Training 17 ∘ —Testing 45 ∘ ”, the proposed method improves remarkably with respect to the previous works.

  9. Age and education adjusted normative data and discriminative validity for Rey's Auditory Verbal Learning Test in the elderly Greek population.

    Science.gov (United States)

    Messinis, Lambros; Nasios, Grigorios; Mougias, Antonios; Politis, Antonis; Zampakis, Petros; Tsiamaki, Eirini; Malefaki, Sonia; Gourzis, Phillipos; Papathanasopoulos, Panagiotis

    2016-01-01

    Rey's Auditory Verbal Learning Test (RAVLT) is a widely used neuropsychological test to assess episodic memory. In the present study we sought to establish normative and discriminative validity data for the RAVLT in the elderly population using previously adapted learning lists for the Greek adult population. We administered the test to 258 cognitively healthy elderly participants, aged 60-89 years, and two patient groups (192 with amnestic mild cognitive impairment, aMCI, and 65 with Alzheimer's disease, AD). From the statistical analyses, we found that age and education contributed significantly to most trials of the RAVLT, whereas the influence of gender was not significant. Younger elderly participants with higher education outperformed the older elderly with lower education levels. Moreover, both clinical groups performed significantly worse on most RAVLT trials and composite measures than matched cognitively healthy controls. Furthermore, the AD group performed more poorly than the aMCI group on most RAVLT variables. Receiver operating characteristic (ROC) analysis was used to examine the utility of the RAVLT trials to discriminate cognitively healthy controls from aMCI and AD patients. Area under the curve (AUC), an index of effect size, showed that most of the RAVLT measures (individual and composite) included in this study adequately differentiated between the performance of healthy elders and aMCI/AD patients. We also provide cutoff scores in discriminating cognitively healthy controls from aMCI and AD patients, based on the sensitivity and specificity of the prescribed scores. Moreover, we present age- and education-specific normative data for individual and composite scores for the Greek adapted RAVLT in elderly subjects aged between 60 and 89 years for use in clinical and research settings.

  10. Learning to Hear by Learning to Speak: The Effect of Articulatory Training on Arab Learners' English Phonemic Discrimination

    Science.gov (United States)

    Linebaugh, Gary; Roche, Thomas

    2013-01-01

    In this paper we explore English pronunciation teaching within an English as an International Language (EIL) framework, arguing that teaching learners how to produce English phonemes can lead to an improvement in their aural ability. English as an Additional Language (EAL) learners often have difficulty discriminating between and producing…

  11. Dopaminergic drug effects during reversal learning depend on anatomical connections between the orbitofrontal cortex and the amygdala.

    Directory of Open Access Journals (Sweden)

    Marieke E. van der Schaaf

    2013-08-01

    Full Text Available Dopamine in the striatum is known to be important for reversal learning. However, the striatum does not act in isolation and reversal learning is also well accepted to depend on the orbitofrontal cortex (OFC and the amygdala. Here we assessed whether dopaminergic drug effects on human striatal BOLD signalling during reversal learning is associated with anatomical connectivity in an orbitofrontal-limbic-striatal network, as measured with diffusion tensor imaging. By using a fibre-based approach, we demonstrate that dopaminergic drug effects on striatal BOLD signal varied as a function of fractional anisotropy (FA in a pathway connecting the OFC with the amygdala. Moreover, our experimental design allowed us to establish that these white-matter dependent drug effects were mediated via D2 receptors. Thus, white matter dependent effects of the D2 receptor agonist bromocriptine on striatal BOLD signal were abolished by co-administration with the D2 receptor antagonist sulpiride. These data provide fundamental insight into the mechanism of action of dopaminergic drug effects during reversal learning. In addition, they may have important clinical implications by suggesting that white matter integrity can help predict dopaminergic drug effects on brain function, ultimately contributing to individual tailoring of dopaminergic drug treatment strategies in psychiatry.

  12. d-cycloserine reverses the detrimental effects of stress on learning in females and enhances retention in males.

    Science.gov (United States)

    Waddell, Jaylyn; Mallimo, Elyse; Shors, Tracey

    2010-01-01

    Exposure to acute, inescapable stress produces a facilitation of subsequent classical eyeblink conditioning in male rats. The same stress exposure produces a profound deficit in classical eyeblink conditioning in females. Activation of N-methyl-d-aspartate receptors (NMDAr) is necessary for the effect of stress on learning in males while the contribution of NMDAr activation to the deficit in learning after stress is unknown. Here, we tested the influence of d-cycloserine (DCS), a positive modulator of the NMDAr, in stressed or unstressed male and female rats. Groups of males and females were exposed to an acute stressful event. One day later, they began training with four sessions of trace eyeblink conditioning. Each day before training, they were injected with DCS (15mg/kg) or saline. Females treated with DCS during training responded similarly to those that were untreated. However, those that were stressed and the next day treated with the drug during training did not express the typical learning deficit, i.e. they learned to time the CR very well. Because the drug was administered well after the stressor, these data indicate that DCS reversed the negative effects of stress on learning in females. In males, the effect of DCS was subtle, resulting in higher asymptotic responding, and enhanced retention in a drug-free retention test. Thus, as shown previously, training in the presence of an NMDA receptor agonist enhances associative learning and memory retention. In addition, it can reverse learning deficits that have already been induced.

  13. Semisupervised learning for a hybrid generative/discriminative classifier based on the maximum entropy principle.

    Science.gov (United States)

    Fujino, Akinori; Ueda, Naonori; Saito, Kazumi

    2008-03-01

    This paper presents a method for designing semi-supervised classifiers trained on labeled and unlabeled samples. We focus on probabilistic semi-supervised classifier design for multi-class and single-labeled classification problems, and propose a hybrid approach that takes advantage of generative and discriminative approaches. In our approach, we first consider a generative model trained by using labeled samples and introduce a bias correction model, where these models belong to the same model family, but have different parameters. Then, we construct a hybrid classifier by combining these models based on the maximum entropy principle. To enable us to apply our hybrid approach to text classification problems, we employed naive Bayes models as the generative and bias correction models. Our experimental results for four text data sets confirmed that the generalization ability of our hybrid classifier was much improved by using a large number of unlabeled samples for training when there were too few labeled samples to obtain good performance. We also confirmed that our hybrid approach significantly outperformed generative and discriminative approaches when the performance of the generative and discriminative approaches was comparable. Moreover, we examined the performance of our hybrid classifier when the labeled and unlabeled data distributions were different.

  14. Discrimination of Brazilian propolis according to the seasoning using chemometrics and machine learning based on UV-Vis scanning data.

    Science.gov (United States)

    Tomazzoli, Maíra Maciel; Pai Neto, Remi Dal; Moresco, Rodolfo; Westphal, Larissa; Zeggio, Amélia Regina Somensi; Specht, Leandro; Costa, Christopher; Rocha, Miguel; Maraschin, Marcelo

    2015-10-21

    Propolis is a chemically complex biomass produced by honeybees (Apis mellifera) from plant resins added of salivary enzymes, beeswax, and pollen. The biological activities described for propolis were also identified for donor plant's resin, but a big challenge for the standardization of the chemical composition and biological effects of propolis remains on a better understanding of the influence of seasonality on the chemical constituents of that raw material. Since propolis quality depends, among other variables, on the local flora which is strongly influenced by (a)biotic factors over the seasons, to unravel the harvest season effect on the propolis' chemical profile is an issue of recognized importance. For that, fast, cheap, and robust analytical techniques seem to be the best choice for large scale quality control processes in the most demanding markets, e.g., human health applications. For that, UV-Visible (UV-Vis) scanning spectrophotometry of hydroalcoholic extracts (HE) of seventy-three propolis samples, collected over the seasons in 2014 (summer, spring, autumn, and winter) and 2015 (summer and autumn) in Southern Brazil was adopted. Further machine learning and chemometrics techniques were applied to the UV-Vis dataset aiming to gain insights as to the seasonality effect on the claimed chemical heterogeneity of propolis samples determined by changes in the flora of the geographic region under study. Descriptive and classification models were built following a chemometric approach, i.e. principal component analysis (PCA) and hierarchical clustering analysis (HCA) supported by scripts written in the R language. The UV-Vis profiles associated with chemometric analysis allowed identifying a typical pattern in propolis samples collected in the summer. Importantly, the discrimination based on PCA could be improved by using the dataset of the fingerprint region of phenolic compounds (λ = 280-400ηm), suggesting that besides the biological activities of those

  15. Generalization Gradients in Human Predictive Learning: Effects of Discrimination Training and within-Subjects Testing

    Science.gov (United States)

    Vervliet, Bram; Iberico, Carlos; Vervoort, Ellen; Baeyens, Frank

    2011-01-01

    Generalization gradients have been investigated widely in animal conditioning experiments, but much less so in human predictive learning tasks. Here, we apply the experimental design of a recent study on conditioned fear generalization in humans (Lissek et al., 2008) to a predictive learning task, and examine the effects of a number of relevant…

  16. Trial-dependent psychometric functions accounting for perceptual learning in 2-AFC discrimination tasks.

    Science.gov (United States)

    Kattner, Florian; Cochrane, Aaron; Green, C Shawn

    2017-09-01

    The majority of theoretical models of learning consider learning to be a continuous function of experience. However, most perceptual learning studies use thresholds estimated by fitting psychometric functions to independent blocks, sometimes then fitting a parametric function to these block-wise estimated thresholds. Critically, such approaches tend to violate the basic principle that learning is continuous through time (e.g., by aggregating trials into large "blocks" for analysis that each assume stationarity, then fitting learning functions to these aggregated blocks). To address this discrepancy between base theory and analysis practice, here we instead propose fitting a parametric function to thresholds from each individual trial. In particular, we implemented a dynamic psychometric function whose parameters were allowed to change continuously with each trial, thus parameterizing nonstationarity. We fit the resulting continuous time parametric model to data from two different perceptual learning tasks. In nearly every case, the quality of the fits derived from the continuous time parametric model outperformed the fits derived from a nonparametric approach wherein separate psychometric functions were fit to blocks of trials. Because such a continuous trial-dependent model of perceptual learning also offers a number of additional advantages (e.g., the ability to extrapolate beyond the observed data; the ability to estimate performance on individual critical trials), we suggest that this technique would be a useful addition to each psychophysicist's analysis toolkit.

  17. Human dorsal striatal activity during choice discriminates reinforcement learning behavior from the gambler's fallacy.

    Science.gov (United States)

    Jessup, Ryan K; O'Doherty, John P

    2011-04-27

    Reinforcement learning theory has generated substantial interest in neurobiology, particularly because of the resemblance between phasic dopamine and reward prediction errors. Actor-critic theories have been adapted to account for the functions of the striatum, with parts of the dorsal striatum equated to the actor. Here, we specifically test whether the human dorsal striatum--as predicted by an actor-critic instantiation--is used on a trial-to-trial basis at the time of choice to choose in accordance with reinforcement learning theory, as opposed to a competing strategy: the gambler's fallacy. Using a partial-brain functional magnetic resonance imaging scanning protocol focused on the striatum and other ventral brain areas, we found that the dorsal striatum is more active when choosing consistent with reinforcement learning compared with the competing strategy. Moreover, an overlapping area of dorsal striatum along with the ventral striatum was found to be correlated with reward prediction errors at the time of outcome, as predicted by the actor-critic framework. These findings suggest that the same region of dorsal striatum involved in learning stimulus-response associations may contribute to the control of behavior during choice, thereby using those learned associations. Intriguingly, neither reinforcement learning nor the gambler's fallacy conformed to the optimal choice strategy on the specific decision-making task we used. Thus, the dorsal striatum may contribute to the control of behavior according to reinforcement learning even when the prescriptions of such an algorithm are suboptimal in terms of maximizing future rewards.

  18. Fullrmc, a rigid body Reverse Monte Carlo modeling package enabled with machine learning and artificial intelligence.

    Science.gov (United States)

    Aoun, Bachir

    2016-05-01

    A new Reverse Monte Carlo (RMC) package "fullrmc" for atomic or rigid body and molecular, amorphous, or crystalline materials is presented. fullrmc main purpose is to provide a fully modular, fast and flexible software, thoroughly documented, complex molecules enabled, written in a modern programming language (python, cython, C and C++ when performance is needed) and complying to modern programming practices. fullrmc approach in solving an atomic or molecular structure is different from existing RMC algorithms and software. In a nutshell, traditional RMC methods and software randomly adjust atom positions until the whole system has the greatest consistency with a set of experimental data. In contrast, fullrmc applies smart moves endorsed with reinforcement machine learning to groups of atoms. While fullrmc allows running traditional RMC modeling, the uniqueness of this approach resides in its ability to customize grouping atoms in any convenient way with no additional programming efforts and to apply smart and more physically meaningful moves to the defined groups of atoms. In addition, fullrmc provides a unique way with almost no additional computational cost to recur a group's selection, allowing the system to go out of local minimas by refining a group's position or exploring through and beyond not allowed positions and energy barriers the unrestricted three dimensional space around a group.

  19. Maternal obesity caused by overnutrition exposure leads to reversal learning deficits and striatal disturbance in rats.

    Science.gov (United States)

    Wu, Ting; Deng, Shining; Li, Wei-Guang; Yu, Yongguo; Li, Fei; Mao, Meng

    2013-01-01

    Maternal obesity caused by overnutrition during pregnancy increases susceptibility to metabolic risks in adulthood, such as obesity, insulin resistance, and type 2 diabetes; however, whether and how it affects the cognitive system associated with the brain remains elusive. Here, we report that pregnant obesity induced by exposure to excessive high fatty or highly palatable food specifically impaired reversal learning, a kind of adaptive behavior, while leaving serum metabolic metrics intact in the offspring of rats, suggesting a much earlier functional and structural defects possibly occurred in the central nervous system than in the metabolic system in the offspring born in unfavorable intrauterine nutritional environment. Mechanically, we found that above mentioned cognitive inflexibility might be associated with significant striatal disturbance including impaired dopamine homeostasis and disrupted leptin signaling in the adult offspring. These collective data add a novel perspective of understanding the adverse postnatal sequelae in central nervous system induced by developmental programming and the related molecular mechanism through which priming of risk for developmental disorders may occur during early life.

  20. Maternal obesity caused by overnutrition exposure leads to reversal learning deficits and striatal disturbance in rats.

    Directory of Open Access Journals (Sweden)

    Ting Wu

    Full Text Available Maternal obesity caused by overnutrition during pregnancy increases susceptibility to metabolic risks in adulthood, such as obesity, insulin resistance, and type 2 diabetes; however, whether and how it affects the cognitive system associated with the brain remains elusive. Here, we report that pregnant obesity induced by exposure to excessive high fatty or highly palatable food specifically impaired reversal learning, a kind of adaptive behavior, while leaving serum metabolic metrics intact in the offspring of rats, suggesting a much earlier functional and structural defects possibly occurred in the central nervous system than in the metabolic system in the offspring born in unfavorable intrauterine nutritional environment. Mechanically, we found that above mentioned cognitive inflexibility might be associated with significant striatal disturbance including impaired dopamine homeostasis and disrupted leptin signaling in the adult offspring. These collective data add a novel perspective of understanding the adverse postnatal sequelae in central nervous system induced by developmental programming and the related molecular mechanism through which priming of risk for developmental disorders may occur during early life.

  1. Perceptual learning of motion direction discrimination with suppressed and unsuppressed MT in humans: an fMRI study.

    Directory of Open Access Journals (Sweden)

    Benjamin Thompson

    Full Text Available The middle temporal area of the extrastriate visual cortex (area MT is integral to motion perception and is thought to play a key role in the perceptual learning of motion tasks. We have previously found, however, that perceptual learning of a motion discrimination task is possible even when the training stimulus contains locally balanced, motion opponent signals that putatively suppress the response of MT. Assuming at least partial suppression of MT, possible explanations for this learning are that 1 training made MT more responsive by reducing motion opponency, 2 MT remained suppressed and alternative visual areas such as V1 enabled learning and/or 3 suppression of MT increased with training, possibly to reduce noise. Here we used fMRI to test these possibilities. We first confirmed that the motion opponent stimulus did indeed suppress the BOLD response within hMT+ compared to an almost identical stimulus without locally balanced motion signals. We then trained participants on motion opponent or non-opponent stimuli. Training with the motion opponent stimulus reduced the BOLD response within hMT+ and greater reductions in BOLD response were correlated with greater amounts of learning. The opposite relationship between BOLD and behaviour was found at V1 for the group trained on the motion-opponent stimulus and at both V1 and hMT+ for the group trained on the non-opponent motion stimulus. As the average response of many cells within MT to motion opponent stimuli is the same as their response to non-directional flickering noise, the reduced activation of hMT+ after training may reflect noise reduction.

  2. Statistical Discriminability Estimation for Pattern Classification Based on Neural Incremental Attribute Learning

    DEFF Research Database (Denmark)

    Wang, Ting; Guan, Sheng-Uei; Puthusserypady, Sadasivan;

    2014-01-01

    estimation. Moreover, a criterion that summarizes all the produced values of AD is employed with a GA (Genetic Algorithm)-based approach to obtain the optimum feature ordering for classification problems based on neural networks by means of IAL. Compared with the feature ordering obtained by other approaches......, the method proposed in this paper exhibits better performance in the final classification results. Such a phenomenon indicates that, (i) the feature discrimination ability should be incrementally estimated in IAL, and (ii) the feature ordering derived by AD and its corresponding approaches are applicable...

  3. Context effects in a temporal discrimination task" further tests of the Scalar Expectancy Theory and Learning-to-Time models.

    Science.gov (United States)

    Arantes, Joana; Machado, Armando

    2008-07-01

    Pigeons were trained on two temporal bisection tasks, which alternated every two sessions. In the first task, they learned to choose a red key after a 1-s signal and a green key after a 4-s signal; in the second task, they learned to choose a blue key after a 4-s signal and a yellow key after a 16-s signal. Then the pigeons were exposed to a series of test trials in order to contrast two timing models, Learning-to-Time (LeT) and Scalar Expectancy Theory (SET). The models made substantially different predictions particularly for the test trials in which the sample duration ranged from 1 s to 16 s and the choice keys were Green and Blue, the keys associated with the same 4-s samples: LeT predicted that preference for Green should increase with sample duration, a context effect, but SET predicted that preference for Green should not vary with sample duration. The results were consistent with LeT. The present study adds to the literature the finding that the context effect occurs even when the two basic discriminations are never combined in the same session.

  4. Learning Discriminative Sparse Models for Source Separation and Mapping of Hyperspectral Imagery

    Science.gov (United States)

    2010-10-01

    in a modification of (4), that allows sparse representations under bounded noise, known as basis pursuit denoising [21], or the Lasso [22]. Its...the atoms of the dictionary. There are several ways for learning these atoms. The K- SVD and Method of Orthogonal Directions (MOD) algorithms [25...Computation, vol. 12, no. 2, pp. 337–365, 2000. [27] M. Elad and M. Aharon, “Image denoising via learned dictionaries and sparse representation,” in

  5. Auditory discrimination predicts linguistic outcome in Italian infants with and without familial risk for language learning impairment.

    Science.gov (United States)

    Cantiani, Chiara; Riva, Valentina; Piazza, Caterina; Bettoni, Roberta; Molteni, Massimo; Choudhury, Naseem; Marino, Cecilia; Benasich, April A

    2016-08-01

    Infants' ability to discriminate between auditory stimuli presented in rapid succession and differing in fundamental frequency (Rapid Auditory Processing [RAP] abilities) has been shown to be anomalous in infants at familial risk for Language Learning Impairment (LLI) and to predict later language outcomes. This study represents the first attempt to investigate RAP in Italian infants at risk for LLI (FH+), examining two critical acoustic features: frequency and duration, both embedded in a rapidly-presented acoustic environment. RAP skills of 24 FH+ and 32 control (FH-) Italian 6-month-old infants were characterized via EEG/ERP using a multi-feature oddball paradigm. Outcome measures of expressive vocabulary were collected at 20 months. Group differences favoring FH- infants were identified: in FH+ infants, the latency of the N2* peak was delayed and the mean amplitude of the positive mismatch response was reduced, primarily for frequency discrimination and within the right hemisphere. Moreover, both EEG measures were correlated with language scores at 20 months. Results indicate that RAP abilities are atypical in Italian infants with a first-degree relative affected by LLI and that this impacts later linguistic skills. These findings provide a compelling cross-linguistic comparison with previous research on American infants, supporting the biological unity hypothesis of LLI. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  6. Externalizing psychopathology and behavioral disinhibition: working memory mediates signal discriminability and reinforcement moderates response bias in approach-avoidance learning.

    Science.gov (United States)

    Endres, Michael J; Rickert, Martin E; Bogg, Tim; Lucas, Jesolyn; Finn, Peter R

    2011-05-01

    Research has suggested that reduced working memory capacity plays a key role in disinhibited patterns of behavior associated with externalizing psychopathology. In this study, participants (N = 365) completed 2 versions of a go/no-go mixed-incentive learning task that differed in the relative frequency of monetary rewards and punishments for correct and incorrect active-approach responses, respectively. Using separate structural equation models for conventional (hit and false alarm rates) and signal detection theory (signal discriminability and response bias) performance indices, distinct roles for working memory capacity and changes in payoff structure were found. Specifically, results showed that (a) working memory capacity mediated the effects of externalizing psychopathology on false alarms and discriminability of go versus no-go signals; (b) these effects were not moderated by the relative frequency of monetary rewards and punishments; (c) the relative frequency of monetary rewards and punishments moderated the effects of externalizing psychopathology on hits and response bias for go versus no-go responses; and (d) these effects were not mediated by working memory capacity. The findings implicate distinct roles for reduced working memory capacity and poorly modulated active approach and passive avoidance in the link between externalizing psychopathology and behavioral disinhibition.

  7. Hemispheric lateralization of memory stages for discriminated avoidance learning in the chick.

    Science.gov (United States)

    Gibbs, Marie E; Andrew, Richard J; Ng, Kim T

    2003-02-17

    Memory formation following the one trial discriminated bead task in the chick falls into three stages (short-term, intermediate and long-term memory) that are defined by susceptibility to different classes of drugs. The stages show sharply timed offsets of sensitivity and loss at specific times after inhibition. Recall of the memory in the chick shows cyclical changes that differ in period between left and right hemispheres, and is marked by a series of brief windows of enhanced recall that recur with periods of about 16 and 25 min in the left and right hemispheres respectively. The timing of these 'retrieval events' corresponds, to a large extent, with the timing of the memory stages seen in the visual discrimination task. Here we examine the effects of left or right hemisphere injection of the main agents (glutamate, ouabain and anisomycin) that have been used to characterize the three stages of memory. We show that memory in the left hemisphere is largely responsible for performance at test and that processes involved in its consolidation generate the phases of memory.

  8. Muscarinic receptor binding increases in anterior thalamus and cingulate cortex during discriminative avoidance learning

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, B.A.; Gabriel, M.; Vogt, L.J.; Poremba, A.; Jensen, E.L.; Kubota, Y.; Kang, E. (Department of Physiology and Pharmacology, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, North Carolina (USA))

    1991-06-01

    Training-induced neuronal activity develops in the mammalian limbic system during discriminative avoidance conditioning. This study explores behaviorally relevant changes in muscarinic ACh receptor binding in 52 rabbits that were trained to one of five stages of conditioned response acquisition. Sixteen naive and 10 animals yoked to criterion performance served as control cases. Upon reaching a particular stage of training, the brains were removed and autoradiographically assayed for 3H-oxotremorine-M binding with 50 nM pirenzepine (OxO-M/PZ) or for 3H-pirenzepine binding in nine limbic thalamic nuclei and cingulate cortex. Specific OxO-M/PZ binding increased in the parvocellular division of the anterodorsal nucleus early in training when the animals were first exposed to pairing of the conditional and unconditional stimuli. Elevated binding in this nucleus was maintained throughout subsequent training. In the parvocellular division of the anteroventral nucleus (AVp), OxO-M/PZ binding progressively increased throughout training, reached a peak at the criterion stage of performance, and returned to control values during extinction sessions. Peak OxO-M/PZ binding in AVp was significantly elevated over that for cases yoked to criterion performance. In the magnocellular division of the anteroventral nucleus (AVm), OxO-M/PZ binding was elevated only during criterion performance of the task, and it was unaltered in any other limbic thalamic nuclei. Specific OxO-M/PZ binding was also elevated in most layers in rostral area 29c when subjects first performed a significant behavioral discrimination. Training-induced alterations in OxO-M/PZ binding in AVp and layer Ia of area 29c were similar and highly correlated.

  9. Distinct linear and non-linear trajectories of reward and punishment reversal learning during development: relevance for dopamine's role in adolescent decision making.

    Science.gov (United States)

    van der Schaaf, Marieke E; Warmerdam, Eveline; Crone, Eveline A; Cools, Roshan

    2011-10-01

    Abnormalities in value-based decision making during adolescence have often been attributed to non-linear, inverted-U shaped development of reward-related processes. This hypothesis is strengthened by functional imaging work revealing an inverted-U shaped relationship between age and reward-related activity in the striatum. However, behavioural studies have mostly reported linear rather than non-linear increases in reward-related performance. In the present study, we investigated the mechanisms underlying the development of reward- and punishment-related processing across four age groups using a reversal learning task previously shown to depend on striatal dopamine. We demonstrate both linear and non-linear age effects on distinct components of reversal learning. Specifically, results revealed a linear shift with age in terms of valence-dependent reversal learning, with children exhibiting better punishment than reward reversal learning, adults exhibiting better reward than punishment reversal learning and adolescents exhibiting an intermediate performance pattern. In addition, we also observed a non-linear, inverted-U shaped relationship between age and valence-independent reversal learning, which was due to aberrant ability of adolescents to update behaviour in response to negative performance feedback. These findings indicate that the (linear or nonlinear) nature of the relationship between age and reward learning depends on the type of reward learning under study.

  10. Investigations on training, recall and reversal learning of a Y-maze by dwarf goats (Capra hircus): the impact of lateralisation.

    Science.gov (United States)

    Langbein, J

    2012-03-01

    We investigated maze learning in dwarf goats (Capra hircus) and the impact of lateralisation on learning. Lateralisation refers to the collection of phenomena in which external stimuli are perceived and processed differentially on the two sides of the brain and/or certain behaviours are preferentially performed by one side of the body. We trained 29 dwarf goats in a Y-maze, directing them to the opposite alley from that chosen in a free pre-run. In total, 13 goats were trained to the left alley (L-goats) and 16 goats to the right alley (R-goats). Recall of the trained alley was tested three months later. We then analysed reversal learning across 10 reversals. During training, the direction of the alley had an impact on learning. The number of runs required to reach the learning criterion was significantly lower in the L- than the R-goats. The goats recalled the trained alley three months later, with no difference between the L- and the R-goats. During the reversal learning, the reversal only tended to impact learning performance, whereas the directions of the new and the initially trained alley did not. Goats did not adopt a general rule with which to master the maze (e.g., win-stay/lose-shift) across the 10 reversals. Our results indicate a right hemisphere bias in the processing of visuospatial cues in the maze during initial training; however, no such impact was detected during reversal learning.

  11. Closing the gap between frugal and reverse innovation : Lessons learned from the case of the Tata Nano

    OpenAIRE

    Aschmoneit, Martin; Janevska, Dijana

    2013-01-01

    Abstract Title: Closing the gap between frugal and reverse innovation – Lessons learned from the case of the Tata Nano Authors: Martin Aschmoneit () Dijana Janevska () Supervisor: Malin Tillmar Date: May 27, 2013 Background: Emerging markets are growing and have become increasingly important for the global economy, while the growth of developed markets has slowed down. Emerging economies are the home of a new type of innovation that can help...

  12. Combining Generative and Discriminative Representation Learning for Lung CT Analysis With Convolutional Restricted Boltzmann Machines

    NARCIS (Netherlands)

    G. van Tulder (Gijs); M. de Bruijne (Marleen)

    2016-01-01

    textabstractThe choice of features greatly influences the performance of a tissue classification system. Despite this, many systems are built with standard, predefined filter banks that are not optimized for that particular application. Representation learning methods such as restricted Boltzmann ma

  13. DeepTrack: Learning Discriminative Feature Representations Online for Robust Visual Tracking.

    Science.gov (United States)

    Hanxi Li; Yi Li; Porikli, Fatih

    2016-04-01

    Deep neural networks, albeit their great success on feature learning in various computer vision tasks, are usually considered as impractical for online visual tracking, because they require very long training time and a large number of training samples. In this paper, we present an efficient and very robust tracking algorithm using a single convolutional neural network (CNN) for learning effective feature representations of the target object in a purely online manner. Our contributions are multifold. First, we introduce a novel truncated structural loss function that maintains as many training samples as possible and reduces the risk of tracking error accumulation. Second, we enhance the ordinary stochastic gradient descent approach in CNN training with a robust sample selection mechanism. The sampling mechanism randomly generates positive and negative samples from different temporal distributions, which are generated by taking the temporal relations and label noise into account. Finally, a lazy yet effective updating scheme is designed for CNN training. Equipped with this novel updating algorithm, the CNN model is robust to some long-existing difficulties in visual tracking, such as occlusion or incorrect detections, without loss of the effective adaption for significant appearance changes. In the experiment, our CNN tracker outperforms all compared state-of-the-art methods on two recently proposed benchmarks, which in total involve over 60 video sequences. The remarkable performance improvement over the existing trackers illustrates the superiority of the feature representations, which are learned purely online via the proposed deep learning framework.

  14. Different Parameters Support Generalization and Discrimination Learning in "Drosophila" at the Flight Simulator

    Science.gov (United States)

    Brembs, Bjorn; de Ibarra, Natalie Hempel

    2006-01-01

    We have used a genetically tractable model system, the fruit fly "Drosophila melanogaster" to study the interdependence between sensory processing and associative processing on learning performance. We investigated the influence of variations in the physical and predictive properties of color stimuli in several different operant-conditioning…

  15. Discriminative kernel feature extraction and learning for object recognition and detection

    DEFF Research Database (Denmark)

    Pan, Hong; Olsen, Søren Ingvor; Zhu, Yaping

    2015-01-01

    Feature extraction and learning is critical for object recognition and detection. By embedding context cue of image attributes into the kernel descriptors, we propose a set of novel kernel descriptors called context kernel descriptors (CKD). The motivation of CKD is to use the spatial consistency...

  16. Combining Generative and Discriminative Representation Learning for Lung CT Analysis With Convolutional Restricted Boltzmann Machines

    NARCIS (Netherlands)

    G. van Tulder (Gijs); M. de Bruijne (Marleen)

    2016-01-01

    textabstractThe choice of features greatly influences the performance of a tissue classification system. Despite this, many systems are built with standard, predefined filter banks that are not optimized for that particular application. Representation learning methods such as restricted Boltzmann

  17. English- and Mandarin-Learning Infants' Discrimination of Actions and Objects in Dynamic Events

    Science.gov (United States)

    Chen, Jie; Tardif, Twila; Pulverman, Rachel; Casasola, Marianella; Zhu, Liqi; Zheng, Xiaobei; Meng, Xiangzhi

    2015-01-01

    The present studies examined the role of linguistic experience in directing English and Mandarin learners' attention to aspects of a visual scene. Specifically, they asked whether young language learners in these 2 cultures attend to differential aspects of a word-learning situation. Two groups of English and Mandarin learners, 6-8-month-olds (n =…

  18. Brain Responses Reveal That Infants' Face Discrimination Is Guided by Statistical Learning from Distributional Information

    Science.gov (United States)

    Altvater-Mackensen, Nicole; Jessen, Sarah; Grossmann, Tobias

    2017-01-01

    Infants' perception of faces becomes attuned to the environment during the first year of life. However, the mechanisms that underpin perceptual narrowing for faces are only poorly understood. Considering the developmental similarities seen in perceptual narrowing for faces and speech and the role that statistical learning has been shown to play…

  19. Online feedback enhances early consolidation of motor sequence learning and reverses recall deficit from transcranial stimulation of motor cortex.

    Science.gov (United States)

    Wilkinson, Leonora; Steel, Adam; Mooshagian, Eric; Zimmermann, Trelawny; Keisler, Aysha; Lewis, Jeffrey D; Wassermann, Eric M

    2015-10-01

    Feedback and monetary reward can enhance motor skill learning, suggesting reward system involvement. Continuous theta burst (cTBS) transcranial magnetic stimulation (TMS) of the primary motor area (M1) disrupts processing, reduces excitability and impairs motor learning. To see whether feedback and reward can overcome the learning impairment associated with M1 cTBS, we delivered real or sham stimulation to two groups of participants before they performed a motor sequence learning task with and without feedback. Participants were trained on two intermixed sequences, one occurring 85% of the time (the "probable" sequence) and the other 15% of the time (the "improbable" sequence). We measured sequence learning as the difference in reaction time (RT) and error rate between probable and improbable trials (RT and error difference scores). Participants were also tested for sequence recall with the same indices of learning 60 min after cTBS. Real stimulation impaired initial sequence learning and sequence knowledge recall as measured by error difference scores and impaired sequence knowledge recall as measured by RT difference score. Relative to non-feedback learning, the introduction of feedback during sequence learning improved subsequent sequence knowledge recall indexed by RT difference score, in both real and sham stimulation groups and feedback reversed the RT difference score based sequence knowledge recall impairment from real cTBS that we observed in the non-feedback learning condition. Only the real cTBS group in the non-feedback condition showed no evidence of explicit sequence knowledge when tested at the end of the study. Feedback improves recall of implicit and explicit motor sequence knowledge and can protect sequence knowledge against the effect of M1 inhibition. Adding feedback and monetary reward/punishment to motor skill learning may help overcome retention impairments or accelerate training in clinical and other settings. Published by Elsevier Ltd.

  20. Jordan-3: measuring visual reversals in children as symptoms of learning disability and attention-deficit/hyperactivity disorder.

    Science.gov (United States)

    Jordan, Brian T; Martin, Nancy; Austin, J Sue

    2012-12-01

    The purpose of this research was to establish new norms for the Jordan-3 for children ages 5 to 18 years. The research also investigated the frequency of visual reversals in children previously identified as having reading disability, attention-deficit/hyperactivity disorder, and broader learning disabilities. Participants were regular education students, ages 5 through 18 years, and special education students previously diagnosed with attention-deficit/hyperactivity disorder, reading disability, or broader learning disability. Jordan-3 Accuracy and Error raw scores were compared to assess if there was a significant difference between the two groups. Mean Accuracy and Error scores were compared for males and females. Children with learning disability and attention-deficit/hyperactivity disorder had higher reversals when compared to regular education children, which lends continued support to the Jordan-3 as a valid and reliable measure of visual reversals in children and adolescents. This study illustrates the utility of the Jordan-3 when assessing children who may require remediation to reach their academic potential.

  1. Physiological expression of olfactory discrimination rule learning balances whole-population modulation and circuit stability in the piriform cortex network.

    Science.gov (United States)

    Jammal, Luna; Whalley, Ben; Ghosh, Sourav; Lamrecht, Raphael; Barkai, Edi

    2016-07-01

    Once trained, rats are able to execute particularly difficult olfactory discrimination tasks with exceptional accuracy. Such skill acquisition, termed "rule learning", is accompanied by a series of long-lasting modifications to three cellular properties which modulate pyramidal neuron activity in piriform cortex; intrinsic excitability, synaptic excitation, and synaptic inhibition. Here, we explore how these changes, which are seemingly contradictory at the single-cell level in terms of their effect on neuronal excitation, are manifested within the piriform cortical neuronal network to store the memory of the rule, while maintaining network stability. To this end, we monitored network activity via multisite extracellular recordings of field postsynaptic potentials (fPSPS) and with single-cell recordings of miniature inhibitory and excitatory synaptic events in piriform cortex slices. We show that although 5 days after rule learning the cortical network maintains its basic activity patterns, synaptic connectivity is strengthened specifically between spatially proximal cells. Moreover, while the enhancement of inhibitory and excitatory synaptic connectivity is nearly identical, strengthening of synaptic inhibition is equally distributed between neurons while synaptic excitation is particularly strengthened within a specific subgroup of cells. We suggest that memory for the acquired rule is stored mainly by strengthening excitatory synaptic connection between close pyramidal neurons and runaway synaptic activity arising from this change is prevented by a nonspecific enhancement of synaptic inhibition.

  2. Ineffectiveness of Reverse Wording of Questionnaire Items : Let's Learn from Cows in the Rain

    NARCIS (Netherlands)

    van Sonderen, Eric; Sanderman, Robbert; Coyne, James C.

    2013-01-01

    Objective: We examined the effectiveness of reverse worded items as a means of reducing or preventing response bias. We first distinguished between several types of response bias that are often confused in literature. We next developed arguments why reversing items is probably never a good way to ad

  3. Solving petrological problems through machine learning: the study case of tectonic discrimination using geochemical and isotopic data

    Science.gov (United States)

    Petrelli, Maurizio; Perugini, Diego

    2016-10-01

    Machine-learning methods are evaluated to study the intriguing and debated topic of discrimination among different tectonic environments using geochemical and isotopic data. Volcanic rocks characterized by a whole geochemical signature of major elements (SiO2, TiO2, Al2O3, Fe2O3T, CaO, MgO, Na2O, K2O), selected trace elements (Sr, Ba, Rb, Zr, Nb, La, Ce, Nd, Hf, Sm, Gd, Y, Yb, Lu, Ta, Th) and isotopes (206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb, 87Sr/86Sr and 143Nd/144Nd) have been extracted from open-access and comprehensive petrological databases (i.e., PetDB and GEOROC). The obtained dataset has been analyzed using support vector machines, a set of supervised machine-learning methods, which are considered particularly powerful in classification problems. Results from the application of the machine-learning methods show that the combined use of major, trace elements and isotopes allows associating the geochemical composition of rocks to the relative tectonic setting with high classification scores (93 %, on average). The lowest scores are recorded from volcanic rocks deriving from back-arc basins (65 %). All the other tectonic settings display higher classification scores, with oceanic islands reaching values up to 99 %. Results of this study could have a significant impact in other petrological studies potentially opening new perspectives for petrologists and geochemists. Other examples of applications include the development of more robust geothermometers and geobarometers and the recognition of volcanic sources for tephra layers in tephro-chronological studies.

  4. Genetic Discrimination

    Science.gov (United States)

    ... in Genetics Archive Regulation of Genetic Tests Genetic Discrimination Overview Many Americans fear that participating in research ... I) and employment (Title II). Read more Genetic Discrimination and Other Laws Genetic Discrimination and Other Laws ...

  5. A Comparative Study of Discrimination in Education: The Learning Environment and Behaviours of Students and Teachers in Iran

    Science.gov (United States)

    Ghaffarzadeh, Mozhgan

    2016-01-01

    It is the learners' right to get an education free from discrimination. Discrimination in education ranges from gender to race, age, social class, financial status, and other characteristics. In this study the focus is on discrimination in education in regard to social class and financial status. The paper describes observations of the school…

  6. Discriminative Transfer Subspace Learning via Low-Rank and Sparse Representation.

    Science.gov (United States)

    Xu, Yong; Fang, Xiaozhao; Wu, Jian; Li, Xuelong; Zhang, David

    2016-02-01

    In this paper, we address the problem of unsupervised domain transfer learning in which no labels are available in the target domain. We use a transformation matrix to transfer both the source and target data to a common subspace, where each target sample can be represented by a combination of source samples such that the samples from different domains can be well interlaced. In this way, the discrepancy of the source and target domains is reduced. By imposing joint low-rank and sparse constraints on the reconstruction coefficient matrix, the global and local structures of data can be preserved. To enlarge the margins between different classes as much as possible and provide more freedom to diminish the discrepancy, a flexible linear classifier (projection) is obtained by learning a non-negative label relaxation matrix that allows the strict binary label matrix to relax into a slack variable matrix. Our method can avoid a potentially negative transfer by using a sparse matrix to model the noise and, thus, is more robust to different types of noise. We formulate our problem as a constrained low-rankness and sparsity minimization problem and solve it by the inexact augmented Lagrange multiplier method. Extensive experiments on various visual domain adaptation tasks show the superiority of the proposed method over the state-of-the art methods. The MATLAB code of our method will be publicly available at http://www.yongxu.org/lunwen.html.

  7. Learning discriminative features from RGB-D images for gender and ethnicity identification

    Science.gov (United States)

    Azzakhnini, Safaa; Ballihi, Lahoucine; Aboutajdine, Driss

    2016-11-01

    The development of sophisticated sensor technologies gave rise to an interesting variety of data. With the appearance of affordable devices, such as the Microsoft Kinect, depth-maps and three-dimensional data became easily accessible. This attracted many computer vision researchers seeking to exploit this information in classification and recognition tasks. In this work, the problem of face classification in the context of RGB images and depth information (RGB-D images) is addressed. The purpose of this paper is to study and compare some popular techniques for gender recognition and ethnicity classification to understand how much depth data can improve the quality of recognition. Furthermore, we investigate which combination of face descriptors, feature selection methods, and learning techniques is best suited to better exploit RGB-D images. The experimental results show that depth data improve the recognition accuracy for gender and ethnicity classification applications in many use cases.

  8. Learning discriminative patterns for self-paced EEG-based motor imagery detection

    Directory of Open Access Journals (Sweden)

    Haihong eZhang

    2012-02-01

    Full Text Available Detecting motor imagery activities versus non-control in brain signals is the basis of self-paced brain-computer interfaces (BCIs, but also poses a considerable challenge to signal processing due to the complex and non-stationary characteristics of motor imagery as well as non-control. This paper presents a self-paced BCI based on a robust learning mechanism that extracts and selects spatio-spectral features for differentiating multiple EEG classes. It also employs a nonlinear regression and post-processing technique for predicting the time-series of class labels from the spatio-spectral features. The method was validated in the {BCI Competition IV} on {Dataset I} where it produced the lowest prediction error of class labels continuously. This report also presents and discusses analysis of the method using the competition data set.

  9. Ineffectiveness of reverse wording of questionnaire items: let's learn from cows in the rain.

    Directory of Open Access Journals (Sweden)

    Eric van Sonderen

    Full Text Available OBJECTIVE: We examined the effectiveness of reverse worded items as a means of reducing or preventing response bias. We first distinguished between several types of response bias that are often confused in literature. We next developed arguments why reversing items is probably never a good way to address response bias. We proposed testing whether reverse wording affects response bias with item-level data from the Multidimensional Fatigue Inventory (MFI-20, an instrument that contains reversed worded items. METHODS: With data from 700 respondents, we compared scores on items that were similar with respect either to content or to direction of wording. Psychometric properties of sets of these items worded in the same direction were compared with sets consisting of both straightforward and reversed worded items. RESULTS: We did not find evidence that ten reverse-worded items prevented response bias. Instead, the data suggest scores were contaminated by respondent inattention and confusion. CONCLUSIONS: Using twenty items, balanced for scoring direction, to assess fatigue did not prevent respondents from inattentive or acquiescent answering. Rather, fewer mistakes are made with a 10-item instrument with items posed in the same direction. Such a format is preferable for both epidemiological and clinical studies.

  10. Physicochemical descriptors to discriminate protein-protein interactions in permanent and transient complexes selected by means of machine learning algorithms.

    Science.gov (United States)

    Block, Peter; Paern, Juri; Hüllermeier, Eyke; Sanschagrin, Paul; Sotriffer, Christoph A; Klebe, Gerhard

    2006-11-15

    Analyzing protein-protein interactions at the atomic level is critical for our understanding of the principles governing the interactions involved in protein-protein recognition. For this purpose, descriptors explaining the nature of different protein-protein complexes are desirable. In this work, the authors introduced Epic Protein Interface Classification as a framework handling the preparation, processing, and analysis of protein-protein complexes for classification with machine learning algorithms. We applied four different machine learning algorithms: Support Vector Machines, C4.5 Decision Trees, K Nearest Neighbors, and Naïve Bayes algorithm in combination with three feature selection methods, Filter (Relief F), Wrapper, and Genetic Algorithms, to extract discriminating features from the protein-protein complexes. To compare protein-protein complexes to each other, the authors represented the physicochemical characteristics of their interfaces in four different ways, using two different atomic contact vectors, DrugScore pair potential vectors and SFCscore descriptor vectors. We classified two different datasets: (A) 172 protein-protein complexes comprising 96 monomers, forming contacts enforced by the crystallographic packing environment (crystal contacts), and 76 biologically functional homodimer complexes; (B) 345 protein-protein complexes containing 147 permanent complexes and 198 transient complexes. We were able to classify up to 94.8% of the packing enforced/functional and up to 93.6% of the permanent/transient complexes correctly. Furthermore, we were able to extract relevant features from the different protein-protein complexes and introduce an approach for scoring the importance of the extracted features. (c) 2006 Wiley-Liss, Inc.

  11. PKMzeta inhibition reverses learning-induced increases in hippocampal synaptic strength and memory during trace eyeblink conditioning.

    Directory of Open Access Journals (Sweden)

    Noelia Madroñal

    Full Text Available A leading candidate in the process of memory formation is hippocampal long-term potentiation (LTP, a persistent enhancement in synaptic strength evoked by the repetitive activation of excitatory synapses, either by experimental high-frequency stimulation (HFS or, as recently shown, during actual learning. But are the molecular mechanisms for maintaining synaptic potentiation induced by HFS and by experience the same? Protein kinase Mzeta (PKMzeta, an autonomously active atypical protein kinase C isoform, plays a key role in the maintenance of LTP induced by tetanic stimulation and the storage of long-term memory. To test whether the persistent action of PKMzeta is necessary for the maintenance of synaptic potentiation induced after learning, the effects of ZIP (zeta inhibitory peptide, a PKMzeta inhibitor, on eyeblink-conditioned mice were studied. PKMzeta inhibition in the hippocampus disrupted both the correct retrieval of conditioned responses (CRs and the experience-dependent persistent increase in synaptic strength observed at CA3-CA1 synapses. In addition, the effects of ZIP on the same associative test were examined when tetanic LTP was induced at the hippocampal CA3-CA1 synapse before conditioning. In this case, PKMzeta inhibition both reversed tetanic LTP and prevented the expected LTP-mediated deleterious effects on eyeblink conditioning. Thus, PKMzeta inhibition in the CA1 area is able to reverse both the expression of trace eyeblink conditioned memories and the underlying changes in CA3-CA1 synaptic strength, as well as the anterograde effects of LTP on associative learning.

  12. Hand Gesture recognition and classification by Discriminant and Principal Component Analysis using Machine Learning techniques

    Directory of Open Access Journals (Sweden)

    Sauvik Das Gupta

    2012-12-01

    Full Text Available This paper deals with the recognition of different hand gestures through machine learning approaches and principal component analysis. A Bio-Medical signal amplifier is built after doing a software simulation with the help of NI Multisim. At first a couple of surface electrodes are used to obtain the Electro-Myo-Gram (EMG signals from the hands. These signals from the surface electrodes have to be amplified with the help of the Bio-Medical Signal amplifier. The Bio-Medical Signal amplifier used is basically an Instrumentation amplifier made with the help of IC AD 620.The output from the Instrumentation amplifier is then filtered with the help of a suitable Band-Pass Filter. The output from the Band Pass filter is then fed to an Analog to Digital Converter (ADC which in this case is the NI USB 6008.The data from the ADC is then fed into a suitable algorithm which helps in recognition of the different hand gestures. The algorithm analysis is done in MATLAB. The results shown in this paper show a close to One-hundred per cent (100% classification result for three given hand gestures.

  13. Glabridin as a major active isoflavan from Glycyrrhiza glabra (licorice) reverses learning and memory deficits in diabetic rats.

    Science.gov (United States)

    Hasanein, Parisa

    2011-06-01

    Cognitive impairment occurs in diabetes mellitus. Glabridin as a major active flavonoids in Glycyrrhiza glabra (licorice) improves learning and memory in mice. In the present study, we investigated the effect of chronic treatment with glabridin (5, 25 and 50 mg/kg, p.o.) on cognitive function in control and streptozotocin (STZ)-induced diabetic rats.Animals were divided into untreated control, glabridin-treated control (5, 25 and 50 mg/kg), untreated diabetic and glabridin treated diabetic (5, 25 and 50 mg/kg) groups. Treatments were begun at the onset of hyperglycemia. Passive avoidance learning (PAL) and memory was assessed 30 days later. Diabetes caused cognition deficits in the PAL and memory paradigm. While oral glabridin administration (25 and 50 mg/kg) improved learning and memory in non-diabetic rats, it reversed learning and memory deficits of diabetic rats. Low dose glabridin (5 mg/kg) did not alter cognitive function in non-diabetic and diabetic groups. Glabridin treatment partially improved the reduced body weight and hyperglycemia of diabetic rats although the differences were not significant. The combination of antioxidant, neuroprotective and anticholinesterase properties of glabridin may all be responsible for the observed effects. These results show that glabridin prevented the deleterious effects of diabetes on learning and memory in rats. Further studies are warranted for clinical use of glabridin in the management of demented diabetic patients.

  14. Modeling psychotic and cognitive symptoms of affective disorders: Disrupted latent inhibition and reversal learning deficits in highly stress reactive mice.

    Science.gov (United States)

    Knapman, A; Heinzmann, J-M; Holsboer, F; Landgraf, R; Touma, C

    2010-09-01

    Increased stress reactivity has repeatedly been reported in patients suffering from psychiatric diseases including schizophrenia and major depression. These disorders also have other symptoms in common, such as cognitive deficits and psychotic-like behavior. We have therefore investigated if increased stress reactivity is associated with these phenotypic endpoints in an animal model of affective disorders. The stress reactivity mouse model used in this study consists of three CD-1-derived mouse lines, that have been selectively bred for high (HR), intermediate (IR) or low (LR) stress reactivity. Male mice from these three breeding lines were subjected to a reversal learning task and latent inhibition (Li) was assessed using a conditioned taste aversion paradigm. Furthermore, as the dopaminergic system is involved in both Li and reversal learning, the dopamine 1 receptor (D1R), dopamine 2 receptor (D2R) and dopamine transporter (DAT) mRNA expression levels were assessed in relevant brain areas of these animals. The results demonstrate that HR mice show perseveration in the reversal learning task and have disrupted Li. Furthermore, compared to LR mice, HR mice have decreased D2R mRNA levels in the ventral tegmental area, as well as decreased D1R mRNA levels in the cingulate cortex, and an increased expression of D2R mRNA in the nucleus accumbens. Taken together, these results demonstrate that the HR mice display cognitive deficits associated with psychotic-like behavior, similar to those observed in patients suffering from schizophrenia and major depression and could be utilized in the search for better treatment strategies for these symptoms of psychiatric disorders.

  15. In a daily time-place learning task, time is only used as a discriminative stimulus if each daily session is associated with a distinct spatial location.

    Science.gov (United States)

    Deibel, Scott H; Ingram, Matthew L; Lehr, Andrew B; Martin, Hiliary C; Skinner, Darlene M; Martin, Gerard M; Hughes, Isaac M W; Thorpe, Christina M

    2014-09-01

    It is difficult for rats to acquire daily time-place (TP) learning tasks. One theory suggests that rats do not use time of day as a stimulus signaling a specific response. In the present study, we tested rats' ability to use time of day as a discriminative stimulus. A fixed-interval procedure was used in which one lever provided reinforcement on a FI-5-s schedule in morning sessions, and the same lever provided reinforcement on a FI-30-s schedule in afternoon sessions. Because only one place was used in this paradigm, the rats could only use time of day to acquire the task. Mean responses during the first 5 s of the first trial in each session indicated that the rats did not discriminate between the two sessions. In Phase II, a different lever location was used for each of the two daily sessions, which meant that both spatial and temporal information could be used to acquire the task. The rats readily acquired the task in this phase, and probe trials indicated that the rats were using a combination of spatial and temporal information to discriminate between the two different trial types. When the spatial cue was removed in Phase III, rats no longer discriminated the two sessions, suggesting that time can only be used as a discriminative stimulus when each daily session is associated with a distinct spatial location.

  16. Automated discrimination of dicentric and monocentric chromosomes by machine learning-based image processing.

    Science.gov (United States)

    Li, Yanxin; Knoll, Joan H; Wilkins, Ruth C; Flegal, Farrah N; Rogan, Peter K

    2016-05-01

    Dose from radiation exposure can be estimated from dicentric chromosome (DC) frequencies in metaphase cells of peripheral blood lymphocytes. We automated DC detection by extracting features in Giemsa-stained metaphase chromosome images and classifying objects by machine learning (ML). DC detection involves (i) intensity thresholded segmentation of metaphase objects, (ii) chromosome separation by watershed transformation and elimination of inseparable chromosome clusters, fragments and staining debris using a morphological decision tree filter, (iii) determination of chromosome width and centreline, (iv) derivation of centromere candidates, and (v) distinction of DCs from monocentric chromosomes (MC) by ML. Centromere candidates are inferred from 14 image features input to a Support Vector Machine (SVM). Sixteen features derived from these candidates are then supplied to a Boosting classifier and a second SVM which determines whether a chromosome is either a DC or MC. The SVM was trained with 292 DCs and 3135 MCs, and then tested with cells exposed to either low (1 Gy) or high (2-4 Gy) radiation dose. Results were then compared with those of 3 experts. True positive rates (TPR) and positive predictive values (PPV) were determined for the tuning parameter, σ. At larger σ, PPV decreases and TPR increases. At high dose, for σ = 1.3, TPR = 0.52 and PPV = 0.83, while at σ = 1.6, the TPR = 0.65 and PPV = 0.72. At low dose and σ = 1.3, TPR = 0.67 and PPV = 0.26. The algorithm differentiates DCs from MCs, overlapped chromosomes and other objects with acceptable accuracy over a wide range of radiation exposures.

  17. Machine learning of global phosphoproteomic profiles enables discrimination of direct versus indirect kinase substrates.

    Science.gov (United States)

    Kanshin, Evgeny; Giguere, Sebastien; Cheng, Jing; Tyers, Michael D; Thibault, Pierre

    2017-03-06

    Mass spectrometry allows quantification of tens of thousands of phosphorylation sites from minute amounts of cellular material. Despite this wealth of information, our understanding of phosphorylation-based signaling is limited, in part because it is not possible to deconvolute substrate phosphorylation that is directly mediated by a particular kinase versus phosphorylation that is mediated by downstream kinases. Here, we describe a framework for assignment of direct in-vivo kinase substrates using a combination of selective chemical inhibition, quantitative phosphoproteomics, and machine learning techniques. Our workflow allows classification of phosphorylation events following inhibition of an analog-sensitive kinase into kinase-independent effects of the inhibitor, direct effects on cognate substrates and indirect effects mediated by downstream kinases or phosphatases. We applied this method to identify many direct targets of Cdc28 and Snf1 kinases in the budding yeast S. cerevisiae. Global phosphoproteome analysis of acute time-series demonstrated that dephosphorylation of direct kinase substrates occurs more rapidly compared to indirect substrates, both after inhibitor treatment and under a physiological nutrient shift in wild-type cells. Mutagenesis experiments revealed a high proportion of functionally relevant phosphorylation sites on Snf1 targets. For example, Snf1 itself was inhibited through autophosphorylation on S391 and new phosphosites were discovered that modulate the activity of the Reg1 regulatory subunit of the Glc7 phosphatase and the Gal83 β-subunit of SNF1 complex. This methodology applies to any kinase for which a functional analog sensitive version can be constructed to facilitate the dissection of the global phosphorylation network.

  18. Housing condition-related changes involved in reversal learning and its c-Fos associated activity in the prefrontal cortex.

    Science.gov (United States)

    Sampedro-Piquero, P; Zancada-Menendez, C; Begega, A

    2015-10-29

    Our study examined how different housing conditions modulated the acquisition of a spatial reference memory task and also, a reversal task in the 4-radial arm water maze (4-RAWM). The animals were randomly assigned to standard or enriched cages, and, as a type of complementary stimulation along with the environmental enrichment (EE), a group of rats also ran 15 min/day in a Rotarod. Elevated-zero maze results allowed us to discard that our exercise training increased anxiety-related behaviors. 4-RAWM results revealed that the non-enriched group had a worse performance during the acquisition and also, during the first trial of each session with respect to the enriched groups. Regarding the reversal task, this group made more perseverative errors in the previous platform position. Interestingly, we hardly found differences between the two enriched groups (with and without exercise). We also analyzed how the reversal learning, depending on the previous housing condition, modulated the expression of c-Fos-positive nuclei in different subdivisions of the medial prefrontal cortex (cingulate (Cg), prelimbic (PL) and infralimbic (IL) cortices) and in the orbitofrontal (OF) cortex. The enriched groups had higher c-Fos expression in the Cg and OF cortices and lower in the IL cortex respect to the non-enriched animals. In the PL cortex, we did not find significant differences between the groups that performed the reversal task. Therefore, our short EE protocol improved the performance in a spatial memory and a reversal task, whereas the exercise training, combined with the EE, did not produce a greater benefit. This better performance seemed to be related with the specific pattern of c-Fos expression in brain regions involved in cognitive flexibility.

  19. Spatial and Reversal Learning in the Morris Water Maze Are Largely Resistant to Six Hours of REM Sleep Deprivation Following Training

    Science.gov (United States)

    Walsh, Christine M.; Booth, Victoria; Poe, Gina R.

    2011-01-01

    This first test of the role of REM (rapid eye movement) sleep in reversal spatial learning is also the first attempt to replicate a much cited pair of papers reporting that REM sleep deprivation impairs the consolidation of initial spatial learning in the Morris water maze. We hypothesized that REM sleep deprivation following training would impair…

  20. Spatial and Reversal Learning in the Morris Water Maze Are Largely Resistant to Six Hours of REM Sleep Deprivation Following Training

    Science.gov (United States)

    Walsh, Christine M.; Booth, Victoria; Poe, Gina R.

    2011-01-01

    This first test of the role of REM (rapid eye movement) sleep in reversal spatial learning is also the first attempt to replicate a much cited pair of papers reporting that REM sleep deprivation impairs the consolidation of initial spatial learning in the Morris water maze. We hypothesized that REM sleep deprivation following training would impair…

  1. Expertise Reversal Effect and Sequencing of Learning Tasks in Online English as a Second Language Learning Environment

    Science.gov (United States)

    Song, Donggil

    2016-01-01

    The aim of this paper is to examine the effects of sequencing instructional materials and learners' prior knowledge on learning ESL (English as a second language) through an online learning course. 121 fifth-grade students from an elementary school in Korea participated in the study. Each participant was allocated to one cell of a 2 × 2…

  2. The Reverse Modality Effect: Examining Student Learning from Interactive Computer-Based Instruction

    Science.gov (United States)

    Inan, Fethi A.; Crooks, Steven M.; Cheon, Jongpil; Ari, Fatih; Flores, Raymond; Kurucay, Murat; Paniukov, Dmitrii

    2015-01-01

    The purpose of this study was to explore the effects of modality on learning from multimedia instruction. This study utilized a factorial between-subject design to examine the effects of modality on student learning outcomes, study patterns and mental effort. An interactive computer-presented diagram was developed to teach the places of…

  3. Lateral entorhinal modulation of piriform cortical activity and fine odor discrimination.

    Science.gov (United States)

    Chapuis, Julie; Cohen, Yaniv; He, Xiaobin; Zhang, Zhijan; Jin, Sen; Xu, Fuqiang; Wilson, Donald A

    2013-08-14

    The lateral entorhinal cortex (LEC) receives direct input from olfactory bulb mitral cells and piriform cortical pyramidal cells and is the gateway for olfactory input to the hippocampus. However, the LEC also projects back to the piriform cortex and olfactory bulb. Activity in the LEC is shaped by input from the perirhinal cortices, hippocampus, and amygdala, and thus could provide a rich contextual modulation of cortical odor processing. The present study further explored LEC feedback to anterior piriform cortex by examining how LEC top-down input modulates anterior piriform cortex odor evoked activity in rats. Retrograde viral tracing confirmed rich LEC projections to both the olfactory bulb and piriform cortices. In anesthetized rats, reversible lesions of the ipsilateral LEC increased anterior piriform cortical single-unit spontaneous activity. In awake animals performing an odor discrimination task, unilateral LEC reversible lesions enhanced ipsilateral piriform cortical local field potential oscillations during odor sampling, with minimal impact on contralateral activity. Bilateral LEC reversible lesions impaired discrimination performance on a well learned, difficult odor discrimination task, but had no impact on a well learned simple odor discrimination task. The simple discrimination task was impaired by bilateral reversible lesions of the anterior piriform cortex. Given the known function of LEC in working memory and multisensory integration, these results suggest it may serve as a powerful top-down modulator of olfactory cortical function and odor perception. Furthermore, the results provide potential insight into how neuropathology in the entorhinal cortex could contribute to early olfactory deficits seen in Alzheimer's disease.

  4. The effects of differential outcomes and different types of consequential stimuli on 7-year-old children's discriminative learning and memory.

    Science.gov (United States)

    Martínez, Lourdes; Flores, Pilar; González-Salinas, Carmen; Fuentes, Luis J; Estévez, Angeles F

    2013-09-01

    Researchers have demonstrated that discriminative learning is facilitated when a particular outcome is associated with each relation to be learned. Our primary purpose in the two experiments reported here was to assess whether the differential outcomes procedure (DOP) would enhance 7-year-old children's learning of symbolic discriminations using three different forms of consequences in which (1) reinforcers are given when correct choices are made ("+"), (2) reinforcers are withdrawn when errors are made ("-"), or (3) children receive a reinforcer following a correct choice and lose one following an incorrect choice ("+/-"), as well as different types of reinforcers (secondary and primary reinforcers, Experiment 1; primary reinforcers alone, Experiment 2). Participants learned the task faster and showed significantly better performance whenever differential outcomes were arranged independently of (1) the way of providing consequences (+, -, or +/-) and (2) the type of reinforcers being used. Interestingly, as in a previous study with 5-year-old children (Martínez, Estévez, Fuentes, & Overmier, The Quarterly Journal of Experimental Psychology 62(8):1617-1630, 2009), the use of the DOP also enhanced long-term persistence of learning.

  5. Dual learning processes underlying human decision-making in reversal learning tasks: Functional significance and evidence from the model fit to human behavior

    Directory of Open Access Journals (Sweden)

    Yu eBai

    2014-08-01

    Full Text Available Humans are capable of correcting their actions based on actions performed in the past, and this ability enables them to adapt to a changing environment. The computational field of reinforcement learning (RL has provided a powerful explanation for understanding such processes. Recently, the dual learning system, modeled as a hybrid model that incorporates value update based on reward-prediction error and learning rate modulation based on the surprise signal, has gained attention as a model for explaining various neural signals. However, the functional significance of the hybrid model has not been established. In the present study, we used computer simulation in a reversal learning task to address functional significance. The hybrid model was found to perform better than the standard RL model in a large parameter setting. These results suggest that the hybrid model is more robust against mistuning of parameters compared to the standard RL model when decision makers continue to learn stimulus-reward contingencies, which make an abrupt changes. The parameter fitting results also indicated that the hybrid model fit better than the standard RL model for more than 50% of the participants, which suggests that the hybrid model has more explanatory power for the behavioral data than the standard RL model.

  6. Lesions of the ventral midline thalamus produce deficits in reversal learning and attention on an odor texture set shifting task.

    Science.gov (United States)

    Linley, Stephanie B; Gallo, Michelle M; Vertes, Robert P

    2016-10-15

    The nucleus reuniens (RE) of the ventral midline thalamus is strongly reciprocally connected with the hippocampus (HF) and the medial prefrontal cortex (mPFC) and has been shown to mediate the transfer of information between these structures. It has become increasingly well established that RE serves a critical role in mnemonic tasks requiring the interaction of the HF and mPFC, but essentially not tasks relying solely on the HF. Very few studies have addressed the independent actions of RE on prefrontal executive functioning. The present report examined the effects of lesions of the ventral midline thalamus, including RE and the dorsally adjacent rhomboid nucleus (RH) in rats on attention and behavioral flexibility using the attentional set shifting task (AST). The task uses odor and tactile stimuli to test for attentional set formation, attentional set shifting, behavioral flexibility and reversal learning. By comparison with sham controls, lesioned rats were significantly impaired on reversal learning and intradimensional (ID) set shifting. Specifically, RE/RH lesioned rats were impaired on the first reversal stage of the task which required a change in response strategy to select a previously non-rewarded stimulus for reward. RE/RH lesioned rats also exhibited deficits in the ability to transfer or generalize rules of the task which requires making the same modality-based choices (e.g., odor vs. tactile) to different sets of stimuli in the ID stage of the task. These results demonstrate that in addition to its role in tasks dependent on HF-mPFC interactions, nucleus reuniens is also critically involved cognitive/executive functions associated with the medial prefrontal cortex. As such, the deficits in the AST task produced by RE/RH lesions suggest the ventral midline thalamus directly contributes to flexible goal directed behavior. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Hyperammonemia induces glial activation, neuroinflammation and alters neurotransmitter receptors in hippocampus, impairing spatial learning: reversal by sulforaphane.

    Science.gov (United States)

    Hernández-Rabaza, Vicente; Cabrera-Pastor, Andrea; Taoro-González, Lucas; Malaguarnera, Michele; Agustí, Ana; Llansola, Marta; Felipo, Vicente

    2016-02-16

    -inflammatory M2 phenotype and reduces activation of astrocytes in hyperammonemic rats. This reduces neuroinflammation, normalizes membrane expression of glutamate and GABA receptors, and restores spatial learning in hyperammonemic rats. Hyperammonemia-induced neuroinflammation impairs glutamatergic and GABAergic neurotransmission by altering membrane expression of glutamate and GABA receptors, resulting in impaired spatial learning. Sulforaphane reverses all these effects. Treatment with sulforaphane could be useful to improve cognitive function in cirrhotic patients with minimal or clinical hepatic encephalopathy.

  8. Strains and stressors: an analysis of touchscreen learning in genetically diverse mouse strains.

    Directory of Open Access Journals (Sweden)

    Carolyn Graybeal

    Full Text Available Touchscreen-based systems are growing in popularity as a tractable, translational approach for studying learning and cognition in rodents. However, while mouse strains are well known to differ in learning across various settings, performance variation between strains in touchscreen learning has not been well described. The selection of appropriate genetic strains and backgrounds is critical to the design of touchscreen-based studies and provides a basis for elucidating genetic factors moderating behavior. Here we provide a quantitative foundation for visual discrimination and reversal learning using touchscreen assays across a total of 35 genotypes. We found significant differences in operant performance and learning, including faster reversal learning in DBA/2J compared to C57BL/6J mice. We then assessed DBA/2J and C57BL/6J for differential sensitivity to an environmental insult by testing for alterations in reversal learning following exposure to repeated swim stress. Stress facilitated reversal learning (selectively during the late stage of reversal in C57BL/6J, but did not affect learning in DBA/2J. To dissect genetic factors underlying these differences, we phenotyped a family of 27 BXD strains generated by crossing C57BL/6J and DBA/2J. There was marked variation in discrimination, reversal and extinction learning across the BXD strains, suggesting this task may be useful for identifying underlying genetic differences. Moreover, different measures of touchscreen learning were only modestly correlated in the BXD strains, indicating that these processes are comparatively independent at both genetic and phenotypic levels. Finally, we examined the behavioral structure of learning via principal component analysis of the current data, plus an archival dataset, totaling 765 mice. This revealed 5 independent factors suggestive of "reversal learning," "motivation-related late reversal learning," "discrimination learning," "speed to respond," and

  9. Strains and stressors: an analysis of touchscreen learning in genetically diverse mouse strains.

    Science.gov (United States)

    Graybeal, Carolyn; Bachu, Munisa; Mozhui, Khyobeni; Saksida, Lisa M; Bussey, Timothy J; Sagalyn, Erica; Williams, Robert W; Holmes, Andrew

    2014-01-01

    Touchscreen-based systems are growing in popularity as a tractable, translational approach for studying learning and cognition in rodents. However, while mouse strains are well known to differ in learning across various settings, performance variation between strains in touchscreen learning has not been well described. The selection of appropriate genetic strains and backgrounds is critical to the design of touchscreen-based studies and provides a basis for elucidating genetic factors moderating behavior. Here we provide a quantitative foundation for visual discrimination and reversal learning using touchscreen assays across a total of 35 genotypes. We found significant differences in operant performance and learning, including faster reversal learning in DBA/2J compared to C57BL/6J mice. We then assessed DBA/2J and C57BL/6J for differential sensitivity to an environmental insult by testing for alterations in reversal learning following exposure to repeated swim stress. Stress facilitated reversal learning (selectively during the late stage of reversal) in C57BL/6J, but did not affect learning in DBA/2J. To dissect genetic factors underlying these differences, we phenotyped a family of 27 BXD strains generated by crossing C57BL/6J and DBA/2J. There was marked variation in discrimination, reversal and extinction learning across the BXD strains, suggesting this task may be useful for identifying underlying genetic differences. Moreover, different measures of touchscreen learning were only modestly correlated in the BXD strains, indicating that these processes are comparatively independent at both genetic and phenotypic levels. Finally, we examined the behavioral structure of learning via principal component analysis of the current data, plus an archival dataset, totaling 765 mice. This revealed 5 independent factors suggestive of "reversal learning," "motivation-related late reversal learning," "discrimination learning," "speed to respond," and "motivation during

  10. Price Discrimination

    OpenAIRE

    Armstrong, Mark

    2008-01-01

    This paper surveys recent economic research on price discrimination, both in monopoly and oligopoly markets. Topics include static and dynamic forms of price discrimination, and both final and input markets are considered. Potential antitrust aspects of price discrimination are highlighted throughout the paper. The paper argues that the informational requirements to make accurate policy are very great, and with most forms of price discrimination a laissez-faire policy may be the best availabl...

  11. Changes in cortical field potentials during learning processes of go/no-go reaction time hand movement with tone discrimination in the monkey.

    Science.gov (United States)

    Gemba, H

    1993-09-03

    Field potentials were recorded with electrodes implanted in various cortical areas while a monkey acquired a task of go/no-go reaction time hand movement with discrimination between tone stimuli of different frequencies. After a few weeks of training, a surface-negative, depth-positive (s-N, d-P) potential (no-go potential) emerged in the dorsal bank of the principal sulcus. As the potential increased in size in 1-3 months, the monkey gradually discriminated between go and no-go stimuli. The no-go potential is considered to be related to judgement not to move and suppression of motor execution. In the superior temporal gyrus, a s-N, d-P potential at a shorter latency than the no-go potential augmented in size on both go and no-go trials, as the monkey learned the discrimination task. The s-N, d-P potential in this gyrus may reflect an information processing prior to the discrimination in the prefrontal cortex.

  12. An Evaluation of Active Learning Causal Discovery Methods for Reverse-Engineering Local Causal Pathways of Gene Regulation.

    Science.gov (United States)

    Ma, Sisi; Kemmeren, Patrick; Aliferis, Constantin F; Statnikov, Alexander

    2016-03-04

    Reverse-engineering of causal pathways that implicate diseases and vital cellular functions is a fundamental problem in biomedicine. Discovery of the local causal pathway of a target variable (that consists of its direct causes and direct effects) is essential for effective intervention and can facilitate accurate diagnosis and prognosis. Recent research has provided several active learning methods that can leverage passively observed high-throughput data to draft causal pathways and then refine the inferred relations with a limited number of experiments. The current study provides a comprehensive evaluation of the performance of active learning methods for local causal pathway discovery in real biological data. Specifically, 54 active learning methods/variants from 3 families of algorithms were applied for local causal pathways reconstruction of gene regulation for 5 transcription factors in S. cerevisiae. Four aspects of the methods' performance were assessed, including adjacency discovery quality, edge orientation accuracy, complete pathway discovery quality, and experimental cost. The results of this study show that some methods provide significant performance benefits over others and therefore should be routinely used for local causal pathway discovery tasks. This study also demonstrates the feasibility of local causal pathway reconstruction in real biological systems with significant quality and low experimental cost.

  13. Anatomy of a Decision: Striato-Orbitofrontal Interactions in Reinforcement Learning, Decision Making, and Reversal

    Science.gov (United States)

    Frank, Michael J.; Claus, Eric D.

    2006-01-01

    The authors explore the division of labor between the basal ganglia-dopamine (BG-DA) system and the orbitofrontal cortex (OFC) in decision making. They show that a primitive neural network model of the BG-DA system slowly learns to make decisions on the basis of the relative probability of rewards but is not as sensitive to (a) recency or (b) the…

  14. Establishing the dopamine dependency of human striatal signals during reward and punishment reversal learning

    NARCIS (Netherlands)

    Schaaf, M.E. van der; Schouwenburg, M.R. van; Geurts, D.E.M.; Schellekens, A.F.A.; Buitelaar, J.; Verkes, R.J.; Cools, R.

    2014-01-01

    Drugs that alter dopamine transmission have opposite effects on reward and punishment learning. These opposite effects have been suggested to depend on dopamine in the striatum. Here, we establish for the first time the neurochemical specificity of such drug effects, during reward and punishment lea

  15. Feedback-related negativity codes outcome valence, but not outcome expectancy, during reversal learning

    NARCIS (Netherlands)

    Borries, A.K.L. von; Verkes, R.J.; Bulten, B.H.; Cools, R.; Bruijn, E.R. de

    2013-01-01

    Optimal behavior depends on the ability to assess the predictive value of events and to adjust behavior accordingly. Outcome processing can be studied by using its electrophysiological signatures-that is, the feedback-related negativity (FRN) and the P300. A prominent reinforcement-learning model pr

  16. Feedback-related negativity codes outcome valence, but not outcome expectancy, during reversal learning

    NARCIS (Netherlands)

    Borries, A.K.L. von; Verkes, R.J.; Bulten, B.H.; Cools, R.

    2013-01-01

    Optimal behavior depends on the ability to assess the predictive value of events and to adjust behavior accordingly. Outcome processing can be studied by using its electrophysiological signatures--that is, the feedback-related negativity (FRN) and the P300. A prominent reinforcement-learning model p

  17. Regionally distinct phasic dopamine release patterns in the striatum during reversal learning

    NARCIS (Netherlands)

    Klanker, Marianne; Fellinger, Lisanne; Feenstra, M.G.P.; Willuhn, Ingo; Denys, D.

    2017-01-01

    Striatal dopamine (DA) plays a central role in reward-related learning and behavioral adaptation to changing environments. Recent studies suggest that rather than being broadcast as a uniform signal throughout the entire region, DA release dynamics diverge between different striatal regions. In a pr

  18. Genetic Inactivation of D-Amino Acid Oxidase Enhances Extinction and Reversal Learning in Mice

    Science.gov (United States)

    Labrie, Viviane; Duffy, Steven; Wang, Wei; Barger, Steven W.; Baker, Glen B.; Roder, John C.

    2009-01-01

    Activation of the N-methyl-d-aspartate receptor (NMDAR) glycine site has been shown to accelerate adaptive forms of learning that may benefit psychopathologies involving cognitive and perseverative disturbances. In this study, the effects of increasing the brain levels of the endogenous NMDAR glycine site agonist D-serine, through the genetic…

  19. Reversing the Truth Effect: Learning the Interpretation of Processing Fluency in Judgments of Truth

    Science.gov (United States)

    Unkelbach, Christian

    2007-01-01

    Repeated statements receive higher truth ratings than new statements. Given that repetition leads to greater experienced processing fluency, the author proposes that fluency is used in truth judgments according to its ecological validity. Thus, the truth effect occurs because people learn that fluency and truth tend to be positively correlated.…

  20. Reversing the Export of People with Learning Disabilities and Complex Health Needs

    Science.gov (United States)

    Pritchard, Andrew; Roy, Ashok

    2006-01-01

    Background: There is an increase in people with learning disabilities with offending and other disturbed behaviour who are placed in the local community and out of their area of origin. Aims: To compare clients placed locally and out of area. Method: All authorities in an English region were surveyed and interviewed about their clients placed…

  1. Reversal of Motor Learning in the Vestibulo-Ocular Reflex in the Absence of Visual Input

    Science.gov (United States)

    Cohen, Marlene R.; Meissner, Geoffrey W.; Schafer, Robert J.; Raymond, Jennifer L.

    2004-01-01

    Motor learning in the vestibulo-ocular reflex (VOR) and eyeblink conditioning use similar neural circuitry, and they may use similar cellular plasticity mechanisms. Classically conditioned eyeblink responses undergo extinction after prolonged exposure to the conditioned stimulus in the absence of the unconditioned stimulus. We investigated the…

  2. Structural Discrimination

    DEFF Research Database (Denmark)

    Thorsen, Mira Skadegård

    In this article, I discuss structural discrimination, an underrepresented area of study in Danish discrimination and intercultural research. It is defined here as discursive and constitutive, and presented as a central element of my analytical approach. This notion is employed in the with which...... to understand and identify aspects of power and asymmetry in communication and interactions. With this as a defining term, I address how exclusion and discrimination exist, while also being indiscernible, within widely accepted societal norms. I introduce the concepts of microdiscrimination and benevolent...... discrimination as two ways of articulating particular, opaque forms of racial discrimination that occur in everyday Danish (and other) contexts, and have therefore become normalized. I present and discuss discrimination as it surfaces in data from my empirical studies of discrimination in Danish contexts...

  3. Discrimination in Recruitment: An Empirical Analysis.

    Science.gov (United States)

    Newman, Jerry M.

    1978-01-01

    To investigate whether recruitment practices of companies with affirmative action programs discriminated against Blacks or resulted in reverse discrimination, qualifications and race of fictitious job applicants were manipulated on resumes sent to a sample of employers. Responses strongly indicate discrimination, with Black applicants favored…

  4. Depression-biased reverse plasticity rule is required for stable learning at top-down connections.

    Directory of Open Access Journals (Sweden)

    Kendra S Burbank

    Full Text Available Top-down synapses are ubiquitous throughout neocortex and play a central role in cognition, yet little is known about their development and specificity. During sensory experience, lower neocortical areas are activated before higher ones, causing top-down synapses to experience a preponderance of post-synaptic activity preceding pre-synaptic activity. This timing pattern is the opposite of that experienced by bottom-up synapses, which suggests that different versions of spike-timing dependent synaptic plasticity (STDP rules may be required at top-down synapses. We consider a two-layer neural network model and investigate which STDP rules can lead to a distribution of top-down synaptic weights that is stable, diverse and avoids strong loops. We introduce a temporally reversed rule (rSTDP where top-down synapses are potentiated if post-synaptic activity precedes pre-synaptic activity. Combining analytical work and integrate-and-fire simulations, we show that only depression-biased rSTDP (and not classical STDP produces stable and diverse top-down weights. The conclusions did not change upon addition of homeostatic mechanisms, multiplicative STDP rules or weak external input to the top neurons. Our prediction for rSTDP at top-down synapses, which are distally located, is supported by recent neurophysiological evidence showing the existence of temporally reversed STDP in synapses that are distal to the post-synaptic cell body.

  5. Flipping The Classroom: How Reversing Teaching-Learning Process Can Improve Learner’s Comprehension in Learning Foreign Language

    Directory of Open Access Journals (Sweden)

    Wishnoebroto Wishnoebroto

    2014-10-01

    Full Text Available Flipping a classroom is not only recording classroom lesson into a video and bringing homework into the classroom. It is a whole new method with a lot better result compared to the traditional method. In western countries such as the US, flipping a classroom is already becoming a new method adopted by many different schools and universities. This paper tries to explore the possibility of flipping a classroom for learning foreign language at BINUS University by comparing it with the recent practices and findings in the western countries. After the analysis it can be concluded that this method can be applied at BINUS University but on several conditions such as the improvement of infrastructures, and the teacher’s awareness and understanding to optimize their understanding about flipped learning

  6. 可区分惩罚控制竞争学习算法%Discriminative Rival Penalization Controlled Competitive Learning Algorithm

    Institute of Scientific and Technical Information of China (English)

    张锋; 赵杰煜; 朱绍军

    2014-01-01

    Competitive learning is an important approach for clustering analysis. The rival penalized competitive learning ( RPCL) algorithm has the ability of selecting the correct number of clusters automatically, but its performance is sensitive to the selection of learning rate and de-learning rate. In fact, it is unreasonable that all the rival units are treated as redundant units to be penalized in the variant algorithm called rival penalization controlled competitive learning ( RPCCL) . In this paper, a discriminative rival penalization controlled competitive learning ( DRPCCL) is presented. The learning rate of winning units adaptively adjusts during iteration in the proposed method. Meanwhile, a discriminative penalization controlled mechanism is used to discriminate the redundant units and the correct units in the rival units. The correct units and redundant units are given a slight penalization and a heavier penalization respectively, which makes this algorithm get exact number of clusters and reasonable centre of clusters. The experimental result demonstrates that compared with RPCL and RPCCL, DRPCCL achieves more accurate performance.%竞争学习在聚类分析中是一种重要的学习方式,次胜者惩罚竞争学习( RPCL)算法虽能自动选择合理的类别数,但其性能对学习率和惩罚率的取值较敏感,其变种惩罚控制竞争学习( RPCCL)算法将所有的竞争单元当成冗余单元进行惩罚也不合理。文中提出一种可区分惩罚控制竞争学习算法( DRPCCL)。算法中获胜单元的学习率会在迭代过程中自适应调整。同时该算法使用一种可区分惩罚控制机制来区分竞争单元中的冗余单元和正确单元,给予冗余单元较重惩罚,正确单元轻微惩罚,使得算法能自动确定正确类别数和中心点位置。最后通过实验对比分析证明DRPCCL算法的聚类效果比RPCL算法和RPCCL算法更准确。

  7. 2-Methyl-6-(phenylethynyl pyridine (MPEP reverses maze learning and PSD-95 deficits in Fmr1 knock-out mice.

    Directory of Open Access Journals (Sweden)

    Réno Michelle Gandhi

    2014-03-01

    Full Text Available Fragile X syndrome (FXS is caused by the lack of expression of the fragile X mental retardation protein (FMRP, which results in intellectual disability and other debilitating symptoms including impairment of visual-spatial functioning. FXS is the only single-gene disorder that is highly co-morbid with autism spectrum disorder and can therefore provide insight into its pathophysiology. Lack of FMRP results in altered group I metabotropic glutamate receptor (mGluR signalling, which is a target for putative treatments. The Hebb-Williams (H-W mazes are a set of increasingly complex spatial navigation problems that depend on intact hippocampal and thus mGluR-5 functioning. In the present investigation, we examined whether an antagonist of mGluR-5 would reverse previously described behavioural deficits in Fmr1 KO mice. Mice were trained on a subset of the H-W mazes and then treated with either 20 mg/kg of an mGluR-5 antagonist, 2-Methyl-6-(phenylethynyl pyridine (MPEP; n = 11 or an equivalent dose of saline (n = 11 prior to running test mazes. Latency and errors were dependent variables recorded during the test phase. Immediately after completing each test, marble-burying behavior was assessed which confirmed that the drug treatment was pharmacologically active during maze learning. Although latency was not statistically different between the groups, MPEP treated Fmr1 KO mice made significantly fewer errors on mazes deemed more difficult suggesting a reversal of the behavioural deficit. MPEP treated mice were also less perseverative and impulsive when navigating mazes. Furthermore, MPEP treatment reversed PSD-95 protein deficits in Fmr1 KO treated mice, whereas levels of a control protein (β-tubulin remained unchanged. These data further validate MPEP as a potentially beneficial treatment for FXS. Our findings also suggest that adapted H-W mazes may be a useful tool to document alterations in behavioural functioning following pharmacological

  8. Fast reversible learning based on neurons functioning as anisotropic multiplex hubs

    Science.gov (United States)

    Vardi, Roni; Goldental, Amir; Sheinin, Anton; Sardi, Shira; Kanter, Ido

    2017-05-01

    Neural networks are composed of neurons and synapses, which are responsible for learning in a slow adaptive dynamical process. Here we experimentally show that neurons act like independent anisotropic multiplex hubs, which relay and mute incoming signals following their input directions. Theoretically, the observed information routing enriches the computational capabilities of neurons by allowing, for instance, equalization among different information routes in the network, as well as high-frequency transmission of complex time-dependent signals constructed via several parallel routes. In addition, this kind of hubs adaptively eliminate very noisy neurons from the dynamics of the network, preventing masking of information transmission. The timescales for these features are several seconds at most, as opposed to the imprint of information by the synaptic plasticity, a process which exceeds minutes. Results open the horizon to the understanding of fast and adaptive learning realities in higher cognitive brain's functionalities.

  9. K70Q adds high-level tenofovir resistance to "Q151M complex" HIV reverse transcriptase through the enhanced discrimination mechanism.

    Directory of Open Access Journals (Sweden)

    Atsuko Hachiya

    Full Text Available HIV-1 carrying the "Q151M complex" reverse transcriptase (RT mutations (A62V/V75I/F77L/F116Y/Q151M, or Q151Mc is resistant to many FDA-approved nucleoside RT inhibitors (NRTIs, but has been considered susceptible to tenofovir disoproxil fumarate (TFV-DF or TDF. We have isolated from a TFV-DF-treated HIV patient a Q151Mc-containing clinical isolate with high phenotypic resistance to TFV-DF. Analysis of the genotypic and phenotypic testing over the course of this patient's therapy lead us to hypothesize that TFV-DF resistance emerged upon appearance of the previously unreported K70Q mutation in the Q151Mc background. Virological analysis showed that HIV with only K70Q was not significantly resistant to TFV-DF. However, addition of K70Q to the Q151Mc background significantly enhanced resistance to several approved NRTIs, and also resulted in high-level (10-fold resistance to TFV-DF. Biochemical experiments established that the increased resistance to tenofovir is not the result of enhanced excision, as K70Q/Q151Mc RT exhibited diminished, rather than enhanced ATP-based primer unblocking activity. Pre-steady state kinetic analysis of the recombinant enzymes demonstrated that addition of the K70Q mutation selectively decreases the binding of tenofovir-diphosphate (TFV-DP, resulting in reduced incorporation of TFV into the nascent DNA chain. Molecular dynamics simulations suggest that changes in the hydrogen bonding pattern in the polymerase active site of K70Q/Q151Mc RT may contribute to the observed changes in binding and incorporation of TFV-DP. The novel pattern of TFV-resistance may help adjust therapeutic strategies for NRTI-experienced patients with multi-drug resistant (MDR mutations.

  10. Diminished acquired equivalence yet good discrimination performance in older participants

    Directory of Open Access Journals (Sweden)

    Jasper eRobinson

    2013-10-01

    Full Text Available We asked younger and older human participants to perform computer-based configural discriminations that were designed to detect acquired equivalence. Both groups solved the discriminations but only the younger participants demonstrated acquired equivalence. The discriminations involved learning the preferences (‘like’ [+] or ‘dislike’ [-] for sports (e.g., tennis [t] and hockey [h] of four fictitious people (e.g., Alice [A], Beth [B], Charlotte [C] & Dorothy [D]. In one experiment, the discrimination had the form: At+, Bt-, Ct+, Dt-, Ah-, Bh+, Ch-, Dh+. Notice that, e.g., Alice and Charlotte are ‘equivalent’ in liking tennis but disliking hockey. Acquired equivalence was assessed in ancillary components of the discrimination (e.g., by looking at the subsequent rate of ‘whole’ versus ‘partial’ reversal learning. Acquired equivalence is anticipated by a network whose hidden units are shared when inputs (e.g., A and C signal the same outcome (e.g., + when accompanied by the same input (t. One interpretation of these results is that there are age-related differences in the mechanisms of configural acquired equivalence.

  11. Diminished acquired equivalence yet good discrimination performance in older participants.

    Science.gov (United States)

    Robinson, Jasper; Owens, Emma

    2013-01-01

    We asked younger and older human participants to perform computer-based configural discriminations that were designed to detect acquired equivalence. Both groups solved the discriminations but only the younger participants demonstrated acquired equivalence. The discriminations involved learning the preferences ["like" (+) or "dislike" (-)] for sports [e.g., tennis (t) and hockey (h)] of four fictitious people [e.g., Alice (A), Beth (B), Charlotte (C), and Dorothy (D)]. In one experiment, the discrimination had the form: At+, Bt-, Ct+, Dt-, Ah-, Bh+, Ch-, Dh+. Notice that, e.g., Alice and Charlotte are "equivalent" in liking tennis but disliking hockey. Acquired equivalence was assessed in ancillary components of the discrimination (e.g., by looking at the subsequent rate of "whole" versus "partial" reversal learning). Acquired equivalence is anticipated by a network whose hidden units are shared when inputs (e.g., A and C) signal the same outcome (e.g., +) when accompanied by the same input (t). One interpretation of these results is that there are age-related differences in the mechanisms of configural acquired equivalence.

  12. A Lesson in Discrimination.

    Science.gov (United States)

    Chotiner, Barbara; Hameroff-Cohen, Wendy

    1994-01-01

    Public high school students with deafness vividly learned about the realities of discrimination when they were informed of "new rules for deaf students," which required that they wear "deaf badges" in school, follow a strict dress code, and so on. After the "new rules" hoax was revealed, students' feelings and reactions to the situation were…

  13. Cognitive aspects of congenital learned helplessness and its reversal by the monoamine oxidase (MAO)-B inhibitor deprenyl

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, D.; Schulz, D.; Mirrione, M.; Henn, F.A.

    2009-11-29

    Cognitive processes are assumed to change with learned helplessness, an animal model of depression, but little is known about such deficits. Here we investigated the role of cognitive and related functions in selectively bred helpless (cLH, n = 10), non-helpless (cNLH, n = 12) and wild type (WT, n = 8) Sprague Dawley rats. The animals were exposed to an open field for 10 min on each of two test days. On the third day, an object exploration paradigm was carried out. The animals were later tested for helplessness. Both cLH and cNLH rats were more active than WTs on the first day in the open field. Over trials, cNLH and WT rats lowered their activity less than cLH rats. This resistance-to-habituation co-varied with a resistance to develop helplessness. In cLH rats, higher 'anxiety' or less time spent in the center of the open field co-varied with severe helplessness. In WTs, a greater reactivity to novel objects and to a spatially relocated object predicted lower levels of helplessness. In cLH rats (n = 4-5 per group), chronic treatment with a high dose of the monoamineoxidase (MAO)-Binhibitordeprenyl (10 mg/kg; i.p.), an anti-Parkinson, nootropic and antidepressant drug, attenuated helplessness. Remarkably, helplessness reversal required the experience of repeated test trials, reminiscent of a learning process. Chronic deprenyl (10 mg/kg; i.p.) did not alter locomotion/exploration or 'anxiety' in the open field. In conclusion, helplessness may be related to altered mechanisms of reinforcement learning and working memory, and to abnormalities in MAO-A and/or MAO-B functioning.

  14. Learning to cope with degraded sounds: female zebra finches can improve their expertise in discriminating between male voices at long distances.

    Science.gov (United States)

    Mouterde, Solveig C; Elie, Julie E; Theunissen, Frédéric E; Mathevon, Nicolas

    2014-09-01

    Reliable transmission of acoustic information about individual identity is of critical importance for pair bond maintenance in numerous monogamous songbirds. However, information transfer can be impaired by environmental constraints such as external noise or propagation-induced degradation. Birds have been shown to use several adaptive strategies to deal with difficult signal transmission contexts. Specifically, a number of studies have suggested that vocal plasticity at the emitter's level allows birds to counteract the deleterious effects of sound degradation. Although the communication process involves both the emitter and the receiver, perceptual plasticity at the receiver's level has received little attention. Here, we explored the reliability of individual recognition by female zebra finches (Taeniopygia guttata), testing whether perceptual training can improve discrimination of degraded individual vocal signatures. We found that female zebra finches are proficient in discriminating between calls of individual males at long distances, and even more so when they can train themselves with increasingly degraded signals over time. In this latter context, females succeed in discriminating between males as far as 250 m. This result emphasizes that adaptation to adverse communication conditions may involve not only the emitter's vocal plasticity but also the receptor's decoding process through on-going learning. © 2014. Published by The Company of Biologists Ltd.

  15. Variable Selection in Discriminant Analysis.

    Science.gov (United States)

    Huberty, Carl J.; Mourad, Salah A.

    Methods for ordering and selecting variables for discriminant analysis in multiple group comparison or group prediction studies include: univariate Fs, stepwise analysis, learning discriminant function (LDF) variable correlations, communalities, LDF standardized coefficients, and weighted standardized coefficients. Five indices based on distance,…

  16. Variable Selection in Discriminant Analysis.

    Science.gov (United States)

    Huberty, Carl J.; Mourad, Salah A.

    Methods for ordering and selecting variables for discriminant analysis in multiple group comparison or group prediction studies include: univariate Fs, stepwise analysis, learning discriminant function (LDF) variable correlations, communalities, LDF standardized coefficients, and weighted standardized coefficients. Five indices based on distance,…

  17. Addressing Discrimination in School Matters!

    Science.gov (United States)

    Sullivan, Amanda L.

    2009-01-01

    Every student has the right to an education free from discrimination that provides high-quality, equitable opportunities to learn. Unfortunately, sometimes individuals or systems may act in ways that violate this right. Discrimination occurs when people are treated unequally or less favorably than others because of some real or perceived…

  18. Discriminant Manifold Learning Approach for Hyperspectral Image Dimension Reduction%高光谱图像降维的判别流形学习方法

    Institute of Scientific and Technical Information of China (English)

    杜博; 张乐飞; 张良培; 胡文斌

    2013-01-01

    A discriminant manifold learning approach for hyperspectral image dimension reduction was proposed. In order to overcome the high dimensional and high redundancy of remotely sensed earth observation images, a modified manifold learning algorithm was suggested for dataset linear dimensional reduction to improve the performance of image classification. The proposed method addressed the discriminative information of given training samples into the current manifold learning framework to learn an optimal subspace for subsequent classification, in particular, the linearization of discriminant manifold learning is introduced to deal with the out of sample problem. Experiments on hyperspectral image demonstrated that the proposed method could achieve higher classification rate than the conventional image classification technologies.%本文提出了一种高光谱图像降维的判别流形学习方法.针对获取的大量遥感对地观测数据存在大量冗余信息的特点,引入改进的流形学习方法对高光谱遥感数据进行降维处理,以提高遥感图像自动分类的总体准确度.该方法充分利用遥感图像自动分类中训练样本的判别信息,将输入样本的类别信息加入到常规流形学习方法的框架中,从本质上提高输出的特征在低维空间中的判别力.同时,引入线性化模型以解决流形学习方法中常见的小样本问题.对高光谱遥感图像自动分类的实验表明,基于判别流形学习的高光谱遥感图像自动分类方法能够显著地提高图像分类准确度.

  19. Teaching Children with Autism to Discriminate the Reinforced and Nonreinforced Responses of Others: Implications for Observational Learning

    Science.gov (United States)

    DeQuinzio, Jaime Ann; Taylor, Bridget A.

    2015-01-01

    We taught 4 participants with autism to discriminate between the reinforced and nonreinforced responses of an adult model and evaluated the effectiveness of this intervention using a multiple baseline design. During baseline, participants were simply exposed to adult models' correct and incorrect responses and the respective consequences of each.…

  20. Teratology, survival, and reversal learning after fetal irradiation of mice by 2450-MHz microwave energy

    Energy Technology Data Exchange (ETDEWEB)

    Chernovetz, M.E. (Univ. of Tulsa, OK); Justesen, D.R.; King, N.W.; Wagner, J.E.

    1975-12-01

    Eighty primigravid mice of the C3H-HeJ strain were subjected to 2450-MHz sinusoidally modulated microwave radiation or to sham radiation (with or without an accompanying injection of 5 mg of cortisone as a teratological marker) on the 11th, 12th, 13th or 14th day of gestation. The radiation treatment consisted of a single intense dosing of microwave energy (38 mW/g for 600 sec = 22.8 J/g) in a multi-mode cavity. On the 19th day of gestation fetuses were taken via Caesarean section and were observed for gross structural abnormalities. While radiation of dams failed reliably to increase the incidence of fetal mortality or morbidity above that of controls, the dams treated with cortisone gave birth to reliably greater numbers of stillborn and deformed fetuses. During their 14th day of gestation 60 primigravid mice received the radiation or sham-radiation treatment, half with and half without the accompanying injection of cortisone. A virtually complete failure to survive to weaning characterized the pups born of the sham-radiated cortisone-treated group of dams, but the incidence of cortisone-induced mortality was reliably reduced in pups whose dams were also radiated by microwave energy. No differences in maze performances were observed in the mice as a function of their placement in the control or the radiation condition, but offspring of cortisone-treated, radiated dams made reliably more errors. Careful measurement of elevations of colonic temperatures of radiated dams shortly after treatment with cortisone revealed an averaged ..delta..T that is close to that observed in a comparably radiated volume of water of equivalent mass. If the finding has generality beyond the gravid mouse--if, that is, cortisone effectively and reversibly renders the mammal ectothermic--an important advance in biological dosimetry of non-ionizing radiation may be at hand.

  1. Age-associated changes in the hippocampal-ventral striatum-ventral tegmental loop that impact learning, prediction and context discrimination

    Directory of Open Access Journals (Sweden)

    Marsha R Penner

    2012-08-01

    Full Text Available Studies of the neural mechanisms of navigation and context discrimination have generated a powerful heuristic for understanding how neural codes, circuits and computations contribute to accurate behavior as animals traverse and learn about spatially-extended environments. It is assumed that memories are updated as a result of spatial experience. The mechanism, however, for such a process is not clear. Here we suggest that one revealing approach to study this issue is to integrate our knowledge about limbic system mediated navigation and context discrimination with knowledge about how midbrain neural circuitry mediates decision making. This perspective should lead to new and specific neural theories about how choices that we make during navigation determine what information is ultimately learned and remembered. This same circuitry may be involved when past experiences come to bias future spatial perceptions and response selection. With old age come not only important changes in limbic system operations, but also significant decline in the function of midbrain regions that underlie accurate and efficient decisions. Thus suboptimal accuracy of spatial context-based decision making may be at least in part responsible for the common observation of spatial memory decline in old age.

  2. Reversal of Trimethyltin-Induced Learning and Memory Deficits by 3,5-Dicaffeoylquinic Acid

    Directory of Open Access Journals (Sweden)

    Jin Yong Kang

    2016-01-01

    Full Text Available The antiamnesic effect of 3,5-dicaffeoylquinic acid (3,5-diCQA as the main phenolic compound in Artemisia argyi H. extract on cognitive dysfunction induced by trimethyltin (TMT (7.1 μg/kg of body weight; intraperitoneal injection was investigated in order to assess its ameliorating function in mice. In several behavioral tests, namely, the Y-maze, passive avoidance, and Morris water maze (MWM test, 3,5-diCQA significantly ameliorated learning and memory deficits. After the behavioral tests, brain tissues from the mice were analyzed to characterize the basis of the neuroprotective effect. Acetylcholine (ACh levels increased, whereas the activity of acetylcholinesterase (AChE decreased upon administration of 3,5-diCQA. In addition, 3,5-diCQA effectively protected against an increase in malondialdehyde (MDA content, an increase in the oxidized glutathione (GSH ratio, and a decline of total superoxide dismutase (SOD level. 3,5-diCQA may prevent neuronal apoptosis through the protection of mitochondrial activities and the repression of apoptotic signaling molecules such as p-Akt, BAX, and p-tau (Ser 404.

  3. The application of discriminant analysis and Machine Learning methods as tools to identify and classify compounds with potential as transdermal enhancers.

    Science.gov (United States)

    Moss, G P; Shah, A J; Adams, R G; Davey, N; Wilkinson, S C; Pugh, W J; Sun, Y

    2012-01-23

    Discriminant analysis (DA) has previously been shown to allow the proposal of simple guidelines for the classification of 73 chemical enhancers of percutaneous absorption. Pugh et al. employed DA to classify such enhancers into simple categories, based on the physicochemical properties of the enhancer molecules (Pugh et al., 2005). While this approach provided a reasonable accuracy of classification it was unable to provide a consistently reliable estimate of enhancement ratio (ER, defined as the amount of hydrocortisone transferred after 24h, relative to control). Machine Learning methods, including Gaussian process (GP) regression, have recently been employed in the prediction of percutaneous absorption of exogenous chemicals (Moss et al., 2009; Lam et al., 2010; Sun et al., 2011). They have shown that they provide more accurate predictions of these phenomena. In this study several Machine Learning methods, including the K-nearest-neighbour (KNN) regression, single layer networks, radial basis function networks and the SVM classifier were applied to an enhancer dataset reported previously. The SMOTE sampling method was used to oversample chemical compounds with ER>10 in each training set in order to improve estimation of GP and KNN. Results show that models using five physicochemical descriptors exhibit better performance than those with three features. The best classification result was obtained by using the SVM method without dealing with imbalanced data. Following over-sampling, GP gives the best result. It correctly assigned 8 of the 12 "good" (ER>10) enhancers and 56 of the 59 "poor" enhancers (ERMachine Learning methods are that they can provide more accurate classification of enhancer type with fewer false-positive results and that, unlike discriminant analysis, they are able to make predictions of enhancer ability.

  4. Intra-orbitofrontal cortex injection of haloperidol removes the beneficial effect of methylphenidate on reversal learning of spontaneously hypertensive rats in an attentional set-shifting task.

    Science.gov (United States)

    Cheng, Jen-Tang; Li, Jay-Shake

    2013-02-15

    Numerous studies suggest that attention-deficit/hyperactivity disorder (ADHD) is caused by deficits in catecholaminergic systems. Furthermore, dysfunctions of prefrontal cortex can impair inhibitory controls of ADHD patients, resulting in their impulsive behaviors. Researchers also find that rats with lesions in the orbitofrontal cortex show deficits in the reversal learning of attentional set-shifting task (ASST), a behavioral test frequently used in human studies to asses the inhibition system. However, the role of orbitofrontal dopamine system in the mechanism responsible for the dysfunctions of inhibitory controls in ADHD patients and animal models remains unknown. In the present study, we manipulated orbitofrontal dopamine activities of spontaneously hypertensive rats (SHR), a widely used ADHD animal model, through intra-peritoneal injection of methylphenidate (MPH) and central infusion of haloperidol, and observed their performances in ASST. The results show that juvenile SHRs learned slower than Wistar controls in the first and second reversal learnings of ASST. The deficits could be removed by intra-peritoneal injections of MPH. Furthermore, central infusions of haloperidol in the orbitofrontal cortex blocked the effects of MPH. In conclusions, dopamine activity in orbitofrontal cortex might play a crucial role in the neural mechanism of reversal learning deficits in this animal model of ADHD.

  5. Unsupervised learning of generative and discriminative weights encoding elementary image components in a predictive coding model of cortical function.

    Science.gov (United States)

    Spratling, M W

    2012-01-01

    A method is presented for learning the reciprocal feedforward and feedback connections required by the predictive coding model of cortical function. When this method is used, feedforward and feedback connections are learned simultaneously and independently in a biologically plausible manner. The performance of the proposed algorithm is evaluated by applying it to learning the elementary components of artificial and natural images. For artificial images, the bars problem is employed, and the proposed algorithm is shown to produce state-of-the-art performance on this task. For natural images, components resembling Gabor functions are learned in the first processing stage, and neurons responsive to corners are learned in the second processing stage. The properties of these learned representations are in good agreement with neurophysiological data from V1 and V2. The proposed algorithm demonstrates for the first time that a single computational theory can explain the formation of cortical RFs and also the response properties of cortical neurons once those RFs have been learned.

  6. Context Effects in a Temporal Discrimination Task: Further Tests of the Scalar Expectancy Theory and Learning-to-Time Models

    Science.gov (United States)

    Arantes, Joana; Machado, Armando

    2008-01-01

    Pigeons were trained on two temporal bisection tasks, which alternated every two sessions. In the first task, they learned to choose a red key after a 1-s signal and a green key after a 4-s signal; in the second task, they learned to choose a blue key after a 4-s signal and a yellow key after a 16-s signal. Then the pigeons were exposed to a…

  7. Using machine learning to classify image features from canine pelvic radiographs: evaluation of partial least squares discriminant analysis and artificial neural network models.

    Science.gov (United States)

    McEvoy, Fintan J; Amigo, José M

    2013-01-01

    As the number of images per study increases in the field of veterinary radiology, there is a growing need for computer-assisted diagnosis techniques. The purpose of this study was to evaluate two machine learning statistical models for automatically identifying image regions that contain the canine hip joint on ventrodorsal pelvis radiographs. A training set of images (120 of the hip and 80 from other regions) was used to train a linear partial least squares discriminant analysis (PLS-DA) model and a nonlinear artificial neural network (ANN) model to classify hip images. Performance of the models was assessed using a separate test image set (36 containing hips and 20 from other areas). Partial least squares discriminant analysis model achieved a classification error, sensitivity, and specificity of 6.7%, 100%, and 89%, respectively. The corresponding values for the ANN model were 8.9%, 86%, and 100%. Findings indicated that statistical classification of veterinary images is feasible and has the potential for grouping and classifying images or image features, especially when a large number of well-classified images are available for model training. © 2012 Veterinary Radiology & Ultrasound.

  8. Racial stereotypes impair flexibility of emotional learning.

    Science.gov (United States)

    Dunsmoor, Joseph E; Kubota, Jennifer T; Li, Jian; Coelho, Cesar A O; Phelps, Elizabeth A

    2016-09-01

    Flexibility of associative learning can be revealed by establishing and then reversing cue-outcome discriminations. Here, we used functional MRI to examine whether neurobehavioral correlates of reversal-learning are impaired in White and Asian volunteers when initial learning involves fear-conditioning to a racial out-group. For one group, the picture of a Black male was initially paired with shock (threat) and a White male was unpaired (safe). For another group, the White male was a threat and the Black male was safe. These associations reversed midway through the task. Both groups initially discriminated threat from safety, as expressed through skin conductance responses (SCR) and activity in the insula, thalamus, midbrain and striatum. After reversal, the group initially conditioned to a Black male exhibited impaired reversal of SCRs to the new threat stimulus (White male), and impaired reversals in the striatum, anterior cingulate cortex, midbrain and thalamus. In contrast, the group initially conditioned to a White male showed successful reversal of SCRs and successful reversal in these brain regions toward the new threat. These findings provide new evidence that an aversive experience with a racial out-group member impairs the ability to flexibly and appropriately adjust fear expression towards a new threat in the environment.

  9. Distinct contributions of lateral orbito-frontal cortex, striatum, and fronto-parietal network regions for rule encoding and control of memory-based implementation during instructed reversal learning.

    Science.gov (United States)

    Ruge, Hannes; Wolfensteller, Uta

    2016-01-15

    A key element of behavioral flexibility is to quickly learn to modify or reverse previously acquired stimulus-response associations. Such reversal learning (RL) can either be driven by feedback or by explicit instruction, informing either retrospectively or prospectively about the changed response requirements. Neuroimaging studies have thus far exclusively focused either on feedback-driven RL or on instructed initial learning of novel rules. The present study examined the neural basis of instructed RL as compared to instructed initial learning, separately assessing reversal-related instruction-based encoding processes and reversal-related control processes required for implementing reversed rules under competition from the initially learned rules. We found that instructed RL is partly supported by similar regions as feedback-driven RL, including lateral orbitofrontal cortex (lOFC) and anterior dorsal caudate. Encoding-related activation in both regions determined resilience against response competition during subsequent memory-based reversal implementation. Different from feedback-driven RL, instruction-based RL relied heavily on the generic fronto-parietal cognitive control network--not for encoding but for reversal-related control processes during memory-based implementation. These findings are consistent with a model of partly decoupled, yet interacting, systems of (i) symbolic rule representations that are instantaneously updated upon instruction and (ii) pragmatic representations of reward-associated S-R links mediating the enduring competition from initially learned rules.

  10. Can Southeast Asian Students Learn to Discriminate between English Phonemes More Quickly with the Aid of Music and Rhythm?

    Science.gov (United States)

    Karimer, Lisa

    A study of the effectiveness of music and rhythm used in classroom activities as a technique for developing short-term memory for phonological learning had as subjects 25 adult Cambodian, Lao, Hmong, and Vietnamese immigrants, students in a course in English as a second language. The subjects were given a pretest of their ability to distinguish…

  11. Research of Frequency Discriminator on Frequency Lock Loops

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Frequency lock loops (FLL) discriminating algorithms for direct-sequence spread-spectrum are discussed. The existing algorithms can't solve the problem of data bit reversal during one pre-detection integral period. And when the initial frequency offset is large, the frequency discriminator can't work normally. To solve these problems, a new FLL discriminating algorithm is introduced. The least-squares discriminator is used in this new algorithm. As the least-squares discriminator has a short process unit period, the corresponding frequency discriminating range is large. And the data bit reversal just influence one process unit period, so the least-squares discriminated result will not be affected. Compared with traditional frequency discriminator, the least-squares algorithm can effectively solve the problem of data bit reversal and can endure larger initial frequency offset.

  12. Loss of hippocampal neurogenesis, increased novelty-induced activity, decreased home cage activity, and impaired reversal learning one year after irradiation of the young mouse brain.

    Science.gov (United States)

    Kalm, Marie; Karlsson, Niklas; Nilsson, Marie K L; Blomgren, Klas

    2013-09-01

    Radiotherapy is a major cause of long-term complications in survivors of pediatric brain tumors. These complications include intellectual and memory impairments as well as perturbed growth and puberty. We investigated the long-term effects of a single 8 Gy irradiation dose to the brains of 14-day-old mice. Behavior was assessed one year after irradiation using IntelliCage and open field, followed by immunohistochemical investigation of proliferation and neurogenesis in the dentate gyrus of the hippocampus. We found a 61% reduction in proliferation and survival (BrdU incorporation 4 weeks prior to sacrifice), 99% decrease in neurogenesis (number of doublecortin-positive cells) and gliosis (12% higher astrocyte density) one year following irradiation. Irradiated animals displayed increased activity in a novel environment but decreased activity in their home cage. Place learning in the IntelliCage was unaffected by irradiation but reversal learning was impaired. Irradiated animals persevered in visiting previously correct corners to a higher extent compared to control animals. Hence, despite the virtual absence of neurogenesis in these old mice, spatial learning could take place. Reversal learning however, where a previous memory was replaced with a new one, was partly impaired. This model is useful to study the so called late effects of radiotherapy to the young brain and to evaluate possible interventions.

  13. Orbitofrontal cortex volume in area 11/13 predicts reward devaluation, but not reversal learning performance, in young and aged monkeys.

    Science.gov (United States)

    Burke, Sara N; Thome, Alex; Plange, Kojo; Engle, James R; Trouard, Theodore P; Gothard, Katalin M; Barnes, Carol A

    2014-07-23

    The orbitofrontal cortex (OFC) and amygdala are both necessary for decisions based on expected outcomes. Although behavioral and imaging data suggest that these brain regions are affected by advanced age, the extent to which aging alters appetitive processes coordinated by the OFC and the amygdala is unknown. In the current experiment, young and aged bonnet macaques were trained on OFC- and amygdala-dependent tasks that test the degree to which response selection is guided by reward value and can be adapted when expected outcomes change. To assess whether the structural integrity of these regions varies with levels of performance on reward devaluation and object reversal tasks, volumes of areas 11/13 and 14 of the OFC, central/medial (CM), and basolateral (BL) nuclei of the amygdala were determined from high-resolution anatomical MRIs. With age, there were significant reductions in OFC, but not CM and BL, volume. Moreover, the aged monkeys showed impairments in the ability to associate an object with a higher value reward, and to reverse a previously learned association. Interestingly, greater OFC volume of area 11/13, but not 14, was significantly correlated with an animal's ability to anticipate the reward outcome associated with an object, and smaller BL volume was predictive of an animal's tendency to choose a higher value reward, but volume of neither region correlated with reversal learning. Together, these data indicate that OFC volume has an impact on monkeys' ability to guide choice behavior based on reward value but does not impact ability to reverse a previously learned association.

  14. The effects of incidentally learned temporal and spatial predictability on response times and visual fixations during target detection and discrimination.

    Directory of Open Access Journals (Sweden)

    Melissa R Beck

    Full Text Available Responses are quicker to predictable stimuli than if the time and place of appearance is uncertain. Studies that manipulate target predictability often involve overt cues to speed up response times. However, less is known about whether individuals will exhibit faster response times when target predictability is embedded within the inter-trial relationships. The current research examined the combined effects of spatial and temporal target predictability on reaction time (RT and allocation of overt attention in a sustained attention task. Participants responded as quickly as possible to stimuli while their RT and eye movements were measured. Target temporal and spatial predictability were manipulated by altering the number of: 1 different time intervals between a response and the next target; and 2 possible spatial locations of the target. The effects of target predictability on target detection (Experiment 1 and target discrimination (Experiment 2 were tested. For both experiments, shorter RTs as target predictability increased across both space and time were found. In addition, the influences of spatial and temporal target predictability on RT and the overt allocation of attention were task dependent; suggesting that effective orienting of attention relies on both spatial and temporal predictability. These results indicate that stimulus predictability can be increased without overt cues and detected purely through inter-trial relationships over the course of repeated stimulus presentations.

  15. The effects of incidentally learned temporal and spatial predictability on response times and visual fixations during target detection and discrimination.

    Science.gov (United States)

    Beck, Melissa R; Hong, S Lee; van Lamsweerde, Amanda E; Ericson, Justin M

    2014-01-01

    Responses are quicker to predictable stimuli than if the time and place of appearance is uncertain. Studies that manipulate target predictability often involve overt cues to speed up response times. However, less is known about whether individuals will exhibit faster response times when target predictability is embedded within the inter-trial relationships. The current research examined the combined effects of spatial and temporal target predictability on reaction time (RT) and allocation of overt attention in a sustained attention task. Participants responded as quickly as possible to stimuli while their RT and eye movements were measured. Target temporal and spatial predictability were manipulated by altering the number of: 1) different time intervals between a response and the next target; and 2) possible spatial locations of the target. The effects of target predictability on target detection (Experiment 1) and target discrimination (Experiment 2) were tested. For both experiments, shorter RTs as target predictability increased across both space and time were found. In addition, the influences of spatial and temporal target predictability on RT and the overt allocation of attention were task dependent; suggesting that effective orienting of attention relies on both spatial and temporal predictability. These results indicate that stimulus predictability can be increased without overt cues and detected purely through inter-trial relationships over the course of repeated stimulus presentations.

  16. Neural responses in songbird forebrain reflect learning rates, acquired salience, and stimulus novelty after auditory discrimination training.

    Science.gov (United States)

    Bell, Brittany A; Phan, Mimi L; Vicario, David S

    2015-03-01

    How do social interactions form and modulate the neural representations of specific complex signals? This question can be addressed in the songbird auditory system. Like humans, songbirds learn to vocalize by imitating tutors heard during development. These learned vocalizations are important in reproductive and social interactions and in individual recognition. As a model for the social reinforcement of particular songs, male zebra finches were trained to peck for a food reward in response to one song stimulus (GO) and to withhold responding for another (NoGO). After performance reached criterion, single and multiunit neural responses to both trained and novel stimuli were obtained from multiple electrodes inserted bilaterally into two songbird auditory processing areas [caudomedial mesopallium (CMM) and caudomedial nidopallium (NCM)] of awake, restrained birds. Neurons in these areas undergo stimulus-specific adaptation to repeated song stimuli, and responses to familiar stimuli adapt more slowly than to novel stimuli. The results show that auditory responses differed in NCM and CMM for trained (GO and NoGO) stimuli vs. novel song stimuli. When subjects were grouped by the number of training days required to reach criterion, fast learners showed larger neural responses and faster stimulus-specific adaptation to all stimuli than slow learners in both areas. Furthermore, responses in NCM of fast learners were more strongly left-lateralized than in slow learners. Thus auditory responses in these sensory areas not only encode stimulus familiarity, but also reflect behavioral reinforcement in our paradigm, and can potentially be modulated by social interactions.

  17. Reverse Logistics

    OpenAIRE

    Kulikova, Olga

    2016-01-01

    This thesis was focused on the analysis of the concept of reverse logistics and actual reverse processes which are implemented in mining industry and finding solutions for the optimization of reverse logistics in this sphere. The objective of this paper was the assessment of the development of reverse logistics in mining industry on the example of potash production. The theoretical part was based on reverse logistics and mining waste related literature and provided foundations for further...

  18. Medical students' perception of lesbian, gay, bisexual, and transgender (LGBT) discrimination in their learning environment and their self-reported comfort level for caring for LGBT patients: a survey study.

    Science.gov (United States)

    Nama, Nassr; MacPherson, Paul; Sampson, Margaret; McMillan, Hugh J

    2017-01-01

    Historically, medical students who are lesbian, gay, bisexual or transgendered (LGBT) report higher rates of social stress, depression, and anxiety, while LGBT patients have reported discrimination and poorer access to healthcare. The objectives of this study were: (1) to assess if medical students have perceived discrimination in their learning environment and; (2) to determine self-reported comfort level for caring for LGBT patients. Medical students at the University of Ottawa (N = 671) were contacted via email and invited to complete a confidential web-based survey. Response rate was 15.4% (103/671). This included 66 cis-gender heterosexuals (64.1%) and 37 LGBT students (35.9%). Anti-LGBT discrimination had been witnessed by 14.6% and heterosexism by 31.1% of respondents. Anti-LGBT discrimination most often originated from fellow medical students. Respondents who self-identified as LGBT were more likely to have perceived heterosexism (favoring opposite-sex relationships) (OR = 8.2, p LGBT discrimination (OR = 6.6, p = 0.002). While half of LGBT students shared their status with all classmates (51.4%), they were more likely to conceal this from staff physicians (OR = 27.2, p = 0.002). Almost half of medical students (41.7%) reported anti-LGBT jokes, rumors, and/or bullying by fellow medical students and/or other members of the healthcare team. Still, most respondents indicated that they felt comfortable with and capable of providing medical care to LGBT patients (≥83.5%), and were interested in further education around LGBT health issues (84.5%). Anti-LGBT discrimination and heterosexism are noted by medical students, indicating a suboptimal learning environment for LGBT students. Nonetheless, students report a high level of comfort and confidence providing health care to LGBT patients.

  19. Lifelong disturbance of serotonin transporter functioning results in fear learning deficits : Reversal by blockade of CRF1 receptors

    NARCIS (Netherlands)

    Bijlsma, Elisabeth Y; Hendriksen, Hendrikus; Baas, Johanna M P; Millan, Mark J; Groenink, Lucianne

    2015-01-01

    The inability to associate aversive events with relevant cues (i.e. fear learning) may lead to maladaptive anxiety. To further study the role of the serotonin transporter (SERT) in fear learning, classical fear conditioning was studied in SERT knockout rats (SERT(-/-)) using fear potentiation of the

  20. Lifelong disturbance of serotonin transporter functioning results in fear learning deficits : Reversal by blockade of CRF1 receptors

    NARCIS (Netherlands)

    Bijlsma, Elisabeth Y; Hendriksen, Hendrikus; Baas, Johanna M P; Millan, Mark J; Groenink, Lucianne

    2015-01-01

    The inability to associate aversive events with relevant cues (i.e. fear learning) may lead to maladaptive anxiety. To further study the role of the serotonin transporter (SERT) in fear learning, classical fear conditioning was studied in SERT knockout rats (SERT(-/-)) using fear potentiation of the

  1. Outcome-Specific Transfer between Predictive and Instrumental Learning Is Unaffected by Extinction but Reversed by Counterconditioning in Human Participants

    Science.gov (United States)

    Rosas, Juan M.; Paredes-Olay, Maria C.; Garcia-Gutierrez, Ana; Espinosa, Juan J.; Abad, Maria J. F.

    2010-01-01

    Three experiments were conducted to explore the effects of different interference treatments upon outcome-specific transfer from predictive learning to instrumental responding. A computer game was designed in which participants had to defend Andalusia from navy and air-force attacks. Participants learned the relationship between two instrumental…

  2. Social discrimination of cage-mates and non-cage-mates by rats.

    Science.gov (United States)

    Jones, Samantha; Burman, Oliver; Mendl, Michael

    2014-07-01

    The ability to discriminate between group-mates and non-group-mates likely underpins the occurrence of affiliative and aggressive behaviour towards 'in-group' and 'out-group' individuals. Here we present two experiments aimed at testing the ability of rats (Rattus norvegicus) to discriminate between cage-mate (CM: animals residing in the subject's home cage) and non-cage-mate (NCM) conspecifics. In experiment 1, rats were trained to discriminate between different exemplars of CM and NCM using a lever pressing task employing symmetrical reinforcement. Subjects did not reach performance criterion, but they did show some evidence of discrimination between the two types of stimuli. In experiment 2, we employed a digging task to determine if rats can discriminate between odour cues from CM and NCM presented simultaneously on two sand-filled bowls. Subjects reached performance criterion on the first pair of odours, and on three more different pairs of CM and NCM odours. The results of a reversal task, using a fifth pair of odours, indicate that the rats were using a common factor to discriminate between social cues from CM and NCM conspecifics, rather than learning each pair independently. Possible candidates include a group-specific odour cue, or the development of a CM/NCM category concept. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Discrimination in lexical decision

    Science.gov (United States)

    Feldman, Laurie Beth; Ramscar, Michael; Hendrix, Peter; Baayen, R. Harald

    2017-01-01

    In this study we present a novel set of discrimination-based indicators of language processing derived from Naive Discriminative Learning (ndl) theory. We compare the effectiveness of these new measures with classical lexical-distributional measures—in particular, frequency counts and form similarity measures—to predict lexical decision latencies when a complete morphological segmentation of masked primes is or is not possible. Data derive from a re-analysis of a large subset of decision latencies from the English Lexicon Project, as well as from the results of two new masked priming studies. Results demonstrate the superiority of discrimination-based predictors over lexical-distributional predictors alone, across both the simple and primed lexical decision tasks. Comparable priming after masked corner and cornea type primes, across two experiments, fails to support early obligatory segmentation into morphemes as predicted by the morpho-orthographic account of reading. Results fit well with ndl theory, which, in conformity with Word and Paradigm theory, rejects the morpheme as a relevant unit of analysis. Furthermore, results indicate that readers with greater spelling proficiency and larger vocabularies make better use of orthographic priors and handle lexical competition more efficiently. PMID:28235015

  4. DNA targeting of rhinal cortex D2 receptor protein reversibly blocks learning of cues that predict reward.

    Science.gov (United States)

    Liu, Zheng; Richmond, Barry J; Murray, Elisabeth A; Saunders, Richard C; Steenrod, Sara; Stubblefield, Barbara K; Montague, Deidra M; Ginns, Edward I

    2004-08-17

    When schedules of several operant trials must be successfully completed to obtain a reward, monkeys quickly learn to adjust their behavioral performance by using visual cues that signal how many trials have been completed and how many remain in the current schedule. Bilateral rhinal (perirhinal and entorhinal) cortex ablations irreversibly prevent this learning. Here, we apply a recombinant DNA technique to investigate the role of dopamine D2 receptor in rhinal cortex for this type of learning. Rhinal cortex was injected with a DNA construct that significantly decreased D2 receptor ligand binding and temporarily produced the same profound learning deficit seen after ablation. However, unlike after ablation, the D2 receptor-targeted, DNA-treated monkeys recovered cue-related learning after 11-19 weeks. Injecting a DNA construct that decreased N-methyl-d-aspartate but not D2 receptor ligand binding did not interfere with learning associations between the cues and the schedules. A second D2 receptor-targeted DNA treatment administered after either recovery from a first D2 receptor-targeted DNA treatment (one monkey), after N-methyl-d-aspartate receptor-targeted DNA treatment (two monkeys), or after a vector control treatment (one monkey) also induced a learning deficit of similar duration. These results suggest that the D2 receptor in primate rhinal cortex is essential for learning to relate the visual cues to the schedules. The specificity of the receptor manipulation reported here suggests that this approach could be generalized in this or other brain pathways to relate molecular mechanisms to cognitive functions.

  5. Price Discrimination and Resale: A Classroom Experiment

    Science.gov (United States)

    Basuchoudhary, Atin; Metcalf, Christopher; Pommerenke, Kai; Reiley, David; Rojas, Christian; Rostek, Marzena; Stodder, James

    2008-01-01

    The authors present a classroom experiment designed to illustrate key concepts of third-degree price discrimination. By participating as buyers and sellers, students actively learn (1) how group pricing differs from uniform pricing, (2) how resale between buyers limits a seller's ability to price discriminate, and (3) how preventing price…

  6. Pattern recognition in bees : orientation discrimination

    NARCIS (Netherlands)

    Hateren, J.H. van; Srinivasan, M.V.; Wait, P.B.

    1990-01-01

    Honey bees (Apis mellifera, worker) were trained to discriminate between two random gratings oriented perpendicularly to each other. This task was quickly learned with vertical, horizontal, and oblique gratings. After being trained on perpendicularly-oriented random gratings, bees could discriminate

  7. Color Invariant SURF in Discriminative Object Tracking

    NARCIS (Netherlands)

    Chu, D.M.; Smeulders, A.W.M.

    2012-01-01

    Tracking can be seen as an online learning problem, where the focus is on discriminating object from background. From this point of view, features play a key role as the tracking accuracy depends on how well the feature distinguish object and background. Current discriminative trackers use tradition

  8. Color Invariant SURF in Discriminative Object Tracking

    NARCIS (Netherlands)

    D.M. Chu; A.W.M. Smeulders

    2010-01-01

    Tracking can be seen as an online learning problem, where the focus is on discriminating object from background. From this point of view, features play a key role as the tracking accuracy depends on how well the feature distinguish object and background. Current discriminative trackers use tradition

  9. Pattern recognition in bees : orientation discrimination

    NARCIS (Netherlands)

    Hateren, J.H. van; Srinivasan, M.V.; Wait, P.B.

    1990-01-01

    Honey bees (Apis mellifera, worker) were trained to discriminate between two random gratings oriented perpendicularly to each other. This task was quickly learned with vertical, horizontal, and oblique gratings. After being trained on perpendicularly-oriented random gratings, bees could discriminate

  10. Establishing a probabilistic reversal learning test in mice: evidence for the processes mediating reward-stay and punishment-shift behaviour and for their modulation by serotonin.

    Science.gov (United States)

    Ineichen, Christian; Sigrist, Hannes; Spinelli, Simona; Lesch, Klaus-Peter; Sautter, Eva; Seifritz, Erich; Pryce, Christopher R

    2012-11-01

    Valid animal models of psychopathology need to include behavioural readouts informed by human findings. In the probabilistic reversal learning (PRL) task, human subjects are confronted with serial reversal of the contingency between two operant stimuli and reward/punishment and, superimposed on this, a low probability (0.2) of punished correct responses/rewarded incorrect responses. In depression, reward-stay and reversals completed are unaffected but response-shift following punished correct response trials, referred to as negative feedback sensitivity (NFS), is increased. The aims of this study were to: establish an operant spatial PRL test appropriate for mice; obtain evidence for the processes mediating reward-stay and punishment-shift responding; and assess effects thereon of genetically- and pharmacologically-altered serotonin (5-HT) function. The study was conducted with wildtype (WT) and heterozygous mutant (HET) mice from a 5-HT transporter (5-HTT) null mutant strain. Mice were mildly food deprived and reward was sugar pellet and punishment was 5-s time out. Mice exhibited high motivation and adaptive reversal performance. Increased probability of punished correct response (PCR) trials per session (p = 0.1, 0.2 or 0.3) led to monotonic decrease in reward-stay and reversals completed, suggesting accurate reward prediction. NFS differed from chance-level at p PCR = 0.1, suggesting accurate punishment prediction, whereas NFS was at chance-level at p = 0.2-0.3. At p PCR = 0.1, HET mice exhibited lower NFS than WT mice. The 5-HTT blocker escitalopram was studied acutely at p PCR = 0.2: a low dose (0.5-1.5 mg/kg) resulted in decreased NFS, increased reward-stay and increased reversals completed, and similarly in WT and HET mice. This study demonstrates that testing PRL in mice can provide evidence on the regulation of reward and punishment processing that is, albeit within certain limits, of relevance to human emotional-cognitive processing, its dysfunction and

  11. Discriminant Kernel Assignment for Image Coding.

    Science.gov (United States)

    Deng, Yue; Zhao, Yanyu; Ren, Zhiquan; Kong, Youyong; Bao, Feng; Dai, Qionghai

    2017-06-01

    This paper proposes discriminant kernel assignment (DKA) in the bag-of-features framework for image representation. DKA slightly modifies existing kernel assignment to learn width-variant Gaussian kernel functions to perform discriminant local feature assignment. When directly applying gradient-descent method to solve DKA, the optimization may contain multiple time-consuming reassignment implementations in iterations. Accordingly, we introduce a more practical way to locally linearize the DKA objective and the difficult task is cast as a sequence of easier ones. Since DKA only focuses on the feature assignment part, it seamlessly collaborates with other discriminative learning approaches, e.g., discriminant dictionary learning or multiple kernel learning, for even better performances. Experimental evaluations on multiple benchmark datasets verify that DKA outperforms other image assignment approaches and exhibits significant efficiency in feature coding.

  12. Multi-modal, Multi-measure, and Multi-class Discrimination of ADHD with Hierarchical Feature Extraction and Extreme Learning Machine Using Structural and Functional Brain MRI.

    Science.gov (United States)

    Qureshi, Muhammad Naveed Iqbal; Oh, Jooyoung; Min, Beomjun; Jo, Hang Joon; Lee, Boreom

    2017-01-01

    Structural and functional MRI unveil many hidden properties of the human brain. We performed this multi-class classification study on selected subjects from the publically available attention deficit hyperactivity disorder ADHD-200 dataset of patients and healthy children. The dataset has three groups, namely, ADHD inattentive, ADHD combined, and typically developing. We calculated the global averaged functional connectivity maps across the whole cortex to extract anatomical atlas parcellation based features from the resting-state fMRI (rs-fMRI) data and cortical parcellation based features from the structural MRI (sMRI) data. In addition, the preprocessed image volumes from both of these modalities followed an ANOVA analysis separately using all the voxels. This study utilized the average measure from the most significant regions acquired from ANOVA as features for classification in addition to the multi-modal and multi-measure features of structural and functional MRI data. We extracted most discriminative features by hierarchical sparse feature elimination and selection algorithm. These features include cortical thickness, image intensity, volume, cortical thickness standard deviation, surface area, and ANOVA based features respectively. An extreme learning machine performed both the binary and multi-class classifications in comparison with support vector machines. This article reports prediction accuracy of both unimodal and multi-modal features from test data. We achieved 76.190% (p multi-class settings as well as 92.857% (p multi-modal group analysis approach with multi-measure features may improve the accuracy of the ADHD differential diagnosis.

  13. Multimodal Discrimination of Schizophrenia Using Hybrid Weighted Feature Concatenation of Brain Functional Connectivity and Anatomical Features with an Extreme Learning Machine

    Directory of Open Access Journals (Sweden)

    Muhammad Naveed Iqbal Qureshi

    2017-09-01

    Full Text Available Multimodal features of structural and functional magnetic resonance imaging (MRI of the human brain can assist in the diagnosis of schizophrenia. We performed a classification study on age, sex, and handedness-matched subjects. The dataset we used is publicly available from the Center for Biomedical Research Excellence (COBRE and it consists of two groups: patients with schizophrenia and healthy controls. We performed an independent component analysis and calculated global averaged functional connectivity-based features from the resting-state functional MRI data for all the cortical and subcortical anatomical parcellation. Cortical thickness along with standard deviation, surface area, volume, curvature, white matter volume, and intensity measures from the cortical parcellation, as well as volume and intensity from sub-cortical parcellation and overall volume of cortex features were extracted from the structural MRI data. A novel hybrid weighted feature concatenation method was used to acquire maximal 99.29% (P < 0.0001 accuracy which preserves high discriminatory power through the weight of the individual feature type. The classification was performed by an extreme learning machine, and its efficiency was compared to linear and non-linear (radial basis function support vector machines, linear discriminant analysis, and random forest bagged tree ensemble algorithms. This article reports the predictive accuracy of both unimodal and multimodal features after 10-by-10-fold nested cross-validation. A permutation test followed the classification experiment to assess the statistical significance of the classification results. It was concluded that, from a clinical perspective, this feature concatenation approach may assist the clinicians in schizophrenia diagnosis.

  14. A multiplicative reinforcement learning model capturing learning dynamics and interindividual variability in mice.

    Science.gov (United States)

    Bathellier, Brice; Tee, Sui Poh; Hrovat, Christina; Rumpel, Simon

    2013-12-03

    Both in humans and in animals, different individuals may learn the same task with strikingly different speeds; however, the sources of this variability remain elusive. In standard learning models, interindividual variability is often explained by variations of the learning rate, a parameter indicating how much synapses are updated on each learning event. Here, we theoretically show that the initial connectivity between the neurons involved in learning a task is also a strong determinant of how quickly the task is learned, provided that connections are updated in a multiplicative manner. To experimentally test this idea, we trained mice to perform an auditory Go/NoGo discrimination task followed by a reversal to compare learning speed when starting from naive or already trained synaptic connections. All mice learned the initial task, but often displayed sigmoid-like learning curves, with a variable delay period followed by a steep increase in performance, as often observed in operant conditioning. For all mice, learning was much faster in the subsequent reversal training. An accurate fit of all learning curves could be obtained with a reinforcement learning model endowed with a multiplicative learning rule, but not with an additive rule. Surprisingly, the multiplicative model could explain a large fraction of the interindividual variability by variations in the initial synaptic weights. Altogether, these results demonstrate the power of multiplicative learning rules to account for the full dynamics of biological learning and suggest an important role of initial wiring in the brain for predispositions to different tasks.

  15. Intra-individual gait patterns across different time-scales as revealed by means of a supervised learning model using kernel-based discriminant regression.

    Science.gov (United States)

    Horst, Fabian; Eekhoff, Alexander; Newell, Karl M; Schöllhorn, Wolfgang I

    2017-01-01

    Traditionally, gait analysis has been centered on the idea of average behavior and normality. On one hand, clinical diagnoses and therapeutic interventions typically assume that average gait patterns remain constant over time. On the other hand, it is well known that all our movements are accompanied by a certain amount of variability, which does not allow us to make two identical steps. The purpose of this study was to examine changes in the intra-individual gait patterns across different time-scales (i.e., tens-of-mins, tens-of-hours). Nine healthy subjects performed 15 gait trials at a self-selected speed on 6 sessions within one day (duration between two subsequent sessions from 10 to 90 mins). For each trial, time-continuous ground reaction forces and lower body joint angles were measured. A supervised learning model using a kernel-based discriminant regression was applied for classifying sessions within individual gait patterns. Discernable characteristics of intra-individual gait patterns could be distinguished between repeated sessions by classification rates of 67.8 ± 8.8% and 86.3 ± 7.9% for the six-session-classification of ground reaction forces and lower body joint angles, respectively. Furthermore, the one-on-one-classification showed that increasing classification rates go along with increasing time durations between two sessions and indicate that changes of gait patterns appear at different time-scales. Discernable characteristics between repeated sessions indicate continuous intrinsic changes in intra-individual gait patterns and suggest a predominant role of deterministic processes in human motor control and learning. Natural changes of gait patterns without any externally induced injury or intervention may reflect continuous adaptations of the motor system over several time-scales. Accordingly, the modelling of walking by means of average gait patterns that are assumed to be near constant over time needs to be reconsidered in the context of

  16. Fighting discrimination.

    Science.gov (United States)

    Wientjens, Wim; Cairns, Douglas

    2012-10-01

    In the fight against discrimination, the IDF launched the first ever International Charter of Rights and Responsibilities of People with Diabetes in 2011: a balance between rights and duties to optimize health and quality of life, to enable as normal a life as possible and to reduce/eliminate the barriers which deny realization of full potential as members of society. It is extremely frustrating to suffer blanket bans and many examples exist, including insurance, driving licenses, getting a job, keeping a job and family affairs. In this article, an example is given of how pilots with insulin treated diabetes are allowed to fly by taking the responsibility of using special blood glucose monitoring protocols. At this time the systems in the countries allowing flying for pilots with insulin treated diabetes are applauded, particularly the USA for private flying, and Canada for commercial flying. Encouraging developments may be underway in the UK for commercial flying and, if this materializes, could be used as an example for other aviation authorities to help adopt similar protocols. However, new restrictions implemented by the new European Aviation Authority take existing privileges away for National Private Pilot Licence holders with insulin treated diabetes in the UK.

  17. Selective activation of M4 muscarinic acetylcholine receptors reverses MK-801-induced behavioral impairments and enhances associative learning in rodents

    DEFF Research Database (Denmark)

    Bubser, Michael; Bridges, Thomas M; Dencker, Ditte;

    2014-01-01

    an antipsychotic drug-like profile in rodents after amphetamine challenge. Previous studies suggest that enhanced cholinergic activity may also improve cognitive function and reverse deficits observed with reduced signaling through the N-methyl-d-aspartate subtype of the glutamate receptor (NMDAR) in the central...... PAMs, enabling a more extensive characterization of M4 actions in rodent models. We used VU0467154 to test the hypothesis that selective potentiation of M4 receptor signaling could ameliorate the behavioral, cognitive, and neurochemical impairments induced by the noncompetitive NMDAR antagonist MK-801...

  18. Discriminant forest classification method and system

    Science.gov (United States)

    Chen, Barry Y.; Hanley, William G.; Lemmond, Tracy D.; Hiller, Lawrence J.; Knapp, David A.; Mugge, Marshall J.

    2012-11-06

    A hybrid machine learning methodology and system for classification that combines classical random forest (RF) methodology with discriminant analysis (DA) techniques to provide enhanced classification capability. A DA technique which uses feature measurements of an object to predict its class membership, such as linear discriminant analysis (LDA) or Andersen-Bahadur linear discriminant technique (AB), is used to split the data at each node in each of its classification trees to train and grow the trees and the forest. When training is finished, a set of n DA-based decision trees of a discriminant forest is produced for use in predicting the classification of new samples of unknown class.

  19. Engineering Encounters: Reverse Engineering

    Science.gov (United States)

    McGowan, Veronica Cassone; Ventura, Marcia; Bell, Philip

    2017-01-01

    This column presents ideas and techniques to enhance your science teaching. This month's issue shares information on how students' everyday experiences can support science learning through engineering design. In this article, the authors outline a reverse-engineering model of instruction and describe one example of how it looked in our fifth-grade…

  20. Discrimination and Anti-discrimination in Denmark

    DEFF Research Database (Denmark)

    Olsen, Tore Vincents

    The purpose of this report is to describe and analyse Danish anti-discrimination legislation and the debate about discrimination in Denmark in order to identify present and future legal challenges. The main focus is the implementation of the EU anti-discrimination directives in Danish law...

  1. Discrimination and Anti-discrimination in Denmark

    DEFF Research Database (Denmark)

    Olsen, Tore Vincents

    The purpose of this report is to describe and analyse Danish anti-discrimination legislation and the debate about discrimination in Denmark in order to identify present and future legal challenges. The main focus is the implementation of the EU anti-discrimination directives in Danish law...

  2. Discriminative learning after uncontrollable shocks

    Directory of Open Access Journals (Sweden)

    Angelica Capelari

    2009-10-01

    Full Text Available O objetivo desse estudo foi investigar se estímulos aversivos não contingentes (incontroláveis produzem interferência em um processo de aprendizagem discriminativa reforçada positivamente. Vinte e quatro ratos foram distribuídos em três grupos (n=8 que diferiram entre si quanto ao tratamento recebido na primeira sessão: choques controláveis (C, incontroláveis (I ou nenhum choque (N. Posteriormente, todos foram submetidos a 10 sessões de treino discriminativo com reforço positivo, em esquema múltiplo-concorrente FR-6/Extinção. Os resultados do treino discriminativo mostraram que, na primeira sessão, a exposição prévia a choques produziu menor frequência de respostas, sendo esse efeito levemente mais acentuado no grupo I; na décima sessão, os grupos não diferiram entre si quanto à frequência de respostas e ao índice discriminativo, que ficou acima de 0,80. O efeito transitório do tratamento com choques incontroláveis, sem interferência a longo prazo no estabelecimento do controle de estímulos por reforçamento positivo, é contrário à generalidade do desamparo aprendido para contextos não aversivos.   Palavras-chave: desamparo aprendido; incontrolabilidade; controle de estímulos.

  3. Altered brain activation in a reversal learning task unmasks adaptive changes in cognitive control in writer's cramp

    Directory of Open Access Journals (Sweden)

    Kirsten E. Zeuner

    2016-01-01

    The Brodmann area 32 (BA32 is part of the dorsal anterior cingulate cortex (dACC that plays an important role in coordinating and integrating information to guide behavior and in reward-based learning. The dACC is connected with the basal ganglia-thalamo-loop modulated by dopaminergic signaling. This finding suggests disturbed integration of reinforcement history in decision making and implicate that the reward system might contribute to the pathogenesis in writer's cramp.

  4. Lifelong disturbance of serotonin transporter functioning results in fear learning deficits: Reversal by blockade of CRF1 receptors.

    Science.gov (United States)

    Bijlsma, Elisabeth Y; Hendriksen, Hendrikus; Baas, Johanna M P; Millan, Mark J; Groenink, Lucianne

    2015-10-01

    The inability to associate aversive events with relevant cues (i.e. fear learning) may lead to maladaptive anxiety. To further study the role of the serotonin transporter (SERT) in fear learning, classical fear conditioning was studied in SERT knockout rats (SERT(-/-)) using fear potentiation of the startle reflex. Next, fear acquisition and concomitant development of contextual conditioned fear were monitored during training. To differentiate between developmental and direct effects of reduced SERT functioning, effects of acute and chronic SSRI treatment were studied in adult rats. Considering the known interactions between serotonin and corticotropin-releasing factor (CRF), we studied the effect of the CRFR1 antagonist CP154,526 on behavioral changes observed and determined CRF1 receptor levels in SERT(-/-) rats. SERT(-/-) showed blunted fear potentiation and enhanced contextual fear, which resulted from a deficit in fear acquisition. Paroxetine treatment did not affect acquisition or expression of fear-potentiated startle, suggesting that disturbed fear learning in SERT(-/-) results from developmental changes and not from reduced SERT functioning. Although CRF1 receptor levels did not differ significantly between genotypes, CP154,526 treatment normalized both cue- and contextual fear in SERT(-/-) during acquisition, but not expression of fear-potentiated startle. The disrupted fear acquisition and concomitant increase in contextual conditioned fear-potentiated startle fear in SERT(-/-) resembles the associative learning deficit seen in patients with panic disorder and suggests that normal SERT functioning is crucial for the development of an adequate fear neuro-circuitry. Moreover, the normalization of fear acquisition by CP154,526 suggests a role for central CRF signaling in the generalization of fear.

  5. Validation and scopolamine-reversal of latent learning in the water maze utilizing a revised direct platform placement procedure.

    Science.gov (United States)

    Malin, David H; Schaar, Krystal L; Izygon, Jonathan J; Nghiem, Duyen M; Jabitta, Sikirat Y; Henceroth, Mallori M; Chang, Yu-Hsuan; Daggett, Jenny M; Ward, Christopher P

    2015-08-01

    The Morris water maze is routinely used to explore neurobiological mechanisms of working memory. Humans can often acquire working memory relevant to performing a task by mere sensory observation, without having to actually perform the task followed by reinforcement. This can be modeled in the water maze through direct placement of a rat on the escape platform so that it can observe the location, and then assessing the subject's performance in swimming back to the platform. However, direct placement procedures have hardly been studied for two decades, reflecting a controversy about whether direct placement resulted in sufficiently rapid and direct swims back to the platform. In the present study, utilizing revised training methods, a more comprehensive measure of trajectory directness, a more rigorous sham-trained control procedure and an optimal placement-test interval, rats swam almost directly back to the platform in under 4s, significantly more quickly and directly than sham-trained subjects. Muscarinic cholinergic mechanisms, which are inactivated by scopolamine, are essential to memory for standard learning paradigms in the water maze. This experiment determined whether this would also be true for latent learning. ANOVA revealed significant negative effects of scopolamine on both speed and accuracy of trajectory, as well as significant positive effects of direct placement training vs. sham-training. In a probe trial, placement-trained animals without scopolamine spent significantly more time and path length in the target quadrant than trained rats with scopolamine and sham-trained rats without scopolamine. Scopolamine impairments are likely due to effects on memory, since the same dose had little effect on performance with a visible platform. The revised direct placement model offers a means of further comparing the neural mechanisms of latent learning with those of standard instrumental learning.

  6. Touchscreen assays of learning, response inhibition, and motivation in the marmoset (Callithrix jacchus).

    Science.gov (United States)

    Kangas, Brian D; Bergman, Jack; Coyle, Joseph T

    2016-05-01

    Recent developments in precision gene editing have led to the emergence of the marmoset as an experimental subject of considerable interest and translational value. A better understanding of behavioral phenotypes of the common marmoset will inform the extent to which forthcoming transgenic mutants are cognitively intact. Therefore, additional information regarding their learning, inhibitory control, and motivational abilities is needed. The present studies used touchscreen-based repeated acquisition and discrimination reversal tasks to examine basic dimensions of learning and response inhibition. Marmosets were trained daily to respond to one of the two simultaneously presented novel stimuli. Subjects learned to discriminate the two stimuli (acquisition) and, subsequently, with the contingencies switched (reversal). In addition, progressive ratio performance was used to measure the effort expended to obtain a highly palatable reinforcer varying in magnitude and, thereby, provide an index of relative motivational value. Results indicate that rates of both acquisition and reversal of novel discriminations increased across successive sessions, but that rate of reversal learning remained slower than acquisition learning, i.e., more trials were needed for mastery. A positive correlation was observed between progressive ratio break point and reinforcement magnitude. These results closely replicate previous findings with squirrel monkeys, thus providing evidence of similarity in learning processes across nonhuman primate species. Moreover, these data provide key information about the normative phenotype of wild-type marmosets using three relevant behavioral endpoints.

  7. Reverse logistics

    NARCIS (Netherlands)

    M.P. de Brito (Marisa); S.D.P. Flapper; R. Dekker (Rommert)

    2002-01-01

    textabstractThis paper gives an overview of scientific literature that describes and discusses cases of reverse logistics activities in practice. Over sixty case studies are considered. Based on these studies we are able to indicate critical factors for the practice of reverse logistics. In addi

  8. Pioglitazone improves reversal learning and exerts mixed cerebrovascular effects in a mouse model of Alzheimer's disease with combined amyloid-β and cerebrovascular pathology.

    Directory of Open Access Journals (Sweden)

    Panayiota Papadopoulos

    Full Text Available Animal models of Alzheimer's disease (AD are invaluable in dissecting the pathogenic mechanisms and assessing the efficacy of potential new therapies. Here, we used the peroxisome proliferator-activated receptor gamma agonist pioglitazone in an attempt to rescue the pathogenic phenotype in adult (12 months and aged (>18 months bitransgenic A/T mice that overexpress a mutated human amyloid precursor protein (APPSwe,Ind and a constitutively active form of transforming growth factor-β1 (TGF-β1. A/T mice recapitulate the AD-related cognitive deficits, amyloid beta (Aβ and cerebrovascular pathologies, as well as the altered metabolic and vascular coupling responses to increased neuronal activity. Pioglitazone normalized neurometabolic and neurovascular coupling responses to sensory stimulation, and reduced cortical astroglial and hippocampal microglial activation in both age groups. Spatial learning and memory deficits in the Morris water maze were not rescued by pioglitazone, but reversal learning was improved in the adult cohort notwithstanding a progressing Aβ pathology. While pioglitazone preserved the constitutive nitric oxide synthesis in the vessel wall, it unexpectedly failed to restore cerebrovascular reactivity in A/T mice and even exacerbated the dilatory deficits. These data demonstrate pioglitazone's efficacy on selective AD hallmarks in a complex AD mouse model of comorbid amyloidosis and cerebrovascular pathology. They further suggest a potential benefit of pioglitazone in managing neuroinflammation, cerebral perfusion and glucose metabolism in AD patients devoid of cerebrovascular pathology.

  9. The Badness of Discrimination

    DEFF Research Database (Denmark)

    Lippert-Rasmussen, Kasper

    2006-01-01

    The most blatant forms of discrimination are morally outrageous and very obviously so; but the nature and boundaries of discrimination are more controversial, and it is not clear whether all forms of discrimination are morally bad; nor is it clear why objectionable cases of discrimination are bad....... In this paper I address these issues. First, I offer a taxonomy of discrimination. I then argue that discrimination is bad, when it is, because it harms people. Finally, I criticize a rival, disrespect-based account according to which discrimination is bad regardless of whether it causes harm....

  10. Socially-Tolerable Discrimination

    OpenAIRE

    J. Atsu Amegashie

    2008-01-01

    History is replete with overt discrimination of various forms. However, these forms of discrimination are not equally tolerable. For example, discrimination based on immutable or prohibitively unalterable characteristics such as race or gender is much less acceptable. Why? I develop a simple model of conflict which is driven by either racial (gender) discrimination or generational discrimination (i.e., young versus old). I show that there exist parameters of the model where racial (gender) di...

  11. TGF-β Signaling in Dopaminergic Neurons Regulates Dendritic Growth, Excitatory-Inhibitory Synaptic Balance, and Reversal Learning

    Directory of Open Access Journals (Sweden)

    Sarah X. Luo

    2016-12-01

    Full Text Available Neural circuits involving midbrain dopaminergic (DA neurons regulate reward and goal-directed behaviors. Although local GABAergic input is known to modulate DA circuits, the mechanism that controls excitatory/inhibitory synaptic balance in DA neurons remains unclear. Here, we show that DA neurons use autocrine transforming growth factor β (TGF-β signaling to promote the growth of axons and dendrites. Surprisingly, removing TGF-β type II receptor in DA neurons also disrupts the balance in TGF-β1 expression in DA neurons and neighboring GABAergic neurons, which increases inhibitory input, reduces excitatory synaptic input, and alters phasic firing patterns in DA neurons. Mice lacking TGF-β signaling in DA neurons are hyperactive and exhibit inflexibility in relinquishing learned behaviors and re-establishing new stimulus-reward associations. These results support a role for TGF-β in regulating the delicate balance of excitatory/inhibitory synaptic input in local microcircuits involving DA and GABAergic neurons and its potential contributions to neuropsychiatric disorders.

  12. A Developmental Study of Factors Influencing Discrimination Transfer

    Science.gov (United States)

    Cole, Michael

    1973-01-01

    Examines the importance of (1) dimensional characteristics of stimuli present in discrimination transfer tasks, (2) having contrasting stimuli presented simultaneously, and (3) subjects age. Subjects were rural Mexican youths, ages 4 to 10. Reversal and nonreversal type discrimination transfer problems were used in the study. (DP)

  13. Analysis of the Difficulty and Discrimination Indices of Multiple-Choice Questions According to Cognitive Levels in an Open and Distance Learning Context

    Science.gov (United States)

    Koçdar, Serpil; Karadag, Nejdet; Sahin, Murat Dogan

    2016-01-01

    This is a descriptive study which intends to determine whether the difficulty and discrimination indices of the multiple-choice questions show differences according to cognitive levels of the Bloom's Taxonomy, which are used in the exams of the courses in a business administration bachelor's degree program offered through open and distance…

  14. African American Students' Perceptions of Differential Treatment in Learning Environments: Examining the Moderating Role of Peer Support, Connection to Heritage, and Discrimination Efficacy

    Science.gov (United States)

    Brittian, Aerika S.; Gray, DeLeon L.

    2014-01-01

    This study examined the relationship between African American students' perceptions of differential treatment by teachers and educational outcomes, and the factors that promote these outcomes in the context of perceived discrimination, focusing on the protective value of youth's cultural heritage, as well as individual characteristics. The…

  15. Gender Discrimination in English

    Institute of Scientific and Technical Information of China (English)

    廖敏慧

    2014-01-01

    Gender discrimination in language is usually defined as discrimination based on sex, especially discrimination against women. With the rise of women’s liberation movement in the 1960s and 1970s, and the improvement of women’s social status in recent years, gender discrimination in English attracts more and more attention. Based on previous studies, this thesis first dis⁃cusses the manifestations of gender discrimination in English vocabulary and address terms, then analyzes the factors of gender dis⁃crimination in English from social and cultural perspectives, finally puts forward some methods that are good for avoiding or elim⁃inating gender discrimination in English.

  16. Earthquake-explosion discrimination using diffusion maps

    Science.gov (United States)

    Rabin, N.; Bregman, Y.; Lindenbaum, O.; Ben-Horin, Y.; Averbuch, A.

    2016-12-01

    Discrimination between earthquakes and explosions is an essential component of nuclear test monitoring and it is also important for maintaining the quality of earthquake catalogues. Currently used discrimination methods provide a partial solution to the problem. In this work, we apply advanced machine learning methods and in particular diffusion maps for modelling and discriminating between seismic signals. Diffusion maps enable us to construct a geometric representation that capture the intrinsic structure of the seismograms. The diffusion maps are applied after a pre-processing step, in which seismograms are converted to normalized sonograms. The constructed low-dimensional model is used for automatic earthquake-explosion discrimination of data that are collected in single seismic stations. We demonstrate our approach on a data set comprising seismic events from the Dead Sea area. The diffusion-based algorithm provides correct discrimination rate that is higher than 90 per cent.

  17. Antisense directed against PS-1 gene decreases brain oxidative markers in aged senescence accelerated mice (SAMP8) and reverses learning and memory impairment: a proteomics study.

    Science.gov (United States)

    Fiorini, Ada; Sultana, Rukhsana; Förster, Sarah; Perluigi, Marzia; Cenini, Giovanna; Cini, Chiara; Cai, Jian; Klein, Jon B; Farr, Susan A; Niehoff, Michael L; Morley, John E; Kumar, Vijaya B; Allan Butterfield, D

    2013-12-01

    Amyloid β-peptide (Aβ) plays a central role in the pathophysiology of Alzheimer's disease (AD) through the induction of oxidative stress. This peptide is produced by proteolytic cleavage of amyloid precursor protein (APP) by the action of β- and γ-secretases. Previous studies demonstrated that reduction of Aβ, using an antisense oligonucleotide (AO) directed against the Aβ region of APP, reduced oxidative stress-mediated damage and prevented or reverted cognitive deficits in senescence-accelerated prone mice (SAMP8), a useful animal model for investigating the events related to Aβ pathology and possibly to the early phase of AD. In the current study, aged SAMP8 were treated by AO directed against PS-1, a component of the γ-secretase complex, and tested for learning and memory in T-maze foot shock avoidance and novel object recognition. Brain tissue was collected to identify the decrease of oxidative stress and to evaluate the proteins that are differently expressed and oxidized after the reduction in free radical levels induced by Aβ. We used both expression proteomics and redox proteomics approaches. In brain of AO-treated mice a decrease of oxidative stress markers was found, and the proteins identified by proteomics as expressed differently or nitrated are involved in processes known to be impaired in AD. Our results suggest that the treatment with AO directed against PS-1 in old SAMP8 mice reverses learning and memory deficits and reduces Aβ-mediated oxidative stress with restoration to the normal condition and identifies possible pharmacological targets to combat this devastating dementing disease. Copyright © 2013 Elsevier Inc. All rights reserved.

  18. Reversal of learning deficits in hAPP transgenic mice carrying a mutation at Asp664: a role for early experience.

    Science.gov (United States)

    Zhang, Junli; Gorostiza, Olivia F; Tang, Huidong; Bredesen, Dale E; Galvan, Veronica

    2010-01-20

    In addition to the cleavages that generate amyloid-beta (Abeta), the Abeta-precursor protein (APP) is processed at Asp664, releasing a second toxic peptide (APP-C31). Transgenic mice otherwise identical to a well-characterized model of AD, PDAPP mice, but carrying a mutation that obliterates Asp664 show a reversal of AD-like deficits in memory and in non-cognitive components of behaviour in spite of accumulating high levels of Abeta. These results suggest that cleavage of APP at Asp664 plays a role in the generation of AD-like deficits, and that a major pathway of Abeta toxicity in vivo, or a pathway that crucially impinges on it, may depend on cleavage of APP at Asp664. Since young PDAPP(D664A) mice showed an akinetic phenotype when first required to swim, we trained a 3-month-old (mo) cohort to criterion (normal swimming), and briefly exposed it to the Morris water maze (MWM) environment prior to training at 7 mo, to avoid potentially confounding effects of the akinetic phenotype in MWM studies. Prior experience decreased floating in PDAPP(D664A) mice but not in PDAPP nor in non-Tg groups. While learning was restored in experienced PDAPP(D664A) mice, it was indistinguishable from both non-Tg as well as from PDAPP mice in naïve PDAPP(D664A) animals. Floating did not correlate with worse performance in naïve PDAPP(D664A) mice, suggesting that the contribution of prior experience to improved performance is related to its cognitive effects but not to non-cognitive components of behaviour. Our results suggest that early experience reduces the contribution of non-cognitive components of behaviour to performance, and may contribute to the restoration of learning at later ages in PDAPP(D664A) mice.

  19. REVERSE ENGINEERING AND ITS REALISTIC APPLICATIONS

    OpenAIRE

    Nikita Bakshi; Shruti Gujral

    2014-01-01

    Reverse-engineering is used for many purposes like as a learning tool, as a way to make compatible products that are cheaper than what is currently on the market. This paper discusses what is software, its type, reverse engineering, applications of reverse engineering and their tools.

  20. REVERSE ENGINEERING AND ITS REALISTIC APPLICATIONS

    Directory of Open Access Journals (Sweden)

    Nikita Bakshi

    2014-06-01

    Full Text Available Reverse-engineering is used for many purposes like as a learning tool, as a way to make compatible products that are cheaper than what is currently on the market. This paper discusses what is software, its type, reverse engineering, applications of reverse engineering and their tools.

  1. Unsupervised Linear Discriminant Analysis

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    An algorithm for unsupervised linear discriminant analysis was presented. Optimal unsupervised discriminant vectors are obtained through maximizing covariance of all samples and minimizing covariance of local k-nearest neighbor samples. The experimental results show our algorithm is effective.

  2. Airline Price Discrimination

    OpenAIRE

    Stacey, Brian

    2015-01-01

    Price discrimination enjoys a long history in the airline industry. Borenstein (1989) discusses price discrimination through frequent flyer programs from 1985 as related to the Piedmont-US Air merger, price discrimination strategies have grown in size and scope since then. From Saturday stay over requirements to varying costs based on time of purchase, the airline industry is uniquely situated to enjoy the fruits of price discrimination.

  3. Reversible Computing

    Science.gov (United States)

    1980-02-01

    will have been introduced. 9. Reversible celular autemata We shall assume the reader to have some familiarity with the concept of cel- lular...10003 Mr. Kin B. Thcmpson 1 copy Technical Director Information Systems Divisia.i Naval Research Laboratory (OP-91T) Technical Information Division

  4. Incremental Discriminant Analysis in Tensor Space

    Science.gov (United States)

    Chang, Liu; Weidong, Zhao; Tao, Yan; Qiang, Pu; Xiaodan, Du

    2015-01-01

    To study incremental machine learning in tensor space, this paper proposes incremental tensor discriminant analysis. The algorithm employs tensor representation to carry on discriminant analysis and combine incremental learning to alleviate the computational cost. This paper proves that the algorithm can be unified into the graph framework theoretically and analyzes the time and space complexity in detail. The experiments on facial image detection have shown that the algorithm not only achieves sound performance compared with other algorithms, but also reduces the computational issues apparently. PMID:26339229

  5. Operant conditioning and discrimination of alpha: some methodological limitations inherent in response-discrimination experiments.

    Science.gov (United States)

    Cott, A; Pavloski, R P; Black, A H

    1981-09-01

    Studies on the operant conditioning of central nervous system activity have produced results interpreted as demonstrating that responses, certain properties of responses, or response-produced stimuli can function as discriminative stimuli. It is assumed that the feedback stimulus in biofeedback makes the subject aware of the internal response and that by becoming aware of the response, the subject can acquire voluntary control over it. In this context, awareness is operationally defined as the ability to use the response as a discriminative stimulus. Since direct evidence for the assumed relationship between control and discrimination is lacking, an attempt was made to test the hypothesis that discrimination of a response automatically leads to control over that response. The discriminative stimuli were the presence and absence of occipital alpha electroencephalograph (EEG) activity. Data from two experiments are reported. The first study, employing naive subjects, was designed to answer the following questions: (a) Since pilot data indicated that subjects seemed to match their responses to the more probable type of trial, would increases in the probability of a correct response result when the probabilities of alpha and nonalpha trials were held near .50? (b) If correct responding does increase, would performance of these subjects in an alpha feedback task be enhanced relative to that of subjects not previously given discrimination training? and (c) If subjects could not learn the discrimination task, would feedback training enhance their performance in a subsequent discrimination task? Results from this study indicate that holding the probabilities of alpha and nonalpha discrimination trials near .50 results in an absence of learning curves, but leaves open the possibility that sophisticated subjects are capable of discriminating alpha and nonalpha activity. The second study deals with two questions: (a) Can sophisticated subjects learn to discriminate occipital

  6. Decision theory for discrimination-aware classification

    KAUST Repository

    Kamiran, Faisal

    2012-12-01

    Social discrimination (e.g., against females) arising from data mining techniques is a growing concern worldwide. In recent years, several methods have been proposed for making classifiers learned over discriminatory data discriminationaware. However, these methods suffer from two major shortcomings: (1) They require either modifying the discriminatory data or tweaking a specific classification algorithm and (2) They are not flexible w.r.t. discrimination control and multiple sensitive attribute handling. In this paper, we present two solutions for discrimination-aware classification that neither require data modification nor classifier tweaking. Our first and second solutions exploit, respectively, the reject option of probabilistic classifier(s) and the disagreement region of general classifier ensembles to reduce discrimination. We relate both solutions with decision theory for better understanding of the process. Our experiments using real-world datasets demonstrate that our solutions outperform existing state-ofthe-art methods, especially at low discrimination which is a significant advantage. The superior performance coupled with flexible control over discrimination and easy applicability to multiple sensitive attributes makes our solutions an important step forward in practical discrimination-aware classification. © 2012 IEEE.

  7. Discriminative Hash Tracking With Group Sparsity.

    Science.gov (United States)

    Du, Dandan; Zhang, Lihe; Lu, Huchuan; Mei, Xue; Li, Xiaoli

    2016-08-01

    In this paper, we propose a novel tracking framework based on discriminative supervised hashing algorithm. Different from previous methods, we treat tracking as a problem of object matching in a binary space. Using the hash functions, all target templates and candidates are mapped into compact binary codes, with which the target matching is conducted effectively. To be specific, we make full use of the label information to assign a compact and discriminative binary code for each sample. And to deal with out-of-sample case, multiple hash functions are trained to describe the learned binary codes, and group sparsity is introduced to the hash projection matrix to select the representative and discriminative features dynamically, which is crucial for the tracker to adapt to target appearance variations. The whole training problem is formulated as an optimization function where the hash codes and hash function are learned jointly. Extensive experiments on various challenging image sequences demonstrate the effectiveness and robustness of the proposed tracker.

  8. Pigeons' discrimination of paintings by Monet and Picasso

    OpenAIRE

    Watanabe, Shigeru; Sakamoto, Junko; Wakita, Masumi

    1995-01-01

    Pigeons successfully learned to discriminate color slides of paintings by Monet and Picasso. Following this training, they discriminated novel paintings by Monet and Picasso that had never been presented during the discrimination training. Furthermore, they showed generalization from Monet's to Cezanne's and Renoir's paintings or from Picasso's to Braque's and Matisse's paintings. These results suggest that pigeons' behavior can be controlled by complex visual stimuli in ways that suggest cat...

  9. Preexposure to (un)predictable shock modulates discriminative fear learning between cue and context: an investigation of the interaction between fear and anxiety.

    Science.gov (United States)

    Meulders, Ann; Vervliet, Bram; Fonteyne, Riet; Baeyens, Frank; Hermans, Dirk; Vansteenwegen, Debora

    2012-05-01

    It has been suggested that prior experiences with unpredictable/uncontrollable stressors facilitate subsequent fear learning and the development of anxiety disorders. However, animal research documents that preexposure to unpredictable stressors (USs) impede later fear conditioning with that US. These differential predictions were tested in a human experimental model of clinical anxiety. One (US-only) group was preexposed to unpredictable shocks, a second (Unpaired) group received explicitly unpaired presentations of a neutral shape and the shock, and a third (Paired) group received paired shape-shock presentations. Next, all groups received training with a novel shape, using the same shock (50% reinforcement). Fear responding was assessed through startle modulation and online shock-expectancy ratings. Results showed retarded fear learning in the unpredictable groups compared to the predictable group. We argue that prior experiences of unpredictability may still contribute to the development of clinical anxiety, by impeding adaptive fear learning and perpetuating the perception of unpredictability/uncontrollability.

  10. Acquisition of Social Referencing via Discrimination Training in Infants

    Science.gov (United States)

    Pelaez, Martha; Virues-Ortega, Javier; Gewirtz, Jacob L.

    2012-01-01

    This experiment investigated social referencing as a form of discriminative learning in which maternal facial expressions signaled the consequences of the infant's behavior in an ambiguous context. Eleven 4- and 5-month-old infants and their mothers participated in a discrimination-training procedure using an ABAB design. Different consequences…

  11. The relationships between major lifetime discrimination, everyday discrimination, and mental health in three racial and ethnic groups of older adults.

    Science.gov (United States)

    Ayalon, Liat; Gum, Amber M

    2011-07-01

    To evaluate the relationships between perceived exposure to major lifetime discrimination, everyday discrimination, and mental health in three racial/ethnic groups of older adults. The Health and Retirement Study is a nationally representative sample of individuals 50 years and older living in the United States. A total of 6455 Whites, 716 Latinos, and 1214 Blacks were eligible to complete a self-report psychosocial questionnaire in the year 2006. Whereas 30% of the general population reported at least one type of major lifetime discrimination, almost 45% of Black older adults reported such discrimination. Relative to the other two racial/ethnic groups (82% Whites, 82.6% Blacks), Latinos were significantly less likely to report any everyday discrimination (64.2%), whereas Blacks reported the greatest frequency of everyday discrimination. Whites reported the highest levels of life satisfaction and the lowest levels of depressive symptoms. Relative to major lifetime discrimination, everyday discrimination had a somewhat stronger correlation with mental health indicators. The relationships between discrimination and mental health outcomes were stronger for White compared to Black older adults, although everyday discrimination was still significantly associated with outcomes for Black older adults. Black older adults experience the greatest number of discriminative events, but weaker associated mental health outcomes. This could be because they have become accustomed to these experiences, benefit from social or cultural resources that serve as buffers, or selective survival, with the present sample capturing only the most resilient older adults who have learned to cope with the deleterious effects of discrimination.

  12. Using Human Rights Cases to Teach about Prejudice and Discrimination.

    Science.gov (United States)

    Power, Donald

    1983-01-01

    High school students analyze real-life case studies, taken from the files of the Ontario Human Rights Commission, to learn about the effects of prejudice, stereotyping, and discrimination with regard to native people in Canada. (RM)

  13. Discrimination against Black Students

    Science.gov (United States)

    Aloud, Ashwaq; Alsulayyim, Maryam

    2016-01-01

    Discrimination is a structured way of abusing people based on racial differences, hence barring them from accessing wealth, political participation and engagement in many spheres of human life. Racism and discrimination are inherently rooted in institutions in the society, the problem has spread across many social segments of the society including…

  14. INTERSECTIONAL DISCRIMINATION AGAINST CHILDREN

    DEFF Research Database (Denmark)

    Ravnbøl, Camilla Ida

    This paper adds a perspective to existing research on child protection by engaging in a debate on intersectional discrimination and its relationship to child protection. The paper has a twofold objective, (1) to further establish intersectionality as a concept to address discrimination against ch...... children, and (2) to illustrate the importance of addressing intersectionality within rights-based programmes of child protection....

  15. Flash-Type Discrimination

    Science.gov (United States)

    Koshak, William J.

    2010-01-01

    This viewgraph presentation describes the significant progress made in the flash-type discrimination algorithm development. The contents include: 1) Highlights of Progress for GLM-R3 Flash-Type discrimination Algorithm Development; 2) Maximum Group Area (MGA) Data; 3) Retrieval Errors from Simulations; and 4) Preliminary Global-scale Retrieval.

  16. INTERSECTIONAL DISCRIMINATION AGAINST CHILDREN

    DEFF Research Database (Denmark)

    Ravnbøl, Camilla Ida

    This paper adds a perspective to existing research on child protection by engaging in a debate on intersectional discrimination and its relationship to child protection. The paper has a twofold objective, (1) to further establish intersectionality as a concept to address discrimination against...

  17. Reversible Statistics

    DEFF Research Database (Denmark)

    Tryggestad, Kjell

    2004-01-01

    The study aims is to describe how the inclusion and exclusion of materials and calculative devices construct the boundaries and distinctions between statistical facts and artifacts in economics. My methodological approach is inspired by John Graunt's (1667) Political arithmetic and more recent work...... within constructivism and the field of Science and Technology Studies (STS). The result of this approach is here termed reversible statistics, reconstructing the findings of a statistical study within economics in three different ways. It is argued that all three accounts are quite normal, albeit...... in different ways. The presence and absence of diverse materials, both natural and political, is what distinguishes them from each other. Arguments are presented for a more symmetric relation between the scientific statistical text and the reader. I will argue that a more symmetric relation can be achieved...

  18. 判别式 Bo W分析结合自适应码本学习的人体动作识别%Application of discriminant BoW analysis combined with adaptive codebook learning in human recognition

    Institute of Scientific and Technical Information of China (English)

    蔡琼; 陈鹏慧; 郭涛

    2016-01-01

    针对一般聚类获得的码本缺乏判别性表示导致不能有效进行人体动作识别的问题,提出了一种新的自适应码本学习方法,该方法将判别式词袋(bag of words,BoW)动作表示和自适应码本学习结合,增强了码本的表示能力和特征的判别性。为了有效求解非凸目标函数,提出基于轮换优化迭代方法,即固定码本更新判别矩阵,然后判别矩阵更新固定码本,直至满足终止迭代条件,该方法为自适应码本学习提供了技术支持。仿真实验采用KTH、Hollywood2、芭蕾、i3 Dpost数据库进行判别比较,识别率比现有典型方法平均提高了4%左右,学习到的码本在特征空间中具有良好的判别性能。相比于基于光流、方向梯度直方图(histograms of oriented gradients, HOG)等方法,计算复杂度更低,实用性更好。%As the problem of ineffective human action recognition caused by lack of judgment representation of codebook ob-tained by general clustering,this paper proposed a new adaptive codebook learning method,combined discriminant bag of words with adaptive codebook learning,which had enhanced the ability to represent features of codebook discriminant.In order to ef-fectively solve the non-convex objective function,it proposed iteration of rotational optimization,that was the fixed codebook up-dated the judgment matrix,and then the judgment matrix updated the fixed codebook until it met the conditions for termination of the iteration.This method provided technical support for the adaptive codebook learning.In the simulation experiments,it tested five data sets KTH,Hollywood2,ballet,i3Dpost and facial expressions.The experimental result is about 4% recognition rate averagely higher than the existing typical methods.The learned codebook has good discrimination performance in the fea-ture space.Compared with optical flow method,the method based on the histograms of oriented gradients (HOG

  19. Limited impairments of associative learning in a mouse model of accelerated senescence.

    Science.gov (United States)

    Yang, Yi; Wu, Guang-yan; Li, Xuan; Huang, He; Hu, Bo; Yao, Juan; Wu, Bing; Sui, Jian-feng

    2013-11-15

    Research concerning impairment of associative learning during aging remains limited. The senescence-accelerated mice (SAM) prone/8 (P8) has been proposed as a useful model for the study of aging, and SAM resistant/1(SAMR1) is its control as a normal aging strain. Classical eyeblink conditioning has long been served as a model of associative learning. In order to explore the effects of aging on associative learning in SAM, the present study successively tested three paradigms of eyeblink conditioning in SAMP8 and SAMR1: classical single cue trace eyeblink conditioning (TEC), discriminative trace eyeblink conditioning and reversal learning of TEC. Behavioral performance indicated that SAMP8 could acquire limited single-cue trace eyeblink conditioning task and two-tone discrimination trace eyeblink conditioning with a relative lower acquisition rate compared to SAMR1. Both SAMP8 and SAMR1 failed to acquire reversal learning of discriminative TEC, and SAMP8' startle reflex to tone CS was lower than SAMR1. These results indicated that the impairments of aging on associative learning were incomplete in SAMP8.

  20. Action Recognition Using Discriminative Structured Trajectory Groups

    KAUST Repository

    Atmosukarto, Indriyati

    2015-01-06

    In this paper, we develop a novel framework for action recognition in videos. The framework is based on automatically learning the discriminative trajectory groups that are relevant to an action. Different from previous approaches, our method does not require complex computation for graph matching or complex latent models to localize the parts. We model a video as a structured bag of trajectory groups with latent class variables. We model action recognition problem in a weakly supervised setting and learn discriminative trajectory groups by employing multiple instance learning (MIL) based Support Vector Machine (SVM) using pre-computed kernels. The kernels depend on the spatio-temporal relationship between the extracted trajectory groups and their associated features. We demonstrate both quantitatively and qualitatively that the classification performance of our proposed method is superior to baselines and several state-of-the-art approaches on three challenging standard benchmark datasets.

  1. 基于主动鉴别字典学习的自主导航偏离控制算法%Lane departure control algorithms based on active discriminant dictionary learning for autonomous navigation

    Institute of Scientific and Technical Information of China (English)

    成新田; 唐振民

    2015-01-01

    针对传统道路偏离检测算法仅对结构化道路适用的缺陷,提出一种基于主动鉴别字典学习的偏离控制算法用于非结构化道路的偏离检测与控制.采用主动学习算法从未标记样本中学习得到主动鉴别字典,根据其结构化重构误差判断车辆偏离方向,并以此为依据控制车辆行驶方向;定义有代价的加权错误率,作为衡量算法纠偏能力的新准则.实验结果表明,所提出的算法对于结构化和非结构化道路偏离检测均有较强的有效性和可靠性.%For the defect that traditional path deviation detection algorithms apply only to structured roads, a kind of deviation control algorithm for unstructured roads based on active discrimination dictionary learning is proposed. The active discrimination dictionary is obtained from unlabeled samples by using the active leaning algorithm. According to its reconstruction error, the deviate direction of vehicles could be clear and as a basis for the next step direction control for vehicles. The definition of price weighted error is used to measure the correcting ability of the proposed algorithm. The experimental results show that the proposed algorithm has strong validity and reliability for structured and unstructured environments.

  2. FET frequency discriminator

    Science.gov (United States)

    Mawhinney, F. D.

    1982-03-01

    The FET Frequency Discriminator is an experimental microwave frequency discriminator developed for use in a specialized set-on VCO frequency memory system. Additional development and evaluation work has been done during this program to more fully determine the applicability of the FET frequency discriminator as a low-cost, expendable receiver front-end for both surveillance and ECM systems. Various methods for adjusting the frequency-to-voltage characteristic of the discriminator as well as the effects of detector characteristics and ambient temperature changes were evaluated. A number of discriminators for use in the 7- to 11-GHz and the 11to 18-GHz bands were fabricated and tested. Interim breadboard and final packaged models were either delivered or installed in developmental frequency systems. The major limitations and deficiencies of the FET frequency discriminator that were reviewed during the program include the effects of temperature, input power level variations, nonlinearity, and component repeatability. Additional effort will be required to advance the developmental status of the FET frequency discriminator to the level necessary for inclusion in low-cost receiver systems, but the basic simplicity of the approach continues to show much promise.

  3. Elimination of Sexual Discrimination in English Study

    Institute of Scientific and Technical Information of China (English)

    蒋小文

    2008-01-01

    Gender discrimination is a social attitude that is re- flected in language. The representation of gender discrimination in the English language has a variety of forms, and can be eliminated by vari- ous means. English teachers are supposed to observe these phenomenon, avoiding using sexual prejudical words and helping students to learn to use neuter words so that they can communicate with English native speakers effortlessly without hurting the latter. This thesis is tending to talk about the ways of removing sexism in English study.

  4. Investigating social discrimination of group members by laying hens.

    Science.gov (United States)

    Abeyesinghe, Siobhan M; McLeman, Morven A; Owen, Rachael C; McMahon, Claire E; Wathes, Christopher M

    2009-05-01

    Social relationships in domestic fowl are commonly assumed to rely on social recognition and its pre-requisite, discrimination of group-mates. If this is true, then the unnatural physical and social environments in which commercial laying hens are typically housed, when compared with those in which their progenitor species evolved, may compromise social function with consequent implications for welfare. Our aims were to determine whether adult hens can discriminate between unique pairs of familiar conspecifics, and to establish the most appropriate method for assessing this social discrimination. We investigated group-mate discrimination using two learning tasks in which there was bi-directional exchange of visual, auditory and olfactory information. Learning occurred in a Y-maze task (psocial discrimination or to the response task. Learning also failed to occur in this familiar/unfamiliar social discrimination task (p=0.001; n=1/10). Our findings demonstrate unequivocally that adult laying hens kept in small groups, under environmental conditions more consistent with those in which sensory capacities evolved, can discriminate group members: however, appropriate methods to demonstrate discrimination are crucial.

  5. Behavioral Correlates of 50-kHz Ultrasonic Vocalizations in Rats: Progressive Operant Discrimination Learning Reduces Frequency Modulation and Increases Overall Amplitude

    Directory of Open Access Journals (Sweden)

    Shoko Yuki

    2014-11-01

    Full Text Available Ultrasonic vocalizations (USVs in rats are thought to contain ecological signals reflecting emotional states. These USVs are centered on 50-kHz, and frequency modulation (FM is hypothesized to indicate positive emotion; however, results from recent studies are inconsistent with this hypothesis. We suspected that such inconsistencies might result from ambiguity in defining frequency modulation, and problems with acoustic analyses and behavioral protocols. We addressed these problems by applying quantitative methods for USV analyses and using a food reward operant paradigm. Our results revealed that frequency modulation varied according to the degree of positive outcomes, but the direction of change was opposite to what had been observed in previous studies. The FM in 50-kHz USVs decreased as animals learned the task and obtained more reinforcement, while USV amplitude increased as learning progressed. To reconcile these results with those from prior studies, we suggest that FM in 50-kHz USVs should be taken as an index of reward prediction errors, and USV amplitude should be considered as an index of positive emotion.

  6. 基于在线判别式字典学习的鲁棒视觉跟踪%Robust Visual Tracking Based on Online Discrimination Dictionary Learning

    Institute of Scientific and Technical Information of China (English)

    薛模根; 朱虹; 袁广林

    2015-01-01

    现有子空间跟踪方法较好地解决了目标表观变化和遮挡问题,但是它对复杂背景下目标跟踪的鲁棒性较差。针对此问题,该文首先提出一种基于Fisher准则的在线判别式字典学习模型,利用块坐标下降和替换操作设计了该模型的在线学习算法用于视觉跟踪模板更新。其次,定义候选目标编码系数与目标样本编码系数均值之间的距离为系数误差,提出以候选目标的重构误差与系数误差的组合作为粒子滤波的观测似然跟踪目标。实验结果表明:与现有跟踪方法相比,该文跟踪方法具有较强的鲁棒性和较高的跟踪精度。%The existing subspace tracking methods have well solved appearance changes and occlusions. However, they are weakly robust to complex background. To deal with this problem, firstly, this paper proposes an online discrimination dictionary learning model based on the Fisher criterion. The online discrimination dictionary learning algorithm for template updating in visual tracking is designed by using the block coordinate descent and replacing operations. Secondly, the distance between the target candidate coding coefficient and the mean of target samples coding coefficients is defined as the coefficient error. The robust visual tracking is achieved by taking the combination of the reconstruction error and the coefficient error as observation likelihood in particle filter framework. The experimental results show that the proposed method has better robustness and accuracy than the state-of-the-art trackers.

  7. Discrimination of consonance and dissonance in Java sparrows.

    Science.gov (United States)

    Watanabe, S; Uozumi, M; Tanaka, N

    2005-09-30

    Six adult Java sparrows were trained to discriminate between consonant and dissonant sounds consisting of three tones. In the consonance group, the perching response was reinforced when consonance was presented, but not when dissonance was presented. Both groups were given an inversion test, in which the first inversion of the chord was used as a stimulus. Four of six birds learned the discrimination and were given two tests. In the first test, novel consonances and novel dissonances were presented. All birds maintained the discrimination. When inverted consonances and dissonances were presented in the second test, the discriminative behavior was not well demonstrated. When novel dissonances consisting of tones with different intervals were presented in the third test, birds trained to perch for dissonance performed well, whereas those trained to perch for consonance did not. In summary, Java sparrows were able to discriminate between consonances and dissonances and demonstrated generalization to new combinations, they do not discriminate the same consonances and dissonances.

  8. Probabilistic models for semisupervised discriminative motif discovery in DNA sequences.

    Science.gov (United States)

    Kim, Jong Kyoung; Choi, Seungjin

    2011-01-01

    Methods for discriminative motif discovery in DNA sequences identify transcription factor binding sites (TFBSs), searching only for patterns that differentiate two sets (positive and negative sets) of sequences. On one hand, discriminative methods increase the sensitivity and specificity of motif discovery, compared to generative models. On the other hand, generative models can easily exploit unlabeled sequences to better detect functional motifs when labeled training samples are limited. In this paper, we develop a hybrid generative/discriminative model which enables us to make use of unlabeled sequences in the framework of discriminative motif discovery, leading to semisupervised discriminative motif discovery. Numerical experiments on yeast ChIP-chip data for discovering DNA motifs demonstrate that the best performance is obtained between the purely-generative and the purely-discriminative and the semisupervised learning improves the performance when labeled sequences are limited.

  9. Pigeons can discriminate "good" and "bad" paintings by children.

    Science.gov (United States)

    Watanabe, Shigeru

    2010-01-01

    Humans have the unique ability to create art, but non-human animals may be able to discriminate "good" art from "bad" art. In this study, I investigated whether pigeons could be trained to discriminate between paintings that had been judged by humans as either "bad" or "good". To do this, adult human observers first classified several children's paintings as either "good" (beautiful) or "bad" (ugly). Using operant conditioning procedures, pigeons were then reinforced for pecking at "good" paintings. After the pigeons learned the discrimination task, they were presented with novel pictures of both "good" and "bad" children's paintings to test whether they had successfully learned to discriminate between these two stimulus categories. The results showed that pigeons could discriminate novel "good" and "bad" paintings. Then, to determine which cues the subjects used for the discrimination, I conducted tests of the stimuli when the paintings were of reduced size or grayscale. In addition, I tested their ability to discriminate when the painting stimuli were mosaic and partial occluded. The pigeons maintained discrimination performance when the paintings were reduced in size. However, discrimination performance decreased when stimuli were presented as grayscale images or when a mosaic effect was applied to the original stimuli in order to disrupt spatial frequency. Thus, the pigeons used both color and pattern cues for their discrimination. The partial occlusion did not disrupt the discriminative behavior suggesting that the pigeons did not attend to particular parts, namely upper, lower, left or right half, of the paintings. These results suggest that the pigeons are capable of learning the concept of a stimulus class that humans name "good" pictures. The second experiment showed that pigeons learned to discriminate watercolor paintings from pastel paintings. The subjects showed generalization to novel paintings. Then, as the first experiment, size reduction test

  10. Rapid analysis of microbial systems using vibrational spectroscopy and supervised learning methods: application to the discrimination between methicillin-resistant and methicillin-susceptible Staphy

    Science.gov (United States)

    Goodacre, Royston; Rooney, Paul J.; Kell, Douglas B.

    1998-04-01

    FTIR spectra were obtained from 15 methicillin-resistant and 22 methicillin-susceptible Staphylococcus aureus strains using our DRASTIC approach. Cluster analysis showed that the major source of variation between the IR spectra was not due to their resistance or susceptibility to methicillin; indeed early studies suing pyrolysis mass spectrometry had shown that this unsupervised analysis gave information on the phage group of the bacteria. By contrast, artificial neural networks, based on a supervised learning, could be trained to recognize those aspects of the IR spectra which differentiated methicillin-resistant from methicillin- susceptible strains. These results give the first demonstration that the combination of FTIR with neural networks can provide a very rapid and accurate antibiotic susceptibility testing technique.

  11. Perceptual discrimination in fear generalization: Mechanistic and clinical implications.

    Science.gov (United States)

    Struyf, Dieter; Zaman, Jonas; Vervliet, Bram; Van Diest, Ilse

    2015-12-01

    For almost a century, Pavlovian conditioning is the imperative experimental paradigm to investigate the development and generalization of fear. However, despite the rich research tradition, the conceptualization of fear generalization has remained somewhat ambiguous. In this selective review, we focus explicitly on some challenges with the current operationalization of fear generalization and their impact on the ability to make inferences on its clinical potential and underlying processes. The main conclusion is that, despite the strong evidence that learning influences perception, current research has largely neglected the role of perceptual discriminability and its plasticity in fear generalization. We propose an alternative operationalization of generalization, where the essence is that Pavlovian conditioning itself influences the breadth of fear generalization via learning-related changes in perceptual discriminability. Hence a conceptualization of fear generalization is incomplete without an in-depth analysis of processes of perceptual discriminability. Furthermore, this highlights perceptual learning and discriminability as important future targets for pre-clinical and clinical research.

  12. Longitudinal investigation on learned helplessness tested under negative and positive reinforcement involving stimulus control.

    Science.gov (United States)

    Oliveira, Emileane C; Hunziker, Maria Helena

    2014-07-01

    In this study, we investigated whether (a) animals demonstrating the learned helplessness effect during an escape contingency also show learning deficits under positive reinforcement contingencies involving stimulus control and (b) the exposure to positive reinforcement contingencies eliminates the learned helplessness effect under an escape contingency. Rats were initially exposed to controllable (C), uncontrollable (U) or no (N) shocks. After 24h, they were exposed to 60 escapable shocks delivered in a shuttlebox. In the following phase, we selected from each group the four subjects that presented the most typical group pattern: no escape learning (learned helplessness effect) in Group U and escape learning in Groups C and N. All subjects were then exposed to two phases, the (1) positive reinforcement for lever pressing under a multiple FR/Extinction schedule and (2) a re-test under negative reinforcement (escape). A fourth group (n=4) was exposed only to the positive reinforcement sessions. All subjects showed discrimination learning under multiple schedule. In the escape re-test, the learned helplessness effect was maintained for three of the animals in Group U. These results suggest that the learned helplessness effect did not extend to discriminative behavior that is positively reinforced and that the learned helplessness effect did not revert for most subjects after exposure to positive reinforcement. We discuss some theoretical implications as related to learned helplessness as an effect restricted to aversive contingencies and to the absence of reversion after positive reinforcement. This article is part of a Special Issue entitled: insert SI title.

  13. Presumed "prefrontal cortex" lesions in pigeons : effects on visual discrimination performance

    OpenAIRE

    Aldavert-Vera, Laura; Costa-Miserachs, David; Divac, Ivan; Delius, Juan

    1999-01-01

    The posterodorsolateral neostriatum (PDLNS) in pigeons may be an equivalent of the prefrontal cortex (PFC) in mammals. Here we report that lesions of this brain region in pigeons have a detrimental effect on various learned visual discriminations. Pigeons with lesions of the overlying area corticoidea dorsolateralis (CDL) served as controls. Both the postoperative re-learning to criterion of a preoperatively learned simultaneous double visual mirror pattern discrimination and the learning of ...

  14. Orthogonal Sparsity Preserving Discriminant Analysis Based on Manifold Learning%基于流形学习的正交稀疏保留投影鉴别分析

    Institute of Scientific and Technical Information of China (English)

    凌若冰; 荆晓远; 吴飞; 姚永芳; 李文倩

    2015-01-01

    Sparsity Preserving Projections ( SPP) is an effective feature extraction method,which can preserve the sparse reconstruction re-lations among samples. However,according to the manifold learning theory,the local manifold structure of samples is more important than the global Euclidean structure of samples. SPP cannot get a set of orthogonal projection vectors,and thus there exists redundant informa-tion among the obtained features. To address these problems of SPP,propose a novel approach called Manifold Learning based Iterative Orthogonal Sparsity preserving Discriminant Analysis ( MLIOSDA) ,which introduces the idea of manifold learning into SPP and obtains orthogonal projection space. Obtain optimal projection vectors in an iterative manner. Also provide a terminating criterion to finish the it-eration. Experimental results on CAS-PEAL and PolyU databases demonstrate that the proposed approach can effectively improve the rec-ognition results compared with some related methods.%稀疏保留投影( SPP)是一种保留样本间的稀疏重构关系的特征提取方法。但是根据流形学习理论,考虑局部流形结构比考虑全局欧氏结构更重要。此外,SPP得到的不是一组正交的投影向量,特征间存在冗余信息。为解决该问题,文中提出一种改进的稀疏保留投影算法,在SPP中引入有监督的流形学习,使得所得投影空间正交,并用迭代的方式求解最优投影变换,称为基于流形学习的迭代正交稀疏保留鉴别分析( MLIOSDA)。同时提出一种终止准则终止迭代。在CAS-PEAL人脸数据库和PolyU掌纹数据库的实验结果表明,文中提出的方法与一些相关方法相比有效地提高了识别结果。

  15. Discriminative Parameter Estimation for Random Walks Segmentation

    OpenAIRE

    Baudin, Pierre-Yves; Goodman, Danny; Kumar, Puneet; Azzabou, Noura; Carlier, Pierre G.; Paragios, Nikos; Pawan Kumar, M.

    2013-01-01

    International audience; The Random Walks (RW) algorithm is one of the most e - cient and easy-to-use probabilistic segmentation methods. By combining contrast terms with prior terms, it provides accurate segmentations of medical images in a fully automated manner. However, one of the main drawbacks of using the RW algorithm is that its parameters have to be hand-tuned. we propose a novel discriminative learning framework that estimates the parameters using a training dataset. The main challen...

  16. Reverse logistics for recycling: The customer service

    Directory of Open Access Journals (Sweden)

    Reis, E.

    2009-01-01

    Full Text Available Customer service is a central concern in the logistics practice and a study topic in the forward logistics research. This article investigates the elements of customer service and their importance in reverse logistics for recycling. Since consumer is the first intervenient in any reverse system that aims to recycle household residues, the provision of an adequate customer service gains an increased importance. Applying multivariate statistical methods (exploratory factor analysis, confirmatory factor analysis and discriminant analysis to the data from a sample of 267 Portuguese citizens, this study identifies the levels of customer service in this reverse logistics chain and evaluates their relative importance in achieving consumers’ participation. The study finds that, as in forward logistics, the customer service in reverse channels for recycling also has a hard and a soft level, being the former more important than the later. The results of this research suggest important guidelines to improve such a complex logistics service.

  17. Do discrimination tasks discourage multi-dimensional stimulus processing? Evidence from a cross-modal object discrimination in rats.

    Science.gov (United States)

    Jeffery, Kathryn J

    2007-11-02

    Neurobiologists are becoming increasingly interested in how complex cognitive representations are formed by the integration of sensory stimuli. To this end, discrimination tasks are frequently used to assess perceptual and cognitive processes in animals, because they are easy to administer and score, and the ability of an animal to make a particular discrimination establishes beyond doubt that the necessary perceptual/cognitive processes are present. It does not, however, follow that absence of discrimination means the animal cannot make a particular perceptual judgement; it may simply mean that the animal did not manage to discover the relevant discriminative stimulus when trying to learn the task. Here, it is shown that rats did not learn a cross-modal object discrimination (requiring association of each object's visual appearance with its odour) when trained on the complete task from the beginning. However, they could eventually make the discrimination when trained on the component parts step by step, showing that they were able to do the necessary cross-modal integration in the right circumstances. This finding adds to growing evidence that discrimination tasks tend to encourage feature-based discrimination, perhaps by engaging automatic, habit-based brain systems. Thus, they may not be the best way to assess the formation of multi-dimensional stimulus representations of the kind needed in more complex cognitive processes such as declarative memory. Instead, more natural tasks such as spontaneous exploration may be preferable.

  18. The Influence of Discrimination and Fairness on Collective Self-Esteem

    NARCIS (Netherlands)

    Scheepers, Daan; Spears, Russell; Manstead, Antony S. R.; Doosje, Bertjan

    2009-01-01

    This article examines the influence of discrimination and fairness on collective self-esteem. Whereas social identity theory's self-esteem hypothesis emphasizes that discrimination can enhance self-esteem, the authors contend that this self-esteem advantage will actually reverse when groups are prim

  19. The Influence of Discrimination and Fairness on Collective Self-Esteem

    NARCIS (Netherlands)

    Scheepers, Daan; Spears, Russell; Manstead, Antony S. R.; Doosje, Bertjan

    2009-01-01

    This article examines the influence of discrimination and fairness on collective self-esteem. Whereas social identity theory's self-esteem hypothesis emphasizes that discrimination can enhance self-esteem, the authors contend that this self-esteem advantage will actually reverse when groups are prim

  20. The influence of discrimination and fairness on collective self-esteem

    NARCIS (Netherlands)

    Scheepers, D.; Spears, R.; Manstead, A.S.R.; Doosje, B.

    2009-01-01

    This article examines the influence of discrimination and fairness on collective self-esteem. Whereas social identity theory's self-esteem hypothesis emphasizes that discrimination can enhance self-esteem, the authors contend that this self-esteem advantage will actually reverse when groups are prim

  1. The Influence of Discrimination and Fairness on Collective Self-Esteem

    NARCIS (Netherlands)

    Scheepers, Daan; Spears, Russell; Manstead, Antony S. R.; Doosje, Bertjan

    This article examines the influence of discrimination and fairness on collective self-esteem. Whereas social identity theory's self-esteem hypothesis emphasizes that discrimination can enhance self-esteem, the authors contend that this self-esteem advantage will actually reverse when groups are

  2. The influence of discrimination and fairness on collective self-esteem

    NARCIS (Netherlands)

    Scheepers, D.; Spears, R.; Manstead, A.S.R.; Doosje, B.

    2009-01-01

    This article examines the influence of discrimination and fairness on collective self-esteem. Whereas social identity theory's self-esteem hypothesis emphasizes that discrimination can enhance self-esteem, the authors contend that this self-esteem advantage will actually reverse when groups are

  3. Aptitude Tests and Discrimination

    Science.gov (United States)

    Coupland, D. E.

    1970-01-01

    Explains why in the United States the feeling is increasing that much of the aptitude testing now being done discriminates against minority group members seeking employment. Skeptical of eliminating the discriminatory aspects of testing, the article raises the question of eliminating testing itself. (DM)

  4. Color measurement and discrimination

    Science.gov (United States)

    Wandell, B. A.

    1985-01-01

    Theories of color measurement attempt to provide a quantative means for predicting whether two lights will be discriminable to an average observer. All color measurement theories can be characterized as follows: suppose lights a and b evoke responses from three color channels characterized as vectors, v(a) and v(b); the vector difference v(a) - v(b) corresponds to a set of channel responses that would be generated by some real light, call it *. According to theory a and b will be discriminable when * is detectable. A detailed development and test of the classic color measurement approach are reported. In the absence of a luminance component in the test stimuli, a and b, the theory holds well. In the presence of a luminance component, the theory is clearly false. When a luminance component is present discrimination judgements depend largely on whether the lights being discriminated fall in separate, categorical regions of color space. The results suggest that sensory estimation of surface color uses different methods, and the choice of method depends upon properties of the image. When there is significant luminance variation a categorical method is used, while in the absence of significant luminance variation judgments are continuous and consistant with the measurement approach.

  5. Sex Discrimination in Coaching.

    Science.gov (United States)

    Dessem, Lawrence

    1980-01-01

    Even in situations in which the underpayment of girls' coaches is due to the sex of the students coached rather than to the sex of the coaches, the coaches and the girls coached are victims of unlawful discrimination. Available from Harvard Women's Law Journal, Harvard Law School, Cambridge, MA 02138. (Author/IRT)

  6. Education and Gender Discrimination

    Science.gov (United States)

    Sumi, V. S.

    2012-01-01

    This paper discusses the status of women education in present education system and some measures to overcome the lags existing. Discrimination against girls and women in the developing world is a devastating reality. It results in millions of individual tragedies, which add up to lost potential for entire countries. Gender bias in education is an…

  7. Discrimination. Opposing Viewpoints Series.

    Science.gov (United States)

    Williams, Mary E., Ed.

    Books in the Opposing Viewpoints series challenge readers to question their own opinions and assumptions. By reading carefully balanced views, readers confront new ideas on the topic of interest. The Civil Rights Act of 1964, which prohibited job discrimination based on age, race, religion, gender, or national origin, provided the groundwork for…

  8. Immunological self, nonself discrimination

    DEFF Research Database (Denmark)

    Guillet, J G; Lai, M Z; Briner, T J

    1987-01-01

    The ability of immunodominant peptides derived from several antigen systems to compete with each other for T cell activation was studied. Only peptides restricted by a given transplantation antigen are mutually competitive. There is a correlation between haplotype restriction, ability to bind to ...... that provides a basis for explaining self, nonself discrimination as well as alloreactivity....

  9. Analytic boosted boson discrimination

    Energy Technology Data Exchange (ETDEWEB)

    Larkoski, Andrew J.; Moult, Ian; Neill, Duff [Center for Theoretical Physics, Massachusetts Institute of Technology,Cambridge, MA 02139 (United States)

    2016-05-20

    Observables which discriminate boosted topologies from massive QCD jets are of great importance for the success of the jet substructure program at the Large Hadron Collider. Such observables, while both widely and successfully used, have been studied almost exclusively with Monte Carlo simulations. In this paper we present the first all-orders factorization theorem for a two-prong discriminant based on a jet shape variable, D{sub 2}, valid for both signal and background jets. Our factorization theorem simultaneously describes the production of both collinear and soft subjets, and we introduce a novel zero-bin procedure to correctly describe the transition region between these limits. By proving an all orders factorization theorem, we enable a systematically improvable description, and allow for precision comparisons between data, Monte Carlo, and first principles QCD calculations for jet substructure observables. Using our factorization theorem, we present numerical results for the discrimination of a boosted Z boson from massive QCD background jets. We compare our results with Monte Carlo predictions which allows for a detailed understanding of the extent to which these generators accurately describe the formation of two-prong QCD jets, and informs their usage in substructure analyses. Our calculation also provides considerable insight into the discrimination power and calculability of jet substructure observables in general.

  10. Discrimination and its Effects.

    Science.gov (United States)

    Thomas, Clarence

    1983-01-01

    Reviews challenges facing Black professionals committed to further promoting civil rights. Focuses on the Federal government role, particularly regarding racial discrimination in employment. Warns against the acceptance of orthodoxies, and calls for new action and the exercising of intellectual freedom. (KH)

  11. Conditioning procedure and color discrimination in the honeybee Apis mellifera

    Science.gov (United States)

    Giurfa, Martin

    We studied the influence of the conditioning procedure on color discrimination by free-flying honeybees. We asked whether absolute and differential conditioning result in different discrimination capabilities for the same pairs of colored targets. In absolute conditioning, bees were rewarded on a single color; in differential conditioning, bees were rewarded on the same color but an alternative, non-rewarding, similar color was also visible. In both conditioning procedures, bees learned their respective task and could also discriminate the training stimulus from a novel stimulus that was perceptually different from the trained one. Discrimination between perceptually closer stimuli was possible after differential conditioning but not after absolute conditioning. Differences in attention inculcated by these training procedures may underlie the different discrimination performances of the bees.

  12. Examining Workplace Discrimination in a Discrimination-Free Environment

    OpenAIRE

    Braxton, Shawn Lamont

    2010-01-01

    Examining Workplace Discrimination in a Discrimination-Free Environment Shawn L. Braxton Abstract The purpose of this study is to explore how racial and gender discrimination is reproduced in concrete workplace settings even when anti-discrimination policies are present, and to understand the various reactions utilized by those who commonly experience it. I have selected a particular medical center, henceforth referred to by a pseudonym, â The Bliley Medical Centerâ as my case ...

  13. Managing Reverse Logistics or Reversing Logistics Management?

    OpenAIRE

    Brito, Marisa

    2004-01-01

    textabstractIn the past, supply chains were busy fine-tuning the logistics from raw material to the end customer. Today an increasing flow of products is going back in the chain. Thus, companies have to manage reverse logistics as well.This thesis contributes to a better understanding of reverse logistics. The thesis brings insights on reverse logistics decision-making and it lays down theoretical principles for reverse logistics as a research field.In particular it puts together a framework ...

  14. The relative merits of discriminating and non-discriminating dosemeters

    DEFF Research Database (Denmark)

    Marshal, T. O.; Christensen, Palle; Julius, H. W.;

    1986-01-01

    The need for discriminating and non-discriminating personal dosemeters in the field of radiological protection is examined. The ability of various types of dosemeter to meet these needs is also discussed. It is concluded that there is a need for discriminating dosemeters but in the majority of ca...

  15. Requirement of the auditory association cortex for discrimination of vowel-like sounds in rats.

    Science.gov (United States)

    Kudoh, Masaharu; Nakayama, Yoko; Hishida, Ryuichi; Shibuki, Katsuei

    2006-11-27

    We investigated the roles of the auditory cortex in discrimination learning of vowel-like sounds consisting of multiple formants. Rats were trained to discriminate between synthetic sounds with four formants. Bilateral electrolytic lesions including the primary auditory cortex and the dorsal auditory association cortex impaired multiformant discrimination, whereas they did not significantly affect discrimination between sounds with a single formant or between pure tones. Local lesions restricted to the dorsal/rostral auditory association cortex were sufficient to attenuate multiformant discrimination learning, and lesions restricted to the primary auditory cortex had no significant effects. These findings indicate that the dorsal/rostral auditory association cortex but not the primary auditory cortex is required for discrimination learning of vowel-like sounds with multiple formants in rats.

  16. Plant Leaf Recognition through Local Discriminative Tangent Space Alignment

    Directory of Open Access Journals (Sweden)

    Chuanlei Zhang

    2016-01-01

    Full Text Available Manifold learning based dimensionality reduction algorithms have been payed much attention in plant leaf recognition as the algorithms can select a subset of effective and efficient discriminative features in the leaf images. In this paper, a dimensionality reduction method based on local discriminative tangent space alignment (LDTSA is introduced for plant leaf recognition based on leaf images. The proposed method can embrace part optimization and whole alignment and encapsulate the geometric and discriminative information into a local patch. The experiments on two plant leaf databases, ICL and Swedish plant leaf datasets, demonstrate the effectiveness and feasibility of the proposed method.

  17. Employment Age Discrimination on Women

    Institute of Scientific and Technical Information of China (English)

    黄捧

    2015-01-01

    Employment age discrimination against women is not an unusual phenomenon in China.Through describing the present situation and negative effect of this phenomenon,this paper claims laws are very important weapon to eliminate age discrimination against women.

  18. Effects of age and expertise on tactile learning in humans.

    Science.gov (United States)

    Reuter, Eva-Maria; Voelcker-Rehage, Claudia; Vieluf, Solveig; Godde, Ben

    2014-08-01

    Repetitive tactile stimulation is a well-established tool for inducing somatosensory cortical plasticity and changes in tactile perception. Previous studies have suggested that baseline performance determines the amount of stimulation-induced learning differently in specific populations. Older adults with lower baseline performance than young adults, but also experts, with higher baseline performance than non-experts of the same age, have been found to profit most from such interventions. This begs the question of how age-related and expertise-related differences in tactile learning are reflected in neurophysiological correlates. In two experiments, we investigated how tactile learning depends on age (experiment 1) and expertise (experiment 2). We assessed tactile spatial and temporal discrimination accuracy and event-related potentials (ERPs) in 57 persons of different age and expertise groups before and after a 30-min tactile stimulation intervention. The intervention increased accuracy in temporal (found in experiment 1) and spatial (found in experiment 2) discrimination. Experts improved more than non-experts in spatial discrimination. Lower baseline performance was associated with higher learning gain in experts and non-experts. After the intervention, P300 latencies were reduced in young adults and amplitudes were increased in late middle-aged adults in the temporal discrimination task. Experts showed a steeper P300 parietal-to-frontal gradient after the stimulation. We demonstrated that tactile stimulation partially reverses the age-related decline in late middle-aged adults and increases processing speed in young adults. We further showed that learning gain depends on baseline performance in both non-experts and experts. In experts, however, the upper limit for learning seems to be shifted to a higher level. © 2014 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  19. Chronic pravastatin but not atorvastatin treatment impairs cognitive function in two rodent models of learning and memory.

    Directory of Open Access Journals (Sweden)

    Sarah A Stuart

    Full Text Available Statins are some of the most commonly prescribed drugs and are used to reduce blood cholesterol. Recent evidence suggests that, in some patients, they may adversely influence cognitive function including causing memory impairments. These clinical observations have led to statin prescriptions now including a warning about possible cognitive impairments. In order to better understand the relationship between statin treatment and cognitive function, studies in animals are needed. The present study investigated the effects of chronic treatment with two statins, pravastatin and atorvastatin, in two rodent models of learning and memory. Adult rats were treated once daily with pravastatin (10 mg/kg, orally or atorvostatin (10 mg/kg, orally for 18 days. Before, during and after treatment, animals were tested in a simple discrimination and reversal learning task. On the last day of treatment and following one week withdrawal, animals were also tested in a task of novel object discrimination. Pravastatin tended to impair learning over the last few days of treatment and this effect was fully reversed once treatment ceased. In the novel object discrimination task, pravastatin significantly impaired object recognition memory. No effects were observed for atorvostatin in either task. These data suggest that chronic treatment with pravastatin impairs working and recognition memory in rodents. The reversibility of the effects on cessation of treatment is similar to what has been observed in patients, but the lack of effect of atorvostatin suggests that lipophilicity may not be a major factor influencing statin-induced cognitive impairments.

  20. Price Discrimination: A Classroom Experiment

    Science.gov (United States)

    Aguiló, Paula; Sard, Maria; Tugores, Maria

    2016-01-01

    In this article, the authors describe a classroom experiment aimed at familiarizing students with different types of price discrimination (first-, second-, and third-degree price discrimination). During the experiment, the students were asked to decide what tariffs to set as monopolists for each of the price discrimination scenarios under…

  1. Price Discrimination: Lessons for Consumers.

    Science.gov (United States)

    Maynes, E. Scott

    1990-01-01

    Explains price and product discrimination, showing how intelligent consumers can achieve increased purchasing power of their income and discusses how consumer educators can explain this discrimination. Evaluates the pros and cons of price/product discrimination from the social viewpoint. (Author/JOW)

  2. Transgender Discrimination and the Law

    Science.gov (United States)

    Trotter, Richard

    2010-01-01

    An emerging area of law is developing regarding sex/gender identity discrimination, also referred to as transgender discrimination, as distinguished from discrimination based on sexual orientation. A transgendered individual is defined as "a person who has a gender-identity disorder which is a persistent discomfort about one?s assigned sex or…

  3. Racial Discrimination and Competition

    OpenAIRE

    Ross Levine; Alexey Levkov; Yona Rubinstein

    2008-01-01

    This paper assesses the impact of competition on racial discrimination. The dismantling of inter- and intrastate bank restrictions by U.S. states from the mid-1970s to the mid-1990s reduced financial market imperfections, lowered entry barriers facing nonfinancial firms, and boosted the rate of new firm formation. We use bank deregulation to identify an exogenous intensification of competition in the nonfinancial sector, and evaluate its impact on the racial wage gap, which is that component ...

  4. Optimal time discrimination

    OpenAIRE

    Coşkun, Filiz; Sayalı, Zeynep Ceyda; Gürbüz, Emine; Balcı, Fuat

    2015-01-01

    Optimal Time Discrimination Journal: Quarterly Journal of Experimental Psychology Manuscript ID: QJE-STD 14-039.R1 Manuscript Type: Standard Article Date Submitted by the Author: n/a Complete List of Authors: Çoskun, Filiz; Koç University, Psychology Sayalı Ungerer, Zeynep; Koç University, Psychology Gürbüz, Emine; Koç University, Psychology Balcı, Fuat; Koç University, Psychology Keywords: Decision making, Interval Timing, Optimality, Response Times, Temporal ...

  5. Managing Reverse Logistics or Reversing Logistics Management?

    NARCIS (Netherlands)

    M.P. de Brito (Marisa)

    2004-01-01

    textabstractIn the past, supply chains were busy fine-tuning the logistics from raw material to the end customer. Today an increasing flow of products is going back in the chain. Thus, companies have to manage reverse logistics as well.This thesis contributes to a better understanding of reverse

  6. Managing Reverse Logistics or Reversing Logistics Management?

    NARCIS (Netherlands)

    M.P. de Brito (Marisa)

    2004-01-01

    textabstractIn the past, supply chains were busy fine-tuning the logistics from raw material to the end customer. Today an increasing flow of products is going back in the chain. Thus, companies have to manage reverse logistics as well.This thesis contributes to a better understanding of reverse log

  7. Perceptual learning improves adult amblyopic vision through rule-based cognitive compensation.

    Science.gov (United States)

    Zhang, Jun-Yun; Cong, Lin-Juan; Klein, Stanley A; Levi, Dennis M; Yu, Cong

    2014-04-01

    We investigated whether perceptual learning in adults with amblyopia could be enabled to transfer completely to an orthogonal orientation, which would suggest that amblyopic perceptual learning results mainly from high-level cognitive compensation, rather than plasticity in the amblyopic early visual brain. Nineteen adults (mean age = 22.5 years) with anisometropic and/or strabismic amblyopia were trained following a training-plus-exposure (TPE) protocol. The amblyopic eyes practiced contrast, orientation, or Vernier discrimination at one orientation for six to eight sessions. Then the amblyopic or nonamblyopic eyes were exposed to an orthogonal orientation via practicing an irrelevant task. Training was first performed at a lower spatial frequency (SF), then at a higher SF near the cutoff frequency of the amblyopic eye. Perceptual learning was initially orientation specific. However, after exposure to the orthogonal orientation, learning transferred to an orthogonal orientation completely. Reversing the exposure and training order failed to produce transfer. Initial lower SF training led to broad improvement of contrast sensitivity, and later higher SF training led to more specific improvement at high SFs. Training improved visual acuity by 1.5 to 1.6 lines (P learning suggests that perceptual learning in amblyopia may reflect high-level learning of rules for performing a visual discrimination task. These rules are applicable to new orientations to enable learning transfer. Therefore, perceptual learning may improve amblyopic vision mainly through rule-based cognitive compensation.

  8. Workplace discrimination and cancer.

    Science.gov (United States)

    McKenna, Maureen A; Fabian, Ellen; Hurley, Jessica E; McMahon, Brian T; West, Steven L

    2007-01-01

    Data from the Equal Employment Opportunity Commission (EEOC) Integrated Mission System database were analyzed with specific reference to allegations of workplace discrimination filed by individuals with cancer under ADA Title One. These 6,832 allegations, filed between July 27, 1992 and September 30, 2003, were compared to 167,798 allegations from a general disability population on the following dimensions: type of workplace discrimination; demographic characteristics of the charging parties (CPs); the industry designation, location, and size of employers; and the outcome or resolution of EEOC investigations. Results showed allegations derived from CPs with cancer were more likely than those in the general disability population to include issues involving discharge, terms and conditions of employment, lay-off, wages, and demotion. Compared to the general disability group, CPs with cancer were more likely to be female, older, and White. Allegations derived from CPs with cancer were also more likely to be filed against smaller employers (15-100 workers) or those in service industries. Finally, the resolution of allegations by CPs with cancer were more likely to be meritorious than those filed from the general disability population; that is, actual discrimination is more likely to have occurred.

  9. [Comment on] Statistical discrimination

    Science.gov (United States)

    Chinn, Douglas

    In the December 8, 1981, issue of Eos, a news item reported the conclusion of a National Research Council study that sexual discrimination against women with Ph.D.'s exists in the field of geophysics. Basically, the item reported that even when allowances are made for motherhood the percentage of female Ph.D.'s holding high university and corporate positions is significantly lower than the percentage of male Ph.D.'s holding the same types of positions. The sexual discrimination conclusion, based only on these statistics, assumes that there are no basic psychological differences between men and women that might cause different populations in the employment group studied. Therefore, the reasoning goes, after taking into account possible effects from differences related to anatomy, such as women stopping their careers in order to bear and raise children, the statistical distributions of positions held by male and female Ph.D.'s ought to be very similar to one another. Any significant differences between the distributions must be caused primarily by sexual discrimination.

  10. Locality-Constrained Discriminative Learning and Coding

    Science.gov (United States)

    2015-06-12

    female Caucasian subjects (show in Fig. 3 (d)). There are 4 makeup statues (a) no makeup; (b) lipstick only; (c) eye makeup only; and (d) a full makeup...including lipstick , foundation, blush and eye makeup. Hence, the assembled dataset contains total 204 images and four images per subject. We randomly

  11. Reversible Thermoset Adhesives

    Science.gov (United States)

    Mac Murray, Benjamin C. (Inventor); Tong, Tat H. (Inventor); Hreha, Richard D. (Inventor)

    2016-01-01

    Embodiments of a reversible thermoset adhesive formed by incorporating thermally-reversible cross-linking units and a method for making the reversible thermoset adhesive are provided. One approach to formulating reversible thermoset adhesives includes incorporating dienes, such as furans, and dienophiles, such as maleimides, into a polymer network as reversible covalent cross-links using Diels Alder cross-link formation between the diene and dienophile. The chemical components may be selected based on their compatibility with adhesive chemistry as well as their ability to undergo controlled, reversible cross-linking chemistry.

  12. Olfactory Discrimination Training Up-Regulates and Reorganizes Expression of MicroRNAs in Adult Mouse Hippocampus

    Directory of Open Access Journals (Sweden)

    Neil R Smalheiser

    2010-01-01

    Full Text Available Adult male mice (strain C57Bl/6J were trained to execute nose-poke responses for water reinforcement; then they were randomly assigned to either of two groups: Olfactory discrimination training (exposed to two odours with reward contingent upon correctly responding to one odour or pseudo-training (exposed to two odours with reward not contingent upon response. These were run in yoked fashion and killed when the discrimination-trained mouse reached a learning criterion of 70% correct responses in 20 trials, occurring after three sessions (a total of ~40 min of training. The hippocampus was dissected bilaterally from each mouse (N=7 in each group and profiling of 585 miRNAs (microRNAs was carried out using multiplex RT–PCR (reverse transcription–PCR plates. A significant global up-regulation of miRNA expression was observed in the discrimination training versus pseudo-training comparison; when tested individually, 29 miRNAs achieved significance at P=0.05. miR-10a showed a 2.7-fold increase with training, and is predicted to target several learning-related mRNAs including BDNF (brain-derived neurotrophic factor, CAMK2b (calcium/calmodulin-dependent protein kinase IIβ, CREB1 (cAMP-response-element-binding protein 1 and ELAVL2 [ELAV (embryonic lethal, abnormal vision, Drosophila-like; Hu B]. Analysis of miRNA pairwise correlations revealed the existence of several miRNA co-expression modules that were specific to the training group. These in vivo results indicate that significant, dynamic and co-ordinated changes in miRNA expression accompany early stages of learning.

  13. Effects of dopamine depletion on LFP oscillations in striatum are task- and learning-dependent and selectively reversed by L-DOPA.

    Science.gov (United States)

    Lemaire, Nuné; Hernandez, Ledia F; Hu, Dan; Kubota, Yasuo; Howe, Mark W; Graybiel, Ann M

    2012-10-30

    A major physiologic sign in Parkinson disease is the occurrence of abnormal oscillations in cortico-basal ganglia circuits, which can be normalized by L-DOPA therapy. Under normal circumstances, oscillatory activity in these circuits is modulated as behaviors are learned and performed, but how dopamine depletion affects such modulation is not yet known. We here induced unilateral dopamine depletion in the sensorimotor striatum of rats and then recorded local field potential (LFP) activity in the dopamine-depleted region and its contralateral correspondent as we trained the rats on a conditional T-maze task. Unexpectedly, the dopamine depletion had little effect on oscillations recorded in the pretask baseline period. Instead, the depletion amplified oscillations across delta (~3 Hz), theta (~8 Hz), beta (~13 Hz), and low-gamma (~48 Hz) ranges selectively during task performance times when each frequency band was most strongly modulated, and only after extensive training had occurred. High-gamma activity (65-100 Hz), in contrast, was weakened independent of task time or learning stage. The depletion also increased spike-field coupling of fast-spiking interneurons to low-gamma oscillations. L-DOPA therapy normalized all of these effects except those at low gamma. Our findings suggest that the task-related and learning-related dynamics of LFP oscillations are the primary targets of dopamine depletion, resulting in overexpression of behaviorally relevant oscillations. L-DOPA normalizes these dynamics except at low-gamma, linked by spike-field coupling to fast-spiking interneurons, now known to undergo structural changes after dopamine depletion and to lack normalization of spike activity following l-DOPA therapy.

  14. Simultaneous discrimination of speed is more difficult than simultaneous discrimination of size for both pigeons and people

    Directory of Open Access Journals (Sweden)

    Olga F. Lazareva

    2017-08-01

    Full Text Available Previous reports suggest that pigeons are highly sensitive to speed of motion (Cook, Beale, Koban, 2011; Herbranson, Fremouw, & Shimp, 2002. In contrast, we found that pigeons required more extensive training to learn speed discrimination than size discrimination (Lazareva, Young, & Wasserman, 2014. However, our results were based on a comparison of two experiments conducted in different laboratories, complicating the interpretation of the data. Here, we trained pigeons to perform size discrimination or speed discrimination in a two-alternative simultaneous discrimination task using a within-subject design. All birds acquired size discrimination much faster than speed discrimination, confirming our prior report. We further explored pigeons’ sensitivity to differences in speed and size by training them to discriminate two end-point stimuli in a two-alternative forced-choice task and then presenting a wide range of testing stimuli located between the training end-point stimuli. The results again indicated weaker control by the differences in speed in comparison to size; comparable results were obtained for human participants.

  15. Optimal sequencing during category learning: Testing a dual-learning systems perspective.

    Science.gov (United States)

    Noh, Sharon M; Yan, Veronica X; Bjork, Robert A; Maddox, W Todd

    2016-10-01

    Recent studies demonstrate that interleaving the exemplars of different categories, rather than blocking exemplars by category, can enhance inductive learning-the ability to categorize new exemplars-presumably because interleaving affords discriminative contrasts between exemplars from different categories. Consistent with this view, other studies have demonstrated that decreasing between-category similarity and increasing within-category variability can eliminate or even reverse the interleaving benefit. We tested another hypothesis, one based on the dual-learning systems framework-namely, that the optimal schedule for learning categories should depend on an interaction of the cognitive system that mediates learning and the structure of the particular category being learned. Blocking should enhance rule-based category learning, which is mediated by explicit, hypothesis-testing processes, whereas interleaving should enhance information-integration category learning, which is mediated by an implicit, procedural-based learning system. Consistent with this view, we found a crossover interaction between schedule (blocked vs. interleaved) and category structure (rule-based vs. information-integration). Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Braille character discrimination in blindfolded human subjects.

    Science.gov (United States)

    Kauffman, Thomas; Théoret, Hugo; Pascual-Leone, Alvaro

    2002-04-16

    Visual deprivation may lead to enhanced performance in other sensory modalities. Whether this is the case in the tactile modality is controversial and may depend upon specific training and experience. We compared the performance of sighted subjects on a Braille character discrimination task to that of normal individuals blindfolded for a period of five days. Some participants in each group (blindfolded and sighted) received intensive Braille training to offset the effects of experience. Blindfolded subjects performed better than sighted subjects in the Braille discrimination task, irrespective of tactile training. For the left index finger, which had not been used in the formal Braille classes, blindfolding had no effect on performance while subjects who underwent tactile training outperformed non-stimulated participants. These results suggest that visual deprivation speeds up Braille learning and may be associated with behaviorally relevant neuroplastic changes.

  17. Direct Neighborhood Discriminant Analysis for Face Recognition

    Directory of Open Access Journals (Sweden)

    Miao Cheng

    2008-01-01

    Full Text Available Face recognition is a challenging problem in computer vision and pattern recognition. Recently, many local geometrical structure-based techiniques are presented to obtain the low-dimensional representation of face images with enhanced discriminatory power. However, these methods suffer from the small simple size (SSS problem or the high computation complexity of high-dimensional data. To overcome these problems, we propose a novel local manifold structure learning method for face recognition, named direct neighborhood discriminant analysis (DNDA, which separates the nearby samples of interclass and preserves the local within-class geometry in two steps, respectively. In addition, the PCA preprocessing to reduce dimension to a large extent is not needed in DNDA avoiding loss of discriminative information. Experiments conducted on ORL, Yale, and UMIST face databases show the effectiveness of the proposed method.

  18. Vine variety discrimination with airborne imaging spectroscopy

    Science.gov (United States)

    Ferreiro-Armán, M.; Alba-Castro, J. L.; Homayouni, S.; da Costa, J. P.; Martín-Herrero, J.

    2007-09-01

    We aim at the discrimination of varieties within a single plant species (Vitis vinifera) by means of airborne hyperspectral imagery collected using a CASI-2 sensor and supervised classification, both under constant and varying within-scene illumination conditions. Varying illumination due to atmospheric conditions (such as clouds) and shadows cause different pixels belonging to the same class to present different spectral vectors, increasing the within class variability and hindering classification. This is specially serious in precision applications such as variety discrimination in precision agriculture, which depends on subtle spectral differences. In this study, we use machine learning techniques for supervised classification, and we also analyze the variability within and among plots and within and among sites, in order to address the generalizability of the results.

  19. Object recognition with hierarchical discriminant saliency networks

    Directory of Open Access Journals (Sweden)

    Sunhyoung eHan

    2014-09-01

    Full Text Available The benefits of integrating attention and object recognition are investigated. While attention is frequently modeled as pre-processor for recognition, we investigate the hypothesis that attention is an intrinsic component of recognition and vice-versa. This hypothesis is tested with a recognitionmodel, the hierarchical discriminant saliency network (HDSN, whose layers are top-down saliency detectors, tuned for a visual class according to the principles of discriminant saliency. The HDSN has two possible implementations. In a biologically plausible implementation, all layers comply with the standard neurophysiological model of visual cortex, with sub-layers of simple and complex units that implement a combination of filtering, divisive normalization, pooling, and non-linearities. In a neuralnetwork implementation, all layers are convolutional and implement acombination of filtering, rectification, and pooling. The rectificationis performed with a parametric extension of the now popular rectified linearunits (ReLUs, whose parameters can be tuned for the detection of targetobject classes. This enables a number of functional enhancementsover neural network models that lack a connection to saliency, including optimal feature denoising mechanisms for recognition, modulation ofsaliency responses by the discriminant power of the underlying features,and the ability to detect both feature presence and absence.In either implementation, each layer has a precise statistical interpretation, and all parameters are tuned by statistical learning. Each saliency detection layer learns more discriminant saliency templates than its predecessors and higher layers have larger pooling fields. This enables the HDSN to simultaneously achieve high selectivity totarget object classes and invariance. The resulting performance demonstrates benefits for all the functional enhancements of the HDSN.

  20. Reverse logistics - a framework

    OpenAIRE

    Brito, Marisa; Dekker, Rommert

    2002-01-01

    textabstractIn this paper we define and compare Reverse Logistics definitions. We start by giving an understanding framework of Reverse Logistics: the why-what-how. By this means, we put in context the driving forces for Reverse Logistics, a typology of return reasons, a classification of products, processes and actors. In addition we provide a decision framework for Reverse Logistics and we present it according to long, medium and short term decisions, i.e. strategic-tactic-operational decis...