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Sample records for reflexes motion perception

  1. Modification of Otolith-Ocular Reflexes, Motion Perception and Manual Control During Variable Radius Centrifugation Following Space Flight

    Science.gov (United States)

    Wood, Scott J.; Clarke, A. H.; Rupert, A. H.; Harm, D. L.; Clement, G. R.

    2009-01-01

    Two joint ESA-NASA studies are examining changes in otolith-ocular reflexes and motion perception following short duration space flights, and the operational implications of post-flight tilt-translation ambiguity for manual control performance. Vibrotactile feedback of tilt orientation is also being evaluated as a countermeasure to improve performance during a closed-loop nulling task. Data is currently being collected on astronaut subjects during 3 preflight sessions and during the first 8 days after Shuttle landings. Variable radius centrifugation is utilized to elicit otolith reflexes in the lateral plane without concordant roll canal cues. Unilateral centrifugation (400 deg/s, 3.5 cm radius) stimulates one otolith positioned off-axis while the opposite side is centered over the axis of rotation. During this paradigm, roll-tilt perception is measured using a subjective visual vertical task and ocular counter-rolling is obtained using binocular video-oculography. During a second paradigm (216 deg/s, less than 20 cm radius), the effects of stimulus frequency (0.15 - 0.6 Hz) are examined on eye movements and motion perception. A closed-loop nulling task is also performed with and without vibrotactile display feedback of chair radial position. Data collection is currently ongoing. Results to date suggest there is a trend for perceived tilt and translation amplitudes to be increased at the low and medium frequencies on landing day compared to pre-flight. Manual control performance is improved with vibrotactile feedback. One result of this study will be to characterize the variability (gain, asymmetry) in both otolith-ocular responses and motion perception during variable radius centrifugation, and measure the time course of post-flight recovery. This study will also address how adaptive changes in otolith-mediated reflexes correspond to one's ability to perform closed-loop nulling tasks following G-transitions, and whether manual control performance can be improved

  2. Modification of Otolith-Ocular Reflexes, Motion Perception and Manual Control During Variable Radius Centrifugation Following Space Flight

    Science.gov (United States)

    Wood, Scott J.; Clarke, A. H.; Rupert, A. H.; Harm, D. L.; Clement, G. R.

    2009-01-01

    Two joint ESA-NASA studies are examining changes in otolith-ocular reflexes and motion perception following short duration space flights, and the operational implications of post-flight tilt-translation ambiguity for manual control performance. Vibrotactile feedback of tilt orientation is also being evaluated as a countermeasure to improve performance during a closed-loop nulling task. Data is currently being collected on astronaut subjects during 3 preflight sessions and during the first 8 days after Shuttle landings. Variable radius centrifugation is utilized to elicit otolith reflexes in the lateral plane without concordant roll canal cues. Unilateral centrifugation (400 deg/s, 3.5 cm radius) stimulates one otolith positioned off-axis while the opposite side is centered over the axis of rotation. During this paradigm, roll-tilt perception is measured using a subjective visual vertical task and ocular counter-rolling is obtained using binocular video-oculography. During a second paradigm (216 deg/s, less than 20 cm radius), the effects of stimulus frequency (0.15 - 0.6 Hz) are examined on eye movements and motion perception. A closed-loop nulling task is also performed with and without vibrotactile display feedback of chair radial position. Data collection is currently ongoing. Results to date suggest there is a trend for perceived tilt and translation amplitudes to be increased at the low and medium frequencies on landing day compared to pre-flight. Manual control performance is improved with vibrotactile feedback. One result of this study will be to characterize the variability (gain, asymmetry) in both otolith-ocular responses and motion perception during variable radius centrifugation, and measure the time course of post-flight recovery. This study will also address how adaptive changes in otolith-mediated reflexes correspond to one's ability to perform closed-loop nulling tasks following G-transitions, and whether manual control performance can be improved

  3. Translational Vestibulo-Ocular Reflex and Motion Perception During Interaural Linear Acceleration: Comparison of Different Motion Paradigms

    Science.gov (United States)

    Beaton, K. H.; Holly, J. E.; Clement, G. R.; Wood, S. J.

    2011-01-01

    The neural mechanisms to resolve ambiguous tilt-translation motion have been hypothesized to be different for motion perception and eye movements. Previous studies have demonstrated differences in ocular and perceptual responses using a variety of motion paradigms, including Off-Vertical Axis Rotation (OVAR), Variable Radius Centrifugation (VRC), translation along a linear track, and tilt about an Earth-horizontal axis. While the linear acceleration across these motion paradigms is presumably equivalent, there are important differences in semicircular canal cues. The purpose of this study was to compare translation motion perception and horizontal slow phase velocity to quantify consistencies, or lack thereof, across four different motion paradigms. Twelve healthy subjects were exposed to sinusoidal interaural linear acceleration between 0.01 and 0.6 Hz at 1.7 m/s/s (equivalent to 10 tilt) using OVAR, VRC, roll tilt, and lateral translation. During each trial, subjects verbally reported the amount of perceived peak-to-peak lateral translation and indicated the direction of motion with a joystick. Binocular eye movements were recorded using video-oculography. In general, the gain of translation perception (ratio of reported linear displacement to equivalent linear stimulus displacement) increased with stimulus frequency, while the phase did not significantly vary. However, translation perception was more pronounced during both VRC and lateral translation involving actual translation, whereas perceptions were less consistent and more variable during OVAR and roll tilt which did not involve actual translation. For each motion paradigm, horizontal eye movements were negligible at low frequencies and showed phase lead relative to the linear stimulus. At higher frequencies, the gain of the eye movements increased and became more inphase with the acceleration stimulus. While these results are consistent with the hypothesis that the neural computational strategies for

  4. Role of cerebellum in motion perception and vestibulo-ocular reflex-similarities and disparities.

    Science.gov (United States)

    Shaikh, Aasef G; Palla, Antonella; Marti, Sarah; Olasagasti, Itsaso; Optican, Lance M; Zee, David S; Straumann, Dominik

    2013-02-01

    Vestibular velocity storage enhances the efficacy of the angular vestibulo-ocular reflex (VOR) during relatively low-frequency head rotations. This function is modulated by GABA-mediated inhibitory cerebellar projections. Velocity storage also exists in perceptual pathway and has similar functional principles as VOR. However, it is not known whether the neural substrate for perception and VOR overlap. We propose two possibilities. First, there is the same velocity storage for both VOR and perception; second, there are nonoverlapping neural networks: one might be involved in perception and the other for the VOR. We investigated these possibilities by measuring VOR and perceptual responses in healthy human subjects during whole-body, constant-velocity rotation steps about all three dimensions (yaw, pitch, and roll) before and after 10 mg of 4-aminopyridine (4-AP). 4-AP, a selective blocker of inward rectifier potassium conductance, can lead to increased synchronization and precision of Purkinje neuron discharge and possibly enhance the GABAergic action. Hence 4-AP could reduce the decay time constant of the perceived angular velocity and VOR. We found that 4-AP reduced the decay time constant, but the amount of reduction in the two processes, perception and VOR, was not the same, suggesting the possibility of nonoverlapping or partially overlapping neural substrates for VOR and perception. We also noted that, unlike the VOR, the perceived angular velocity gradually built up and plateau prior to decay. Hence, the perception pathway may have additional mechanism that changes the dynamics of perceived angular velocity beyond the velocity storage. 4-AP had no effects on the duration of build-up of perceived angular velocity, suggesting that the higher order processing of perception, beyond the velocity storage, might not occur under the influence of mechanism that could be influenced by 4-AP.

  5. Self-motion perception and vestibulo-ocular reflex during whole body yaw rotation in standing subjects: the role of head position and neck proprioception.

    Science.gov (United States)

    Panichi, Roberto; Botti, Fabio Massimo; Ferraresi, Aldo; Faralli, Mario; Kyriakareli, Artemis; Schieppati, Marco; Pettorossi, Vito Enrico

    2011-04-01

    Self-motion perception and vestibulo-ocular reflex (VOR) were studied during whole body yaw rotation in the dark at different static head positions. Rotations consisted of four cycles of symmetric sinusoidal and asymmetric oscillations. Self-motion perception was evaluated by measuring the ability of subjects to manually track a static remembered target. VOR was recorded separately and the slow phase eye position (SPEP) was computed. Three different head static yaw deviations (active and passive) relative to the trunk (0°, 45° to right and 45° to left) were examined. Active head deviations had a significant effect during asymmetric oscillation: the movement perception was enhanced when the head was kept turned toward the side of body rotation and decreased in the opposite direction. Conversely, passive head deviations had no effect on movement perception. Further, vibration (100 Hz) of the neck muscles splenius capitis and sternocleidomastoideus remarkably influenced perceived rotation during asymmetric oscillation. On the other hand, SPEP of VOR was modulated by active head deviation, but was not influenced by neck muscle vibration. Through its effects on motion perception and reflex gain, head position improved gaze stability and enhanced self-motion perception in the direction of the head deviation.

  6. ZAG-Otolith: Modification of Otolith-Ocular Reflexes, Motion Perception and Manual Control during Variable Radius Centrifugation Following Space Flight

    Science.gov (United States)

    Wood, S. J.; Clarke, A. H.; Rupert, A. H.; Harm, D. L.; Clement, G. R.

    2009-01-01

    Two joint ESA-NASA studies are examining changes in otolith-ocular reflexes and motion perception following short duration space flights, and the operational implications of post-flight tilt-translation ambiguity for manual control performance. Vibrotactile feedback of tilt orientation is also being evaluated as a countermeasure to improve performance during a closed-loop nulling task. METHODS. Data is currently being collected on astronaut subjects during 3 preflight sessions and during the first 8 days after Shuttle landings. Variable radius centrifugation is utilized to elicit otolith reflexes in the lateral plane without concordant roll canal cues. Unilateral centrifugation (400 deg/s, 3.5 cm radius) stimulates one otolith positioned off-axis while the opposite side is centered over the axis of rotation. During this paradigm, roll-tilt perception is measured using a subjective visual vertical task and ocular counter-rolling is obtained using binocular video-oculography. During a second paradigm (216 deg/s, radius), the effects of stimulus frequency (0.15 - 0.6 Hz) are examined on eye movements and motion perception. A closed-loop nulling task is also performed with and without vibrotactile display feedback of chair radial position. PRELIMINARY RESULTS. Data collection is currently ongoing. Results to date suggest there is a trend for perceived tilt and translation amplitudes to be increased at the low and medium frequencies on landing day compared to pre-flight. Manual control performance is improved with vibrotactile feedback. DISCUSSION. One result of this study will be to characterize the variability (gain, asymmetry) in both otolithocular responses and motion perception during variable radius centrifugation, and measure the time course of postflight recovery. This study will also address how adaptive changes in otolith-mediated reflexes correspond to one's ability to perform closed-loop nulling tasks following G-transitions, and whether manual control

  7. ZAG-Otolith: Modification of Otolith-Ocular Reflexes, Motion Perception and Manual Control during Variable Radius Centrifugation Following Space Flight

    Science.gov (United States)

    Wood, S. J.; Clarke, A. H.; Rupert, A. H.; Harm, D. L.; Clement, G. R.

    2009-01-01

    Two joint ESA-NASA studies are examining changes in otolith-ocular reflexes and motion perception following short duration space flights, and the operational implications of post-flight tilt-translation ambiguity for manual control performance. Vibrotactile feedback of tilt orientation is also being evaluated as a countermeasure to improve performance during a closed-loop nulling task. METHODS. Data is currently being collected on astronaut subjects during 3 preflight sessions and during the first 8 days after Shuttle landings. Variable radius centrifugation is utilized to elicit otolith reflexes in the lateral plane without concordant roll canal cues. Unilateral centrifugation (400 deg/s, 3.5 cm radius) stimulates one otolith positioned off-axis while the opposite side is centered over the axis of rotation. During this paradigm, roll-tilt perception is measured using a subjective visual vertical task and ocular counter-rolling is obtained using binocular video-oculography. During a second paradigm (216 deg/s, perception. A closed-loop nulling task is also performed with and without vibrotactile display feedback of chair radial position. PRELIMINARY RESULTS. Data collection is currently ongoing. Results to date suggest there is a trend for perceived tilt and translation amplitudes to be increased at the low and medium frequencies on landing day compared to pre-flight. Manual control performance is improved with vibrotactile feedback. DISCUSSION. One result of this study will be to characterize the variability (gain, asymmetry) in both otolithocular responses and motion perception during variable radius centrifugation, and measure the time course of postflight recovery. This study will also address how adaptive changes in otolith-mediated reflexes correspond to one's ability to perform closed-loop nulling tasks following G-transitions, and whether manual control performance can be improved with vibrotactile feedback of orientation.

  8. ZAG-Otolith: Modification of Otolith-Ocular Reflexes, Motion Perception and Manual Control during Variable Radius Centrifugation Following Space Flight

    Science.gov (United States)

    Wood, S. J.; Clarke, A. H.; Rupert, A. H.; Harm, D. L.; Clement, G. R.

    2009-01-01

    Two joint ESA-NASA studies are examining changes in otolith-ocular reflexes and motion perception following short duration space flights, and the operational implications of post-flight tilt-translation ambiguity for manual control performance. Vibrotactile feedback of tilt orientation is also being evaluated as a countermeasure to improve performance during a closed-loop nulling task. METHODS. Data is currently being collected on astronaut subjects during 3 preflight sessions and during the first 8 days after Shuttle landings. Variable radius centrifugation is utilized to elicit otolith reflexes in the lateral plane without concordant roll canal cues. Unilateral centrifugation (400 deg/s, 3.5 cm radius) stimulates one otolith positioned off-axis while the opposite side is centered over the axis of rotation. During this paradigm, roll-tilt perception is measured using a subjective visual vertical task and ocular counter-rolling is obtained using binocular video-oculography. During a second paradigm (216 deg/s, reflexes correspond to one's ability to perform closed-loop nulling tasks following G-transitions, and whether manual control performance can be improved with vibrotactile feedback of orientation.

  9. Biological Motion Cues Trigger Reflexive Attentional Orienting

    Science.gov (United States)

    Shi, Jinfu; Weng, Xuchu; He, Sheng; Jiang, Yi

    2010-01-01

    The human visual system is extremely sensitive to biological signals around us. In the current study, we demonstrate that biological motion walking direction can induce robust reflexive attentional orienting. Following a brief presentation of a central point-light walker walking towards either the left or right direction, observers' performance…

  10. Neural Basis of Motion Perception

    Science.gov (United States)

    1992-05-31

    Oxford University, England. 11. Interviewed on BBC television ("Antenna"). Debate with Daniel C. Dennett . Aired on August 8, 1992. 12. Interviewed on PBS...integrated approach to vision. We have had two goals in mind: (1) To develoN~onceptual links between neurophysiology and perception ; (2) Fo develop specific...range of new "natural constraints" that govern the perception of shape-from shading structure from motion and motion correspondence. Also, we have

  11. Pupillary Reflex and Saccade in Bistable Perception to Ambiguous Figure of Stucture-from-Motion%动态歧义图知觉中的瞳孔反射和眼动扫视行为

    Institute of Scientific and Technical Information of China (English)

    谭恒; 王毅

    2014-01-01

    歧义图的双稳态知觉是一种非常有趣的视觉现象,但对其机制还不十分清楚.采用“运动产生的结构”(structurefrom-motion)的歧义图和无歧义的对照图,我们研究了这一问题.被试者在报告对歧义图和无歧义图的知觉发生翻转时,其瞳孔都扩张,而且在翻转之后都达到峰值;与无歧义图条件下不同,在报告知觉翻转前,歧义图条件下的瞳孔要明显小于均值,而在瞳孔扩张达到峰值之后,瞳孔仍然明显大于均值.这些结果说明知觉翻转后的瞳孔扩张是一个表达被试知觉状态己改变的指标.而对歧义图和无歧义图刺激的瞳孔反射的差异,可能反映了由歧义图所产生知觉翻转的神经信号和知觉状态的内源性.另外,被试眼动扫视的方向会随着运动轴的变化呈现不同的扫视分布模式,但在歧义图与无歧义图之间分布模式是一致的,这不仅表明被试从歧义图中感知到了与无歧义图同样的信息,也表明瞳孔反射变化与双稳态知觉变化相关的结论具有可靠性.本文对歧义图双稳态知觉的视觉机制提供了新的认识.%Bistable perception to ambiguous figure is an intriguing visual phenomenon.The underlying mechanisms,however,remain largely unclear.We addressed the issue by recording eye saccade and pupillary reflex in the perceptual responses of human subjects to the ambiguous figure and disambiguous figure (control) generated from the structure-from-motion stimuli.Their pupils dilated when the subjects reported the perceptual reversal between the two mutually exclusive states to both the ambiguous figure and disambiguous figure.The pupillary dilation reached the peak after the perceptual reversal.In contrast to the disambiguous figure,before reported the reversal to the ambiguous figure,the pupils were smaller than the mean size,while after the peak of pupillary dilation occurred,the pupils were still larger than the mean size.These results

  12. The effect of distraction strategies on pain perception and the nociceptive flexor reflex (RIII reflex).

    Science.gov (United States)

    Ruscheweyh, Ruth; Kreusch, Annette; Albers, Christoph; Sommer, Jens; Marziniak, Martin

    2011-11-01

    Distraction from pain reduces pain perception, and imaging studies have suggested that this may at least partially be mediated by activation of descending pain inhibitory systems. Here, we used the nociceptive flexor reflex (RIII reflex) to directly quantify the effects of different distraction strategies on basal spinal nociception and its temporal summation. Twenty-seven healthy subjects participated in 3 distraction tasks (mental imagery, listening to preferred music, spatial discrimination of brush stimuli) and, in a fourth task, concentrated on the painful stimulus. Results show that all 3 distraction tasks reduced pain perception, but only the brush task also reduced the RIII reflex. The concentration-on-pain task increased both pain perception and the RIII reflex. The extent of temporal summation of pain perception and the extent of temporal summation of the RIII reflex were not affected by any of the tasks. These results suggest that some, but not all, forms of pain reduction by distraction rely on descending pain inhibition. In addition, pain reduction by distraction seems to preferentially affect mechanisms of basal nociceptive transmission, not of temporal summation. Copyright © 2011 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

  13. Biological Motion Perception in Autism

    Directory of Open Access Journals (Sweden)

    J Cusack

    2011-04-01

    Full Text Available Typically developing adults can readily recognize human actions, even when conveyed to them via point-like markers placed on the body of the actor (Johansson, 1973. Previous research has suggested that children affected by autism spectrum disorder (ASD are not equally sensitive to this type of visual information (Blake et al, 2003, but it remains unknown why ASD would impact the ability to perceive biological motion. We present evidence which looks at how adolescents and adults with autism are affected by specific factors which are important in biological motion perception, such as (eg, inter-agent synchronicity, upright/inverted, etc.

  14. Biological motion distorts size perception

    Science.gov (United States)

    Veto, Peter; Einhäuser, Wolfgang; Troje, Nikolaus F.

    2017-02-01

    Visual illusions explore the limits of sensory processing and provide an ideal testbed to study perception. Size illusions - stimuli whose size is consistently misperceived - do not only result from sensory cues, but can also be induced by cognitive factors, such as social status. Here we investigate, whether the ecological relevance of biological motion can also distort perceived size. We asked observers to judge the size of point-light walkers (PLWs), configurations of dots whose movements induce the perception of human movement, and visually matched control stimuli (inverted PLWs). We find that upright PLWs are consistently judged as larger than inverted PLWs, while static point-light figures do not elicit the same effect. We also show the phenomenon using an indirect paradigm: observers judged the relative size of a disc that followed an inverted PLW larger than a disc following an upright PLW. We interpret this as a contrast effect: The upright PLW is perceived larger and thus the subsequent disc is judged smaller. Together, these results demonstrate that ecologically relevant biological-motion stimuli are perceived larger than visually matched control stimuli. Our findings present a novel case of illusory size perception, where ecological importance leads to a distorted perception of size.

  15. Biological motion distorts size perception

    Science.gov (United States)

    Veto, Peter; Einhäuser, Wolfgang; Troje, Nikolaus F.

    2017-01-01

    Visual illusions explore the limits of sensory processing and provide an ideal testbed to study perception. Size illusions – stimuli whose size is consistently misperceived – do not only result from sensory cues, but can also be induced by cognitive factors, such as social status. Here we investigate, whether the ecological relevance of biological motion can also distort perceived size. We asked observers to judge the size of point-light walkers (PLWs), configurations of dots whose movements induce the perception of human movement, and visually matched control stimuli (inverted PLWs). We find that upright PLWs are consistently judged as larger than inverted PLWs, while static point-light figures do not elicit the same effect. We also show the phenomenon using an indirect paradigm: observers judged the relative size of a disc that followed an inverted PLW larger than a disc following an upright PLW. We interpret this as a contrast effect: The upright PLW is perceived larger and thus the subsequent disc is judged smaller. Together, these results demonstrate that ecologically relevant biological-motion stimuli are perceived larger than visually matched control stimuli. Our findings present a novel case of illusory size perception, where ecological importance leads to a distorted perception of size. PMID:28205639

  16. Human motion perception: Higher-order organization

    Science.gov (United States)

    Kaiser, Mary K.; Proffitt, Dennis R.

    1990-01-01

    An overview is given of higher-order motion perception and organization. It is argued that motion is sufficient to fully specify a number of environmental properties, including: depth order, three-dimensional form, object displacement, and dynamics. A grammar of motion perception is proposed; applications of this work for display design are discussed.

  17. Perception of biological motion in visual agnosia.

    Science.gov (United States)

    Huberle, Elisabeth; Rupek, Paul; Lappe, Markus; Karnath, Hans-Otto

    2012-01-01

    Over the past 25 years, visual processing has been discussed in the context of the dual stream hypothesis consisting of a ventral ("what") and a dorsal ("where") visual information processing pathway. Patients with brain damage of the ventral pathway typically present with signs of visual agnosia, the inability to identify and discriminate objects by visual exploration, but show normal perception of motion perception. A dissociation between the perception of biological motion and non-biological motion has been suggested: perception of biological motion might be impaired when "non-biological" motion perception is intact and vice versa. The impact of object recognition on the perception of biological motion remains unclear. We thus investigated this question in a patient with severe visual agnosia, who showed normal perception of non-biological motion. The data suggested that the patient's perception of biological motion remained largely intact. However, when tested with objects constructed of coherently moving dots ("Shape-from-Motion"), recognition was severely impaired. The results are discussed in the context of possible mechanisms of biological motion perception.

  18. Perception of biological motion in visual agnosia

    Directory of Open Access Journals (Sweden)

    Elisabeth eHuberle

    2012-08-01

    Full Text Available Over the past twenty-five years, visual processing has been discussed in the context of the dual stream hypothesis consisting of a ventral (‘what' and a dorsal ('where' visual information processing pathway. Patients with brain damage of the ventral pathway typically present with signs of visual agnosia, the inability to identify and discriminate objects by visual exploration, but show normal perception of motion perception. A dissociation between the perception of biological motion and non-biological motion has been suggested: Perception of biological motion might be impaired when 'non-biological' motion perception is intact and vice versa. The impact of object recognition on the perception of biological motion remains unclear. We thus investigated this question in a patient with severe visual agnosia, who showed normal perception of non-biological motion. The data suggested that the patient's perception of biological motion remained largely intact. However, when tested with objects constructed of coherently moving dots (‘Shape-from-Motion’, recognition was severely impaired. The results are discussed in the context of possible mechanisms of biological motion perception.

  19. Visual-vestibular interaction in motion perception

    NARCIS (Netherlands)

    Hosman, R.J.A.W.; Cardullo, F.M.; Bos, J.E.

    2011-01-01

    Correct perception of self motion is of vital importance for both the control of our position and posture when moving around in our environment. With the development of human controlled vehicles as bicycles, cars and aircraft motion perception became of interest for the understanding of vehicle

  20. Visual-vestibular interaction in motion perception

    NARCIS (Netherlands)

    Hosman, R.J.A.W.; Cardullo, F.M.; Bos, J.E.

    2011-01-01

    Correct perception of self motion is of vital importance for both the control of our position and posture when moving around in our environment. With the development of human controlled vehicles as bicycles, cars and aircraft motion perception became of interest for the understanding of vehicle cont

  1. Perception of biological motion in visual agnosia

    OpenAIRE

    Elisabeth eHuberle; Paul eRupek; Markus eLappe; Hans-Otto eKarnath

    2012-01-01

    Over the past twenty-five years, visual processing has been discussed in the context of the dual stream hypothesis consisting of a ventral (‘what') and a dorsal ('where') visual information processing pathway. Patients with brain damage of the ventral pathway typically present with signs of visual agnosia, the inability to identify and discriminate objects by visual exploration, but show normal perception of motion perception. A dissociation between the perception of biological motion and non...

  2. Ambiguity in Tactile Apparent Motion Perception

    OpenAIRE

    Emanuela Liaci; Michael Bach; Ludger Tebartz Van Elst; Heinrich, Sven P; Jürgen Kornmeier

    2016-01-01

    Background In von Schiller’s Stroboscopic Alternative Motion (SAM) stimulus two visually presented diagonal dot pairs, located on the corners of an imaginary rectangle, alternate with each other and induce either horizontal, vertical or, rarely, rotational motion percepts. SAM motion perception can be described by a psychometric function of the dot aspect ratio (“AR”, i.e. the relation between vertical and horizontal dot distances). Further, with equal horizontal and vertical dot distances (A...

  3. The perception of object versus objectless motion.

    Science.gov (United States)

    Hock, Howard S; Nichols, David F

    2013-05-01

    Wertheimer, M. (Zeitschrift für Psychologie und Physiologie der Sinnesorgane, 61:161-265, 1912) classical distinction between beta (object) and phi (objectless) motion is elaborated here in a series of experiments concerning competition between two qualitatively different motion percepts, induced by sequential changes in luminance for two-dimensional geometric objects composed of rectangular surfaces. One of these percepts is of spreading-luminance motion that continuously sweeps across the entire object; it exhibits shape invariance and is perceived most strongly for fast speeds. Significantly for the characterization of phi as objectless motion, the spreading luminance does not involve surface boundaries or any other feature; the percept is driven solely by spatiotemporal changes in luminance. Alternatively, and for relatively slow speeds, a discrete series of edge motions can be perceived in the direction opposite to spreading-luminance motion. Akin to beta motion, the edges appear to move through intermediate positions within the object's changing surfaces. Significantly for the characterization of beta as object motion, edge motion exhibits shape dependence and is based on the detection of oppositely signed changes in contrast (i.e., counterchange) for features essential to the determination of an object's shape, the boundaries separating its surfaces. These results are consistent with area MT neurons that differ with respect to speed preference Newsome et al (Journal of Neurophysiology, 55:1340-1351, 1986) and shape dependence Zeki (Journal of Physiology, 236:549-573, 1974).

  4. Ambiguity in Tactile Apparent Motion Perception.

    Directory of Open Access Journals (Sweden)

    Emanuela Liaci

    Full Text Available In von Schiller's Stroboscopic Alternative Motion (SAM stimulus two visually presented diagonal dot pairs, located on the corners of an imaginary rectangle, alternate with each other and induce either horizontal, vertical or, rarely, rotational motion percepts. SAM motion perception can be described by a psychometric function of the dot aspect ratio ("AR", i.e. the relation between vertical and horizontal dot distances. Further, with equal horizontal and vertical dot distances (AR = 1 perception is biased towards vertical motion. In a series of five experiments, we presented tactile SAM versions and studied the role of AR and of different reference frames for the perception of tactile apparent motion.We presented tactile SAM stimuli and varied the ARs, while participants reported the perceived motion directions. Pairs of vibration stimulators were attached to the participants' forearms and stimulator distances were varied within and between forearms. We compared straight and rotated forearm conditions with each other in order to disentangle the roles of exogenous and endogenous reference frames.Increasing the tactile SAM's AR biased perception towards vertical motion, but the effect was weak compared to the visual modality. We found no horizontal disambiguation, even for very small tactile ARs. A forearm rotation by 90° kept the vertical bias, even though it was now coupled with small ARs. A 45° rotation condition with crossed forearms, however, evoked a strong horizontal motion bias.Existing approaches to explain the visual SAM bias fail to explain the current tactile results. Particularly puzzling is the strong horizontal bias in the crossed-forearm conditions. In the case of tactile apparent motion, there seem to be no fixed priority rule for perceptual disambiguation. Rather the weighting of available evidence seems to depend on the degree of stimulus ambiguity, the current situation and on the perceptual strategy of the individual

  5. The neural basis of tactile motion perception.

    Science.gov (United States)

    Pei, Yu-Cheng; Bensmaia, Sliman J

    2014-12-15

    The manipulation of objects commonly involves motion between object and skin. In this review, we discuss the neural basis of tactile motion perception and its similarities with its visual counterpart. First, much like in vision, the perception of tactile motion relies on the processing of spatiotemporal patterns of activation across populations of sensory receptors. Second, many neurons in primary somatosensory cortex are highly sensitive to motion direction, and the response properties of these neurons draw strong analogies to those of direction-selective neurons in visual cortex. Third, tactile speed may be encoded in the strength of the response of cutaneous mechanoreceptive afferents and of a subpopulation of speed-sensitive neurons in cortex. However, both afferent and cortical responses are strongly dependent on texture as well, so it is unclear how texture and speed signals are disambiguated. Fourth, motion signals from multiple fingers must often be integrated during the exploration of objects, but the way these signals are combined is complex and remains to be elucidated. Finally, visual and tactile motion perception interact powerfully, an integration process that is likely mediated by visual association cortex.

  6. sEMG during Whole-Body Vibration Contains Motion Artifacts and Reflex Activity

    Directory of Open Access Journals (Sweden)

    Karin Lienhard

    2015-01-01

    Full Text Available The purpose of this study was to determine whether the excessive spikes observed in the surface electromyography (sEMG spectrum recorded during whole-body vibration (WBV exercises contain motion artifacts and/or reflex activity. The occurrence of motion artifacts was tested by electrical recordings of the patella. The involvement of reflex activity was investigated by analyzing the magnitude of the isolated spikes during changes in voluntary background muscle activity. Eighteen physically active volunteers performed static squats while the sEMG was measured of five lower limb muscles during vertical WBV using no load and an additional load of 33 kg. In order to record motion artifacts during WBV, a pair of electrodes was positioned on the patella with several layers of tape between skin and electrodes. Spectral analysis of the patella signal revealed recordings of motion artifacts as high peaks at the vibration frequency (fundamental and marginal peaks at the multiple harmonics were observed. For the sEMG recordings, the root mean square of the spikes increased with increasing additional loads (p < 0.05, and was significantly correlated to the sEMG signal without the spikes of the respective muscle (r range: 0.54 - 0.92, p < 0.05. This finding indicates that reflex activity might be contained in the isolated spikes, as identical behavior has been found for stretch reflex responses evoked during direct vibration. In conclusion, the spikes visible in the sEMG spectrum during WBV exercises contain motion artifacts and possibly reflex activity.

  7. Neural Network Approaches to Visual Motion Perception

    Institute of Scientific and Technical Information of China (English)

    郭爱克; 杨先一

    1994-01-01

    This paper concerns certain difficult problems in image processing and perception: neuro-computation of visual motion information. The first part of this paper deals with the spatial physiological integration by the figure-ground discrimination neural network in the visual system of the fly. We have outlined the fundamental organization and algorithms of this neural network, and mainly concentrated on the results of computer simulations of spatial physiological integration. It has been shown that the gain control mechanism , the nonlinearity of synaptic transmission characteristic , the interaction between the two eyes , and the directional selectivity of the pool cells play decisive roles in the spatial physiological integration. In the second part, we have presented a self-organizing neural network for the perception of visual motion by using a retinotopic array of Reichardt’s motion detectors and Kohonen’s self-organizing maps. It .has been demonstrated by computer simulations that the network is abl

  8. The Effect of Whole Body Vibration on Ankle Range of Motion and the H-reflex.

    Science.gov (United States)

    Apple, Stacey; Ehlert, Kelly; Hysinger, Pam; Nash, Cara; Voight, Michael; Sells, Pat

    2010-02-01

    Limited research suggests that an effect of whole body vibration (WBV) on the central nervous system (CNS) is suppression. An indirect measure used to assess CNS level of activation is the Soleus H-reflex. If true suppression does occur, other factors such as range of motion may be impacted. The purpose of this study was to examine the impact of WBV on H-reflex amplitude and passive ankle dorsiflexion. Twenty-seven healthy volunteers between the ages of 21-41 participated. Subjects were randomly assigned to a control group (n=13) or WBV group (n=14). H-reflex and ankle dorsiflexion measures were assessed before and after a three minute WBV perturbation (40 μHz, amplitude 2-4 mm). These measurements were repeated every five minutes up to twenty minutes following the intervention. The H-reflex amplitude showed a significant decrease (pmotion showed significant interaction (pcontrol group also showed this change, WBV does not appear to be a key cause of suppression. Range of motion was not clinically significant for either group.

  9. The role of human ventral visual cortex in motion perception.

    Science.gov (United States)

    Gilaie-Dotan, Sharon; Saygin, Ayse P; Lorenzi, Lauren J; Egan, Ryan; Rees, Geraint; Behrmann, Marlene

    2013-09-01

    Visual motion perception is fundamental to many aspects of visual perception. Visual motion perception has long been associated with the dorsal (parietal) pathway and the involvement of the ventral 'form' (temporal) visual pathway has not been considered critical for normal motion perception. Here, we evaluated this view by examining whether circumscribed damage to ventral visual cortex impaired motion perception. The perception of motion in basic, non-form tasks (motion coherence and motion detection) and complex structure-from-motion, for a wide range of motion speeds, all centrally displayed, was assessed in five patients with a circumscribed lesion to either the right or left ventral visual pathway. Patients with a right, but not with a left, ventral visual lesion displayed widespread impairments in central motion perception even for non-form motion, for both slow and for fast speeds, and this held true independent of the integrity of areas MT/V5, V3A or parietal regions. In contrast with the traditional view in which only the dorsal visual stream is critical for motion perception, these novel findings implicate a more distributed circuit in which the integrity of the right ventral visual pathway is also necessary even for the perception of non-form motion.

  10. Human Perception of Ambiguous Inertial Motion Cues

    Science.gov (United States)

    Zhang, Guan-Lu

    2010-01-01

    Human daily activities on Earth involve motions that elicit both tilt and translation components of the head (i.e. gazing and locomotion). With otolith cues alone, tilt and translation can be ambiguous since both motions can potentially displace the otolithic membrane by the same magnitude and direction. Transitions between gravity environments (i.e. Earth, microgravity and lunar) have demonstrated to alter the functions of the vestibular system and exacerbate the ambiguity between tilt and translational motion cues. Symptoms of motion sickness and spatial disorientation can impair human performances during critical mission phases. Specifically, Space Shuttle landing records show that particular cases of tilt-translation illusions have impaired the performance of seasoned commanders. This sensorimotor condition is one of many operational risks that may have dire implications on future human space exploration missions. The neural strategy with which the human central nervous system distinguishes ambiguous inertial motion cues remains the subject of intense research. A prevailing theory in the neuroscience field proposes that the human brain is able to formulate a neural internal model of ambiguous motion cues such that tilt and translation components can be perceptually decomposed in order to elicit the appropriate bodily response. The present work uses this theory, known as the GIF resolution hypothesis, as the framework for experimental hypothesis. Specifically, two novel motion paradigms are employed to validate the neural capacity of ambiguous inertial motion decomposition in ground-based human subjects. The experimental setup involves the Tilt-Translation Sled at Neuroscience Laboratory of NASA JSC. This two degree-of-freedom motion system is able to tilt subjects in the pitch plane and translate the subject along the fore-aft axis. Perception data will be gathered through subject verbal reports. Preliminary analysis of perceptual data does not indicate that

  11. The vestibulo-ocular reflex and its possible roles in space motion sickness

    Science.gov (United States)

    Watt, Douglas G. D.

    1987-01-01

    Prolonged exposure to an inappropriate vestibulo-ocular reflex (VOR) will usually lead to motion sickness, and it has been predicted on theoretical grounds that VOR gain may be decreased in weightlessness. While experiments during parabolic flight in aircraft tend to confirm this prediction, experiments during orbital spaceflight have led to apparently contradictory results. It is suggested that VOR gain is reduced initially, but that rapid compensatory mechanisms restore it to normal within minutes of reaching weightlessness. However, even though this process may lead to the rapid return of functionally normal gaze stability, it may not protect against the development of motion sickness.

  12. Perception of illusory contours enhanced in motion

    Institute of Scientific and Technical Information of China (English)

    倪睿; 王志宏; 吴新年; 汪云九; 李东光

    2003-01-01

    Investigation on illusory contours is important for understanding the mechanisms un-derlying the object recognition of human visual system. Numerous researches have shown that illusory contours formed in motion and stereopsis are generated by the unmatched features. Here we conduct three psychophysical experiments to test if Kanizsa illusory contours are also caused by unmatched information. Different types of motion (including horizontal translation, radial ex-panding and shrinking) are utilized in the experiments. The results show that no matter under what kind of motion, when figures or background move separately illusory contours are perceived stronger, and there is no significant difference between the perceived strength in these two types of motion. However, no such enhancement of perceived strength is found when figures and background move together. It is found that the strengthened unmatched features generate the enhancement effect of illusory contour perception in motion. Thus the results suggest that the process of unmatched information in visual system is a critical step in the formation of illusory contours.

  13. Abraham Guz memorial: Still unresolved hypotheses: Lung reflexes and perceptions of breathing.

    Science.gov (United States)

    Noble, Mark I M

    2015-10-01

    This article constitutes a review of the studies performed by the group of the late A. Guz and other authors on the subjects of lung reflexes and perceptions of respiration. The experimental data suggest that the lung inflation and deflation reflexes are present in man, mediated by large myelinated afferent nerve fibres in the vagus nerves, but that the inflation reflex is weaker than in animals, possibly due to central neuronal inhibition. The authors of animal results on the deflation reflex differ as to the afferent fibres involved in the vagi, but it is argued, on the basis of the data, that the preferred hypothesis is that increased activity of the large myelinated mediates the inflation reflex, and decreased activity in these same fibres mediates the deflation reflex. Smaller myelinated fibres are thought to mediate cough and increased breathing in response to airway irritation, while small non-myelinated C fibres mediate hyperpnoea in response to parenchymal congestion and various disease states. The unpleasant sensation at the break point of breath-holding is not chemically mediated but may depend on a complex response involving vagal afferent, phrenic efferent and phrenic afferent pathways. Other experiments in humans on perception of various unpleasant respiratory sensations are discussed with unclear conclusions. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Touch-contingent visual motion perception: tactile events drive visual motion perception.

    Science.gov (United States)

    Teraoka, Ryo; Teramoto, Wataru

    2017-03-01

    It has recently been demonstrated that the brain rapidly forms an association between concurrently presented sound sequences and visual motion. Once this association has been formed, the associated sound sequence can drive visual motion perception. This phenomenon is known as "sound-contingent visual motion perception" (SCVM). In the present study, we addressed the possibility of a similar association involving touch instead of audition. In a 9-min exposure session, two circles placed side by side were alternately presented to produce apparent motion in a horizontal direction. The onsets of the circle presentations were synchronized with vibrotactile stimulation on two different positions of the forearm. We then quantified pre- and post-exposure perceptual changes using a motion-nulling procedure. Results showed that after prolonged exposure to visuotactile stimuli, the tactile sequence influenced visual motion perception. Notably, this effect was specific to the previously exposed visual field, thus ruling out the possibility of simple response bias. These findings suggest that SCVM-like associations occur, at least to some extent, for the other modality combinations. Furthermore, the effect did not occur when the forearm posture was changed between the exposure and test phases, suggesting that the association is formed after integrating proprioceptive information.

  15. Deficient Biological Motion Perception in Schizophrenia: Results from a Motion Noise Paradigm

    Directory of Open Access Journals (Sweden)

    Jejoong eKim

    2013-07-01

    Full Text Available Background: Schizophrenia patients exhibit deficient processing of perceptual and cognitive information. However, it is not well understood how basic perceptual deficits contribute to higher level cognitive problems in this mental disorder. Perception of biological motion, a motion-based cognitive recognition task, relies on both basic visual motion processing and social cognitive processing, thus providing a useful paradigm to evaluate the potentially hierarchical relationship between these two levels of information processing. Methods: In this study, we designed a biological motion paradigm in which basic visual motion signals were manipulated systematically by incorporating different levels of motion noise. We measured the performances of schizophrenia patients (n=21 and healthy controls (n=22 in this biological motion perception task, as well as in coherent motion detection, theory of mind, and a widely used biological motion recognition task. Results: Schizophrenia patients performed the biological motion perception task with significantly lower accuracy than healthy controls when perceptual signals were moderately degraded by noise. A more substantial degradation of perceptual signals, through using additional noise, impaired biological motion perception in both groups. Performance levels on biological motion recognition, coherent motion detection and theory of mind tasks were also reduced in patients. Conclusion: The results from the motion-noise biological motion paradigm indicate that in the presence of visual motion noise, the processing of biological motion information in schizophrenia is deficient. Combined with the results of poor basic visual motion perception (coherent motion task and biological motion recognition, the association between basic motion signals and biological motion perception suggests a need to incorporate the improvement of visual motion perception in social cognitive remediation.

  16. Modeling human perceptual thresholds in self-motion perception

    NARCIS (Netherlands)

    Valente Pais, A.R.; Mulder, M.; Paassen, M.M. van; Wentink, M.; Groen, E.L.

    2006-01-01

    Knowledge of thresholds for perception of inertial motion is needed for the design of simulator motion filters. Experiments have generally been done to measure these thresholds in isolation, one motion at the time. In vehicle simulation however, several motions occur concurrently. In a flight

  17. Modulation of Motion Perception of Ipsilateral Tactile Stimuli Using Sound

    Directory of Open Access Journals (Sweden)

    Yuika Suzuki

    2011-10-01

    Full Text Available We report the modulation of tactile motion perception by presenting static sounds with two alternately and repeatedly presented vibrotactile stimuli for the perception of tactile apparent motion. Previous research on tactile motion perception has used direction judgment tasks for apparent motion that consist of two non-repeating, or more than two repeating stimuli. However, the direction of two repeating apparent motion stimuli has been considered too ambiguous to be judged. The present study shows that the additional presentation of sounds with manipulated timings could help to determine the perceived direction of tactile motion despite the ambiguity in the interpretation of tactile stimuli at ipsilateral locations. Furthermore, we found that there is a limited alternation rate for tactile stimuli that can be used to achieve significant modulation using sound. We relate the temporal properties observed during crossmodal effects in tactile motion perception, to those observed during some other crossmodal phenomena.

  18. IQ Predicts Biological Motion Perception in Autism Spectrum Disorders

    Science.gov (United States)

    Rutherford, M. D.; Troje, Nikolaus F.

    2012-01-01

    Biological motion is easily perceived by neurotypical observers when encoded in point-light displays. Some but not all relevant research shows significant deficits in biological motion perception among those with ASD, especially with respect to emotional displays. We tested adults with and without ASD on the perception of masked biological motion…

  19. Motion perception deficit in Down Syndrome.

    Science.gov (United States)

    Del Viva, Maria Michela; Tozzi, Arianna; Bargagna, Stefania; Cioni, Giovanni

    2015-08-01

    It is a well established fact that Down Syndrome (DS) individuals have a tendency to develop Alzheimer's disease (AD) (Lott, I.T., Head, E., 2005. Alzheimer disease and Down syndrome: factors in pathogenesis. Neurobiol. Aging 26, 383-389). They have therefore been proposed as a model to study the pre-dementia stage of Alzheimer's (Mann, D.M., 1988. The pathological association between Down syndrome and Alzheimer disease. Mech. Ageing Dev. 43, 99-136). One of the specific deficits exhibited by AD patients is optic flow motion perception (Tetewsky, S.J., Duffy, C.J., 1999. Visual loss and getting lost in Alzheimer's disease. Neurology 52, 958-965), but there are no corresponding systematic studies in DS individuals. We performed sensitivity measurements to optic flow with Visual Evoked Potentials (VEP) and psychophysical techniques in a group of young DS participants with mild mental retardation and without significant Alzheimer's clinical symptoms. We found a significant reduction in direction discrimination sensitivity to optic flow (random dots moving in radial, rotational and translational trajectories) in DS participants compared to mental age-matched controls, while their sensitivity to direction of control moving stimuli (sinusoidal gratings) was similar to age-matched controls. Measurements of Visual Evoked Potentials (VEP) showed no response to optic flow, although the response to control stimuli (contrast-reversal checkerboard patterns) was significant. Overall, our results show a selective and substantial deficit in the perception of optic flow motion and a corresponding suppression of electroencephalographic activity in DS individuals, thus establishing a further common trait between Down Syndrome and Alzheimer's disease.

  20. Illusionary self-motion perception in zebrafish.

    Directory of Open Access Journals (Sweden)

    Ying-Yu Huang

    Full Text Available Zebrafish mutant belladonna (bel carries a mutation in the lhx2 gene (encoding a Lim domain homeobox transcription factor that results in a defect in retinotectal axon pathfinding, which can lead to uncrossed optic nerves failing to form an optic chiasm. Here, we report on a novel swimming behavior of the bel mutants, best described as looping. Together with two previously reported oculomotor instabilities that have been related to achiasmatic bel mutants, reversed optokinetic response (OKR and congenital nystagmus (CN, involuntary conjugate oscillations of both eyes, looping opens a door to study the influence of visual input and eye movements on postural balance. Our result shows that looping correlates perfectly with reversed OKR and CN and is vision-dependent and contrast sensitive. CN precedes looping and the direction of the CN slow phase is predictive of the looping direction, but is absent during looping. Therefore, looping may be triggered by CN in bel. Moreover, looping in wild-type fish can also be evoked by whole-field motion, suggesting that looping in a bel mutant larvae is a result of self-motion perception. In contrary to previous hypotheses, our findings indicate that postural control in vertebrates relies on both direct visual input (afference signal and eye-movement-related signals (efference copy or reafference signal.

  1. Particularity and Reflexivity in the Intentional Content of Perception

    Directory of Open Access Journals (Sweden)

    Olga FERNÁNDEZ PRAT

    2010-01-01

    Full Text Available A significant part of perception is characterized by awareness of particular objects. Two ways of making precise this intuition have been proposed (Searle vs. Evans, Campbell and others. The dispute’s argumentative context is reconstructed and a proposal is advanced that may be regarded as a compromise between the contenders.

  2. Temporal characteristics of neuronal sources for implied motion perception

    NARCIS (Netherlands)

    Lorteije, J.A.M.; Kenemans, J.L.; Jellema, T.; Lubbe, R.H.J. van der; Heer, F. de; Wezel, R.J.A. van

    2004-01-01

    Viewing photographs of objects in motion evokes higher fMRI activation in human MT+ than similar photographs without this implied motion. MT+ is traditionally considered to be involved in motion perception. Therefore, this finding suggests feedback from object-recognition areas to MT+. To investigat

  3. Direct Contribution of Auditory Motion Information to Sound-Induced Visual Motion Perception

    Directory of Open Access Journals (Sweden)

    Souta Hidaka

    2011-10-01

    Full Text Available We have recently demonstrated that alternating left-right sound sources induce motion perception to static visual stimuli along the horizontal plane (SIVM: sound-induced visual motion perception, Hidaka et al., 2009. The aim of the current study was to elucidate whether auditory motion signals, rather than auditory positional signals, can directly contribute to the SIVM. We presented static visual flashes at retinal locations outside the fovea together with a lateral auditory motion provided by a virtual stereo noise source smoothly shifting in the horizontal plane. The flashes appeared to move in the situation where auditory positional information would have little influence on the perceived position of visual stimuli; the spatiotemporal position of the flashes was in the middle of the auditory motion trajectory. Furthermore, the auditory motion altered visual motion perception in a global motion display; in this display, different localized motion signals of multiple visual stimuli were combined to produce a coherent visual motion perception so that there was no clear one-to-one correspondence between the auditory stimuli and each visual stimulus. These findings suggest the existence of direct interactions between the auditory and visual modalities in motion processing and motion perception.

  4. Sustained Rhythmic Brain Activity Underlies Visual Motion Perception in Zebrafish

    Directory of Open Access Journals (Sweden)

    Verónica Pérez-Schuster

    2016-10-01

    Full Text Available Following moving visual stimuli (conditioning stimuli, CS, many organisms perceive, in the absence of physical stimuli, illusory motion in the opposite direction. This phenomenon is known as the motion aftereffect (MAE. Here, we use MAE as a tool to study the neuronal basis of visual motion perception in zebrafish larvae. Using zebrafish eye movements as an indicator of visual motion perception, we find that larvae perceive MAE. Blocking eye movements using optogenetics during CS presentation did not affect MAE, but tectal ablation significantly weakened it. Using two-photon calcium imaging of behaving GCaMP3 larvae, we find post-stimulation sustained rhythmic activity among direction-selective tectal neurons associated with the perception of MAE. In addition, tectal neurons tuned to the CS direction habituated, but neurons in the retina did not. Finally, a model based on competition between direction-selective neurons reproduced MAE, suggesting a neuronal circuit capable of generating perception of visual motion.

  5. Smelling directions: olfaction modulates ambiguous visual motion perception.

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    Kuang, Shenbing; Zhang, Tao

    2014-07-23

    Senses of smells are often accompanied by simultaneous visual sensations. Previous studies have documented enhanced olfactory performance with concurrent presence of congruent color- or shape- related visual cues, and facilitated visual object perception when congruent smells are simultaneously present. These visual object-olfaction interactions suggest the existences of couplings between the olfactory pathway and the visual ventral processing stream. However, it is not known if olfaction can modulate visual motion perception, a function that is related to the visual dorsal stream. We tested this possibility by examining the influence of olfactory cues on the perceptions of ambiguous visual motion signals. We showed that, after introducing an association between motion directions and olfactory cues, olfaction could indeed bias ambiguous visual motion perceptions. Our result that olfaction modulates visual motion processing adds to the current knowledge of cross-modal interactions and implies a possible functional linkage between the olfactory system and the visual dorsal pathway.

  6. Continuous perception of motion and shape across saccadic eye movements.

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    Fracasso, Alessio; Caramazza, Alfonso; Melcher, David

    2010-11-24

    Although our naïve experience of visual perception is that it is smooth and coherent, the actual input from the retina involves brief and discrete fixations separated by saccadic eye movements. This raises the question of whether our impression of stable and continuous vision is merely an illusion. To test this, we examined whether motion perception can "bridge" a saccade in a two-frame apparent motion display in which the two frames were separated by a saccade. We found that transformational apparent motion, in which an object is seen to change shape and even move in three dimensions during the motion trajectory, continues across saccades. Moreover, participants preferred an interpretation of motion in spatial, rather than retinal, coordinates. The strength of the motion percept depended on the temporal delay between the two motion frames and was sufficient to give rise to a motion-from-shape aftereffect, even when the motion was defined by a second-order shape cue ("phantom transformational apparent motion"). These findings suggest that motion and shape information are integrated across saccades into a single, coherent percept of a moving object.

  7. Lack of effects of astemizole on vestibular ocular reflex, motion sickness, and cognitive performance in man

    Science.gov (United States)

    Kohl, Randall L.; Homick, Jerry L.; Cintron, Nitza; Calkins, Dick S.

    1987-01-01

    Astemizole was orally administered to 20 subjects in a randomized, double-blind design to assess the efficacy of this peripherally active antihistamine as an antimotion sickness drug possessing no central side-effects. Measures of vestibular ocular reflex (VOR) were made to evaluate the agent as a selective vestibular depressant. Following one week of orally administered astemizole (30 mg daily), a Staircase Profile Test, a VOR test, and a variety of tests of cognitive performance were administered. These tests revealed no statistically significant effects of astemizole. This leads to the conclusion that, although the drug probably reaches the peripheral vestibular apparatus in man by crossing the blood-vestibular barrier, a selective peripheral antihistamine (H1) action is inadequate to control motion sickness induced through cross-coupled accelerative semicircular canal stimulation in a rotating chair.

  8. Motion perception modelling in flight simulation

    NARCIS (Netherlands)

    Groen, E.L.; Hosman, R.J.A.W.; Bos, J.E.; Dominicus, J.W.

    2004-01-01

    Motion cueing algorithms are indispensable to transform aircraft motions into simulator motions. Usually, such algorithms apply to the whole flight envelope. Since a motion base should stay within its six degrees of freedom workspace, the parameter settings necessarily involve concessions, which may

  9. Perception of complex motion in humans and pigeons (Columba livia).

    Science.gov (United States)

    Nankoo, Jean-François; Madan, Christopher R; Spetch, Marcia L; Wylie, Douglas R

    2014-06-01

    In the primate visual system, local motion signals are pooled to create a global motion percept. Like primates, many birds are highly dependent on vision for their survival, yet relatively little is known about motion perception in birds. We used random-dot stimuli to investigate pigeons' ability to detect complex motion (radial, rotation, and spiral) compared to humans. Our human participants had a significantly lower threshold for rotational and radial motion when compared to spiral motion. The data from the pigeons, however, showed that the pigeons were most sensitive to rotational motion and least sensitive to radial motion, while sensitivity for spiral motion was intermediate. We followed up the pigeon results with an investigation of the effect of display aperture shape for rotational motion and velocity gradient for radial motion. We found no effect of shape of the aperture on thresholds, but did observe that radial motion containing accelerating dots improved thresholds. However, this improvement did not reach the thresholds levels observed for rotational motion. In sum, our experiments demonstrate that the pooling mechanism in the pigeon motion system is most efficient for rotation.

  10. The human translational vestibulo-ocular reflex in response to complex motion.

    Science.gov (United States)

    Walker, Mark; Liao, Ke

    2011-09-01

    We studied the translational vestibulo-ocular reflex (tVOR) in four healthy human subjects during complex, unpredictable sum-of-sines head motion (combination of 0.73, 1.33, 1.93, and 2.93 Hz), while subjects viewed a target 15 cm away. Ideal eye velocity was calculated from recorded head motion; actual eye velocity was measured with scleral coils. The gain and phase for each frequency component was determined by least-squares optimization. Gain averaged approximately 40% and did not change with frequency; phase lag increased with frequency to a maximum of 66°. Fitting actual to ideal eye velocity predicted a tVOR latency of 48 m/s for vertical and 38 m/s for horizontal translation. These findings provide further evidence that the normal tVOR is considerably undercompensatory, even at low frequencies if the stimulus is not predictable. The similarity of this behavior to that of pursuit suggests that these two eye movements may share some aspects of neural processing.

  11. Perceptual Training Strongly Improves Visual Motion Perception in Schizophrenia

    Science.gov (United States)

    Norton, Daniel J.; McBain, Ryan K.; Ongur, Dost; Chen, Yue

    2011-01-01

    Schizophrenia patients exhibit perceptual and cognitive deficits, including in visual motion processing. Given that cognitive systems depend upon perceptual inputs, improving patients' perceptual abilities may be an effective means of cognitive intervention. In healthy people, motion perception can be enhanced through perceptual learning, but it…

  12. Perceptual Training Strongly Improves Visual Motion Perception in Schizophrenia

    Science.gov (United States)

    Norton, Daniel J.; McBain, Ryan K.; Ongur, Dost; Chen, Yue

    2011-01-01

    Schizophrenia patients exhibit perceptual and cognitive deficits, including in visual motion processing. Given that cognitive systems depend upon perceptual inputs, improving patients' perceptual abilities may be an effective means of cognitive intervention. In healthy people, motion perception can be enhanced through perceptual learning, but it…

  13. Effects of auditory information on self-motion perception during simultaneous presentation of visual shearing motion.

    Science.gov (United States)

    Tanahashi, Shigehito; Ashihara, Kaoru; Ujike, Hiroyasu

    2015-01-01

    Recent studies have found that self-motion perception induced by simultaneous presentation of visual and auditory motion is facilitated when the directions of visual and auditory motion stimuli are identical. They did not, however, examine possible contributions of auditory motion information for determining direction of self-motion perception. To examine this, a visual stimulus projected on a hemisphere screen and an auditory stimulus presented through headphones were presented separately or simultaneously, depending on experimental conditions. The participant continuously indicated the direction and strength of self-motion during the 130-s experimental trial. When the visual stimulus with a horizontal shearing rotation and the auditory stimulus with a horizontal one-directional rotation were presented simultaneously, the duration and strength of self-motion perceived in the opposite direction of the auditory rotation stimulus were significantly longer and stronger than those perceived in the same direction of the auditory rotation stimulus. However, the auditory stimulus alone could not sufficiently induce self-motion perception, and if it did, its direction was not consistent within each experimental trial. We concluded that auditory motion information can determine perceived direction of self-motion during simultaneous presentation of visual and auditory motion information, at least when visual stimuli moved in opposing directions (around the yaw-axis). We speculate that the contribution of auditory information depends on the plausibility and information balance of visual and auditory information.

  14. Meaningful auditory information enhances perception of visual biological motion.

    Science.gov (United States)

    Arrighi, Roberto; Marini, Francesco; Burr, David

    2009-04-30

    Robust perception requires efficient integration of information from our various senses. Much recent electrophysiology points to neural areas responsive to multisensory stimulation, particularly audiovisual stimulation. However, psychophysical evidence for functional integration of audiovisual motion has been ambiguous. In this study we measure perception of an audiovisual form of biological motion, tap dancing. The results show that the audio tap information interacts with visual motion information, but only when in synchrony, demonstrating a functional combination of audiovisual information in a natural task. The advantage of multimodal combination was better than the optimal maximum likelihood prediction.

  15. A substantial and unexpected enhancement of motion perception in autism.

    Science.gov (United States)

    Foss-Feig, Jennifer H; Tadin, Duje; Schauder, Kimberly B; Cascio, Carissa J

    2013-05-08

    Atypical perceptual processing in autism spectrum disorder (ASD) is well documented. In addition, growing evidence supports the hypothesis that an excitatory/inhibitory neurochemical imbalance might underlie ASD. Here we investigated putative behavioral consequences of the excitatory/inhibitory imbalance in the context of visual motion perception. As stimulus size increases, typical observers exhibit marked impairments in perceiving motion of high-contrast stimuli. This result, termed "spatial suppression," is believed to reflect inhibitory motion-processing mechanisms. Motion processing is also affected by gain control, an inhibitory mechanism that underlies saturation of neural responses at high contrast. Motivated by these behavioral correlates of inhibitory function, we investigated motion perception in human children with ASD (n = 20) and typical development (n = 26). At high contrast, both groups exhibited similar impairments in motion perception with increasing stimulus size, revealing no apparent differences in spatial suppression. However, there was a substantial enhancement of motion perception in ASD: children with ASD exhibited a consistent twofold improvement in perceiving motion. Hypothesizing that this enhancement might indicate abnormal weakening of response gain control, we repeated our measurements at low contrast, where the effects of gain control should be negligible. At low contrast, we indeed found no group differences in motion discrimination thresholds. These low-contrast results, however, revealed weaker spatial suppression in ASD, suggesting the possibility that gain control abnormalities in ASD might have masked spatial suppression differences at high contrast. Overall, we report a pattern of motion perception abnormalities in ASD that includes substantial enhancements at high contrast and is consistent with an underlying excitatory/inhibitory imbalance.

  16. Influence of Visual Motion, Suggestion, and Illusory Motion on Self-Motion Perception in the Horizontal Plane.

    Directory of Open Access Journals (Sweden)

    Steven David Rosenblatt

    Full Text Available A moving visual field can induce the feeling of self-motion or vection. Illusory motion from static repeated asymmetric patterns creates a compelling visual motion stimulus, but it is unclear if such illusory motion can induce a feeling of self-motion or alter self-motion perception. In these experiments, human subjects reported the perceived direction of self-motion for sway translation and yaw rotation at the end of a period of viewing set visual stimuli coordinated with varying inertial stimuli. This tested the hypothesis that illusory visual motion would influence self-motion perception in the horizontal plane. Trials were arranged into 5 blocks based on stimulus type: moving star field with yaw rotation, moving star field with sway translation, illusory motion with yaw, illusory motion with sway, and static arrows with sway. Static arrows were used to evaluate the effect of cognitive suggestion on self-motion perception. Each trial had a control condition; the illusory motion controls were altered versions of the experimental image, which removed the illusory motion effect. For the moving visual stimulus, controls were carried out in a dark room. With the arrow visual stimulus, controls were a gray screen. In blocks containing a visual stimulus there was an 8s viewing interval with the inertial stimulus occurring over the final 1s. This allowed measurement of the visual illusion perception using objective methods. When no visual stimulus was present, only the 1s motion stimulus was presented. Eight women and five men (mean age 37 participated. To assess for a shift in self-motion perception, the effect of each visual stimulus on the self-motion stimulus (cm/s at which subjects were equally likely to report motion in either direction was measured. Significant effects were seen for moving star fields for both translation (p = 0.001 and rotation (p0.1 for both. Thus, although a true moving visual field can induce self-motion, results of this

  17. A model of neural mechanisms in monocular transparent motion perception.

    Science.gov (United States)

    Raudies, Florian; Neumann, Heiko

    2010-01-01

    Transparent motion is perceived when multiple motions are presented in the same part of visual space that move in different directions or with different speeds. Several psychophysical as well as physiological experiments have studied the conditions under which motion transparency occurs. Few computational mechanisms have been proposed that allow to segregate multiple motions. We present a novel neural model which investigates the necessary mechanisms underlying initial motion detection, the required representations for velocity coding, and the integration and segregation of motion stimuli to account for the perception of transparent motion. The model extends a previously developed architecture for neural computations along the dorsal pathway, particularly, in cortical areas V1, MT, and MSTd. It emphasizes the role of feedforward cascade processing and feedback from higher to earlier processing stages for selective feature enhancement and tuning. Our results demonstrate that the model reproduces several key psychophysical findings in perceptual motion transparency using random dot stimuli. Moreover, the model is able to process transparent motion as well as opaque surface motion in real-world sequences of 3-d scenes. As a main thesis, we argue that the perception of transparent motion relies on the representation of multiple velocities at one spatial location; however, this feature is necessary but not sufficient to perceive transparency. It is suggested that the activations simultaneously representing multiple activities are subsequently integrated by separate mechanisms leading to the segregation of different overlapping segments.

  18. The influence of spontaneous brain oscillations on apparent motion perception.

    Science.gov (United States)

    Sanders, Lia Lira Olivier; Auksztulewicz, Ryszard; Hohlefeld, Friederike U; Busch, Niko A; Sterzer, Philipp

    2014-11-15

    A good example of inferential processes in perception is long-range apparent motion (AM), the illusory percept of visual motion that occurs when two spatially distinct stationary visual objects are presented in alternating sequence. The AM illusion is strongest at presentation frequencies around 3 Hz. At lower presentation frequencies, the percept varies from trial to trial between AM and sequential alternation, while at higher frequencies perception varies between AM and two simultaneously flickering objects. Previous studies have demonstrated that prestimulus alpha oscillations explain trial-to-trial variability in detection performance for visual stimuli presented at threshold. In the present study, we investigated whether fluctuations of prestimulus alpha oscillations can also account for variations in AM perception. Prestimulus alpha power was stronger when observers reported AM perception in subsequent trials with low presentation frequencies, while at high presentation frequencies there were no significant differences in alpha power preceding AM and veridical flicker perception. Moreover, when observers perceived AM the prestimulus functional connectivity between frontal and occipital channels was increased in the alpha band, as revealed by the imaginary part of coherency, which is insensitive to artefacts from volume conduction. Dynamic causal modelling of steady-state responses revealed that the most likely direction of this fronto-occipital connectivity was from frontal to occipital sources. These results point to a role of ongoing alpha oscillations in the inferential process that gives rise to the perception of AM and suggest that fronto-occipital interactions bias perception towards internally generated predictions.

  19. Impairments of biological motion perception in congenital prosopagnosia.

    Science.gov (United States)

    Lange, Joachim; de Lussanet, Marc; Kuhlmann, Simone; Zimmermann, Anja; Lappe, Markus; Zwitserlood, Pienie; Dobel, Christian

    2009-10-12

    Prosopagnosia is a deficit in recognizing people from their faces. Acquired prosopagnosia results after brain damage, developmental or congenital prosopagnosia (CP) is not caused by brain lesion, but has presumably been present from early childhood onwards. Since other sensory, perceptual, and cognitive abilities are largely spared, CP is considered to be a stimulus-specific deficit, limited to face processing. Given that recent behavioral and imaging studies indicate a close relationship of face and biological-motion perception in healthy adults, we hypothesized that biological motion processing should be impaired in CP. Five individuals with CP and ten matched healthy controls were tested with diverse biological-motion stimuli and tasks. Four of the CP individuals showed severe deficits in biological-motion processing, while one performed within the lower range of the controls. A discriminant analysis classified all participants correctly with a very high probability for each participant. These findings demonstrate that in CP, impaired perception of faces can be accompanied by impaired biological-motion perception. We discuss implications for dedicated and shared mechanisms involved in the perception of faces and biological motion.

  20. Impairments of biological motion perception in congenital prosopagnosia.

    Directory of Open Access Journals (Sweden)

    Joachim Lange

    Full Text Available Prosopagnosia is a deficit in recognizing people from their faces. Acquired prosopagnosia results after brain damage, developmental or congenital prosopagnosia (CP is not caused by brain lesion, but has presumably been present from early childhood onwards. Since other sensory, perceptual, and cognitive abilities are largely spared, CP is considered to be a stimulus-specific deficit, limited to face processing. Given that recent behavioral and imaging studies indicate a close relationship of face and biological-motion perception in healthy adults, we hypothesized that biological motion processing should be impaired in CP. Five individuals with CP and ten matched healthy controls were tested with diverse biological-motion stimuli and tasks. Four of the CP individuals showed severe deficits in biological-motion processing, while one performed within the lower range of the controls. A discriminant analysis classified all participants correctly with a very high probability for each participant. These findings demonstrate that in CP, impaired perception of faces can be accompanied by impaired biological-motion perception. We discuss implications for dedicated and shared mechanisms involved in the perception of faces and biological motion.

  1. "外星行星"和"反映运动"%Exoplanet and Reflex Motion

    Institute of Scientific and Technical Information of China (English)

    李竞

    2004-01-01

    @@ 大多数天文学家都坚信,在恒星世界中,行星系的存在是宇宙的普遍规律.然而用天文方法发现和检测太阳系外行星(extrasolar planet),也就是"外星行星"(exoplanet)却是一项艰巨的观测难题.天文学家都知道行星在它所从属的恒星引力作用下,围绕恒星运行.同时还知道,行星质量比恒星小得多,引力也比恒星弱得多,但对恒星同样也有影响.在行星引力作用下,恒星随着行星的公转而作周期摆动.天文学家将因行星的存在而叠加在恒星空间运动上的附加值,称为"反映运动"(reflex motion).

  2. A multilayer neural network model for perception of rotational motion

    Institute of Scientific and Technical Information of China (English)

    郭爱克; 孙海坚; 杨先一

    1997-01-01

    A multilayer neural nerwork model for the perception of rotational motion has been developed usingReichardt’s motion detector array of correlation type, Kohonen’s self-organized feature map and Schuster-Wagner’s oscillating neural network. It is shown that the unsupervised learning could make the neurons on the second layer of the network tend to be self-organized in a form resembling columnar organization of selective directions in area MT of the primate’s visual cortex. The output layer can interpret rotation information and give the directions and velocities of rotational motion. The computer simulation results are in agreement with some psychophysical observations of rotation-al perception. It is demonstrated that the temporal correlation between the oscillating neurons would be powerful for solving the "binding problem" of shear components of rotational motion.

  3. A Pursuit Theory Account for the Perception of Common Motion in Motion Parallax.

    Science.gov (United States)

    Ratzlaff, Michael; Nawrot, Mark

    2016-09-01

    The visual system uses an extraretinal pursuit eye movement signal to disambiguate the perception of depth from motion parallax. Visual motion in the same direction as the pursuit is perceived nearer in depth while visual motion in the opposite direction as pursuit is perceived farther in depth. This explanation of depth sign applies to either an allocentric frame of reference centered on the fixation point or an egocentric frame of reference centered on the observer. A related problem is that of depth order when two stimuli have a common direction of motion. The first psychophysical study determined whether perception of egocentric depth order is adequately explained by a model employing an allocentric framework, especially when the motion parallax stimuli have common rather than divergent motion. A second study determined whether a reversal in perceived depth order, produced by a reduction in pursuit velocity, is also explained by this model employing this allocentric framework. The results show than an allocentric model can explain both the egocentric perception of depth order with common motion and the perceptual depth order reversal created by a reduction in pursuit velocity. We conclude that an egocentric model is not the only explanation for perceived depth order in these common motion conditions.

  4. Common mechanisms in apparent motion perception and visual pattern matching.

    Science.gov (United States)

    Larsen, Axel; Bundesen, Claus

    2009-12-01

    Common mechanisms in apparent motion perception and visual pattern matching. Scandinavian Journal of Psychology, 50, 526-534.There are close functional similarities between apparent motion perception and visual pattern matching. In particular, striking functional similarities have been demonstrated between perception of rigid objects in apparent motion and purely mental transformations of visual size and orientation used in comparisons of objects with respect to shape but regardless of size and orientation. In both cases, psychophysical data suggest that differences in visual size are resolved as differences in depth, such that transformation of size is done by translation in depth. Furthermore, the process of perceived or imagined translation appears to be stepwise additive such that a translation over a long distance consists of a sequence of smaller translations, the durations of these steps being additive. Both perceived and imagined rotation also appear to be stepwise additive, and combined transformations of size and orientation appear to be done by alternation of small steps of pure translation and small steps of pure rotation. The functional similarities suggest that common mechanisms underlie perception of apparent motion and purely mental transformations. In line with this suggestion, functional brain imaging has isolated neural structures in motion area MT used in mental transformation of size.

  5. Modification of Eye Movements and Motion Perception during Off-Vertical Axis Rotation

    Science.gov (United States)

    Wood, S. J.; Reschke, M. F.; Denise, P.; CLement, G.

    2006-01-01

    Constant velocity Off-Vertical Axis Rotation (OVAR) imposes a continuously varying orientation of the head and body relative to gravity. The ensuing ocular reflexes include modulation of both torsional and horizontal eye movements as a function of the varying linear acceleration along the lateral plane, and modulation of vertical and vergence eye movements as a function of the varying linear acceleration along the sagittal plane. Previous studies have demonstrated that tilt and translation otolith-ocular responses, as well as motion perception, vary as a function of stimulus frequency during OVAR. The purpose of this study is to examine normative OVAR responses in healthy human subjects, and examine adaptive changes in astronauts following short duration space flight at low (0.125 Hz) and high (0.5 Hz) frequencies. Data was obtained on 24 normative subjects (14 M, 10 F) and 14 (13 M, 1F) astronaut subjects. To date, astronauts have participated in 3 preflight sessions (n=14) and on R+0/1 (n=7), R+2 (n= 13) and R+4 (n= 13) days after landing. Subjects were rotated in darkness about their longitudinal axis 20 deg off-vertical at constant rates of 45 and 180 deg/s, corresponding to 0.125 and 0.5 Hz. Binocular responses were obtained with video-oculography. Perceived motion was evaluated using verbal reports and a two-axis joystick (pitch and roll tilt) mounted on top of a two-axis linear stage (anterior-posterior and medial-lateral translation). Eye responses were obtained in ten of the normative subjects with the head and trunk aligned, and then with the head turned relative to the trunk 40 deg to the right or left of center. Sinusoidal curve fits were used to derive amplitude, phase and bias of the responses over several cycles at each stimulus frequency. Eye responses during 0.125 Hz OVAR were dominated by modulation of torsional and vertical eye position, compensatory for tilt relative to gravity. While there is a bias horizontal slow phase velocity (SPV), the

  6. Motion perception thresholds in flight simulation

    NARCIS (Netherlands)

    Groen, E.L.; Wentink, M.; Valente Pais, A.R.; Mulder, M.; Paassen, M.M. van

    2006-01-01

    Pilot perception models include detailed descriptions of the sensory dynamics involved in human spatial orientation. For example, the TNO Spatial Orientation model contains transfer functions of the visual and vestibular system (semicircular canals and otoliths). In our previous attempts to apply th

  7. Motion perception thresholds in flight simulation

    NARCIS (Netherlands)

    Groen, E.L.; Wentink, M.; Valente Pais, A.R.; Mulder, M.; Paassen, M.M. van

    2006-01-01

    Pilot perception models include detailed descriptions of the sensory dynamics involved in human spatial orientation. For example, the TNO Spatial Orientation model contains transfer functions of the visual and vestibular system (semicircular canals and otoliths). In our previous attempts to apply

  8. Motion perception thresholds in flight simulation

    NARCIS (Netherlands)

    Groen, E.L.; Wentink, M.; Valente Pais, A.R.; Mulder, M.; Paassen, M.M. van

    2006-01-01

    Pilot perception models include detailed descriptions of the sensory dynamics involved in human spatial orientation. For example, the TNO Spatial Orientation model contains transfer functions of the visual and vestibular system (semicircular canals and otoliths). In our previous attempts to apply th

  9. Influence of Visual Motion on Tactile Motion Perception

    Science.gov (United States)

    Bensmaïa, S. J.; Killebrew, J. H.; Craig, J. C.

    2007-01-01

    Subjects were presented with pairs of tactile drifting sinusoids and made speed discrimination judgments. On some trials, a visual drifting sinusoid, which subjects were instructed to ignore, was presented simultaneously with one of the two tactile stimuli. When the visual and tactile gratings drifted in the same direction (i.e., from left to right), the visual distractors were found to increase the perceived speed of the tactile gratings. The effect of the visual distractors was proportional to their temporal frequency but not to their perceived speed. When the visual and tactile gratings drifted in opposite directions, the distracting effect of the visual distractors was either substantially reduced or, in some cases, reversed (i.e., the distractors slowed the perceived speed of the tactile gratings). This result suggests that the observed visual-tactile interaction is dependent on motion and not simply on the oscillations inherent in drifting sinusoids. Finally, we find that disrupting the temporal synchrony between the visual and tactile stimuli eliminates the distracting effect of the visual stimulus. We interpret this latter finding as evidence that the observed visual-tactile interaction operates at the sensory level and does not simply reflect a response bias. PMID:16723415

  10. Relation between perception of vertical axis rotation and vestibulo-ocular reflex symmetry

    Science.gov (United States)

    Peterka, Robert J.; Benolken, Martha S.

    1992-01-01

    Subjects seated in a vertical axis rotation chair controlled their rotational velocity by adjusting a potentiometer. Their goal was to null out pseudorandom rotational perturbations in order to remain perceptually stationary. Most subjects showed a slow linear drift of velocity (a constant acceleration) to one side when they were deprived of an earth-fixed visual reference. The amplitude and direction of this drift can be considered a measure of a static bias in the subject's perception of rotation. The presence of a perceptual bias is consistent with a small, constant imbalance of vestibular function which could be of either central or peripheral origin. Deviations from perfect vestibulo-ocular reflex (VOR) symmetry are also assumed to be related to imbalances in either peripheral or central vestibular function. Researchers looked for correlations between perceptual bias and various measures of vestibular reflex symmetry that might suggest a common source for both reflective and perceptual imbalances. No correlations were found. Measurement errors could not account for these results since repeated tests on the same subjects of both perceptual bias and VOR symmetry were well correlated.

  11. Multisensory perception of spatial orientation and self-motion

    NARCIS (Netherlands)

    de Winkel, K.N.

    2013-01-01

    The aim of this project was to improve our insight in how the brain combines information from different sensory systems (e.g. vestibular and visual system) into an integrated percept of self-motion and spatial orientation. Based on evidence from other research in different areas, such as hand-eye

  12. Self-motion perception compresses time experienced in return travel.

    Science.gov (United States)

    Seno, Takeharu; Ito, Hiroyuki; Shoji, Sunaga

    2011-01-01

    It is often anecdotally reported that time experienced in return travel (back to the start point) seems shorter than time spent in outward travel (travel to a new destination). Here, we report the first experimental results showing that return travel time is experienced as shorter than the actual time. This discrepancy is induced by the existence of self-motion perception.

  13. Neurophysiological and Behavioural Correlates of Coherent Motion Perception in Dyslexia

    Science.gov (United States)

    Taroyan, Naira A.; Nicolson, Roderick I.; Buckley, David

    2011-01-01

    Coherent motion perception was tested in nine adolescents with dyslexia and 10 control participants matched for age and IQ using low contrast stimuli with three levels of coherence (10%, 25% and 40%). Event-related potentials (ERPs) and behavioural performance data were obtained. No significant between-group differences were found in performance…

  14. Apparent motion perception in patients with paranoid schizophrenia.

    Science.gov (United States)

    Sanders, Lia Lira Olivier; de Millas, Walter; Heinz, Andreas; Kathmann, Norbert; Sterzer, Philipp

    2013-04-01

    Impaired perceptual inference has been suggested to be at the core of positive symptoms in schizophrenia. Apparent motion (AM) is a visual illusion in which perceptual inference gives rise to the experience of a single object moving back and forth when two spatially separated objects are flashed in alternation. Here, we investigated the strength of AM perception in patients with paranoid schizophrenia. Patients were less susceptible to the illusion as indicated by a lower probability of motion perception at the individual's optimal presentation frequency for AM. In addition, the probability of AM perception was inversely related to delusional conviction in the patient group. These results suggest that schizophrenia may be associated with a reduced susceptibility to visual phenomena that commonly rely on perceptual inference.

  15. Comparing biological motion perception in two distinct human societies.

    Directory of Open Access Journals (Sweden)

    Pierre Pica

    Full Text Available Cross cultural studies have played a pivotal role in elucidating the extent to which behavioral and mental characteristics depend on specific environmental influences. Surprisingly, little field research has been carried out on a fundamentally important perceptual ability, namely the perception of biological motion. In this report, we present details of studies carried out with the help of volunteers from the Mundurucu indigene, a group of people native to Amazonian territories in Brazil. We employed standard biological motion perception tasks inspired by over 30 years of laboratory research, in which observers attempt to decipher the walking direction of point-light (PL humans and animals. Do our effortless skills at perceiving biological activity from PL animations, as revealed in laboratory settings, generalize to people who have never before seen representational depictions of human and animal activity? The results of our studies provide a clear answer to this important, previously unanswered question. Mundurucu observers readily perceived the coherent, global shape depicted in PL walkers, and experienced the classic inversion effects that are typically found when such stimuli are turned upside down. In addition, their performance was in accord with important recent findings in the literature, in the abundant ease with which they extracted direction information from local motion invariants alone. We conclude that the effortless, veridical perception of PL biological motion is a spontaneous and universal perceptual ability, occurring both inside and outside traditional laboratory environments.

  16. Motion parallax contribution to perception of self-motion and depth.

    Science.gov (United States)

    Hanes, Douglas A; Keller, Julia; McCollum, Gin

    2008-04-01

    The object of this study is to mathematically specify important characteristics of visual flow during translation of the eye for the perception of depth and self-motion. We address various strategies by which the central nervous system may estimate self-motion and depth from motion parallax, using equations for the visual velocity field generated by translation of the eye through space. Our results focus on information provided by the movement and deformation of three-dimensional objects and on local flow behavior around a fixated point. All of these issues are addressed mathematically in terms of definite equations for the optic flow. This formal characterization of the visual information presented to the observer is then considered in parallel with other sensory cues to self-motion in order to see how these contribute to the effective use of visual motion parallax, and how parallactic flow can, conversely, contribute to the sense of self-motion. This article will focus on a central case, for understanding of motion parallax in spacious real-world environments, of monocular visual cues observable during pure horizontal translation of the eye through a stationary environment. We suggest that the global optokinetic stimulus associated with visual motion parallax must converge in significant fashion with vestibular and proprioceptive pathways that carry signals related to self-motion. Suggestions of experiments to test some of the predictions of this study are made.

  17. Neural correlates of induced motion perception in the human brain.

    Science.gov (United States)

    Takemura, Hiromasa; Ashida, Hiroshi; Amano, Kaoru; Kitaoka, Akiyoshi; Murakami, Ikuya

    2012-10-10

    A physically stationary stimulus surrounded by a moving stimulus appears to move in the opposite direction. There are similarities between the characteristics of this phenomenon of induced motion and surround suppression of directionally selective neurons in the brain. Here, functional magnetic resonance imaging was used to investigate the link between the subjective perception of induced motion and cortical activity. The visual stimuli consisted of a central drifting sinusoid surrounded by a moving random-dot pattern. The change in cortical activity in response to changes in speed and direction of the central stimulus was measured. The human cortical area hMT+ showed the greatest activation when the central stimulus moved at a fast speed in the direction opposite to that of the surround. More importantly, the activity in this area was the lowest when the central stimulus moved in the same direction as the surround and at a speed such that the central stimulus appeared to be stationary. The results indicate that the activity in hMT+ is related to perceived speed modulated by induced motion rather than to physical speed or a kinetic boundary. Early visual areas (V1, V2, V3, and V3A) showed a similar pattern; however, the relationship to perceived speed was not as clear as that in hMT+. These results suggest that hMT+ may be a neural correlate of induced motion perception and play an important role in contrasting motion signals in relation to their surrounding context and adaptively modulating our motion perception depending on the spatial context.

  18. Is vestibular self-motion perception controlled by the velocity storage? Insights from patients with chronic degeneration of the vestibulo-cerebellum.

    Directory of Open Access Journals (Sweden)

    Giovanni Bertolini

    Full Text Available BACKGROUND: The rotational vestibulo-ocular reflex (rVOR generates compensatory eye movements in response to rotational head accelerations. The velocity-storage mechanism (VSM, which is controlled by the vestibulo-cerebellar nodulus and uvula, determines the rVOR time constant. In healthy subjects, it has been suggested that self-motion perception in response to earth-vertical axis rotations depends on the VSM in a similar way as reflexive eye movements. We aimed at further investigating this hypothesis and speculated that if the rVOR and rotational self-motion perception share a common VSM, alteration in the latter, such as those occurring after a loss of the regulatory control by vestibulo-cerebellar structures, would result in similar reflexive and perceptual response changes. We therefore set out to explore both responses in patients with vestibulo-cerebellar degeneration. METHODOLOGY/PRINCIPAL FINDINGS: Reflexive eye movements and perceived rotational velocity were simultaneously recorded in 14 patients with chronic vestibulo-cerebellar degeneration (28-81 yrs and 12 age-matched healthy subjects (30-72 yrs after the sudden deceleration (90°/s2 from constant-velocity (90°/s rotations about the earth-vertical yaw and pitch axes. rVOR and perceived rotational velocity data were analyzed using a two-exponential model with a direct pathway, representing semicircular canal activity, and an indirect pathway, implementing the VSM. We found that VSM time constants of rVOR and perceived rotational velocity co-varied in cerebellar patients and in healthy controls (Pearson correlation coefficient for yaw 0.95; for pitch 0.93, p0.8. CONCLUSIONS/SIGNIFICANCE: Our results confirm that self-motion perception in response to rotational velocity-steps may be controlled by the same velocity storage network that controls reflexive eye movements and that no additional, e.g. cortical, mechanisms are required to explain perceptual dynamics.

  19. An asymmetry of translational biological motion perception in schizophrenia

    Directory of Open Access Journals (Sweden)

    Caitlin eHastings

    2013-07-01

    Full Text Available Background Biological motion perception is served by a network of regions in the occipital, posterior temporal and parietal lobe, overlapping areas of reduced cortical volume in schizophrenia. The atrophy in these regions is assumed to account for deficits in biological motion perception described in schizophrenia but it is unknown whether the asymmetry of atrophy described in previous studies has a perceptual correlate. Here we look for possible differences in sensitivity to leftwards and rightwards translation of point-light biological motion in data collected for a previous study and explore its underlying neurobiology using functional imaging. Methods n=64 patients with schizophrenia and n=64 controls performed a task requiring the detection of leftward or rightward biological motion using a standard psychophysical staircase procedure. 6 control subjects took part in the functional imaging experiment. Results We found a deficit of leftward but not rightward biological motion (leftward biological motion % accuracy patients = 57.9%±14.3; controls = 63.6%±11.3 p=0.01; rightward biological motion patients = 62.7%±12.4; controls = 64.1%±11.7; p>0.05. The deficit reflected differences in distribution of leftward and rightward accuracy bias in the two populations. Directional bias correlated with functional outcome as measured by the Role Functioning Scale in the patient group when co-varying for negative symptoms (r=-0.272, p=0.016. Cortical regions with preferential activation for leftwards or rightwards translation were identified in both hemispheres suggesting the psychophysical findings could not be accounted for by selective atrophy or functional change in one hemisphere alone. Conclusions The findings point to translational direction as a novel functional probe to help understand the underlying neural mechanisms of wider cognitive dysfunction in schizophrenia.

  20. Dynamic perspective cues enhance depth perception from motion parallax.

    Science.gov (United States)

    Buckthought, Athena; Yoonessi, Ahmad; Baker, Curtis L

    2017-01-01

    Motion parallax, the perception of depth resulting from an observer's self-movement, has almost always been studied with random dot textures in simplified orthographic rendering. Here we examine depth from motion parallax in more naturalistic conditions using textures with an overall 1/f spectrum and dynamic perspective rendering. We compared depth perception for orthographic and perspective rendering, using textures composed of two types of elements: random dots and Gabor micropatterns. Relative texture motion (shearing) with square wave corrugation patterns was synchronized to horizontal head movement. Four observers performed a two-alternative forced choice depth ordering task with monocular viewing, in which they reported which part of the texture appeared in front of the other. For both textures, depth perception was better with dynamic perspective than with orthographic rendering, particularly at larger depths. Depth ordering performance with naturalistic 1/f textures was slightly lower than with the random dots; however, with depth-related size scaling of the micropatterns, performance was comparable to that with random dots. We also examined the effects of removing each of the three cues that distinguish dynamic perspective from orthographic rendering: (a) small vertical displacements, (b) lateral gradients of speed across the corrugations, and (c) speed differences in rendered near versus far surfaces. Removal of any of the three cues impaired performance. In conclusion, depth ordering performance is enhanced by all of the dynamic perspective cues but not by using more naturalistic 1/f textures.

  1. Torsional vestibulo-ocular reflex measurements for identifying otolith asymmetries possibly related to space motion sickness susceptibility

    Science.gov (United States)

    Peterka, Robert J.

    Recent studies by Diamond and Markham 1,2 have identified significant correlations between space motion sickness susceptibility and measures of disconjugate torsional eye movements recorded during parabolic flights. These results support an earlier proposal by von Baumgarten and Thümler 3 which hypothesized that an asymmetry of otolith function between the two ears is the cause of space motion sickness. It may be possible to devise experiments that can be performed in the 1 g environment on earth that could identify and quantify the presence of asymmetric otolith function. This paper summarizes the known physiological and anatomical properties of the otolith organs and the properties of the torsional vestibulo-ocular reflex which are relevant to the design of a stimulus to identify otolith asymmetries. A specific stimulus which takes advantage of these properties is proposed.

  2. Perceptual atoms: proximal motion vector-structures and the perception of object motion in depth

    Directory of Open Access Journals (Sweden)

    Hershenson Maurice

    2003-01-01

    Full Text Available A framework is proposed for analyzing the perception of motion in depth produced by simple proximal motion patterns of two to four points. The framework includes input structure, perceptual system constraints, and a depth scaling mechanism. The input is relational stimulation described by two proximal dimensions, orientation and separation, that can change or remain constant over the course of a motion pattern. Combinations of change or no-change in these dimensions yield four basic patterns of proximal stimulation: parallel, circular, perspective, and parallax. These primary patterns initiate automatic processing mechanisms - a unity constraint that treats pairs of points as connected and a rigidity constraint that treats the connection as rigid. When the constraints are activated by perspective or parallax patterns, the rigid connection between the points also appears to move in depth. A scaling mechanism governs the degree to which the objects move in depth in order to maintain the perceived rigidity. Although this framework is sufficient to explain perceptions produced by three- and four-point motion patterns in most cases, some patterns require additional configurational factors to supplement the framework. Nevertheless, perceptual qualities such as shrinking, stretching, bending, and folding emerge from the application of the same processing constraints and depth scaling factors as those that produce the perception of rigid objects moving in depth.

  3. Perception of biological motion from size-invariant body representations

    Directory of Open Access Journals (Sweden)

    Markus eLappe

    2015-03-01

    Full Text Available The visual recognition of action is one of the socially most important and computationally demanding capacities of the human visual system. It combines visual shape recognition with complex non-rigid motion perception. Action presented as a point-light animation is a striking visual experience for anyone who sees it for the first time. Information about the shape and posture of the human body is sparse in point-light animations, but it is essential for action recognition. In the posturo-temporal filter model of biological motion perception posture information is picked up by visual neurons tuned to the form of the human body before body motion is calculated. We tested whether point-light stimuli are processed through posture recognition of the human body form by using a typical feature of form recognition, namely size invariance. We constructed a point-light stimulus that can only be perceived through a size-invariant mechanism. This stimulus changes rapidly in size from one image to the next. It thus disrupts continuity of early visuo-spatial properties but maintains continuity of the body posture representation. Despite this massive manipulation at the visuo-spatial level, size-changing point-light figures are spontaneously recognized by naive observers, and support discrimination of human body motion.

  4. Space and motion perception and discomfort in air travel.

    Science.gov (United States)

    Ramos, Renato T; de Mattos, Danielle A; Rebouças, J Thales S; Ranvaud, Ronald D

    2012-12-01

    The perception of comfort during air trips is determined by several factors. External factors like cabin design and environmental parameters (temperature, humidity, air pressure, noise, and vibration) interact with individual characteristics (anxiety traits, fear of flying, and personality) from arrival at the airport to landing at the destination. In this study, we investigated the influence of space and motion discomfort (SMD), fear of heights, and anxiety on comfort perception during all phases of air travel. We evaluated 51 frequent air travelers through a modified version of the Flight Anxiety Situations Questionnaire (FAS), in which new items were added and where the subjects were asked to report their level of discomfort or anxiety (not fear) for each phase of air travel (Chronbach's alpha = 0.974). Correlations were investigated among these scales: State-Trait Anxiety Inventory (STAI), Cohen's Acrophobia Questionnaire, and the Situational Characteristics Questionnaire (SitQ, designed to estimate SMD levels). Scores of SitQ correlated with discomfort in situations involving space and movement perception (Pearson's rho = 0.311), while discomfort was associated with cognitive mechanisms related to scores in the anxiety scales (Pearson's rho = 0.375). Anxiety traits were important determinants of comfort perception before and after flight, while the influence of SMD was more significant during the time spent in the aircraft cabin. SMD seems to be an important modulator of comfort perception in air travel. Its influence on physical well being and probably on cognitive performance, with possible effects on flight safety, deserves further investigation.

  5. Reflex responses to combined hip and knee motion in human chronic spinal cord injury

    Directory of Open Access Journals (Sweden)

    Ming Wu, PhD

    2010-04-01

    Full Text Available The relative contributions of hip and knee proprioceptors to the origination of extensor spasms were examined in 11 subjects with chronic spinal cord injury (SCI. Ramp and hold extension and combined hip and knee oscillation movements were imposed to the right leg while the ankle was held in a static position by a custom-designed robot. Isometric joint torques of the hip, knee, and ankle and surface electromyograms (EMGs from seven leg muscles were recorded following controlled hip and knee extension. A stereotypical torque response consisting of hip flexion, knee extension, and ankle plantar flexion was observed following hip and knee perturbations. Further, the hip or knee joint posture modulated the spastic reflexes triggered by the extension movement of the other joint, with larger responses observed with the hip and knee extended. In addition, combined hip and knee oscillation movements were imposed to one leg with four different phasing conditions. The phasing between the hip and knee modulated the reflex activity triggered by hip and knee oscillations. The EMG patterns of the spastic reflexes were generally consistent with muscle timing during locomotion in human SCI. This knowledge may help identify rehabilitation strategies that produce functional movements in human SCI.

  6. Repetitive transcranial magnetic stimulation of human MT+ reduces apparent motion perception.

    Science.gov (United States)

    Matsuyoshi, Daisuke; Hirose, Nobuyuki; Mima, Tatsuya; Fukuyama, Hidenao; Osaka, Naoyuki

    2007-12-18

    We investigated the effects of repetitive transcranial magnetic stimulation (rTMS) over the human cerebral cortex on apparent motion perception. Previous studies have shown that human extrastriate visual area MT+ (V5) processes not only real but also apparent motion. However, the functional relevance of MT+ on long-range apparent motion perception remains unclear. Here, we show direct evidence for the involvement of MT+ in apparent motion perception using rTMS, which is known to temporarily inhibit a localized region in the cerebral cortex. The results showed that apparent motion perception decreased after applying rTMS over MT+, but not after applying rTMS over the control region (inferior temporal gyrus). The decrease in performance caused by applying rTMS to MT+ suggests that MT+ is a causally responsible region for apparent motion perception, and thus, further supports the idea that MT+ plays a major role in the perception of motion.

  7. Motion Perception of Short-Wavelength Sensitive Cones in Glaucoma Using Random Dots Moving

    Institute of Scientific and Technical Information of China (English)

    Baowen Gu; De-Zheng Wu; Jongji Liang; Minzhong Yu

    2001-01-01

    Purpose: To determine whether motion perception of short-wavelength sensitive(SWS)cones is capable of predicting primary open angle glaucoma (POAG) optic neuropathy.Methods: Motion perceptions of SWS cones were isolated by Blue random dot stimulusdisplayed on the Yellow background, then the detecting displacement threshold of motionperception from SWS cone in POAG was measured, and compared with the age-matchednormal group.Results: The detecting displacement thresholds of motion perception from SWS cones in8 sites of 15 degrees were all elevated in POAG compared with the normal group.Conclusion: These findings suggest that motion perception of SWS cones may revealpreclinical visual nerve damage in early POAG.

  8. Paradoxical perception of object identity in visual motion.

    Science.gov (United States)

    Zharikova, Aleksandra; Gepshtein, Sergei; van Leeuwen, Cees

    2017-07-01

    In the course of perceptual organization, incomplete optical stimulation can evoke the experience of complete objects with distinct perceptual identities. According to a well-known principle of perceptual organization, stimulus parts separated by shorter spatial distances are more likely to appear as parts of the same perceptual identity. Whereas this principle of proximity has been confirmed in many studies of perceptual grouping in static displays, we show that it does not generalize to perception of object identity in dynamic displays, where the parts are separated by spatial and temporal distances. We use ambiguous displays which contain multiple moving parts and which can be perceived two ways: as two large objects that gradually change their size or as multiple smaller objects that rotate independent of one another. Grouping over long and short distances corresponds to the perception of the respectively large and small objects. We find that grouping over long distances is often preferred to grouping over short distances, against predictions of the proximity principle. Even though these effects are observed at high luminance contrast, we show that they are consistent with results obtained at the threshold of luminance contrast, in agreement with predictions of a theory of efficient motion measurement. This is evidence that the perception of object identity can be explained by a computational principle of neural economy rather than by the empirical principle of proximity. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Differential brain activity states during the perception and nonperception of illusory motion as revealed by magnetoencephalography.

    Science.gov (United States)

    Crowe, David A; Leuthold, Arthur C; Georgopoulos, Apostolos P

    2010-12-28

    We studied visual perception using an annular random-dot motion stimulus called the racetrack. We recorded neural activity using magnetoencephalography while subjects viewed variants of this stimulus that contained no inherent motion or various degrees of embedded motion. Subjects reported seeing rotary motion during viewing of all stimuli. We found that, in the absence of any motion signals, patterns of brain activity differed between states of motion perception and nonperception. Furthermore, when subjects perceived motion, activity states within the brain did not differ across stimuli of different amounts of embedded motion. In contrast, we found that during periods of nonperception brain-activity states varied with the amount of motion signal embedded in the stimulus. Taken together, these results suggest that during perception the brain may lock into a stable state in which lower-level signals are suppressed.

  10. Contrasting accounts of direction and shape perception in short-range motion: Counterchange compared with motion energy detection.

    Science.gov (United States)

    Norman, Joseph; Hock, Howard; Schöner, Gregor

    2014-07-01

    It has long been thought (e.g., Cavanagh & Mather, 1989) that first-order motion-energy extraction via space-time comparator-type models (e.g., the elaborated Reichardt detector) is sufficient to account for human performance in the short-range motion paradigm (Braddick, 1974), including the perception of reverse-phi motion when the luminance polarity of the visual elements is inverted during successive frames. Human observers' ability to discriminate motion direction and use coherent motion information to segregate a region of a random cinematogram and determine its shape was tested; they performed better in the same-, as compared with the inverted-, polarity condition. Computational analyses of short-range motion perception based on the elaborated Reichardt motion energy detector (van Santen & Sperling, 1985) predict, incorrectly, that symmetrical results will be obtained for the same- and inverted-polarity conditions. In contrast, the counterchange detector (Hock, Schöner, & Gilroy, 2009) predicts an asymmetry quite similar to that of human observers in both motion direction and shape discrimination. The further advantage of counterchange, as compared with motion energy, detection for the perception of spatial shape- and depth-from-motion is discussed.

  11. Synesthesia for color is linked to improved color perception but reduced motion perception.

    Science.gov (United States)

    Banissy, Michael J; Tester, Victoria; Muggleton, Neil G; Janik, Agnieszka B; Davenport, Aimee; Franklin, Anna; Walsh, Vincent; Ward, Jamie

    2013-12-01

    Synesthesia is a rare condition in which one property of a stimulus (e.g., shape) triggers a secondary percept (e.g., color) not typically associated with the first. Work on synesthesia has predominantly focused on confirming the authenticity of synesthetic experience, but much less research has been conducted to examine the extent to which synesthesia is linked to broader perceptual differences. In the research reported here, we examined whether synesthesia is associated with differences in color and motion processing by comparing these abilities in synesthetes who experience color as their evoked sensation with nonsynesthetic participants. We show that synesthesia for color is linked to facilitated color sensitivity but decreased motion sensitivity. These findings are discussed in relation to the neurocognitive mechanisms of synesthesia and interactions between color and motion processing in typical adults.

  12. Computational model for perception of objects and motions

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Perception of objects and motions in the visual scene is one of the basic problems in the visual system. There exist ’What’ and ’Where’ pathways in the superior visual cortex, starting from the simple cells in the primary visual cortex. The former is able to perceive objects such as forms, color, and texture, and the latter perceives ’where’, for example, velocity and direction of spatial movement of objects. This paper explores brain-like computational architectures of visual information processing. We propose a visual perceptual model and computational mechanism for training the perceptual model. The compu- tational model is a three-layer network. The first layer is the input layer which is used to receive the stimuli from natural environments. The second layer is designed for representing the internal neural information. The connections between the first layer and the second layer, called the receptive fields of neurons, are self-adaptively learned based on principle of sparse neural representation. To this end, we introduce Kullback-Leibler divergence as the measure of independence between neural responses and derive the learning algorithm based on minimizing the cost function. The proposed algorithm is applied to train the basis functions, namely receptive fields, which are localized, oriented, and bandpassed. The resultant receptive fields of neurons in the second layer have the characteristics resembling that of simple cells in the primary visual cortex. Based on these basis functions, we further construct the third layer for perception of what and where in the superior visual cortex. The proposed model is able to perceive objects and their motions with a high accuracy and strong robustness against additive noise. Computer simulation results in the final section show the feasibility of the proposed perceptual model and high efficiency of the learning algorithm.

  13. Computational model for perception of objects and motions

    Institute of Scientific and Technical Information of China (English)

    YANG WenLu; ZHANG LiQing; MA LiBo

    2008-01-01

    Perception of objects and motions inthe visual scene is one of the basic problems in the visual system. There exist 'What' and 'Where' pathways in the superior visual cortex, starting from the simple cells in the primary visual cortex. The former is able to perceive objects such as forms, color, and texture, and the latter perceives 'where', for example, velocity and direction of spatial movement of objects. This paper explores brain-like computational architectures of visual information processing. We propose a visual perceptual model and computational mechanism for training the perceptual model. The compu-tational model is a three-layer network. The first layer is the input layer which is used to receive the stimuli from natural environments. The second layer is designed for representing the internal neural information. The connections between the first layer and the second layer, called the receptive fields of neurons, are self-adaptively learned based on principle of sparse neural representation, To this end, we introduce Kullback-Leibler divergence as the measure of independence between neural responses and derive the learning algorithm based on minimizing the cost function. The proposed algorithm is applied to train the basis functions, namely receptive fields, which are localized, oriented, and bandpassed. The resultant receptive fields of neurons in the second layer have the characteristics resembling that of simple cells in the primary visual cortex. Based on these basis functions, we further construct the third layer for perception of what and where in the superior visual cortex. The proposed model is able to perceive objects and their motions with a high accuracy and strong robustness against additive noise. Computer simulation results in the final section show the feasibility of the proposed perceptual model and high efficiency of the learning algorithm.

  14. Spatial perception of motion-tracked binaural sound

    Science.gov (United States)

    Melick, Joshua B.; Algazi, V. Ralph; Duda, Richard O.

    2005-04-01

    Motion-tracked binaural sound reproduction extends conventional headphone-based binaural techniques by providing the dynamic cues to sound localization produced by voluntary head motion [V. R. Algazi, R. O. Duda, and D. M. Thompson, J. Aud. Eng. Soc. 52, 1142-1156 (2004)]. It does this by using several microphones to sample the acoustic field around a dummy head, interpolating between the microphone signals in accordance with the dynamically measured orientation of the listener's head. Although the provision of dynamic cues reduces the sensitivity of the method to characteristics of the individual listener, differences between the scattered field produced by the dummy head and the scattered field that would be produced by a particular listener distorts the spatial perception. A common observation is that sound sources appear to rise in elevation when the listener turns to face them. We investigate this effect by comparing the perceived rise in elevation under three different conditions: recordings in which recordings are made using (a) the listener's own head, (b) a KEMAR mannequin, and (c) a cylindrical head with no torso. Quantitative results are presented showing the degree to which perceptual distortions are least for (a) and greatest for (c). [Work supported by NSF.

  15. The interaction of luminance, velocity, and shape information in the perception of motion transparency, coherence, and non-rigid motion.

    Science.gov (United States)

    Jasinschi, R; Rosenfeld, A; Araújo, H J

    1993-01-01

    The perception of luminance transparency for superimposed patterns depends on how luminance, figural, and topological conditions are simultaneously satisfied. Motion transparency or coherence for two superimposed patterns, which correspond to the perception of both patterns moving across one another or to the perception of compound motion of the regions of pattern intersection, depends on the relation between the local velocity, luminance, and shape information. This study analyzes how luminance, shape, and local velocity interact in the perception of motion transparency and coherence. Psychophysical experiments done with sinusoidally modulated bar patterns are presented which show that the perception of motion transparency or coherence can be described as the result of the interaction of two integration modules: the velocity-luminance and the velocity-shape processes. The velocity-luminance process describes the integration of the local velocity with luminance information. When the luminance transparency rules are satisfied this process always generates the perception of motion transparency independently of the shape or contour information. On the other hand, when the luminance transparency rules are violated one can either perceive motion coherence or non-rigid motion; one perceives motion coherence when the patterns have small or zero amplitude, and non-rigid motion when the patterns have large amplitude. The velocity-shape process describes the integration of local velocity with shape information, and this depends on the relation between the error in the extraction of the local velocity and the magnitude of the contour amplitude. As a result of these experiments it is conjectured that the velocity-luminance and the velocity-shape processes do interact constructively or destructively. The constructive interaction occurs when the luminance transparency rules are satisfied. The destructive interaction occurs when the luminance transparency rules are violated, and

  16. Lobula-specific visual projection neurons are involved in perception of motion-defined second-order motion in Drosophila.

    Science.gov (United States)

    Zhang, Xiaonan; Liu, He; Lei, Zhengchang; Wu, Zhihua; Guo, Aike

    2013-02-01

    A wide variety of animal species including humans and fruit flies see second-order motion although they lack coherent spatiotemporal correlations in luminance. Recent electrophysiological recordings, together with intensive psychophysical studies, are bringing to light the neural underpinnings of second-order motion perception in mammals. However, where and how the higher-order motion signals are processed in the fly brain is poorly understood. Using the rich genetic tools available in Drosophila and examining optomotor responses in fruit flies to several stimuli, we revealed that two lobula-specific visual projection neurons, specifically connecting the lobula and the central brain, are involved in the perception of motion-defined second-order motion, independent of whether the second-order feature is moving perpendicular or opposite to the local first-order motion. By contrast, blocking these neurons has no effect on first-order and flicker-defined second-order stimuli in terms of response delay. Our results suggest that visual neuropils deep in the optic lobe and the central brain, whose functional roles in motion processing were previously unclear, may be specifically required for motion-defined motion processing.

  17. Being moved by the self and others: influence of empathy on self-motion perception.

    Directory of Open Access Journals (Sweden)

    Christophe Lopez

    Full Text Available BACKGROUND: The observation of conspecifics influences our bodily perceptions and actions: Contagious yawning, contagious itching, or empathy for pain, are all examples of mechanisms based on resonance between our own body and others. While there is evidence for the involvement of the mirror neuron system in the processing of motor, auditory and tactile information, it has not yet been associated with the perception of self-motion. METHODOLOGY/PRINCIPAL FINDINGS: We investigated whether viewing our own body, the body of another, and an object in motion influences self-motion perception. We found a visual-vestibular congruency effect for self-motion perception when observing self and object motion, and a reduction in this effect when observing someone else's body motion. The congruency effect was correlated with empathy scores, revealing the importance of empathy in mirroring mechanisms. CONCLUSIONS/SIGNIFICANCE: The data show that vestibular perception is modulated by agent-specific mirroring mechanisms. The observation of conspecifics in motion is an essential component of social life, and self-motion perception is crucial for the distinction between the self and the other. Finally, our results hint at the presence of a "vestibular mirror neuron system".

  18. Heterosynaptic long-term depression of craniofacial nociception: divergent effects on pain perception and blink reflex in man.

    Science.gov (United States)

    Yekta, Sareh Said; Lamp, Susanne; Ellrich, Jens

    2006-04-01

    Noxious low-frequency stimulation (LFS) of presynaptic nerve fibers induces long-term depression (LTD) of synaptic transmission. In vitro studies suggest a sole homosynaptic effect. Consequently, the present study addressed the hypothesis that LTD of craniofacial nociception in man is mediated by a homosynaptic mechanism. Nociceptive supraorbital afferents were excited by electric pulses via a concentric electrode in ten healthy volunteers. The electrically evoked bilateral blink reflex (BR) was recorded from both orbicularis oculi muscles by surface electrodes. The BR was evoked in blocks of ten electric stimuli each (0.1 Hz) with an interblock interval of 8 min. Conditioning noxious LFS (1 Hz, 20 min) was applied via concentric electrode either to the same site as BR test stimuli (ipsilateral) or to the corresponding contralateral forehead area (contralateral). LFS and test stimulus intensities corresponded to about threefold the pain threshold. After three baseline stimulus blocks, either conditioning ipsilateral or contralateral LFS were applied or stimulation was interrupted for 20 min as a control task. Afterwards, test stimulation blocks were continued for 40 min. Each volunteer participated in all three sessions on different days. Noxious LFS induced LTD of the BR independently from the side of conditioning stimulation. Pain perception decreased after ipsilateral LFS but not after contralateral LFS. The bilateral effect of noxious LFS on the BR provides evidence for heterosynaptic LTD based on bilateral projections of supraorbital nerve afferents onto spinal trigeminal nuclei. The divergent effect on pain perception may be due to a preferential contralateral projection of nociceptive afferents onto reflex interneurons but not onto trigeminothalamic projection neurons.

  19. Three dimensional vestibular ocular reflex testing using a six degrees of freedom motion platform.

    Science.gov (United States)

    Dits, Joyce; Houben, Mark M J; van der Steen, Johannes

    2013-05-23

    The vestibular organ is a sensor that measures angular and linear accelerations with six degrees of freedom (6DF). Complete or partial defects in the vestibular organ results in mild to severe equilibrium problems, such as vertigo, dizziness, oscillopsia, gait unsteadiness nausea and/or vomiting. A good and frequently used measure to quantify gaze stabilization is the gain, which is defined as the magnitude of compensatory eye movements with respect to imposed head movements. To test vestibular function more fully one has to realize that 3D VOR ideally generates compensatory ocular rotations not only with a magnitude (gain) equal and opposite to the head rotation but also about an axis that is co-linear with the head rotation axis (alignment). Abnormal vestibular function thus results in changes in gain and changes in alignment of the 3D VOR response. Here we describe a method to measure 3D VOR using whole body rotation on a 6DF motion platform. Although the method also allows testing translation VOR responses (1), we limit ourselves to a discussion of the method to measure 3D angular VOR. In addition, we restrict ourselves here to description of data collected in healthy subjects in response to angular sinusoidal and impulse stimulation. Subjects are sitting upright and receive whole-body small amplitude sinusoidal and constant acceleration impulses. Sinusoidal stimuli (f = 1 Hz, A = 4°) were delivered about the vertical axis and about axes in the horizontal plane varying between roll and pitch at increments of 22.5° in azimuth. Impulses were delivered in yaw, roll and pitch and in the vertical canal planes. Eye movements were measured using the scleral search coil technique (2). Search coil signals were sampled at a frequency of 1 kHz. The input-output ratio (gain) and misalignment (co-linearity) of the 3D VOR were calculated from the eye coil signals (3). Gain and co-linearity of 3D VOR depended on the orientation of the stimulus axis. Systematic deviations

  20. Influence of Active Manipulation of an Object on Visual Motion Perception

    Directory of Open Access Journals (Sweden)

    Kazumichi Matsumiya

    2011-10-01

    Full Text Available When we manipulate an object by hand, the movements of the object are produced with the visual and haptic movements of our hands. Studies of multimodal perception show the interaction between touch and vision in visual motion perception(1,2. The influence of touch on visual motion perception is shown by the fact that adaptation to tactile motion across the observer's hand induces a visual motion aftereffect, which is a visual illusion in which exposure to a moving visual pattern makes a subsequently viewed stationary visual pattern appear to move in the opposite direction(2. This visuo-tactile interaction plays an important role in skillful manipulation(3. However, it is not clear how haptic information influences visual motion perception. We measured the strength of a visual motion aftereffect after visuo-haptic adaptation to a windmill rotated by observers. We found that the visual motion aftereffect was enhanced when observers actively rotated the windmill. The motion aftereffect was not enhanced when the observer's hand was passively moved. Our results suggest the presence of a visual motion system that is linked to the intended haptic movements.

  1. The visual perception of natural motion: abnormal task-related neural activity in DYT1 dystonia.

    Science.gov (United States)

    Sako, Wataru; Fujita, Koji; Vo, An; Rucker, Janet C; Rizzo, John-Ross; Niethammer, Martin; Carbon, Maren; Bressman, Susan B; Uluğ, Aziz M; Eidelberg, David

    2015-12-01

    Although primary dystonia is defined by its characteristic motor manifestations, non-motor signs and symptoms have increasingly been recognized in this disorder. Recent neuroimaging studies have related the motor features of primary dystonia to connectivity changes in cerebello-thalamo-cortical pathways. It is not known, however, whether the non-motor manifestations of the disorder are associated with similar circuit abnormalities. To explore this possibility, we used functional magnetic resonance imaging to study primary dystonia and healthy volunteer subjects while they performed a motion perception task in which elliptical target trajectories were visually tracked on a computer screen. Prior functional magnetic resonance imaging studies of healthy subjects performing this task have revealed selective activation of motor regions during the perception of 'natural' versus 'unnatural' motion (defined respectively as trajectories with kinematic properties that either comply with or violate the two-thirds power law of motion). Several regions with significant connectivity changes in primary dystonia were situated in proximity to normal motion perception pathways, suggesting that abnormalities of these circuits may also be present in this disorder. To determine whether activation responses to natural versus unnatural motion in primary dystonia differ from normal, we used functional magnetic resonance imaging to study 10 DYT1 dystonia and 10 healthy control subjects at rest and during the perception of 'natural' and 'unnatural' motion. Both groups exhibited significant activation changes across perceptual conditions in the cerebellum, pons, and subthalamic nucleus. The two groups differed, however, in their responses to 'natural' versus 'unnatural' motion in these regions. In healthy subjects, regional activation was greater during the perception of natural (versus unnatural) motion (P perception of unnatural (versus natural) motion (P perception is disrupted in DYT1

  2. Audiovisual associations alter the perception of low-level visual motion

    Directory of Open Access Journals (Sweden)

    Hulusi eKafaligonul

    2015-03-01

    Full Text Available Motion perception is a pervasive nature of vision and is affected by both immediate pattern of sensory inputs and prior experiences acquired through associations. Recently, several studies reported that an association can be established quickly between directions of visual motion and static sounds of distinct frequencies. After the association is formed, sounds are able to change the perceived direction of visual motion. To determine whether such rapidly acquired audiovisual associations and their subsequent influences on visual motion perception are dependent on the involvement of higher-order attentive tracking mechanisms, we designed psychophysical experiments using regular and reverse-phi random dot motions isolating low-level pre-attentive motion processing. Our results show that an association between the directions of low-level visual motion and static sounds can be formed and this audiovisual association alters the subsequent perception of low-level visual motion. These findings support the view that audiovisual associations are not restricted to high-level attention based motion system and early-level visual motion processing has some potential role.

  3. Audiovisual associations alter the perception of low-level visual motion.

    Science.gov (United States)

    Kafaligonul, Hulusi; Oluk, Can

    2015-01-01

    Motion perception is a pervasive nature of vision and is affected by both immediate pattern of sensory inputs and prior experiences acquired through associations. Recently, several studies reported that an association can be established quickly between directions of visual motion and static sounds of distinct frequencies. After the association is formed, sounds are able to change the perceived direction of visual motion. To determine whether such rapidly acquired audiovisual associations and their subsequent influences on visual motion perception are dependent on the involvement of higher-order attentive tracking mechanisms, we designed psychophysical experiments using regular and reverse-phi random dot motions isolating low-level pre-attentive motion processing. Our results show that an association between the directions of low-level visual motion and static sounds can be formed and this audiovisual association alters the subsequent perception of low-level visual motion. These findings support the view that audiovisual associations are not restricted to high-level attention based motion system and early-level visual motion processing has some potential role.

  4. Object manipulation and motion perception: Evidence of an influence of action planning on visual processing

    NARCIS (Netherlands)

    Lindemann, O.; Bekkering, H.

    2009-01-01

    In 3 experiments, the authors investigated the bidirectional coupling of perception and action in the context of object manipulations and motion perception. Participants prepared to grasp an X-shaped object along one of its 2 diagonals and to rotate it in a clockwise or a counterclockwise direction.

  5. The causal relationship between dyslexia and motion perception reconsidered.

    Science.gov (United States)

    Joo, Sung Jun; Donnelly, Patrick M; Yeatman, Jason D

    2017-06-23

    It is well established that visual sensitivity to motion is correlated with reading skills. Yet, the causal relationship between motion sensitivity and reading skills has been debated for more than thirty years. One hypothesis posits that dyslexia is caused by deficits in the motion processing pathway. An alternative hypothesis explains the motion processing deficit observed in dyslexia as the consequence of a lack, or poor quality, of reading experience. Here we used an intensive reading intervention program to test the causal relationship between learning to read and motion processing in children. Our data show that, while the reading intervention enhanced reading abilities, learning to read did not affect motion sensitivity. Motion sensitivity remained stable over the course of the intervention. Furthermore, the motion sensitivity deficit did not negatively impact the learning process. Children with poor motion sensitivity showed the same improvement in reading skills as children with typical motion sensitivity. Our findings call into question the view that motion processing deficits are due to poor reading experience. We propose that the correlation between the two measures arises from other common mechanisms, or that motion processing deficits are among a collection of correlated risk factors for reading difficulties.

  6. Perception model analysis of flight simulator motion for a decrab maneuver

    NARCIS (Netherlands)

    Groen, E.L.; Smaïli, M.H.; Hosman, R.J.A.W.

    2007-01-01

    In this flight simulator study, eleven pilots rated their motion perception during a series of decrab maneuvers of a twin-engine passenger aircraft. Simulator yaw, sway, and roll motion were varied independently to examine their relative contribution to the pilots’ judgments. In one set of condition

  7. Visual processing and social cognition in schizophrenia: relationships among eye movements, biological motion perception, and empathy.

    Science.gov (United States)

    Matsumoto, Yukiko; Takahashi, Hideyuki; Murai, Toshiya; Takahashi, Hidehiko

    2015-01-01

    Schizophrenia patients have impairments at several levels of cognition including visual attention (eye movements), perception, and social cognition. However, it remains unclear how lower-level cognitive deficits influence higher-level cognition. To elucidate the hierarchical path linking deficient cognitions, we focused on biological motion perception, which is involved in both the early stage of visual perception (attention) and higher social cognition, and is impaired in schizophrenia. Seventeen schizophrenia patients and 18 healthy controls participated in the study. Using point-light walker stimuli, we examined eye movements during biological motion perception in schizophrenia. We assessed relationships among eye movements, biological motion perception and empathy. In the biological motion detection task, schizophrenia patients showed lower accuracy and fixated longer than healthy controls. As opposed to controls, patients exhibiting longer fixation durations and fewer numbers of fixations demonstrated higher accuracy. Additionally, in the patient group, the correlations between accuracy and affective empathy index and between eye movement index and affective empathy index were significant. The altered gaze patterns in patients indicate that top-down attention compensates for impaired bottom-up attention. Furthermore, aberrant eye movements might lead to deficits in biological motion perception and finally link to social cognitive impairments. The current findings merit further investigation for understanding the mechanism of social cognitive training and its development. Copyright © 2014 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

  8. An adaptive neural mechanism for acoustic motion perception with varying sparsity

    DEFF Research Database (Denmark)

    Shaikh, Danish; Manoonpong, Poramate

    2017-01-01

    .e. extracting information about its direction and velocity. Here we focus on auditory motion perception of sound stimuli, which is poorly understood as compared to its visual counterpart. In earlier work we have developed a bio-inspired neural learning mechanism for acoustic motion perception. The mechanism...... extracts directional information via a model of the peripheral auditory system of lizards. The mechanism uses only this directional information obtained via specific motor behaviour to learn the angular velocity of unoccluded sound stimuli in motion. In nature however the stimulus being tracked may...... be occluded by artefacts in the environment, such as an escaping prey momentarily disappearing behind a cover of trees. This article extends the earlier work by presenting a comparative investigation of auditory motion perception for unoccluded and occluded tonal sound stimuli with a frequency of 2.2 k...

  9. Multiple-stage ambiguity in motion perception reveals global computation of local motion directions.

    Science.gov (United States)

    Rider, Andrew T; Nishida, Shin'ya; Johnston, Alan

    2016-12-01

    The motion of a 1D image feature, such as a line, seen through a small aperture, or the small receptive field of a neural motion sensor, is underconstrained, and it is not possible to derive the true motion direction from a single local measurement. This is referred to as the aperture problem. How the visual system solves the aperture problem is a fundamental question in visual motion research. In the estimation of motion vectors through integration of ambiguous local motion measurements at different positions, conventional theories assume that the object motion is a rigid translation, with motion signals sharing a common motion vector within the spatial region over which the aperture problem is solved. However, this strategy fails for global rotation. Here we show that the human visual system can estimate global rotation directly through spatial pooling of locally ambiguous measurements, without an intervening step that computes local motion vectors. We designed a novel ambiguous global flow stimulus, which is globally as well as locally ambiguous. The global ambiguity implies that the stimulus is simultaneously consistent with both a global rigid translation and an infinite number of global rigid rotations. By the standard view, the motion should always be seen as a global translation, but it appears to shift from translation to rotation as observers shift fixation. This finding indicates that the visual system can estimate local vectors using a global rotation constraint, and suggests that local motion ambiguity may not be resolved until consistencies with multiple global motion patterns are assessed.

  10. Perception of motion transparency in 5-month-old infants.

    Science.gov (United States)

    Kanazawa, So; Shirai, Nobu; Otsuka, Yumiko; Yamaguchi, Masami K

    2007-01-01

    We investigated the perceptual development of motion transparency in 3- to 5-month-old infants. In two experiments we tested a total of 55 infants and examined their preferential looking behaviour. In experiment 1, we presented transparent motion as a target, and uniform motion as a non-target consisting of random-dot motions. We measured the time during which infants looked at the target and non-target stimuli. In experiment 2, we used paired-dot motions (Qian et al, 1994 Journal of Neuroscience 14 7357-7366) as non-targets and also measured target looking time. We calculated the ratio of the target looking time to the total target and no-target looking time. In both experiments we controlled the dot size, speed, the horizontal travel distance of the dots, and the motion pattern of the dots. The results demonstrated that 5-month-old infants showed a statistically significant preference for motion transparency in almost all stimulus conditions, whereas the preference in 3- and 4-month-old infants depended on stimulus conditions. These results suggest that the sensitivity to motion transparency was robust in 5-month-olds, but not in 3- and 4-month-olds.

  11. Individual differences in the perception of biological motion: links to social cognition and motor imagery.

    Science.gov (United States)

    Miller, Luke E; Saygin, Ayse P

    2013-08-01

    Biological motion perception is often claimed to support social cognition, and to rely upon embodied representations and motor imagery. Are people with higher levels of social traits or more vivid motor imagery better at biological motion perception? We administered four experiments measuring sensitivity in using (global) form and (local) motion cues in biological motion, plus well-established measures of social cognition (e.g., empathy) and motor imagery (e.g., kinesthetic motor imagery). This first systematic investigation of individual variability in biological motion processing demonstrated significant relationships between these domains, along with a dissociation. Sensitivity for using form cues in biological motion processing was correlated with social (and not the imagery) measures; sensitivity for using motion cues was correlated with motor imagery (and not the social) measures. These results could not be explained by performance on non-biological control stimuli. We thus show that although both social cognition and motor imagery predict sensitivity to biological motion, these skills likely tap into different aspects of perception. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Modulating irrelevant motion perception by varying attentional load in an unrelated task.

    Science.gov (United States)

    Rees, G; Frith, C D; Lavie, N

    1997-11-28

    Lavie's theory of attention proposes that the processing load in a relevant task determines the extent to which irrelevant distractors are processed. This theory was tested by asking participants in a study to perform linguistic tasks of low or high load while ignoring irrelevant visual motion in the periphery of the display. Although task and distractor were unrelated, both functional imaging of motion-related activity in cortical area V5 and psychophysical measures of the motion aftereffect showed reduced motion processing during high load in the linguistic task. These findings fulfill the prediction that perception of irrelevant distractors depends on the relevant processing load.

  13. Primary visual cortex activity along the apparent-motion trace reflects illusory perception.

    Directory of Open Access Journals (Sweden)

    Lars Muckli

    2005-08-01

    Full Text Available The illusion of apparent motion can be induced when visual stimuli are successively presented at different locations. It has been shown in previous studies that motion-sensitive regions in extrastriate cortex are relevant for the processing of apparent motion, but it is unclear whether primary visual cortex (V1 is also involved in the representation of the illusory motion path. We investigated, in human subjects, apparent-motion-related activity in patches of V1 representing locations along the path of illusory stimulus motion using functional magnetic resonance imaging. Here we show that apparent motion caused a blood-oxygenation-level-dependent response along the V1 representations of the apparent-motion path, including regions that were not directly activated by the apparent-motion-inducing stimuli. This response was unaltered when participants had to perform an attention-demanding task that diverted their attention away from the stimulus. With a bistable motion quartet, we confirmed that the activity was related to the conscious perception of movement. Our data suggest that V1 is part of the network that represents the illusory path of apparent motion. The activation in V1 can be explained either by lateral interactions within V1 or by feedback mechanisms from higher visual areas, especially the motion-sensitive human MT/V5 complex.

  14. Tuning self-motion perception in virtual reality with visual illusions.

    Science.gov (United States)

    Bruder, Gerd; Steinicke, Frank; Wieland, Phil; Lappe, Markus

    2012-07-01

    Motion perception in immersive virtual environments significantly differs from the real world. For example, previous work has shown that users tend to underestimate travel distances in virtual environments (VEs). As a solution to this problem, researchers proposed to scale the mapped virtual camera motion relative to the tracked real-world movement of a user until real and virtual motion are perceived as equal, i.e., real-world movements could be mapped with a larger gain to the VE in order to compensate for the underestimation. However, introducing discrepancies between real and virtual motion can become a problem, in particular, due to misalignments of both worlds and distorted space cognition. In this paper, we describe a different approach that introduces apparent self-motion illusions by manipulating optic flow fields during movements in VEs. These manipulations can affect self-motion perception in VEs, but omit a quantitative discrepancy between real and virtual motions. In particular, we consider to which regions of the virtual view these apparent self-motion illusions can be applied, i.e., the ground plane or peripheral vision. Therefore, we introduce four illusions and show in experiments that optic flow manipulation can significantly affect users' self-motion judgments. Furthermore, we show that with such manipulations of optic flow fields the underestimation of travel distances can be compensated.

  15. Perception of social interactions for spatially scrambled biological motion.

    Science.gov (United States)

    Thurman, Steven M; Lu, Hongjing

    2014-01-01

    It is vitally important for humans to detect living creatures in the environment and to analyze their behavior to facilitate action understanding and high-level social inference. The current study employed naturalistic point-light animations to examine the ability of human observers to spontaneously identify and discriminate socially interactive behaviors between two human agents. Specifically, we investigated the importance of global body form, intrinsic joint movements, extrinsic whole-body movements, and critically, the congruency between intrinsic and extrinsic motions. Motion congruency is hypothesized to be particularly important because of the constraint it imposes on naturalistic action due to the inherent causal relationship between limb movements and whole body motion. Using a free response paradigm in Experiment 1, we discovered that many naïve observers (55%) spontaneously attributed animate and/or social traits to spatially-scrambled displays of interpersonal interaction. Total stimulus motion energy was strongly correlated with the likelihood that an observer would attribute animate/social traits, as opposed to physical/mechanical traits, to the scrambled dot stimuli. In Experiment 2, we found that participants could identify interactions between spatially-scrambled displays of human dance as long as congruency was maintained between intrinsic/extrinsic movements. Violating the motion congruency constraint resulted in chance discrimination performance for the spatially-scrambled displays. Finally, Experiment 3 showed that scrambled point-light dancing animations violating this constraint were also rated as significantly less interactive than animations with congruent intrinsic/extrinsic motion. These results demonstrate the importance of intrinsic/extrinsic motion congruency for biological motion analysis, and support a theoretical framework in which early visual filters help to detect animate agents in the environment based on several fundamental

  16. Effects of Frequency and Motion Paradigm on Perception of Tilt and Translation During Periodic Linear Acceleration

    Science.gov (United States)

    Beaton, K. H.; Holly, J. E.; Clement, G. R.; Wood, Scott J.

    2009-01-01

    Previous studies have demonstrated an effect of frequency on the gain of tilt and translation perception. Results from different motion paradigms are often combined to extend the stimulus frequency range. For example, Off-Vertical Axis Rotation (OVAR) and Variable Radius Centrifugation (VRC) are useful to test low frequencies of linear acceleration at amplitudes that would require impractical sled lengths. The purpose of this study was to compare roll-tilt and lateral translation motion perception in 12 healthy subjects across four paradigms: OVAR, VRC, sled translation and rotation about an earth-horizontal axis. Subjects were oscillated in darkness at six frequencies from 0.01875 to 0.6 Hz (peak acceleration equivalent to 10 deg, less for sled motion below 0.15 Hz). Subjects verbally described the amplitude of perceived tilt and translation, and used a joystick to indicate the direction of motion. Consistent with previous reports, tilt perception gain decreased as a function of stimulus frequency in the motion paradigms without concordant canal tilt cues (OVAR, VRC and Sled). Translation perception gain was negligible at low stimulus frequencies and increased at higher frequencies. There were no significant differences between the phase of tilt and translation, nor did the phase significantly vary across stimulus frequency. There were differences in perception gain across the different paradigms. Paradigms that included actual tilt stimuli had the larger tilt gains, and paradigms that included actual translation stimuli had larger translation gains. In addition, the frequency at which there was a crossover of tilt and translation gains appeared to vary across motion paradigm between 0.15 and 0.3 Hz. Since the linear acceleration in the head lateral plane was equivalent across paradigms, differences in gain may be attributable to the presence of linear accelerations in orthogonal directions and/or cognitive aspects based on the expected motion paths.

  17. Behavioral Differences in the Upper and Lower Visual Hemifields in Shape and Motion Perception.

    Science.gov (United States)

    Zito, Giuseppe A; Cazzoli, Dario; Müri, René M; Mosimann, Urs P; Nef, Tobias

    2016-01-01

    Perceptual accuracy is known to be influenced by stimuli location within the visual field. In particular, it seems to be enhanced in the lower visual hemifield (VH) for motion and space processing, and in the upper VH for object and face processing. The origins of such asymmetries are attributed to attentional biases across the visual field, and in the functional organization of the visual system. In this article, we tested content-dependent perceptual asymmetries in different regions of the visual field. Twenty-five healthy volunteers participated in this study. They performed three visual tests involving perception of shapes, orientation and motion, in the four quadrants of the visual field. The results of the visual tests showed that perceptual accuracy was better in the lower than in the upper visual field for motion perception, and better in the upper than in the lower visual field for shape perception. Orientation perception did not show any vertical bias. No difference was found when comparing right and left VHs. The functional organization of the visual system seems to indicate that the dorsal and the ventral visual streams, responsible for motion and shape perception, respectively, show a bias for the lower and upper VHs, respectively. Such a bias depends on the content of the visual information.

  18. Comparison of Flight Simulators Based on Human Motion Perception Metrics

    Science.gov (United States)

    Valente Pais, Ana R.; Correia Gracio, Bruno J.; Kelly, Lon C.; Houck, Jacob A.

    2015-01-01

    In flight simulation, motion filters are used to transform aircraft motion into simulator motion. When looking for the best match between visual and inertial amplitude in a simulator, researchers have found that there is a range of inertial amplitudes, rather than a single inertial value, that is perceived by subjects as optimal. This zone, hereafter referred to as the optimal zone, seems to correlate to the perceptual coherence zones measured in flight simulators. However, no studies were found in which these two zones were compared. This study investigates the relation between the optimal and the coherence zone measurements within and between different simulators. Results show that for the sway axis, the optimal zone lies within the lower part of the coherence zone. In addition, it was found that, whereas the width of the coherence zone depends on the visual amplitude and frequency, the width of the optimal zone remains constant.

  19. Two independent mechanisms for motion-in-depth perception: evidence from individual differences

    Directory of Open Access Journals (Sweden)

    Harold T Nefs

    2010-10-01

    Full Text Available Our forward-facing eyes allow us the advantage of binocular visual information: using the tiny differences between right and left eye views to learn about depth and location in three dimensions. Our visual systems also contain specialized mechanisms to detect motion-in-depth from binocular vision, but the nature of these mechanisms remains controversial. Binocular motion-in-depth perception could theoretically be based on first detecting binocular disparity and then monitoring how it changes over time. The alternative is to monitor the motion in the right and left eye separately and then compare these motion signals. Here we used an individual differences approach to test whether the two sources of information are processed via dissociated mechanisms, and to measure the relative importance of those mechanisms. Our results suggest the existence of two distinct mechanisms, each contributing to the perception of motion in depth in most observers. Additionally, for the first time, we demonstrate the relative prevalence of the two mechanisms within a normal population. In general, visual systems appear to rely mostly on the mechanism sensitive to changing binocular disparity, but perception of motion in depth is augmented by the presence of a less sensitive mechanism that uses interocular velocity differences. Occasionally, we find observers with the opposite pattern of sensitivity. More generally this work showcases the power of the individual differences approach in studying the functional organisation of cognitive systems.

  20. Deciding what to see: the role of intention and attention in the perception of apparent motion.

    Science.gov (United States)

    Kohler, Axel; Haddad, Leila; Singer, Wolf; Muckli, Lars

    2008-03-01

    Apparent motion is an illusory perception of movement that can be induced by alternating presentations of static objects. Already in Wertheimer's early investigation of the phenomenon [Wertheimer, M. (1912). Experimentelle Studien über das Sehen von Bewegung. Zeitschrift fur Psychologie, 61, 161-265], he mentions that voluntary attention can influence the way in which an ambiguous apparent motion display is perceived. But until now, few studies have investigated how strong the modulation of apparent motion through attention can be under different stimulus and task conditions. We used bistable motion quartets of two different sizes, where the perception of vertical and horizontal motion is equally likely. Eleven observers participated in two experiments. In Experiment 1, participants were instructed to either (a) hold the current movement direction as long as possible, (b) passively view the stimulus, or (c) switch the movement directions as quickly as possible. With the respective instructions, observers could almost double phase durations in (a) and more than halve durations in (c) relative to the passive condition. This modulation effect was stronger for the large quartets. In Experiment 2, observers' attention was diverted from the stimulus by a detection task at fixation while they still had to report their conscious perception. This manipulation prolonged dominance durations for up to 100%. The experiments reveal a high susceptibility of ambiguous apparent motion to attentional modulation. We discuss how feature- and space-based attention mechanisms might contribute to those effects.

  1. S1-3: Perception of Biological Motion in Schizophrenia and Obsessive-Compulsive Disorder

    Directory of Open Access Journals (Sweden)

    Jejoong Kim

    2012-10-01

    Full Text Available Major mental disorders including schizophrenia, autism, and obsessive-compulsive disorder (OCD are characterized by impaired social functioning regardless of wide range of clinical symptoms. Past studies also revealed that people with these mental illness exhibit perceptual problems with altered neural activation. For example, schizophrenia patients are deficient in processing rapid and dynamic visual stimuli. As well documented, people are very sensitive to motion signals generated by others (i.e., biological motion even when those motions are portrayed by point-light display. Therefore, ability to perceive biological motion is important for both visual perception and social functioning. Nevertheless, there have been no systematic attempts to investigate biological motion perception in people with mental illness associated with impaired social functioning until a decade ago. Recently, a series of studies newly revealed abnormal patterns of biological motion perception and associated neural activations in schizophrenia and OCD. These new achievements will be reviewed focusing on perceptual and neural difference between patients with schizophrenia/OCD and healthy individuals. Then implications and possible future research will be discussed in this talk.

  2. The cortical topography of self-motion perception.

    NARCIS (Netherlands)

    Arnoldussen, D.M.

    2015-01-01

    When performing motor actions such as picking up a cup from a table we need to have reliable information about the location and size of the object. However, most actions are performed while we are in motion, meaning that the change in our position relative to our surroundings needs to be

  3. The cortical topography of self-motion perception.

    NARCIS (Netherlands)

    Arnoldussen, D.M.

    2015-01-01

    When performing motor actions such as picking up a cup from a table we need to have reliable information about the location and size of the object. However, most actions are performed while we are in motion, meaning that the change in our position relative to our surroundings needs to be incorporate

  4. Residual perception of biological motion in cortical blindness.

    Science.gov (United States)

    Ruffieux, Nicolas; Ramon, Meike; Lao, Junpeng; Colombo, Françoise; Stacchi, Lisa; Borruat, François-Xavier; Accolla, Ettore; Annoni, Jean-Marie; Caldara, Roberto

    2016-12-01

    From birth, the human visual system shows a remarkable sensitivity for perceiving biological motion. This visual ability relies on a distributed network of brain regions and can be preserved even after damage of high-level ventral visual areas. However, it remains unknown whether this critical biological skill can withstand the loss of vision following bilateral striate damage. To address this question, we tested the categorization of human and animal biological motion in BC, a rare case of cortical blindness after anoxia-induced bilateral striate damage. The severity of his impairment, encompassing various aspects of vision (i.e., color, shape, face, and object recognition) and causing blind-like behavior, contrasts with a residual ability to process motion. We presented BC with static or dynamic point-light displays (PLDs) of human or animal walkers. These stimuli were presented either individually, or in pairs in two alternative forced choice (2AFC) tasks. When confronted with individual PLDs, the patient was unable to categorize the stimuli, irrespective of whether they were static or dynamic. In the 2AFC task, BC exhibited appropriate eye movements towards diagnostic information, but performed at chance level with static PLDs, in stark contrast to his ability to efficiently categorize dynamic biological agents. This striking ability to categorize biological motion provided top-down information is important for at least two reasons. Firstly, it emphasizes the importance of assessing patients' (visual) abilities across a range of task constraints, which can reveal potential residual abilities that may in turn represent a key feature for patient rehabilitation. Finally, our findings reinforce the view that the neural network processing biological motion can efficiently operate despite severely impaired low-level vision, positing our natural predisposition for processing dynamicity in biological agents as a robust feature of human vision.

  5. Values, antivalues and feelings transmitted by the media and its reflexive perception

    Directory of Open Access Journals (Sweden)

    Donaciano BARTOLOMÉ CRESPO

    2009-11-01

    Full Text Available This research deals with the perception of values, antivalues and feelings incarnated and manifested in images, words and sounds self introduced or mediated. If in the past media and their messages have been studied, the current concern of the majority would be to investigate what happens inside the individual, how he or she reacts, what are his /her feelings. There is no doubt that the reflection about values an own feelings that listening, looking or reading news create, is a very attractive and prommising field. But as the ethical principles which media should serve can vary and even contradict each other, the modern teacher schould be aware of it in order not to assing roles and functions that do not fit whit the media. However it is always his/her concern from his/her educative function to anlyze and penetrate into the messages that circulate in society through the omnipresent mass media. Tis study stands out with level and scientific rigueur what is generally and commonly known. All the calls made by Government, authorities, institutions, and people for a better quality'vs media where it would not be be propagation or apology of antivalues such as paradigms of behavior, should make the responsible of media think over to study and deeply change according to the new funktions in a new society where philosophy and medias programming.

  6. Modification of Motion Perception and Manual Control Following Short-Durations Spaceflight

    Science.gov (United States)

    Wood, S. J.; Vanya, R. D.; Esteves, J. T.; Rupert, A. H.; Clement, G.

    2011-01-01

    Adaptive changes during space flight in how the brain integrates vestibular cues with other sensory information can lead to impaired movement coordination and spatial disorientation following G-transitions. This ESA-NASA study was designed to examine both the physiological basis and operational implications for disorientation and tilt-translation disturbances following short-duration spaceflights. The goals of this study were to (1) examine the effects of stimulus frequency on adaptive changes in motion perception during passive tilt and translation motion, (2) quantify decrements in manual control of tilt motion, and (3) evaluate vibrotactile feedback as a sensorimotor countermeasure.

  7. Deficits of motion transparency perception in adult developmental dyslexics with normal unidirectional motion sensitivity.

    Science.gov (United States)

    Hill, Gary T; Raymond, Jane E

    2002-04-01

    We assessed motion integration ability in seven adult developmental dyslexics using unidirectional and bidirectional (transparent) random dot kinematograms (RDKs) that varied in the number of frames. All adult dyslexics performed as well as normally reading age-matched controls with unidirectional RDKs, regardless of frame number. However, using orthogonal motion transparent stimuli, deficits were obvious in six dyslexics and depended on frame number. Whereas controls needed on average only 4.4 frames (144 ms) to identify both directions correctly on 75% of presentations, dyslexics needed on average 14.6 frames (483 ms) to achieve this level of performance. Even though a unidirectional motion task failed to reveal processing abnormalities in adult dyslexics, the motion transparency task was effective at revealing significant perceptual dysfunction, suggesting that performance on this task is a better psychophysical indicator of visual motion deficits in dyslexia. This finding provides little support for the magnocellular deficit hypothesis and, rather, points to abnormality within dorsal extrastriate cortical areas that subserve the integration and segmentation of complex motion signals.

  8. What women like: influence of motion and form on esthetic body perception

    Directory of Open Access Journals (Sweden)

    Valentina eCazzato

    2012-07-01

    Full Text Available Several studies have shown the distinct contribution of motion and form to the esthetic evaluation of female bodies. Here, we investigated how variations of implied motion and body size interact in the esthetic evaluation of female and male bodies in a sample of young healthy women. Participants provided attractiveness, beauty, and liking ratings for the shape and posture of virtual renderings of human bodies with variable body size and implied motion. The esthetic judgments for both shape and posture of human models were influenced by body size and implied motion, with a preference for thinner and more dynamic stimuli. Implied motion, however, attenuated the impact of extreme body size on the esthetic evaluation of body postures, and body size variations did not affect the preference for more dynamic stimuli. Results show that body form and action cues interact in esthetic perception, but the final esthetic appreciation of human bodies is predicted by a mixture of perceptual and affective evaluative components.

  9. The effect of occlusion therapy on motion perception deficits in amblyopia.

    Science.gov (United States)

    Giaschi, Deborah; Chapman, Christine; Meier, Kimberly; Narasimhan, Sathyasri; Regan, David

    2015-09-01

    There is growing evidence for deficits in motion perception in amblyopia, but these are rarely assessed clinically. In this prospective study we examined the effect of occlusion therapy on motion-defined form perception and multiple-object tracking. Participants included children (3-10years old) with unilateral anisometropic and/or strabismic amblyopia who were currently undergoing occlusion therapy and age-matched control children with normal vision. At the start of the study, deficits in motion-defined form perception were present in at least one eye in 69% of the children with amblyopia. These deficits were still present at the end of the study in 55% of the amblyopia group. For multiple-object tracking, deficits were present initially in 64% and finally in 55% of the children with amblyopia, even after completion of occlusion therapy. Many of these deficits persisted in spite of an improvement in amblyopic eye visual acuity in response to occlusion therapy. The prevalence of motion perception deficits in amblyopia as well as their resistance to occlusion therapy, support the need for new approaches to amblyopia treatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Perception of biological motion in schizophrenia and healthy individuals: a behavioral and FMRI study.

    Directory of Open Access Journals (Sweden)

    Jejoong Kim

    Full Text Available BACKGROUND: Anomalous visual perception is a common feature of schizophrenia plausibly associated with impaired social cognition that, in turn, could affect social behavior. Past research suggests impairment in biological motion perception in schizophrenia. Behavioral and functional magnetic resonance imaging (fMRI experiments were conducted to verify the existence of this impairment, to clarify its perceptual basis, and to identify accompanying neural concomitants of those deficits. METHODOLOGY/FINDINGS: In Experiment 1, we measured ability to detect biological motion portrayed by point-light animations embedded within masking noise. Experiment 2 measured discrimination accuracy for pairs of point-light biological motion sequences differing in the degree of perturbation of the kinematics portrayed in those sequences. Experiment 3 measured BOLD signals using event-related fMRI during a biological motion categorization task. Compared to healthy individuals, schizophrenia patients performed significantly worse on both the detection (Experiment 1 and discrimination (Experiment 2 tasks. Consistent with the behavioral results, the fMRI study revealed that healthy individuals exhibited strong activation to biological motion, but not to scrambled motion in the posterior portion of the superior temporal sulcus (STSp. Interestingly, strong STSp activation was also observed for scrambled or partially scrambled motion when the healthy participants perceived it as normal biological motion. On the other hand, STSp activation in schizophrenia patients was not selective to biological or scrambled motion. CONCLUSION: Schizophrenia is accompanied by difficulties discriminating biological from non-biological motion, and associated with those difficulties are altered patterns of neural responses within brain area STSp. The perceptual deficits exhibited by schizophrenia patients may be an exaggerated manifestation of neural events within STSp associated with

  11. Variations in gravitoinertial force level affect the gain of the vestibulo-ocular reflex - Implications of the etiology of space motion sickness

    Science.gov (United States)

    Lackner, J. R.; Graybiel, A.

    1981-01-01

    Recordings of horizontal nystagmus were obtained on 16 male subjects exposed to repeated patterns of horizontal angular acceleration, constant velocity rotation, and sudden-stop deceleration in the laboratory and in the free-fall and high-force periods of parabolic flight. Nystagmus intensity was a clear function of gravitoinertial force level: slow phase velocity and beat frequency increased during exposure to high force levels and decreased in free-fall compared to values obtained at 1 G. These findings indicate that the gain of the vestibulo-ocular reflex decreases in free-fall. This fact likely accounts for the disorientation and dizziness sometimes experienced by astronauts when moving their heads in the early phases of orbital flight and again after splashdown. The implications of the present findings, both for the etiology and for the treatment of space motion sickness, are discussed.

  12. An adaptive neural mechanism for acoustic motion perception with varying sparsity

    DEFF Research Database (Denmark)

    Shaikh, Danish; Manoonpong, Poramate

    2017-01-01

    extracts directional information via a model of the peripheral auditory system of lizards. The mechanism uses only this directional information obtained via specific motor behaviour to learn the angular velocity of unoccluded sound stimuli in motion. In nature however the stimulus being tracked may.......e. extracting information about its direction and velocity. Here we focus on auditory motion perception of sound stimuli, which is poorly understood as compared to its visual counterpart. In earlier work we have developed a bio-inspired neural learning mechanism for acoustic motion perception. The mechanism......Hz in both simulation and practice. Three instances of each stimuli are employed, differing in their movement velocities–0.5 deg / time step, 1.0 deg / time step and 1.5 deg / time step. To validate the approach in practice, we implement the proposed neural mechanism on a wheeled mobile robot and evaluate...

  13. Development of visual motion perception for prospective control: Brain and behavioural studies in infants

    Directory of Open Access Journals (Sweden)

    Seth B. Agyei

    2016-02-01

    Full Text Available During infancy, smart perceptual mechanisms develop allowing infants to judge time-space motion dynamics more efficiently with age and locomotor experience. This emerging capacity may be vital to enable preparedness for upcoming events and to be able to navigate in a changing environment. Little is known about brain changes that support the development of prospective control and about processes, such as preterm birth, that may compromise it. As a function of perception of visual motion, this paper will describe behavioural and brain studies with young infants investigating the development of visual perception for prospective control. By means of the three visual motion paradigms of occlusion, looming, and optic flow, our research shows the importance of including behavioural data when studying the neural correlates of prospective control.

  14. Motion Perception and Manual Control Performance During Passive Tilt and Translation Following Space Flight

    Science.gov (United States)

    Clement, Gilles; Wood, Scott J.

    2010-01-01

    This joint ESA-NASA study is examining changes in motion perception following Space Shuttle flights and the operational implications of post-flight tilt-translation ambiguity for manual control performance. Vibrotactile feedback of tilt orientation is also being evaluated as a countermeasure to improve performance during a closed-loop nulling task. METHODS. Data has been collected on 5 astronaut subjects during 3 preflight sessions and during the first 8 days after Shuttle landings. Variable radius centrifugation (216 deg/s) combined with body translation (12-22 cm, peak-to-peak) is utilized to elicit roll-tilt perception (equivalent to 20 deg, peak-to-peak). A forward-backward moving sled (24-390 cm, peak-to-peak) with or without chair tilting in pitch is utilized to elicit pitch tilt perception (equivalent to 20 deg, peak-to-peak). These combinations are elicited at 0.15, 0.3, and 0.6 Hz for evaluating the effect of motion frequency on tilt-translation ambiguity. In both devices, a closed-loop nulling task is also performed during pseudorandom motion with and without vibrotactile feedback of tilt. All tests are performed in complete darkness. PRELIMINARY RESULTS. Data collection is currently ongoing. Results to date suggest there is a trend for translation motion perception to be increased at the low and medium frequencies on landing day compared to pre-flight. Manual control performance is improved with vibrotactile feedback. DISCUSSION. The results of this study indicate that post-flight recovery of motion perception and manual control performance is complete within 8 days following short-duration space missions. Vibrotactile feedback of tilt improves manual control performance both before and after flight.

  15. Tessellated structure from motion for midrange perception and tactical planning

    Science.gov (United States)

    Shim, Minbo; Yilma, Samson

    2009-05-01

    A typical structure from motion (SFM) technique is to construct 3-D structures from the observation of the motions of salient features tracked over time. Although the sparse feature-based SFM provides additional solutions to robotic platforms as a tool to augment navigation performance, the technique often fails to produce dense 3-D structures due to the sparseness that is introduced during the feature selection and matching processes. For midrange sensing and tactical planning, it is important to have a dense map that is able to provide not only 3-D coordinates of features, but also clustered terrain information around the features for better thematic representation of the scene. In order to overcome the shortfalls embedded in the sparse feature-based SFM, we propose an approach that uses Voronoi decomposition with an equidistance-based triangulation that is applied to each of segmented and classified regions. The set of the circumcenters of the circum-hyperspheres used in the triangulation is formed with the feature points extracted from the SFM processing. We also apply flat surface detection to find traversable surface for a robotic vehicle to be able to maneuver safely on.

  16. Aging deteriorated perception of urge-to-cough without changing cough reflex threshold to citric acid in female never-smokers

    OpenAIRE

    Ebihara, Satoru; Ebihara, Takae; Kanezaki, Masashi; Gui, Peijun; Yamasaki, Miyako; Arai, Hiroyuki; Kohzuki, Masahiro

    2011-01-01

    Background The effect of aging on the cognitive aspect of cough has not been studied yet. The purpose of this study is to investigate the aging effect on the perception of urge-to-cough in healthy individuals. Methods Fourteen young, female, healthy never-smokers were recruited via public postings. Twelve elderly female healthy never-smokers were recruited from a nursing home residence. The cough reflex threshold and the urge-to-cough were evaluated by inhalation of citric acid. The cough ref...

  17. Unaffected perceptual thresholds for biological and non-biological form-from-motion perception in autism spectrum conditions.

    Directory of Open Access Journals (Sweden)

    Ayse Pinar Saygin

    Full Text Available BACKGROUND: Perception of biological motion is linked to the action perception system in the human brain, abnormalities within which have been suggested to underlie impairments in social domains observed in autism spectrum conditions (ASC. However, the literature on biological motion perception in ASC is heterogeneous and it is unclear whether deficits are specific to biological motion, or might generalize to form-from-motion perception. METHODOLOGY AND PRINCIPAL FINDINGS: We compared psychophysical thresholds for both biological and non-biological form-from-motion perception in adults with ASC and controls. Participants viewed point-light displays depicting a walking person (Biological Motion, a translating rectangle (Structured Object or a translating unfamiliar shape (Unstructured Object. The figures were embedded in noise dots that moved similarly and the task was to determine direction of movement. The number of noise dots varied on each trial and perceptual thresholds were estimated adaptively. We found no evidence for an impairment in biological or non-biological object motion perception in individuals with ASC. Perceptual thresholds in the three conditions were almost identical between the ASC and control groups. DISCUSSION AND CONCLUSIONS: Impairments in biological motion and non-biological form-from-motion perception are not across the board in ASC, and are only found for some stimuli and tasks. We discuss our results in relation to other findings in the literature, the heterogeneity of which likely relates to the different tasks performed. It appears that individuals with ASC are unaffected in perceptual processing of form-from-motion, but may exhibit impairments in higher order judgments such as emotion processing. It is important to identify more specifically which processes of motion perception are impacted in ASC before a link can be made between perceptual deficits and the higher-level features of the disorder.

  18. Revisiting the importance of common body motion in human action perception.

    Science.gov (United States)

    Thurman, Steven M; Lu, Hongjing

    2016-01-01

    Human actions are complex dynamic stimuli comprised of two principle motion components: 1) common body motion, which represents the translation of the body when a person moves through space, and 2) relative limb movements, resulting from articulation of limbs after factoring out common body motion. Historically, most research in biological motion has focused primarily on relative limb movements while discounting the role of common body motion in human action perception. The current study examined the relative contribution of posture change resulting from relative limb movements and translation of body position resulting from common body motion in discriminating human walking versus running actions. We found that faster translation speeds of common body motion evoked significantly more responses consistent with running when discriminating ambiguous actions morphed between walking and running. Furthermore, this influence was systematically modulated by the uncertainty associated with intrinsic cues as determined by the degree of limited-lifetime spatial sampling. The contribution of common body motion increased monotonically as the reliability of inferring posture changes on the basis of intrinsic cues decreased. These results highlight the importance of translational body movements and their interaction with posture change as a result of relative limb movements in discriminating human actions when visual input information is sparse and noisy.

  19. When brain damage "improves" perception: neglect patients can localize motion-shifted probes better than controls.

    Science.gov (United States)

    de Vito, Stefania; Lunven, Marine; Bourlon, Clémence; Duret, Christophe; Cavanagh, Patrick; Bartolomeo, Paolo

    2015-12-01

    When we look at bars flashed against a moving background, we see them displaced in the direction of the upcoming motion (flash-grab illusion). It is still debated whether these motion-induced position shifts are low-level, reflexive consequences of stimulus motion or high-level compensation engaged only when the stimulus is tracked with attention. To investigate whether attention is a causal factor for this striking illusory position shift, we evaluated the flash-grab illusion in six patients with damaged attentional networks in the right hemisphere and signs of left visual neglect and six age-matched controls. With stimuli in the top, right, and bottom visual fields, neglect patients experienced the same amount of illusion as controls. However, patients showed no significant shift when the test was presented in their left hemifield, despite having equally precise judgments. Thus, paradoxically, neglect patients perceived the position of the flash more veridically in their neglected hemifield. These results suggest that impaired attentional processes can reduce the interaction between a moving background and a superimposed stationary flash, and indicate that attention is a critical factor in generating the illusory motion-induced shifts of location.

  20. Global motion perception is independent from contrast sensitivity for coherent motion direction discrimination and visual acuity in 4.5-year-old children.

    Science.gov (United States)

    Chakraborty, Arijit; Anstice, Nicola S; Jacobs, Robert J; Paudel, Nabin; LaGasse, Linda L; Lester, Barry M; Wouldes, Trecia A; Harding, Jane E; Thompson, Benjamin

    2015-10-01

    Global motion processing depends on a network of brain regions that includes extrastriate area V5 in the dorsal visual stream. For this reason, psychophysical measures of global motion perception have been used to provide a behavioral measure of dorsal stream function. This approach assumes that global motion is relatively independent of visual functions that arise earlier in the visual processing hierarchy such as contrast sensitivity and visual acuity. We tested this assumption by assessing the relationships between global motion perception, contrast sensitivity for coherent motion direction discrimination (henceforth referred to as contrast sensitivity) and habitual visual acuity in a large group of 4.5-year-old children (n=117). The children were born at risk of abnormal neurodevelopment because of prenatal drug exposure or risk factors for neonatal hypoglycemia. Motion coherence thresholds, a measure of global motion perception, were assessed using random dot kinematograms. The contrast of the stimuli was fixed at 100% and coherence was varied. Contrast sensitivity was measured using the same stimuli by fixing motion coherence at 100% and varying dot contrast. Stereoacuity was also measured. Motion coherence thresholds were not correlated with contrast sensitivity or visual acuity. However, lower (better) motion coherence thresholds were correlated with finer stereoacuity (ρ=0.38, p=0.004). Contrast sensitivity and visual acuity were also correlated (ρ=-0.26, p=0.004) with each other. These results indicate that global motion perception for high contrast stimuli is independent of contrast sensitivity and visual acuity and can be used to assess motion integration mechanisms in children.

  1. The visual perception of motion by observers with autism spectrum disorders: a review and synthesis.

    Science.gov (United States)

    Kaiser, Martha D; Shiffrar, Maggie

    2009-10-01

    Traditionally, psychological research on autism spectrum disorder (ASD) has focused on social and cognitive abilities. Vision provides an important input channel to both of these processes, and, increasingly, researchers are investigating whether observers with ASD differ from typical observers in their visual percepts. Recently, significant controversies have arisen over whether observers with ASD differ from typical observers in their visual analyses of movement. Initial studies suggested that observers with ASD experience significant deficits in their visual sensitivity to coherent motion in random dot displays but not to point-light displays of human motion. More recent evidence suggests exactly the opposite: that observers with ASD do not differ from typical observers in their visual sensitivity to coherent motion in random dot displays, but do differ from typical observers in their visual sensitivity to human motion. This review examines these apparently conflicting results, notes gaps in previous findings, suggests a potentially unifying hypothesis, and identifies areas ripe for future research.

  2. Psilocybin impairs high-level but not low-level motion perception.

    Science.gov (United States)

    Carter, Olivia L; Pettigrew, John D; Burr, David C; Alais, David; Hasler, Felix; Vollenweider, Franz X

    2004-08-26

    The hallucinogenic serotonin(1A&2A) agonist psilocybin is known for its ability to induce illusions of motion in otherwise stationary objects or textured surfaces. This study investigated the effect of psilocybin on local and global motion processing in nine human volunteers. Using a forced choice direction of motion discrimination task we show that psilocybin selectively impairs coherence sensitivity for random dot patterns, likely mediated by high-level global motion detectors, but not contrast sensitivity for drifting gratings, believed to be mediated by low-level detectors. These results are in line with those observed within schizophrenic populations and are discussed in respect to the proposition that psilocybin may provide a model to investigate clinical psychosis and the pharmacological underpinnings of visual perception in normal populations.

  3. AMPUTATION AND REFLEX SYMPATHETIC DYSTROPHY

    NARCIS (Netherlands)

    GEERTZEN, JHB; EISMA, WH

    Reflex sympathetic dystrophy is a chronic pain syndrome characterized by chronic burning pain, restricted range of motion, oedema and vasolability. Patients are difficult to treat and the prognosis is very often poor. This report emphasizes that an amputation in case of a reflex sympathetic

  4. Touching motion: rTMS on the human middle temporal complex interferes with tactile speed perception.

    Science.gov (United States)

    Basso, Demis; Pavan, Andrea; Ricciardi, Emiliano; Fagioli, Sabrina; Vecchi, Tomaso; Miniussi, Carlo; Pietrini, Pietro

    2012-10-01

    Brain functional and psychophysical studies have clearly demonstrated that visual motion perception relies on the activity of the middle temporal complex (hMT+). However, recent studies have shown that hMT+ seems to be also activated during tactile motion perception, suggesting that this visual extrastriate area is involved in the processing and integration of motion, irrespective of the sensorial modality. In the present study, we used repetitive transcranial magnetic stimulation (rTMS) to assess whether hMT+ plays a causal role in tactile motion processing. Blindfolded participants detected changes in the speed of a grid of tactile moving points with their finger (i.e. tactile modality). The experiment included three different conditions: a control condition with no TMS and two TMS conditions, i.e. hMT+-rTMS and posterior parietal cortex (PPC)-rTMS. Accuracies were significantly impaired during hMT+-rTMS but not in the other two conditions (No-rTMS or PPC-rTMS), moreover, thresholds for detecting speed changes were significantly higher in the hMT+-rTMS with respect to the control TMS conditions. These findings provide stronger evidence that the activity of the hMT+ area is involved in tactile speed processing, which may be consistent with the hypothesis of a supramodal role for that cortical region in motion processing.

  5. Embodied learning of a generative neural model for biological motion perception and inference.

    Science.gov (United States)

    Schrodt, Fabian; Layher, Georg; Neumann, Heiko; Butz, Martin V

    2015-01-01

    Although an action observation network and mirror neurons for understanding the actions and intentions of others have been under deep, interdisciplinary consideration over recent years, it remains largely unknown how the brain manages to map visually perceived biological motion of others onto its own motor system. This paper shows how such a mapping may be established, even if the biologically motion is visually perceived from a new vantage point. We introduce a learning artificial neural network model and evaluate it on full body motion tracking recordings. The model implements an embodied, predictive inference approach. It first learns to correlate and segment multimodal sensory streams of own bodily motion. In doing so, it becomes able to anticipate motion progression, to complete missing modal information, and to self-generate learned motion sequences. When biological motion of another person is observed, this self-knowledge is utilized to recognize similar motion patterns and predict their progress. Due to the relative encodings, the model shows strong robustness in recognition despite observing rather large varieties of body morphology and posture dynamics. By additionally equipping the model with the capability to rotate its visual frame of reference, it is able to deduce the visual perspective onto the observed person, establishing full consistency to the embodied self-motion encodings by means of active inference. In further support of its neuro-cognitive plausibility, we also model typical bistable perceptions when crucial depth information is missing. In sum, the introduced neural model proposes a solution to the problem of how the human brain may establish correspondence between observed bodily motion and its own motor system, thus offering a mechanism that supports the development of mirror neurons.

  6. Embodied Learning of a Generative Neural Model for Biological Motion Perception and Inference

    Directory of Open Access Journals (Sweden)

    Fabian eSchrodt

    2015-07-01

    Full Text Available Although an action observation network and mirror neurons for understanding the actions and intentions of others have been under deep, interdisciplinary consideration over recent years, it remains largely unknown how the brain manages to map visually perceived biological motion of others onto its own motor system. This paper shows how such a mapping may be established, even if the biologically motion is visually perceived from a new vantage point. We introduce a learning artificial neural network model and evaluate it on full body motion tracking recordings. The model implements an embodied, predictive inference approach. It first learns to correlate and segment multimodal sensory streams of own bodily motion. In doing so, it becomes able to anticipate motion progression, to complete missing modal information, and to self-generate learned motion sequences. When biological motion of another person is observed, this self-knowledge is utilized to recognize similar motion patterns and predict their progress. Due to the relative encodings, the model shows strong robustness in recognition despite observing rather large varieties of body morphology and posture dynamics. By additionally equipping the model with the capability to rotate its visual frame of reference, it is able to deduce the visual perspective onto the observed person, establishing full consistency to the embodied self-motion encodings by means of active inference. In further support of its neuro-cognitive plausibility, we also model typical bistable perceptions when crucial depth information is missing. In sum, the introduced neural model proposes a solution to the problem of how the human brain may establish correspondence between observed bodily motion and its own motor system, thus offering a mechanism that supports the development of mirror neurons.

  7. Rocking or rolling--perception of ambiguous motion after returning from space.

    Science.gov (United States)

    Clément, Gilles; Wood, Scott J

    2014-01-01

    The central nervous system must resolve the ambiguity of inertial motion sensory cues in order to derive an accurate representation of spatial orientation. Adaptive changes during spaceflight in how the brain integrates vestibular cues with other sensory information can lead to impaired movement coordination, vertigo, spatial disorientation, and perceptual illusions after return to Earth. The purpose of this study was to compare tilt and translation motion perception in astronauts before and after returning from spaceflight. We hypothesized that these stimuli would be the most ambiguous in the low-frequency range (i.e., at about 0.3 Hz) where the linear acceleration can be interpreted either as a translation or as a tilt relative to gravity. Verbal reports were obtained in eleven astronauts tested using a motion-based tilt-translation device and a variable radius centrifuge before and after flying for two weeks on board the Space Shuttle. Consistent with previous studies, roll tilt perception was overestimated shortly after spaceflight and then recovered with 1-2 days. During dynamic linear acceleration (0.15-0.6 Hz, ±1.7 m/s2) perception of translation was also overestimated immediately after flight. Recovery to baseline was observed after 2 days for lateral translation and 8 days for fore-aft translation. These results suggest that there was a shift in the frequency dynamic of tilt-translation motion perception after adaptation to weightlessness. These results have implications for manual control during landing of a space vehicle after exposure to microgravity, as it will be the case for human asteroid and Mars missions.

  8. Rocking or rolling--perception of ambiguous motion after returning from space.

    Directory of Open Access Journals (Sweden)

    Gilles Clément

    Full Text Available The central nervous system must resolve the ambiguity of inertial motion sensory cues in order to derive an accurate representation of spatial orientation. Adaptive changes during spaceflight in how the brain integrates vestibular cues with other sensory information can lead to impaired movement coordination, vertigo, spatial disorientation, and perceptual illusions after return to Earth. The purpose of this study was to compare tilt and translation motion perception in astronauts before and after returning from spaceflight. We hypothesized that these stimuli would be the most ambiguous in the low-frequency range (i.e., at about 0.3 Hz where the linear acceleration can be interpreted either as a translation or as a tilt relative to gravity. Verbal reports were obtained in eleven astronauts tested using a motion-based tilt-translation device and a variable radius centrifuge before and after flying for two weeks on board the Space Shuttle. Consistent with previous studies, roll tilt perception was overestimated shortly after spaceflight and then recovered with 1-2 days. During dynamic linear acceleration (0.15-0.6 Hz, ±1.7 m/s2 perception of translation was also overestimated immediately after flight. Recovery to baseline was observed after 2 days for lateral translation and 8 days for fore-aft translation. These results suggest that there was a shift in the frequency dynamic of tilt-translation motion perception after adaptation to weightlessness. These results have implications for manual control during landing of a space vehicle after exposure to microgravity, as it will be the case for human asteroid and Mars missions.

  9. Local and global aspects of biological motion perception in children born at very low birth weight.

    Science.gov (United States)

    Williamson, K E; Jakobson, L S; Saunders, D R; Troje, N F

    2015-01-01

    Biological motion perception can be assessed using a variety of tasks. In the present study, 8- to 11-year-old children born prematurely at very low birth weight (body structure, and the ability to carry out higher order processes required for action recognition and person identification. Preterm children exhibited difficulties in all 4 aspects of biological motion perception. However, intercorrelations between test scores were weak in both full-term and preterm children--a finding that supports the view that these processes are relatively independent. Preterm children also displayed more autistic-like traits than full-term peers. In preterm (but not full-term) children, these traits were negatively correlated with performance in the task requiring structure-from-motion processing, r(30) = -.36, p children and suggest that a core deficit in social perception/cognition may contribute to the development of the social and behavioral difficulties even in members of this population who are functioning within the normal range intellectually. The results could inform the development of screening, diagnostic, and intervention tools.

  10. Prenatal exposure to recreational drugs affects global motion perception in preschool children.

    Science.gov (United States)

    Chakraborty, Arijit; Anstice, Nicola S; Jacobs, Robert J; LaGasse, Linda L; Lester, Barry M; Wouldes, Trecia A; Thompson, Benjamin

    2015-11-19

    Prenatal exposure to recreational drugs impairs motor and cognitive development; however it is currently unknown whether visual brain areas are affected. To address this question, we investigated the effect of prenatal drug exposure on global motion perception, a behavioural measure of processing within the dorsal extrastriate visual cortex that is thought to be particularly vulnerable to abnormal neurodevelopment. Global motion perception was measured in one hundred and forty-five 4.5-year-old children who had been exposed to different combinations of methamphetamine, alcohol, nicotine and marijuana prior to birth and 25 unexposed children. Self-reported drug use by the mothers was verified by meconium analysis. We found that global motion perception was impaired by prenatal exposure to alcohol and improved significantly by exposure to marijuana. Exposure to both drugs prenatally had no effect. Other visual functions such as habitual visual acuity and stereoacuity were not affected by drug exposure. Prenatal exposure to methamphetamine did not influence visual function. Our results demonstrate that prenatal drug exposure can influence a behavioural measure of visual development, but that the effects are dependent on the specific drugs used during pregnancy.

  11. Perceptions and use of passive intervertebral motion assessment of the spine: a survey among physiotherapists specializing in manual therapy.

    NARCIS (Netherlands)

    Trijffel, E. van; Oostendorp, R.A.B.; Lindeboom, R.; Bossuyt, P.M.; Lucas, C.

    2009-01-01

    Manual therapists commonly use passive intervertebral motion (PIVM) assessment within physical examination. Data describing the use and interpretation of this manual diagnostic procedure, as well as therapists' perception of related importance and confidence, are lacking. A survey was conducted

  12. Perceptions and use of passive intervertebral motion assessment of the spine: A survey among physiotherapists specializing in manual therapy

    NARCIS (Netherlands)

    E. van Trijffel; R.A.B. Oostendorp; R. Lindeboom; P.M.M. Bossuyt; C. Lucas

    2009-01-01

    Manual therapists commonly use passive intervertebral motion (PIVM) assessment within physical examination. Data describing the use and interpretation of this manual diagnostic procedure, as well as therapists' perception of related importance and confidence. are lacking. A survey was conducted amon

  13. Perceptions and use of passive intervertebral motion assessment of the spine: a survey among physiotherapists specializing in manual therapy.

    NARCIS (Netherlands)

    Trijffel, E. van; Oostendorp, R.A.B.; Lindeboom, R.; Bossuyt, P.M.; Lucas, C.

    2009-01-01

    Manual therapists commonly use passive intervertebral motion (PIVM) assessment within physical examination. Data describing the use and interpretation of this manual diagnostic procedure, as well as therapists' perception of related importance and confidence, are lacking. A survey was conducted amon

  14. The influence of shape-from-shading information on the perception of global motion.

    Science.gov (United States)

    Khuu, Sieu K; Khambiye, Shazaan

    2012-02-15

    The visual system is able to infer three-dimensional (3D) shape from the surface shading-gradient of objects. Using Global Dot Motion (GDM) stimuli, we investigated the influence of shape from shading on the perception of coherent local and global motion. In Experiment 1, we report that the visual system is unable to detect the local motion of dots that undergo a change in 3D shape (convex to concave shape) from frame to frame. For this condition, GDM detection thresholds were approximately four times higher than when dots do not change shape. However, when shaded dots were perceptually two-dimensional (as with bipartite and horizontally shaded dots) GDM the visual system was able to detect the global motion regardless of a change in shading direction. Finally in Experiment 3, we demonstrated that the addition of noise dots interferes with the detection of global motion only when they have same 3D shape as signal dots. GDM detection thresholds were unaffected if additional noise dots were of the opposite 3D shape. The findings of the present study demonstrate that 3D shape from shading information impacts of GDM detection, particularly, that this depth form-cue is used as a basis for independent motion analysis at both local and global levels of processing.

  15. The effect of age upon the perception of 3-D shape from motion.

    Science.gov (United States)

    Norman, J Farley; Cheeseman, Jacob R; Pyles, Jessica; Baxter, Michael W; Thomason, Kelsey E; Calloway, Autum B

    2013-12-18

    Two experiments evaluated the ability of 50 older, middle-aged, and younger adults to discriminate the 3-dimensional (3-D) shape of curved surfaces defined by optical motion. In Experiment 1, temporal correspondence was disrupted by limiting the lifetimes of the moving surface points. In order to discriminate 3-D surface shape reliably, the younger and middle-aged adults needed a surface point lifetime of approximately 4 views (in the apparent motion sequences). In contrast, the older adults needed a much longer surface point lifetime of approximately 9 views in order to reliably perform the same task. In Experiment 2, the negative effect of age upon 3-D shape discrimination from motion was replicated. In this experiment, however, the participants' abilities to discriminate grating orientation and speed were also assessed. Edden et al. (2009) have recently demonstrated that behavioral grating orientation discrimination correlates with GABA (gamma aminobutyric acid) concentration in human visual cortex. Our results demonstrate that the negative effect of age upon 3-D shape perception from motion is not caused by impairments in the ability to perceive motion per se, but does correlate significantly with grating orientation discrimination. This result suggests that the age-related decline in 3-D shape discrimination from motion is related to decline in GABA concentration in visual cortex.

  16. Cross-modal distortion of time perception: demerging the effects of observed and performed motion.

    Directory of Open Access Journals (Sweden)

    Joachim Hass

    Full Text Available Temporal information is often contained in multi-sensory stimuli, but it is currently unknown how the brain combines e.g. visual and auditory cues into a coherent percept of time. The existing studies of cross-modal time perception mainly support the "modality appropriateness hypothesis", i.e. the domination of auditory temporal cues over visual ones because of the higher precision of audition for time perception. However, these studies suffer from methodical problems and conflicting results. We introduce a novel experimental paradigm to examine cross-modal time perception by combining an auditory time perception task with a visually guided motor task, requiring participants to follow an elliptic movement on a screen with a robotic manipulandum. We find that subjective duration is distorted according to the speed of visually observed movement: The faster the visual motion, the longer the perceived duration. In contrast, the actual execution of the arm movement does not contribute to this effect, but impairs discrimination performance by dual-task interference. We also show that additional training of the motor task attenuates the interference, but does not affect the distortion of subjective duration. The study demonstrates direct influence of visual motion on auditory temporal representations, which is independent of attentional modulation. At the same time, it provides causal support for the notion that time perception and continuous motor timing rely on separate mechanisms, a proposal that was formerly supported by correlational evidence only. The results constitute a counterexample to the modality appropriateness hypothesis and are best explained by Bayesian integration of modality-specific temporal information into a centralized "temporal hub".

  17. Biological motion perception links diverse facets of theory of mind during middle childhood.

    Science.gov (United States)

    Rice, Katherine; Anderson, Laura C; Velnoskey, Kayla; Thompson, James C; Redcay, Elizabeth

    2016-06-01

    Two cornerstones of social development--social perception and theory of mind--undergo brain and behavioral changes during middle childhood, but the link between these developing domains is unclear. One theoretical perspective argues that these skills represent domain-specific areas of social development, whereas other perspectives suggest that both skills may reflect a more integrated social system. Given recent evidence from adults that these superficially different domains may be related, the current study examined the developmental relation between these social processes in 52 children aged 7 to 12 years. Controlling for age and IQ, social perception (perception of biological motion in noise) was significantly correlated with two measures of theory of mind: one in which children made mental state inferences based on photographs of the eye region of the face and another in which children made mental state inferences based on stories. Social perception, however, was not correlated with children's ability to make physical inferences from stories about people. Furthermore, the mental state inference tasks were not correlated with each other, suggesting a role for social perception in linking various facets of theory of mind.

  18. Perception of linear horizontal self-motion induced by peripheral vision /linearvection/ - Basic characteristics and visual-vestibular interactions

    Science.gov (United States)

    Berthoz, A.; Pavard, B.; Young, L. R.

    1975-01-01

    The basic characteristics of the sensation of linear horizontal motion have been studied. Objective linear motion was induced by means of a moving cart. Visually induced linear motion perception (linearvection) was obtained by projection of moving images at the periphery of the visual field. Image velocity and luminance thresholds for the appearance of linearvection have been measured and are in the range of those for image motion detection (without sensation of self motion) by the visual system. Latencies of onset are around 1 sec and short term adaptation has been shown. The dynamic range of the visual analyzer as judged by frequency analysis is lower than the vestibular analyzer. Conflicting situations in which visual cues contradict vestibular and other proprioceptive cues show, in the case of linearvection a dominance of vision which supports the idea of an essential although not independent role of vision in self motion perception.

  19. Do perceptual biases emerge early or late in visual processing? Decision-biases in motion perception.

    Science.gov (United States)

    Zamboni, Elisa; Ledgeway, Timothy; McGraw, Paul V; Schluppeck, Denis

    2016-06-29

    Visual perception is strongly influenced by contextual information. A good example is reference repulsion, where subjective reports about the direction of motion of a stimulus are significantly biased by the presence of an explicit reference. These perceptual biases could arise early, during sensory encoding, or alternatively, they may reflect decision-related processes occurring relatively late in the task sequence. To separate these two competing possibilities, we asked (human) subjects to perform a fine motion-discrimination task and then estimate the direction of motion in the presence or absence of an oriented reference line. When subjects performed the discrimination task with the reference, but subsequently estimated motion direction in its absence, direction estimates were unbiased. However, when subjects viewed the same stimuli but performed the estimation task only, with the orientation of the reference line jittered on every trial, the directions estimated by subjects were biased and yoked to the orientation of the shifted reference line. These results show that judgements made relative to a reference are subject to late, decision-related biases A model in which information about motion is integrated with that of an explicit reference cue, resulting in a late, decision-related re-weighting of the sensory representation, can account for these results.

  20. Effects of dynamic luminance modulation on visually induced self-motion perception: observers' perception of illumination is important in perceiving self-motion.

    Science.gov (United States)

    Nakamura, Shinji; Seno, Takeharu; Ito, Hiroyuki; Sunaga, Shoji

    2013-01-01

    Coherent luminance modulation of visual objects affects visually induced perception of self-motion (vection). The perceptual mechanism underlying the effects of dynamic luminance modulation were investigated with a visual stimulus simulating an external environment illuminated by a moving spotlight (the normal spotlight condition) or an inverted luminance version of it (the inverted luminance condition). Two psychophysical experiments indicated that vection was generally weakened in the inverted luminance condition. The results cannot be fully explained by the undesirable differences of luminosity within the experimental environment, and suggest that the contrast polarity of the visual stimulus has a significant impact on vection. Furthermore, the results show that the dynamic luminance variations weaken vection in the normal spotlight condition in which the observers perceived illumination modulations. In contrast, in the inverted luminance condition, in which the observers cannot perceive the illumination manipulation, the dynamic luminance variations may not impair vection, and may even be expected to strengthen vection, even though they shared similar global and systematic luminance variation with the normal spotlight condition. These experiments suggest that the observer's perception of illumination is a key factor in considering the effects of dynamic luminance modulation of the visual stimulus.

  1. Color improves speed of processing but not perception in a motion illusion

    Directory of Open Access Journals (Sweden)

    Carolyn J Perry

    2012-03-01

    Full Text Available When two superimposed surfaces of dots move in different directions, the perceived directions are shifted away from each other. This perceptual illusion has been termed direction repulsion and is thought to be due to mutual inhibition between the representations of the two directions. It has further been shown that a speed difference between the two surfaces attenuates direction repulsion. As speed and direction are both necessary components of representing motion, the reduction in direction repulsion can be attributed to the additional motion information strengthening the representations of the two directions and thus reducing the mutual inhibition. We tested whether bottom-up attention and top-down task demands, in the form of color differences between the two surfaces, would also enhance motion processing, reducing direction repulsion. We found that the addition of color differences did not improve direction discrimination and reduce direction repulsion. However, we did find that adding a color difference improved performance on the task. We hypothesized that the performance differences were due to the limited presentation time of the stimuli. We tested this in a follow-up experiment where we varied the time of presentation to determine the duration needed to successfully perform the task with and without the color difference. As we expected, the addition of color reduced the amount of time needed to process and encode both directions of motion. Thus we find a dissociation between the effects of attention on the speed of processing and conscious perception. We propose 4 potential mechanisms wherein color speeds figure-ground segmentation of an object, attentional switching between objects, direction discrimination and/or the accumulation of motion information for decision-making, without affecting conscious perception. Potential neural bases are also explored.

  2. Integration of 3D structure from disparity into biological motion perception independent of depth awareness.

    Science.gov (United States)

    Wang, Ying; Jiang, Yi

    2014-01-01

    Images projected onto the retinas of our two eyes come from slightly different directions in the real world, constituting binocular disparity that serves as an important source for depth perception - the ability to see the world in three dimensions. It remains unclear whether the integration of disparity cues into visual perception depends on the conscious representation of stereoscopic depth. Here we report evidence that, even without inducing discernible perceptual representations, the disparity-defined depth information could still modulate the visual processing of 3D objects in depth-irrelevant aspects. Specifically, observers who could not discriminate disparity-defined in-depth facing orientations of biological motions (i.e., approaching vs. receding) due to an excessive perceptual bias nevertheless exhibited a robust perceptual asymmetry in response to the indistinguishable facing orientations, similar to those who could consciously discriminate such 3D information. These results clearly demonstrate that the visual processing of biological motion engages the disparity cues independent of observers' depth awareness. The extraction and utilization of binocular depth signals thus can be dissociable from the conscious representation of 3D structure in high-level visual perception.

  3. The Content of Imagined Sounds Changes Visual Motion Perception in the Cross-Bounce Illusion

    Science.gov (United States)

    Berger, Christopher C.; Ehrsson, H. Henrik

    2017-01-01

    Can what we imagine hearing change what we see? Whether imagined sensory stimuli are integrated with external sensory stimuli to shape our perception of the world has only recently begun to come under scrutiny. Here, we made use of the cross-bounce illusion in which an auditory stimulus presented at the moment two passing objects meet promotes the perception that the objects bounce off rather than cross by one another to examine whether the content of imagined sound changes visual motion perception in a manner that is consistent with multisensory integration. The results from this study revealed that auditory imagery of a sound with acoustic properties typical of a collision (i.e., damped sound) promoted the bounce-percept, but auditory imagery of the same sound played backwards (i.e., ramped sound) did not. Moreover, the vividness of the participants’ auditory imagery predicted the strength of this imagery-induced illusion. In a separate experiment, we ruled out the possibility that changes in attention (i.e., sensitivity index d′) or response bias (response bias index c) were sufficient to explain this effect. Together, these findings suggest that this imagery-induced multisensory illusion reflects the successful integration of real and imagined cross-modal sensory stimuli, and more generally, that what we imagine hearing can change what we see. PMID:28071707

  4. S1-1: Individual Differences in the Perception of Biological Motion

    Directory of Open Access Journals (Sweden)

    Ian Thornton

    2012-10-01

    Full Text Available Our ability to accurately perceive the actions of others based on reduced visual cues has been well documented. Previous work has suggested that this ability is probably made possible by separable mechanisms that can operate in either a passive, bottom-up fashion or an active, top-down fashion (Thornton, Rensink, & Shiffrar, 2002 Perception 31 837–853. One line of evidence for exploring the contribution of top-down mechanisms is to consider the extent to which individual differences in more general cognitive abilities, such as attention and working memory, predict performance on biological motion tasks. In this talk, I will begin by reviewing previous work that has looked at biological motion processing in clinical settings and as a function of domain-specific expertise. I will then introduce a new task that we are using in my lab to explore individual variation in action matching as a function of independently assessed attentional control and working memory capacity.

  5. Age differences in visual-auditory self-motion perception during a simulated driving task

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    Robert eRamkhalawansingh

    2016-04-01

    Full Text Available Recent evidence suggests that visual-auditory cue integration may change as a function of age such that integration is heightened among older adults. Our goal was to determine whether these changes in multisensory integration are also observed in the context of self-motion perception under realistic task constraints. Thus, we developed a simulated driving paradigm in which we provided older and younger adults with visual motion cues (i.e. optic flow and systematically manipulated the presence or absence of congruent auditory cues to self-motion (i.e. engine, tire, and wind sounds. Results demonstrated that the presence or absence of congruent auditory input had different effects on older and younger adults. Both age groups demonstrated a reduction in speed variability when auditory cues were present compared to when they were absent, but older adults demonstrated a proportionally greater reduction in speed variability under combined sensory conditions. These results are consistent with evidence indicating that multisensory integration is heightened in older adults. Importantly, this study is the first to provide evidence to suggest that age differences in multisensory integration may generalize from simple stimulus detection tasks to the integration of the more complex and dynamic visual and auditory cues that are experienced during self-motion.

  6. Action induction due to visual perception of linear motion in depth.

    Science.gov (United States)

    Classen, Claudia; Kibele, Armin

    2017-01-01

    Visually perceived motion can affect observers' motor control in such a way that an intended action can be activated automatically when it contains similar spatial features. So far, effects have been mostly demonstrated with simple displays where objects were moving in a two-dimensional plane. However, almost all actions we perform and visually perceive in everyday life are much more complex and take place in three-dimensional space. The purpose of this study was to examine action inductions due to visual perception of motion in depth. Therefore, we conducted two Simon experiments where subjects were presented with video displays of a sphere (simple displays, experiment 1) and a real person (complex displays, experiment 2) moving in depth. In both experiments, motion direction towards and away from the observer served as task irrelevant information whereas a color change in the video served as relevant information to choose the correct response (close or far positioned response key). The results show that subjects reacted faster when motion direction of the dynamic stimulus was corresponding to the spatial position of the demanded response. In conclusion, this direction-based Simon effect is modulated by spatial position information, higher sensitivity of our visual system for looming objects, and a high salience of objects being on a collision course.

  7. Detecting Biological Motion for Human–Robot Interaction: A Link between Perception and Action

    Directory of Open Access Journals (Sweden)

    Alessia Vignolo

    2017-06-01

    Full Text Available One of the fundamental skills supporting safe and comfortable interaction between humans is their capability to understand intuitively each other’s actions and intentions. At the basis of this ability is a special-purpose visual processing that human brain has developed to comprehend human motion. Among the first “building blocks” enabling the bootstrapping of such visual processing is the ability to detect movements performed by biological agents in the scene, a skill mastered by human babies in the first days of their life. In this paper, we present a computational model based on the assumption that such visual ability must be based on local low-level visual motion features, which are independent of shape, such as the configuration of the body and perspective. Moreover, we implement it on the humanoid robot iCub, embedding it into a software architecture that leverages the regularities of biological motion also to control robot attention and oculomotor behaviors. In essence, we put forth a model in which the regularities of biological motion link perception and action enabling a robotic agent to follow a human-inspired sensory-motor behavior. We posit that this choice facilitates mutual understanding and goal prediction during collaboration, increasing the pleasantness and safety of the interaction.

  8. Perception of Self-Motion and Regulation of Walking Speed in Young-Old Adults.

    Science.gov (United States)

    Lalonde-Parsi, Marie-Jasmine; Lamontagne, Anouk

    2015-07-01

    Whether a reduced perception of self-motion contributes to poor walking speed adaptations in older adults is unknown. In this study, speed discrimination thresholds (perceptual task) and walking speed adaptations (walking task) were compared between young (19-27 years) and young-old individuals (63-74 years), and the relationship between the performance on the two tasks was examined. Participants were evaluated while viewing a virtual corridor in a helmet-mounted display. Speed discrimination thresholds were determined using a staircase procedure. Walking speed modulation was assessed on a self-paced treadmill while exposed to different self-motion speeds ranging from 0.25 to 2 times the participants' comfortable speed. For each speed, participants were instructed to match the self-motion speed described by the moving corridor. On the walking task, participants displayed smaller walking speed errors at comfortable walking speeds compared with slower of faster speeds. The young-old adults presented larger speed discrimination thresholds (perceptual experiment) and larger walking speed errors (walking experiment) compared with young adults. Larger walking speed errors were associated with higher discrimination thresholds. The enhanced performance on the walking task at comfortable speed suggests that intersensory calibration processes are influenced by experience, hence optimized for frequently encountered conditions. The altered performance of the young-old adults on the perceptual and walking tasks, as well as the relationship observed between the two tasks, suggest that a poor perception of visual motion information may contribute to the poor walking speed adaptations that arise with aging.

  9. Tactile input and empathy ability modulate the perception of ambiguous biological motion

    Directory of Open Access Journals (Sweden)

    Hörmetjan eYiltiz

    2015-02-01

    Full Text Available Evidence has shown that task-irrelevant auditory cues can bias perceptual decisions regarding directional information associated with biological motion, as indicated in perceptual tasks using point-light walkers (PLWs (Brooks et al., 2007. In the current study, we extended the investigation of cross-modal influences to the tactile domain by asking how tactile input resolves perceptual ambiguity in visual apparent motion, and how empathy ability plays a role in this cross-modal interaction. In Experiment 1, we simulated the tactile feedback on the observers’ fingertips when the (upright or inverted PLWs (comprised of either all red or all green dots were walking (leftwards or rightwards. The temporal periods between tactile events and critical visual events (the PLW’s feet hitting the ground were manipulated so that the tap could lead, synchronize, or lag with the visual foot-hitting-ground event. We found that the temporal structures between tactile (feedback and visual (hitting events systematically modulate the directional perception for upright PLWs, making either leftwards or rightwards more dominant. However, this temporal modulation effect was absent for inverted PLWs. In Experiment 2, we examined how empathy ability modulates cross-modal capture. Instead of generating tactile feedback on participant’s fingertips, we gave taps on their ankles and presented the PLWs with motion directions of approaching (facing towards observer/receding (facing away from observer to resemble normal walking postures. With the same temporal structure, we found that individuals with higher empathic ability were more subject to perceptual bias in the presence of tactile feedback. Taken together, our findings showed that task-irrelevant tactile input can resolve the otherwise ambiguous perception of the directional information of biological motion, whereas cross-modal modulation was mediated by higher level social-cognitive factors, including empathic

  10. Tactile input and empathy modulate the perception of ambiguous biological motion.

    Science.gov (United States)

    Yiltiz, Hörmetjan; Chen, Lihan

    2015-01-01

    Evidence has shown that task-irrelevant auditory cues can bias perceptual decisions regarding directional information associated with biological motion, as indicated in perceptual tasks using point-light walkers (PLWs) (Brooks et al., 2007). In the current study, we extended the investigation of cross-modal influences to the tactile domain by asking how tactile input resolves perceptual ambiguity in visual apparent motion, and how empathy plays a role in this cross-modal interaction. In Experiment 1, we simulated the tactile feedback on the observers' fingertips when the (upright or inverted) PLWs (comprised of either all red or all green dots) were walking (leftwards or rightwards). The temporal periods between tactile events and critical visual events (the PLW's feet hitting the ground) were manipulated so that the tap could lead, synchronize, or lag the visual foot-hitting-ground event. We found that the temporal structures between tactile (feedback) and visual (hitting) events systematically biases the directional perception for upright PLWs, making either leftwards or rightwards more dominant. However, this effect was absent for inverted PLWs. In Experiment 2, we examined how empathy modulates cross-modal capture. Instead of giving tactile feedback on participants' fingertips, we gave taps on their ankles and presented the PLWs with motion directions of approaching (facing toward observer)/receding (facing away from observer) to resemble normal walking postures. With the same temporal structure, we found that individuals with higher empathy were more subject to perceptual bias in the presence of tactile feedback. Taken together, our findings showed that task-irrelevant tactile input can resolve the otherwise ambiguous perception of the direction of biological motion, and this cross-modal bias was mediated by higher level social-cognitive factors, including empathy.

  11. Frame rate of motion picture and its influence on speech perception

    Science.gov (United States)

    Nakazono, Kaoru

    1996-03-01

    The preservation of QoS for multimedia traffic through a data network is a difficult problem. We focus our attention on video frame rate and study its influence on speech perception. When sound and picture are discrepant (e.g., acoustic `ba' combined with visual `ga'), subjects perceive a different sound (such as `da'). This phenomenon is known as the McGurk effect. In this paper, the influence of degraded video frame rate on speech perception was studied. It was shown that when frame rate decreases, correct hearing is improved for discrepant stimuli and is degraded for congruent (voice and picture are the same) stimuli. Furthermore, we studied the case where lip closure was always captured by the synchronization of sampling time and lip position. In this case, frame rate has little effect on mishearing for congruent stimuli. For discrepant stimuli, mishearing is decreased with degraded frame rate. These results indicate that stiff motion of lips resulting from low frame rate cannot give enough labial information for speech perception. In addition, the effect of delaying the picture to correct for low frame rate was studied. The results, however, were not as definitive as expected because of compound effects related to the synchronization of sound and picture.

  12. The effect of oxytocin on biological motion perception in dogs (Canis familiaris).

    Science.gov (United States)

    Kovács, Krisztina; Kis, Anna; Kanizsár, Orsolya; Hernádi, Anna; Gácsi, Márta; Topál, József

    2016-05-01

    Recent studies have shown that the neuropeptide oxytocin is involved in the regulation of several complex human social behaviours. There is, however, little research on the effect of oxytocin on basic mechanisms underlying human sociality, such as the perception of biological motion. In the present study, we investigated the effect of oxytocin on biological motion perception in dogs (Canis familiaris), a species adapted to the human social environment and thus widely used to model many aspects of human social behaviour. In a within-subjects design, dogs (N = 39), after having received either oxytocin or placebo treatment, were presented with 2D projection of a moving point-light human figure and the inverted and scrambled version of the same movie. Heart rate (HR) and heart rate variability (HRV) were measured as physiological responses, and behavioural response was evaluated by observing dogs' looking time. Subjects were also rated on the personality traits of Neuroticism and Agreeableness by their owners. As expected, placebo-pretreated (control) dogs showed a spontaneous preference for the biological motion pattern; however, there was no such preference after oxytocin pretreatment. Furthermore, following the oxytocin pretreatment female subjects looked more at the moving point-light figure than males. The individual variations along the dimensions of Agreeableness and Neuroticism also modulated dogs' behaviour. Furthermore, HR and HRV measures were affected by oxytocin treatment and in turn played a role in subjects' looking behaviour. We discuss how these findings contribute to our understanding of the neurohormonal regulatory mechanisms of human (and non-human) social skills.

  13. Brain asymmetry modulates perception of biological motion in newborn chicks (Gallus gallus).

    Science.gov (United States)

    Rugani, Rosa; Rosa Salva, Orsola; Regolin, Lucia; Vallortigara, Giorgio

    2015-09-01

    Few light-points on the joints of a moving animal give the impression of biological motion (BM). Day-old chicks prefer BM to non-BM, suggesting a conserved predisposition to attend to moving animals. In humans and other mammals a network of regions, primarily in the right hemisphere, provides the neural substrate for BM perception. However, this has not been investigated in avians. In birds the information from each eye is mainly feeding to the contralateral hemisphere. To study brain asymmetry, we recorded the eye spontaneously used by chicks to inspect a BM stimulus. We also investigated the effect of lateralization following light exposure of the embryos. In Experiment 1, highly lateralized chicks aligned with the apparent direction of motion only when they were exposed to a BM-stimulus moving rightward first, monitoring it with the left-eye-system. In Experiment 2 weakly lateralized chicks did not show any behavioral asymmetry. Moreover, they counter aligned with the apparent direction of motion. Brain lateralization affects chicks behavior while processing and approaching a BM stimulus. Highly lateralized chicks aligned their body with the apparent direction of the BM, a behavior akin to a following response, monitoring the stimulus preferentially with their left eye. This suggests a right hemisphere dominance in BM processing. Weakly lateralized chicks counter-aligned with the apparent direction of the BM, facing it during interaction, and monitored it equally with both eyes. Environmental factors (light stimulation) seem to affect the development of lateralization, and consequently social behavior.

  14. Role of orientation reference selection in motion sickness

    Science.gov (United States)

    Peterka, Robert J.; Black, F. Owen

    1992-01-01

    The overall objective of this proposal is to understand the relationship between human orientation control and motion sickness susceptibility. Three areas related to orientation control will be investigated. These three areas are (1) reflexes associated with the control of eye movements and posture, (2) the perception of body rotation and position with respect to gravity, and (3) the strategies used to resolve sensory conflict situations which arise when different sensory systems provide orientation cues which are not consistent with one another or with previous experience. Of particular interest is the possibility that a subject may be able to ignore an inaccurate sensory modality in favor of one or more other sensory modalities which do provide accurate orientation reference information. We refer to this process as sensory selection. This proposal will attempt to quantify subjects' sensory selection abilities and determine if this ability confers some immunity to the development of motion sickness symptoms. Measurements of reflexes, motion perception, sensory selection abilities, and motion sickness susceptibility will concentrate on pitch and roll motions since these seem most relevant to the space motion sickness problem. Vestibulo-ocular (VOR) and oculomotor reflexes will be measured using a unique two-axis rotation device developed in our laboratory over the last seven years. Posture control reflexes will be measured using a movable posture platform capable of independently altering proprioceptive and visual orientation cues. Motion perception will be quantified using closed loop feedback technique developed by Zacharias and Young (Exp Brain Res, 1981). This technique requires a subject to null out motions induced by the experimenter while being exposed to various confounding sensory orientation cues. A subject's sensory selection abilities will be measured by the magnitude and timing of his reactions to changes in sensory environments. Motion sickness

  15. Motion

    CERN Document Server

    Graybill, George

    2007-01-01

    Take the mystery out of motion. Our resource gives you everything you need to teach young scientists about motion. Students will learn about linear, accelerating, rotating and oscillating motion, and how these relate to everyday life - and even the solar system. Measuring and graphing motion is easy, and the concepts of speed, velocity and acceleration are clearly explained. Reading passages, comprehension questions, color mini posters and lots of hands-on activities all help teach and reinforce key concepts. Vocabulary and language are simplified in our resource to make them accessible to str

  16. Visual area V5/hMT+ contributes to perception of tactile motion direction: a TMS study.

    Science.gov (United States)

    Amemiya, Tomohiro; Beck, Brianna; Walsh, Vincent; Gomi, Hiroaki; Haggard, Patrick

    2017-01-20

    Human imaging studies have reported activations associated with tactile motion perception in visual motion area V5/hMT+, primary somatosensory cortex (SI) and posterior parietal cortex (PPC; Brodmann areas 7/40). However, such studies cannot establish whether these areas are causally involved in tactile motion perception. We delivered double-pulse transcranial magnetic stimulation (TMS) while moving a single tactile point across the fingertip, and used signal detection theory to quantify perceptual sensitivity to motion direction. TMS over both SI and V5/hMT+, but not the PPC site, significantly reduced tactile direction discrimination. Our results show that V5/hMT+ plays a causal role in tactile direction processing, and strengthen the case for V5/hMT+ serving multimodal motion perception. Further, our findings are consistent with a serial model of cortical tactile processing, in which higher-order perceptual processing depends upon information received from SI. By contrast, our results do not provide clear evidence that the PPC site we targeted (Brodmann areas 7/40) contributes to tactile direction perception.

  17. Dynamic cortical activity during the perception of three-dimensional object shape from two-dimensional random-dot motion.

    Science.gov (United States)

    Iwaki, Sunao; Bonmassar, Giorgio; Belliveau, John W

    2013-09-01

    Recent neuroimaging studies implicate that both the dorsal and ventral visual pathways, as well as the middle temporal (MT) areas which are critical for the perception of visual motion, are involved in the perception of three-dimensional (3D) structure from two-dimensional (2D) motion (3D-SFM). However, the neural dynamics underlying the reconstruction of a 3D object from 2D optic flow is not known. Here we combined magnetoencephalography (MEG) and functional MRI (fMRI) measurements to investigate the spatiotemporal brain dynamics during 3D-SFM. We manipulated parametrically the coherence of randomly moving groups of dots to create different levels of 3D perception and to study the associated changes in brain activity. At different latencies, the posterior infero-temporal (pIT), the parieto-occipital (PO), and the intraparietal (IP) regions showed increased neural activity during highly coherent motion conditions in which subjects perceived a robust 3D object. Causality analysis between these regions indicated significant causal influence from IP to pIT and from pIT to PO only in conditions where subjects perceived a robust 3D object. Current results suggest that the perception of a 3D object from 2D motion includes integration of global motion and 3D mental image processing, as well as object recognition that are accomplished by interactions between the dorsal and ventral visual pathways.

  18. Perception and discrimination of movement and biological motion patterns in fish.

    Science.gov (United States)

    Schluessel, V; Kortekamp, N; Cortes, J A Ortiz; Klein, A; Bleckmann, H

    2015-09-01

    Vision is of primary importance for many fish species, as is the recognition of movement. With the exception of one study, assessing the influence of conspecific movement on shoaling behaviour, the perception of biological motion in fish had not been studied in a cognitive context. The aim of the present study was therefore to assess the discrimination abilities of two teleost species in regard to simple and complex movement patterns of dots and objects, including biological motion patterns using point and point-light displays (PDs and PLDs). In two-alternative forced-choice experiments, in which choosing the designated positive stimulus was food-reinforced, fish were first tested in their ability to distinguish the video of a stationary black dot on a light background from the video of a moving black dot presented at different frequencies and amplitudes. While all fish succeeded in learning the task, performance declined with decreases in either or both parameters. In subsequent tests, cichlids and damselfish distinguished successfully between the videos of two dots moving at different speeds and amplitudes, between two moving dot patterns (sinus vs. expiring sinus) and between animated videos of two moving organisms (trout vs. eel). Transfer tests following the training of the latter showed that fish were unable to identify the positive stimulus (trout) by means of its PD alone, thereby indicating that the ability of humans to spontaneously recognize an organism based on its biological motion may not be present in fish. All participating individuals successfully discriminated between two PDs and two PLDs after a short period of training, indicating that biological motions presented in form of PLDs are perceived and can be distinguished. Results were the same for the presentation of dark dots on a light background and light dots on a dark background.

  19. Morphing technique reveals intact perception of object motion and disturbed perception of emotional expressions by low-functioning adolescents with Autism Spectrum Disorder.

    Science.gov (United States)

    Han, Bora; Tijus, Charles; Le Barillier, Florence; Nadel, Jacqueline

    2015-12-01

    A morphing procedure has been designed to compare directly the perception of emotional expressions and of moving objects. Morphing tasks were presented to 12 low-functioning teenagers with Autism Spectrum Disorder (LF ASD) compared to 12 developmental age-matched typical children and a group presenting ceiling performance. In a first study, when presented with morphed stimuli of objects and emotional faces, LF ASD showed an intact perception of object change of state together with an impaired perception of emotional facial change of state. In a second study, an eye-tracker recorded visual exploration of morphed emotional stimuli displayed by a human face and a robotic set-up. Facing the morphed robotic stimuli, LF ASD displayed equal duration of fixations toward emotional regions and toward mechanical sources of motion, while the typical groups tracked the emotional regions only. Altogether the findings of the two studies suggest that individuals with ASD process motion rather than emotional signals when facing facial expressions.

  20. P3-18: Examining Neural Representation of Bi-Directional Motions with Directional Performance in Transparency Perception

    Directory of Open Access Journals (Sweden)

    Osamu Watanabe

    2012-10-01

    Full Text Available When we look at two overlapping random-dot patterns moving toward different directions, we perceive two global motions simultaneously in the same region of a visual field; this perception is known as motion transparency. After Braddick and his colleagues' work on comparing perceptual performances in transparent and single motion stimuli (2002 Vision Research 42 1237–1248, it has been considered as one of the promising cues for revealing how superimposed motions are represented in the brain. The perceptual performance would reflect encoding property of overlapping motions, and it enables us to examine the encoding models quantitatively. In the present study, we carried out psychophysical experiments to measure the directional performances in motion transparency and examined if established models of MT responses, a simple weighted sum and a normalization model, were consistent with the performances obtained experimentally. In psychophysical experiments, we measured precisions, or standard deviations, of perceived angles between two overlapping motion directions. The result showed that the perceptual performance was getting worse as a directional difference between two motions increased, while the precision was improved when dot densities of two motions differed considerably. In computational analyses, we compared the experimental results with the encoding properties of MT population models by using Fisher information that told us the lower bounds of the variances of decoded directions. The analyses showed that there was a qualitative difference between the model properties and experimentally obtained performances. Our results suggest that conventional models of MT responses cannot interpret perceptual property of motion transparency.

  1. NATO Symposium entitled "Symposium on the Study of Motion Perception : Recent Developments and Applications"

    CERN Document Server

    Wagenaar, Willem; Leibowitz, Herschel

    1982-01-01

    From August 24-29, 1980 the international "Symposium on the Study of Motion Perception; Recent Developments and Applications", sponsored by NATO and organized by the editors of this book, was held in Veldhoven, the Netherlands. The meeting was attended by about eighty scholars, including psychologists, neurologists, physicists and other scientists, from fourteen different countries. During the symposium some fifty research papers were presented and a series of tutorial review papers were read and discussed. The research presentations have been published in a special issue of the international journal of psychonomics "Acta Psychologica" (Vol. 48, 1981). The present book is a compilation of the tutorial papers. The tutorials were arranged around early versions of the chapters now appearing in this book. The long discussions at the Veldhoven tutorial sessions resulted in extensive revisions of the texts prior to this publication. Unfortunately this led to a delay in publication, but we feel that this was justifi...

  2. Abnormal Size-Dependent Modulation of Motion Perception in Children with Autism Spectrum Disorder (ASD).

    Science.gov (United States)

    Sysoeva, Olga V; Galuta, Ilia A; Davletshina, Maria S; Orekhova, Elena V; Stroganova, Tatiana A

    2017-01-01

    Excitation/Inhibition (E/I) imbalance in neural networks is now considered among the core neural underpinnings of autism psychopathology. In motion perception at least two phenomena critically depend on E/I balance in visual cortex: spatial suppression (SS), and spatial facilitation (SF) corresponding to impoverished or improved motion perception with increasing stimuli size, respectively. While SS is dominant at high contrast, SF is evident for low contrast stimuli, due to the prevalence of inhibitory contextual modulations in the former, and excitatory ones in the latter case. Only one previous study (Foss-Feig et al., 2013) investigated SS and SF in Autism Spectrum Disorder (ASD). Our study aimed to replicate previous findings, and to explore the putative contribution of deficient inhibitory influences into an enhanced SF index in ASD-a cornerstone for interpretation proposed by Foss-Feig et al. (2013). The SS and SF were examined in 40 boys with ASD, broad spectrum of intellectual abilities (63 ASD. The presence of abnormally enhanced SF in children with ASD was the only consistent finding between our study and that of Foss-Feig et al. While the SS and SF indexes were strongly interrelated in TD participants, this correlation was absent in their peers with ASD. In addition, the SF index but not the SS index correlated with the severity of autism and the poor registration abilities. The pattern of results is partially consistent with the idea of hypofunctional inhibitory transmission in visual areas in ASD. Nonetheless, the absence of correlation between SF and SS indexes paired with a strong direct link between abnormally enhanced SF and autism symptoms in our ASD sample emphasizes the role of the enhanced excitatory influences by themselves in the observed abnormalities in low-level visual phenomena found in ASD.

  3. The use of a tactile interface to convey position and motion perceptions

    Science.gov (United States)

    Rupert, A. H.; Guedry, F. E.; Reschke, M. F.

    1994-01-01

    Under normal terrestrial conditions, perception of position and motion is determined by central nervous system integration of concordant and redundant information from multiple sensory channels (somatosensory, vestibular, visual), which collectively yield vertical perceptions. In the acceleration environment experienced by the pilots, the somatosensory and vestibular sensors frequently present false information concerning the direction of gravity. When presented with conflicting sensory information, it is normal for pilots to experience episodes of disorientation. We have developed a tactile interface that obtains vertical roll and pitch information from a gyro-stabilized attitude indicator and maps this information in a one-to-one correspondence onto the torso of the body using a matrix of vibrotactors. This enables the pilot to continuously maintain an awareness of aircraft attitude without reference to visual cues, utilizing a sensory channel that normally operates at the subconscious level. Although initially developed to improve pilot spatial awareness, this device has obvious applications to 1) simulation and training, 2) nonvisual tracking of targets, which can reduce the need for pilots to make head movements in the high-G environment of aerial combat, and 3) orientation in environments with minimal somatosensory cues (e.g., underwater) or gravitational cues (e.g., space).

  4. Binocular Perception of 2D Lateral Motion and Guidance of Coordinated Motor Behavior.

    Science.gov (United States)

    Fath, Aaron J; Snapp-Childs, Winona; Kountouriotis, Georgios K; Bingham, Geoffrey P

    2016-04-01

    Zannoli, Cass, Alais, and Mamassian (2012) found greater audiovisual lag between a tone and disparity-defined stimuli moving laterally (90-170 ms) than for disparity-defined stimuli moving in depth or luminance-defined stimuli moving laterally or in depth (50-60 ms). We tested if this increased lag presents an impediment to visually guided coordination with laterally moving objects. Participants used a joystick to move a virtual object in several constant relative phases with a laterally oscillating stimulus. Both the participant-controlled object and the target object were presented using a disparity-defined display that yielded information through changes in disparity over time (CDOT) or using a luminance-defined display that additionally provided information through monocular motion and interocular velocity differences (IOVD). Performance was comparable for both disparity-defined and luminance-defined displays in all relative phases. This suggests that, despite lag, perception of lateral motion through CDOT is generally sufficient to guide coordinated motor behavior.

  5. Enhanced perceptions of control and predictability reduce motion-induced nausea and gastric dysrhythmia.

    Science.gov (United States)

    Levine, Max E; Stern, Robert M; Koch, Kenneth L

    2014-08-01

    Nausea is a debilitating condition that is typically accompanied by gastric dysrhythmia. The enhancement of perceived control and predictability has generally been found to attenuate the physiological stress response. The aim of the present study was to test the effect of these psychosocial variables in the context of nausea, motion sickness, and gastric dysrhythmia. A 2x2, independent-groups, factorial design was employed in which perceived control and predictability were each provided at high or low levels to 80 participants before exposure to a rotating optokinetic drum. Ratings of nausea were obtained throughout a 6-min baseline period and a 16-min drum rotation period. Noninvasive recordings of the electrical activity of the stomach called electrogastrograms were also obtained throughout the study. Nausea scores were significantly lower among participants with high control than among those with low control, and were significantly lower among participants with high predictability than among those with low predictability. Estimates of gastric dysrhythmia obtained from the EGG during drum rotation were significantly lower among participants with high predictability than among those with low predictability. A significant interaction effect of control and predictability on gastric dysrhythmia was also observed, such that high control was only effective for arresting the development of gastric dysrhythmia when high predictability was also available. Stronger perceptions of control and predictability may temper the development of nausea and gastric dysrhythmia during exposure to provocative motion. Psychosocial interventions in a variety of nausea contexts may represent an alternative means of symptom control.

  6. Dopamine Activation Preserves Visual Motion Perception Despite Noise Interference of Human V5/MT

    Science.gov (United States)

    Yousif, Nada; Fu, Richard Z.; Abou-El-Ela Bourquin, Bilal; Bhrugubanda, Vamsee; Schultz, Simon R.

    2016-01-01

    When processing sensory signals, the brain must account for noise, both noise in the stimulus and that arising from within its own neuronal circuitry. Dopamine receptor activation is known to enhance both visual cortical signal-to-noise-ratio (SNR) and visual perceptual performance; however, it is unknown whether these two dopamine-mediated phenomena are linked. To assess this, we used single-pulse transcranial magnetic stimulation (TMS) applied to visual cortical area V5/MT to reduce the SNR focally and thus disrupt visual motion discrimination performance to visual targets located in the same retinotopic space. The hypothesis that dopamine receptor activation enhances perceptual performance by improving cortical SNR predicts that dopamine activation should antagonize TMS disruption of visual perception. We assessed this hypothesis via a double-blinded, placebo-controlled study with the dopamine receptor agonists cabergoline (a D2 agonist) and pergolide (a D1/D2 agonist) administered in separate sessions (separated by 2 weeks) in 12 healthy volunteers in a William's balance-order design. TMS degraded visual motion perception when the evoked phosphene and the visual stimulus overlapped in time and space in the placebo and cabergoline conditions, but not in the pergolide condition. This suggests that dopamine D1 or combined D1 and D2 receptor activation enhances cortical SNR to boost perceptual performance. That local visual cortical excitability was unchanged across drug conditions suggests the involvement of long-range intracortical interactions in this D1 effect. Because increased internal noise (and thus lower SNR) can impair visual perceptual learning, improving visual cortical SNR via D1/D2 agonist therapy may be useful in boosting rehabilitation programs involving visual perceptual training. SIGNIFICANCE STATEMENT In this study, we address the issue of whether dopamine activation improves visual perception despite increasing sensory noise in the visual cortex

  7. Ventral and dorsal streams processing visual motion perception (FDG-PET study

    Directory of Open Access Journals (Sweden)

    Becker-Bense Sandra

    2012-07-01

    Full Text Available Abstract Background Earlier functional imaging studies on visually induced self-motion perception (vection disclosed a bilateral network of activations within primary and secondary visual cortex areas which was combined with signal decreases, i.e., deactivations, in multisensory vestibular cortex areas. This finding led to the concept of a reciprocal inhibitory interaction between the visual and vestibular systems. In order to define areas involved in special aspects of self-motion perception such as intensity and duration of the perceived circular vection (CV or the amount of head tilt, correlation analyses of the regional cerebral glucose metabolism, rCGM (measured by fluorodeoxyglucose positron-emission tomography, FDG-PET and these perceptual covariates were performed in 14 healthy volunteers. For analyses of the visual-vestibular interaction, the CV data were compared to a random dot motion stimulation condition (not inducing vection and a control group at rest (no stimulation at all. Results Group subtraction analyses showed that the visual-vestibular interaction was modified during CV, i.e., the activations within the cerebellar vermis and parieto-occipital areas were enhanced. The correlation analysis between the rCGM and the intensity of visually induced vection, experienced as body tilt, showed a relationship for areas of the multisensory vestibular cortical network (inferior parietal lobule bilaterally, anterior cingulate gyrus, the medial parieto-occipital cortex, the frontal eye fields and the cerebellar vermis. The “earlier” multisensory vestibular areas like the parieto-insular vestibular cortex and the superior temporal gyrus did not appear in the latter analysis. The duration of perceived vection after stimulus stop was positively correlated with rCGM in medial temporal lobe areas bilaterally, which included the (para-hippocampus, known to be involved in various aspects of memory processing. The amount of head tilt was found

  8. Integration of monocular motion signals and the analysis of interocular velocity differences for the perception of motion-in-depth.

    Science.gov (United States)

    Shioiri, Satoshi; Kakehi, Daisuke; Tashiro, Tomoyoshi; Yaguchi, Hirohisa

    2009-12-09

    We investigated how the mechanism for perceiving motion-in-depth based on interocular velocity differences (IOVDs) integrates signals from the motion spatial frequency (SF) channels. We focused on the question whether this integration is implemented before or after the comparison of the velocity signals from the two eyes. We measured spatial frequency selectivity of the MAE of motion in depth (3D MAE). The 3D MAE showed little spatial frequency selectivity, whereas the 2D lateral MAE showed clear spatial frequency selectivity in the same condition. This indicates that the outputs of the monocular motion SF channels are combined before analyzing the IOVD. The presumption was confirmed by the disappearance of the 3D MAE after exposure to superimposed gratings with different spatial frequencies moving in opposite directions. The direction of the 2D MAE depended on the test spatial frequency in the same condition. These results suggest that the IOVD is calculated at a relatively later stage of the motion analysis, and that some monocular information is preserved even after the integration of the motion SF channel outputs.

  9. Shoulder reflexes

    DEFF Research Database (Denmark)

    Diederichsen, Louise; Krogsgaard, Michael; Voigt, Michael

    2002-01-01

    Dynamic shoulder stability is dependent on muscular coordination and sensory inputs. In the shoulder, mechanoreceptors are found in the coracoacromial ligament, the rotator cuff tendons, the musculotendinous junctions of the rotator cuff and in the capsule. The number of receptors in the capsule...... is small compared to the number in the other shoulder structures. Proprioceptive information from numerous receptors in muscles and tendons is mediated via fast conducting nervefibers and probably contribute more to kinaestethic sensation than information from capsule and ligaments. Therefore it seems...... likely that the joint receptors have a more distinct role for the kinaestethic sense than muscle receptors. In cats a direct reflex from the afferents innervating the shoulder to the muscles around the shoulder has been presented. The reflex had an extremely short latency (2.7-3.1 ms). In man, a very...

  10. Muscle and reflex changes with varying joint angle in hemiparetic stroke

    Directory of Open Access Journals (Sweden)

    Alibiglou Laila

    2008-02-01

    Full Text Available Abstract Background Despite intensive investigation, the origins of the neuromuscular abnormalities associated with spasticity are not well understood. In particular, the mechanical properties induced by stretch reflex activity have been especially difficult to study because of a lack of accurate tools separating reflex torque from torque generated by musculo-tendinous structures. The present study addresses this deficit by characterizing the contribution of neural and muscular components to the abnormally high stiffness of the spastic joint. Methods Using system identification techniques, we characterized the neuromuscular abnormalities associated with spasticity of ankle muscles in chronic hemiparetic stroke survivors. In particular, we systematically tracked changes in muscle mechanical properties and in stretch reflex activity during changes in ankle joint angle. Modulation of mechanical properties was assessed by applying perturbations at different initial angles, over the entire range of motion (ROM. Experiments were performed on both paretic and non-paretic sides of stroke survivors, and in healthy controls. Results Both reflex and intrinsic muscle stiffnesses were significantly greater in the spastic/paretic ankle than on the non-paretic side, and these changes were strongly position dependent. The major reflex contributions were observed over the central portion of the angular range, while the intrinsic contributions were most pronounced with the ankle in the dorsiflexed position. Conclusion In spastic ankle muscles, the abnormalities in intrinsic and reflex components of joint torque varied systematically with changing position over the full angular range of motion, indicating that clinical perceptions of increased tone may have quite different origins depending upon the angle where the tests are initiated. Furthermore, reflex stiffness was considerably larger in the non-paretic limb of stroke patients than in healthy control subjects

  11. Can headway reduction in fog be explained by impaired perception of relative motion?

    Science.gov (United States)

    Caro, Stéphane; Cavallo, Viola; Marendaz, Christian; Boer, Erwin R; Vienne, Fabrice

    2009-06-01

    The goal of this study was to provide a better understanding of driver behavior in fog. Impaired perception of changes in headway is hypothesized to be one of the reasons for shorter following distances in foggy conditions as compared with clear weather. In the experiments described here, we measured response time for discriminating between whether the vehicle ahead is getting closer or farther away. Several visibility conditions were studied, ranging from a no-fog condition to a condition in which the vehicle could be seen only by its rear fog lights. Fog conditions increased response times when the outline of the vehicle was barely visible or not visible at all. The longer response times in fog were attributable to the low contrast of the vehicle outline when still visible and to the smaller spacing between the two lights when the outline could not be properly perceived. Moreover, response times were found to be shorter for shorter following distances and for faster accelerations. Reducing headway could be a way for drivers to achieve faster discrimination of relative motion in foggy weather. More specifically, shortening one's following distance until visibility of the lead vehicle changes from bad to good may have a perceptual control benefit, insofar as the response time gain compensates for the reduction in headway under these conditions. Potential applications include improving traffic safety. The results provide a possible explanation for close following in fog and point out the importance of rear-light design under these conditions.

  12. Real-time tracking using stereo and motion: Visual perception for space robotics

    Science.gov (United States)

    Nishihara, H. Keith; Thomas, Hans; Huber, Eric; Reid, C. Ann

    1994-01-01

    The state-of-the-art in computing technology is rapidly attaining the performance necessary to implement many early vision algorithms at real-time rates. This new capability is helping to accelerate progress in vision research by improving our ability to evaluate the performance of algorithms in dynamic environments. In particular, we are becoming much more aware of the relative stability of various visual measurements in the presence of camera motion and system noise. This new processing speed is also allowing us to raise our sights toward accomplishing much higher-level processing tasks, such as figure-ground separation and active object tracking, in real-time. This paper describes a methodology for using early visual measurements to accomplish higher-level tasks; it then presents an overview of the high-speed accelerators developed at Teleos to support early visual measurements. The final section describes the successful deployment of a real-time vision system to provide visual perception for the Extravehicular Activity Helper/Retriever robotic system in tests aboard NASA's KC135 reduced gravity aircraft.

  13. Procedural Audio in Computer Games Using Motion Controllers: An Evaluation on the Effect and Perception

    Directory of Open Access Journals (Sweden)

    Niels Böttcher

    2013-01-01

    Full Text Available A study has been conducted into whether the use of procedural audio affects players in computer games using motion controllers. It was investigated whether or not (1 players perceive a difference between detailed and interactive procedural audio and prerecorded audio, (2 the use of procedural audio affects their motor-behavior, and (3 procedural audio affects their perception of control. Three experimental surveys were devised, two consisting of game sessions and the third consisting of watching videos of gameplay. A skiing game controlled by a Nintendo Wii balance board and a sword-fighting game controlled by a Wii remote were implemented with two versions of sound, one sample based and the other procedural based. The procedural models were designed using a perceptual approach and by alternative combinations of well-known synthesis techniques. The experimental results showed that, when being actively involved in playing or purely observing a video recording of a game, the majority of participants did not notice any difference in sound. Additionally, it was not possible to show that the use of procedural audio caused any consistent change in the motor behavior. In the skiing experiment, a portion of players perceived the control of the procedural version as being more sensitive.

  14. The difference between the perception of absolute and relative motion: A reaction time study

    NARCIS (Netherlands)

    J.B. Smeets (Jeroen); E. Brenner (Eli)

    1994-01-01

    textabstractWe used a reaction-time paradigm to examine the extent to which motion detection depends on relative motion. In the absence of relative motion, the responses could be described by a simple model based on the detection of a fixed change in position. If relative motion was present, the res

  15. The 50s cliff: a decline in perceptuo-motor learning, not a deficit in visual motion perception.

    Directory of Open Access Journals (Sweden)

    Jie Ren

    Full Text Available Previously, we measured perceptuo-motor learning rates across the lifespan and found a sudden drop in learning rates between ages 50 and 60, called the "50s cliff." The task was a unimanual visual rhythmic coordination task in which participants used a joystick to oscillate one dot in a display in coordination with another dot oscillated by a computer. Participants learned to produce a coordination with a 90° relative phase relation between the dots. Learning rates for participants over 60 were half those of younger participants. Given existing evidence for visual motion perception deficits in people over 60 and the role of visual motion perception in the coordination task, it remained unclear whether the 50s cliff reflected onset of this deficit or a genuine decline in perceptuo-motor learning. The current work addressed this question. Two groups of 12 participants in each of four age ranges (20s, 50s, 60s, 70s learned to perform a bimanual coordination of 90° relative phase. One group trained with only haptic information and the other group with both haptic and visual information about relative phase. Both groups were tested in both information conditions at baseline and post-test. If the 50s cliff was caused by an age dependent deficit in visual motion perception, then older participants in the visual group should have exhibited less learning than those in the haptic group, which should not exhibit the 50s cliff, and older participants in both groups should have performed less well when tested with visual information. Neither of these expectations was confirmed by the results, so we concluded that the 50s cliff reflects a genuine decline in perceptuo-motor learning with aging, not the onset of a deficit in visual motion perception.

  16. The Models of Biological Motion Perception%生物运动信息加工模型

    Institute of Scientific and Technical Information of China (English)

    陈婷婷; 丁锦红; 蒋长妤

    2012-01-01

    人类可以从生物体的各种运动行为中获得丰富的社会信息,以满足社会交往的需求。视觉系统对生物运动信息的加工是一个复杂的过程,不同于对其他普通客体的加工能力。研究者们采用不同的方法,分别从各自的角度来研究这一过程,同时也建立了一系列模型。其中早期模型关注视觉系统加工生物运动信息的过程和方法;近期模型则采用脑成像手段构建生物运动信息加工的神经网络。这些模型包含了很多有价值的研究成果,但是也存在需要进一步完善的地方。%The perception of biological motion is crucial to the survival of human beings. Examining the models of biological motion perception is helpful to understanding the complex process. Previous models emphasize how the visual system encodes biological motion. The kinetic-geometric model for visual vector analysis that originally developed in the study of perception of motion combinations of the mechanical type was applied to these biological motion patterns. For the " planarity assumption" in the interpretation of biological motion, the specific problem addressed is how the three-dimensional structure and motions of animal limbs may be computed from the twodimensional motions of their projected images. Most recent studies take into account the neural mechanism of biological motion perception. The hierarchical neural model by Giese and Poggio uses a neurophysiologically plausible and quantitative model as a tool for organizing and making sense of the experimental data, despite their growing size and complexity. The template-matching model from configural form cues is addressed by Lange and Lappe. They presented a computational model based on neurally plausible assumptions to elucidate the contributions of motion and form signals to biological motion perception and the computations in the underlying brain network. The model simulates receptive fields for images of

  17. Plasticity of the cervico-ocular reflex in health and Disease

    NARCIS (Netherlands)

    W.P.A. Kelders (Willem)

    2006-01-01

    textabstractThe cervico-ocular reflex (COR) is an ocular stabilization reflex that is elicited by rotation of the neck. It works in conjunction with the vestibulo-ocular reflex (VOR) and the optokinetic reflex (OKR) in order to prevent visual slip over the retina due to self motion. The VOR

  18. A computational model for reference-frame synthesis with applications to motion perception.

    Science.gov (United States)

    Clarke, Aaron M; Öğmen, Haluk; Herzog, Michael H

    2016-09-01

    As discovered by the Gestaltists, in particular by Duncker, we often perceive motion to be within a non-retinotopic reference frame. For example, the motion of a reflector on a bicycle appears to be circular, whereas, it traces out a cycloidal path with respect to external world coordinates. The reflector motion appears to be circular because the human brain subtracts the horizontal motion of the bicycle from the reflector motion. The bicycle serves as a reference frame for the reflector motion. Here, we present a general mathematical framework, based on vector fields, to explain non-retinotopic motion processing. Using four types of non-retinotopic motion paradigms, we show how the theory works in detail. For example, we show how non-retinotopic motion in the Ternus-Pikler display can be computed.

  19. Shared computational mechanism for tilt compensation accounts for biased verticality percepts in motion and pattern vision

    NARCIS (Netherlands)

    Vrijer, M. de; Medendorp, W.P.; Gisbergen, J.A.M. van

    2008-01-01

    To determine the direction of object motion in external space, the brain must combine retinal motion signals and information about the orientation of the eyes in space. We assessed the accuracy of this process in eight laterally tilted subjects who aligned the motion direction of a random-dot patter

  20. Shared computational mechanism for tilt compensation accounts for biased verticality percepts in motion and pattern vision.

    NARCIS (Netherlands)

    Vrijer, M. de; Medendorp, W.P.; Gisbergen, J.A.M. van

    2008-01-01

    To determine the direction of object motion in external space, the brain must combine retinal motion signals and information about the orientation of the eyes in space. We assessed the accuracy of this process in eight laterally tilted subjects who aligned the motion direction of a random-dot patter

  1. Visual Cues of Motion That Trigger Animacy Perception at Birth: The Case of Self-Propulsion

    Science.gov (United States)

    Di Giorgio, Elisa; Lunghi, Marco; Simion, Francesca; Vallortigara, Giorgio

    2017-01-01

    Self-propelled motion is a powerful cue that conveys information that an object is animate. In this case, animate refers to an entity's capacity to initiate motion without an applied external force. Sensitivity to this motion cue is present in infants that are a few months old, but whether this sensitivity is experience-dependent or is already…

  2. WEAKLY ALGEBRAIC REFLEXIVITY AND STRONGLY ALGEBRAIC REFLEXIVITY

    Institute of Scientific and Technical Information of China (English)

    TaoChangli; LuShijie; ChenPeixin

    2002-01-01

    Algebraic reflexivity introduced by Hadwin is related to linear interpolation. In this paper, the concepts of weakly algebraic reflexivity and strongly algebraic reflexivity which are also related to linear interpolation are introduced. Some properties of them are obtained and some relations between them revealed.

  3. Time-perception network and default mode network are associated with temporal prediction in a periodic motion task

    Directory of Open Access Journals (Sweden)

    Fabiana Mesquita Carvalho

    2016-06-01

    Full Text Available The updating of prospective internal models is necessary to accurately predict future observations. Uncertainty-driven internal model updating has been studied using a variety of perceptual paradigms, and have revealed engagement of frontal and parietal areas. In a distinct literature, studies on temporal expectations have also characterized a time-perception network, which relies on temporal orienting of attention. However, the updating of prospective internal models is highly dependent on temporal attention, since temporal attention must be reoriented according to the current environmental demands. In this study we used fMRI to evaluate to what extend the continuous manipulation of temporal prediction would recruit update-related areas and the time-perception network areas. We developed an exogenous temporal task that combines rhythm cueing and time-to-contact principles to generate implicit temporal expectation. Two patterns of motion were created: periodic (simple harmonic oscillation and non-periodic (harmonic oscillation with variable acceleration. We found that non-periodic motion engaged the exogenous temporal orienting network, which includes the ventral premotor and inferior parietal cortices, and the cerebellum, as well as the presupplementary motor area, which has previously been implicated in internal model updating, and the motion-sensitive area MT+. Interestingly, we found a right-hemisphere preponderance suggesting the engagement of explicit timing mechanisms. We also show that the periodic motion condition, when compared to the non-periodic motion, activated a particular subset of the default-mode network (DMN midline areas, including the left dorsomedial prefrontal cortex, anterior cingulate cortex, and bilateral posterior cingulate cortex/precuneus. It suggests that the DMN plays a role in processing contextually expected information and supports recent evidence that the DMN may reflect the validation of prospective internal

  4. Reflexes in Psychiatry

    OpenAIRE

    Sanders, Richard D.; Gillig, Paulette Marie

    2011-01-01

    Psychiatric patients often do not cooperate fully with the neurologic examination. Reflexes virtually bypass patient effort and are difficult to consciously determine. This article reviews muscle stretch (deep tendon) reflexes, and pathological reflexes including the extensor plantar (Babinski) and primitive release reflexes. Topics include findings in common psychiatric and neurologic conditions and methods for eliciting these signs.

  5. Reflexive cacti: a survey

    OpenAIRE

    Bojana Mihailović; Marija Rašajski; Zoran Stanić

    2016-01-01

    A graph is called reflexive if its second largest eigenvalue does not exceed 2. We survey the results on reflexive cacti obtained in the last two decades. We also discuss various patterns of appearing of Smith graphs as subgraphs of reflexive cacti. In the Appendix, we survey the recent results concerning reflexive bipartite regular graphs.

  6. The nasocardiac reflex.

    Science.gov (United States)

    Baxandall, M L; Thorn, J L

    1988-06-01

    The oculocardiac reflex is well described and recognised in anaesthesia. The nasocardiac reflex is less well-known. We describe a clinical manifestation of this reflex and describe the relevant anatomy. This reflex may be obtunded during general anaesthesia. during general anaesthesia.

  7. Reflexives in Veracruz Huastec.

    Science.gov (United States)

    Constable, Peter G.

    A study examines various Huastec clause types that are reflexive in some sense, including ordinary reflexives, which involve co-reference. Two mutually exclusive morphosyntactic devices are used in Huastec: reflexive pronouns and verbal morphology. In this way, Huastec is like various European languages. Clauses involving reflexive pronouns and…

  8. Dorsal stream vulnerability in preterm infants – A longitudinal EEG study of visual motion perception

    OpenAIRE

    Zotcheva, Ekaterina

    2015-01-01

    High-density electroencephalogram (EEG) was used to longitudinally investigate evoked and induced brain electrical activity as a function of visual motion in full-term and preterm infants at 4-5 and 12 months of age. The infants were presented with two visual motion paradigms, optic flow and looming. The optic flow experiment simulated structured forwards and reversed optic flow and random visual motion, while the looming experiment simulated a looming object approaching on a direct collision...

  9. Full-wave and half-wave rectification in second-order motion perception

    Science.gov (United States)

    Solomon, J. A.; Sperling, G.

    1994-01-01

    Microbalanced stimuli are dynamic displays which do not stimulate motion mechanisms that apply standard (Fourier-energy or autocorrelational) motion analysis directly to the visual signal. In order to extract motion information from microbalanced stimuli, Chubb and Sperling [(1988) Journal of the Optical Society of America, 5, 1986-2006] proposed that the human visual system performs a rectifying transformation on the visual signal prior to standard motion analysis. The current research employs two novel types of microbalanced stimuli: half-wave stimuli preserve motion information following half-wave rectification (with a threshold) but lose motion information following full-wave rectification; full-wave stimuli preserve motion information following full-wave rectification but lose motion information following half-wave rectification. Additionally, Fourier stimuli, ordinary square-wave gratings, were used to stimulate standard motion mechanisms. Psychometric functions (direction discrimination vs stimulus contrast) were obtained for each type of stimulus when presented alone, and when masked by each of the other stimuli (presented as moving masks and also as nonmoving, counterphase-flickering masks). RESULTS: given sufficient contrast, all three types of stimulus convey motion. However, only one-third of the population can perceive the motion of the half-wave stimulus. Observers are able to process the motion information contained in the Fourier stimulus slightly more efficiently than the information in the full-wave stimulus but are much less efficient in processing half-wave motion information. Moving masks are more effective than counterphase masks at hampering direction discrimination, indicating that some of the masking effect is interference between motion mechanisms, and some occurs at earlier stages. When either full-wave and Fourier or half-wave and Fourier gratings are presented simultaneously, there is a wide range of relative contrasts within which the

  10. Stream/bounce event perception reveals a temporal limit of motion correspondence based on surface feature over space and time.

    Science.gov (United States)

    Kawachi, Yousuke; Kawabe, Takahiro; Gyoba, Jiro

    2011-01-01

    We examined how stream/bounce event perception is affected by motion correspondence based on the surface features of moving objects passing behind an occlusion. In the stream/bounce display two identical objects moving across each other in a two-dimensional display can be perceived as either streaming through or bouncing off each other at coincidence. Here, surface features such as colour (Experiments 1 and 2) or luminance (Experiment 3) were switched between the two objects at coincidence. The moment of coincidence was invisible to observers due to an occluder. Additionally, the presentation of the moving objects was manipulated in duration after the feature switch at coincidence. The results revealed that a postcoincidence duration of approximately 200 ms was required for the visual system to stabilize judgments of stream/bounce events by determining motion correspondence between the objects across the occlusion on the basis of the surface feature. The critical duration was similar across motion speeds of objects and types of surface features. Moreover, controls (Experiments 4a-4c) showed that cognitive bias based on feature (colour/luminance) congruency across the occlusion could not fully account for the effects of surface features on the stream/bounce judgments. We discuss the roles of motion correspondence, visual feature processing, and attentive tracking in the stream/bounce judgments.

  11. Stream/Bounce Event Perception Reveals a Temporal Limit of Motion Correspondence Based on Surface Feature over Space and Time

    Directory of Open Access Journals (Sweden)

    Yousuke Kawachi

    2011-06-01

    Full Text Available We examined how stream/bounce event perception is affected by motion correspondence based on the surface features of moving objects passing behind an occlusion. In the stream/bounce display two identical objects moving across each other in a two-dimensional display can be perceived as either streaming through or bouncing off each other at coincidence. Here, surface features such as colour (Experiments 1 and 2 or luminance (Experiment 3 were switched between the two objects at coincidence. The moment of coincidence was invisible to observers due to an occluder. Additionally, the presentation of the moving objects was manipulated in duration after the feature switch at coincidence. The results revealed that a postcoincidence duration of approximately 200 ms was required for the visual system to stabilize judgments of stream/bounce events by determining motion correspondence between the objects across the occlusion on the basis of the surface feature. The critical duration was similar across motion speeds of objects and types of surface features. Moreover, controls (Experiments 4a–4c showed that cognitive bias based on feature (colour/luminance congruency across the occlusion could not fully account for the effects of surface features on the stream/bounce judgments. We discuss the roles of motion correspondence, visual feature processing, and attentive tracking in the stream/bounce judgments.

  12. Complete sparing of high-contrast color input to motion perception in cortical color blindness.

    Science.gov (United States)

    Cavanagh, P; Hénaff, M A; Michel, F; Landis, T; Troscianko, T; Intriligator, J

    1998-07-01

    It is widely held that color and motion are processed by separate parallel pathways in the visual system, but this view is difficult to reconcile with the fact that motion can be detected in equiluminant stimuli that are defined by color alone. To examine the relationship between color and motion, we tested three patients who had lost their color vision following cortical damage (central achromatopsia). Despite their profound loss in the subjective experience of color and their inability to detect the motion of faint colors, all three subjects showed surprisingly strong responses to high-contrast, moving color stimuli--equal in all respects to the performance of subjects with normal color vision. The pathway from opponent-color detectors in the retina to the motion analysis areas must therefore be independent of the damaged color centers in the occipitotemporal area. It is probably also independent of the motion analysis area MT/V5, because the contribution of color to motion detection in these patients is much stronger than the color response of monkey area MT.

  13. Perceptual rivalry: reflexes reveal the gradual nature of visual awareness.

    Directory of Open Access Journals (Sweden)

    Marnix Naber

    Full Text Available Rivalry is a common tool to probe visual awareness: a constant physical stimulus evokes multiple, distinct perceptual interpretations ("percepts" that alternate over time. Percepts are typically described as mutually exclusive, suggesting that a discrete (all-or-none process underlies changes in visual awareness. Here we follow two strategies to address whether rivalry is an all-or-none process: first, we introduce two reflexes as objective measures of rivalry, pupil dilation and optokinetic nystagmus (OKN; second, we use a continuous input device (analog joystick to allow observers a gradual subjective report. We find that the "reflexes" reflect the percept rather than the physical stimulus. Both reflexes show a gradual dependence on the time relative to perceptual transitions. Similarly, observers' joystick deflections, which are highly correlated with the reflex measures, indicate gradual transitions. Physically simulating wave-like transitions between percepts suggest piece-meal rivalry (i.e., different regions of space belonging to distinct percepts as one possible explanation for the gradual transitions. Furthermore, the reflexes show that dominance durations depend on whether or not the percept is actively reported. In addition, reflexes respond to transitions with shorter latencies than the subjective report and show an abundance of short dominance durations. This failure to report fast changes in dominance may result from limited access of introspection to rivalry dynamics. In sum, reflexes reveal that rivalry is a gradual process, rivalry's dynamics is modulated by the required action (response mode, and that rapid transitions in perceptual dominance can slip away from awareness.

  14. A neural model of the temporal dynamics of figure-ground segregation in motion perception.

    Science.gov (United States)

    Raudies, Florian; Neumann, Heiko

    2010-03-01

    How does the visual system manage to segment a visual scene into surfaces and objects and manage to attend to a target object? Based on psychological and physiological investigations, it has been proposed that the perceptual organization and segmentation of a scene is achieved by the processing at different levels of the visual cortical hierarchy. According to this, motion onset detection, motion-defined shape segregation, and target selection are accomplished by processes which bind together simple features into fragments of increasingly complex configurations at different levels in the processing hierarchy. As an alternative to this hierarchical processing hypothesis, it has been proposed that the processing stages for feature detection and segregation are reflected in different temporal episodes in the response patterns of individual neurons. Such temporal epochs have been observed in the activation pattern of neurons as low as in area V1. Here, we present a neural network model of motion detection, figure-ground segregation and attentive selection which explains these response patterns in an unifying framework. Based on known principles of functional architecture of the visual cortex, we propose that initial motion and motion boundaries are detected at different and hierarchically organized stages in the dorsal pathway. Visual shapes that are defined by boundaries, which were generated from juxtaposed opponent motions, are represented at different stages in the ventral pathway. Model areas in the different pathways interact through feedforward and modulating feedback, while mutual interactions enable the communication between motion and form representations. Selective attention is devoted to shape representations by sending modulating feedback signals from higher levels (working memory) to intermediate levels to enhance their responses. Areas in the motion and form pathway are coupled through top-down feedback with V1 cells at the bottom end of the hierarchy

  15. Inferred motion perception of light sources in 3D scenes is color-blind.

    Science.gov (United States)

    Gerhard, Holly E; Maloney, Laurence T

    2013-01-01

    In everyday scenes, the illuminant can vary spatially in chromaticity and luminance, and change over time (e.g. sunset). Such variation generates dramatic image effects too complex for any contemporary machine vision system to overcome, yet human observers are remarkably successful at inferring object properties separately from lighting, an ability linked with estimation and tracking of light field parameters. Which information does the visual system use to infer light field dynamics? Here, we specifically ask whether color contributes to inferred light source motion. Observers viewed 3D surfaces illuminated by an out-of-view moving collimated source (sun) and a diffuse source (sky). In half of the trials, the two sources differed in chromaticity, thereby providing more information about motion direction. Observers discriminated light motion direction above chance, and only the least sensitive observer benefited slightly from the added color information, suggesting that color plays only a very minor role for inferring light field dynamics.

  16. Inferred Motion Perception of Light Sources in 3D Scenes is Color-Blind

    Directory of Open Access Journals (Sweden)

    Holly E. Gerhard

    2013-04-01

    Full Text Available In everyday scenes, the illuminant can vary spatially in chromaticity and luminance, and change over time (e.g. sunset. Such variation generates dramatic image effects too complex for any contemporary machine vision system to overcome, yet human observers are remarkably successful at inferring object properties separately from lighting, an ability linked with estimation and tracking of light field parameters. Which information does the visual system use to infer light field dynamics? Here, we specifically ask whether color contributes to inferred light source motion. Observers viewed 3D surfaces illuminated by an out-of-view moving collimated source (sun and a diffuse source (sky. In half of the trials, the two sources differed in chromaticity, thereby providing more information about motion direction. Observers discriminated light motion direction above chance, and only the least sensitive observer benefited slightly from the added color information, suggesting that color plays only a very minor role for inferring light field dynamics.

  17. Velocity of motion across the skin influences perception of tactile location.

    Science.gov (United States)

    Nguyen, Elizabeth H L; Taylor, Janet L; Brooks, Jack; Seizova-Cajic, Tatjana

    2016-02-01

    We investigated the influence of motion context on tactile localization, using a paradigm similar to the cutaneous rabbit or sensory saltation (Geldard FA, Sherrick CE. Science 178: 178-179, 1972). In one of its forms, the rabbit stimulus consists of a tap in one location quickly followed by another tap elsewhere, creating the illusion that the two taps are near each other. Instead of taps, we used position of a halted brush and instead of distance judgment, localization responses. The brush moved across the skin of the left forearm, creating a clear motion signal before and after a rabbitlike leap of 10 cm (at 100 cm/s). Three before-and-after velocities (7.5, 15, or 30 cm/s) were used. Participants (n = 13) pointed with their right arm at the felt location of the brush when it halted either 1 cm before or after the leap. These stops were 12 cm apart, but distances computed from localization responses were only 5.4, 6.5, and 7.5 cm for the three velocities, respectively (F[2,11] = 15.19, P = 0.001). Thus the leap resulted in compressive position shift, as described previously for sensory saltation, but modulated by motion velocity before the leap: the slower the motion, the greater the shift opposite to motion direction. No gap in stimulation was perceived. We propose that velocity extrapolation causes the position shift: extrapolated motion does not have enough time to bridge the real spatial gap and thus assigns a closer location to the skin on the opposite side of the gap.

  18. Human otolith-ocular reflexes during off-vertical axis rotation: effect of frequency on tilt-translation ambiguity and motion sickness

    Science.gov (United States)

    Wood, Scott J.; Paloski, W. H. (Principal Investigator)

    2002-01-01

    The purpose of this study was to examine how the modulation of tilt and translation otolith-ocular responses during constant velocity off-vertical axis rotation varies as a function of stimulus frequency. Eighteen human subjects were rotated in darkness about their longitudinal axis 30 degrees off-vertical at stimulus frequencies between 0.05 and 0.8 Hz. The modulation of torsion decreased while the modulation of horizontal slow phase velocity (SPV) increased with increasing frequency. It is inferred that the ambiguity of otolith afferent information is greatest in the frequency region where tilt (torsion) and translational (horizontal SPV) otolith-ocular responses crossover. It is postulated that the previously demonstrated peak in motion sickness susceptibility during linear accelerations around 0.3 Hz is the result of frequency segregation of ambiguous otolith information being inadequate to distinguish between tilt and translation.

  19. Embodied Self-Reflexivity

    Science.gov (United States)

    Pagis, Michal

    2009-01-01

    Drawing on G. H. Mead and Merleau-Ponty, this paper aims to extend our understanding of self-reflexivity beyond the notion of a discursive, abstract, and symbolic process. It offers a framework for embodied self-reflexivity, which anchors the self in the reflexive capacity of bodily sensations. The data consist of two years of ethnographic…

  20. The Bicycle Illusion: Sidewalk Science Informs the Integration of Motion and Shape Perception

    Science.gov (United States)

    Masson, Michael E. J.; Dodd, Michael D.; Enns, James T.

    2009-01-01

    The authors describe a new visual illusion first discovered in a natural setting. A cyclist riding beside a pair of sagging chains that connect fence posts appears to move up and down with the chains. In this illusion, a static shape (the chains) affects the perception of a moving shape (the bicycle), and this influence involves assimilation…

  1. Perception of animacy from the motion of a single sound object

    DEFF Research Database (Denmark)

    Nielsen, Rasmus Høll; Vuust, Peter; Wallentin, Mikkel

    2015-01-01

    generated “mosquito” sounds moving along trajectories in space, and asked to rate how certain they were that each sound emitting entity was alive. At a random point on a linear motion trajectory, the sound source would deviate from its initial path and speed. Results confirm findings from the visual domain...

  2. Perception of Animacy from the Motion of a Single Sound Object.

    Science.gov (United States)

    Nielsen, Rasmus Høll; Vuust, Peter; Wallentin, Mikkel

    2015-02-01

    Research in the visual modality has shown that the presence of certain dynamics in the motion of an object has a strong effect on whether or not the entity is perceived as animate. Cues for animacy are, among others, self-propelled motion and direction changes that are seemingly not caused by entities external to, or in direct contact with, the moving object. The present study aimed to extend this research into the auditory domain by determining if similar dynamics could influence the perceived animacy of a sound source. In two experiments, participants were presented with single, synthetically generated 'mosquito' sounds moving along trajectories in space, and asked to rate how certain they were that each sound-emitting entity was alive. At a random point on a linear motion trajectory, the sound source would deviate from its initial path and speed. Results confirm findings from the visual domain that a change in the velocity of motion is positively correlated with perceived animacy, and changes in direction were found to influence animacy judgment as well. This suggests that an ability to facilitate and sustain self-movement is perceived as a living quality not only in the visual domain, but in the auditory domain as well.

  3. Effects of environmental context on temporal perception bias in apparent motion.

    Science.gov (United States)

    Masuda, Tomohiro; Kimura, Atsushi; Dan, Ippeita; Wada, Yuji

    2011-08-01

    We investigated whether the directional effect on the kappa effect can be attributed to the directional anisotropy of retinotopical space or to the representation of forces provided by environmental contexts (e.g., gravity) in an observed event. We examined whether different contexts with similar directional changes (straight vs. reversed motion) influence the kappa effect in four experiments. The object's motion appeared to depict only forces under the natural laws of physics on a slope (Experiment 1) or on a horizontal plane (Experiment 2) in virtual 3D space. In Experiments 3 and 4, the motion appeared to be subjected to external or self-driving forces additionally influenced by internal forces on a slope (Experiment 3) or a horizontal plane (Experiment 4). The results demonstrated that the directional effect on the kappa effect was observed only in Experiment 1, and not in Experiments 2 and 3, while the kappa effect was preserved. Furthermore, not even the kappa effect was observed in the reversed motion of Experiment 4. The results of the present study suggest that the determining factor of direction in the kappa effect is not a simple anisotropy, but rather the context of observed events. Copyright © 2011 Elsevier Ltd. All rights reserved.

  4. The Perception of Prototypical Motion: Synchronization Is Enhanced with Quantitatively Morphed Gestures of Musical Conductors

    Science.gov (United States)

    Wollner, Clemens; Deconinck, Frederik J. A.; Parkinson, Jim; Hove, Michael J.; Keller, Peter E.

    2012-01-01

    Aesthetic theories have long suggested perceptual advantages for prototypical exemplars of a given class of objects or events. Empirical evidence confirmed that morphed (quantitatively averaged) human faces, musical interpretations, and human voices are preferred over most individual ones. In this study, biological human motion was morphed and…

  5. Auditory Motion Elicits a Visual Motion Aftereffect

    Directory of Open Access Journals (Sweden)

    Christopher C. Berger

    2016-12-01

    Full Text Available The visual motion aftereffect is a visual illusion in which exposure to continuous motion in one direction leads to a subsequent illusion of visual motion in the opposite direction. Previous findings have been mixed with regard to whether this visual illusion can be induced cross-modally by auditory stimuli. Based on research on multisensory perception demonstrating the profound influence auditory perception can have on the interpretation and perceived motion of visual stimuli, we hypothesized that exposure to auditory stimuli with strong directional motion cues should induce a visual motion aftereffect. Here, we demonstrate that horizontally moving auditory stimuli induced a significant visual motion aftereffect—an effect that was driven primarily by a change in visual motion perception following exposure to leftward moving auditory stimuli. This finding is consistent with the notion that visual and auditory motion perception rely on at least partially overlapping neural substrates.

  6. Shape beyond recognition: form-derived directionality and its effects on visual attention and motion perception.

    Science.gov (United States)

    Sigurdardottir, Heida M; Michalak, Suzanne M; Sheinberg, David L

    2014-02-01

    The shape of an object restricts its movements and therefore its future location. The rules governing selective sampling of the environment likely incorporate any available data, including shape, that provide information about where important things are going to be in the near future so that the object can be located, tracked, and sampled for information. We asked people to assess in which direction several novel objects pointed or directed them. With independent groups of people, we investigated whether their attention and sense of motion were systematically biased in this direction. Our work shows that nearly any novel object has intrinsic directionality derived from its shape. This shape information is swiftly and automatically incorporated into the allocation of overt and covert visual orienting and the detection of motion, processes that themselves are inherently directional. The observed connection between form and space suggests that shape processing goes beyond recognition alone and may help explain why shape is a relevant dimension throughout the visual brain.

  7. Motion Perception and Driving: Predicting Performance Through Testing and Shortening Braking Reaction Times Through Training

    Science.gov (United States)

    2013-12-01

    to deficits in a variety of conditions for which standard VA is normal. These include amblyopia,29 early enucleation,30 multiple sclerosis,31 and...Factors. 1991;33:507–519. 11. Sanderson FH, Whiting HTA . Dynamic visual-acuity – possible factor in catching performance. J Motor Behav. 1978;10:7–14. 12...2489. 30. Steeves JKE, Gonzalez EG, Gallie BL, Steinbach MJ. Early unilateral enucleation disrupts motion processing. Vision Res. 2002;42:143–150. 31

  8. Illusory Tactile Motion Perception: An Analog of the Visual Filehne Illusion.

    Science.gov (United States)

    Moscatelli, Alessandro; Hayward, Vincent; Wexler, Mark; Ernst, Marc O

    2015-09-28

    We continually move our body and our eyes when exploring the world, causing our sensory surfaces, the skin and the retina, to move relative to external objects. In order to estimate object motion consistently, an ideal observer would transform estimates of motion acquired from the sensory surface into fixed, world-centered estimates, by taking the motion of the sensor into account. This ability is referred to as spatial constancy. Human vision does not follow this rule strictly and is therefore subject to perceptual illusions during eye movements, where immobile objects can appear to move. Here, we investigated whether one of these, the Filehne illusion, had a counterpart in touch. To this end, observers estimated the movement of a surface from tactile slip, with a moving or with a stationary finger. We found the perceived movement of the surface to be biased if the surface was sensed while moving. This effect exemplifies a failure of spatial constancy that is similar to the Filehne illusion in vision. We quantified this illusion by using a Bayesian model with a prior for stationarity, applied previously in vision. The analogy between vision and touch points to a modality-independent solution to the spatial constancy problem.

  9. The Oculus Rift: A cost-effective tool for studying visual-vestibular interactions in self-motion perception

    Directory of Open Access Journals (Sweden)

    Juno eKim

    2015-03-01

    Full Text Available For years now, virtual reality devices have been applied in the field of vision science in an attempt to improve our understanding of perceptual principles underlying the experience of self-motion. Some of this research has been concerned with exploring factors involved in the visually-induced illusory perception of self-motion, known as vection. We examined the usefulness of the cost-effective Oculus Rift in generating vection in seated observers. This device has the capacity to display optic flow in world coordinates by compensating for tracked changes in 3D head orientation. We measured vection strength in three conditions of visual compensation for head movement: compensated, uncompensated, and inversely compensated. During presentation of optic flow, the observer was instructed to make periodic head oscillations (+/- 22 deg horizontal excursions at approximately 0.53 Hz. We found that vection was best in the compensated condition, and was weakest in the inversely compensated condition. Surprisingly, vection was always better in passive viewing conditions, compared with conditions where active head rotations were performed. These findings suggest that vection is highly dependent on interactions between visual, vestibular and proprioceptive information, and may be highly sensitive to limitations of temporal lag in visual-vestibular coupling using this system.

  10. An Exploration of the Perception of Dance and Its Relation to Biomechanical Motion: A Systematic Review and Narrative Synthesis.

    Science.gov (United States)

    Chang, Michael; Halaki, Mark; Adams, Roger; Cobley, Stephen; Lee, Kwee-Yum; O'Dwyer, Nicholas

    2016-01-01

    In dance, the goals of actions are not always clearly defined. Investigations into the perceived quality of dance actions and their relation to biomechanical motion should give insight into the performance of dance actions and their goals. The purpose of this review was to explore and document current literature concerning dance perception and its relation to the biomechanics of motion. Seven studies were included in the review. The study results showed systematic differences between expert, non-expert, and novice dancers in biomechanical and perceptual measures, both of which also varied according to the actions expressed in dance. Biomechanical and perceptual variables were found to be correlated in all the studies in the review. Significant relations were observed between kinematic variables such as amplitude, speed, and variability of movement, and perceptual measures of beauty and performance quality. However, in general, there were no clear trends in these relations. Instead, the evidence suggests that perceptual ratings of dance may be specific to both the task (the skill of the particular action) and the context (the music and staging). The results also suggest that the human perceptual system is sensitive to skillful movements and neuromuscular coordination. Since the value perceived by audiences appears to be related to dance action goals and the coordination of dance elements, practitioners could place a priority on development and execution of those factors.

  11. Emergency nurses' perceptions of the role of confidence, self-efficacy and reflexivity in managing the cognitively impaired older person in pain.

    Science.gov (United States)

    Fry, Margaret; MacGregor, Casimir; Hyland, Simone; Payne, Barbara; Chenoweth, Lynn

    2015-06-01

    The study aimed to explore the practice of care among emergency nurses caring for older persons with cognitive impairment and who presented in pain from a long bone fracture, to highlight nurse confidence and self-efficacy in practice. Cognitive impairment is an issue increasingly facing emergency departments. Older persons with cognitive impairment have complex care needs, requiring effective clinical decision-making and provision of care. Nurse confidence and self-efficacy are critical to meeting the necessary standards of care for this vulnerable patient group. A multi-centre study. The study was undertaken across four emergency departments in Sydney, Australia. Sixteen focus group discussions were conducted with 80 emergency departments of nurses. Four main themes emerged: confidence and self-efficacy through experience; confidence and self-efficacy as a balancing act; confidence and self-efficacy as practice; and confidence and self-efficacy and interpersonal relations. Our findings demonstrate that confidence, self-efficacy and reflexivity enabled the delivery of appropriate, timely and compassionate care. Further, confidence and self-efficacy within nursing praxis relied on clinical experience and reflective learning and was crucial to skill and knowledge acquisition. Our research suggests that confidence, self-efficacy and reflexivity need to be developed and valued in nurses' careers to better meet the needs of complex older persons encountered within everyday practice. © 2015 John Wiley & Sons Ltd.

  12. Both physical exercise and progressive muscle relaxation reduce the facing-the-viewer bias in biological motion perception.

    Directory of Open Access Journals (Sweden)

    Adam Heenan

    Full Text Available Biological motion stimuli, such as orthographically projected stick figure walkers, are ambiguous about their orientation in depth. The projection of a stick figure walker oriented towards the viewer, therefore, is the same as its projection when oriented away. Even though such figures are depth-ambiguous, however, observers tend to interpret them as facing towards them more often than facing away. Some have speculated that this facing-the-viewer bias may exist for sociobiological reasons: Mistaking another human as retreating when they are actually approaching could have more severe consequences than the opposite error. Implied in this hypothesis is that the facing-towards percept of biological motion stimuli is potentially more threatening. Measures of anxiety and the facing-the-viewer bias should therefore be related, as researchers have consistently found that anxious individuals display an attentional bias towards more threatening stimuli. The goal of this study was to assess whether physical exercise (Experiment 1 or an anxiety induction/reduction task (Experiment 2 would significantly affect facing-the-viewer biases. We hypothesized that both physical exercise and progressive muscle relaxation would decrease facing-the-viewer biases for full stick figure walkers, but not for bottom- or top-half-only human stimuli, as these carry less sociobiological relevance. On the other hand, we expected that the anxiety induction task (Experiment 2 would increase facing-the-viewer biases for full stick figure walkers only. In both experiments, participants completed anxiety questionnaires, exercised on a treadmill (Experiment 1 or performed an anxiety induction/reduction task (Experiment 2, and then immediately completed a perceptual task that allowed us to assess their facing-the-viewer bias. As hypothesized, we found that physical exercise and progressive muscle relaxation reduced facing-the-viewer biases for full stick figure walkers only. Our

  13. Reflexives and reflexive constructions in Afrikaans

    African Journals Online (AJOL)

    Kate H

    coreferential relationship between the pronoun and some other expression in the sentence. Keywords: reflexives ...... object argument, functions as the complement of a noun. Consider the ...... A minimalist approach to the syntax of. Dutch.

  14. Nonvisual motor learning improves visual motion perception: evidence from violating the two-thirds power law.

    Science.gov (United States)

    Beets, I A M; Rösler, F; Fiehler, K

    2010-09-01

    Few studies have reported direct effects of motor learning on visual perception, especially when using novel movements for the motor system. Atypical motor behaviors that violate movement constraints provide an excellent opportunity to study action-to-perception transfer. In our study, we passively trained blindfolded participants on movements violating the 2/3 power law. Before and after motor training, participants performed a visual discrimination task in which they decided whether two consecutive movements were same or different. For motor training, we randomly assigned the participants to two motor training groups or a control group. The motor training group experienced either a weak or a strong elliptic velocity profile on a circular trajectory that matched one of the visual test stimuli. The control group was presented with linear trajectories unrelated to the viewed movements. After each training session, participants actively reproduced the movement to assess motor learning. The group trained on the strong elliptic velocity profile reproduced movements with increasing elliptic velocity profiles while circular geometry remained constant. Furthermore, both training groups improved in visual discrimination ability for the learned movement as well as for highly similar movements. Participants in the control group, however, did not show any improvements in the visual discrimination task nor did participants who did not acquire the trained movement. The present results provide evidence for a transfer from action to perception which generalizes to highly related movements and depends on the success of motor learning. Moreover, under specific conditions, it seems to be possible to acquire movements deviating from the 2/3 power law.

  15. Beyond visual, aural and haptic movement perception: hMT+ is activated by electrotactile motion stimulation of the tongue in sighted and in congenitally blind individuals

    DEFF Research Database (Denmark)

    Matteau, Isabelle; Kupers, Ron; Ricciardi, Emiliano

    2010-01-01

    regardless of visual experience and the sensory modality through which such information is carried to the brain. Here we determined whether the hMT+ complex responds to motion perception per se, that is, motion not perceived through the visual, haptic or aural modalities. Using functional magnetic resonance...... imaging (fMRI), we investigated brain responses in eight congenitally blind and nine sighted volunteers who had been trained to use the tongue display unit (TDU), a sensory substitution device which converts visual information into electrotactile pulses delivered to the tongue, to resolve a tactile motion...... that are not visual in nature and that are administered to body structures that, in humans, are not primarily devoted to movement perception or spatial location, such as the tongue. In line with previous studies, the differential activations between sighted and congenitally blind individuals indicate that lack...

  16. Reducing magnocellular processing of various motion trajectories tests single process theories of visual position perception.

    Science.gov (United States)

    Chappell, Mark; Potter, Zach; Hine, Trevor J; Mullen, Kathy T; Shand, James

    2013-08-28

    Spatial projection and temporal integration are two prominent theories of visual localization for moving stimuli which gain most of their explanatory power from a single process. Spatial projection theories posit that a moving stimulus' perceived position is projected forwards in order to compensate for processing delays (Eagleman & Sejnowski, 2007; Nijhawan, 2008). Temporal integration theories (Krekelberg & Lappe, 2000) suggest that an averaging over positions occupied by the moving stimulus for a period of time is the dominant process underlying perception of position. We found that when magnocellular (M) pathway processing was reduced, there were opposite effects on localization judgments when a smooth, continuous trajectory was used, compared to when the moving object suddenly appeared, or suddenly reversed direction. The flash-lag illusion was decreased for the continuous trajectory, but increased for the onset and reversal trajectories. This cross-over interaction necessitates processes additional to those proposed by either the spatial projection or temporal integration theories in order to explain the perception of the position of moving stimuli across all our conditions. Differentiating our onset trajectory conditions from a Fröhlich illusion, in a second experiment, we found a null Fröhlich illusion under normal luminance-defined conditions, significantly smaller than the corresponding flash-lag illusion, but significantly increased when M processing was reduced. Our data are most readily accounted for by Kirschfeld and Kammer's (1999) backward-inhibition and focal attention theory.

  17. Intrasaccadic perception triggers pupillary constriction

    Directory of Open Access Journals (Sweden)

    Sebastiaan Mathôt

    2015-08-01

    Full Text Available It is commonly believed that vision is impaired during saccadic eye movements. However, here we report that some visual stimuli are clearly visible during saccades, and trigger a constriction of the eye’s pupil. Participants viewed sinusoid gratings that changed polarity 150 times per second (every 6.67 ms. At this rate of flicker, the gratings were perceived as homogeneous surfaces while participants fixated. However, the flickering gratings contained ambiguous motion: rightward and leftward motion for vertical gratings; upward and downward motion for horizontal gratings. When participants made a saccade perpendicular to the gratings’ orientation (e.g., a leftward saccade for a vertical grating, the eye’s peak velocity matched the gratings’ motion. As a result, the retinal image was approximately stable for a brief moment during the saccade, and this gave rise to an intrasaccadic percept: A normally invisible stimulus became visible when eye velocity was maximal. Our results confirm and extend previous studies by demonstrating intrasaccadic perception using a reflexive measure (pupillometry that does not rely on subjective report. Our results further show that intrasaccadic perception affects all stages of visual processing, from the pupillary response to visual awareness.

  18. A perturbation analysis of depth perception from combinations of texture and motion cues.

    Science.gov (United States)

    Young, M J; Landy, M S; Maloney, L T

    1993-12-01

    We examined how depth information from two different cue types (object motion and texture gradient) is integrated into a single estimate in human vision. Two critical assumptions of a recent model of depth cue combination (termed modified weak fusion) were tested. The first assumption is that the overall depth estimate is a weighted linear combination of the estimates derived from the individual cues, after initial processing needed to bring them to a common format. The second assumption is that the weight assigned to a cue reflects the apparent reliability of that cue in a particular scene. By this account, the depth combination rule is linear and dynamic, changing in a predictable fashion in response to the particular scene and viewing conditions. A novel procedure was used to measure the weights assigned to the texture and motion cues across experimental conditions. This procedure uses a type of perturbation analysis. The results are consistent with the weighted linear combination rule. In addition, when either cue is corrupted by added noise, the weighted linear combination rule shifts in favor of the uncontaminated cue.

  19. Emotionally Colorful Reflexive Games

    CERN Document Server

    Tarasenko, Sergey

    2011-01-01

    This study addresses the matter of reflexive control of the emotional states by means of Reflexive Game Theory (RGT). It is shown how to build a bridge between RGT and emotions. For this purpose the Pleasure-Arousal-Dominance (PAD) model is adopted. The major advantages of RGT are its ability to predict human behavior and unfold the entire spectra of reflexion in the human mind. On the other hand, PAD provides ultimate approach to model emotions. It is illustrated that emotions are reflexive processes and, consequently, RGT fused with PAD model is natural solution to model emotional interactions between people. The fusion of RGT and PAD, called Emotional Reflexive Games (ERG), inherits the key features of both components. Using ERG, we show how reflexive control can be successfully applied to model human emotional states. Up to date, EGR is a unique methodology capable of modeling human reflexive processes and emotional aspects simultaneously.

  20. Removal of Color Scratches from Old Motion Picture Films Exploiting Human Perception

    Directory of Open Access Journals (Sweden)

    Domenico Vitulano

    2008-09-01

    Full Text Available In this paper a unified model for both detection and restoration of line scratches on color movies is presented. It exploits a generalization of the light diffraction effect for modeling the shape of scratches, while perception laws are used for their automatic detection and removal. The detection algorithm has a high precision in terms of number of detected true scratches and reduced number of false alarms. The quality of the restored images is satisfying from a subjective (visual point of view if compared with the state-of-the-art approaches. The use of very simple operations in both detection and restoration phases makes the implemented algorithms appealing for their low computing time.

  1. Reflex excitability regulates prepulse inhibition.

    Science.gov (United States)

    Schicatano, E J; Peshori, K R; Gopalaswamy, R; Sahay, E; Evinger, C

    2000-06-01

    Presentation of a weak stimulus, a prepulse, before a reflex-evoking stimulus decreases the amplitude of the reflex response relative to reflex amplitude evoked without a preceding prepulse. For example, presenting a brief tone before a trigeminal blink-eliciting stimulus significantly reduces reflex blink amplitude. A common explanation of such data are that sensory processing of the prepulse modifies reflex circuit behavior. The current study investigates the converse hypothesis that the intrinsic characteristics of the reflex circuit rather than prepulse processing determine prepulse modification of trigeminal and acoustic reflex blinks. Unilateral lesions of substantia nigra pars compacta neurons created rats with hyperexcitable trigeminal reflex blinks but normally excitable acoustic reflex blinks. In control rats, presentation of a prepulse reduced the amplitude of both trigeminal and acoustic reflex blinks. In 6-OHDA-lesioned rats, however, the same acoustic prepulse facilitated trigeminal reflex blinks but inhibited acoustic reflex blinks. The magnitude of prepulse modification correlated with reflex excitability. Humans exhibited the same pattern of prepulse modification. An acoustic prepulse facilitated the trigeminal reflex blinks of subjects with hyperexcitable trigeminal reflex blinks caused by Parkinson's disease. The same prepulse inhibited trigeminal reflex blinks of age-matched control subjects. Prepulse modification also correlated with trigeminal reflex blink excitability. These data show that reflex modification by a prepulse reflects the intrinsic characteristics of the reflex circuit rather than an external adjustment of the reflex circuit by the prepulse.

  2. The Fontana paradoxical reflex?

    Science.gov (United States)

    Lavorini, Federico; Fontana, Giovanni; Chellini, Elisa; Magni, Chiara; Pistolesi, Massimo; Widdicombe, John

    2011-09-01

    This commentary describes the "deflation cough" caused by deep lung deflations. Deflation cough is a paradoxical reflex similar to that described by Henry Head in 1889 for lung inflations that probably is mediated by the same sensors and afferent fibers in the lungs and activated by gastroesophageal reflux. We discuss how this reflex must be self-limiting, the general role of paradoxical reflexes in the body, and the possible clinical significance of deflation cough.

  3. The spinal reflex cannot be perceptually separated from voluntary movements.

    Science.gov (United States)

    Ghosh, Arko; Haggard, Patrick

    2014-01-01

    , the presence of voluntary movement significantly impairs reflex perception. We suggest that perceptual separation between voluntary and reflex movement is poor at best. Our results imply that the brain has no clear marker for perceptually separating voluntary and involuntary movement. Attribution of body movement to voluntary or involuntary motor commands is surprisingly poor when both are present.

  4. Cruciate ligament reflexes

    DEFF Research Database (Denmark)

    Krogsgaard, Michael R; Dyhre-Poulsen, Poul; Fischer-Rasmussen, Torsten

    2002-01-01

    The idea of muscular reflexes elicited from sensory nerves of the cruciate ligaments is more than 100 years old, but the existence of such reflexes has not been proven until the recent two decades. First in animal experiments, a muscular excitation could be elicited in the hamstrings when the ant...

  5. Reflexivity in qualitative research

    DEFF Research Database (Denmark)

    Evans, Adam Brian; Nistrup, Anne; Henderson, Hannah

    2017-01-01

    There has been something of a “reflexive shift” in sociological research. Sociological researchers are increasingly encouraged to be “present” within their work, and to recognize their own role in structuring the entire research process. One way to achieve this is through engagement in reflexive...... practice, that is, to reflect on our own values, beliefs, and biographies. It can be difficult to know exactly how a researcher should engage in these practices, however. Here, we discuss our reflexive practice in two case studies, both which utilized the same figurational theoretical framework...... Kingdom. Reflexive practice in both studies was affected by researcher biographies and by study design. In Study 1, both researchers were reasonably detached from the study context, the theoretical framework was in place from the very beginning, and reflexive practice was embedded in the study design...

  6. Is perception of self-motion speed a necessary condition for intercepting a moving target while walking?

    Science.gov (United States)

    Morice, Antoine H P; Wallet, Grégory; Montagne, Gilles

    2014-04-30

    While it has been shown that the Global Optic Flow Rate (GOFR) is used in the control of self-motion speed, this study examined its relevance in the control of interceptive actions while walking. We asked participants to intercept approaching targets by adjusting their walking speed in a virtual environment, and predicted that the influence of the GOFR depended on their interception strategy. Indeed, unlike the Constant Bearing Angle (CBA), the Modified Required Velocity (MRV) strategy relies on the perception of self-displacement speed. On the other hand, the CBA strategy involves specific speed adjustments depending on the curvature of the target's trajectory, whereas the MRV does not. We hypothesized that one strategy is selected among the two depending on the informational content of the environment. We thus manipulated the curvature and display of the target's trajectory, and the relationship between physical walking speed and the GOFR (through eye height manipulations). Our results showed that when the target trajectory was not displayed, walking speed profiles were affected by curvature manipulations. Otherwise, walking speed profiles were less affected by curvature manipulations and were affected by the GOFR manipulations. Taken together, these results show that the use of the GOFR for intercepting a moving target while walking depends on the informational content of the environment. Finally we discuss the complementary roles of these two perceptual-motor strategies.

  7. Etnography and Reflexivity

    Directory of Open Access Journals (Sweden)

    Mario Cardano

    2014-01-01

    Full Text Available This essay deals with a relevant and controversial topic – objectivity in ethnographic research. More specifically, I would like to examine how reflexive procedures, more precisely “reflexive account”, can increase the robustness of results gained through an ethnographic research. The essay is organized in five parts. I will start by giving a preliminary definition of the two key concepts which are at the center of the analysis – objectivity and reflexivity. I will then give a brief description of the epistemological framework in which the proposed conceptions of objectivity and reflexivity are located. Thirdly, I move on to consider the epistemic status of ethnographic research, and will emphasize that ethnographies are not just “theory-laden”, as many writers have stated, but also “praxis” or “procedure laden”. In other words, I will stress that it is not only theories which are inevitably embedded in research, influencing how observations can be made; much the same can also be said of the concrete research practices which contribute to determine the experience of the ethnographer and its representation in a text. Fourthly, I will discuss why it is useful to employ reflexive practices, and then immediately afterwards will illustrate the ways in which reflexive descriptions can contribute to greater objectivity of ethnographic accounts. In conclusion, I will discuss a number of objections which have been raised against this use of reflexivity.

  8. On Reflexive Data Models

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, S.

    2000-08-20

    An information system is reflexive if it stores a description of its current structure in the body of stored information and is acting on the base of this information. A data model is reflexive, if its language is meta-closed and can be used to build such a system. The need for reflexive data models in new areas of information technology applications is argued. An attempt to express basic notions related to information systems is made in the case when the system supports and uses meta-closed representation of the data.

  9. Effect of pictorial depth cues, binocular disparity cues and motion parallax depth cues on lightness perception in three-dimensional virtual scenes.

    Directory of Open Access Journals (Sweden)

    Michiteru Kitazaki

    Full Text Available BACKGROUND: Surface lightness perception is affected by scene interpretation. There is some experimental evidence that perceived lightness under bi-ocular viewing conditions is different from perceived lightness in actual scenes but there are also reports that viewing conditions have little or no effect on perceived color. We investigated how mixes of depth cues affect perception of lightness in three-dimensional rendered scenes containing strong gradients of illumination in depth. METHODOLOGY/PRINCIPAL FINDINGS: Observers viewed a virtual room (4 m width x 5 m height x 17.5 m depth with checkerboard walls and floor. In four conditions, the room was presented with or without binocular disparity (BD depth cues and with or without motion parallax (MP depth cues. In all conditions, observers were asked to adjust the luminance of a comparison surface to match the lightness of test surfaces placed at seven different depths (8.5-17.5 m in the scene. We estimated lightness versus depth profiles in all four depth cue conditions. Even when observers had only pictorial depth cues (no MP, no BD, they partially but significantly discounted the illumination gradient in judging lightness. Adding either MP or BD led to significantly greater discounting and both cues together produced the greatest discounting. The effects of MP and BD were approximately additive. BD had greater influence at near distances than far. CONCLUSIONS/SIGNIFICANCE: These results suggest the surface lightness perception is modulated by three-dimensional perception/interpretation using pictorial, binocular-disparity, and motion-parallax cues additively. We propose a two-stage (2D and 3D processing model for lightness perception.

  10. Visual Motion Perception

    Science.gov (United States)

    1991-08-15

    involving voting rules for com- projection of dots on the surface ofa smooth 3D KDE and opne flo-lI 861 shape under rotary oscillation . In one condition the...Satms 196611974: Sperdn; & Doshar. All subjects remnembser the shape of the oscillating object, but 1955). Indeed the ilicieniey of i:rfoc maonue...asl- A~cke~. A 649?. smocin in th fene donain. XASA Tetket,!SlUn i9~. (24j7 eosL-gorte f.eon loo- w=1-e 44312: j. vdloe.y R.-’--t C (2930)> Me tiN--2~y

  11. Long-Term Effects of Serial Anodal tDCS on Motion Perception in Subjects with Occipital Stroke Measured in the Unaffected Visual Hemifield

    Science.gov (United States)

    Olma, M. C.; Dargie, R. A.; Behrens, J. R.; Kraft, A.; Irlbacher, K.; Fahle, M.; Brandt, S. A.

    2013-01-01

    Transcranial direct current stimulation (tDCS) is a novel neuromodulatory tool that has seen early transition to clinical trials, although the high variability of these findings necessitates further studies in clinically relevant populations. The majority of evidence into effects of repeated tDCS is based on research in the human motor system, but it is unclear whether the long-term effects of serial tDCS are motor-specific or transferable to other brain areas. This study aimed to examine whether serial anodal tDCS over the visual cortex can exogenously induce long-term neuroplastic changes in the visual cortex. However, when the visual cortex is affected by a cortical lesion, up-regulated endogenous neuroplastic adaptation processes may alter the susceptibility to tDCS. To this end, motion perception was investigated in the unaffected hemifield of subjects with unilateral visual cortex lesions. Twelve subjects with occipital ischemic lesions participated in a within-subject, sham-controlled, double-blind study. MRI-registered sham or anodal tDCS (1.5 mA, 20 min) was applied on five consecutive days over the visual cortex. Motion perception was tested before and after stimulation sessions and at 14- and 28-day follow-up. After a 16-day interval an identical study block with the other stimulation condition (anodal or sham tDCS) followed. Serial anodal tDCS over the visual cortex resulted in an improvement in motion perception, a function attributed to MT/V5. This effect was still measurable at 14- and 28-day follow-up measurements. Thus, this may represent evidence for long-term tDCS-induced plasticity and has implications for the design of studies examining the time course of tDCS effects in both the visual and motor systems. PMID:23805097

  12. Long-term effects of serial anodal tDCS on motion perception in subjects with occipital stroke measured in the unaffected visual hemifield

    Directory of Open Access Journals (Sweden)

    Manuel C Olma

    2013-06-01

    Full Text Available Transcranial direct current stimulation (tDCS is a novel neuromodulatory tool that has seen early transition to clinical trials, although the high variability of these findings necessitates further studies in clincally-relevant populations. The majority of evidence into effects of repeated tDCS is based on research in the human motor system, but it is unclear whether the long-term effects of serial tDCS are motor-specific or transferable to other brain areas. This study aimed to examine whether serial anodal tDCS over the visual cortex can exogenously induce long-term neuroplastic changes in the visual cortex. However, when the visual cortex is affected by a cortical lesion, up-regulated endogenous neuroplastic adaptation processes may alter the susceptibility to tDCS. To this end, motion perception was investigated in the unaffected hemifield of subjects with unilateral visual cortex lesions. Twelve subjects with occipital ischaemic lesions participated in a within-subject, sham-controlled, double-blind study. MRI-registered sham or anodal tDCS (1.5 mA, 20 minutes was applied on five consecutive days over the visual cortex. Motion perception was tested before and after stimulation sessions and at 14- and 28-day follow-up. After a 16-day interval an identical study block with the other stimulation condition (anodal or sham tDCS followed. Serial anodal tDCS over the visual cortex resulted in an improvement in motion perception, a function attributed to MT/V5. This effect was still measurable at 14- and 28-day follow-up measurements. Thus, this may represent evidence for long-term tDCS-induced plasticity and has implications for the design of studies examining the time course of tDCS effects in both the visual and motor systems.

  13. Absent activation in medial prefrontal cortex and temporoparietal junction but not superior temporal sulcus during the perception of biological motion in schizophrenia: a functional MRI study

    Directory of Open Access Journals (Sweden)

    Hashimoto N

    2014-11-01

    Full Text Available Naoki Hashimoto,1,2 Atsuhito Toyomaki,1 Masahiro Hirai,3 Tamaki Miyamoto,1 Hisashi Narita,1 Ryo Okubo,1 Ichiro Kusumi1 1Department of Psychiatry, Graduate School of Medicine, Hokkaido University, Sapporo, Japan; 2Child and Adolescent Psychiatry, Department of Psychiatry, University of California, San Francisco, CA, USA; 3Center for Development of Advanced Medical Technology, Jichi Medical University, Yakushiji, Shimotsuke, Tochigi, Japan Background: Patients with schizophrenia show disturbances in both visual perception and social cognition. Perception of biological motion (BM is a higher-level visual process, and is known to be associated with social cognition. BM induces activation in the “social brain network”, including the superior temporal sulcus (STS. Although deficits in the detection of BM and atypical activation in the STS have been reported in patients with schizophrenia, it remains unclear whether other nodes of the “social brain network” are also atypical in patients with schizophrenia.Purpose: We aimed to explore whether brain regions other than STS were involved during BM perception in patients with schizophrenia, using functional magnetic resonance imaging (fMRI.Methods and patients: Seventeen patients with schizophrenia, and 17 age- and sex- matched healthy controls, underwent fMRI scanning during a one-back visual task, containing three experimental conditions: (1 BM, (2 scrambled motion (SM, and (3 static condition. We used one-sample t-tests to examine neural responses selective to BM versus SM within each group, and two-sample t-tests to directly compare neural patterns to BM versus SM in schizophrenics versus controls.Results: We found significant activation in the STS region when BM was contrasted with SM in both groups, with no significant difference between groups. On the contrary, significant activation in the medial prefrontal cortex (MPFC and bilateral temporoparietal junction (TPJ was found only in the

  14. Role of orientation reference selection in motion sickness, supplement 2S

    Science.gov (United States)

    Peterka, Robert J.; Black, F. Owen

    1987-01-01

    Previous experiments with moving platform posturography have shown that different people have varying abilities to resolve conflicts among vestibular, visual, and proprioceptive sensory signals. The conceptual basis of the present proposal hinges on the similarities between the space motion sickness problem and the sensory orientation reference selection problems associated with benign paroxysmal positional vertigo (BPPV) syndrome. These similarities include both etiology related to abnormal vertical canal-otolith function, and motion sickness initiating events provoked by pitch and roll head movements. The objectives are to explore and quantify the orientation reference selection abilities of subjects and the relation of this selection to motion sickness in humans. The overall objectives are to determine: if motion sickness susceptibility is related to sensory orientation reference selection abilities of subjects; if abnormal vertical canal-otolith function is the source of abnormal posture control strategies and if it can be quantified by vestibular and oculomotor reflex measurements, and if it can be quantified by vestibular and oculomotor reflex measurements; and quantifiable measures of perception of vestibular and visual motion cues can be related to motion sickness susceptibility and to orientation reference selection ability.

  15. Corneomandibular reflex: Anatomical basis

    Directory of Open Access Journals (Sweden)

    Michele Pistacchi

    2015-01-01

    Full Text Available Corneomandibular reflex is a pathological phenomenon evident in cases of severe brainstem damage. It is considered to be a pathological exteroceptive reflex, associated with precentro bulbar tract lesions. The sign is useful in distinguishing central neurological injuries to metabolic disorders in acutely comatose patients, localizing lesions to the upper brainstem area, determining the depth of coma and its evolution, providing evidence of uncal or transtentorial herniation in acute cerebral hemisphere lesions, and it is a marker of supraspinal level impairment in amyotrophic lateral sclerosis and multiple sclerosis. This sign was evident in a patient with severe brain damage. We discuss the literature findings and its relevance in prognosis establishment.

  16. A Visual Perception Algorithm for Human Motion by a Kinect%利用Kinect的人体动作视觉感知算法

    Institute of Scientific and Technical Information of China (English)

    朱特浩; 赵群飞; 夏泽洋

    2014-01-01

    A visual perception algorithm of human motion for humanoid robot is proposed to improve the precision of the motion data captured from a Kinect. Firstly, the positions of the joints are transformed into the angles according to the inverse kinematics equations. Secondly, the long-time motion is segmented into episodes automatically based on the change of the angular velocity and acceleration, and then RVM (relevant vector machine) is utilized for estimating the angle trajectories with high accuracy. Finally, the spatial consistence, temporal consistence and smoothness of the angle trajectories are given to evaluate the algorithm, and a motion data series processed by the algorithm is implemented on a NAO robot platform. The experimental results indicate that the proposed algorithm effectively improves the spatial and temporal consistence of the motion perception and the smoothness of the trajectory, which provides a foundation for high-precision motion imitation.%提出了一种面向类人机器人的人体动作视觉感知算法,提高了利用Kinect作为视觉输入设备捕捉到的人体动作数据的精度。首先,通过逆运动学方程将捕捉到的关节位移信息转换成角度信息。然后,以角速度和角加速度的变化为依据,将长时间的运动自动分割成独立片段,并用相关向量机原理估计出高精度的角度轨迹。最后,用角度轨迹的空间相似性、时间相似性、平滑度等指标对该算法进行了评估,并在NAO机器人平台上对算法处理后的动作进行了实验验证。实验结果表明,该算法有效提高了动作感知的时空相似性和轨迹平滑度,为高精度的动作模仿奠定了基础。

  17. The Babinski reflex.

    Science.gov (United States)

    van Gijn, J

    1995-11-01

    The plantar response is a reflex that involves not only the toes, but all muscles that shorten the leg. In the newborn the synergy is brisk, involving all flexor muscles of the leg; these include the toe 'extensors', which also shorten the leg on contraction and therefore are flexors in a physiological sense. As the nervous system matures and the pyramidal tract gains more control over spinal motoneurones the flexion synergy becomes less brisk, and the toe 'extensors' are no longer part of it. The toes then often go down instead of up, as a result of a segmental reflex involving the small foot muscles and the overlying skin, comparable to the abdominal reflexes. With lesions of the pyramidal system, structural or functional, this segmental, downward response of the toes disappears, the flexion synergy may become disinhibited and the extensor hallucis longus muscle is again recruited into the flexion reflex of the leg: the sign of Babinski. A true Babinski sign denotes dysfunction of the pyramidal tract, and should be clearly distinguished from upgoing toes that do not belong to the flexion synergy of the leg. Correct interpretation of the plantar response depends only to a minor degree on the method or site of stimulation of the foot. It is therefore most important to assess the response in the entire leg.

  18. Reflexivity and social justice

    DEFF Research Database (Denmark)

    Maksimovic, Tijana; Jakobsen, Helle Nordentoft

    2017-01-01

    Career practitioners’ reflexive understanding of their professional role as change agents in career guidance and counselling practices has a major impact on how social justice can be achieved. This entitles an awareness of the way in which guidance and counselling practices are embedded in the co...

  19. Identification of Spinal Reflexes

    NARCIS (Netherlands)

    De Vlugt, E.

    2004-01-01

    Visco-elasticity of joints is important for the maintenance of the human body posture and can in two manners be regulated. By means of cocontraction of antagonistic muscle groups and by neural reflexive feedback of muscle length and muscle strength, measured both by means of sensors in the muscles.

  20. Studies of the horizontal vestibulo-ocular reflex in spaceflight

    Science.gov (United States)

    Thornton, William E.; Uri, John J.; Moore, Tom; Pool, Sam

    1989-01-01

    Changes in the vestibulo-ocular reflex (VOR) during space flight have been suspected of contributing to space motion sickness. The horizontal VOR was studied in nine subjects on two space shuttle missions. Active unpaced head oscillation at 0.3 Hz was used as the stimulus to examine the gain and phase of the VOR with and without visual input, as well as the visual suppression of the reflex. No statistically significant changes were noted inflight in the gains or phase shifts of the VOR during any test condition, or between space motion sickness susceptible and nonsusceptible populations. Although VOR suppression was unaffected by spaceflight, the space motion sickness-susceptible group tended to exhibit greater error in the suppression than the nonsusceptible group. It is concluded that at this stimulus frequency, VOR gain is unaffected by space-flight, and any minor individual changes do not seem to contribute to space motion sickness.

  1. Spinal reflexes in brain death.

    Science.gov (United States)

    Beckmann, Yesim; Çiftçi, Yeliz; Incesu, Tülay Kurt; Seçil, Yaprak; Akhan, Galip

    2014-12-01

    Spontaneous and reflex movements have been described in brain death and these unusual movements might cause uncertainties in diagnosis. In this study we evaluated the presence of spinal reflexes in patients who fulfilled the criteria for brain death. Thirty-two (22 %) of 144 patients presented unexpected motor movements spontaneously or during examinations. These patients exhibited the following signs: undulating toe, increased deep tendon reflexes, plantar responses, Lazarus sign, flexion-withdrawal reflex, facial myokymia, neck-arm flexion, finger jerks and fasciculations. In comparison, there were no significant differences in age, sex, etiology of brain death and hemodynamic laboratory findings in patients with and without reflex motor movement. Spinal reflexes should be well recognized by physicians and it should be born in mind that brain death can be determined in the presence of spinal reflexes.

  2. Mentalis muscle related reflexes.

    Science.gov (United States)

    Gündüz, Ayşegül; Uyanık, Özlem; Ertürk, Özdem; Sohtaoğlu, Melis; Kızıltan, Meral Erdemir

    2016-05-01

    The mentalis muscle (MM) arises from the incisive fossa of the mandible, raises and protrudes the lower lip. Here, we aim to characterize responses obtained from MM by supraorbital and median electrical as well as auditory stimuli in a group of 16 healthy volunteers who did not have clinical palmomental reflex. Reflex activities were recorded from the MM and orbicularis oculi (O.oc) after supraorbital and median electrical as well as auditory stimuli. Response rates over MM were consistent after each stimulus, however, mean latencies of MM response were longer than O.oc responses by all stimulation modalities. Shapes and amplitudes of responses from O.oc and MM were similar. Based on our findings, we may say that MM motoneurons have connections with trigeminal, vestibulocochlear and lemniscal pathways similar to other facial muscles and electrophysiological recording of MM responses after electrical and auditory stimulation is possible in healthy subjects.

  3. Reflex epilepsy: a review

    Directory of Open Access Journals (Sweden)

    Karim Nikkhah

    2017-01-01

    Full Text Available Interesting phenomena of reflex epileptic syndromes are characterized by epileptic seizures each one induced by specific stimulus with a variety of types. Simple triggers, which lead to seizures within seconds, are of sensory type (most commonly visual, most rarely tactile or proprioceptive stimuli. Complex triggers, which are mostly of cognitive type such as praxis, reading, talking, and music, usually induce the epileptic event within minutes. It should differ from what most epileptic patients report as provocative precipitants for seizures (such as emotional stress, fatigue, fever, sleep deprivation, alcohol, and menstrual cycle. The identification of a specific trigger is not only important for patients or their parents to avoid seizures, but also it might help neurologists to choose the most effective antiepileptic drug for each case. In addition, research in this area may possibly reveal some underlying pathophysiology of epileptic phenomena in the brain.In this review, we briefly introduce reported reflex epileptic seizures, their clinical features and management.

  4. Vehicle Perception and Motion State Forecasting Technology%车辆姿态感知与运动状态预测技术

    Institute of Scientific and Technical Information of China (English)

    葛如海; 管军; 虞小波; 石存杰

    2013-01-01

    Currently most automotive active safety warning system which has been put into use is expensive,but stays in the vehicle motion posture monitoring and alarm functions,lacking of further prediction of the vehicle' s own motion attitude for future time.Considering these shortcomings,launching vehicle motion prediction and predicting vehicle motion posture for future time in advance,can play a very important role to improve the vehicle' s active safety and reduce road traffic accidents.The latest 6-axis Motion Processing Unit (MPU) MPU-6050 can realize vehicle posture parameters online perception.The Kalman filter is designed,through signal fusion processing we can get the optimal estimate of the vehicle motion posture parameters,using multi-level recursive model to carry out the prediction research.Finally,taking vertical speed,roll angle and yaw angle for example,we carry on perception and prediction.A good prediction effect is got by road test,which shows the feasibility and exploratory of the vehicle perception and prediction technology.%目前大多数已投入使用的汽车主动安全预警系统价格昂贵,而且停留在对汽车运动姿态的监测和报警功能上,缺乏对汽车未来时刻自身运动姿态作进一步预测.针对这些不足性,本文进行汽车运动姿态在线预测的研究,提前预测汽车未来时刻可能的行驶运行状态,对提高汽车的主动安全性,减少道路交通事故将起到十分重要的作用.采用最新的6轴运动处理组件MPU-6050实现汽车运动姿态参数的在线感知,设计卡尔曼滤波器,通过信号融合处理,获取汽车运动姿态参数的最优估计值,采用多层递阶模型来开展汽车运动姿态参数的预测.最后以纵向车速、侧倾角和横摆角为例开展感知与预测,进行实车道路试验,取得了很好的预测效果.实验结果表明所开展的汽车感知与预测技术的可行性和探索性.

  5. Neurophysiological methods for the assessment of spasticity: the Hoffmann reflex, the tendon reflex, and the stretch reflex

    NARCIS (Netherlands)

    Voerman, Gerlienke; Gregoric, M.; Hermens, Hermanus J.

    PURPOSE: To review the literature concerning neurophysiological methods to assess spasticity with respect to mechanisms and methodology, and to describe the three most commonly used methods: the Hoffmann reflex (H-reflex), the Tendon reflex (T-reflex), and the Stretch Reflex (SR). METHOD: A

  6. Effect of sway and yaw motion on perception and control; A multi-simulator, follow-up study

    NARCIS (Netherlands)

    Ellerbroek, J.; Stroosma, O.; Wentink, M.; Groen, E.L.

    2006-01-01

    The three Dutch research institutes NLR, TNO and TU Delft are collaborating to perform a multi-simulator follow-up study aimed at investigating the influence of yaw and translational motion cues in helicopter- and general flight-simulation. In this study, new experimental results will be combined

  7. Adductor T reflex abnormalities in patients with decreased patellar reflexes.

    Science.gov (United States)

    Tataroglu, Cengiz; Deneri, Ersin; Ozkul, Ayca; Sair, Ahmet; Yaycioglu, Soner

    2009-08-01

    The adductor reflex (AR) is a tendon reflex that has various features that differ from other tendon reflexes. This reflex was tested in different disorders presenting with diminished patellar reflexes such as diabetic lumbosacral radiculoplexus neuropathy (DLRPN), L2-L4 radiculopathy, and distal symmetric diabetic neuropathy (diabetic PNP). The AR and crossed-AR (elicited by tapping the contralateral patellar tendon) were recorded using concentric needle electrodes. Additionally, the patellar T reflex (vm-TR) and vastus medialis H reflex (vm-HR) were recorded using surface electrodes. AR was recorded in only one out of eight patients with DLRPN, but it was recorded in 21 out of 22 patients with L2-L4 radiculopathy (95.5%). Of these reflexes, only AR showed prolonged latency in the L2-L4 radiculopathy group. The latencies of AR, vm-TR, and vm-HR were prolonged in patients with diabetic PNP. We conclude that AR can be useful in the differential diagnosis of some lower motor neuron disorders that present with patellar reflex disturbance. Muscle Nerve 40: 264-270, 2009.

  8. Gastric sensitivity and reflexes: basic mechanisms underlying clinical problems.

    Science.gov (United States)

    Azpiroz, Fernando; Feinle-Bisset, Christine; Grundy, David; Tack, Jan

    2014-02-01

    Both reflex and sensory mechanisms control the function of the stomach, and disturbances in these mechanisms may explain the pathophysiology of disorders of gastric function. The objective of this report is to perform a literature-based critical analysis of new, relevant or conflicting information on gastric sensitivity and reflexes, with particular emphasis on the comprehensive integration of basic and clinical research data. The stomach exerts both phasic and tonic muscular (contractile and relaxatory) activity. Gastric tone determines the capacity of the stomach and mediates both gastric accommodation to a meal as well as gastric emptying, by partial relaxation or progressive recontraction, respectively. Perception and reflex afferent pathways from the stomach are activated independently by specific stimuli, suggesting that the terminal nerve endings operate as specialized receptors. Particularly, perception appears to be related to stimulation of tension receptors, while the existence of volume receptors in the stomach is uncertain. Reliable techniques have been developed to measure gastric perception and reflexes both in experimental and clinical conditions, and have facilitated the identification of abnormal responses in patients with gastric disorders. Gastroparesis is characterised by impaired gastric tone and contractility, whereas patients with functional dyspepsia have impaired accommodation, associated with antral distention and increased gastric sensitivity. An integrated view of fragmented knowledge allows the design of pathophysiological models in an attempt to explain disorders of gastric function, and may facilitate the development of mechanistically orientated treatments.

  9. Mechanical Characteristics of Reflex Durign Upright Posture in Paralyzed Subjects

    Science.gov (United States)

    Kim, Yongchul; Youm, Youngil; Lee, Bumsuk; Kim, Youngho; Choi, Hyeonki

    The characteristics of flexor reflexes have been investigated in the previous studies with human subjects who were seated or supine position. However, researchers did not describe how the spinal circuits are used in different hip angles for paralyzed subjects, such as the standing position with walker or cane. In upright posture the compatibility between a flexor reflex of leg and body balance is a special problem for lower limb injured subjects. Therefore, the purpose of this study was to investigate the effects of hip angle change on the flexor reflex evoked in standing paralyzed subjects supported by walker. In this study, six spinal cord injured and four stroke subjects were recruited through the inpatient physical therapy clinics of Korea national rehabilitation hospital. A single axis electronic goniometer was mounted on the lateral side of the hip joint of the impaired limb to record movements in the sagittal plane at this joint. The electronic goniometer was connected to a data acquisition system, through amplifiers to a computer. Since subject' posture influenced characteristics of the flexion reflex response, the subjects were supported in an upright posture by the help of parallelogram walder. Two series of tests were performed on each leg. The first series of the tests investigated the influence of hip angle during stationary standing posture on flexion reflex response. The hip angle was adjusted by the foot plate. The second examined the effect of the voluntary action of subject on swing motion during the gait. The electrically induced flexion reflex simultaneously produced the flexion of the hip, knee and dorsiflexion of the ankle enabling the swing phase of walking. Form the experimental results we observed that the reflex response of hip joint was largerwith the hip in the extended position than in the flexed position during standing posture. Under voluntary movement on flexion reflex during gaint, the peak hip angle induced by stimulation was

  10. Phase-Based Binocular Perception of Motion in Depth: Cortical-Like Operators and Analog VLSI Architectures

    Science.gov (United States)

    Sabatini, Silvio P.; Solari, Fabio; Cavalleri, Paolo; Bisio, Giacomo Mario

    2003-12-01

    We present a cortical-like strategy to obtain reliable estimates of the motions of objects in a scene toward/away from the observer (motion in depth), from local measurements of binocular parameters derived from direct comparison of the results of monocular spatiotemporal filtering operations performed on stereo image pairs. This approach is suitable for a hardware implementation, in which such parameters can be gained via a feedforward computation (i.e., collection, comparison, and punctual operations) on the outputs of the nodes of recurrent VLSI lattice networks, performing local computations. These networks act as efficient computational structures for embedded analog filtering operations in smart vision sensors. Extensive simulations on both synthetic and real-world image sequences prove the validity of the approach that allows to gain high-level information about the 3D structure of the scene, directly from sensorial data, without resorting to explicit scene reconstruction.

  11. Phase-Based Binocular Perception of Motion in Depth: Cortical-Like Operators and Analog VLSI Architectures

    Directory of Open Access Journals (Sweden)

    Silvio P. Sabatini

    2003-06-01

    Full Text Available We present a cortical-like strategy to obtain reliable estimates of the motions of objects in a scene toward/away from the observer (motion in depth, from local measurements of binocular parameters derived from direct comparison of the results of monocular spatiotemporal filtering operations performed on stereo image pairs. This approach is suitable for a hardware implementation, in which such parameters can be gained via a feedforward computation (i.e., collection, comparison, and punctual operations on the outputs of the nodes of recurrent VLSI lattice networks, performing local computations. These networks act as efficient computational structures for embedded analog filtering operations in smart vision sensors. Extensive simulations on both synthetic and real-world image sequences prove the validity of the approach that allows to gain high-level information about the 3D structure of the scene, directly from sensorial data, without resorting to explicit scene reconstruction.

  12. Perception of musical tension in short chord sequences: the influence of harmonic function, sensory dissonance, horizontal motion, and musical training.

    Science.gov (United States)

    Bigand, E; Parncutt, R; Lerdahl, F

    1996-01-01

    This study investigates the effect of four variables (tonal hierarchies, sensory chordal consonance, horizontal motion, and musical training) on perceived musical tension. Participants were asked to evaluate the tension created by a chord X in sequences of three chords [C major-->X-->C major] in a C major context key. The X chords could be major or minor triads major-minor seventh, or minor seventh chords built on the 12 notes of the chromatic scale. The data were compared with Krumhansl's (1990) harmonic hierarchy and with predictions of Lerdahl's (1988) cognitive theory, Hutchinson and Knopoff's (1978) and Parncutt's (1989) sensory-psychoacoustical theories, and the model of horizontal motion defined in the paper. As a main outcome, it appears that judgments of tension arose from a convergence of several cognitive and psychoacoustics influences, whose relative importance varies, depending on musical training.

  13. Too Busy for Reflexivity?

    DEFF Research Database (Denmark)

    Ratner, Helene

    highlighted non-symmetric relationships between observer and observed and accused the academic text of enacting a realist genre, concealing the relativism entailed in textual production (Clifford and Marcus 1986, Woolgar 1988, Ashmore 1989). On the other hand, the reflexivity program produced fears...... of a “corrosive relativism in which everything is but a more or less clever expression of opinion” (Geertz 1988:2, 3) and it has suffered the little flattering accusations of piling "layer upon layer of self-consciousness to no avail" (Latour 1988:170) with little “interest [for] … theoretically ambitious...

  14. [Laryngeal and larynx-associated reflexes].

    Science.gov (United States)

    Ptok, M; Kühn, D; Miller, S; Jungheim, M; Schroeter, S

    2016-06-01

    The laryngeal adductor reflex and the pharyngoglottal closure reflex protect the trachea and lower respiratory tract against the entrance of foreign material. The laryngeal expiration reflex and the cough reflex serve to propel foreign material, which has penetrated in the cranial direction. The inspiration reflex, the sniff reflex, and the swallowing reflex are further larynx-associated reflexes. In patients with dysphagia the laryngeal adductor reflex can be clinically tested with air pulses. The water swallow test serves to show the integrity of the cough reflex. The sniff reflex is useful to test the abduction function of the vocal folds. Future studies should address laryngeal reflexes more specifically, both for a better understanding of these life-supporting mechanisms and to improve diagnostic procedures in patients with impaired laryngeal function.

  15. Patterning of somatosympathetic reflexes

    Science.gov (United States)

    Kerman, I. A.; Yates, B. J.

    1999-01-01

    In a previous study, we reported that vestibular nerve stimulation in the cat elicits a specific pattern of sympathetic nerve activation, such that responses are particularly large in the renal nerve. This patterning of vestibulosympathetic reflexes was the same in anesthetized and decerebrate preparations. In the present study, we report that inputs from skin and muscle also elicit a specific patterning of sympathetic outflow, which is distinct from that produced by vestibular stimulation. Renal, superior mesenteric, and lumbar colonic nerves respond most strongly to forelimb and hindlimb nerve stimulation (approximately 60% of maximal nerve activation), whereas external carotid and hypogastric nerves were least sensitive to these inputs (approximately 20% of maximal nerve activation). In contrast to vestibulosympathetic reflexes, the expression of responses to skin and muscle afferent activation differs in decerebrate and anesthetized animals. In baroreceptor-intact animals, somatosympathetic responses were strongly attenuated (to 150 mmHg. These findings demonstrate that different types of somatic inputs elicit specific patterns of sympathetic nerve activation, presumably generated through distinct neural circuits.

  16. Proprioceptive reflexes and neurological disorders

    NARCIS (Netherlands)

    Schouten, A.C.

    2004-01-01

    Proprioceptive reflexes play an important role during the control of movement and posture. Disturbed modulation of proprioceptive reflexes is often suggested as the cause for the motoric features present in neurological disorders. In this thesis methods are developed and evaluated to quantify propri

  17. Reflexive Aero Structures for Enhanced Survivability Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Cornerstone Research Group Inc. (CRG) proposes to develop an advanced reflexive structure system to increase the survivability of aerostructures. This reflexive...

  18. Acoustic reflex and general anaesthesia.

    Science.gov (United States)

    Farkas, Z

    1983-01-01

    Infant and small children are not always able to cooperate in impedance measurements. For this reason it was decided, -in special cases, -to perform acoustic reflex examination under general anaesthesia. The first report on stapedius reflex and general anaesthesia was published by Mink et al. in 1981. Under the effect of Tiobutabarbital, Propanidid and Diazepam there is no reflex response. Acoustic reflex can be elicited with Ketamin-hydrochlorid and Alphaxalone-alphadolone acetate narcosis. The reflex threshold remains unchanged and the amplitude of muscle contraction is somewhat increased. The method was used: 1. to assess the type and degree of hearing loss in children with cleft palate and/or lip prior to surgery. 2. to exclude neuromuscular disorders with indication of pharyngoplasties. 3. to quantify hearing level in children--mostly multiply handicapped--with retarded speech development. The results of Behavioral Observation and Impedance Audiometry are discussed and evaluated.

  19. [Reflex seizures, cinema and television].

    Science.gov (United States)

    Olivares-Romero, Jesús

    2015-12-16

    In movies and television series are few references to seizures or reflex epilepsy even though in real life are an important subgroup of total epileptic syndromes. It has performed a search on the topic, identified 25 films in which they appear reflex seizures. Most seizures observed are tonic-clonic and visual stimuli are the most numerous, corresponding all with flashing lights. The emotions are the main stimuli in higher level processes. In most cases it is not possible to know if a character suffers a reflex epilepsy or suffer reflex seizures in the context of another epileptic syndrome. The main conclusion is that, in the movies, the reflex seizures are merely a visual reinforcing and anecdotal element without significant influence on the plot.

  20. The vestibulosympathetic reflex in humans: neural interactions between cardiovascular reflexes

    Science.gov (United States)

    Ray, Chester A.; Monahan, Kevin D.

    2002-01-01

    1. Over the past 5 years, there has been emerging evidence that the vestibular system regulates sympathetic nerve activity in humans. We have studied this issue in humans by using head-down rotation (HDR) in the prone position. 2. These studies have clearly demonstrated increases in muscle sympathetic nerve activity (MSNA) and calf vascular resistance during HDR. These responses are mediated by engagement of the otolith organs and not the semicircular canals. 3. However, differential activation of sympathetic nerve activity has been observed during HDR. Unlike MSNA, skin sympathetic nerve activity does not increase with HDR. 4. Examination of the vestibulosympathetic reflex with other cardiovascular reflexes (i.e. barorereflexes and skeletal muscle reflexes) has shown an additive interaction for MSNA. 5. The additive interaction between the baroreflexes and vestibulosympathetic reflex suggests that the vestibular system may assist in defending against orthostatic challenges in humans by elevating MSNA beyond that of the baroreflexes. 6. In addition, the further increase in MSNA via otolith stimulation during isometric handgrip, when arterial pressure is elevated markedly, indicates that the vestibulosympathetic reflex is a powerful activator of MSNA and may contribute to blood pressure and flow regulation during dynamic exercise. 7. Future studies will help evaluate the importance of the vestibulosympathetic reflex in clinical conditions associated with orthostatic hypotension.

  1. Oculocardiac reflex during strabismus surgery

    Directory of Open Access Journals (Sweden)

    Mehryar Taghavi Gilani

    2016-12-01

    Full Text Available The activation of oculucardiac reflex (OCR is common during the strabismus surgeries. OCR is known as a trigemino-vagal reflex, which leads to the various side effects including bradycardia, tachycardia, arrhythmia, or in some cases cardiac arrest. This reflex could be activated during intraorbital injections, hematomas, and mechanical stimulation of eyeball and extraocular muscles surgeries. The incidence of OCR varies in a wide range, from 14% to 90%, that depends on anesthetic strategy and drug used for the surgery. The efficacy of various anticholinergic and anesthetic agents on declining the OCR reflex has been evaluated in different studies, especially in children. Although the detection of OCR goes back to 1908, its exact effect is not well recognized during strabismus surgery. In this review, we aimed to summarize the studies investigated the efficacy and potential of various anesthetic medications on inhibiting the OCR in children undergoing strabismus surgery.

  2. Management of Reflex Anoxic Seizures

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2013-10-01

    Full Text Available Investigators at the Roald Dahl EEG Unit, Alder Hey Children’s NHS Foundation, Liverpool, UK, review the definition, pathophysiology, clinical presentation, and management of reflex anoxic seizures (RAS in children.

  3. SYSTEM REFLEXIVE STRATEGIC MARKETING MANAGEMENT

    Directory of Open Access Journals (Sweden)

    A. Dligach

    2013-10-01

    Full Text Available This article reviews the System Reflexive paradigm of strategic marketing management, being based on the alignment of strategic economic interests of stakeholders, specifically, enterprise owners and hired managers, and consumers. The essence of marketing concept of management comes under review, along with the strategic management approaches to business, buildup and alignment of economic interests of business stakeholders. A roadmap for resolving the problems of modern marketing is proposed through the adoption of System Reflexive marketing theory.

  4. SYSTEM REFLEXIVE STRATEGIC MARKETING MANAGEMENT

    Directory of Open Access Journals (Sweden)

    Andrii A. DLIGACH

    2012-07-01

    Full Text Available This article reviews the System Reflexive paradigm of strategic marketing management, being based on the alignment of strategic economic interests of stakeholders, specifically, enterprise owners and hired managers, and consumers. The essence of marketing concept of management comes under review, along with the strategic management approaches to business, buildup and alignment of economic interests of business stakeholders. A roadmap for resolving the problems of modern marketing is proposed through the adoption of System Reflexive marketing theory.

  5. 帕金森病患者生物运动感知能力研究%Biological motion perception in patients with Parkinson's disease

    Institute of Scientific and Technical Information of China (English)

    操瑞花; 叶星; 田仰华; 胡盼盼; 陈先文; 汪凯

    2014-01-01

    Objective To explore the biological motion perception in Parkinson's disease (PD).Methods 45 individuals with idiopathic PD were compared with 45 matched healthy controls (HCs) using a duration discrimination task.Results The point of subjective equality(PSE) was negative value (-0.27±0.17) for health controls (HCs),and there was significant difference compared with "PSE =0" by one sample t test (t=10.96,P< 0.01).Compared with HCs,the PSE for PD patients (-0.14±0.30) significantly decreased (t=2.63,P=0.01).When further dividing PD into early stages (stage 1-2) and late stages (stage 3-4),significant difference was found between late-stage PD patients(0.02±0.39)and HCs (t=4.07,P=0.008),but not between early-stage PD patients (-0.24±0.14) and HCs (t=0.84,P=0.405).Conclusion There is biological motion perception disorder in PD patients and it is related to the severity of PD.%目的 探讨帕金森病(Parkinson's disease,PD)患者生物运动感知能力.方法 采用时距辨别任务,对45例原发性PD患者和45例正常对照组进行生物运动感知能力测试.结果 正常对照组的主观相等点(point of subjective equality,PSE)为负值(-0.27±0.17),与检验值“0”相比差异有统计学意义(t=10.96,P<0.01).PD患者组的PSE(-0.14±0.30)较正常对照组的PSE值明显减小,差异有统计学意义(t=2.63,P=0.01).PD早期组(H-Y 1-2级)的PSE值(-0.24±0.14)与正常对照组的PSE值之间差异无统计学意义(t=0.84,P=0.405),而PD晚期组(H-Y 3-4级)的PSE(0.02±0.39)负值基本消失,与正常对照组的PSE值之间差异有统计学意义(t=4.07,P=0.008).结论 PD患者存在生物运动感知障碍,且与病情的严重程度相关.

  6. An assessment of the impact of a science outreach program, Science In Motion, on student achievement, teacher efficacy, and teacher perception

    Science.gov (United States)

    Herring, Phillip Allen

    The purpose of the study was to analyze the science outreach program, Science In Motion (SIM), located in Mobile, Alabama. This research investigated what impact the SIM program has on student cognitive functioning and teacher efficacy and also investigated teacher perceptions and attitudes regarding the program. To investigate student cognitive functioning, data were collected from the Mobile County Public School System based upon student performance on Criterion Referenced Tests (CRT's), consisting of the students' average score, percent of students passing the test (students scoring 60 percent or above), and the percent of students who were considered proficient, (students scoring 70 percent or above). The researcher hypothesized that (1) the students of teachers who participate in the SIM program would have statistically significant higher scores on their science CRT's than students of the same teacher prior to the teacher's participation in the SIM program, (2) students of science teachers who participate in the SIM program would have statistically significant higher scores on their science CRT's than students of science teachers who do not participate in the SIM program, and (3) teachers who participate in the SIM program would have a higher efficacy, as measured on the Teachers' Sense of Efficacy Scale developed by Tschnnen-Moran & Hoy (2001), than science teachers who do not participate in the SIM program. Statistical significant differences at the p affected the participating teachers' perspectives towards teaching science, funding of the science laboratory, and high stakes science testing and accountability. A phenomenological qualitative study was performed. The analysis consisted of coding the data and describing the associated themes. The themes were: SIM laboratory exposure Increases student success; SIM reduces teacher stress; SIM provides high quality laboratories for the science classroom; SIM needs to develop and provide more labs for advanced

  7. Delayed response to animate implied motion in human motion processing areas

    NARCIS (Netherlands)

    Lorteije, J.A.M.; Kenemans, J.L.; Jellema, T.; Lubbe, R.H.J. van der; Heer, F. de; Wezel, R.J.A. van

    2006-01-01

    Viewing static photographs of objects in motion evokes higher fMRI activation in the human medial temporal complex (MT+) than looking at similar photographs without this implied motion. As MT+ is traditionally thought to be involved in motion perception (and not in form perception), this finding sug

  8. Delayed Response to Animate Implied Motion in Human Motion Processing Areas

    NARCIS (Netherlands)

    Lorteije, Jeannette A.M.; Kenemans, J. Leon; Jellema, Tjeerd; Lubbe, van der Rob H.J.; Heer, de Frederiek; Wezel, van Richard J.A.

    2006-01-01

    Viewing static photographs of objects in motion evokes higher fMRI activation in the human medial temporal complex (MT+) than looking at similar photographs without this implied motion. As MT+ is traditionally thought to be involved in motion perception (and not in form perception), this finding sug

  9. A reevaluation of the vestibulo-ocular reflex: new ideas of its purpose, properties, neural substrate, and disorders

    Science.gov (United States)

    Leigh, R. J.; Brandt, T.

    1993-01-01

    Conventional views of the vestibulo-ocular reflex (VOR) have emphasized testing with caloric stimuli and by passively rotating patients at low frequencies in a chair. The properties of the VOR tested under these conditions differ from the performance of this reflex during the natural function for which it evolved--locomotion. Only the VOR (and not visually mediated eye movements) can cope with the high-frequency angular and linear perturbations of the head that occur during locomotion; this is achieved by generating eye movements at short latency (< 16 msec). Interpretation of vestibular testing is enhanced by the realization that, although the di- and trisynaptic components of the VOR are essential for this short-latency response, the overall accuracy and plasticity of the VOR depend upon a distributed, parallel network of neurons involving the vestibular nuclei. Neurons in this network variously upon a distributed, parallel network of neurons involving the vestibular nuclei. Neurons in this network variously encode inputs from the labyrinthine semicircular canals and otoliths, as well as from the visual and somatosensory systems. The central vestibular pathways branch to contact vestibular cortex (for perception) and the spinal cord (for control of posture). Thus, the vestibular nuclei basically coordinate the stabilization of gaze and posture, and contribute to the perception of verticality and self-motion. Consequently, brainstem disorders that disrupt the VOR cause not just only nystagmus, but also instability of posture (eg, increased fore-aft sway in patients with downbeat nystagmus) and disturbance of spatial orientation (eg, tilt of the subjective visual vertical in Wallenberg's syndrome).

  10. Outside home. Notes on reflexivity

    Directory of Open Access Journals (Sweden)

    Mara Clemente

    2017-01-01

    The paper proffers the idea in which a “reflexive process” on subjectivity can involve and/or hopefully involve the entire experience of the researcher, going beyond the borders of a single research. In the process, unexpected elements of subjectivity can come into play; in other cases the meaning attributed to them can change in time or can have a role different from what had been expected. Some elements, objects of epistemological analyses, as imposed by a reflexive approach, can become objects of attention also on the phenomenological level.

  11. Rapid motor learning in the translational vestibulo-ocular reflex

    Science.gov (United States)

    Zhou, Wu; Weldon, Patrick; Tang, Bingfeng; King, W. M.; Shelhamer, M. J. (Principal Investigator)

    2003-01-01

    Motor learning was induced in the translational vestibulo-ocular reflex (TVOR) when monkeys were repeatedly subjected to a brief (0.5 sec) head translation while they tried to maintain binocular fixation on a visual target for juice rewards. If the target was world-fixed, the initial eye speed of the TVOR gradually increased; if the target was head-fixed, the initial eye speed of the TVOR gradually decreased. The rate of learning acquisition was very rapid, with a time constant of approximately 100 trials, which was equivalent to or=1 d without any reinforcement, indicating induction of long-term synaptic plasticity. Although the learning generalized to targets with different viewing distances and to head translations with different accelerations, it was highly specific for the particular combination of head motion and evoked eye movement associated with the training. For example, it was specific to the modality of the stimulus (translation vs rotation) and the direction of the evoked eye movement in the training. Furthermore, when one eye was aligned with the heading direction so that it remained motionless during training, learning was not expressed in this eye, but only in the other nonaligned eye. These specificities show that the learning sites are neither in the sensory nor the motor limb of the reflex but in the sensory-motor transformation stage of the reflex. The dependence of the learning on both head motion and evoked eye movement suggests that Hebbian learning may be one of the underlying cellular mechanisms.

  12. The history of examination of reflexes.

    Science.gov (United States)

    Boes, Christopher J

    2014-12-01

    In the late 1800s, Wilhelm Erb, Joseph Babinski, William Gowers, and others helped develop the neurologic examination as we know it today. Erb was one of the first to emphasize a detailed and systematic neurologic exam and was co-discoverer of the muscle stretch reflex, Gowers began studying the knee jerk shortly after it was described, and Babinski focused on finding reliable signs that could differentiate organic from hysterical paralysis. These physicians and others emphasized the bedside examination of reflexes, which have been an important part of the neurologic examination ever since. This review will focus on the history of the examination of the following muscle stretch and superficial/cutaneous reflexes: knee jerk, jaw jerk, deep abdominal reflexes, superficial abdominal reflexes, plantar reflex/Babinski sign, and palmomental reflex. The history of reflex grading will also be discussed.

  13. Educating the Reflexive Practitioner

    Directory of Open Access Journals (Sweden)

    Marc J. Neveu

    2012-09-01

    wearing any clothes.Notwithstanding such issues, I do believe the studio holds the potentialto be an empowering learning experience. The intention of this article is to question the mode of instruction in an architectural studio. I’ve structured the paper in three parts. First, I will briefly describe the findingsof the study made by the Carnegie Foundation for the Advancementof Teaching known as the Boyer Report.2 To develop and support the findings of the Boyer Report, I introduce the work of the educator Donald Schön. Though I see much merit in the Boyer Report, and Schön’sproposals, I argue that a more nuanced approach is required. I will recommend, therefore, in the second section of this paper that a meansof architectural education as based on the Socratic method may be amore productive approach. My reading of the Socratic method is basedprimarily on early Socratic dialogues and I will specifically use Charmidesto illustrate the issues that I believe are relevant to studio pedagogy.3 From my analysis of Charmides I will, in the third section of the essay,describe how the Socratic method is beneficial to studio pedagogy threeways: reflexive, non-propositional, and finally how Socrates’ approachmay indeed be practical. This last section will be illustrated with a studentproject. It is my conjecture that the Socratic method offers insight intocurrent discussions of educational theory, namely student-centered,project-based learning.

  14. The reflexive case study method

    DEFF Research Database (Denmark)

    Rittenhofer, Iris

    2015-01-01

    This paper extends the international business research on small to medium-sized enterprises (SME) at the nexus of globalization. Based on a conceptual synthesis across disciplines and theoretical perspectives, it offers management research a reflexive method for case study research of postnational...

  15. Soleus stretch reflex during cycling

    DEFF Research Database (Denmark)

    Grey, Michael James; Pierce, C. W.; Milner, T. E.

    2001-01-01

    The modulation and strength of the human soleus short latency stretch reflex was investigated by mechanically perturbing the ankle during an unconstrained pedaling task. Eight subjects pedaled at 60 rpm against a preload of 10 Nm. A torque pulse was applied to the crank at various positions durin...

  16. Artificial balance: restoration of the vestibulo-ocular reflex in humans with a prototype vestibular neuroprosthesis.

    Science.gov (United States)

    Perez Fornos, Angelica; Guinand, Nils; van de Berg, Raymond; Stokroos, Robert; Micera, Silvestro; Kingma, Herman; Pelizzone, Marco; Guyot, Jean-Philippe

    2014-01-01

    The vestibular system plays a crucial role in the multisensory control of balance. When vestibular function is lost, essential tasks such as postural control, gaze stabilization, and spatial orientation are limited and the quality of life of patients is significantly impaired. Currently, there is no effective treatment for bilateral vestibular deficits. Research efforts both in animals and humans during the last decade set a solid background to the concept of using electrical stimulation to restore vestibular function. Still, the potential clinical benefit of a vestibular neuroprosthesis has to be demonstrated to pave the way for a translation into clinical trials. An important parameter for the assessment of vestibular function is the vestibulo-ocular reflex (VOR), the primary mechanism responsible for maintaining the perception of a stable visual environment while moving. Here we show that the VOR can be artificially restored in humans using motion-controlled, amplitude modulated electrical stimulation of the ampullary branches of the vestibular nerve. Three patients received a vestibular neuroprosthesis prototype, consisting of a modified cochlear implant providing vestibular electrodes. Significantly higher VOR responses were observed when the prototype was turned ON. Furthermore, VOR responses increased significantly as the intensity of the stimulation increased, reaching on average 79% of those measured in healthy volunteers in the same experimental conditions. These results constitute a fundamental milestone and allow us to envision for the first time clinically useful rehabilitation of patients with bilateral vestibular loss.

  17. Artificial balance: restoration of the vestibulo-ocular reflex in humans with a prototype vestibular neuroprosthesis

    Directory of Open Access Journals (Sweden)

    Angelica ePerez Fornos

    2014-04-01

    Full Text Available The vestibular system plays a crucial role in the multisensory control of balance. When vestibular function is lost, essential tasks such as postural control, gaze stabilization, and spatial orientation are limited and the quality of life of patients is significantly impaired. Currently there is no effective treatment for bilateral vestibular deficits. Research efforts both in animals and humans during the last decade set a solid background to the concept of using electrical stimulation to restore vestibular function. Still, the potential clinical benefit of a vestibular neuroprosthesis has to be demonstrated to pave the way for a translation into clinical trials. An important parameter for the assessment of vestibular function is the Vestibulo-Ocular Reflex (VOR, the primary mechanism responsible for maintaining the perception of a stable visual environment while moving. Here we show that the VOR can be artificially restored in humans using motion-controlled, amplitude modulated electrical stimulation of the ampullary branches of the vestibular nerve. Three patients received a vestibular neuroprosthesis prototype, consisting of a modified cochlear implant providing vestibular electrodes. Significantly higher VOR responses were observed when the prototype was turned ON. Furthermore, VOR responses increased significantly as the intensity of the stimulation increased, reaching on average 79% of those measured in healthy volunteers in the same experimental conditions. These results constitute a fundamental milestone and allow us to envision for the first time clinically useful rehabilitation of patients with bilateral vestibular loss.

  18. The relative weight of shape and non-rigid motion cues in object perception: a model of the parameters underlying dynamic object discrimination.

    Science.gov (United States)

    Vuong, Quoc C; Friedman, Alinda; Read, Jenny C A

    2012-03-16

    Shape and motion are two dominant cues for object recognition, but it can be difficult to investigate their relative quantitative contribution to the recognition process. In the present study, we combined shape and non-rigid motion morphing to investigate the relative contributions of both types of cues to the discrimination of dynamic objects. In Experiment 1, we validated a novel parameter-based motion morphing technique using a single-part three-dimensional object. We then combined shape morphing with the novel motion morphing technique to pairs of multipart objects to create a joint shape and motion similarity space. In Experiment 2, participants were shown pairs of morphed objects from this space and responded "same" on the basis of motion-only, shape-only, or both cues. Both cue types influenced judgments: When responding to only one cue, the other cue could be ignored, although shape cues were more difficult to ignore. When responding on the basis of both cues, there was an overall bias to weight shape cues more than motion cues. Overall, our results suggest that shape influences discrimination more than motion even when both cue types have been made quantitatively equivalent in terms of their individual discriminability.

  19. Distance and Size Perception in Astronauts during Long-Duration Spaceflight

    Directory of Open Access Journals (Sweden)

    Gilles Clément

    2013-12-01

    Full Text Available Exposure to microgravity during spaceflight is known to elicit orientation illusions, errors in sensory localization, postural imbalance, changes in vestibulo-spinal and vestibulo-ocular reflexes, and space motion sickness. The objective of this experiment was to investigate whether an alteration in cognitive visual-spatial processing, such as the perception of distance and size of objects, is also taking place during prolonged exposure to microgravity. Our results show that astronauts on board the International Space Station exhibit biases in the perception of their environment. Objects’ heights and depths were perceived as taller and shallower, respectively, and distances were generally underestimated in orbit compared to Earth. These changes may occur because the perspective cues for depth are less salient in microgravity or the eye-height scaling of size is different when an observer is not standing on the ground. This finding has operational implications for human space exploration missions.

  20. 3D Perception of Biomimetic Eye Based on Motion Vision and Stereo Vision%仿生眼运动视觉与立体视觉3维感知

    Institute of Scientific and Technical Information of China (English)

    王庆滨; 邹伟; 徐德; 张峰

    2015-01-01

    In order to overcome the narrow visual field of binocular vision and the low precision of monocular vision, a binocular biomimetic eye platform with 4 rotational degrees of freedom is designed based on the structural characteristics of human eyes, so that the robot can achieve human-like environment perception with binocular stereo vision and monoc-ular motion vision. Initial location and parameters calibration of the biomimetic eye platform are accomplished based on the vision alignment strategy and hand-eye calibration. The methods of binocular stereo perception and monocular motion stereo perception are given based on the dynamically changing external parameters. The former perceives the 3D information through the two images obtained by two cameras in real-time and their relative posture, and the latter perceives the 3D infor-mation by synthesize multiple images obtained by one camera and its corresponding postures at multiple adjacent moments. Experimental results shows that the relative perception accuracy of binocular vision is 0.38% and the relative perception accuracy of monocular motion vision is 0.82%. In conclusion, the method proposed can broaden the field of binocular vision, and ensure the accuracy of binocular perception and monocular motion perception.%为使机器人同时具备双目立体视觉和单目运动视觉的仿人化环境感知能力,克服双目视场狭窄、单目深度感知精度低的缺陷,本文基于人眼结构特点,设计了一个具有4个旋转自由度的双目仿生眼平台,并分别基于视觉对准策略和手眼标定技术实现了该平台的初始定位和参数标定.给出了基于外部参数动态变化的双目立体感知方法和单目运动立体感知方法,前者通过两架摄像机实时获取的图像信息以及摄像机相对位姿信息进行3维感知,后者综合利用单个摄像机在多个相邻时刻获取的多个图像及其对应姿态进行3维感知.实验结果中的双目

  1. Reflexivity in Narratives on Practice

    DEFF Research Database (Denmark)

    Jakobsen, Helle Nordentoft; Olesen, Lektor Birgitte Ravn

    Previous research has shown how reflexivity is a precondition for knowledge co-production through productive dialogue in organisational contexts because it entails a re-ordering, re-arranging and re-designing of what one knows and therefore creates new angles of vision. In this paper, we draw...... on Bakhtinian dialogic communication theory and discursive psychology to investigate the written practice narratives of 23 students on a Masters Degree Programme in Educational Studies, focusing on how the process of writing narratives accentuates reflexivity. Our findings indicate that the narratives invite...... a dialogic conception of practice as they entail a conceptual reframing of key elements in practice. In addition, the narratives expose a situational and relational, rather than normative, focus which allows for reflections on emotional and bodily experiences. In conclusion, we argue that practice narratives...

  2. Integrating Reflexivity in Livelihoods Research

    DEFF Research Database (Denmark)

    Prowse, Martin

    2010-01-01

    Much poverty and development research is not explicit about its methodology or philosophical foundations. Based on the extended case method of Burawoy and the epistemological standpoint of critical realism, this paper discusses a methodological approach for reflexive inductive livelihoods researc...... that overcomes the unproductive social science dualism of positivism and social constructivism. The approach is linked to a conceptual framework and a menu of research methods that can be sequenced and iterated in light of research questions.......Much poverty and development research is not explicit about its methodology or philosophical foundations. Based on the extended case method of Burawoy and the epistemological standpoint of critical realism, this paper discusses a methodological approach for reflexive inductive livelihoods research...

  3. Reflexive fatherhood in everyday life

    DEFF Research Database (Denmark)

    Westerling, Allan

    2015-01-01

    This article looks at fathering practices in Denmark, using the findings from a research project on everyday family life in Denmark. It takes a social psychological perspective and employs discursive psychology and theories about reflexive modernisation. It shows how fathers orient towards intimacy...... this analysis and discussion, the article offers a way to understand the complexities of fathering in everyday life from the perspective of fathers....

  4. Integrating Reflexivity in Livelihoods Research

    DEFF Research Database (Denmark)

    Prowse, Martin

    2010-01-01

    Much poverty and development research is not explicit about its methodology or philosophical foundations. Based on the extended case method of Burawoy and the epistemological standpoint of critical realism, this paper discusses a methodological approach for reflexive inductive livelihoods researc...... that overcomes the unproductive social science dualism of positivism and social constructivism. The approach is linked to a conceptual framework and a menu of research methods that can be sequenced and iterated in light of research questions....

  5. Classifying Motion.

    Science.gov (United States)

    Duzen, Carl; And Others

    1992-01-01

    Presents a series of activities that utilizes a leveling device to classify constant and accelerated motion. Applies this classification system to uniform circular motion and motion produced by gravitational force. (MDH)

  6. Advancement of motion psychophysics: review 2001-2010.

    Science.gov (United States)

    Nishida, Shin'ya

    2011-12-05

    This is a survey of psychophysical studies of motion perception carried out mainly in the last 10 years. It covers a wide range of topics, including the detection and interactions of local motion signals, motion integration across various dimensions for vector computation and global motion perception, second-order motion and feature tracking, motion aftereffects, motion-induced mislocalizations, timing of motion processing, cross-attribute interactions for object motion, motion-induced blindness, and biological motion. While traditional motion research has benefited from the notion of the independent "motion processing module," recent research efforts have been also directed to aspects of motion processing in which interactions with other visual attributes play critical roles. This review tries to highlight the richness and diversity of this large research field and to clarify what has been done and what questions have been left unanswered.

  7. A TMS study on the contribution of visual area V5 to the perception of implied motion in art and its appreciation.

    Science.gov (United States)

    Cattaneo, Zaira; Schiavi, Susanna; Silvanto, Juha; Nadal, Marcos

    2017-01-01

    Over the last decade, researchers have sought to understand the brain mechanisms involved in the appreciation of art. Previous studies reported an increased activity in sensory processing regions for artworks that participants find more appealing. Here we investigated the intriguing possibility that activity in cortical area V5-a region in the occipital cortex mediating physical and implied motion detection-is related not only to the generation of a sense of motion from visual cues used in artworks, but also to the appreciation of those artworks. Art-naïve participants viewed a series of paintings and quickly judged whether or not the paintings conveyed a sense of motion, and whether or not they liked them. Triple-pulse TMS applied over V5 while viewing the paintings significantly decreased the perceived sense of motion, and also significantly reduced liking of abstract (but not representational) paintings. Our data demonstrate that V5 is involved in extracting motion information even when the objects whose motion is implied are pictorial representations (as opposed to photographs or film frames), and even in the absence of any figurative content. Moreover, our study suggests that, in the case of untrained people, V5 activity plays a causal role in the appreciation of abstract but not of representational art.

  8. Startle modulation during emotional anticipation and perception.

    Science.gov (United States)

    Sege, Christopher T; Bradley, Margaret M; Lang, Peter J

    2014-10-01

    The startle reflex is potentiated when anticipating emotional, compared to neutral, pictures. This study investigated the time course of reflex modulation during anticipation and the impact of informative cuing on picture perception. Colors were used to signal the thematic content of emotional and neutral scenes; blink response modulation was measured by presenting acoustic startle probes 3, 2, or 1 s before picture onset or 2 s after picture onset. During anticipation of neutral scenes, blink magnitude showed increasing attenuation as picture onset approached, consistent with a modality-directed vigilance account. Conversely, when anticipating emotional scenes, reflex magnitude did not change over time, and blinks elicited closest to picture onset were potentiated compared to neutral. During perception, the expected reflex potentiation for unpleasant pictures was not found, suggesting that cuing may dampen defensive activation. Copyright © 2014 Society for Psychophysiological Research.

  9. [Clinical relevance of cardiopulmonary reflexes in anesthesiology].

    Science.gov (United States)

    Guerri-Guttenberg, R A; Siaba-Serrate, F; Cacheiro, F J

    2013-10-01

    The baroreflex, chemoreflex, pulmonary reflexes, Bezold-Jarisch and Bainbridge reflexes and their interaction with local mechanisms, are a demonstration of the richness of cardiovascular responses that occur in human beings. As well as these, the anesthesiologist must contend with other variables that interact by attenuating or accentuating cardiopulmonary reflexes such as, anesthetic drugs, surgical manipulation, and patient positioning. In the present article we review these reflexes and their clinical relevance in anesthesiology. Copyright © 2012 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Published by Elsevier España. All rights reserved.

  10. Neural reflexes in inflammation and immunity

    National Research Council Canada - National Science Library

    Andersson, Ulf; Tracey, Kevin J

    2012-01-01

    .... Development of advanced neurophysiological and immunological techniques recently enabled the study of reflex neural circuits that maintain immunological homeostasis, and are essential for health in mammals...

  11. Reflexive Aero Structures for Enhanced Survivability Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Cornerstone Research Group Inc. (CRG) will develop an advanced reflexive structure technology system to increase the survivability of future systems constructed of...

  12. Visual suppression of the vestibulo-ocular reflex during space flight

    Science.gov (United States)

    Uri, John J.; Thornton, William E.; Moore, Thomas P.; Pool, Sam L.

    1989-01-01

    Visual suppression of the vestibulo-ocular reflex was studied in 16 subjects on 4 Space Shuttle missions. Eye movements were recorded by electro-oculography while subjects fixated a head mounted target during active sinusoidal head oscillation at 0.3 Hz. Adequacy of suppression was evaluated by the number of nystagmus beats, the mean amplitude of each beat, and the cumulative amplitude of nystagmus during two head oscillation cycles. Vestibulo-ocular reflex suppression was unaffected by space flight. Subjects with space motion sickness during flight had significantly more nystagmus beats than unaffected individuals. These susceptible subjects also tended to have more nystagmus beats before flight.

  13. Alpha motion based on a motion detector, but not on the Müller-Lyer illusion

    Science.gov (United States)

    Suzuki, Masahiro

    2014-07-01

    This study examined the mechanism of alpha motion, the apparent motion of the Müller-Lyer figure's shaft that occurs when the arrowheads and arrow tails are alternately presented. The following facts were found: (a) reduced exposure duration decreased the amount of alpha motion, and this phenomenon was not explainable by the amount of the Müller-Lyer illusion; (b) the motion aftereffect occurred after adaptation to alpha motion; (c) occurrence of alpha motion became difficult when the temporal frequency increased, and this characteristic of alpha motion was similar to the characteristic of a motion detector that motion detection became difficult when the temporal frequency increased from the optimal frequency. These findings indicated that alpha motion occurs on the basis of a motion detector but not on the Müller-Lyer illusion, and that the mechanism of alpha motion is the same as that of general motion perception.

  14. Reflexivity in Narratives on Practice

    DEFF Research Database (Denmark)

    Jakobsen, Helle Nordentoft; Olesen, Lektor Birgitte Ravn

    on Bakhtinian dialogic communication theory and discursive psychology to investigate the written practice narratives of 23 students on a Masters Degree Programme in Educational Studies, focusing on how the process of writing narratives accentuates reflexivity. Our findings indicate that the narratives invite...... a dialogic conception of practice as they entail a conceptual reframing of key elements in practice. In addition, the narratives expose a situational and relational, rather than normative, focus which allows for reflections on emotional and bodily experiences. In conclusion, we argue that practice narratives...

  15. Two ways to support reflexivity

    DEFF Research Database (Denmark)

    Adriansen, Hanne Kirstine; Knudsen, Hanne

    2013-01-01

    Management (MEM). MEM provides the participating managers with a new language that can give them a critical distance to the overload of expectations they meet at work and MEM teaches the participants to translate this new language into practice. The pedagogy used for this is labelled ‘experimental management......’. This requires participants to conduct experiments in their own organization, to reflect on and analyse their experiences with concepts from the curriculum. While the new language and the experimental teaching format are difficult, the participants learn a reflexive practice that can enable them to life up...

  16. Structural cure for reflex syncope?

    Science.gov (United States)

    Sulke, Neil; Eysenck, William; Badiani, Sveeta; Furniss, Stephen

    2016-01-20

    The ROX Coupler is a device that allows creation of a central arteriovenous anastomosis at the iliac level. The device has been shown to improve exercise capacity in patients with chronic obstructive pulmonary disease and is CE marked for the treatment of resistant and uncontrolled hypertension. Reflex syncope is a challenging clinical condition with limited proven therapeutic options. We describe the resolution of symptoms and tilt table response of a patient who underwent insertion of a ROX Coupler to treat hypertension, and also incidentally had pre-existing vasodepressor syncope.

  17. Perception coherence zones in flight simulation

    NARCIS (Netherlands)

    Valente Pais, A.R.; Paassen, M.M. van; Mulder, M.; Wentink, M.

    2009-01-01

    The importance of motion perception knowledge for flight simulation is widely recognized. The development and tuning of motion filters relies on understanding the human motion perception mechanisms and its limitations. Particularly interesting for flight simulation is the study of visual-vestibular

  18. The Central Nervous Connections Involved in the Vomiting Reflex

    Science.gov (United States)

    Brizzee, K. R.; Mehler, W. R.

    1986-01-01

    The vomiting reflex may be elicited by a number of different types or classes of stimuli involving many varieties of receptor structures and considerable diversity in afferent pathways and central connections. Central relay or mediating structures thus may vary widely according to the type of initial emetic stimulus. The emetic circuits which have been most completely delineated to date are probably those in which the Chemoreceptor Trigger Zone (CTZ) in the Area Postrema (AP) functions as a key mediating structure. Even in this system, however, there are large gaps in our knowledge of the nerve tracts and central nervous connections involved. Knowledge of most other emetic circuits subserving the emetic reflex resulting from many diverse types of stimuli such, for example, as emotional stress (e.g. psychogenic vomiting, Wruble et al. 1982), pain (e.g. testicular trauma), and chemical or mechanical irritation of the gastrointestinal tract or urinary tract is quite incomplete at this time, thus precluding any very adequate description of their central connections at present. One physiological system, however, which has received considerable attention recently in relation to the vomiting reflex elicited by motion stimuli is the vestibular system. Due to the paucity of data on central nervous connections of several or the non-vestibular types of emetic stimuli cited above, we will devote most of our attention in this brief review to the central connections of the vestibular system which seem likely to be involved in the vomiting response to motion stimuli. However, the latter part of the review will be concerned with the concept of the reticular vomiting centre in relation to the ParviCellular Reticular Formation (PCRF), and will thus probably pertain to all of the many classes of emetic stimuli since it will address the question of the final common emetic pathway.

  19. The Dynamics of the Stapedial Acoustic Reflex.

    Science.gov (United States)

    Moss, Sherrin Mary

    Available from UMI in association with The British Library. This thesis aims to separate the neural and muscular components of the stapedial acoustic reflex, both anatomically and physiologically. It aims to present an hypothesis to account for the differences between ipsilateral and contralateral reflex characteristics which have so far been unexplained, and achieve a greater understanding of the mechanisms underlying the reflex dynamics. A technique enabling faithful reproduction of the time course of the reflex is used throughout the experimental work. The technique measures tympanic membrane displacement as a result of reflex stapedius muscle contraction. The recorded response can be directly related to the mechanics of the middle ear and stapedius muscle contraction. Some development of the technique is undertaken by the author. A model of the reflex neural arc and stapedius muscle dynamics is evolved that is based upon a second order system. The model is unique in that it includes a latency in the ipsilateral negative feedback loop. Oscillations commonly observed on reflex responses are seen to be produced because of the inclusion of a latency in the feedback loop. The model demonstrates and explains the complex relationships between neural and muscle dynamic parameters observed in the experimental work. This more comprehensive understanding of the interaction between the stapedius dynamics and the neural arc of the reflex would not usually have been possible using human subjects, coupled with a non-invasive measurement technique. Evidence from the experimental work revealed the ipsilateral reflex to have, on average, a 5 dB lower threshold than the contralateral reflex. The oscillatory charcteristics, and the steady state response, of the contralateral reflex are also seen to be significantly different from those of the ipsilateral reflex. An hypothesis to account for the experimental observations is proposed. It is propounded that chemical neurotransmitters

  20. 运动知觉预测训练在警务实战教学中的应用研究%Application of motion perceptional prediction training in policing practice teaching

    Institute of Scientific and Technical Information of China (English)

    周波

    2015-01-01

    The study used motion perception learning theory to explore the feasibility of specialized perception training in improving the perceptional prediction ability of students in police colleges.The participants were divided into two groups:the control group and the experimental group and pretest the level of the two groups was basically the same.The control group adopted traditional teaching method while the experimental group added specialized perception learning but kept the same class hours.Before the test,there was no significant difference in search,recognition and perceptual prediction between the two groups;after the test,however,the experimental group obviously improved the ability in search,recognition and perceptual prediction and there was statistically difference between the two groups.The experiment has showed that motion perceptual prediction training can well guide the policing practice and it is suggested that police colleges add this training in the police actual combat teaching and practicing.%本研究以运动知觉学习理论为支撑,探索专门化知觉训练对提高警察院校学员知觉预测能力的可行性。实验设实验组和对照组,对照组采用传统教学方法,实验组在课时不变情况下增加专门化知觉学习;实验前,两组学员之间在搜索、识别和知觉预判上不具有显著性差异;实验后,与对照组相比,实验组学员在警务实战知觉预测能力中的搜索、识别和知觉预判上都有显著提高,经统计学分析两者之间具有显著性差异。实验证明,运动认知知觉预测训练对警务实战技能具有积极作用,建议警察院校警务技能教学、训练中应增加运动知觉预测能力训练。

  1. [Non-reflex activity of the CNS].

    Science.gov (United States)

    Brozek, G

    1995-06-01

    Recent studies of biological rhythms have modified Sherrington's concept of nervous system as exclusively reflexive to include the fact that some neural activity is also endogenously rhythmic. Reflexes are undoubtedly the most important components of animal's and human behavior. But are reflexes the basic units of all complex movements and acts? Rhythmical movements such as respiration, walking and running and other forms of locomotion, as well as rhythmical alimentary processes such as respiration, walking and running and other forms of locomotion, as well as rhythmical alimentary processes such as licking, mastication, and the peristaltic propulsion of nutrients and waste are examples of acts controlled by intrinsic oscillators, so called central pattern generators. Information from the periphery is, however, essential for controlling the extent and rate of movements. Between reflex and non-reflex activity it is possible to place complex species-specific responses called by ethologists fixed-action patterns. Recent investigators have shown that many complex sequences of behavior like speech or piano playing are determined by an internal plan, rather than being generated by a "chain" of reflexes. Non-reflexive activity appears earlier in ontogeny, and is probably phylogenetically older than reflexes.

  2. Reflexive choice in Dutch and German

    NARCIS (Netherlands)

    Hendriks, Petra; Hoeks, John C. J.; Spenader, Jennifer

    2014-01-01

    Standard Dutch and German have two reflexive forms: a weak form ('zich' in Dutch and 'sich' in German) and a strong form ('zichzelf' in Dutch and 'sich selbst' in German). The choice between the two reflexive forms in Dutch has been explained by the selectional restrictions of the verb, distinguishi

  3. Reflexivity in Teams: A Measure and Correlates

    NARCIS (Netherlands)

    M.C. Schippers (Michaéla); D.N. den Hartog (Deanne); P.L. Koopman (Paul)

    2005-01-01

    textabstractReflexivity -the extent to which teams reflect upon and modify their functioning- has been identified as a possible key factor in the effectiveness of work teams. The aim of the present study was to develop a questionnaire to measure (aspects of) reflexivity, with a focus on team reflect

  4. Axon reflexes in human cold exposed fingers

    NARCIS (Netherlands)

    Daanen, H.A.M.; Ducharme, M.B.

    2000-01-01

    Exposure of fingers to severe cold induces cold induced vasodilation (CIVD). The mechanism of CIVD is still debated. The original theory states that an axon reflex causes CIVD. To test this hypothesis, axon reflexes were evoked by electrical stimulation of the middle fingers of hands immersed in

  5. Axon reflexes in human cold exposed fingers

    NARCIS (Netherlands)

    Daanen, H.A.M.; Ducharme, M.B.

    2000-01-01

    Exposure of fingers to severe cold induces cold induced vasodilation (CIVD). The mechanism of CIVD is still debated. The original theory states that an axon reflex causes CIVD. To test this hypothesis, axon reflexes were evoked by electrical stimulation of the middle fingers of hands immersed in wat

  6. [Cutaneo-muscular reflexes of the human hand. II. Neurophysiologic aspects of reflex organization and coordination].

    Science.gov (United States)

    Meinck, H M; Berkefeld, J; Conrad, B

    1987-09-01

    The organization and coordination of cutaneo-muscular reflexes of human finger and arm muscles to electrical stimulation of the digital nerves were investigated in 14 healthy volunteers. Thumb and finger muscles, although antagonists, showed homonymous reflex effects whereas the wrist and elbow muscles exhibited an reciprocally alternating reflex pattern in pairs of antagonists (Fig. 1). The mechanographical correlate of the homonymous reflex activity in distal muscles was a short release (Fig. 6). The receptive field for evoking such reflex effects covered both the palmar and dorsal surfaces of the fingers (Fig. 2). However, with stimulation of the thumb, the muscles of the fingers and of the wrist showed reflex reversal (Figs 3, 5). If the stimulus was moved from the second to the fifth fingers, a successive attenuation of the transcortical reflex component was seen (Fig. 4). It is concluded that the reflexes investigated are complex flexor reflexes comprising both a distal release and a proximal flexion synergy. According to opposition of the thumb in grasping, the receptive field terminates between thumb and index finger. These reflexes are supposed to have no assisting function during corticalized manipulatory movements--in contrast to the long-loop reflexes evoked by epicritic sensibility. The transcortical servo is blocked if the eliciting stimulus is contaminated by nociceptive signals; its receptive field is confined to those fingers used in the precision grip.

  7. Reliability of the NINDS Myotatic Reflex Scale.

    Science.gov (United States)

    Litvan, I; Mangone, C A; Werden, W; Bueri, J A; Estol, C J; Garcea, D O; Rey, R C; Sica, R E; Hallett, M; Bartko, J J

    1996-10-01

    The assessment of deep tendon reflexes is useful for localization and diagnosis of neurologic disorders, but only a few studies have evaluated their reliability. We assessed the reliability of four neurologists, instructed in two different countries, in using the National Institute of Neurological Disorders and Stroke (NINDS) Myotatic Reflex Scale. To evaluate the role of training in using the scale, the neurologists randomly and blindly evaluated a total of 80 patients, 40 before and 40 after a training session. Inter- and intraobserver reliability were measured with kappa statistics. Our results showed substantial to near-perfect intraobserver reliability, and moderate-to-substantial interobserver reliability of the NINDS Myotatic Reflex Scale. The reproducibility was better for reflexes in the lower than in the upper extremities. Neither educational background nor the training session influenced the reliability of our results. The NINDS Myotatic Reflex Scale has sufficient reliability to be adopted as a universal scale.

  8. [Urinary urgency and reflex incontinence].

    Science.gov (United States)

    Madersbacher, H

    1991-07-01

    Urge and reflex incontinence are caused by detrusor dysfunction:urgency may be due to hyperactivity or hypersensitivity of the bladder. Neurogenic hyperactivity of the detrusor is called detrusor hyperreflexia: the neurogenic uninhibited bladder is caused by incomplete, and the so-called reflex bladder by complete, suprasacral lesions. The pathophysiology of symptomatic and idiopathic detrusor hyperactivity and the therapeutic armentarium are described. Bladder drill together with biofeedback and pharmacotherapy with spasmolytic drugs - several potent spasmolytic drugs with different modes of action are available - are the basis of treatment for hyperactivity and hypersensitivity of the detrusor. An alternative is electrostimulation: stimulation of the afferents of the pudendal nerve, via the pelvic floor (anal, vaginal), percutaneously (dorsal nerve of the penis, clitoric nerve) or by the implantation of electrodes results in inhibition of the detrusor. Most (80-90%) patients can be treated successfully by conservative means. Operative measurements comprise bladder denervation and bladder augmentation. The results of bladder denervation by transtrigonal phenolization of the pelvic plexus are highly controversial. In patients with uncontrollable hyperactivity of the detrusor, augmentation of the bladder (e.g. clam ileocystoplasty) is the method of choice, while for those with uncontrollable hypersensitivity of the detrusor, cystectomy followed by bladder substitution should be performed as a last resort. Treatment for urinary incontinence due to detrusor hyperreflexia must be selected bearing in mind that bladder emptying is inadequate, in most cases because of dyssynergia between detrusor and external sphincter. Therapy is basically aimed at transforming hyperreflexia of the detrusor into hyporeflexia, primarily by potent spasmolytic drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

  9. Cutaneous reflex modulation and self-induced reflex attenuation in cerebellar patients.

    Science.gov (United States)

    Hoogkamer, Wouter; Van Calenbergh, Frank; Swinnen, Stephan P; Duysens, Jacques

    2015-02-01

    Modulation of cutaneous reflexes is important in the neural control of walking, yet knowledge about underlying neural pathways is still incomplete. Recent studies have suggested that the cerebellum is involved. Here we evaluated the possible roles of the cerebellum in cutaneous reflex modulation and in attenuation of self-induced reflexes. First we checked whether leg muscle activity during walking was similar in patients with focal cerebellar lesions and in healthy control subjects. We then recorded cutaneous reflex activity in leg muscles during walking. Additionally, we compared reflexes after standard (computer triggered) stimuli with reflexes after self-induced stimuli for both groups. Biceps femoris and gastrocnemius medialis muscle activity was increased in the patient group compared with the control subjects, suggesting a coactivation strategy to reduce instability of gait. Cutaneous reflex modulation was similar between healthy control subjects and cerebellar patients, but the latter appeared less able to attenuate reflexes to self-induced stimuli. This suggests that the cerebellum is not primarily involved in cutaneous reflex modulation but that it could act in attenuation of self-induced reflex responses. The latter role in locomotion would be consistent with the common view that the cerebellum predicts sensory consequences of movement. Copyright © 2015 the American Physiological Society.

  10. Studies of the vestibulo-ocular reflex on STS 4, 5 and 6

    Science.gov (United States)

    Thornton, William E.; Pool, Sam L.; Moore, Thomas P.; Uri, John J.

    1988-01-01

    The vestibulo-ocular reflex (VOR) may be altered by weightlessness. Since this reflex plays a large role in visual stabilization, it was important to document any changes caused by space flight. This is a report on findings on STS-4 through 6 and is part of a larger study of neurosensory adaptation done on STS-4 through 8. Voluntary horizontal head oscillations at 1/3 Hz with amplitude of 30 deg right and left of center were recorded by a potentiometer and compared to eye position recorded by electroculography under the following conditions: eyes open, head fixed, tracking horizontal targets switched 0, 15, and 30 degrees right and left (optokinetic reflex - OKR - and calibration); eyes open and fixed on static external target with oscillation, (vestibulo ocular reflex, eyes closed - VOR EC); eyes open and wearing opaque goggles with target fixed in imagination (vestibulo-ocular reflex, eyes shaded - VOR ES); and eyes open and fixed on a head synchronized target with head oscillation (VOR suppression). No significant changes were found in voluntary head oscillation frequency or amplitude in those with (n=5), and without (n=3), space motion sickness (SMS), with phase of flight or test condition. Variations in head oscillation were too small to have produced detectable changes in test results.

  11. Brainstem reflexes in patients with familial dysautonomia.

    Science.gov (United States)

    Gutiérrez, Joel V; Norcliffe-Kaufmann, Lucy; Kaufmann, Horacio

    2015-03-01

    Several distinctive clinical features of patients with familial dysautonomia (FD) including dysarthria and dysphagia suggest a developmental defect in brainstem reflexes. Our aim was to characterize the neurophysiological profile of brainstem reflexes in these patients. We studied the function of sensory and motor trigeminal tracts in 28 patients with FD. All were homozygous for the common mutation in the IKAP gene. Each underwent a battery of electrophysiological tests including; blink reflexes, jaw jerk reflex, masseter silent periods and direct stimulation of the facial nerve. Responses were compared with 25 age-matched healthy controls. All patients had significantly prolonged latencies and decreased amplitudes of all examined brainstem reflexes. Similar abnormalities were seen in the early and late components. In contrast, direct stimulation of the facial nerve revealed relative preservation of motor responses. The brainstem reflex abnormalities in FD are best explained by impairment of the afferent and central pathways. A reduction in the number and/or excitability of trigeminal sensory axons is likely the main problem. These findings add further evidence to the concept that congenital mutations of the elongator-1 protein (or IKAP) affect the development of afferent neurons including those carrying information for the brainstem reflex pathways. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  12. Reflexivity and technology in adult learning

    Directory of Open Access Journals (Sweden)

    Neil Selwyn

    2005-03-01

    Full Text Available It is argued by influential commentators such as Ulrich Beck and Scott Lash that we now live in a ‘reflexively modern' age. People are seen to now be free of the structures of modern society and driven instead by individualised opportunities to reflexively engage with their fast-changing social worlds and identities. Taking the notion of reflexive modernisation as its starting point, this paper explores the roles that information technologies (ITs may play in supporting adults' reflexive judgements about, and reflexive engagements with, education and learning. Through an analysis of interview data with 100 adults in the UK the paper finds that whilst a minority of interviewees were using ITs to support and inform reflexive engagementwith learning, the majority of individuals relayed little sign of technology-supported reflexivity when it came to their (nonengagement with education. For most people ITs were found, at best, to reinforce pre-established tendencies to ‘drift' through the formal education system. The paper concludes by considering the implications of these findings for ongoing efforts in developed countries to establish technology-supported ‘learning societies'.

  13. Motion scaling for high-performance driving simulators

    NARCIS (Netherlands)

    Berthoz, A.; Bles, W.; Bülthoff, H.H.; Correia Grácio, B.J.; Feenstra, P.; Filliard, N.; Hühne, R.; Kemeny, A.; Mayrhofer, M.; Mulder, M.; Nusseck, H.G.; Pretto, P.; Reymond, G.; Schlüsselberger, R.; Schwandtner, J.; Teufel, H.; Vailleau, B.; Paassen, M.M.R. van; Vidal, M.; Wentink, M.

    2013-01-01

    Advanced driving simulators aim at rendering the motion of a vehicle with maximum fidelity, which requires increased mechanical travel, size, and cost of the system. Motion cueing algorithms reduce the motion envelope by taking advantage of limitations in human motion perception, and the most common

  14. The Multiple Faces of Reflexive Research Designs

    Directory of Open Access Journals (Sweden)

    Karl H. Müller

    2015-10-01

    Full Text Available Reflexive research can be grouped into five clusters with circular relations between two elements x ↔ x, namely circular relations between observers, between scientific building blocks like concepts, theories or models, between systemic levels, between rules and rule systems or as circular relations or x ↔ y between these four components. By far the most important cluster is the second cluster which becomes reflexive through a re-entry operation RE into a scientific element x and which establishes its circular formation as x(x. Many of the research problems in these five clusters in reflexivity research are still unexplored and pose grand challenges for future research.

  15. Ranges of bimodule projections and reflexivity

    CERN Document Server

    Eleftherakis, G K

    2011-01-01

    We develop a general framework for reflexivity in dual Banach spaces, motivated by the question of when the weak* closed linear span of two reflexive masa-bimodules is automatically reflexive. We establish an affirmative answer to this question in a number of cases by examining two new classes of masa-bimodules, defined in terms of ranges of masa-bimodule projections. We give a number of corollaries of our results concerning operator and spectral synthesis, and show that the classes of masa-bimodules we study are operator synthetic if and only if they are strong operator Ditkin.

  16. △'-Reflexive Modules and Cogen(P)-Linear Compactness

    Institute of Scientific and Technical Information of China (English)

    Lin Xin

    2005-01-01

    In this paper, we introduce the notion of △'-reflexive modules. We investigate the reflexive modules with respect to a partial cotilting (bi)module and obtain a connection between △'-reflexive modules and Cogen(P)-linearly compact modules. The main results generalize the results on reflexive modules with respect to a cotilting bimodule.

  17. Fractional motions

    Energy Technology Data Exchange (ETDEWEB)

    Eliazar, Iddo I., E-mail: eliazar@post.tau.ac.il [Holon Institute of Technology, P.O. Box 305, Holon 58102 (Israel); Shlesinger, Michael F., E-mail: mike.shlesinger@navy.mil [Office of Naval Research, Code 30, 875 N. Randolph St., Arlington, VA 22203 (United States)

    2013-06-10

    Brownian motion is the archetypal model for random transport processes in science and engineering. Brownian motion displays neither wild fluctuations (the “Noah effect”), nor long-range correlations (the “Joseph effect”). The quintessential model for processes displaying the Noah effect is Lévy motion, the quintessential model for processes displaying the Joseph effect is fractional Brownian motion, and the prototypical model for processes displaying both the Noah and Joseph effects is fractional Lévy motion. In this paper we review these four random-motion models–henceforth termed “fractional motions” –via a unified physical setting that is based on Langevin’s equation, the Einstein–Smoluchowski paradigm, and stochastic scaling limits. The unified setting explains the universal macroscopic emergence of fractional motions, and predicts–according to microscopic-level details–which of the four fractional motions will emerge on the macroscopic level. The statistical properties of fractional motions are classified and parametrized by two exponents—a “Noah exponent” governing their fluctuations, and a “Joseph exponent” governing their dispersions and correlations. This self-contained review provides a concise and cohesive introduction to fractional motions.

  18. Emotional scene content drives the saccade generation system reflexively.

    Science.gov (United States)

    Nummenmaa, Lauri; Hyönä, Jukka; Calvo, Manuel G

    2009-04-01

    The authors assessed whether parafoveal perception of emotional content influences saccade programming. In Experiment 1, paired emotional and neutral scenes were presented to parafoveal vision. Participants performed voluntary saccades toward either of the scenes according to an imperative signal (color cue). Saccadic reaction times were faster when the cue pointed toward the emotional picture rather than toward the neutral picture. Experiment 2 replicated these findings with a reflexive saccade task, in which abrupt luminosity changes were used as exogenous saccade cues. In Experiment 3, participants performed vertical reflexive saccades that were orthogonal to the emotional-neutral picture locations. Saccade endpoints and trajectories deviated away from the visual field in which the emotional scenes were presented. Experiment 4 showed that computationally modeled visual saliency does not vary as a function of scene content and that inversion abolishes the rapid orienting toward the emotional scenes. Visual confounds cannot thus explain the results. The authors conclude that early saccade target selection and execution processes are automatically influenced by emotional picture content. This reveals processing of meaningful scene content prior to overt attention to the stimulus.

  19. Research on the Application of Motion Perception in Caricature and Animation Creation%论运动知觉在动漫创作中的应用

    Institute of Scientific and Technical Information of China (English)

    庄唯

    2012-01-01

    在动漫创作中,创作者如果忽视对“运动知觉”的一些基本原理的应用,必然会影响动画片制作的效率和质量。文章结合电影心理学的相关理论,通过实例比较和分析,探讨“运动知觉”这一原理在漫画、二维动画片及三维动画片创作中的应用及其意义。%The neglect of some basic principles of "motion perception" will influence the efficiency and quality of the creators" caricature and animation creation. Based on the related theories of film psychol- ogy, and by means of case comparison and analysis, this paper discusses the application of the "motion perception" in the creation of caricature, two-dimensional and three-dimensional animations and its significance.

  20. Unconscious local motion alters global image speed.

    Directory of Open Access Journals (Sweden)

    Sieu K Khuu

    Full Text Available Accurate motion perception of self and object speed is crucial for successful interaction in the world. The context in which we make such speed judgments has a profound effect on their accuracy. Misperceptions of motion speed caused by the context can have drastic consequences in real world situations, but they also reveal much about the underlying mechanisms of motion perception. Here we show that motion signals suppressed from awareness can warp simultaneous conscious speed perception. In Experiment 1, we measured global speed discrimination thresholds using an annulus of 8 local Gabor elements. We show that physically removing local elements from the array attenuated global speed discrimination. However, removing awareness of the local elements only had a small effect on speed discrimination. That is, unconscious local motion elements contributed to global conscious speed perception. In Experiment 2 we measured the global speed of the moving Gabor patterns, when half the elements moved at different speeds. We show that global speed averaging occurred regardless of whether local elements were removed from awareness, such that the speed of invisible elements continued to be averaged together with the visible elements to determine the global speed. These data suggest that contextual motion signals outside of awareness can both boost and affect our experience of motion speed, and suggest that such pooling of motion signals occurs before the conscious extraction of the surround motion speed.

  1. Entrepreneurship Teaching Conducted as Strategic Reflexive Conversation

    DEFF Research Database (Denmark)

    Kristiansson, Michael

    The paper intends exploring and ascertaining whether the concept of strategic reflexive conversation can profitably be applied to entrepreneurship. As a start, a process of conceptualisation is undertaken, which is instrumental in placing the notion of strategic reflexive conversation...... into a knowledge management perspective. Strategic reflexive conversation is presented in an enhanced and updated version, which is contrasted to entrepreneurship through reflection. The findings indicate and it can be concluded that, with some important reservations, strategic reflexive conversation can...... and empirical studies. No doubt the reported study can be enhanced and refined in a theoretical sense and be empirically supported. The paper addresses a potentially significant theme and aims to stimulate discussion, which can provide input and ideas for enhancing practice-oriented entrepreneurship...

  2. Portraying Reflexivity in Health Services Research.

    Science.gov (United States)

    Rae, John; Green, Bill

    2016-09-01

    A model is proposed for supporting reflexivity in qualitative health research, informed by arguments from Bourdieu and Finlay. Bourdieu refers to mastering the subjective relation to the object at three levels-the overall social space, the field of specialists, and the scholastic universe. The model overlays Bourdieu's levels of objectivation with Finlay's three stages of research (pre-research, data collection, and data analysis). The intersections of these two ways of considering reflexivity, displayed as cells of a matrix, pose questions and offer prompts to productively challenge health researchers' reflexivity. Portraiture is used to show how these challenges and prompts can facilitate such reflexivity, as illustrated in a research project. © The Author(s) 2016.

  3. On the Second Language Acquisition of Spanish Reflexive Passives and Reflexive Impersonals by French- and English-Speaking Adults

    Science.gov (United States)

    Tremblay, Annie

    2006-01-01

    This study, a partial replication of Bruhn de Garavito (1999a; 1999b), investigates the second language (L2) acquisition of Spanish reflexive passives and reflexive impersonals by French- and English-speaking adults at an advanced level of proficiency. The L2 acquisition of Spanish reflexive passives and reflexive impersonals by native French and…

  4. Motion coherence and direction discrimination in healthy aging.

    Science.gov (United States)

    Pilz, Karin S; Miller, Louisa; Agnew, Hannah C

    2017-01-01

    Perceptual functions change with age, particularly motion perception. With regard to healthy aging, previous studies mostly measured motion coherence thresholds for coarse motion direction discrimination along cardinal axes of motion. Here, we investigated age-related changes in the ability to discriminate between small angular differences in motion directions, which allows for a more specific assessment of age-related decline and its underlying mechanisms. We first assessed older (>60 years) and younger (discriminate coarse horizontal (left/right) and vertical (up/down) motion at 100% coherence and a stimulus duration of 400 ms. In a second step, we determined participants' motion coherence thresholds for vertical and horizontal coarse motion direction discrimination. In a third step, we used the individually determined motion coherence thresholds and tested fine motion direction discrimination for motion clockwise away from horizontal and vertical motion. Older adults performed as well as younger adults for discriminating motion away from vertical. Surprisingly, performance for discriminating motion away from horizontal was strongly decreased. Further analyses, however, showed a relationship between motion coherence thresholds for horizontal coarse motion direction discrimination and fine motion direction discrimination performance in older adults. In a control experiment, using motion coherence above threshold for all conditions, the difference in performance for horizontal and vertical fine motion direction discrimination for older adults disappeared. These results clearly contradict the notion of an overall age-related decline in motion perception, and, most importantly, highlight the importance of taking into account individual differences when assessing age-related changes in perceptual functions.

  5. Visual motion detection sensitivity is enhanced by an orthogonal motion aftereffect.

    Science.gov (United States)

    Takemura, Hiromasa; Murakami, Ikuya

    2010-09-09

    A recent study (H. Takemura & I. Murakami, 2010) showed enhancement of motion detection sensitivity by an orthogonal induced motion, suggesting that a weak motion component can combine with an orthogonal motion component to generate stronger oblique motion perception. Here we examined how an orthogonal motion aftereffect (MAE) affects motion detection sensitivity. After adaptation to vertical motion, a Gabor patch barely moving leftward or rightward was presented. As a result of an interaction between horizontal physical motion and a vertical MAE, subjects perceived the stimulus as moving obliquely. Subjects were asked to judge the horizontal direction of motion irrespective of the vertical MAE. The performance was enhanced when the Gabor patch was perceived as moving obliquely as the result of a weak MAE. The enhancement effect depended on the strength of the MAE for each subject rather than on the temporal frequency of the adapting stimulus. These results suggest that weak motion information that is hard to detect can interact with orthogonal adaptation and yield stronger oblique motion perception, making directional judgment easier. Moreover, the present results indicate that the enhancement effect of orthogonal motion involves general motion integration mechanisms rather than a specific mechanism only applicable to a particular type of illusory motion.

  6. Reflexive convention: civil partnership, marriage and family.

    Science.gov (United States)

    Heaphy, Brian

    2017-09-14

    Drawing on an analysis of qualitative interview data from a study of formalized same-sex relationships (civil partnerships) this paper examines the enduring significance of marriage and family as social institutions. In doing so, it intervenes in current debates in the sociology of family and personal life about how such institutions are undermined by reflexivity or bolstered by convention. Against the backdrop of dominating sociological frames for understanding the links between the changing nature of marriage and family and same-sex relationship recognition, the paper analyses the diverse and overlapping ways (including the simple, relational, strategic, ambivalent and critical ways) in which same-sex partners reflexively constructed and engaged with marriage and family conventions. My analysis suggests that instead of viewing reflexivity and convention as mutually undermining, as some sociologists of family and personal life do, it is insightful to explore how diverse forms of reflexivity and convention interact in everyday life to reconfigure the social institutions of marriage and family, but do not undermine them as such. I argue the case for recognizing the ways in which 'reflexive convention', or reflexive investment in convention, contributes to the continuing significance of marriage and family as social institutions. © London School of Economics and Political Science 2017.

  7. The passive of reflexive verbs in Icelandic

    Directory of Open Access Journals (Sweden)

    Hlíf Árnadóttir

    2011-10-01

    Full Text Available The Reflexive Passive in Icelandic is reminiscent of the so-called New Passive (or New Impersonal in that the oblique case of a passivized object NP is preserved. As is shown by recent surveys, however, speakers who accept the Reflexive Passive do not necessarily accept the New Passive, whereas conversely, speakers who accept the New Passive do also accept the Reflexive Passive. Based on these results we suggest that there is a hierarchy in the acceptance of passive sentences in Icelandic, termed the Passive Acceptability Hierarchy. The validity of this hierarchy is confirmed by our diachronic corpus study of open access digital library texts from Icelandic journals and newspapers dating from the 19th and 20th centuries (tímarit.is. Finally, we sketch an analysis of the Reflexive Passive, proposing that the different acceptability rates of the Reflexive and New Passives lie in the argument status of the object. Simplex reflexive pronouns are semantically dependent on the verbs which select them, and should therefore be analyzed as syntactic arguments only, and not as semantic arguments of these verbs.

  8. Torso flexion modulates stiffness and reflex response.

    Science.gov (United States)

    Granata, K P; Rogers, E

    2007-08-01

    Neuromuscular factors that contribute to spinal stability include trunk stiffness from passive and active tissues as well as active feedback from reflex response in the paraspinal muscles. Trunk flexion postures are a recognized risk factor for occupational low-back pain and may influence these stabilizing control factors. Sixteen healthy adult subjects participated in an experiment to record trunk stiffness and paraspinal muscle reflex gain during voluntary isometric trunk extension exertions. The protocol was designed to achieve trunk flexion without concomitant influences of external gravitational moment, i.e., decouple the effects of trunk flexion posture from trunk moment. Systems identification analyses identified reflex gain by quantifying the relation between applied force disturbances and time-dependent EMG response in the lumbar paraspinal muscles. Trunk stiffness was characterized from a second order model describing the dynamic relation between the force disturbances versus the kinematic response of the torso. Trunk stiffness increased significantly with flexion angle and exertion level. This was attributed to passive tissue contributions to stiffness. Reflex gain declined significantly with trunk flexion angle but increased with exertion level. These trends were attributed to correlated changes in baseline EMG recruitment in the lumbar paraspinal muscles. Female subjects demonstrated greater reflex gain than males and the decline in reflex gain with flexion angle was greater in females than in males. Results reveal that torso flexion influences neuromuscular factors that control spinal stability and suggest that posture may contribute to the risk of instability injury.

  9. New motion illusion caused by pictorial motion lines.

    Science.gov (United States)

    Kawabe, Takahiro; Miura, Kayo

    2008-01-01

    Motion lines (MLs) are a pictorial technique used to represent object movement in a still picture. This study explored how MLs contribute to motion perception. In Experiment 1, we reported the creation of a motion illusion caused by MLs: random displacements of objects with MLs on each frame were perceived as unidirectional global motion along the pictorial motion direction implied by MLs. In Experiment 2, we showed that the illusory global motion in the peripheral visual field captured the perceived motion direction of random displacement of objects without MLs in the central visual field, and confirmed that the results in Experiment 1 did not stem simply from response bias, but resulted from perceptual processing. In Experiment 3, we showed that the spatial arrangement of orientation information rather than ML length is important for the illusory global motion. Our results indicate that the ML effect is based on perceptual processing rather than response bias, and that comparison of neighboring orientation components may underlie the determination of pictorial motion direction with MLs.

  10. Optokinetic and vestibulo-ocular reflex responses to an unpredictable stimulus

    Science.gov (United States)

    Peterka, Robert J.; Black, F. Owen; Schoenhoff, Monika B.

    1987-01-01

    Horizontal plane optokinetic (OKR) and vestibuloocular reflex eye movements were obtained from normal subjects in response to pseudorandom rotational stimulation. Results showed large intersubject variability in OKR responses. Typical OKR responses had approximately constant gain over 0.02-1.5 Hz. Response phase was near zero below 0.1 Hz with increasing phase lags as frequency increased consistent with time delays of 180 ms. Results suggested that visual motion information could be significant in the control of eye movements up to 6.1 Hz. Pseudorandom optokinetic stimulation induced motion sickness symptoms in approximately 20 percent of the 213 subjects tested.

  11. Multisensory Control of Stabilization Reflexes

    Science.gov (United States)

    2012-08-22

    direction of motion sensitive neurons. In: Rhythmogenesis in Neurons and Networks. Eds. N. Elsner, D.W. Richter, Thieme , Stuttgart 1992, 306. A2. Krapp H...Eds. N. Elsner, M. Heisenberg, Thieme , Stuttgart 1993, 357. A3. Krapp H., Hengstenberg B., and Hengstenberg R.: Correspondence of dendritic field...Göttingen Neurobiology Conference, Vol. II. Eds. N. Elsner, H. Breer, Thieme , Stuttgart 1994, 447. A4. Krapp H. and Hengstenberg R.: Comparison

  12. Elbow spasticity during passive stretch-reflex: clinical evaluation using a wearable sensor system

    Science.gov (United States)

    2013-01-01

    Background Spasticity is a prevalent chronic condition among persons with upper motor neuron syndrome that significantly impacts function and can be costly to treat. Clinical assessment is most often performed with passive stretch-reflex tests and graded on a scale, such as the Modified Ashworth Scale (MAS). However, these scales are limited in sensitivity and are highly subjective. This paper shows that a simple wearable sensor system (angle sensor and 2-channel EMG) worn during a stretch-reflex assessment can be used to more objectively quantify spasticity in a clinical setting. Methods A wearable sensor system consisting of a fibre-optic goniometer and 2-channel electromyography (EMG) was used to capture data during administration of the passive stretch-reflex test for elbow flexor and extensor spasticity. A kinematic model of unrestricted passive joint motion was used to extract metrics from the kinematic and EMG data to represent the intensity of the involuntary reflex. Relationships between the biometric results and clinical measures (MAS, isometric muscle strength and passive range of motion) were explored. Results Preliminary results based on nine patients with varying degrees of flexor and extensor spasticity showed that kinematic and EMG derived metrics were strongly correlated with one another, were correlated positively (and significantly) with clinical MAS, and negatively correlated (though mostly non-significant) with isometric muscle strength. Conclusions We conclude that a wearable sensor system used in conjunction with a simple kinematic model can capture clinically relevant features of elbow spasticity during stretch-reflex testing in a clinical environment. PMID:23782931

  13. Soleus H-Reflex Operant Conditioning Changes The H-Reflex Recruitment Curve

    Science.gov (United States)

    Thompson, Aiko K.; Chen, Xiang Yang; Wolpaw, Jonathan R.

    2012-01-01

    Introduction Operant conditioning can gradually change the human soleus H-reflex. The protocol conditions the reflex near M-wave threshold. This study examined its impact on the reflexes at other stimulus strengths. Methods H-reflex recruitment curves were obtained before and after a 24-session exposure to an up-conditioning (HRup) or down-conditioning (HRdown) protocol and were compared. Results In both HRup and HRdown subjects, conditioning affected the entire H-reflex recruitment curve. In 5 of 6 HRup and 3 of 6 HRdown subjects, conditioning elevated (HRup) or depressed (HRdown), respectively, the entire curve. In the other HRup subject or the other 3 HRdown subjects, the curve was shifted to the left or to the right, respectively. Discussion H-reflex conditioning does not simply change the H-reflex to a stimulus of particular strength; it also changes the H-reflexes to stimuli of different strengths. Thus, it is likely to affect many actions in which this pathway participates. PMID:23281107

  14. Loading and reflexes : the influence of body weight and active movements on reflex responses in humans

    NARCIS (Netherlands)

    Bastiaanse, Catharina Maria

    2003-01-01

    This thesis describes six studies on the influence of active movements and body loading on reflex responses. To measure those influences healthy subjects were asked to walk with different loadings (e.g. a backpack) or with different active movements (e.g. arm swing) while different reflex responses

  15. The trigemino-cervical reflex in normal subjects.

    Science.gov (United States)

    Milanov, I; Bogdanova, D; Ishpekova, B

    2001-01-01

    There are only few reports on the trigemino-cervical reflex in humans and there is debate over the best method of reflex examination. The aim of this study was, comparing different methods, to provide a reproducible method for evaluating the trigemino-cervical reflex. The trigemino-cervical reflex was studied in 32 healthy volunteers. The stimulation was applied to the supraorbital, infraorbital or mental nerve. Recordings were performed bilaterally from the sternocleidomastoid and trapezius muscles at rest. The reflex was also examined during maximal voluntary contraction of the sternocleidomastoid muscle after supraorbital nerve stimulation. It presented as a two-component reflex if recorded from a tonically active muscle and as a one-component reflex if recorded from a relaxed muscle. The most reproducible reflex responses were obtained from the resting sternocleidomastoid muscle after stimulation of the supraorbital nerve. In conclusion, the trigemino-cervical reflex may be most easily obtained from the relaxed sternocleidomastoid muscle after supraorbital nerve stimulation.

  16. The effect of visual apparent motion on audiovisual simultaneity.

    Science.gov (United States)

    Kwon, Jinhwan; Ogawa, Ken-ichiro; Miyake, Yoshihiro

    2014-01-01

    Visual motion information from dynamic environments is important in multisensory temporal perception. However, it is unclear how visual motion information influences the integration of multisensory temporal perceptions. We investigated whether visual apparent motion affects audiovisual temporal perception. Visual apparent motion is a phenomenon in which two flashes presented in sequence in different positions are perceived as continuous motion. Across three experiments, participants performed temporal order judgment (TOJ) tasks. Experiment 1 was a TOJ task conducted in order to assess audiovisual simultaneity during perception of apparent motion. The results showed that the point of subjective simultaneity (PSS) was shifted toward a sound-lead stimulus, and the just noticeable difference (JND) was reduced compared with a normal TOJ task with a single flash. This indicates that visual apparent motion affects audiovisual simultaneity and improves temporal discrimination in audiovisual processing. Experiment 2 was a TOJ task conducted in order to remove the influence of the amount of flash stimulation from Experiment 1. The PSS and JND during perception of apparent motion were almost identical to those in Experiment 1, but differed from those for successive perception when long temporal intervals were included between two flashes without motion. This showed that the result obtained under the apparent motion condition was unaffected by the amount of flash stimulation. Because apparent motion was produced by a constant interval between two flashes, the results may be accounted for by specific prediction. In Experiment 3, we eliminated the influence of prediction by randomizing the intervals between the two flashes. However, the PSS and JND did not differ from those in Experiment 1. It became clear that the results obtained for the perception of visual apparent motion were not attributable to prediction. Our findings suggest that visual apparent motion changes temporal

  17. Using ESO Reflex with Web Services

    Science.gov (United States)

    Järveläinen, P.; Savolainen, V.; Oittinen, T.; Maisala, S.; Ullgrén, M. Hook, R.

    2008-08-01

    ESO Reflex is a prototype graphical workflow system, based on Taverna, and primarily intended to be a flexible way of running ESO data reduction recipes along with other legacy applications and user-written tools. ESO Reflex can also readily use the Taverna Web Services features that are based on the Apache Axis SOAP implementation. Taverna is a general purpose Web Service client, and requires no programming to use such services. However, Taverna also has some restrictions: for example, no numerical types such integers. In addition the preferred binding style is document/literal wrapped, but most astronomical services publish the Axis default WSDL using RPC/encoded style. Despite these minor limitations we have created simple but very promising test VO workflow using the Sesame name resolver service at CDS Strasbourg, the Hubble SIAP server at the Multi-Mission Archive at Space Telescope (MAST) and the WESIX image cataloging and catalogue cross-referencing service at the University of Pittsburgh. ESO Reflex can also pass files and URIs via the PLASTIC protocol to visualisation tools and has its own viewer for VOTables. We picked these three Web Services to try to set up a realistic and useful ESO Reflex workflow. They also demonstrate ESO Reflex abilities to use many kind of Web Services because each of them requires a different interface. We describe each of these services in turn and comment on how it was used

  18. Eye movements to yaw, pitch, and roll about vertical and horizontal axes : Adaptation, and motion sickness

    NARCIS (Netherlands)

    Bos, J.E.; Bles, W.; Graaf, B. de

    2002-01-01

    Background: In the search for parameters to predict motion sickness that can be measured in the laboratory, we performed a longitudinal investigation in aviators. Since the vestibular system is involved in the generation of motion sickness as well as eye movements, vestibulo-ocular reflex (VOR) para

  19. The stretch reflex and the contributions of C David Marsden

    Directory of Open Access Journals (Sweden)

    Kalyan B Bhattacharyya

    2017-01-01

    Full Text Available The stretch reflex or myotatic reflex refers to the contraction of a muscle in response to its passive stretching by increasing its contractility as long as the stretch is within physiological limits. For ages, it was thought that the stretch reflex was of short latency and it was synonymous with the tendon reflex, subserving the same spinal reflex arc. However, disparities in the status of the two reflexes in certain clinical situations led Marsden and his collaborators to carry out a series of experiments that helped to establish that the two reflexes had different pathways. That the two reflexes are dissociated has been proved by the fact that the stretch reflex and the tendon reflex, elicited by stimulation of the same muscle, have different latencies, that of the stretch reflex being considerably longer. They hypothesized that the stretch reflex had a transcortical course before it reached the spinal motor neurons for final firing. Additionally, the phenomenon of stimulus-sensitive cortical myoclonus lent further evidence to the presence of the transcortical loop where the EEG correlate preceded the EMG discharge. This concept has been worked out by later neurologists in great detail , and the general consensus is that indeed, the stretch reflex is endowed with a conspicuous transcortical component.

  20. The effect of elbow position on biceps tendon reflex

    Directory of Open Access Journals (Sweden)

    Keles Isik

    2004-07-01

    Full Text Available Background: Testing of tendon (T reflex is the basic method used in the diagnostic procedure of clinical neurology. Measurement of T reflexes precisely can be a valuable adjunct to clinical examination. Quantification of T reflexes may provide more accurate results. Aims: To analyze the effect of elbow position on biceps T reflex. Settings and Design: A self-controlled clinical trial of biceps T reflex testing at the Electrophysiology Unit of the Department of Physical Medicine and Rehabilitation. Methods and Materials: Biceps T reflex was obtained utilizing a hand-held electronic reflex hammer in 50 extremities of 25 healthy volunteers and the effect of elbow position (at 90°, 120° and 150° on reflex response was evaluated. Statistical Analysis: Repeated-measures analysis of variance by the General Linear Model and Pearson correlation test procedures. Results: Onset latency was significantly shorter at 120° of elbow position. The maximum amplitude value of biceps T reflex was obtained at 90° of elbow position. Onset latency of the reflex correlated significantly with the height and arm length but not with age. Conclusions: The electrophysiological measurement of T reflexes is an easy and useful method in the quantification of reflexes, supplying more objective data. However, when performing T reflex studies, the position of the extremity should be taken into consideration to achieve more reliable results.

  1. Wipe and flexion reflexes of the frog. II. Response to perturbations.

    Science.gov (United States)

    Schotland, J L; Rymer, W Z

    1993-05-01

    relations during flexion withdrawal. 4. Despite the addition of an external load, all animals successfully and reliably removed the stimulus during the wipe reflex, and the relative timing of both the EMG pattern and joint angle motion was preserved. 5. Immediately after section of the nerve to a single muscle (iliofibularis), all animals successfully and reliably removed the stimulus during the wipe reflex. The relative timing of muscle activation was preserved, accompanied by a reduction in the activity level of gluteus magnus, a muscle with action reciprocal to iliofibularis.(ABSTRACT TRUNCATED AT 400 WORDS)

  2. Reflexive Planning as Design and Work

    DEFF Research Database (Denmark)

    Lissandrello, Enza; Grin, John

    2011-01-01

    In recent years, planning theorists have advanced various interpretations of the notion of reflexivity, inspired by American pragmatism, complexity theory, hermeneutics, discursive and collaborative planning. Scholars agree that “reflexivity” has a strong temporal dimension: it not only aims...... to solve present planning problems, but to imagine and understand alternative trajectories for future action. This article explores the practical utility of reflexivity for planners, through a case study that focuses on a project to promote sustainable development in the Port of Amsterdam. Reflexivity...... in planning emerges as a new tool for generating critical knowledge and dialogue that can synthesise the perspectives of multiple actors in a common understanding, existing structural constraints and a collective imagination of alternative future possibilities. Such research highlights the potential...

  3. Human investigations into the exercise pressor reflex

    DEFF Research Database (Denmark)

    Secher, Niels H; Amann, Markus

    2012-01-01

    During exercise, neural input from skeletal muscles reflexly maintains or elevates blood pressure (BP) despite a maybe fivefold increase in vascular conductance. This exercise pressor reflex is illustrated by similar heart rate (HR) and BP responses to electrically induced and voluntary exercise....... The importance of the exercise pressor reflex for tight cardiovascular regulation during dynamic exercise is supported by studies using pharmacological blockade of lower limb muscle afferent nerves. These experiments show attenuation of the increase in BP and cardiac output when exercise is performed...... of an increase in BP during exercise with paralysed legs manifests, although electrical stimulation of muscles enhances lactate release and reduces muscle glycogen. Thus, the exercise pressor reflex enhances sympathetic activity and maintains perfusion pressure by restraining abdominal blood flow, while brain...

  4. Reflexive Planning as Design and Work

    DEFF Research Database (Denmark)

    Lissandrello, Enza; Grin, John

    2011-01-01

    In recent years, planning theorists have advanced various interpretations of the notion of reflexivity, inspired by American pragmatism, complexity theory, hermeneutics, discursive and collaborative planning. Scholars agree that “reflexivity” has a strong temporal dimension: it not only aims...... to solve present planning problems, but to imagine and understand alternative trajectories for future action. This article explores the practical utility of reflexivity for planners, through a case study that focuses on a project to promote sustainable development in the Port of Amsterdam. Reflexivity...... in planning emerges as a new tool for generating critical knowledge and dialogue that can synthesise the perspectives of multiple actors in a common understanding, existing structural constraints and a collective imagination of alternative future possibilities. Such research highlights the potential...

  5. Reflexive structures an introduction to computability theory

    CERN Document Server

    Sanchis, Luis E

    1988-01-01

    Reflexive Structures: An Introduction to Computability Theory is concerned with the foundations of the theory of recursive functions. The approach taken presents the fundamental structures in a fairly general setting, but avoiding the introduction of abstract axiomatic domains. Natural numbers and numerical functions are considered exclusively, which results in a concrete theory conceptually organized around Church's thesis. The book develops the important structures in recursive function theory: closure properties, reflexivity, enumeration, and hyperenumeration. Of particular interest is the treatment of recursion, which is considered from two different points of view: via the minimal fixed point theory of continuous transformations, and via the well known stack algorithm. Reflexive Structures is intended as an introduction to the general theory of computability. It can be used as a text or reference in senior undergraduate and first year graduate level classes in computer science or mathematics.

  6. Orthodoxy and reflexivity in international comparative analysis

    DEFF Research Database (Denmark)

    Lind, Jens; Valkenburg, Ben

    2002-01-01

    project, in which we have tried to deal with these consequences. Fourth, and hopefully as a result of the first three aims, we want to argue that a reflexive approach of international, comparative research is not only desirable, but attainable as well. In order to do so, we begin with a short discussion...... upon the consequences on the level of empirical research. We want to avoid that, so our second and third subject will be the practical implications of reflexivity for empirical research as well as for social policy. Our discussion on these subjects is based on the practical experiences in the INPART...... on the main issues in the so-called ?reflexive approach? and consider the main consequences of this approach for both social science and social policy. Against this background we will discuss the implications for comparative research and the experiences of the INPART project end up with a few central issues...

  7. Three-dimensional anorthoscopic perception.

    Science.gov (United States)

    Fujita, N

    1990-01-01

    When a rotating 3-D wireframe object passes behind a narrow slit, it is often perceived as a 3-D object, even though only a small portion of it is visible at any one instant. This result constitutes a new finding in connection with both anorthoscopic perception and the perception of structure-from-motion.

  8. Motion transparency arises from perceptual grouping: evidence from luminance and contrast modulation motion displays.

    Science.gov (United States)

    McOwan, P W; Johnston, A

    1996-10-01

    What circumstance lead to the perception of global motion transparency? it has been shown that, in paired random dot displays, motion transparency can be abolished if the separation of the dot pairs is sufficiently small. Motion transparency has also been shown to be influenced by high level cognitive cues. Here, we report that the combination of two moving dot stimuli, which separately invoke a percept of transparent motion, gives rise to a non-transparent percept of local rotation. These stimuli were constructed using various different pattern elements, including luminance defined elements and contrast modulations. The results extend and support the view that high-level grouping of local measures of the velocity field can determine whether a motion transparency is perceived or not.

  9. New molecular knowledge towards the trigemino-cardiac reflex as a cerebral oxygen-conserving reflex.

    Science.gov (United States)

    Sandu, N; Spiriev, T; Lemaitre, F; Filis, A; Schaller, B

    2010-05-04

    The trigemino-cardiac reflex (TCR) represents the most powerful of the autonomous reflexes and is a subphenomenon in the group of the so-called "oxygen-conserving reflexes". Within seconds after the initiation of such a reflex, there is a powerful and differentiated activation of the sympathetic system with subsequent elevation in regional cerebral blood flow (CBF), with no changes in the cerebral metabolic rate of oxygen (CMRO2) or in the cerebral metabolic rate of glucose (CMRglc). Such an increase in regional CBF without a change of CMRO2 or CMRglc provides the brain with oxygen rapidly and efficiently. Features of the reflex have been discovered during skull base surgery, mediating reflex protection projects via currently undefined pathways from the rostral ventrolateral medulla oblongata to the upper brainstem and/or thalamus, which finally engage a small population of neurons in the cortex. This cortical center appears to be dedicated to transduce a neuronal signal reflexively into cerebral vasodilatation and synchronization of electrocortical activity; a fact that seems to be unique among autonomous reflexes. Sympathetic excitation is mediated by cortical-spinal projection to spinal preganglionic sympathetic neurons, whereas bradycardia is mediated via projections to cardiovagal motor medullary neurons. The integrated reflex response serves to redistribute blood from viscera to the brain in response to a challenge to cerebral metabolism, but seems also to initiate a preconditioning mechanism. Previous studies showed a great variability in the human TCR response, in special to external stimuli and individual factors. The TCR gives, therefore, not only new insights into novel therapeutic options for a range of disorders characterized by neuronal death, but also into the cortical and molecular organization of the brain.

  10. Stuttering or reflex seizure? A case report.

    Science.gov (United States)

    Michel, Véronique; Burbaud, Pierre; Taillard, Jacques; Gaida, Tsouria; Joseph, Pierre Alain; Duché, Bernard; Bioulac, Bernard

    2004-09-01

    Stuttering is characterized by involuntary syllabic repetitions and interruption in the smooth flow of speech. The exact cause of primary stuttering remains a matter of debate but a frontal dysfunction has been evoked. On the other hand, acquired stuttering is uncommon. We report a case of reflex epilepsy in which seizures were triggered by reading aloud or stressful conversation. Each paroxysmal event in left frontal region was associated clinically with a language disorder mimicking stuttering. Our observation suggests that reflex frontal focal epilepsy could be a putative etiology for acquired stuttering.

  11. [The vegetative component of a conditioned reflex].

    Science.gov (United States)

    Ordzhonikadze, Ts A; Pkhakadze, L D

    1975-01-01

    Defensive and alimentary conditioned reflexes were studied on normal cats and cats with neural isolation of the neocortex. The cardiac component of the conditioned reflexes is elaborated in decorticated animals at a similar rate and is as steady as in normal cats. Motor conditioned reactions in decorticated cats are difficult to elaborate. Both in normal and decorticated cats unconditioned pain stimulation evokes tachycardia, while a conditioned signal, paired with this unconditioned stimulus, produces bradicardia. Ban assumption has been made that the primary conditioned reaction consists in the appearance of a certain emotional state which changes the cardiac rhythm in a typical way.

  12. Charitable giving and reflexive individuals: How personal reflexivity mediates between structure and agency.

    Science.gov (United States)

    Sanghera, Balihar

    2017-03-01

    This article examines how individuals are reflexive beings who interpret the world in relation to things that matter to them, and how charitable acts are evaluated and embedded in their lives with different degrees of meaning and importance. Rather than framing the discussion of charitable practices in terms of an altruism/egoism binary or imputing motivations and values to social structures, the article explains how reflexivity is an important and neglected dimension of social practices, and how it interacts with sympathy, sentiments and discourses to shape giving. The study also shows that there are different modes of reflexivity, which have varied effects on charity and volunteering.

  13. How many theta roles in a reflexive verb?

    NARCIS (Netherlands)

    Dimitriadis, Alexis; Everaert, Martin

    2014-01-01

    While purely syntactic approaches to reflexivization have characterized reflexive verbs in terms of detransitivization, we show that there is a discrepancy between syntactic and semantic arity. Reflexive verbs are syntactically intransitive, but semantically they are two-place predicates: both

  14. Team Reflexivity and Innovation: The Moderating Role of Team Context

    OpenAIRE

    Dawson, J.; Schippers, M; M. West

    2012-01-01

    Team reflexivity, the extent to which teams collectively reflect upon and adapt their working methods and functioning, has been shown to be an important predictor of team outcomes, notably innovation. As described in the current article, the authors developed and tested a team-level contingency model of team reflexivity, work demands, and innovation. They argue that highly reflexive teams will be more innovative than teams low in reflexivity when facing a demanding work environment. A field s...

  15. Control of reflexive saccades following hemispherectomy.

    Science.gov (United States)

    Reuter-Lorenz, Patricia A; Herter, Troy M; Guitton, Daniel

    2011-06-01

    Individuals who have undergone hemispherectomy for treatment of intractable epilepsy offer a rare and valuable opportunity to examine the ability of a single cortical hemisphere to control oculomotor performance. We used peripheral auditory events to trigger saccades, thereby circumventing dense postsurgical hemianopia. In an antisaccade task, patients generated numerous unintended short-latency saccades toward contralesional auditory events, indicating pronounced limitations in the ability of a single hemicortex to exert normal inhibitory control over ipsilateral (i.e., contralesional) reflexive saccade generation. Despite reflexive errors, patients retained an ability to generate correct antisaccades in both directions. The prosaccade task revealed numerous contralesional express saccades, a robust contralesional gap effect, but the absence of both effects for ipsilesional saccades. These results indicate limits to the saccadic control capabilities following hemispherectomy: A single hemicortex can mediate antisaccades in both directions, but plasticity does not extend fully to the bilateral inhibition of reflexive saccades. We posit that these effects are due to altered control dynamics that reduce the responsivity of the superior colliculus on the intact side and facilitate the release of an auditory-evoked ocular grasp reflex into the blind hemifield that the intact hemicortex has difficulty suppressing.

  16. Dilemmas and Deliberations in Reflexive Ethnographic Research

    Science.gov (United States)

    Robinson, Janean Valerie

    2014-01-01

    This paper traces insights into the challenges and dilemmas experienced whilst researching students' interpretations and understandings of the Behaviour Management in Schools policy in Western Australia. Journal records, supported by student transcripts, are woven together in a reflexive ethnographic journey--from the beginning phase of…

  17. The Reflexive Modernization of Australian Universities

    Science.gov (United States)

    Pick, David

    2004-01-01

    The profound changes occurring in Australian higher education are viewed here in the context of the social, cultural, political and economic effects of globalization. Particular attention is paid to providing a theoretical foundation for understanding these effects using the reflexive modernization perspective. Highlighted are some of the…

  18. A reflexive perspective in problem solving

    Directory of Open Access Journals (Sweden)

    Chio, José Angel

    2013-01-01

    Full Text Available The objective of this paper is to favour the methodological process of reflexive analysis in problem solving in the general teaching methods that concentrates in strengthening the dimensional analysis, to gain a greater preparation of the students for the solution of mathematical problems.

  19. Taking Control of Reflexive Social Attention

    Science.gov (United States)

    Ristic, Jelena; Kingstone, Alan

    2005-01-01

    Attention is shifted reflexively to where other people are looking. It has been argued by a number of investigators that this social attention effect reflects the obligatory bottom-up activation of domain-specific modules within the inferior temporal (IT) cortex that are specialized for processing face and gaze information. However, it is also the…

  20. The reflexive self and culture: a critique.

    Science.gov (United States)

    Adams, Matthew

    2003-06-01

    This article attempts to engage with a tendency in the theorization of social change and self-identity, evident in the work of a number of contemporary social theorists, to place an extended process of reflexivity at the heart of modern identity. As symptomatic of 'neo-modern' accounts of selfhood, critical readings of Giddens, Beck, Castells and some aspects of social theory more generally, and their account of modern reflexivity's relationship to culture, are assessed. In light of these criticisms, ways in which culture might still play an important part in the shaping of identity are considered. The relationship between language, culture and reflexivity, drawing from philosophy, sociology and G. H. Mead's own brand of social psychology, are all utilized in establishing a critique of the role Giddens and others designate for culture in the constitution of the contemporary self. By potentially repositioning self-identity in its connection to culture, the overall bearing of reflexivity upon the processes of self-identity is thus questioned. It is argued that a culturally-situated, yet fluid and multifarious account of self-identity is a necessary analytical and normative alternative.

  1. A Testbed for Autonomous Reflexive Grasping

    Science.gov (United States)

    1993-03-01

    written in C. The tactile sensor is neural network causes the reflex layer of the a 10 x 10 Tekscan sensor with an active area subsumption architecture to...Doctoral Thesis, March 1990. [9] J. G. Webster, Tactile Sensors for Robotics and Medicine, John Wiley & Sons, 1988 [10] Tekscan Inc., " Tekscan Corporate

  2. A Reflexive Model for Teaching Instructional Design.

    Science.gov (United States)

    Shambaugh, Neal; Magliaro, Susan

    2001-01-01

    Documents a five-year study of two instructors who collaborated on formally studying their teaching of a master's level instructional design course. Outlines their views on learning, teaching, and instructional design (ID), describes the ID course, and explains the reflexive instructional model used, in which the teachers examined their teaching…

  3. Artificial facial nerve reflex restores eyelid closure following orbicularis oculi muscle denervation

    Institute of Scientific and Technical Information of China (English)

    Yujuan Wang; Keyong Li; Jingquan Liu; Dongyue Xu; Yuefeng Rui; Chunsheng Yang

    2010-01-01

    To date, treatment of peripheral facial paralysis has focused on preservation of facial nerve integrity. However, with seriously damaged facial nerve cases, it is difficult to recover anatomical and functional integrity using present therapies. Therefore, the present study utilized artificial facial nerve reflex to obtain orbicularis oculi muscle (OOM) electromyography signals on the uninjured side through the use of implanted recording electrodes. The implanted electrical chips analyzed facial muscle motion on the uninjured side and triggered an electrical stimulator to emit current pulses, which resulted in stimulation of injured OOM contraction and maintained bilateral symmetry and consistency. Following signal recognition, extraction, and computer analysis, electromyography signals in the uninjured OOM resulted in complete eyelid closure, which was consistent with the voltage threshold for eye closure. These findings suggested that artificial facial nerve reflex through the use of implanted microelectronics in unilateral peripheral facial paralysis could restore eyelid closure following orbicularis oculi muscle denervation.

  4. New Molecular Knowledge Towards the Trigemino-Cardiac Reflex as a Cerebral Oxygen-Conserving Reflex

    Directory of Open Access Journals (Sweden)

    N. Sandu

    2010-01-01

    Full Text Available The trigemino-cardiac reflex (TCR represents the most powerful of the autonomous reflexes and is a subphenomenon in the group of the so-called “oxygen-conserving reflexes”. Within seconds after the initiation of such a reflex, there is a powerful and differentiated activation of the sympathetic system with subsequent elevation in regional cerebral blood flow (CBF, with no changes in the cerebral metabolic rate of oxygen (CMRO2 or in the cerebral metabolic rate of glucose (CMRglc. Such an increase in regional CBF without a change of CMRO2 or CMRglc provides the brain with oxygen rapidly and efficiently. Features of the reflex have been discovered during skull base surgery, mediating reflex protection projects via currently undefined pathways from the rostral ventrolateral medulla oblongata to the upper brainstem and/or thalamus, which finally engage a small population of neurons in the cortex. This cortical center appears to be dedicated to transduce a neuronal signal reflexively into cerebral vasodilatation and synchronization of electrocortical activity; a fact that seems to be unique among autonomous reflexes. Sympathetic excitation is mediated by cortical-spinal projection to spinal preganglionic sympathetic neurons, whereas bradycardia is mediated via projections to cardiovagal motor medullary neurons. The integrated reflex response serves to redistribute blood from viscera to the brain in response to a challenge to cerebral metabolism, but seems also to initiate a preconditioning mechanism. Previous studies showed a great variability in the human TCR response, in special to external stimuli and individual factors. The TCR gives, therefore, not only new insights into novel therapeutic options for a range of disorders characterized by neuronal death, but also into the cortical and molecular organization of the brain.

  5. The Interrater Reliability of Subjective Assessments of the Babinski Reflex.

    Science.gov (United States)

    Dafkin, Chloe; Green, Andrew; Kerr, Samantha; Veliotes, Demetri; Olivier, Benita; McKinon, Warrick

    2016-01-01

    The Babinski reflex is a clinical diagnostic tool; however, the interrater reliability of this tool is currently greatly contested. A comparison between rater groups with objective measurements of the Babinski reflex was therefore conducted. Fifteen recorded Babinski reflexes were assessed by 12 neurologists and 12 medical students as being either pathological or nonpathological. Kinematic and electromyographic variables were collected and used to assess which aspects of the Babinski reflex predict classification. Substantial interrater agreement within the neurologist and student groups (κ = .72 and .67, respectively) was shown; however, there were some differing aspects between what neurologists and students used to assess the reflex as determined by objective kinematic measurements.

  6. Specificity of reflex adaptation for task-relevant variability.

    Science.gov (United States)

    Franklin, David W; Wolpert, Daniel M

    2008-12-24

    The motor system responds to perturbations with reflexes, such as the vestibulo-ocular reflex or stretch reflex, whose gains adapt in response to novel and fixed changes in the environment, such as magnifying spectacles or standing on a tilting platform. Here we demonstrate a reflex response to shifts in the hand's visual location during reaching, which occurs before the onset of voluntary reaction time, and investigate how its magnitude depends on statistical properties of the environment. We examine the change in reflex response to two different distributions of visuomotor discrepancies, both of which have zero mean and equal variance across trials. Critically one distribution is task relevant and the other task irrelevant. The task-relevant discrepancies are maintained to the end of the movement, whereas the task-irrelevant discrepancies are transient such that no discrepancy exists at the end of the movement. The reflex magnitude was assessed using identical probe trials under both distributions. We find opposite directions of adaptation of the reflex response under these two distributions, with increased reflex magnitudes for task-relevant variability and decreased reflex magnitudes for task-irrelevant variability. This demonstrates modulation of reflex magnitudes in the absence of a fixed change in the environment, and shows that reflexes are sensitive to the statistics of tasks with modulation depending on whether the variability is task relevant or task irrelevant.

  7. Modulation of the initial light reflex during affective picture viewing.

    Science.gov (United States)

    Henderson, Robert R; Bradley, Margaret M; Lang, Peter J

    2014-09-01

    An initial reflexive constriction of the pupil to stimulation-the light reflex-is primarily modulated by brightness, but is attenuated when participants are under threat of shock (i.e., fear-inhibited light reflex). The present study assessed whether the light reflex is similarly attenuated when viewing emotional pictures. Pupil diameter was recorded while participants viewed erotic, violent, and neutral scenes that were matched in brightness; scrambled versions identical in brightness were also presented as an additional control. Compared to viewing neutral scenes, the light reflex was reliably modulated by hedonic content, with significant attenuation both when viewing unpleasant as well as pleasant pictures. No differences in the light reflex were found among scrambled versions. Thus, emotional modulation of the initial light reflex is not confined to a context of fear and is not indicative of brightness differences when viewing pictures of natural scenes. Copyright © 2014 Society for Psychophysiological Research.

  8. Can walking motions improve visually induced rotational self-motion illusions in virtual reality?

    Science.gov (United States)

    Riecke, Bernhard E; Freiberg, Jacob B; Grechkin, Timofey Y

    2015-02-04

    Illusions of self-motion (vection) can provide compelling sensations of moving through virtual environments without the need for complex motion simulators or large tracked physical walking spaces. Here we explore the interaction between biomechanical cues (stepping along a rotating circular treadmill) and visual cues (viewing simulated self-rotation) for providing stationary users a compelling sensation of rotational self-motion (circular vection). When tested individually, biomechanical and visual cues were similarly effective in eliciting self-motion illusions. However, in combination they yielded significantly more intense self-motion illusions. These findings provide the first compelling evidence that walking motions can be used to significantly enhance visually induced rotational self-motion perception in virtual environments (and vice versa) without having to provide for physical self-motion or motion platforms. This is noteworthy, as linear treadmills have been found to actually impair visually induced translational self-motion perception (Ash, Palmisano, Apthorp, & Allison, 2013). Given the predominant focus on linear walking interfaces for virtual-reality locomotion, our findings suggest that investigating circular and curvilinear walking interfaces offers a promising direction for future research and development and can help to enhance self-motion illusions, presence and immersion in virtual-reality systems.

  9. The human vertical translational vestibulo-ocular reflex. Normal and abnormal responses.

    Science.gov (United States)

    Liao, Ke; Walker, Mark F; Joshi, Anand; Reschke, Millard; Strupp, Michael; Leigh, R John

    2009-05-01

    Geometric considerations indicate that the human translational vestibulo-ocular reflex (tVOR) should have substantially different properties than the angular vestibulo-ocular reflex (aVOR). Specifically, tVOR cannot simultaneously stabilize images of distant and near objects on the retina. Most studies make the tacit assumption that tVOR acts to stabilize foveal images even though, in humans, tVOR is reported to compensate for less than 60% of foveal image motion. We have determined that the compensation gain (eye rotational velocity/required eye rotational velocity to maintain foveal target fixation) of tVOR is held steady at approximately 0.6 during viewing of either near or distant targets during vertical (bob) translations in ambient illumination. We postulate that tVOR evolved not to stabilize the image of the target on the fovea, but rather to minimize retinal image motion between objects lying in different depth planes, in order to optimize motion parallax information. Such behavior is optimized when binocular visual cues of both near and distant targets are available in ambient light. Patients with progressive supranuclear palsy or cerebellar ataxia show impaired ability to increase tVOR responses appropriately when they view near targets. In cerebellar patients, impaired ability to adjust tVOR responses to viewing conditions occurs despite intact ability to converge at near. Loss of the ability to adjust tVOR according to viewing conditions appears to represent a distinct disorder of vestibular function.

  10. Behavioral analysis of signals that guide learned changes in the amplitude and dynamics of the vestibulo-ocular reflex

    Science.gov (United States)

    Raymond, J. L.; Lisberger, S. G.

    1996-01-01

    We characterized the dependence of motor learning in the monkey vestibulo-ocular reflex (VOR) on the duration, frequency, and relative timing of the visual and vestibular stimuli used to induce learning. The amplitude of the VOR was decreased or increased through training with paired head and visual stimulus motion in the same or opposite directions, respectively. For training stimuli that consisted of simultaneous pulses of head and target velocity 80-1000 msec in duration, brief stimuli caused small changes in the amplitude of the VOR, whereas long stimuli caused larger changes in amplitude as well as changes in the dynamics of the reflex. When the relative timing of the visual and vestibular stimuli was varied, brief image motion paired with the beginning of a longer vestibular stimulus caused changes in the amplitude of the reflex alone, but the same image motion paired with a later time in the vestibular stimulus caused changes in the dynamics as well as the amplitude of the VOR. For training stimuli that consisted of sinusoidal head and visual stimulus motion, low-frequency training stimuli induced frequency-selective changes in the VOR, as reported previously, whereas high-frequency training stimuli induced changes in the amplitude of the VOR that were more similar across test frequency. The results suggest that there are at least two distinguishable components of motor learning in the VOR. One component is induced by short-duration or high-frequency stimuli and involves changes in only the amplitude of the reflex. A second component is induced by long-duration or low-frequency stimuli and involves changes in the amplitude and dynamics of the VOR.

  11. Behavioral analysis of signals that guide learned changes in the amplitude and dynamics of the vestibulo-ocular reflex

    Science.gov (United States)

    Raymond, J. L.; Lisberger, S. G.

    1996-01-01

    We characterized the dependence of motor learning in the monkey vestibulo-ocular reflex (VOR) on the duration, frequency, and relative timing of the visual and vestibular stimuli used to induce learning. The amplitude of the VOR was decreased or increased through training with paired head and visual stimulus motion in the same or opposite directions, respectively. For training stimuli that consisted of simultaneous pulses of head and target velocity 80-1000 msec in duration, brief stimuli caused small changes in the amplitude of the VOR, whereas long stimuli caused larger changes in amplitude as well as changes in the dynamics of the reflex. When the relative timing of the visual and vestibular stimuli was varied, brief image motion paired with the beginning of a longer vestibular stimulus caused changes in the amplitude of the reflex alone, but the same image motion paired with a later time in the vestibular stimulus caused changes in the dynamics as well as the amplitude of the VOR. For training stimuli that consisted of sinusoidal head and visual stimulus motion, low-frequency training stimuli induced frequency-selective changes in the VOR, as reported previously, whereas high-frequency training stimuli induced changes in the amplitude of the VOR that were more similar across test frequency. The results suggest that there are at least two distinguishable components of motor learning in the VOR. One component is induced by short-duration or high-frequency stimuli and involves changes in only the amplitude of the reflex. A second component is induced by long-duration or low-frequency stimuli and involves changes in the amplitude and dynamics of the VOR.

  12. Sensory Integration with Articulated Motion on a Humanoid Robot

    Directory of Open Access Journals (Sweden)

    J. Rojas

    2005-01-01

    Full Text Available This paper describes the integration of articulated motion with auditory and visual sensory information that enables a humanoid robot to achieve certain reflex actions that mimic those of people. Reflexes such as reach-and-grasp behavior enables the robot to learn, through experience, its own state and that of the world. A humanoid robot with binaural audio input, stereo vision, and pneumatic arms and hands exhibited tightly coupled sensory-motor behaviors in four different demonstrations. The complexity of successive demonstrations was increased to show that the reflexive sensory-motor behaviors combine to perform increasingly complex tasks. The humanoid robot executed these tasks effectively and established the groundwork for the further development of hardware and software systems, sensory-motor vector-space representations, and coupling with higher-level cognition.

  13. Reflexive regulation of CSR to promote sustainablility

    DEFF Research Database (Denmark)

    Buhmann, Karin

    climate change and environmental sustainability, and social, economic and other human rights lend human rights as part of CSR a potential for meeting some environmental and climate concerns and handling adverse side-effects. The article analyses two EU initiatives: The EU Multi-Stakeholder (MSF) on CSR...... in promoting companies’ responsibility with regard to aspects of sustainable development, such as climate impact. Keywords: Sustainable development, sustainable companies, reflexive regulation, climate change, CSR, EU law, public-private regulation, companies' self-regulation...... and the EU CSR Alliance. Focusing on human rights based in international law, it analyses the patterns of negotiation in the MSF and the background for the launch of the CSR Alliance. It shows that analysing public-private regulation of CSR from the perspective of reflexive law theory assists us...

  14. Reflexive cartography a new perspective in mapping

    CERN Document Server

    Casti, Emanuela

    2015-01-01

    Reflexive Cartography addresses the adaptation of cartography, including its digital forms (GIS, WebGIS, PPGIS), to the changing needs of society, and outlines the experimental context aimed at mapping a topological space. Using rigorous scientific analysis based on statement consistency, relevance of the proposals, and model accessibility, it charts the transition from topographical maps created by state agencies to open mapping produced by citizens. Adopting semiotic theory to uncover the complex communicative mechanisms of maps and to investigate their ability to produce their own messages and new perspectives, Reflexive Cartography outlines a shift in our way of conceptualizing maps: from a plastic metaphor of reality, as they are generally considered, to solid tools that play the role of agents, assisting citizens as they think and plan their own living place and make sense of the current world. Applies a range of technologies to theoretical perspectives on mapping to innovatively map the world's geogr...

  15. The Reflexive Principle of Sociological Theorization

    Directory of Open Access Journals (Sweden)

    R T Ubaidullayeva

    2013-12-01

    Full Text Available The article attempts to describe the reflexive principle in theory-making, which integrates the basic modern methodological paradigms and lays the foundation for the development of sociology. On the basis of the theoretical ideas of P. Bourdieu, A. Giddens and P. Ricoeur the author defines the concept of social reflexion and reveals its peculiarities in sociology as compared to reflexion in philosophy. According to the author, the fulfillment of reflexive functions in sociology is connected with the task of analyzing the complex structure of the polysemantic object, considering the specific quality of the subjects and their various trends of development. The presence of the poles — objectivity-subjectivity, rationality-irrationality, consciousness-unconsciousness etc, requires a reproduction of the dichotomies engendering them in social life and development of cognitive methods for their study in sociology.

  16. Tactile Sensing Reflexes for Advanced Prosthetic Hands

    Science.gov (United States)

    2016-10-01

    Quad Chart 37 1. INTRODUCTION: The purpose of this research is to equip a myoelectric prosthetic hand with contact detecting sensors and a...controller to perform contact detection reflex (11-13 mos.) 80% • Program controller to perform software functions for clinical studies (12-13 mos.) 60...candidates have been ordered, and are having pressure relief holes laser drilled . A custom flexible component board that holds the pressure sensor

  17. Visual Motion Perception and Visual Information Processing

    Science.gov (United States)

    1991-02-01

    ec B12 0 0 CL C. - d ef 112A 1/2 A 0.00 0.25 0.0 cm5 100 1/2 A + A 1(28 B High- Hgh Deleasons 1/28 1/28B Figure 5. Hypothetical and actual results of...UBI), Buys Ballot Laboratory, Utrecht University, Princetonplein 5, 3584 CC, Utrecht. The Netherlands. 2 Present address: Utrecht Biophysics Research...Institute (UBI), Buys Ballot Laboratory, Utrecht University, Princetonplein 5, 3584 CC, Utrecht, The Netherlands. 2 Abstract We present data on the

  18. Scrambled biological motion perception in patients with early-middle Parkinson disease%早中期帕金森患者的杂乱生物运动感知障碍

    Institute of Scientific and Technical Information of China (English)

    刘婷婷; 操瑞花; 胡盼盼; 田仰华; 陈先文; 汪凯

    2015-01-01

    目的:探讨帕金森病(Parkinson disease,PD)患者的杂乱生物运动感知能力。方法30例原发性PD患者以及与其人口学资料相匹配的正常对照组作为研究对象,采用生物运动的时距辨别任务(a duration dis⁃crimination task)进行杂乱生物运动感知能力测试。采用Hoehn-Yabr(H-Y)分级量表对PD患者的严重程度进行评定。结果与检验值“0”相比,正常对照组的主观相等点(the point of subjective equality, PSE)(-0.15±0.18)为负值,差异有统计学意义(t=4.56,P<0.001)。PD患者的PSE(0.04±0.21)与正常对照组的PSE相比,负值消失,差异有统计学意义(t=3.72, P<0.001)。PD 患者组按病情严重程度分为2亚组,PD早期组(H-Y 1~2级)的PSE (0.02±0.26)和PD中期组(H-Y 2.5~3级)的PSE(0.06±0.12)与正常对照组相比,差异均有统计学意义(PD早期组:P<0.01;PD中期组:P<0.01)。PD早期组和PD中期组的PSE之间无明显差异(P=0.61)。结论 PD患者在病程的早期即出现杂乱生物运动感知能力障碍,这种感知障碍可能与前额叶功能异常有关。%Objective To explore scrambled biological motion perception in Parkinson’s disease (PD). Meth⁃ods Thirty individuals with idiopathic PD and matched health controls (HCs) underwent discrimination task.The severi⁃ty of disease was assessed based on the Hohen and Yahr scale. Results Compared with“PSE=0”,there was a significant negative PSE (the point of subjective equality) (-0.15 ± 0.18) for HCs ( t=4.56, P<0.001), suggesting a temporal dilation effect of the upright scrambled biological motion sequences in HCs. There was a significant difference in the PSE be⁃tween PD patients(t=3.72,P<0.001) and HCs. Patients in the PD group were then divided into two subgroups accord⁃ing to their status of disease. There were significant differences in PSE between early-stage PD patients (stage 1-2) (0.02±0.26) and HCs

  19. Basic Gravitational Reflexes in the Larval Frog

    Science.gov (United States)

    Cochran, Stephen L.

    1996-01-01

    This investigation was designed to determine how a primitive vertebrate, the bullfrog tadpole, is able to sense and process gravitational stimuli. Because of the phylogenetic similarities of the vestibular systems in all vertebrates, the understanding of the gravitational reflexes in this relatively simple vertebrate should elucidate a skeletal framework on a elementary level, upon which the more elaborate reflexes of higher vertebrates may be constructed. The purpose of this study was to understand how the nervous system of the larval amphibian processes gravitational information. This study involved predominantly electrophysiological investigations of the isolated, alert (forebrain removed) bullfrog tadpole head. The focus of these experiments is threefold: (1) to understand from whole extraocular nerve recordings the signals sent to the eye following static gravitational tilt of the head; (2) to localize neuronal centers responsible for generating these signals through reversible pharmacological ablation of these centers; and (3) to record intracellularly from neurons within these centers in order to determine the single neuron's role in the overall processing of the center. This study has provided information on the mechanisms by which a primitive vertebrate processes gravitational reflexes.

  20. Acoustic reflex patterns in amyotrophic lateral sclerosis.

    Science.gov (United States)

    Canale, Andrea; Albera, Roberto; Lacilla, Michelangelo; Canosa, Antonio; Albera, Andrea; Sacco, Francesca; Chiò, Adriano; Calvo, Andrea

    2017-02-01

    The aim of the study is to investigate acoustic reflex testing in amyotrophic lateral sclerosis patients. Amplitude, latency, and rise time of stapedial reflex were recorded for 500 and 1000 Hz contralateral stimulus. Statistical analysis was performed by the Wilcoxon test and the level of significance was set at 5 %. Fifty-one amyotrophic lateral sclerosis patients and ten sex- and age-matched control subjects were studied. Patients were further divided in two groups: amyotrophic lateral sclerosis-bulbar (38 cases, with bulbar signs at evaluation) and amyotrophic lateral sclerosis-spinal (13 cases, without bulbar signs at evaluation). Stapedial reflex was present in all patients. There was a statistically significant difference in the mean amplitude, latency, and rise time between the amyotrophic lateral sclerosis patients as compared with the controls. Amplitude was lower in both the amyotrophic lateral sclerosis-bulbar and the amyotrophic lateral sclerosis-spinal patients than in the controls (p amyotrophic lateral sclerosis cases with bulbar signs and, moreover, suggesting a possible subclinical involvement of the stapedial motor neuron even in amyotrophic lateral sclerosis-spinal patients. Amplitude and rise time seem to be good sensitive parameters for investigating subclinical bulbar involvement.

  1. Social orienting: reflexive versus voluntary control.

    Science.gov (United States)

    Hill, Julia L; Patel, Saumil; Gu, Xue; Seyedali, Nassim S; Bachevalier, Jocelyne; Sereno, Anne B

    2010-09-24

    Many studies have shown that the direction of gaze of a face covertly facilitates the response to a target presented in the matching direction. In this study we seek to determine whether there exist separate reflexive and voluntary forms of such covert social orienting and how they interact with each other. We measured the effect of the predictive value of a gaze cue on manual choice reaction times. When the predictive value of the gaze cue was zero, a facilitatory cueing effect was still observed which peaked at a cue onset to target onset delay (CTD) of 150ms and largely diminished beyond a CTD of 500ms. When the gaze cue was 100% predictive of the future location of the target, at CTDs greater than 200, the predictive cue resulted in a significantly greater facilitation of response than occurred with a non-predictive cue. These results suggest that given enough time (about 200ms), the social cue is interpreted and a willful or voluntary spatially-specific social cueing effect occurs. In addition, we found that a predictive cue resulted in a significant slowing of the observer's responses up to a CTD of 200ms. These findings show that, similar to non-social spatial orienting, there appear to be two forms of social orienting including a reflexive component and voluntary component. We suggest a model of social orienting in which the voluntary social orienting system modulates tonic inhibition of the reflexive social orienting system. Published by Elsevier Ltd.

  2. Clinical correlation of cervical myelopathy and the hyperactive pectoralis reflex.

    Science.gov (United States)

    Paholpak, Permsak; Jirarattanaphochai, Kitti; Sae-Jung, Surachai; Wittayapairoj, Kriangkrai

    2013-12-01

    A diagnostic study. To validate the correlation between hyperactive pectoralis reflex and the level of cervical myelopathy. The hyperactive pectoralis reflex was proposed to be present in patients with spinal cord compression at the C2-3 and/or C3-4 level. Nevertheless, in a validation study on the correlation of various hyperactive reflexes and the cervical myelopathic level, this particular reflex was not evaluated. All patients presenting with cervical myelopathy between August 2009 and June 2012 were included in this study. Each patient underwent neurological examination for cervical myelopathy focusing on the examination of pathologic reflexes, including the hyperactive pectoralis reflex. We recorded the presence or absence of these reflexes and the level of cervical myelopathy as detected on magnetic resonance imaging. We used the level of spinal cord compression-cranial to C4 of the vertebral body-as the reference level to validate a hyperactive pectoralis reflex. The study included 95 cervical myelopathy patients: 33 patients had most of their compressed cervical cord somewhere above the C4 vertebral body. The hyperactive pectoralis reflex for cervical myelopathy at this level had a respective sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of 84.8%, 96.7%, 26.67, and 0.16. The high sensitivity and specificity of the hyperactive pectoralis reflex is very useful for screening and diagnosis of the cervical myelopathic level when it is above the C4 vertebral body.

  3. Motion transparency promotes synchronous perceptual binding.

    Science.gov (United States)

    Clifford, Colin W G; Spehar, Branka; Pearson, Joel

    2004-12-01

    While identified regions of human extrastriate visual cortex are functionally specialized for processing different attributes of an object, the cognitive and neural mechanisms by which these attributes are dynamically bound into integrated percepts are still largely mysterious. Here, we report that perceptual organization influences the dynamics of binding. Specifically, the perception of motion transparency promotes the synchronous perceptual binding of colour and motion, which otherwise exhibits considerable asynchronies. In addition, we demonstrate that perceptual asynchrony can be reinstated by manipulating stereoscopic disparity or speed within the stimulus. Our findings suggest that the phenomenology of colour-motion binding parallels the known physiology of motion processing in area MT of primate visual cortex, supporting the view that the dynamics of perceptual binding is a direct reflection of the time course of the underlying neural processing.

  4. Recording the trigemino-facial inhibitory reflex: technique and normal findings.

    Science.gov (United States)

    Cattaneo, Luigi; Pavesi, Giovanni

    2010-04-01

    The aim of this study was to propose a standardized technique for recording the trigemino-facial inhibitory reflex (TFIR) and to provide reference data of its components. The TFIR was recorded with concentric needle electrodes from the voluntarily activated depressor anguli oris muscle bilaterally in 26 healthy subjects (23-83 years). A vertical line was drawn from the corner of the mouth to the mandible margin, from which the needle insertion point was localized moving 1 to 2 cm upward and 1 to 2 cm laterally. The mentalis nerve was stimulated by surface electrodes at an intensity of 10x the perceptive threshold. The recovery cycle was studied at interstimulus intervals of 200, 350, and 500 milliseconds. The TFIR was constantly elicited in all participants. Upper normal limits (mean +/- 3 SD) of latency of the TFIR both ipsilateral and contralateral to stimulation were 65 milliseconds. Recovery of the reflex was of 71% at 200 milliseconds, 84% at 350 milliseconds, and 98% at 500 milliseconds interstimulus intervals. The recovery at the 200 milliseconds interstimulus intervals increased significantly with participant's age. The TFIR can be consistently and reliably recorded from the depressor anguli oris muscle using a standard technique. The reflex is robust showing complete recovery at 500 milliseconds interstimulus intervals.

  5. Reflexive and automatic violence: a function of aberrant perceptual inhibition

    Directory of Open Access Journals (Sweden)

    Golembiewski, Jan A.

    2014-12-01

    Full Text Available It is commonly assumed that psychiatric violence is motivated by delusions, but here the concept of a reversed impetus is explored, to understand whether delusions are formed as ad-hoc or post-hoc rationalizations of behaviour or in advance of the actus reus. The reflexive violence model proposes that perceptual stimuli has motivational power and this may trigger unwanted actions and hallucinations. The model is based on the theory of ecological perception, where opportunities enabled by an object are cues to act. As an apple triggers a desire to eat, a gun triggers a desire to shoot. These affordances (as they are called are part of the perceptual apparatus, they allow the direct recognition of objects – and in emergencies they enable the fastest possible reactions. Even under normal circumstances, the presence of a weapon will trigger inhibited violent impulses. The presence of a victim will also, but under normal circumstances, these affordances don’t become violent because negative action impulses are totally inhibited, whereas in psychotic illness, negative action impulses are treated as emergencies and bypass frontal inhibitory circuits. What would have been object recognition becomes a blind automatic action. A range of mental illnesses can cause inhibition to be bypassed. At its most innocuous, this causes both simple hallucinations (where the motivational power of an object is misattributed. But ecological perception may have the power to trigger serious violence also –a kind that’s devoid of motives or planning and is often shrouded in amnesia or post-rational delusions

  6. Modeling depth from motion parallax with the motion/pursuit ratio

    Directory of Open Access Journals (Sweden)

    Mark eNawrot

    2014-10-01

    Full Text Available The perception of unambiguous scaled depth from motion parallax relies on both retinal image motion and an extra-retinal pursuit eye movement signal. The motion/pursuit ratio represents a dynamic geometric model linking these two proximal cues to the ratio of depth to viewing distance. An important step in understanding the visual mechanisms serving the perception of depth from motion parallax is to determine the relationship between these stimulus parameters and empirically determined perceived depth magnitude. Observers compared perceived depth magnitude of dynamic motion parallax stimuli to static binocular disparity comparison stimuli at three different viewing distances, in both head-moving and head-stationary conditions. A stereo-viewing system provided ocular separation for stereo stimuli and monocular viewing of parallax stimuli. For each motion parallax stimulus, a point of subjective equality was estimated for the amount of binocular disparity that generates the equivalent magnitude of perceived depth from motion parallax. Similar to previous results, perceived depth from motion parallax had significant foreshortening. Head-moving conditions produced even greater foreshortening due to the differences in the compensatory eye movement signal. An empirical version of motion/pursuit law, termed the empirical motion/pursuit ratio, which models perceived depth magnitude from these stimulus parameters, is proposed.

  7. Modeling depth from motion parallax with the motion/pursuit ratio.

    Science.gov (United States)

    Nawrot, Mark; Ratzlaff, Michael; Leonard, Zachary; Stroyan, Keith

    2014-01-01

    The perception of unambiguous scaled depth from motion parallax relies on both retinal image motion and an extra-retinal pursuit eye movement signal. The motion/pursuit ratio represents a dynamic geometric model linking these two proximal cues to the ratio of depth to viewing distance. An important step in understanding the visual mechanisms serving the perception of depth from motion parallax is to determine the relationship between these stimulus parameters and empirically determined perceived depth magnitude. Observers compared perceived depth magnitude of dynamic motion parallax stimuli to static binocular disparity comparison stimuli at three different viewing distances, in both head-moving and head-stationary conditions. A stereo-viewing system provided ocular separation for stereo stimuli and monocular viewing of parallax stimuli. For each motion parallax stimulus, a point of subjective equality (PSE) was estimated for the amount of binocular disparity that generates the equivalent magnitude of perceived depth from motion parallax. Similar to previous results, perceived depth from motion parallax had significant foreshortening. Head-moving conditions produced even greater foreshortening due to the differences in the compensatory eye movement signal. An empirical version of the motion/pursuit law, termed the empirical motion/pursuit ratio, which models perceived depth magnitude from these stimulus parameters, is proposed.

  8. Modeling Human Control of Self-Motion Direction With Optic Flow and Vestibular Motion.

    Science.gov (United States)

    Zaal, Peter M T; Nieuwenhuizen, Frank M; van Paassen, Marinus M; Mulder, Max

    2013-04-01

    In this paper, we investigate the effects of visual and motion stimuli on the manual control of one's direction of self-motion. In a flight simulator, subjects conducted an active target-following disturbance-rejection task, using a compensatory display. Simulating a vehicular control task, the direction of vehicular motion was shown on the outside visual display in two ways: an explicit presentation using a symbol and an implicit presentation, namely, through the focus of radial outflow that emerges from optic flow. In addition, the effects of the relative strength of congruent vestibular motion cues were investigated. The dynamic properties of human visual and vestibular motion perception paths were modeled using a control-theoretical approach. As expected, improved tracking performance was found for the configurations that explicitly showed the direction of self-motion. The human visual time delay increased with approximately 150 ms for the optic flow conditions, relative to explicit presentations. Vestibular motion, providing higher order information on the direction of self-motion, allowed subjects to partially compensate for this visual perception delay, improving performance. Parameter estimates of the operator control model show that, with vestibular motion, the visual feedback becomes stronger, indicating that operators are more confident to act on optic flow information when congruent vestibular motion cues are present.

  9. The swallowing reflex and its significance as an airway defensive reflex

    Directory of Open Access Journals (Sweden)

    Takashi eNishino

    2013-01-01

    Full Text Available Swallowing function, in humans, is very complex. Swallowing plays, not only an important role in food digestion, but also a major role in preventing the entrance of food and/or other materials into the lower respiratory tract. To achieve this, precise coordination is necessary between breathing and swallowing since the pharynx serves as a common pathway for both respiration and digestion. The swallowing reflex consists of afferent pathways, central integration, and efferent pathways. Any defect or disorder along reflex arc can cause a potential delay or impairment in swallow function. The swallowing reflex can be modulated not only by pathological factors but also by physiological factors. Among these, timing of swallows in relation to the phase of respiration may be the most important factor that determines the occurrence of pulmonary aspiration, since phases of inspiration and the expiration-inspiration transition are the most vulnerable for pulmonary aspiration.

  10. Sound-contingent visual motion aftereffect

    Directory of Open Access Journals (Sweden)

    Kobayashi Maori

    2011-05-01

    Full Text Available Abstract Background After a prolonged exposure to a paired presentation of different types of signals (e.g., color and motion, one of the signals (color becomes a driver for the other signal (motion. This phenomenon, which is known as contingent motion aftereffect, indicates that the brain can establish new neural representations even in the adult's brain. However, contingent motion aftereffect has been reported only in visual or auditory domain. Here, we demonstrate that a visual motion aftereffect can be contingent on a specific sound. Results Dynamic random dots moving in an alternating right or left direction were presented to the participants. Each direction of motion was accompanied by an auditory tone of a unique and specific frequency. After a 3-minutes exposure, the tones began to exert marked influence on the visual motion perception, and the percentage of dots required to trigger motion perception systematically changed depending on the tones. Furthermore, this effect lasted for at least 2 days. Conclusions These results indicate that a new neural representation can be rapidly established between auditory and visual modalities.

  11. An experimental study of artificial murine bladder reflex arc established by abdominal reflex

    Institute of Scientific and Technical Information of China (English)

    WANG Jin-wu; ZHAO Yu-wu; HOU Chun-lin; NI Wei-feng; RUI Bi-yu; GUO Shang-chun; ZHENG Xian-you; DAI Ke-rong

    2011-01-01

    Background The neurogenic bladder dysfunction caused by spinal cord injury is difficult to treat clinically. The aim of this research was to establish an artificial bladder reflex arc in rats through abdominal reflex pathway above the level of spinal cord injury, reinnervate the neurogenic bladder and restore bladder micturition.Methods The outcome was achieved by intradural microanastomosis of the right T13 ventral root to S2 ventral root with autogenous nerve grafting, leaving the right T13 dorsal root intact. Long-term function of the reflex arc was assessed from nerve electrophysiological data and intravesical pressure tests during 8 months postoperation. Horseradish peroxidase (HRP) tracing was performed to observe the effectiveness of the artificial reflex.Results Single stimulus (3 mA, 0.3 ms pulses, 20 Hz, 5-second duration) on the right T13 dorsal root resulted in evoked action potentials, raised intravesical pressures and bladder smooth muscle, compound action potential recorded from the right vesical plexus before and after the spinal cord transaction injury between L5 and S4 segmental in 12 Sprague-Dawley rats. There were HRP labelled cells in T13 ventral horn on the experimental side and in the intermediolateral nucleus on both sides of the L6-S4 segments after HRP injection. There was no HRP labelled cell in T13 ventral horn on the control side.Conclusion Using the surviving somatic reflex above the level of spinal cord injury to reconstruct the bladder autonomous reflex arc by intradural microanastomosis of ventral root with a segment of autologous nerve grafting is practical in rats and may have clinical applications for humans.

  12. Reflex receptive fields for human withdrawal reflexes elicited by non-painful and painful electrical stimulation of the foot sole.

    Science.gov (United States)

    Andersen, O K; Sonnenborg, F A; Arendt-Nielsen, L

    2001-04-01

    Human withdrawal reflex receptive fields (RRFs) were assessed for 4 different electrical stimulus intensities, ranging from below the pain threshold (PTh) to up to two times the PTh intensity (0.8x, 1.2x, 1.6x, and 2.0xPTh). Thirteen subjects participated, and the reflexes were recorded in a sitting position. The stimuli were delivered in random order to 12 positions distributed over the foot sole. Tibialis anterior (TA), gastrocnemius medialis (GM), vastus lateralis (VL), and biceps femoris (BF) reflexes were recorded. Further, knee and ankle joint angle changes were recorded. The strongest reflexes were seen in the TA compared with the other 3 muscles. Dorsi-flexion dominated distal to the talocrural joint corresponding to the TA receptive field area. An expansion of the RRF for the TA and GM was seen when increasing the stimulus intensity from 0.8xPTh to 1.2xPTh and from 1.2xPTh to 1.6xPTh, indicating a gradually increasing reflex threshold towards the border, where TA contraction is inappropriate in a withdrawal reaction. For the BF and VL, the borders of the RRF areas were not detected. By integrating the reflex size within the RRF (i.e. the reflex volume), gradually increasing reflexes for increasing stimulus intensity were seen in all 4 muscles tested, most clearly in the TA and GM. The subjective pain intensity correlated to the reflex volume for the TA, GM, and BF. In conclusion, the highest reflex sensitivity was seen in the centre of the RRF, while the stimulus intensity needed for eliciting a reflex increased towards the receptive field border. Within the RRF, stronger reflexes were evoked for increasing stimulus intensity. The limit in the size of the receptive field size for the TA and GM supports a modular withdrawal reflex organisation.

  13. Vergence-dependent adaptation of the vestibulo-ocular reflex

    Science.gov (United States)

    Lewis, Richard F.; Clendaniel, Richard A.; Zee, David S.; Shelhamer, M. J. (Principal Investigator)

    2003-01-01

    The gain of the vestibulo-ocular reflex (VOR) normally depends on the distance between the subject and the visual target, but it remains uncertain whether vergence angle can be linked to changes in VOR gain through a process of context-dependent adaptation. In this study, we examined this question with an adaptation paradigm that modified the normal relationship between vergence angle and retinal image motion. Subjects were rotated sinusoidally while they viewed an optokinetic (OKN) stimulus through either diverging or converging prisms. In three subjects the diverging prisms were worn while the OKN stimulus moved out of phase with the head, and the converging prisms were worn when the OKN stimulus moved in-phase with the head. The relationship between the vergence angle and OKN stimulus was reversed in the fourth subject. After 2 h of training, the VOR gain at the two vergence angles changed significantly in all of the subjects, evidenced by the two different VOR gains that could be immediately accessed by switching between the diverged and converged conditions. The results demonstrate that subjects can learn to use vergence angle as the contextual cue that retrieves adaptive changes in the angular VOR.

  14. Assessment of Hyperactive Reflexes in Patients with Spinal Cord Injury

    Science.gov (United States)

    Yang, Chung-Yong

    2015-01-01

    Hyperactive reflexes are commonly observed in patients with spinal cord injury (SCI) but there is a lack of convenient and quantitative characterizations. Patellar tendon reflexes were examined in nine SCI patients and ten healthy control subjects by tapping the tendon using a hand-held instrumented hammer at various knee flexion angles, and the tapping force, quadriceps EMG, and knee extension torque were measured to characterize patellar tendon reflexes quantitatively in terms of the tendon reflex gain (G tr), contraction rate (R c), and reflex loop time delay (t d). It was found that there are significant increases in G tr and R c and decrease in t d in patients with spinal cord injury as compared to the controls (P reflex excitability and muscle contraction dynamics. With proper simplifications, it can potentially be used for quantitative diagnosis and outcome evaluations of hyperreflexia in clinical settings. PMID:25654084

  15. The parallel programming of voluntary and reflexive saccades.

    Science.gov (United States)

    Walker, Robin; McSorley, Eugene

    2006-06-01

    A novel two-step paradigm was used to investigate the parallel programming of consecutive, stimulus-elicited ('reflexive') and endogenous ('voluntary') saccades. The mean latency of voluntary saccades, made following the first reflexive saccades in two-step conditions, was significantly reduced compared to that of voluntary saccades made in the single-step control trials. The latency of the first reflexive saccades was modulated by the requirement to make a second saccade: first saccade latency increased when a second voluntary saccade was required in the opposite direction to the first saccade, and decreased when a second saccade was required in the same direction as the first reflexive saccade. A second experiment confirmed the basic effect and also showed that a second reflexive saccade may be programmed in parallel with a first voluntary saccade. The results support the view that voluntary and reflexive saccades can be programmed in parallel on a common motor map.

  16. Sympathetic reflex control of blood flow in human peripheral tissues

    DEFF Research Database (Denmark)

    Henriksen, O

    1991-01-01

    Sympathetic vasoconstrictor reflexes are essential for the maintenance of arterial blood pressure in upright position. It has been generally believed that supraspinal sympathetic vasoconstrictor reflexes elicited by changes in baroreceptor activity play an important role. Recent studies on human ...... to collision of normodromically and antidromically conducted impulses in efferent sympathetic vasoconstrictor fibers. The evidence obtained suggests that sympathetic vasoconstrictor reflexes to postural changes are complex and highly differentiated....

  17. A syntactic and lexical approach to French reflexive verbs

    Directory of Open Access Journals (Sweden)

    Corina Petersilka

    2012-01-01

    Full Text Available This Construction grammar approach to French refl exive verbs describes the formal and semantic constraints at work in the different refl exive constructions, points out at their different branches of inheritance and shows cases of fusion with other argument structures. The article suggests a family tree of French reflexive constructions which appear to be derived from different transitive constructions. It also deals with how the reflexive argument structure modifies the semantics of the transitive verb used in reflexive construction.

  18. Sympathetic reflex control of blood flow in human peripheral tissues

    DEFF Research Database (Denmark)

    Henriksen, O

    1991-01-01

    Sympathetic vasoconstrictor reflexes are essential for the maintenance of arterial blood pressure in upright position. It has been generally believed that supraspinal sympathetic vasoconstrictor reflexes elicited by changes in baroreceptor activity play an important role. Recent studies on human...... sympathetic vasoconstrictor reflexes are blocked. Blood flow has been measure by the local 133Xe-technique. The results indicate the presence of spinal as well as supraspinal sympathetic vasoconstrictor reflexes to human peripheral tissues. Especially is emphasized the presence of a local sympathetic veno...

  19. Binocular Coordination of the Human Vestibulo-Ocular Reflex during Off-axis Pitch Rotation

    Science.gov (United States)

    Wood, S. J.; Reschke, M. F.; Kaufman, G. D.; Black, F. O.; Paloski, W. H.

    2006-01-01

    Head movements in the sagittal pitch plane typically involve off-axis rotation requiring both vertical and horizontal vergence ocular reflexes to compensate for angular and translational motion relative to visual targets of interest. The purpose of this study was to compare passive pitch VOR responses during rotation about an Earth-vertical axis (canal only cues) with off-axis rotation (canal and otolith cues). Methods. Eleven human subjects were oscillated sinusoidally at 0.13, 0.3 and 0.56 Hz while lying left-side down with the interaural axis either aligned with the axis of rotation or offset by 50 cm. In a second set of measurements, twelve subjects were also tested during sinusoidally varying centrifugation over the same frequency range. The modulation of vertical and horizontal vergence ocular responses was measured with a binocular videography system. Results. Off-axis pitch rotation enhanced the vertical VOR at lower frequencies and enhanced the vergence VOR at higher frequencies. During sinusoidally varying centrifugation, the opposite trend was observed for vergence, with both vertical and vergence vestibulo-ocular reflexes being suppressed at the highest frequency. Discussion. These differential effects of off-axis rotation over the 0.13 to 0.56 Hz range are consistent with the hypothesis that otolith-ocular reflexes are segregated in part on the basis of stimulus frequency. At the lower frequencies, tilt otolith-ocular responses compensate for declining canal input. At higher frequencies, translational otolith-ocular reflexes compensate for declining visual contributions to the kinematic demands required for fixating near targets.

  20. The legacy of care as reflexive learning.

    Science.gov (United States)

    García, Marta Rodríguez; Moya, Jose Luis Medina

    2016-06-14

    to analyze whether the tutor's use of reflexive strategies encourages the students to reflect. The goal is to discover what type of strategies can help to achieve this and how tutors and students behave in the practical context. a qualitative and ethnographic focus was adopted. Twenty-seven students and 15 tutors from three health centers participated. The latter had received specific training on reflexive clinical tutoring. The analysis was developed through constant comparisons of the categories. the results demonstrate that the tutors' use of reflexive strategies such as didactic questioning, didactic empathy and pedagogical silence contributes to encourage the students' reflection and significant learning. reflexive practice is key to tutors' training and students' learning. analisar se o uso de estratégias reflexivas por parte da tutora de estágio clínico estimula a reflexão nos estudantes. A intenção é descobrir qual tipo de estratégias podem ajudar a fazê-lo e como as tutoras e os estudantes se comportam no contexto prático. foi adotado um enfoque qualitativo de cunho etnográfico em que participaram 27 estudantes e 15 tutores de três centros de saúde que haviam recebido formação específica sobre tutoria clínica reflexiva. A análise foi realizada por meio de comparações constantes das categorias. os resultados demonstram que o uso de estratégias reflexivas como a interrogação didática, a empatia didática e o silêncio pedagógico por parte das tutoras, contribui para fomentar a reflexão do estudante e sua aprendizagem significativa. a prática reflexiva é a chave para a formação dos tutores e para a aprendizagem dos estudantes. analizar si el uso de estrategias reflexivas por parte de la tutora de prácticas clínicas fomenta la reflexión en los estudiantes. Se trata de conocer qué tipo de estrategias pueden ayudar a hacerlo y cómo se comportan tutoras y estudiantes en el contexto práctico. se ha utilizado un enfoque

  1. ARISK PHENOMENA IN THE SILVANIA MOUNTAINS, INTUITIVE AND GENETIC REFLEXES

    Directory of Open Access Journals (Sweden)

    CAMELIA BOGDAN

    2014-05-01

    Full Text Available Risk phenomena in the Silvania Mountains, intuitive and genetic reflexes. In the contemporary period, the scientific research under the auspices of the global development has experienced a real quantitative and qualitative revolution. Theoretically and methodologically, the widespread promotion of the “concept of discontinuity” in terms of content, significances, manifestation, implications is observed, which has become a new imperative of the nowadays geography. The phenomena of discontinuity happen as real “paroxysmal, rhythm and intensity ruptures“ in relation to the normal occurrence defined either through the average value, determined on statistical basis as hydrological, meteorological, climatic phenomena or in discrete forms, when the phenomena occur in a veiled manner and they are perceptible only through their effects, respectively the environmental reflexes. Among the notions used with reference to extreme evolutionary discontinuities, we quote: the hazard, the disaster, the calamity and the risk to which was added a series of related notions: stability, sensitivity, resilience, fragility and vulnerability. The Silvania Mountains, a representative territorial unit within Silvania Land, with a fascinating and controversial geological origin, a real petrographic synthesis with uncovered crystalline stone, brought to the surface due to erosion under the layers of Neogene sediments, as a last remaining of a grandiose Hercynian chain with a varied orientation SW-NE of which were part the Massif Central –France, the east side, the Vosges Mountains, the Black Forest Mountains, the Harz Mountains and Bohemia. In this range of mountains, we also mention the Silvania Hercynian Mountains, respectively Plopiș and Meseș Mountains.This mountainous elevation level has an important role within the landscape as "geographical discontinuity factor” on one hand, between the Someșan Plateau and the Silvania piedmontan hills (Meseș Mountains

  2. Motion Simulator

    Science.gov (United States)

    1993-01-01

    MOOG, Inc. supplies hydraulic actuators for the Space Shuttle. When MOOG learned NASA was interested in electric actuators for possible future use, the company designed them with assistance from Marshall Space Flight Center. They also decided to pursue the system's commercial potential. This led to partnership with InterActive Simulation, Inc. for production of cabin flight simulators for museums, expositions, etc. The resulting products, the Magic Motion Simulator 30 Series, are the first electric powered simulators. Movements are computer-guided, including free fall to heighten the sense of moving through space. A projection system provides visual effects, and the 11 speakers of a digital laser based sound system add to the realism. The electric actuators are easier to install, have lower operating costs, noise, heat and staff requirements. The U.S. Space & Rocket Center and several other organizations have purchased the simulators.

  3. Lower esophageal sphincter relaxation reflex kinetics: effects of peristaltic reflexes and maturation in human premature neonates.

    Science.gov (United States)

    Pena, Eneysis M; Parks, Vanessa N; Peng, Juan; Fernandez, Soledad A; Di Lorenzo, Carlo; Shaker, Reza; Jadcherla, Sudarshan R

    2010-12-01

    We defined the sensory-motor characteristics of the lower esophageal sphincter relaxation (LESR) (stimulus threshold volume, response onset, and relaxation period, relaxation magnitude, nadir) during maturation in human neonates. We hypothesized that LESR kinetics differs during maturation and with peristaltic reflex type. Basal and adaptive esophageal motility testing was performed (N = 20 premature neonates) at 34.7 and 39.1 wk (time 1 and time 2). Effects of midesophageal provocation with graded stimuli (N = 1,267 stimuli, air and liquids) on LESR kinetics during esophagodeglutition response (EDR) and secondary peristalsis (SP) were analyzed by mixed models. Frequency of LESR with basal primary peristalsis were different during maturation (P = 0.03). During adaptive responses with maturation, 1) the frequencies of peristaltic reflexes and LESR were similar; 2) liquid stimuli resulted in a shorter LESR response latency and LESR nadir and greater LESR magnitude (all P reflexes at both times (vs. none, P reflex, and postnatal maturation. Maturation modulates an increased recruitment of inhibitory pathways that favor LESR.

  4. An Enabling Framework for Reflexive Learning: Experiential Learning and Reflexivity in Contemporary Modernity

    Science.gov (United States)

    Dyke, Martin

    2009-01-01

    The paper presents an enabling framework for experiential learning that connects with reflexive modernity. This framework places an emphasis on learning with others and on the role of theory, practice and reflection. A sociological argument is constructed for an alternative framework for experiential learning that derives from social theory. It is…

  5. Methodological Reflexivity: Towards Evolving Methodological Frameworks through Critical and Reflexive Deliberations

    Science.gov (United States)

    Raven, Glenda

    2006-01-01

    In this article, the author argues for a central and critical role for "reflexivity in research" with the aim of developing and strengthening not only everyone's understanding of what everyone does in environmental education research, but also how, and why everyone does it. In a narrative account of methodological issues that occurred…

  6. Reflexivity and vulnerability in collaborative knowledge production

    DEFF Research Database (Denmark)

    Jakobsen, Helle Nordentoft; Olesen, Birgitte Ravn

    in the interaction between the peers. This can, for instance be observed in the participants’ tone of voice and body-language. In other words, these moments can be seen as naturally occurring ‘breaching incidents’ in an apparently fruitful learning environment (Have, 2004). As such, they have potential to expose...... the normativity,, of the ways in which roles and relationships between the peers and researchers unfold. In both instances, the ambition was to create a reflexive learning environment in which peers co-produce new knowledge on how to communicate with patients and relatives; however, we conclude that the opposite...

  7. Motion Picture and Videotape Analysis of Behavior.

    Science.gov (United States)

    Carpenter, Geoffrey C.; Duvall, David

    1983-01-01

    Use of motion pictures and videotape recordings to analyze animal behavior is described. Indicates that accuracy/amount of data available is greatly increased and that simultaneous behaviors of different animals can be studied or individual behavior patterns increased/decreased, providing observers with temporal perceptions similar to the animals…

  8. Reflexivity and adjustment strategies at the interfaces

    Directory of Open Access Journals (Sweden)

    Ismael Teomiro

    2011-10-01

    Full Text Available I argue in this work that Reinhart & Reuland’s (1993 conditions A and B hold for Spanish. I provide evidence supporting the hypothesis that this language makes use of both SE and SELF-anaphors. Inherent reflexive verbs undergo an internal argument reduction operation in the lexicon. However, the syntax always requires two arguments. Therefore certain clitics, which are SE-anaphors, are inserted in these derivations. This is a last-resort mechanism that makes an adjustment between the valence of the lexical entry of the verb and the requirements of the syntax in order for the derivation to converge at the C-I interface. These clitics are syntactic arguments. Nevertheless, they are not interpreted as semantic arguments since they violate the double chain condition, which forces nominal elements to share both a tense and thematic features with the verb and the tense heads. Non- inherent reflexive verbs require the presence of a SELF-anaphor, which is formed out of a SE-anaphor along with a protector SELF element. Therefore, both syntactic elements are interpreted as two distinguishable semantic elements at C-I despite the fact that there is binding between them both. The interpretation of both syntactic elements as just one semantic element is a pragmatic epiphenomenon.

  9. The Self-Reflexivity of Social Action

    Directory of Open Access Journals (Sweden)

    Bogdan POPOVENIUC

    2015-12-01

    Full Text Available The most puzzling and striking feature of Social Theory lies in the impossibility to control its leaning toward self-fulfilling statements. In Sociology, the epistemic explanation become part of explained world and the Theory is at risk to become either futile or subjective along with the dialectic evolution of social understanding. As major mature sciences, it has solid instruments and methods for acquiring useful knowledge, self-regulatory rules for assuring the accuracy of its affirmations and errors refutation. More than any other sciences, it achieved the level of meta-theoretical thinking about its own practice and sets up its limits and expertise. However this is not enough. The understanding brought by sociological the most evolved concept of reflexivity is overwhelmed complexity of social reality, because it fails to cover the self-reference supposed by itself. The Scientific discourse of third person should be transcended toward the level of dialectical co-constructed consciousness-reality awareness, that the subjective “I”, is the condition of possibility for objective knowledge (of Science, which, in turn, represents the categorical conditions of possibility for (self-understanding. A self-reflexive level of understanding instead, would illuminate many concealed suppositions, conundrums and inconsistencies of social discourse and reasoning. This enhancement is also required to put the present uncontrolled collective intelligent development of Mankind on a safety and desirable path.

  10. Effect of guaifenesin on cough reflex sensitivity.

    Science.gov (United States)

    Dicpinigaitis, Peter V; Gayle, Yvonne E

    2003-12-01

    Guaifenesin, a commonly used agent for the treatment of cough, is termed an expectorant since it is believed to alleviate cough discomfort by increasing sputum volume and decreasing its viscosity, thereby promoting effective cough. Despite its common usage, relatively few studies, yielding contrasting results, have been performed to investigate the action and efficacy of guaifenesin. To evaluate the effect of guaifenesin on cough reflex sensitivity. Randomized, double-blind, placebo-controlled trial. Academic medical center. Fourteen subjects with acute viral upper respiratory tract infection (URI) and 14 healthy volunteers. On 2 separate days, subjects underwent capsaicin cough challenge 1 to 2 h after receiving a single, 400-mg dose (capsules) of guaifenesin or matched placebo. The concentration of capsaicin inducing five or more coughs (C(5)) was determined. Among subjects with URI, mean (+/- SEM) log C(5) after guaifenesin and placebo were 0.92 +/- 0.17 and 0.66 +/- 0.14, respectively (p = 0.028). No effect on cough sensitivity was observed in healthy volunteers. Our results demonstrate that guaifenesin inhibits cough reflex sensitivity in subjects with URI, whose cough receptors are transiently hypersensitive, but not in healthy volunteers. Possible mechanisms include a central antitussive effect, or a peripheral effect by increased sputum volume serving as a barrier shielding cough receptors within the respiratory epithelium from the tussive stimulus.

  11. Cough reflex sensitization from esophagus and nose.

    Science.gov (United States)

    Hennel, Michal; Brozmanova, Mariana; Kollarik, Marian

    2015-12-01

    The diseases of the esophagus and nose are among the major factors contributing to chronic cough although their role in different patient populations is debated. Studies in animal models and in humans show that afferent C-fiber activators applied on esophageal or nasal mucosa do not initiate cough, but enhance cough induced by inhaled irritants. These results are consistent with the hypothesis that activation of esophageal and nasal C-fibers contribute to cough reflex hypersensitivity observed in chronic cough patients with gastroesophageal reflux disease (GERD) and chronic rhinitis, respectively. The afferent nerves mediating cough sensitization from the esophagus are probably the neural crest-derived vagal jugular C-fibers. In addition to their responsiveness to high concentration of acid typical for gastroesophageal reflux (pH cough sensitization are less understood. Increased cough reflex sensitivity was also reported in many patients with GERD or rhinitis who do not complain of cough indicating that additional endogenous or exogenous factors may be required to develop chronic coughing in these diseases.

  12. Somatoautonomic reflexes in acupuncture therapy: A review.

    Science.gov (United States)

    Uchida, Sae; Kagitani, Fusako; Sato-Suzuki, Ikuko

    2017-03-01

    Oriental therapies such as acupuncture, moxibustion, or Anma, have been used to treat visceral disorders since ancient times. In each of these therapies, stimulation of the skin or underlying muscles leads to excitation of afferent nerves. The sensory information is carried to the central nervous system, where it is transferred to autonomic efferents, thus affecting visceral functions. This neuronal pathway, known as the "somatoautonomic reflex", has been systematically studied by Sato and his colleagues for over a half century. Nearly all their studies were conducted in anesthetized animals, whereas human patients are conscious. Responses in patients or the events following therapeutic somatic stimulation may differ from those observed in anesthetized animals. In fact, it is increasingly apparent that the responses in patients and animals are not always coincident, and the differences have been difficult for clinicians to reconcile. We review the mechanism of the "somatoautonomic reflex" as described in anesthetized animals and then discuss how it can be applied clinically. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Metabolic syndrome and the hepatorenal reflex

    Directory of Open Access Journals (Sweden)

    Michael D Wider

    2016-01-01

    Full Text Available Insufficient hepatic O 2 in animal and human studies has been shown to elicit a hepatorenal reflex in response to increased hepatic adenosine, resulting in stimulation of renal as well as muscle sympathetic nerve activity and activating the renin angiotensin system. Low hepatic ATP, hyperuricemia, and hepatic lipid accumulation reported in metabolic syndrome (MetS patients may reflect insufficient hepatic O 2 delivery, potentially accounting for the sympathetic overdrive associated with MetS. This theoretical concept is supported by experimental results in animals fed a high fructose diet to induce MetS. Hepatic fructose metabolism rapidly consumes ATP resulting in increased adenosine production and hyperuricemia as well as elevated renin release and sympathetic activity. This review makes the case for the hepatorenal reflex causing sympathetic overdrive and metabolic syndrome in response to exaggerated splanchnic oxygen consumption from excessive eating. This is strongly reinforced by the fact that MetS is cured in a matter of days in a significant percentage of patients by diet, bariatric surgery, or endoluminal sleeve, all of which would decrease splanchnic oxygen demand by limiting nutrient contact with the mucosa and reducing the nutrient load due to the loss of appetite or dietary restriction.

  14. The Role of Transformational Leadership in Enhancing Team Reflexivity

    NARCIS (Netherlands)

    M.C. Schippers (Michaéla); D.N. den Hartog (Deanne); P.L. Koopman (Paul); D.L. van Knippenberg (Daan)

    2007-01-01

    textabstractTeam reflexivity, or the extent to which teams reflect upon and modify their functioning, has been identified as a key factor in the effectiveness of work teams. As yet, however, little is known about the factors that play a role in enhancing team reflexivity, and it is thus important to

  15. Bourdieu and Science Studies: Toward a Reflexive Sociology

    Science.gov (United States)

    Hess, David J.

    2011-01-01

    Two of Bourdieu's fundamental contributions to science studies--the reflexive analysis of the social and human sciences and the concept of an intellectual field--are used to frame a reflexive study of the history and social studies of science and technology as an intellectual field in the United States. The universe of large, Ph.D.-granting…

  16. The role of transformational leadership in enhancing team reflexivity

    NARCIS (Netherlands)

    Schippers, M.C.; den Hartog, D.N.; Koopman, P.L.; van Knippenberg, D.

    2008-01-01

    Team reflexivity, or the extent to which teams reflect upon and modify their functioning, has been identified as a key factor in the effectiveness of work teams. As yet, however, little is known about the factors that play a role in enhancing team reflexivity, and it is thus important to develop the

  17. [Value of blink reflex studies in neurosurgical problems].

    Science.gov (United States)

    Jamjoom, Z; Nahser, H C; Nau, H E

    1983-09-01

    Blinking reflex studies were done in neurosurgical patients with processes in the posterior fossa and idiopathic trigeminal neuralgia. Alterations were found in space occupying, ischemic, and traumatic lesions of the trigemino-facial system. The analysis of the components of the blinking reflex can give hints to the site of the lesion and also to the prognosis of the underlying process.

  18. (Re)constructing Reflexivity: A Relational Constructionist Approach

    NARCIS (Netherlands)

    Hosking, D.M.; Pluut, B.

    2010-01-01

    This article distinguishes three discourses of reflexivity in relation to human inquiry. One of these arises from a post-modern, relational constructionist perspective which radically re-conceptualizes reflexivity: (a) as a local and co-constructed process oriented towards the question (b) how are w

  19. Reflexivity in Teams: A Review and New Perspectives.

    Science.gov (United States)

    Konradt, Udo; Otte, Kai-Philip; Schippers, Michaéla C; Steenfatt, Corinna

    2016-01-01

    Team reflexivity posits that the extent to which teams reflect upon and adapt their functioning is positively related to team performance. While remarkable progress has been made to provide evidence of this relationship, the underlying framework is missing elements of current theoretical streams for analyzing and describing teamwork, leaving the diversity of effects of team reflexivity often untouched. In this article, we present an update for this framework, by reviewing previous research on reflexivity, addressing gaps in the literature, and revising the original model by integrating feedback and dynamic team effectiveness frameworks for describing temporal developments of reflexivity. We furthermore propose a new dimensional structure for reflexivity, relying on prior work conceptualizing teams as information-processing systems that learn and advance through social-cognitive elements. Our model is therefore not only suitable for explaining the diverse set of relationships between team reflexivity on outcomes, but also provides valuable directions for viewing reflexivity as process that takes place during both transition and action phases of teamwork. We conclude with implications for managers, identify limitations, and propose an agenda for further research into this area. This article contributes an extended perspective relevant for further theory development and for effectively managing reflexivity in teams.

  20. Iris Pigmentation and Fractionated Reaction and Reflex Time.

    Science.gov (United States)

    Hale, Bruce D.; And Others

    Behavioral measures, fractionated reaction and reflex times by means of electromyography, were used to determine if the eye color differences are found in the central or peripheral regions of the nervous system. The purpose of this research was to determine the truth of the hypothesis that dark-eyed individuals have faster reflex and reaction time…

  1. [The development of I. P. Pavlov's conditioned reflex theory].

    Science.gov (United States)

    Kim, O J

    1992-01-01

    This paper deals with the theory of Ivan Petrovich Pavlov (1849-1936), a Russian physiologist who presented for the first time the systematic theory of the function of the brain that controls the whole behavior of animals, i.e. higher nervous activity through experimental studies. This paper, principally based on Lectures on Conditioned Reflexes (1928), investigates the development of conditioned reflex theory from its beginning by dividing it into three periods. First, during the period from 1898 to 1906, the fundamental concept of conditioned reflex was established and the study of conditioned reflex became an independent discipline. From 1907 to 1916, the second period, Pavlov theorized on higher nervous activity on the basis of extensive data from his laboratory experiments of conditioned reflex. And Pavlov complemented conditioned reflex theory, during the third period from 1916 to 1928, and extended the boundaries of it through applications of conditioned reflex theory to psychopathology and typology. The study contributes to the understanding that conditioned reflex theory was historically developed, and not presented as a complete form from the beginning, and that Pavlov intended to study the higher nervous activity through the method of neurophysiology.

  2. (Re)constructing Reflexivity: A Relational Constructionist Approach

    NARCIS (Netherlands)

    Hosking, D.M.; Pluut, B.

    2010-01-01

    This article distinguishes three discourses of reflexivity in relation to human inquiry. One of these arises from a post-modern, relational constructionist perspective which radically re-conceptualizes reflexivity: (a) as a local and co-constructed process oriented towards the question (b) how are

  3. Ultimate concerns in late modernity: Archer, Bourdieu and reflexivity.

    Science.gov (United States)

    Farrugia, David; Woodman, Dan

    2015-12-01

    Through a critique of Margaret Archer's theory of reflexivity, this paper explores the theoretical contribution of a Bourdieusian sociology of the subject for understanding social change. Archer's theory of reflexivity holds that conscious 'internal conversations' are the motor of society, central both to human subjectivity and to the 'reflexive imperative' of late modernity. This is established through critiques of Bourdieu, who is held to erase creativity and meaningful personal investments from subjectivity, and late modernity is depicted as a time when a 'situational logic of opportunity' renders embodied dispositions and the reproduction of symbolic advantages obsolete. Maintaining Archer's focus on 'ultimate concerns' in a context of social change, this paper argues that her theory of reflexivity is established through a narrow misreading and rejection of Bourdieu's work, which ultimately creates problems for her own approach. Archer's rejection of any pre-reflexive dimensions to subjectivity and social action leaves her unable to sociologically explain the genesis of 'ultimate concerns', and creates an empirically dubious narrative of the consequences of social change. Through a focus on Archer's concept of 'fractured reflexivity', the paper explores the theoretical necessity of habitus and illusio for understanding the social changes that Archer is grappling with. In late modernity, reflexivity is valorized just as the conditions for its successful operation are increasingly foreclosed, creating 'fractured reflexivity' emblematic of the complex contemporary interaction between habitus, illusio, and accelerating social change. © London School of Economics and Political Science 2015.

  4. The role of transformational leadership in enhancing team reflexivity

    NARCIS (Netherlands)

    Schippers, M.C.; den Hartog, D.N.; Koopman, P.L.; van Knippenberg, D.

    2008-01-01

    Team reflexivity, or the extent to which teams reflect upon and modify their functioning, has been identified as a key factor in the effectiveness of work teams. As yet, however, little is known about the factors that play a role in enhancing team reflexivity, and it is thus important to develop

  5. Reflex sympathetic dystrophy: Early treatment and psychological aspects

    NARCIS (Netherlands)

    Geertzen, J.H.B.; De Bruijn, H.; De Bruijn-Kofman, A.T.; Arendzen, J.H.

    1994-01-01

    We report the results of two prospective studies of early treatment and psychological aspects in a series of 26 patients with sympathetic reflex dystrophy of the hand in which treatment was started within 3 months after diagnosis. Ismelin blocks is an often used therapy in sympathetic reflex dystrop

  6. The feasibility of reflexive control in transfemoral prostheses

    NARCIS (Netherlands)

    Wentink, E.C.; Rietman, J.S.; Veltink, P.H.

    2009-01-01

    The feasibility of reflexive control in transfemoral prosthesis is assessed using a model of the lower extremity. The artificial triggering of reflexes, the processing of the central nervous system, the EMG detection and the control input to the prosthetic knee all take time. A model was used to ass

  7. Multisensory Contributions to Visual Motion Parsing

    Directory of Open Access Journals (Sweden)

    Salvador Soto-Faraco

    2011-10-01

    Full Text Available In humans, as well as most animal species, perception of object motion is critical to successful interaction with the surrounding environment. Yet, as the observer moves, the retinal projections of the various motion components add to each other and extracting accurate object motion becomes computationally challenging. Recent psychophysical studies have demonstrated that observers use a flow parsing mechanism to estimate and subtract self-motion from the optic flow field. We investigated whether concurrent acoustic cues for motion can facilitate visual flow parsing, thereby enhancing the detection of moving objects during simulated self-motion. Participants identified an object (the target that moved either forward or backward within a visual scene containing nine identical textured objects simulating forward observer translation. We found that spatially co-localized, directionally congruent, moving auditory stimuli enhanced object motion detection. Interestingly, subjects who performed poorly on the visual-only task benefited more from the addition of moving auditory stimuli. When auditory stimuli were not co-localized to the visual target, improvements in detection rates were weak. Taken together, these results suggest that the parsing object motion from self-motion induced optic flow can operate on multisensory object representations.

  8. Collective motion

    Science.gov (United States)

    Vicsek, Tamás; Zafeiris, Anna

    2012-08-01

    We review the observations and the basic laws describing the essential aspects of collective motion - being one of the most common and spectacular manifestation of coordinated behavior. Our aim is to provide a balanced discussion of the various facets of this highly multidisciplinary field, including experiments, mathematical methods and models for simulations, so that readers with a variety of background could get both the basics and a broader, more detailed picture of the field. The observations we report on include systems consisting of units ranging from macromolecules through metallic rods and robots to groups of animals and people. Some emphasis is put on models that are simple and realistic enough to reproduce the numerous related observations and are useful for developing concepts for a better understanding of the complexity of systems consisting of many simultaneously moving entities. As such, these models allow the establishing of a few fundamental principles of flocking. In particular, it is demonstrated, that in spite of considerable differences, a number of deep analogies exist between equilibrium statistical physics systems and those made of self-propelled (in most cases living) units. In both cases only a few well defined macroscopic/collective states occur and the transitions between these states follow a similar scenario, involving discontinuity and algebraic divergences.

  9. Separation Of Form Perception And Stereopsis

    Science.gov (United States)

    Piantanida, Thomas P.; Hammon, Robert W.

    1987-06-01

    This study addresses the question of whether static and dynamic stereopsis require the perception of form. The retinal image requirements of the visual mechanisms subserving form perception and stereopsis are not only distinct but potentially antagonistic. Form perception requires the retinal image to have luminance gradients that are steep enough to produce suprathreshold temporal transients in the receptors during normal eye movements. Stereopsis, on the other hand, requires identification of corresponding luminance gradients in the two retinal images so that their retinal disparity can be calculated. Thus, while the motion of the retinal image caused by normal eye movements is essential to form perception, it may be detrimental to stereopsis. We eliminated the motion of the retinal image that would normally have occurred during eye movements by using a pair of SRI dual-Purkinje-image eyetrackers and stimulus deflectors to stabilize the retinal images of selected form elements. We examined the thresholds for perceiving motion in depth under stabilized and unstabilized conditions and found that the perception of motion in depth continues in the absence of monocular form perception. Likewise, when we stabilized the disparate images of a line stereogram, stereopsis persisted in the absence of form perception of those elements whose retinal disparity deter-mined their perceived depth. These results imply profound separation of the form-perception and stereopsis mechanisms.

  10. Development of Motion Processing in Children with Autism

    Science.gov (United States)

    Annaz, Dagmara; Remington, Anna; Milne, Elizabeth; Coleman, Mike; Campbell, Ruth; Thomas, Michael S. C.; Swettenham, John

    2010-01-01

    Recent findings suggest that children with autism may be impaired in the perception of biological motion from moving point-light displays. Some children with autism also have abnormally high motion coherence thresholds. In the current study we tested a group of children with autism and a group of typically developing children aged 5 to 12 years of…

  11. The Motion Picture and the Teaching of English.

    Science.gov (United States)

    Sheridan, Marion C.; And Others

    Written to help a viewer watch a motion picture perceptively, this book explains the characteristics of the film as an art form and examines the role of motion pictures in the English curriculum. Specific topics covered include (1) the technical aspects of the production of films (the order of "shots," camera angle, and point of view), (2) the…

  12. The Motion Picture and the Teaching of English.

    Science.gov (United States)

    Sheridan, Marion C.; And Others

    Written to help a viewer watch a motion picture perceptively, this book explains the characteristics of the film as an art form and examines the role of motion pictures in the English curriculum. Specific topics covered include (1) the technical aspects of the production of films (the order of "shots," camera angle, and point of view), (2) the…

  13. Human intersegmental reflexes from intercostal afferents to scalene muscles.

    Science.gov (United States)

    McBain, Rachel A; Taylor, Janet L; Gorman, Robert B; Gandevia, Simon C; Butler, Jane E

    2016-10-01

    What is the central question of this study? The aim was to determine whether specific reflex connections operate between intercostal afferents and the scalene muscles in humans, and whether these connections operate after a clinically complete cervical spinal cord injury. What is the main finding and its importance? This is the first description of a short-latency inhibitory reflex connection between intercostal afferents from intercostal spaces to the scalene muscles in able-bodied participants. We suggest that this reflex is mediated by large-diameter afferents. This intercostal-to-scalene inhibitory reflex is absent after cervical spinal cord injury and may provide a way to monitor the progress of the injury. Short-latency intersegmental reflexes have been described for various respiratory muscles in animals. In humans, however, only short-latency reflex responses to phrenic nerve stimulation have been described. Here, we examined the reflex connections between intercostal afferents and scalene muscles in humans. Surface EMG recordings were made from scalene muscles bilaterally, in seven able-bodied participants and seven participants with motor- and sensory-complete cervical spinal cord injury (median 32 years postinjury, range 5 months to 44 years). We recorded the reflex responses produced by stimulation of the eighth or tenth left intercostal nerve. A short-latency (∼38 ms) inhibitory reflex was evident in able-bodied participants, in ipsilateral and contralateral scalene muscles. This bilateral intersegmental inhibitory reflex occurred in 46% of recordings at low stimulus intensities (at three times motor threshold). It was more frequent (in 75-85% of recordings) at higher stimulus intensities (six and nine times motor threshold), but onset latency (38 ± 9 ms, mean ± SD) and the size of inhibition (23 ± 10%) did not change with stimulus intensity. The reflex was absent in all participants with spinal cord injury. As the intercostal

  14. Soleus H-reflex excitability during pedaling post-stroke

    DEFF Research Database (Denmark)

    Schindler-Ivens, Sheila; Brown, David A.; Lewis, Gwyn N.

    2008-01-01

    A major contributor to impaired locomotion post-stroke is abnormal phasing of paretic muscle activity, but the mechanisms remain unclear. Previous studies have shown that, in the paretic limb of people post-stroke, Group Ia reflexes are abnormally elevated and fail to decrease in amplitude during...... the pedaling cycle. H-reflexes were large during extension and small during flexion. Reduced H-reflex modulation post-stroke was associated with the level of neuromuscular impairment as indicated by Fugl-Meyer score. However, regardless of impairment level, stroke subjects displayed H-reflex suppression during...... the flexion phase of pedaling. After correcting for the level of background muscle activity, H-reflexes were found to be larger in paretic as compared to NI individuals, regardless of the phase of the pedaling cycle. We conclude that Group Ia afferent transmission is enhanced in the paretic SO of people post-stroke...

  15. Voluntary Control of the Near Reflex: A Case Report

    Directory of Open Access Journals (Sweden)

    Serpil Akar

    2014-03-01

    Full Text Available Spasm of the near reflex is a rare disorder that involves intermittent and variable episodes of esotropia, pseudomyopia, and pupillary myosis. It is usually functional in origin and is seen mainly in young patients. Treatment options for spasm of the near reflex have had variable success. In instances where the etiology of spasm of the near reflex was suspected to be hysteria, psychotherapy has proven beneficial. We report the case of an 11-year-old girl who had functional spasm of the near reflex. The symptoms persisted for two years. Symptomatic relief was achieved by cycloplegia and spectacle correction (added plus lenses at near. The patient also underwent psychological counseling. In our case, the functional spasm of the near reflex spontaneously resolved after 2 years. (Turk J Ophthalmol 2014; 44: 161-3

  16. Effects of footwear comfort perception on the neuromuscular control of balance.

    Science.gov (United States)

    Burke, Jeanmarie R

    2012-04-01

    The purpose of this research was to determine the effects of footwear comfort perception on the gain of the gastrocnemius H-reflex response during single leg balance tasks. Subjects performed single leg balance tasks while wearing aerobic sneakers with two different pairs of shoe insoles that were subjectively rated for comfort using a reliable 150 mm visual analog scale. The primary outcome was the consistency of decreasing the gain of the gastrocnemius H-reflex with increasing balance task complexity as a function of footwear comfort perception. Among the asymptomatic subjects (n = 11), H-reflex gain significantly decreased by 19% and 10% from balancing on a stable surface to an unstable surface for the shoe-brand and replacement insoles, respectively (p < .05). Among the subjects with musculoskeletal disorders (n = 13), H-reflex gain significantly decreased by 10% from balancing on a stable surface to an unstable surface when wearing custom-molded foot orthotics, but H-reflex gain significantly increased by 27% from balancing on a stable surface to an unstable surface when wearing replacement insoles (p < .05). Decreases in footwear comfort perception may negatively impact the attenuation of gastrocnemius H-reflex gain that contributes to the neuromuscular control of challenging balance tasks.

  17. Motion control report

    CERN Document Server

    2013-01-01

    Please note this is a short discount publication. In today's manufacturing environment, Motion Control plays a major role in virtually every project.The Motion Control Report provides a comprehensive overview of the technology of Motion Control:* Design Considerations* Technologies* Methods to Control Motion* Examples of Motion Control in Systems* A Detailed Vendors List

  18. Reflex control of human jaw muscles.

    Science.gov (United States)

    Türker, Kemal S

    2002-01-01

    The aim of this review is to discuss what is known about the reflex control of the human masticatory system and to propose a method for standardized investigation. Literature regarding the current knowledge of activation of jaw muscles, receptors involved in the feedback control, and reflex pathways is discussed. The reflexes are discussed under the headings of the stimulation conditions. This was deliberately done to remind the reader that under each stimulation condition, several receptor systems are activated, and that it is not yet possible to stimulate only one afferent system in isolation in human mastication experiments. To achieve a method for uniform investigation, we need to set a method for stimulation of the afferent pathway under study with minimal simultaneous activation of other receptor systems. This stimulation should also be done in an efficient and reproducible way. To substantiate our conviction to standardize the stimulus type and parameters, we discuss the advantages and disadvantages of mechanical and electrical stimuli. For mechanical stimulus to be delivered in a reproducible way, the following precautions are suggested: The stimulus delivery system (often a probe attached to a vibrator) should be brought into secure contact with the area of stimulation. To minimize the slack between the probe, the area to be stimulated should be taken up by the application of pre-load, and the delivered force should be recorded in series. Electrical stimulus has advantages in that it can be delivered in a reproducible way, though its physiological relevance can be questioned. It is also necessary to standardize the method for recording and analyzing the responses of the motoneurons to the stimulation. For that, a new technique is introduced, and its advantages over the currently used methods are discussed. The new method can illustrate the synaptic potential that is induced in the motoneurons without the errors that are unavoidable in the current

  19. Academic strangeness as uncomfortable reflexivity and academic reflexivity as uncomfortable strangeness in higher education

    DEFF Research Database (Denmark)

    Fristrup, Tine; Tulinius, Charlotte; Hølge-Hazelton, Bibi

    2015-01-01

    strangeness among several of the students, but also among ourselves as teachers and facilitators. We have been inspired by the work done by Ruth Behar (1996) on becoming a vulnerable observer and the work done by Pranee Liamputtong (2006) on researching the vulnerable. Both approaches involve a critique....... The paper briefly describes the strategies used to plan, deliver and evaluate the course, but the main emphasis is on the learning taking place as a consequence of working within this area and using these strategies in the educational setting. Having participated in and studied academic and peer supervision...... for the course, as teachers, was to create ‘an academic zone of comfort’ at the course, something we had been deprived of ourselves as young researchers. Our insistence on continuous reflexivity regarding the uncomfortable in order to develop academic reflexivity among the students created uncomfortable academic...

  20. System identification of the human vestibulo-ocular reflex during head-free tracking.

    Science.gov (United States)

    Tangorra, James L; Jones, Lynette A; Hunter, Ian W

    2004-01-01

    A method was developed to identify the linear, system level dynamics of the horizontal, angular vestibulo-ocular reflex (VOR) as it stabilized vision during head-free tracking of a visual target. Small amplitude, broad spectrum, stochastic torque perturbations were applied to the head while the subject tracked an unpredictable, moving target with active head and eye motions. Stochastic system identification techniques were used to design the torque and target inputs and to conduct the analysis such that the linear dynamics of the VOR, independently of the visual system's influence on eye motions, were determined. The linear analysis was limited to evaluating VOR dynamics from approximately 0.5 to 4.5 Hz. Nonlinearities in the head-neck system affected the low frequency response of the head to the torque perturbations, and the eye velocity sequence was affected by nonlinearities and degraded by noise at high frequencies. The VOR's gain was near 1.0 between about 0.5 and 2.5 Hz, and then decreased steadily to 0.85 as the frequency increased towards 4.0 Hz. The VOR phase angle was also frequency dependent and corresponded to VOR eye motions lagging the head's disturbance motion by less than 10 ms at frequencies greater than 1.0 Hz.

  1. Reflexive regulation of CSR to promote sustainability

    DEFF Research Database (Denmark)

    Buhmann, Karin

    2011-01-01

    climate change and environmental sustainability, and social, economic and other human rights lend human rights as part of CSR a potential for meeting some environmental and climate concerns and handling adverse side-effects. The article analyses two EU initiatives: The EU Multi-Stakeholder (MSF) on CSR......This article discusses Corporate Social Responsibility (CSR) from the perspective of governmental regulation as a measure to promote public policy interests through public-private regulation intended to influence firms’ self-regulation. Presenting a ‘government case’ for CSR, the connection between...... and the EU CSR Alliance. Focusing on human rights based in international law, it analyses the patterns of negotiation in the MSF and the background for the launch of the CSR Alliance. It shows that analysing public-private regulation of CSR from the perspective of reflexive law theory assists us...

  2. Reflexive regulation of CSR to promote sustainablility

    DEFF Research Database (Denmark)

    Buhmann, Karin

    climate change and environmental sustainability, and social, economic and other human rights lend human rights as part of CSR a potential for meeting some environmental and climate concerns and handling adverse side-effects. The article analyses two EU initiatives: The EU Multi-Stakeholder (MSF) on CSR...... in promoting companies’ responsibility with regard to aspects of sustainable development, such as climate impact. Keywords: Sustainable development, sustainable companies, reflexive regulation, climate change, CSR, EU law, public-private regulation, companies' self-regulation......This article discusses Corporate Social Responsibility (CSR) from the perspective of governmental regulation as a measure to promote public policy interests through public-private regulation intended to influence firms’ self-regulation. Presenting a ‘government case’ for CSR, the connection between...

  3. Cultural reflexivity in health research and practice.

    Science.gov (United States)

    Aronowitz, Robert; Deener, Andrew; Keene, Danya; Schnittker, Jason; Tach, Laura

    2015-07-01

    Recent public health movements have invoked cultural change to improve health and reduce health disparities. We argue that these cultural discourses have sometimes justified and maintained health inequalities when those with power and authority designated their own social practices as legitimate and healthy while labeling the practices of marginalized groups as illegitimate or unhealthy. This "misrecognition," which creates seemingly objective knowledge without understanding historical and social conditions, sustains unequal power dynamics and obscures the fact that what is deemed legitimate and healthy can be temporally, geographically, and socially relative. We use examples from research across multiple disciplines to illustrate the potential consequences of cultural misrecognition, highlight instances in which culture was invoked in ways that overcame misrecognition, and discuss how cultural reflexivity can be used to improve health research and practice.

  4. The Chinchilla's vestibulo-ocular reflex

    Science.gov (United States)

    Merwin, W. H., Jr.; Wall, Conrad, III; Tomko, D. L.

    1989-01-01

    The horizontal vestibulo-ocular reflex (VOR) was measured and characterized in seven adult chinchillas using 0.01 to 1.0 Hz angular velocity sinusoids. Gains were less than compensatory, and were variable from day to day, but phases were highly repeatable both within and between animals. The best fitting transfer function to the average data of all animals had a dominant time constant of 7.5 sec, and an adaptation operator with a time constant of 24.0 sec. There were certain nonlinearities in the horizontal VOR of this animal, and it was difficult to elicit a robust optokinetic response. Results are discussed in relation to similar measurements in other species.

  5. Is there a hierarchy of survival reflexes?

    Science.gov (United States)

    Macphail, Kieran

    2013-10-01

    A hierarchy of survival reflexes for prioritising assessment and treatment in patients with pain of insidious onset is hypothesised. The hierarchy asserts that some systems are more vital than others and that the central nervous system (CNS) prioritises systems based on their significance to survival. The hypothesis suggests that dysfunction in more important systems will cause compensation in less important systems. This paper presents studies examining these effects for each system, arguing that each section of the hierarchy may have effects on other systems within the hierarchy. This concept is untested empirically, highly speculative and substantial research is required to validate the suggested hierarchical prioritisation by the CNS. Nonetheless, the hierarchy does provide a theoretical framework to use to exclude contributing systems in patients with pain of insidious onset. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. The Disappearing Audience and Reflexive Visibility

    Directory of Open Access Journals (Sweden)

    Katerina Girginova

    2016-08-01

    Full Text Available Contrary to popular opinion and some academic writing that celebrates the renewed visibility of new media audiences, this essay argues that they are increasingly going into retreat. To understand how new media audiences “disappear” from view of one another, I borrow from Brighenti’s typology of visibility and develop the idea of “reflexive visibility.” The latter describes the ability to socially orient ourselves in a digital environment through the textual and contextual cues of others—an activity that is of utmost importance not only to researchers wishing to “see” various audiences but also for audiences writ large, wishing to know themselves.

  7. Conditioning the middle ear reflex at sensation levels below reflex threshold: air jet and electrical stimulation.

    Science.gov (United States)

    McDaniel-Bacon, L; Fulton, R T; Laskowski, R P

    1980-01-01

    An ABAB functional analysis, conditioning and generalization, design was used in 3 experiments (2 were formal studies and 1 was empirical in nature) to investigate the conditionability of the middle ear reflex. The conditioned stimuli were subreflex threshold pure tones of various frequencies and intensities. The unconditioned stimulus (UCS) was an auricular air jet to the contralateral ear in the first experiment and cutaneous electrical stimulation to the ipsolateral, probe ear in the last 2 experiments. Reflexes were monitored by an otoadmittance meter, storage oscilloscope, and strip chart recorder. In the first experiment (air jet UCS), no subjects met the conditioning criterion within the maximum presentation of 400 paired trials, despite pilot evidence which indicated conditioning was feasible. In the second experiment (electrical stimulation UCS), 2 subjects met conditioning criterion; however, only one subject reconditioned and demonstrated partial generalization to other conditioned stimuli. In the third experiment (electrical stimulation UCS), one of 3 subjects who had previously been unconditionable with the air jet UCS met conditioning and reconditioning criterion and demonstrated partial generalization. Results indicate that the middle ear reflex can be conditioned to be elicited by subreflex threshold pure tones, however, results are limited.

  8. Somatosensory imprinting in spinal reflex modules.

    Science.gov (United States)

    Schouenborg, Jens

    2003-05-01

    Understanding how sensory information is used by motor systems for motor commands requires detailed knowledge about how the body shape and biomechanics are represented in the motor circuits. We have used the withdrawal reflex system as a model for studies of sensorimotor transformation. This system has a modular organisation in the adult. Each module performs a detailed and functionally adapted sensorimotor transformation related to the withdrawal efficacy of its output muscle(s). The weight distribution of the cutaneous input to a module is determined by the pattern of withdrawal efficacy of the muscle. Recently, we found that the somatotopic organisation and weight of the cutaneous input to the dorsal horn of the lower lumbar cord is related to this modular organisation. The dorsal horn in the lower lumbar cord thus appears to be organised in a column-like fashion, where each column performs a basic sensorimotor transformation related to the movement caused by a single muscle and the body shape. Since the withdrawal reflex system encodes error signals to the cerebellum through some of the spino-olivo cerebellar pathways, the modular concept is, in fact, a key to understanding sensory processing in higher order motor systems as well. Developmental studies indicate that each module is a self-organising circuitry that uses sensory feedback on muscle contractions to adjust its synaptic organisation. Furthermore, these studies suggest that the spontaneous movements during development, by providing structured sensory information related to movement pattern of single muscles and body shape, are instrumental in shaping the sensorimotor transformation in the spinal cord. These findings and their implications for the understanding of higher motor functions and their clinical aspects will be discussed.

  9. Neural Mechanisms of Illusory Motion: Evidence from ERP Study

    Directory of Open Access Journals (Sweden)

    Xu Y. A. N. Yun

    2011-05-01

    Full Text Available ERPs were used to examine the neural correlates of illusory motion, by presenting the Rice Wave illusion (CI, its two variants (WI and NI and a real motion video (RM. Results showed that: Firstly, RM elicited a more negative deflection than CI, NI and WI between 200–350ms. Secondly, between 500–600ms, CI elicited a more positive deflection than NI and WI, and RM elicited a more positive deflection than CI, what's more interesting was the sequential enhancement of brain activity with the corresponding motion strength. We inferred that the former component might reflect the successful encoding of the local motion signals in detectors at the lower stage; while the latter one might be involved in the intensive representations of visual input in real/illusory motion perception, this was the whole motion-signal organization in the later stage of motion perception. Finally, between 1185–1450 ms, a significant positive component was found between illusory/real motion tasks than NI (no motion. Overall, we demonstrated that there was a stronger deflection under the corresponding lager motion strength. These results reflected not only the different temporal patterns between illusory and real motion but also extending to their distinguishing working memory representation and storage.

  10. Stereomotion speed perception is contrast dependent

    Science.gov (United States)

    Brooks, K.

    2001-01-01

    The effect of contrast on the perception of stimulus speed for stereomotion and monocular lateral motion was investigated for successive matches in random-dot stimuli. The familiar 'Thompson effect'--that a reduction in contrast leads to a reduction in perceived speed--was found in similar proportions for both binocular images moving in depth, and for monocular images translating laterally. This result is consistent with the idea that the monocular motion system has a significant input to the stereomotion system, and dominates the speed percept for approaching motion.

  11. Modification of cutaneous reflexes during visually guided walking.

    Science.gov (United States)

    Ruff, Casey R; Miller, Andreas B; Delva, Mona L; Lajoie, Kim; Marigold, Daniel S

    2014-01-01

    Although it has become apparent that cutaneous reflexes can be adjusted based on the phase and context of the locomotor task, it is not clear to what extent these reflexes are regulated when locomotion is modified under visual guidance. To address this, we compared the amplitude of cutaneous reflexes while subjects performed walking tasks that required precise foot placement. In one experiment, subjects walked overground and across a horizontal ladder with narrow raised rungs. In another experiment, subjects walked and stepped onto a series of flat targets, which required different levels of precision (large vs. narrow targets). The superficial peroneal or tibial nerve was electrically stimulated in multiple phases of the gait cycle in each condition and experiment. Reflexes between 50 and 120 ms poststimulation were sorted into 10 equal phase bins, and the amplitudes were then averaged. In each experiment, differences in cutaneous reflexes between conditions occurred predominantly during swing phase when preparation for precise foot placement was necessary. For instance, large excitatory cutaneous reflexes in ipsilateral tibialis anterior were present in the ladder condition and when stepping on narrow targets compared with inhibitory responses in the other conditions, regardless of the nerve stimulated. In the ladder experiments, additional effects of walking condition were evident during stance phase when subjects had to balance on the narrow ladder rungs and may be related to threat and/or the unstable foot-surface interaction. Taken together, these results suggest that cutaneous reflexes are modified when visual feedback regarding the terrain is critical for successful walking.

  12. Avian reflex and electroencephalogram responses in different states of consciousness.

    Science.gov (United States)

    Sandercock, Dale A; Auckburally, Adam; Flaherty, Derek; Sandilands, Victoria; McKeegan, Dorothy E F

    2014-06-22

    Defining states of clinical consciousness in animals is important in veterinary anaesthesia and in studies of euthanasia and welfare assessment at slaughter. The aim of this study was to validate readily observable reflex responses in relation to different conscious states, as confirmed by EEG analysis, in two species of birds under laboratory conditions (35-week-old layer hens (n=12) and 11-week-old turkeys (n=10)). We evaluated clinical reflexes and characterised electroencephalograph (EEG) activity (as a measure of brain function) using spectral analyses in four different clinical states of consciousness: conscious (fully awake), semi-conscious (sedated), unconscious-optimal (general anaesthesia), unconscious-sub optimal (deep hypnotic state), as well as assessment immediately following euthanasia. Jaw or neck muscle tone was the most reliable reflex measure distinguishing between conscious and unconscious states. Pupillary reflex was consistently observed until respiratory arrest. Nictitating membrane reflex persisted for a short time (reflex is a conservative measure of death in poultry. Using spectral analyses of the EEG waveforms it was possible to readily distinguish between the different states of clinical consciousness. In all cases, when birds progressed from a conscious to unconscious state; total spectral power (PTOT) significantly increased, whereas median (F50) and spectral edge (F95) frequencies significantly decreased. This study demonstrates that EEG analysis can differentiate between clinical states (and loss of brain function at death) in birds and provides a unique integration of reflex responses and EEG activity. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Analysing responses to climate change through the lens of reflexivity.

    Science.gov (United States)

    Davidson, Debra

    2012-12-01

    Sociologists are increasingly directing attention toward social responses to climate change. As is true of any new field of inquiry, theoretical frameworks guiding the research to date have room for improvement. One advance could be achieved through closer engagement with Reflexivity Theory, particularly the work of Margaret Archer, who asks just how individuals come to give attention to certain problems, and formulate responses to them. Individuals vary significantly in regard to their understanding of and concern for anthropogenic climate change, and these standpoints in turn influence commitment to mitigation and adaptation. The emergent social interactions among all such agents in turn influence the morphogenetic trajectories through which social structures will evolve, but the role of 'meta-reflexives' is particularly crucial. Identifying pathways of individual climate change reflexivity can make a valuable contribution to our understanding of the potential for and nature of collective responses. In this paper, I explore climate change reflexivity, with particular attention to climate change meta-reflexives, through a qualitative analysis of personal interviews with residents of two small communities in Alberta, Canada. Applying Reflexivity Theory to this context articulates dimensions of reflexive processing not elaborated in current theoretical treatments, including future outlook and comfort with uncertainty, among others.

  14. Reflexes from the lungs and airways: historical perspective.

    Science.gov (United States)

    Widdicombe, John

    2006-08-01

    Historical aspects of respiratory reflexes from the lungs and airways are reviewed, up until about 10 yr ago. For most of the 19th century, the possible reflex inputs into the "respiratory center," the position of which had been identified, were very speculative. There was little concept of reflex control of the pattern of breathing. Then, in 1868, Breuer published his paper on "The self-steering of respiration via the Nervus Vagus." For the first time this established the role of vagal inflation and deflation reflexes in determining the pattern of breathing. Head later extended Breuer's work, and Kratschmer laid a similar basis for reflexes from the nose and larynx. Then, 50-60 yr later, the development of the thermionic valve and the oscilloscope allowed recording action potentials from single nerve fibers in the vagus. In 1933, Adrian showed that slowly adapting pulmonary stretch receptors were responsible for the inflation reflex. Later, Knowlton and Larrabee described rapidly adapting receptors and showed that they mediated deep augmented breaths and the deflation reflex. Still later, it was established that rapidly adapting receptors were, at least in part, responsible for cough. In 1954, Paintal began his study of C-fiber receptors (J receptors), work greatly extended by the Coleridges. Since approximately 10 yr ago, when the field of this review stops, there has been an explosion of research on lung and airway receptors, many aspects of which are dealt with in other papers in this series.

  15. Exercise-induced neuromuscular dysfunction under reflex conditions.

    Science.gov (United States)

    Kaufman, T; Burke, J R; Davis, J M; Durstine, J L

    2001-06-01

    The purpose of this research was to describe further the effects of exercise-induced muscle damage on reflex sensitivity. The subjects were eight physically active, but untrained males, between the ages of 18 and 29 years. The effects of eccentric and concentric exercise on patellar tendon reflex responses were determined. The 8 week experiment consisted of two, 5 day, test protocols with a 6 week wash-out period between test protocols. Each 5 day test protocol consisted of the following six test sessions: (1) day 1--baseline, (2) day 2 baseline, (3) day 2--immediate post-exercise, and (4-6) days 3-5: 24, 48, and 72 h post-exercise. On day 2, the subjects made either 100 fatiguing concentric or eccentric isotonic contractions using the right leg at 75% of the corresponding repetition maximum values. During each test session, the electromyogram (EMG) and force-time characteristics of basic and conditioned patellar tendon reflex responses were measured. The reflex amplitudes of basic and conditioned patellar tendon reflex responses were decreased following fatiguing concentric exercise. There were no immediate effects of fatiguing eccentric exercise on the basic and conditioned patellar tendon reflex responses, but the EMG amplitudes of these reflex responses were reduced on the days following eccentric exercise. The amount of conditioned patellar tendon reflex facilitation was decreased following the concentric exercise protocol and at 48 h post-eccentric exercise. Our conditioned reflex data suggest that post-exercise changes to the physiological mechanisms that modulate the recruitment gain of the alpha-motoneuron pool may depend upon the type of fatiguing exercise.

  16. Interindividual differences in H reflex modulation during normal walking.

    Science.gov (United States)

    Simonsen, Erik B; Dyhre-Poulsen, Poul; Alkjaer, Tine; Aagaard, Per; Magnusson, S Peter

    2002-01-01

    Based on previous studies, at least two different types of soleus Hoffmann (H) reflex modulation were likely to be found during normal human walking. Accordingly, the aim of the present study was to identify different patterns of modulation of the soleus H reflex and to examine whether or not subjects with different H reflex modulation would exhibit different walking mechanics and different EMG activity. Fifteen subjects walked across two force platforms at 4.5 km/h (+/-10%) while the movements were recorded on video. The soleus H reflex and EMG activity were recorded separately during treadmill walking at 4.5 km/h. Using a two-dimensional analysis joint angles, angular velocities, accelerations, linear velocities and accelerations were calculated, and net joint moments about the ankle, knee and hip joint were computed by inverse dynamics from the video and force plate data. Six subjects (group S) showed a suppressed H reflex during the swing phase, and 9 subjects (group LS) showed increasing reflex excitability during the swing phase. The plantar flexor dominated moment about the ankle joint was greater for group LS. In contrast, the extensor dominated moment about the knee joint was greater for the S group. The hip joint moment was similar for the groups. The EMG activity in the vastus lateralis and anterior tibial muscles was greater prior to heel strike for the S group. These data indicate that human walking exhibits at least two different motor patterns as evaluated by gating of afferent input to the spinal cord, by EMG activity and by walking mechanics. Increasing H reflex excitability during the swing phase appears to protect the subject against unexpected perturbations around heel strike by a facilitated stretch reflex in the triceps surae muscle. Alternatively, in subjects with a suppressed H reflex in the swing phase the knee joint extensors seem to form the primary protection around heel strike.

  17. Perceptual costs for motion transparency evaluated by two performance measures.

    Science.gov (United States)

    Suzuki, Naoto; Watanabe, Osamu

    2009-08-01

    Transparency perception is recognized as one of the important phenomena to understand the computational mechanism of early visual system. Transparency perception indicates that a simple theory reconstructing a single-valued field of a visual attribute, such as an optical-flow field, cannot model the neural mechanism for the human visual system and raises a fundamental issue of how visual attributes are represented and detected in the brain. It is considered that one of the important cues to reveal the neural encoding mechanism for overlapping surfaces is the perceptual cost in transparency perception. It has been known that the perceptual performance in motion transparency is worse than that expected from single motion perception. This perceptual "cost" would reflect the encoding strategy for transparent motions. Here we present a systematic study comparing the perceptual costs in motion transparency evaluated by two performance measures. The result showed that the properties of the perceptual costs varied with the performance measures. The perceptual cost evaluated by the motion detection threshold became smaller as a directional difference between overlapping motions increased, whereas the cost examined with the precision of directional judgments became worse. A computational analysis suggests that these contradictory results cannot be explained by a simple population coding model for motion directions.

  18. Atypical Pupillary Light Reflex in Individuals with Autism

    Science.gov (United States)

    2014-09-01

    AWARD NUMBER: W81XWH-10-1-0474 TITLE: Atypical Pupillary Light Reflex in Individuals with Autism ...30th/2014 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER W81XWH-10-1-0474 Atypical Pupillary  Light  Reflex in Individuals with  Autism 5b. GRANT NUMBER...20,  p< .00005 in all instances].  15. SUBJECT TERMS Pupillary light reflex, autism , functional MRI 16. SECURITY CLASSIFICATION OF: 17

  19. [Human physiology: images and practices of the reflex].

    Science.gov (United States)

    Wübben, Yvonne

    2010-01-01

    The essay examines the function of visualizations and practices in the formation of the reflex concept from Thomas Willis to Marshall Hall. It focuses on the specific form of reflex knowledge that images and practices can contain. In addition, the essay argues that it is through visual representations and experimental practices that technical knowledge is transferred to the field of human reflex physiology. When using technical metaphors in human physiology authors often seem to feel obliged to draw distinctions between humans, machines and animals. On closer scrutiny, these distinctions sometimes fail to establish firm borders between the human and the technical.

  20. Development of sensory motor reflexes in 2 G exposed rats.

    Science.gov (United States)

    Wubbels, Réne; Bouët, Valentine; de Jong, Herman; Gramsbergen, Albert

    2004-07-01

    During gestation and early postnatal development, the animal's size and weight rapidly increase. Within that period, gravity affects sensory and motor development. We studied age-dependent modifications of several types of motor reflexes in 5 groups of rats conceived, born and reared in hypergravity (HG; 2 g). These rats were transferred to normal gravity (NG; 1 g) at various postnatal days, and their behavioral reflexes were compared with a control group which was constantly kept under NG. HG induced a retarded development of vestibular dependent reflexes. Other types of motor behavior were not delayed.

  1. The statistics of the vestibular input experienced during natural self-motion differ between rodents and primates.

    Science.gov (United States)

    Carriot, Jérome; Jamali, Mohsen; Chacron, Maurice J; Cullen, Kathleen E

    2017-04-15

    In order to understand how the brain's coding strategies are adapted to the statistics of the sensory stimuli experienced during everyday life, the use of animal models is essential. Mice and non-human primates have become common models for furthering our knowledge of the neuronal coding of natural stimuli, but differences in their natural environments and behavioural repertoire may impact optimal coding strategies. Here we investigated the structure and statistics of the vestibular input experienced by mice versus non-human primates during natural behaviours, and found important differences. Our data establish that the structure and statistics of natural signals in non-human primates more closely resemble those observed previously in humans, suggesting similar coding strategies for incoming vestibular input. These results help us understand how the effects of active sensing and biomechanics will differentially shape the statistics of vestibular stimuli across species, and have important implications for sensory coding in other systems. It is widely believed that sensory systems are adapted to the statistical structure of natural stimuli, thereby optimizing coding. Recent evidence suggests that this is also the case for the vestibular system, which senses self-motion and in turn contributes to essential brain functions ranging from the most automatic reflexes to spatial perception and motor coordination. However, little is known about the statistics of self-motion stimuli actually experienced by freely moving animals in their natural environments. Accordingly, here we examined the natural self-motion signals experienced by mice and monkeys: two species commonly used to study vestibular neural coding. First, we found that probability distributions for all six dimensions of motion (three rotations, three translations) in both species deviated from normality due to long tails. Interestingly, the power spectra of natural rotational stimuli displayed similar structure

  2. Functional Organization of Social Perception and Cognition in the Superior Temporal Sulcus

    National Research Council Canada - National Science Library

    Deen, Ben; Koldewyn, Kami; Kanwisher, Nancy; Saxe, Rebecca

    2015-01-01

    The superior temporal sulcus (STS) is considered a hub for social perception and cognition, including the perception of faces and human motion, as well as understanding others' actions, mental states, and language...

  3. Primitive Reflexes and Attention-Deficit/Hyperactivity Disorder: Developmental Origins of Classroom Dysfunction

    Science.gov (United States)

    Taylor, Myra; Houghton, Stephen; Chapman, Elaine

    2004-01-01

    The present research studied the symptomatologic overlap of AD/HD behaviours and retention of four primitive reflexes (Moro, Tonic Labyrinthine Reflex [TLR], Asymmetrical Tonic Neck Reflex [ATNR], Symmetrical Tonic Neck Reflex [STNR]) in 109 boys aged 7-10 years. Of these, 54 were diagnosed with AD/HD, 34 manifested sub-syndromal coordination,…

  4. Motion, frames of reference, dead horses, and metaphysics (comment on Stoffregen & Bardy, 2001)

    NARCIS (Netherlands)

    Wertheim, A.H.

    2001-01-01

    Various annoyingly incorrect statements of Stoffregen & Bardy are corrected, for example, that perception researchers commonly use the term "absolute motion" to denote motion without any frame of reference, confuse earth-relative and gravity-relative motion, err with respect to the frame of

  5. Motion and Actions in Language: Semantic Representations in Occipito-Temporal Cortex

    Science.gov (United States)

    Humphreys, Gina F.; Newling, Katherine; Jennings, Caroline; Gennari, Silvia P.

    2013-01-01

    Understanding verbs typically activates posterior temporal regions and, in some circumstances, motion perception area V5. However, the nature and role of this activation remains unclear: does language alone indeed activate V5? And are posterior temporal representations modality-specific motion representations, or supra-modal motion-independent…

  6. Motion, frames of reference, dead horses, and metaphysics (comment on Stoffregen & Bardy, 2001)

    NARCIS (Netherlands)

    Wertheim, A.H.

    2001-01-01

    Various annoyingly incorrect statements of Stoffregen & Bardy are corrected, for example, that perception researchers commonly use the term "absolute motion" to denote motion without any frame of reference, confuse earth-relative and gravity-relative motion, err with respect to the frame of referenc

  7. Effects of repeated Achilles tendon vibration on triceps surae stiffness and reflex excitability.

    Science.gov (United States)

    Lapole, Thomas; Pérot, Chantal

    2011-02-01

    Clinical studies frequently report an increase in stiffness and a loss of range of motion at joints placed in disuse or immobilization. This is notably the case for subjects maintained in bed for a long period, whilst their joints are not affected. Recently we documented on healthy subjects the benefit in terms of force and activation capacities of the triceps surae offered by vibrations applied to the Achilles tendon. Knowing that stiffness changes may contribute to force changes, the aim of the present study was to investigate the effects of tendon vibration on the triceps surae stiffness of healthy subjects. The vibration program consisted in 14 days of 1h daily Achilles tendon vibration applied at rest. Nineteen healthy students were involved in this study. Before and at the end of the vibration program, musculo-tendinous stiffness in active conditions was determined by use of a quick-release test. Passive stiffness was also analyzed by a flexibility test: passive torque-angle relationships were established from maximal plantar-flexion to maximal dorsiflexion. Passive stiffness indexes at 10°, 15° and 20° dorsiflexion were defined as the slope of the relationships at the corresponding angle. Tendinous reflex, influenced by stiffness values, was also investigated as well as the H reflex to obtain an index of the central reflex excitability. After the program, musculo-tendinous stiffness was significantly decreased (p=.01). At the same time, maximal passive dorsiflexion was increased (p=.005) and passive stiffness indexes at 10°, 15° and 20° dorsiflexion decreased (ptriceps surae parameters are diminished after the vibration program, it could be beneficial to immobilized persons as hypo-activity is known to increase muscular stiffness.

  8. Motion in radiotherapy

    DEFF Research Database (Denmark)

    Korreman, Stine Sofia

    2012-01-01

    This review considers the management of motion in photon radiation therapy. An overview is given of magnitudes and variability of motion of various structures and organs, and how the motion affects images by producing artifacts and blurring. Imaging of motion is described, including 4DCT and 4DPET...

  9. Quantified reflex strategy using an iPod as a wireless accelerometer application.

    Science.gov (United States)

    LeMoyne, Robert; Mastroianni, Timothy; Grundfest, Warren

    2012-01-01

    A primary aspect of a neurological evaluation is the deep tendon reflex, frequently observed through the patellar tendon reflex. The reflex response provides preliminary insight as to the status of the nervous system. A quantified reflex strategy has been developed, tested, and evaluated though the use of an iPod as a wireless accelerometer application integrated with a potential energy device to evoke the patellar tendon reflex. The iPod functions as a wireless accelerometer equipped with robust software, data storage, and the capacity to transmit the recorded accelerometer waveform of the reflex response wirelessly through email for post-processing. The primary feature of the reflex response acceleration waveform is the maximum acceleration achieved subsequent to evoking the patellar tendon reflex. The quantified reflex strategy using an iPod as a wireless accelerometer application yields accurate and consistent quantification of the reflex response.

  10. Moving from spatially segregated to transparent motion: A modelling approach.

    Science.gov (United States)

    Durant, Szonya; Donoso-Barrera, Alejandra; Tan, Sovira; Johnston, Alan

    2006-03-22

    Motion transparency, in which patterns of moving elements group together to give the impression of lacy overlapping surfaces, provides an important challenge to models of motion perception. It has been suggested that we perceive transparent motion when the shape of the velocity histogram of the stimulus is bimodal. To investigate this further, random-dot kinematogram motion sequences were created to simulate segregated (perceptually spatially separated) and transparent (perceptually overlapping) motion. The motion sequences were analysed using the multi-channel gradient model (McGM) to obtain the speed and direction at every pixel of each frame of the motion sequences. The velocity histograms obtained were found to be quantitatively similar and all were bimodal. However, the spatial and temporal properties of the velocity field differed between segregated and transparent stimuli. Transparent stimuli produced patches of rightward and leftward motion that varied in location over time. This demonstrates that we can successfully differentiate between these two types of motion on the basis of the time varying local velocity field. However, the percept of motion transparency cannot be based simply on the presence of a bimodal velocity histogram.

  11. Sensory and circuit mechanisms mediating lower urinary tract reflexes.

    Science.gov (United States)

    Danziger, Zachary C; Grill, Warren M

    2016-10-01

    Neural control of continence and micturition is distributed over a network of interconnected reflexes. These reflexes integrate sensory information from the bladder and urethra and are modulated by descending influences to produce different physiological outcomes based on the information arriving from peripheral afferents. Therefore, the mode of activation of primary afferents is essential in understanding the action of spinal reflex pathways in the lower urinary tract. We present an overview of sensory mechanisms in the bladder and urethra focusing on their spinal integration, identify the cardinal spinal reflexes responsible for continence and micturition, and describe how their functional role is controlled via peripheral afferent activity. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Trigemino-cervical reflex in patients with headache.

    Science.gov (United States)

    Milanov, I; Bogdanova, D

    2003-02-01

    Neurophysiological studies have shown abnormal activity of some brainstem nuclei in headache patients. The trigemino-cervical reflex is an anti-nociceptive reflex that gives an opportunity for evaluation of the brainstem interneurone activity. It has not been previously examined in headache patients. We studied 15 patients with predominantly unilateral chronic tension-type headache, 15 patients with migraine without aura and 32 healthy subjects. The trigemino-cervical reflex was recorded bilaterally from the resting sternocleidomastoid muscle using surface electromyographic recordings. In all headache patients the trigemino-cervical reflex on the painful side was with shortened latency compared with the non-painful side and with healthy persons. The results suggest decreased activity of the brainstem inhibitory interneurones. We suggest that although the pathophysiological mechanisms of tension-type headache and migraine are different, they share common mechanisms of abnormal pain control.

  13. Interindividual differences in H reflex modulation during normal walking

    DEFF Research Database (Denmark)

    Simonsen, Erik B; Dyhre-Poulsen, Poul; Alkjaer, T

    2002-01-01

    Based on previous studies, at least two different types of soleus Hoffmann (H) reflex modulation were likely to be found during normal human walking. Accordingly, the aim of the present study was to identify different patterns of modulation of the soleus H reflex and to examine whether...... or not subjects with different H reflex modulation would exhibit different walking mechanics and different EMG activity. Fifteen subjects walked across two force platforms at 4.5 km/h (+/-10%) while the movements were recorded on video. The soleus H reflex and EMG activity were recorded separately during...... treadmill walking at 4.5 km/h. Using a two-dimensional analysis joint angles, angular velocities, accelerations, linear velocities and accelerations were calculated, and net joint moments about the ankle, knee and hip joint were computed by inverse dynamics from the video and force plate data. Six subjects...

  14. On the gastrocecal inhibitory reflex in the rat.

    Directory of Open Access Journals (Sweden)

    Lee,Zai-Liu

    1981-11-01

    Full Text Available In rats anesthetized with urethane, the effects of distention of the stomach upon cecal motility and neural mechanisms which generate this effect were studied. Cecal motility was inhibited which generate this effect were studied. Cecal motility was inhibited when the pars glandularis of the stomach was distended by pressure ranging from 25 to 30 cm H2O. This inhibitory reflex was not affected by bilateral cervical vagotomy, but completely abolished following bilateral severance of the greater splanchnic nerves or after intravenous administration of guanethidine. After transection of the spinal cord at the level of the 5th thoracic segment the inhibitory reflex remained intact, but was abolished following pithing of the 6th thoracic segment and below. It may be concluded that the afferent and efferent path of the gastrocecal inhibitory reflex mainly pass through the greater splanchnic nerves and the reflex center is located in thoracic segments caudal to the 6th thoracic segment.

  15. Reflexive Pronouns in Dagbani Samuel Alhassan Issah1 Abstract ...

    African Journals Online (AJOL)

    ... this paper. 1 Samuel Alhassan Issah teaches at the University of Education, Winneba. ..... This seems to suggest that the reflexive pronouns of Mandarian Chinese ... pronouns of Russian which are also argued to be non-local as argued by.

  16. Kinesio Taping in Young Healthy Subjects Does Not Affect Postural Reflex Reactions and Anticipatory Postural Adjustments of the Trunk: A Pilot Study

    OpenAIRE

    Voglar, Matej; Sarabon, Nejc

    2014-01-01

    Therapeutic Kinesio Taping method is used for treatment of various musculo-skeletal conditions. Kinesio Taping might have some small clinically important beneficial effects on range of motion and strength but findings about the effects on proprioception and muscle activation are inconsistent. The aim of this study was to test if Kinesio Taping influences anticipatory postural adjustments and postural reflex reactions. To test the hypothesis twelve healthy young participants were recruited in ...

  17. Neuroanatomical basis of Sandifer's syndrome: a new vagal reflex?

    Science.gov (United States)

    Cerimagic, Denis; Ivkic, Goran; Bilic, Ervina

    2008-01-01

    Sandifer's syndrome is a gastrointestinal disorder with neurological features. It is characterized by reflex torticollis following deglutition in patients with gastroesophageal reflux and/or hiatal hernia. The authors believe that neurological manifestations of the syndrome are the consequence of vagal reflex with the reflex center in nucleus tractus solitarii (NTS). Three models for the neuroanatomical basis of the hypothetic reflex arc are presented. In the first one the hypothetic reflex arc is based on the classic hypothesis of two components nervus accessorius (n.XI) - radix cranialis (RC) and radix spinalis (RS) The nervous impulses are transmitted by nervus vagus (n.X) general visceral afferent (GVA) fibers to NTS situated in medulla oblongata, then by interneuronal connections on nucleus ambiguus (NA) and nucleus dorsalis nervi vagi (NDX). Special visceral efferent fibers (SVE) impulses from NA are in part transferred to n.XI ramus externus (RE) (carrying the majority of general somatic efferent (GSE) fibers) via hypothetic anastomoses in the region of foramen jugulare. This leads to contraction of trapezius and sternocleidomastoideus muscles, and the occurrence of intermittent torticollis. In the second suggested neuroanatomical model the hypothetic reflex arc is organized in the absence of n.XI RC, the efferent part of the reflex arc continues as NA, which is motor nucleus of nervus glossopharyngeus (n.IX) and n.X in this case while distal roots of n.XI that appear at the level of the olivary nucleus lower edge represent n.X roots. In the third presented model the hypothetic reflex arc includes no jugular transfer and could be realized via interneuronal connections directly from NTS to the spinal motoneurons within nucleus radicis spinalis nervi accessorii (NRS n.XI) or from NA to NRS n.XI. The afferent segment of the postulated reflex arc in all three models is mediated via n.X. We conclude that Sandifer's syndrome is a clinical manifestation of another

  18. Estrogen attenuates the exercise pressor reflex in female cats.

    Science.gov (United States)

    Schmitt, Petra M; Kaufman, M P

    2003-10-01

    In humans, the pressor and muscle sympathetic nerve responses to static exercise are less in women than in men. The difference has been attributed to the effect of estrogen on the exercise pressor reflex. Estrogen receptors are abundant in areas of the dorsal horn receiving input from group III and IV muscle afferents, which comprise the sensory limb of the exercise pressor reflex arc. These findings prompted us to investigate the effect of estrogen on the spinal pathway of the exercise pressor reflex arc. Previously, we found that the threshold concentration of 17beta-estradiol needed to attenuate the exercise pressor reflex in male decerebrate cats was 10 microg/ml (Schmitt PM and Kaufman MP. J Appl Physiol 94: 1431-1436, 2003). The threshold concentration for female cats, however, is not known. Consequently, we applied 17beta-estradiol to a well covering the L6-S1 spinal cord in decerebrate female cats. The exercise pressor reflex was evoked by electrical stimulation of the L7 or S1 ventral root, a maneuver that caused the hindlimb muscles to contract statically. We found that the pressor response to contraction averaged 38 +/- 7 mmHg before the application of 17beta-estradiol (0.01 microg/ml) to the spinal cord, whereas it averaged only 23 +/- 4 mmHg 30 min after application (P effect on the exercise pressor reflex (n = 5). We conclude that the concentration of 17beta-estradiol required to attenuate the exercise pressor reflex is 1,000 times more dilute in female cats than that needed to attenuate this reflex in male cats.

  19. Impaired control of the oculomotor reflexes in Parkinson's disease

    OpenAIRE

    van Koningsbruggen, Martijn G.; Pender, Tom; Machado, Liana; Rafal, Robert D.

    2009-01-01

    To investigate the role of the basal ganglia in integrating voluntary and reflexive behaviour, the current study examined the ability of patients with Parkinson's disease to voluntarily control oculomotor reflexes. We measured the size of the fixation offset effect (the reduction in saccadic reaction time when a fixation point is removed) during a block of pro- and a block of anti-saccades. Healthy controls showed the expected reduction of the FOE during the anti-saccades, which results from ...

  20. An electronic device to record consensual reflex in human pupil.

    Science.gov (United States)

    Pinheiro, H M; Costa, R M; Camilo, E N R; Gang, Hua

    2015-01-01

    Examination of the pupil offers an objective evaluation of visual function as well as the vegetative pathways to the eye. This work proposes the development of an effective method and a portable device to test the consensual pupillary reflex. The first results demonstrate the success of a new device construction and methodology to record the consensual reflex with different stimulus, in a situation of complete blockage of light.