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One hundred and twenty years ago, the American philosopher and psychologist John Dewey published his seminal paper The Reflex Arc Concept in Psychology in the Psychological Review . In this essay Dewey claims that the model of a reflex... more
One hundred and twenty years ago, the American philosopher and psychologist John Dewey published his seminal paper The Reflex Arc Concept in Psychology in the Psychological Review . In this essay Dewey claims that the model of a reflex arc is a misguided and partial concept; “what we have is a circuit, not an arc or broken segment of a circle,” says Dewey, who termed this complete circuit coordination —a dynamic sensory-motor process that underlies perception. Despite extensive evidence demonstrating the necessary connection between action and sensation, the arc paradigm Dewey opposed remains to this day the guiding framework to which almost all neuroscientific endeavors adhere to. This bias stems from the prevailing experimental methodology and in particular, from the definitions of stimulus and response. Here we propose closed-loop methodology, complemented by Dewey's functional definitions of stimulus and response, as a possible framework for the advancement of the dynamical circuit interpretation.
Research Interests: Psychology and Perception
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Research Interests: Psychology, Cognitive Science, Psychophysics, Computer Science, Artificial Intelligence, and 15 moreComputer Vision, Perception, Motion perception, Medicine, Space perception, Visual Cortex, Humans, Illusion, Orientation, Saccades, Retina, Eye Movements, Optical Illusions, Receptive Field, and Eye Movement
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Research Interests: Neuroscience, Cognitive Science, Computer Science, Medicine, Brain Mapping, and 15 moreMovement, Animals, Male, Nature Neuroscience, Mechanoreceptors, Wakefulness, Anesthetics, Rats, Analysis of Variance, Time Factors, Reproducibility of Results, Hair Follicle, Neurosciences, Video Recording, and Biomechanical Phenomena
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Vibrissal location coding refers to the ways by which the location of external objects is coded (represented) in the vibrissal system of rodents. The vibrissal system contains the vibrissae (whiskers) and the follicles, neurons and... more
Vibrissal location coding refers to the ways by which the location of external objects is coded (represented) in the vibrissal system of rodents. The vibrissal system contains the vibrissae (whiskers) and the follicles, neurons and muscles associated with them. Coding is traditionally sub-categorized to encoding, i.e., coding at the whisker-object interaction phase, and recoding, i.e., coding at processing stages that are remote from this direct interaction. The vibrissal system is an active-sensing system—the system acquires information about objects in its environment by moving its whiskers (“whisking”, see Vibrissal behavior and function, Whisking kinematics) and interpreting the resulting sensations (Figure 1). In recent years, this system has attracted interest from researchers that study the emergence of perception from motor-sensory interactions and from engineers who regard whisking as a useful model system for developing robotic touch platforms, such as whiskered robots. This article reviews recent progress and our current understanding of vibrissal object location coding in rodents. Open image in new window Figure 1 Whisking behavior of freely-moving rats during two different tasks. Left and right C2 whiskers denoted in red and green, respectively. Top: Rhythmic whisking during whisking in air. Bottom: Whisking during an object localization task. Contact periods denoted by thick lines
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Research Interests: Neuroscience, Computer Science, Artificial Intelligence, Computer Vision, Medicine, and 15 moreDiscrimination Learning, Sensation, Movement, Animals, Male, Head Movements, Rats, Time Factors, Wistar Rats, Metronome, Hyperacuity, Object Localization, Whisker, Psychology and Cognitive Sciences, and Medical and Health Sciences
It has long been debated how humans resolve fine details and perceive a stable visual world despite the incessant fixational motion of their eyes. Current theories assume these processes to rely solely on the visual input to the retina,... more
It has long been debated how humans resolve fine details and perceive a stable visual world despite the incessant fixational motion of their eyes. Current theories assume these processes to rely solely on the visual input to the retina, without contributions from motor and/or proprioceptive sources. Here we show that contrary to this widespread assumption, the visual system has access to high-resolution extra-retinal knowledge of fixational eye motion and uses it to deduce spatial relations. Building on recent advances in gaze-contingent display control, we created a spatial discrimination task in which the stimulus configuration was entirely determined by oculomotor activity. Our results show that humans correctly infer geometrical relations in the absence of spatial information on the retina and accurately combine high-resolution extraretinal monitoring of gaze displacement with retinal signals. These findings reveal a sensory-motor strategy for encoding space, in which fine oculo...
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<p><b>A.</b> Angle trajectory from a contact trial, filtered at 80 Hz. Whisker C2 (red) touched the pole near the end of protraction. Touch events are indicated by black horizontal lines. TIPs (manually detected in this... more
<p><b>A.</b> Angle trajectory from a contact trial, filtered at 80 Hz. Whisker C2 (red) touched the pole near the end of protraction. Touch events are indicated by black horizontal lines. TIPs (manually detected in this example) are indicated by asterisks. The first touch depicted was also the first touch in the trial. Data for ipsilateral C2 (red), ipsilateral C1 (black), and contralateral C2 (blue) whiskers. <b>B.</b> Angle trajectory of whisks with TIP (red) and without (grey), all taken from a single trial. Time and angle are presented with respect to their values at touch onset. <b>C.</b> Example of a touch-induced pump (TIP) that, after contact between whisker C2 and the pole, occurred simultaneously in the three untrimmed whiskers (C1, C2, D1). The C2 whisker was continuously in contact with the pole throughout the period marked touch (bold red line), so the whisker palpates against the pole without detaching from it. The TIP peak or onset (indicated by the arrow), the time of the first peak after touch, is followed by negative velocity. <b>D.</b> Time from touch onset (start of red bold line in C) to TIP onset (arrow in C) in contact trials (purple). The average latency of touch-induced pumps was 17.9 ms. The distribution of times between pseudo-touches (crossing of a threshold angle in free-air trials) and pump onset was normalized to have the same number of touches as in the contact data and is denoted in green. <b>E.</b> Inter-pump-interval (time between touch onsets in two neighboring whisks-with-TIP) with experimental (purple) and simulated (control; green) data. The control distribution is what is expected if the pumps had the same probability to occur, but were distributed randomly upon touch events. The peak around 140 ms is due to pumps that occurred in successive whisks (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0044272#s2" target="_blank">Materials and Methods</a> for detailed description on the controls used in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0044272#pone-0044272-g003" target="_blank">Figs. 3D and 3E</a>).</p
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<p>Each statechart describes the behavior of an element of a certain type: (<b>A</b>) CPG (<b>B</b>) Neuron (<b>C</b>) Muscle (<b>D</b>) Whisker. The blue boxes indicate the states of... more
<p>Each statechart describes the behavior of an element of a certain type: (<b>A</b>) CPG (<b>B</b>) Neuron (<b>C</b>) Muscle (<b>D</b>) Whisker. The blue boxes indicate the states of the relevant element. The red arrows, together with the triggering events written next to them, describe the transitions between the states. Actions are indicated in gray. → points to the initial state upon model execution. © indicates a condition connector. tm(<i>X</i>) indicates a timeout of <i>X</i> msec; the values of the different <i>X</i> parameters are specified in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0079831#pone.0079831.s003" target="_blank">File S1</a>. When the model is executed, many copies of each statechart are generated, one for each of the actual components of the parent element. As the simulation advances, each component responds to various events by changing its states and parameter values accordingly, and by transmitting events to itself/other components.</p
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<div><p>(A and C) Oblique sections, dorsomedial to ventrolateral at 50° clockwise to the horizontal plane when the right hemisphere was viewed rostrally (Inset in [B]), through the thalamus of a young (postnatal day 7) (A) and... more
<div><p>(A and C) Oblique sections, dorsomedial to ventrolateral at 50° clockwise to the horizontal plane when the right hemisphere was viewed rostrally (Inset in [B]), through the thalamus of a young (postnatal day 7) (A) and an adult (340 g) (C) rat stained for CO. Depths from bregma were 2.9 mm for the dorsomedial and 3.6 mm for the ventrolateral end of the section shown in (A) and 4.4 mm and 5.85 mm, respectively, for the section shown in (C). Scale bars indicate 0.5 mm (A) and 1.0 mm (C). Arrows: R, rostral; DM, dorsomedial.</p> <p>(B and D) Borders between thalamic nuclei shown in (A) and (C), respectively, determined according to Paxinos and Watson's Atlas [<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0040124#pbio-0040124-b046" target="_blank">46</a>], using horizontal planes between 5.10 to 6.60 mm from bregma. Black dots in (D) indicate the projection of all recording sites ( <i>n</i> = 67) on the oblique plane. A–E barrelloids corresponding to whisker rows A–E, respectively. Arrows: L, lateral; VL, ventrolateral. </p> <p>Rt, reticular nucleus; VL, ventrolateral nucleus; VPL, ventroposterolateral nucleus.</p></div
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<p>(<b>A</b>) Example of whisking trajectory against an object of a single whisker (C2) in a head-fixed rat (filtered at 80 Hz). Whisker-object contact is indicated by bold. This example is a zoom-in of <a... more
<p>(<b>A</b>) Example of whisking trajectory against an object of a single whisker (C2) in a head-fixed rat (filtered at 80 Hz). Whisker-object contact is indicated by bold. This example is a zoom-in of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0079831#pone-0079831-g001" target="_blank">Figure 1D</a> in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0079831#pone.0079831-Deutsch1" target="_blank">[11]</a>. (<b>B</b>) Simulated TIPs in a single row as predicted by the “excitation of retractor MNs” configuration. While only whisker 4 touches an obstacle, all row's whiskers pump. At touch onset time, the touching whisker's angle is 74.7°, and the radial distance of contact is 40% of the whisker's length. TIP delay, relative to touch onset time: 17 msec; TIP retraction amplitude: ∼1° for all the non-touching whiskers, 0.6° for the touching whisker.</p
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<p>(A) TI value of each of the recorded neurons is indicated by a color code on its relative location in the canonical thalamic map defined in <a... more
<p>(A) TI value of each of the recorded neurons is indicated by a color code on its relative location in the canonical thalamic map defined in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0040124#pbio-0040124-g001" target="_blank">Figure 1</a>D. (B) Distribution of TI in VPMdm ( <i>n</i> = 30), VPMvl ( <i>n</i> = 13), and POm ( <i>n</i> = 24). </p
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<p>The presented values, of both the simulations and the rat, are of TIPs induced by contacts at a radial distance of 40% from the base of the touching whisker. Values of simulated TIPs that were induced by contacts at a wide range... more
<p>The presented values, of both the simulations and the rat, are of TIPs induced by contacts at a radial distance of 40% from the base of the touching whisker. Values of simulated TIPs that were induced by contacts at a wide range of radial distances (20–70%) are displayed in brackets. For each TIP-inducing mechanism, values were obtained while using either one of two whisking-evoking mechanisms: generation of whisking by CPG alone or by both the CPG and sensory feedback.</p>*<p>∼10° for all non-touching whiskers in rows A–E, except for the most rostral whiskers in rows C–E, which retracted by ∼5°.</p>**<p>Observed in both head-fixed and behaving rats. In head-fixed rats, TIP was observed in the two additional non-touching whiskers that where examined <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0079831#pone.0079831-Deutsch1" target="_blank">[11]</a>; in behaving rats TIP was observed in all the whiskers found on the same row as the touching whisker.</p
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<p>Examples of whisker trajectories (filtered at 80 Hz) from freely-moving rats performing a localization task <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0044272#pone.0044272-Knutsen1"... more
<p>Examples of whisker trajectories (filtered at 80 Hz) from freely-moving rats performing a localization task <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0044272#pone.0044272-Knutsen1" target="_blank">[6]</a>, demonstrating the occurrence of whisks with a single peak (gray) and multiple peaks (red) after contact onset.</p
Research Interests: Neuroscience and Moving
It has long been debated how humans resolve fine details and perceive a stable visual world despite the fixational motion of their eyes, the incessant ocular jitter that occurs in the intervals between voluntary gaze shifts. Current... more
It has long been debated how humans resolve fine details and perceive a stable visual world despite the fixational motion of their eyes, the incessant ocular jitter that occurs in the intervals between voluntary gaze shifts. Current theories assume these processes to rely solely on the visual input to the retina, without contributions from motor and/or proprioceptive sources. Here we show that contrary to this widespread assumption, the visual system has access to high-resolution extra-retinal knowledge of fixational eye motion and uses it to deduce spatial relations. Building on recent advances in gaze-contingent display control, we created a spatial discrimination task in which the stimulus configuration was entirely determined by oculomotor activity. Our results show that humans correctly infer geometrical relations even when no spatial information is delivered to the retina and accurately combine high-resolution extraretinal monitoring of gaze displacement with retinal signals. ...
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Significance Humans move their eyes continuously to scan their environment. Yet, the role of eye movements in object recognition is not known. In this work, we recorded eye movements of participants attempting to recognize images that are... more
Significance Humans move their eyes continuously to scan their environment. Yet, the role of eye movements in object recognition is not known. In this work, we recorded eye movements of participants attempting to recognize images that are just above and below the threshold of human recognition. To assess the contribution of retinal dynamics, we modeled the activation patterns resulting from the continuous interactions of eye movements with the viewed image. We then trained a classifier to differentiate recognized from unrecognized trials. We show that recognition could be classified only when the continuous interactions between eye movements and the image were used. We suggest that vision is mediated by continuous interactions between eye movements and the environment, resulting in dynamic oculo-retinal coding.
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Hand movements are essential for tactile perception of objects. However, the specific functions served by active touch strategies, and their dependence on physiological parameters, are unclear and understudied. Focusing on planar shape... more
Hand movements are essential for tactile perception of objects. However, the specific functions served by active touch strategies, and their dependence on physiological parameters, are unclear and understudied. Focusing on planar shape perception, we tracked at high resolution the hands of 11 participants during shape recognition task. Two dominant hand movement strategies were identified: contour following and scanning. Contour following movements were either tangential to the contour or oscillating perpendicular to it. Scanning movements crossed between distant parts of the shapes’ contour. Both strategies exhibited non-uniform coverage of the shapes’ contours. Idiosyncratic movement patterns were specific to the sensed object. In a second experiment, we have measured the participants’ spatial and temporal tactile thresholds. Significant portions of the variations in hand speed and in oscillation patterns could be explained by the idiosyncratic thresholds. Using data-driven simula...
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cial pad of the rat contains about 35 large whiskers,
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Hand movements are essential for tactile perception of objects. However, the specific functions served by active touch strategies, and their dependence on physiological parameters, is unclear and understudied. Focusing on planar shape... more
Hand movements are essential for tactile perception of objects. However, the specific functions served by active touch strategies, and their dependence on physiological parameters, is unclear and understudied. Focusing on planar shape perception, we tracked at high resolution the hands of eleven participants during shape recognition task. Two dominant hand movements strategies were identified: Contour-following movements, either tangential to the contour or oscillating perpendicular to it, and exploration by scanning movements, crossing between distant parts of the shapes’ contour. Both strategies exhibited non-uniform coverage of the shapes’ contours. Idiosyncratic movement patterns were specific to the sensed object and could be explained in part by spatial and temporal tactile thresholds of the participant. Using simulations, we show how some strategy choices may affect receptors activation. These results suggest that motion strategies of active touch adapt to both the sensed obj...
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ABSTRACTHand movements are essential for tactile perception of objects. However, why different individuals converge on specific movement patterns is not yet clear. Focusing on planar shape perception, we tracked the hands of 11... more
ABSTRACTHand movements are essential for tactile perception of objects. However, why different individuals converge on specific movement patterns is not yet clear. Focusing on planar shape perception, we tracked the hands of 11 participants while they practiced shape recognition. Our results show that planar shape perception is mediated by contour-following movements, either tangential to the contour or spatially-oscillating perpendicular to it, and by scanning movements, crossing between distant parts of the shapes’ contour. Both strategies exhibited non-uniform coverage of the shapes’ contours. We found that choice of strategy during the first experimental session was strongly correlated with two idiosyncratic parameters: participants with lower tactile resolution tended to move faster; and faster-adapting participants tended to employ oscillatory movements more often. In addition, practicing on isolated geometric features increased the tendency to use the contour-following strate...
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Animals actively move their sensory organs in order to acquire sensory information. Some rodents, such as mice and rats, employ cyclic scanning motions of their facial whiskers to explore their proximal surrounding, a behavior known as... more
Animals actively move their sensory organs in order to acquire sensory information. Some rodents, such as mice and rats, employ cyclic scanning motions of their facial whiskers to explore their proximal surrounding, a behavior known as whisking. Here we investigated the contingency of whisking kinematics on the animal’s behavioral context that arises from both internal processes (attention and expectations) and external constraints (available sensory and motor degrees of freedom). We recorded rat whisking at high temporal resolution in two experimental contexts - freely moving or head-fixed – and two spatial sensory configurations – a single row or three caudal whiskers on each side of the snout. We found that rapid sensorimotor twitches, called pumps, occurring during free-air whisking carry information about the rat’s upcoming exploratory direction, as demonstrated by the ability of these pumps to predict consequent head and body locomotion. Specifically, pump behavior during both...
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Physics and neuroscience share overlapping objectives, the major of which is probably the attempt to reduce the observed universe to a set of rules. The approaches are complementary, attempting to find a reduced description of the... more
Physics and neuroscience share overlapping objectives, the major of which is probably the attempt to reduce the observed universe to a set of rules. The approaches are complementary, attempting to find a reduced description of the universe or of the observer, respectively. We propose here that combining the two approaches within an observer-inclusive physical scheme, bears significant advantages. In such a scheme, the same set of rules applies to the universe and its observers, and the two descriptions are entangled. We show here that analyzing special relativity in an observer-inclusive framework can resolve its contradiction with the observed non-locality of physical interactions. The contradiction is resolved by reducing the universe (including the observer) to a dynamic distribution of closed strings (“ceons”) whose vibration waves travel at c. This ceons model is consistent with special and general relativity, non-locality and the holographic principle; it also eliminates Zeno’...
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THE DOWLOAD IS THE BOOK FRONT MATTER ONLY SEE LINKS FOR FULL TEXT. Touch is the ability to understand the world through physical contact. The noun “touch” and the verb “to touch” derive from the Old French verb “tochier”. Touch... more
THE DOWLOAD IS THE BOOK FRONT MATTER ONLY SEE LINKS FOR FULL TEXT. Touch is the ability to understand the world through physical contact. The noun “touch” and the verb “to touch” derive from the Old French verb “tochier”. Touch perception is also described by the adjectives tactile, from the Latin “tactilis”, and haptic, from the Greek “haptόs”. Academic research concerned with touch is also often described as haptics.
The aim of Scholarpedia of Touch, first published by Scholarpedia (www. scholarpedia.org), is to provide a comprehensive set of articles, written by leading researchers and peer reviewed by fellow scientists, detailing the current scientific understanding of the sense of touch and of its neural substrates in animals including humans. It is hoped that the encyclopedia will encourage sharing of ideas and insights between researchers working on different aspects of touch in different species, including research in synthetic touch systems. In addition, it is hoped that the encyclopedia will raise awareness about research in tactile sensing and promote increased scientific and public interest in the field.
The aim of Scholarpedia of Touch, first published by Scholarpedia (www. scholarpedia.org), is to provide a comprehensive set of articles, written by leading researchers and peer reviewed by fellow scientists, detailing the current scientific understanding of the sense of touch and of its neural substrates in animals including humans. It is hoped that the encyclopedia will encourage sharing of ideas and insights between researchers working on different aspects of touch in different species, including research in synthetic touch systems. In addition, it is hoped that the encyclopedia will raise awareness about research in tactile sensing and promote increased scientific and public interest in the field.