All have merit but they are dispersed across a wide literature and rarely are the findings integrated and synthesized in a meaningful way. The strength of the aperture effect was quantified by the degree to which the perceived direction was biased toward the direction orthogonal to the bars' orientation. Short-term plasticity in adult somatosensory cortex M. This seems unlikely for several reasons. J Comp Neurol 219: 384- 419. The information gained is used to identify the object and its properties, and to optimize its manipulation. However, such changes in the organization of adult cortex must be considered fundamentally different in nature from those in neonates where there is a critical period for plasticity Hubel and Wiesel, 1970; Wall, 1988.
Each protocol was split into five blocks to allow the subject a break. The short latency reflexes of 35 ± 1 ms mean ± s. In vision, if a moving grating is placed behind an aperture frame, the grating is perceived as sliding behind the aperture frame and its direction is perceived to be orthogonal to its orientation. The editorial commentaries concluding each section highlight the relevance of these phenomena for psycholinguistic and neuropsychological theory, and discuss similarities and apparent discrepancies in the findings reported in individual chapters. In the present study, when single square-wave gratings were presented through a circular aperture, subjects perceived the direction of motion to be orthogonal to the orientation of the gratings. All papers are peer reviewed and edited to the highest standards. Each stimulus was repeated five times in pseudorandom order.
The direction of motion of the components varied from 0° to 330° in steps of 30°. In all protocols except the barber pole, only probes within 5 mm of the center of the array were active; all other pins were retracted by 500 μm so that they did not contact the skin. The tactile stimuli were generated and delivered using a dense tactile array consisting of 400 independently controlled probes arrayed in a 20 × 20 matrix. The results highlight the portions of the reflex associated with the first spike of each burst with no effect from preceding afferent discharges. In Touch With The Future explores the science of touch, bringing together the latest findings from cognitive neuroscience about the processing of tactile information in humans. Exp Brain Res 70: 155- 165.
High-resolution functional magnetic resonance imaging of cortical activation during tactile exploration. Representation of reaching and grasping in the monkey postcentral gyrus. Whereas depth—context information can abolish the barber pole phenomenon visually , , , it does not tactually see. The commissural connexions of the somatic sensory cortex in the cat. Tactile sensibility in the human hand: receptive field characteristics of mechanoreceptive units in the glabrous skin area. Individual chapters address; the response of mechanoreceptors to stimuli including movement and shape , the role of the somatosensory cortex in processing tactile information, the psychophysics and neurophysiology of the detection and categorisation of somesthetic stimuli, perceptual constancy, recent findings in regard to short term and long term plasticity in the somatosensory cortex and the psychophysical correlates of this plasticity, and parallel versus serial information processing in the cortex. It provides us with the means to connect with our surroundings.
Secondary endings showed a poor dynamic sensitivity to passive stretch and a regular discharge. The density of the probes is greater than the innervation density on the fingertip, which leads to a smooth motion percept despite the inherent pixilation of the array. The responses of afferent fibres from the glabrous skin of the hand during voluntary finger movements in man. If approximately 20 ms is assumed to be the fastest spinally mediated reflex response from a cutaneous mechanoreceptor in the hand to an intrinsic hand muscle in a subject of average height , then, based on the conduction velocities above, the slowest spinally mediated latency could be 90-95 ms. The regular discharge rate of this afferent is highlighted in the raw neural signal and by the strong peaks in the autocorrelogram. The ambiguity of the stimulus motion was thus resolved in a way analogous to that observed when comparable stimuli are presented visually. Eur J Neurosci 11: 3983- 3994.
Am J Neuroradiol 20: 199- 205. The number of joint afferent recordings is insufficient to allow conclusions to be drawn. However, such synaptic coupling in hand muscles has not been examined. The average from only the last spike of each burst has an onset latency of 40. Exp Brain Res 39: 1- 9. Corpus callosum and the interhemispheric transmission of tactual learning.
The relation of corpus callosum connections to architectonic fields and body surface maps in sensorimotor cortex of new and old world monkeys. Functional organization of the somatosensory cortex in the primate A. Yet, the surface of the human body, the skin, is actually one huge sheet of tactile receptors. The perceived direction could be predicted from the strain profiles but not the indentation profiles see. The geometry of the aperture problem.
Temporal Dynamics of the Aperture Problem. That is, the senses interact to influence tactile perception in everything - from changing the feel of a surface or product by changing the sound it makes or the fragrance it has. The further functional subdivisions that occur within the first somatosensory area are given an anatom ical basis in the review by Edward Jones of connectivity in the primate sensory motor cortex. J Anat 103: 433- 455. This book is suitable for cognitive neuroscientists, cognitive psychologists, kinesthesiologists, and graduate courses in learning. Iwamura Y , Tanaka M. Intraneural microstimulation was used to guide penetration of a single cutaneous afferent.
Four receptors were located in the palm or webspace. On each trial, the aspect ratio and orientation of the aperture varied, as did the direction of movement of the grating relative to the orientation of the aperture. The dashed lines indicate the 99 % confidence interval and the dotted line highlights the short latency reflex response. The book encompasses levels of inquiry from ionic channels, single unit recordings of neural activity, and functional brain imaging of the coordinated activity of large neuronal ensembles to human psychophysics of controlled somatic stimulation. On each trial, the subject was presented with a stimulus consisting of two superimposed square-wave gratings moving in directions separated by 120°. Unlike their visual counterparts , however, the tactile barber poles yielded stable percepts. Here we investigate tactile motion processing using stimuli whose perceptual properties have been well established in vision research, namely superimposed gratings plaids , barber poles, and bar fields.
This behavior is identical to that observed in analogous visual psychophysical experiments. This volume draws together the increasing body of knowledge regarding the mechanisms underlying tactile sensation and how they relate to tactile perception. Autocorrelogram of the afferent discharge indicating a highly irregular discharge; inset, afferent spikes superimposed to confirm a single-unit recording. While the excitatory peak projecting above the 99 % confidence interval is not large, it was present at the same latency when averages were constructed from the first half of the recording only and from smaller numbers of triggers. Neural mechanisms of tactual form and texture perception.