QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

HOME  |   SEARCH  |   ARCHIVE  |   SUBSCRIBE  |   CONTACT  |   HELP

This Article Full Text Full Text (PDF) Submit an eLetter Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Wheat, H. E. Articles by Goodwin, A. W. Search for Related Content PubMed PubMed Citation Articles by Wheat, H. E. Articles by Goodwin, A. W.

 Previous Article  |  Next Article 

The Journal of Neuroscience, October 1, 2001, 21(19):7751-7763

Tactile Discrimination of Edge Shape: Limits on Spatial Resolution Imposed by Parameters of the Peripheral Neural Population

Heather E. Wheat and Antony W. Goodwin

Department of Anatomy and Cell Biology, University of Melbourne, Victoria 3010, Australia

When the flat faces of a coin are grasped between thumb and index finger, a "curved edge" is felt. Analogous curved edges were generated by our stimuli, which comprised the flat face of segments of annuli applied passively to immobilized fingers. Humans could scale the curvature of the annulus and could discriminate changes in curvature of ~20 m¹. The responses of single slowly adapting type I afferents (SAIs) recorded in anesthetized monkeys could be quantified by the product of two factors: their sensitivity and a spatial profile dependent only on the radius of the annulus. This allowed us to reconstruct realistic SAI population responses that included noise, variation in fiber sensitivity, and varying innervation patterns. The critical question was how relatively small populations (~70 active fibers) can encode edge curvature with such precision. A template-matching approach was used to establish the accuracy of edge representation in the population. The known large interfiber variability in sensitivity had no effect on curvature resolution. Neural resolution was superior to human performance until large levels of central noise were present showing that, unlike simple detection, spatial processing is limited centrally. In contrast to the behavior of mean response codes, neural resolution improved with increasing covariance in noise. Surprisingly, resolution for any single population varied considerably with small changes in the position of the stimulus relative to the SAI matrix. Overall innervation density was not as critical as the spacing of receptive fields at right angles to the edge.

Key words: tactile resolution; mechanoreceptive afferents; somatosensory; form processing; spatial coding; innervation density; curvature; edges

---

Copyright © 2001 Society for Neuroscience  0270-6474/01/21197751-13$05.00/0

This article has been cited by other articles:

				P. H. Thakur, P. J. Fitzgerald, J. W. Lane, and S. S. Hsiao Receptive Field Properties of the Macaque Second Somatosensory Cortex: Nonlinear Mechanisms Underlying the Representation of Orientation Within a Finger Pad J. Neurosci., December 27, 2006; 26(52): 13567 - 13575. [Abstract] [Full Text] [PDF]

				S. C. Leiser and K. A. Moxon Relationship Between Physiological Response Type (RA and SA) and Vibrissal Receptive Field of Neurons Within the Rat Trigeminal Ganglion J Neurophysiol, May 1, 2006; 95(5): 3129 - 3145. [Abstract] [Full Text] [PDF]

				H. E. Wheat, L. M. Salo, and A. W. Goodwin Human Ability to Scale and Discriminate Forces Typical of Those Occurring during Grasp and Manipulation J. Neurosci., March 31, 2004; 24(13): 3394 - 3401. [Abstract] [Full Text] [PDF]

Home  |   Search  |   Archive  |   Subscribe  |   Contact  |   Help