 |
 Previous Article | Next Article 
Journal of Neuroscience, Vol 7, 1672-1681, Copyright © 1987 by Society for Neuroscience
Tactile discrimination of shape: responses of rapidly adapting mechanoreceptive afferents to a step stroked across the monkey fingerpad
RH LaMotte and MA Srinivasan
Responses of rapidly adapting Meissner corpuscle mechanoreceptive afferent
fibers (RAs) to steps of varying shape stroked across the distal fingerpad
were recorded from anesthetized monkeys. A series of flat plates were used,
each having an increase in thickness (a step) in the middle so that
one-half of the plate was thicker than the other. The cross-sectional shape
of the step approximated that of a half-cycle sinusoid, 0.5 mm high. The
width (half-cycle wavelength) of the sinusoidal step was varied from 0 to
3.13 mm, producing a series of step shapes that differed in steepness and
curvature. These steps could be broadly categorized into 2 groups, "steep"
and "gradual." Each step was stroked back and forth under constant
compressional force, using a servocontrolled mechanical stimulator. The
RA's response to a step provided a spatial pattern of action potentials in
which the occurrence of each impulse corresponded to a position of the step
on the skin. This response consisted of a single "burst" of impulses to the
sinusoidal portion of the step. Changes in stroke direction, step shape, or
velocity of stroking primarily affected the RA discharge rate during the
burst, and, less consistently, the spatial width of the burst. For a given
step shape and stroke velocity, the discharge rate was greater for strokes
from the low to the high side of the step than for strokes from the high to
the low side. Discharge rate was greater for steep than for gradual steps
and, for a given step, it increased with stroke velocity. All the major
features of the responses were interpreted as being due predominantly to
the sensitivity of the RA to vertical velocity at the most sensitive spot
on its receptive field, together with a sensitivity to the rate of change
in skin curvature at that spot. RA discharge rate distinguished not only
the gross differences between steep and gradual steps, but also some of the
finer differences in sharpness among steep steps. From a comparison with
the human capacity for tactile discrimination of the steps, it was
concluded that RAs, through their discharge rates, provide primarily
"intensive" information about the sharpness of shapes.
This article has been cited by other articles:
|
|
|
|
 
A. Depeault, E.-M. Meftah, and C. E. Chapman
Tactile Speed Scaling: Contributions of Time and Space
J Neurophysiol,
March 1, 2008;
99(3):
1422 - 1434.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
S. J. Bensmaia, P. V. Denchev, J. F. Dammann III, J. C. Craig, and S. S. Hsiao
The Representation of Stimulus Orientation in the Early Stages of Somatosensory Processing
J. Neurosci.,
January 16, 2008;
28(3):
776 - 786.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
R. M. Friedman, P. S. Khalsa, K. W. Greenquist, and R. H. LaMotte
Neural Coding of the Location and Direction of a Moving Object by a Spatially Distributed Population of Mechanoreceptors
J. Neurosci.,
November 1, 2002;
22(21):
9556 - 9566.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
J. W. Bisley, A. W. Goodwin, and H. E. Wheat
Slowly Adapting Type I Afferents From the Sides and End of the Finger Respond to Stimuli on the Center of the Fingerpad
J Neurophysiol,
July 1, 2000;
84(1):
57 - 64.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
A. W. Goodwin and H. E. Wheat
Effects of Nonuniform Fiber Sensitivity, Innervation Geometry, and Noise on Information Relayed by a Population of Slowly Adapting Type I Primary Afferents from the Fingerpad
J. Neurosci.,
September 15, 1999;
19(18):
8057 - 8070.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
F. Vega-Bermudez and K. O. Johnson
Surround Suppression in the Responses of Primate SA1 and RA Mechanoreceptive Afferents Mapped with a Probe Array
J Neurophysiol,
June 1, 1999;
81(6):
2711 - 2719.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
R. H. Lamotte, R. M. Friedman, C. Lu, P. S. Khalsa, and M. A. Srinivasan
Raised Object on a Planar Surface Stroked Across the Fingerpad: Responses of Cutaneous Mechanoreceptors to Shape and Orientation
J Neurophysiol,
November 1, 1998;
80(5):
2446 - 2466.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
P. Jenmalm, A. W. Goodwin, and R. S. Johansson
Control of Grasp Stability When Humans Lift Objects With Different Surface Curvatures
J Neurophysiol,
April 1, 1998;
79(4):
1643 - 1652.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
M. J. Dodson, A. W. Goodwin, A. S. Browning, and H. M. Gehring
Peripheral Neural Mechanisms Determining the Orientation of Cylinders Grasped by the Digits
J. Neurosci.,
January 1, 1998;
18(1):
521 - 530.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
A. W. Goodwin, V. G. Macefield, and J. W. Bisley
Encoding of Object Curvature by Tactile Afferents From Human Fingers
J Neurophysiol,
December 1, 1997;
78(6):
2881 - 2888.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
D. T. Blake, K. O. Johnson, and S. S. Hsiao
Monkey Cutaneous SAI and RA Responses to Raised and Depressed Scanned Patterns: Effects of Width, Height, Orientation, and a Raised Surround
J Neurophysiol,
November 1, 1997;
78(5):
2503 - 2517.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
