Journal of Neurophysiology, Vol 38, Issue 1 19-25, Copyright © 1975 by APS
Parametric studies of dorsal horn neurons responding to tactile stimulation
P. B. Brown, J. L. Fuchs and D. N. Tapper
Dorsal horn neurons responding to tactile input were recorded in segments
L3-S2 of unanesthetized, low-spinal cats. Single units were characterized
with regard to receptive field (RF) location, RF size and shape,
spontaneous discharge rate, central delay, and convergence of four tactile
afferent types. 1. RF size increased from the toes to the calf region. 2.
Length-width ratio increased from the toes to the calf and declined from
the calf to the hip. 3. The relation between RF size and position on the
limb was independent of segmental and laminar location of the neurons. 4.
RF size was positively correlated with spontaneous discharge rate. 5. The
relation between RF size and shape and RF position can be interpreted in
terms of regional variations in the magnitude of the gradient of
representation in the dorsal horn somatotopic map. 6. Central delay was
negatively correlated with both RF size and rate of ongoing discharge. 7.
There were no statistically significant differences among the laminae with
respect to central delay, RF size or shape, ongoing discharge, or
convergence combinations of the four tactile afferent systems. 8. Data
presented were at variance with Wall's laminar cascading model for laminae
IV-VI. Our results suggest that the model should be modified, at least to
emphasize monosynaptic tactile input to all three of these laminae.
