MOTOR AND SOMATOSENSORY CORTICOSTRIATAL PROJECTION MAGNIFICATIONS IN THE
SQUIRREL MONKEY.
Flaherty, Alice W., Ann M. Graybiel.
Massachusetts General Hospital, Department of Neurology, Boston,
Massachusetts 02114, U.S.A., Massachusetts Institute of Technology, Department
of Brain and Cognitive Sciences, Cambridge, Massachusetts 02139, U.S.A..
APStracts 2:0257N, 1995.
SUMMARY AND CONCLUSIONS
1. Motor and somatosensory cortex project massively to the primate striatal
matrix, terminating in distributed sets of overlapping projection zones
(matrisomes) within the putamen. To study this system quantitatively, we have
developed a computer-assisted estimation of the changes in magnification that
occur as motor and somatosensory cortical body representations are projected
onto the putamen. 2. Cortical and striatal body maps were assessed in squirrel
monkeys by injecting anterograde tract tracers into electrophysiologically
identified body-part representations in cortical areas 4, 3a, 3b, and 1.
Relative projection magnification was defined as the ratio of the cortical
injection site volume to the striatal projection site volume. 3. Magnification
comparisons indicate that the tracers WGA-HRP (wheatgerm agglutinin-conjugated
horseradish peroxidase) and 35 S-methionine have similar sensitivities. 4. The
relative proportions of body-part representations in the striatal maps were
not significantly different from those in cortical maps. Both had large
representations of hand, foot, and mouth, and smaller representations of
trunk. 5. The relative magnification of the motor cortex projection to the
striatum was roughly twice as large as those of projections from individual
somatosensory areas. 6. These findings suggest that in the sensorimotor
striatum, motor and somatosensory inputs may undergo different proportions of
local processing at the borders of their distribution zones (striosomes and
matrisomes).
Received 23 December 1994; accepted in final form 17 July 1995.
APS Manuscript Number J805-4.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 24 August 1995.