Growth of new brainstem connections in adult monkeys with massive sensory loss

Growth of new brainstem connections in adult monkeys with massive sensory loss

Department of Psychology, Vanderbilt University, Nashville, TN 37240

Edited by Charles G. Gross, Princeton University, Princeton, NJ, and approved March 7, 2000 (received for review December 28, 1999)

Abstract

Somatotopic maps in the cortex and the thalamus of adult monkeys and humans reorganize in response to altered inputs. After loss of the sensory afferents from the forelimb in monkeys because of transection of the dorsal columns of the spinal cord, therapeutic amputation of an arm or transection of the dorsal roots of the peripheral nerves, the deprived portions of the hand and arm representations in primary somatosensory cortex (area 3b), become responsive to inputs from the face and any remaining afferents from the arm. Cortical and subcortical mechanisms that underlie this reorganization are uncertain and appear to be manifold. Here we show that the face afferents from the trigeminal nucleus of the brainstem sprout and grow into the cuneate nucleus in adult monkeys after lesions of the dorsal columns of the spinal cord or therapeutic amputation of an arm. This growth may underlie the large-scale expansion of the face representation into the hand region of somatosensory cortex that follows such deafferentations.

Footnotes

↵ * To whom reprint requests should be addressed. E-mail: neeraj.jain{at}vanderbilt.edu.
This paper was submitted directly (Track II) to the PNAS office.
Article published online before print: Proc. Natl. Acad. Sci. USA, 10.1073/pnas.090572597.
Article and publication date are at www.pnas.org/cgi/doi/10.1073/pnas.090572597
Abbreviations:

HRP,

horseradish peroxidase;

CNS,

central nervous system