Affiliations: Department of Psychology, Vanderbilt University,
Nashville, TN, USA
Note: [] Corresponding author: Jon H. Kaas, Vanderbilt University, 301
Wilson Hall, 111 21st Avenue South, Nashville, TN 37203, USA. Tel.: +1 615 322
6029; Fax: +1 615 343 8449; E-mail: [email protected]
Abstract: As a result of an extensive search, we were able to obtain a limited
number of macaque monkeys, New World squirrel monkeys, and prosimian galagos
years after they had received a therapeutic amputation of a forelimb or
hindlimb as a treatment for injury. Forelimb or hindlimb regions of primary
motor cortex, M1, were stimulated in these primates with microelectrodes using
amounts of current just sufficient to evoke a movement. Results were compared
to those obtained from normal primates or from M1 contralateral to the intact
limb in the same primates. In all cases, more sites in M1 contralateral to the
amputated limb evoked movements of the limb stump and muscle in the adjoining
shoulder or hip. In two of the macaque monkeys, injections in M1 reveal more
widespread intrinsic connections than in normal M1, and in several monkeys and
galagos, injections of tracers in muscles of the stump, shoulder, or hip
labeled spinal cord motor neurons that normally project to the distal limb.
These anatomical results suggest that the functional changes in M1 following
amputation are mediated in part by the formation of new connections.
