LARGE-SCALE SPROUTING OF CORTICAL CONNECTIONS AFTER PERIPHERAL INJURYIN ADULT MACAQUE MONKEYS

Distributions of thalamic and cortical connections were investigated i n four macaque monkeys with long-standing, accidental trauma to a fore limb, to determine whether the growth of new connections plays a role in the reorganization. of somatosensory cortex that occurs after major alterations in peripheral somatosensory inputs, In each monkey, micro electrode recordings of cortical areas 3b and 1 demonstrated massive r eorganizations of the cortex related to the affected limb. injections of tracers in area 1 of these monkeys revealed normal patterns of thal amocortical connections, but markedly expanded lateral connections in areas 3b and 1. Thus, the growth of intracortical but not thalamocorti cal connections could account for much of the reorganization of the se nsory maps in cortex.