Long-term motor cortical map changes following unilateral lesion of the hand representation in the motor cortex in macaque monkeys showing functional recovery of hand functions.

Purpose: How are motor maps modified within and in the immediate vicinity of a damaged zone in the motor cortex of non-human primates?

Methods: In eight adult macaque monkeys subjected to a restricted chemical lesion of the hand area in the primary motor cortex (M1), motor maps were established using intracortical micro-stimulation (ICMS) techniques. The monkeys were subdivided into five animals without treatment, whereas three monkeys received an anti-Nogo-A antibody treatment.

Results: Following permanent M1 injury, the lesion territory became largely non micro-excitable several months post-lesion, in spite of some recovery of hand function.

Influence of anti-Nogo-A antibody treatment on the reorganization of callosal connectivity of the premotor cortical areas following unilateral lesion of primary motor cortex (M1) in adult macaque monkeys.

Following unilateral lesion of the primary motor cortex, the reorganization of callosal projections from the intact hemisphere to the ipsilesional premotor cortex (PM) was investigated in 7 adult macaque monkeys, in absence of treatment (control; n = 4) or treated with function blocking antibodies against the neurite growth inhibitory protein Nogo-A (n = 3). After functional recovery, though incomplete, the tracer biotinylated dextran amine (BDA) was injected in the ipsilesional PM. Retrogradely labelled neurons were plotted in the intact hemisphere and their number was normalized with respect to the volume of the core of BDA injection sites.

Effects of unilateral motor cortex lesion on ipsilesional hand's reach and grasp performance in monkeys: relationship with recovery in the contralesional hand.

Manual dexterity, a prerogative of primates, is under the control of the corticospinal (CS) tract. Because 90-95% of CS axons decussate, it is assumed that this control is exerted essentially on the contralateral hand. Consistently, unilateral lesion of the hand representation in the motor cortex is followed by a complete loss of dexterity of the contralesional hand.