TY - JOUR T1 - Variable interhemispheric asymmetry in layer V of the supplementary motor area following cervical hemisection in adult macaque monkeys JF - eneuro JO - eNeuro DO - 10.1523/ENEURO.0280-20.2020 SP - ENEURO.0280-20.2020 AU - A. Contestabile AU - R. Colangiulo AU - M. Lucchini AU - E. M. Rouiller AU - E. Schmidlin Y1 - 2020/09/11 UR - http://www.eneuro.org/content/early/2020/09/11/ENEURO.0280-20.2020.abstract N2 - Motor cortical areas from both hemispheres play a role during functional recovery after a unilateral spinal cord injury (SCI). However, little is known about the morphological and phenotypical differences that a SCI could trigger in corticospinal neurons of the ipsilesional and contralesional hemisphere. Using an SMI-32 antibody which specifically labeled pyramidal neurons in cortical layers V, we investigated the impact of a unilateral cervical cord lesion on the rostral part (F6) and caudal part (F3) of the supplementary motor area (SMA) in both hemispheres of eight adult macaque monkeys compared with four intact control monkeys. We observed in F3 (but not in F6) interindividual variable and adaptive interhemispheric asymmetries of SMI-32 positive layer V neuronal density and dendritic arborization, which are strongly correlated with the extent of the SCI as well as the duration of functional recovery, but not with the extent (percentage) of functional recovery.Significance statement1. This study consists in a precise quantification on two different levels of the histological consequences on the long term of a traumatic and sudden unilateral interruption of the corticospinal tract at cervical level in 8 non-human primates (adult macaque monkeys).2. The lesion affected the density and the morphology of layer v pyramidal neurons in the supplementary motor area (SMA), in the form of an interhemispheric adaptive asymmetry, correlated to the lesion size and duration of functional recovery.3. These changes are reminiscent of those observed in SMA after unilateral lesion of the primary motor cortex, suggesting to some extent comparable mechanism of functional motor recovery from unilateral cortical or spinal lesion.4. The dendritic arborization in the basal dendrites of the SMI-32 positive neurons in layer V showed a more prominent interhemispheric effect of the lesion than the apical dendrites. ER -