UNILATERAL LESIONS OF THE FORELIMB AREA OF RAT MOTOR CORTEX - LACK OFEVIDENCE FOR USE-DEPENDENT NEURAL GROWTH IN THE UNDAMAGED HEMISPHERE

Unilateral lesions of the forelimb area of the motor cortex have been reported to produce enhanced dendritic outgrowth in the undamaged hemi sphere in response to the behavioral asymmetry produced by the lesions (e.g. Jones, T.A. and Schallert, T., Use-dependent growth of pyramida l neurons after neocortical damage, J. Neurosci., 14 (1994) 2140-2152) . We attempted to replicate this result and to determine if there were sex differences in cortical plasticity using the Jones and Schallert model. Animals were given either unilateral aspiration or electrolytic lesions of the forelimb area of the motor cortex or a sham operation. Use of the forelimb ipsilateral to the lesion for postural support wa s assessed pre- and postsurgery. Eighteen days after surgery the anima ls were sacrificed and the brains processed for Golgi-Cox staining or a series of other stains for acetylcholine, astrocytes (glial fibrilla ry acidic protein), and microglia (OX-42). Although the lesions produc ed significant behavioral asymmetry and enhanced glial response on the lesioned side, there was little evidence for use-dependent neural gro wth in the undamaged hemisphere in either sex.