Reversible relocation of representational boundaries of adult rats by intracortical microstimulation

Cortical reorganization of somatosensory maps of adult rats is not restricted to central, already cutaneous zones. A few hours of intracortical microstimulation (ICMS) at the boundaries of the hindpaw representation generated plastic reorganization beyond these functionally defined representational borders by inducing new skin field representations in previously non-somatic cortical regions, from where low-threshold movements could be elicited. In this way, individually defined borders could be reversibly relocated over distances up to 800 microns, containing selectively skin field representations of the ICMS site. Response amplitude and latency characteristics of these newly induced cutaneous recordings sites resembled those recorded under control in the central representational zones. The results suggest that ICMS-induced plasticity acts across areal and modality borders by fast modulation of synapses in overlapping cortical and subcortical networks.