Modeling Dynamic Receptive Eld Changes Produced by Intracortical Microstimulation

Intracortical microstimulation (ICMS) of a localized site in the somatosensory cortex of rats and monkeys for 2{6 hours produces a large increase in the cortical representation of the skin region represented by the ICMS-site neurons before ICMS, with very little eeect on the ICMS-site neuron's RF location, RF size, and responsiveness (Recanzone et al., 1992). The \EXIN" (aaerent excitatory and lateral inhibitory) learning rules (Marshall, 1995) are used to model RF changes during ICMS. The EXIN model produces reorganization of RF topography similar to that observed experimentally. The possible role of inhibitory learning in producing the eeects of ICMS is studied by simulating the EXIN model with only lateral inhibitory learning. The model also produces an increase in the cortical representation of the skin region represented by the ICMS-site RF. ICMS is compared to artiicial scotoma conditioning (Pettet & Gilbert, 1992) and retinal lesions (Darian-Smith & Gilbert, 1995), and it is suggested that lateral inhibitory learning may be a general principle of cortical plasticity.