MECHANISMS CONTROLLING NEURONAL PLASTICITY IN SOMATOSENSORY CORTEX

gamma-Aminobutyric acid containing neurons in the somatosensory cortex are the major controlling element determining receptive field size an d location. This control of the excitability of cortical neurons can b e modulated by activity arising in the basal forebrain. A hypothesis i s developed stating that both cholinergic and gamma-aminobutyric acid containing projections from the basal forebrain play important roles i n the production of a state in cortex permitting neuronal plasticity t o occur. This proposed mechanism involving a simultaneous reduction of inhibition and increased release of acetylcholine allows sensory sign als to induce long-term changes in the location and responsiveness of cutaneous receptive fields, thereby changing the somatotopic organizat ion of primary somatosensory cortex.