Cortical responses to impulses from single Pacinian corpuscles in the cat's hind limb

Abstract

Individual Pacinian corpuscles situated near the cat's crural interosseous membrane were exposed and stimulated with weak mechanical pulses delivered by a piezo-electric transducer element, impulses so initiated being monitored in the interosseous nerve. With the nerve intact, single impulses were found to be capable of evoking in contralateral area II small predominantly surface-positive cortical potentials, usually less than 40 μV in amplitude. In some instances, use of an averaging computer was necessary to reveal their presence. When two impulses from the same or from different corpuscles were set up at various time intervals, summation or occasionally facilitation of cortical response occurred at short intervals followed by depression persisting for several hundred msec: single impulses also depressed the response to subsequent electrical stimulation of the nerve. These observations confirm the great security of transmission at synapses interposed on pathways to cortex, and demonstrate the occurrence of considerable spatial and temporal spread of action from the single active input fibre.