ELECTROPHYSIOLOGICAL STUDY OF THE CONNECTION BETWEEN MEDIAL THALAMUS AND ANTERIOR CINGULATE CORTEX IN THE RAT

We characterized the neuronal properties of the anterior cingulate cor tex (ACC) evoked by electrical stimulation of the medial thalamus (MT) . MT stimulation sites were found by their neuronal responses to noxio us stimuli. Of 487 units identified histologically in the rat ACC, 94% were activated trans-synaptically at different areas of the ACC. Six percent of MT-evoked ACC units were activated antidromically and all o f these units projected to a specific nucleus of MT. We suggest that M T nuclei mediate different aspects of nociceptive information to speci fic ACC areas, and that nociceptive information in the MT is modulated reciprocally by activities from the ACC.