Segregazione e integrazione delle afferenze talamiche alle due suddivisioni citoarchiitettoniche dell'area motrice del Gatto

Cesari, Roberto ; Michelini, Sandro ; Spidalieri, Giuseppe ; Vedovato, Marta

Atti della Accademia nazionale dei Lincei. Rendiconti della Classe di scienze fisiche, matematiche e naturali, Série 8, Tome 65 (1978) no. 3-4, pp. 157-162

Résumé

Microelectrode recordings (glass micropipettes filled with 2.5 M KCl) from the two subdivisions of the motor cortex (area $4\gamma$ and $6\alpha\beta$, [5]) of chloralose-anaesthetized, curarized cats have been performed in order to characterize the response properties of the neurones receiving projections from the n. ventralis lateralis (VL). Extracellular unitary activity was obtained from 345 cells (226 from area 6 and 119 from area 4). Each one was tested for the effects of the electrical stimulation of the dorsal and ventral portions of VL (dVL and vVL). Only 3.1% of area 6 neurones and 3.3% of area 4 neurones were activated by dVL; 25.2% and 23.5% by vVL; 31.8% and 51.3% by stimulation of both. Response patterns were similar for units of the two areas and most latencies ranged between 1 and 8 msec. More detailed analysis of these data showed that the mean latencies of the responses to vVL-shocks were significantly longer in area 6 than in area 4. On the other hand, in area 4 the longest latencies were measured upon stimulation of dVL. These results, in comparison with anatomical studies showing that dVL sends projections mainly to area 6 and vVL mainly to area 4, suggest the possibility that the influence of dVL on area 4, as well as that of vVL on area 6, be exerted in part over cortico-cortical relays between the two subdivisions of motor cortex.