NMDA RECEPTORS MEDIATE NEURONAL BURST FIRING IN RAT SOMATOSENSORY CORTEX INVIVO

Two patterns of neuronal firing, bursting and regular spiking, are obs erved in the somatosensory cortex of anesthetized rats. The effects of excitatory amino acid receptor agonists and antagonists on these disc harge types have been examined in vivo, in order to assess their invol vement in the generation of such firing patterns. The analysis of inte rspike interval histograms indicates that N-methyl-D-aspartate (NMDA) receptors are involved in the generation of bursting responses while n on-NMDA receptors mediate the regular spiking pattern of firing in ind ividual neurons. It is also suggested that a basal level of ongoing ne uronal excitation via the activation of non-NMDA receptors is required for bursting to be evoked through NMDA receptors.