NMDA receptors mediate neuronal burst firing in rat somatosensory cortex in vivo.

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