A local circuit neocortical synapse that operates via both NMDA and non-NMDA receptors

Abstract

1 In slices of rat neocortex, spike triggered averaging was employed to record in one neurone the excitatory postsynaptic potential (e.p.s.p.) generated by a spike in another, neighbouring neurone. When recorded at different membrane potentials, some of these e.p.s.ps exhibited a voltage relation typical of neuronal responses to N-methyl-D-aspartate (NMDA). 2 Selective NMDA antagonists reduced the amplitude of these e.p.s.ps, but had little effect on their early rising phase. In contrast, a less selective excitatory amino acid antagonist reduced all phases of the e.p.s.p. 3 By analyzing single axon e.p.s.ps we have been able to establish that the synaptic input to one cortical cell, delivered by a single presynaptic cortical cell, operates simultaneously via NMDA and non-NMDA amino acid receptors.