A single stimulus applied to the endopyriform nucleus evoked in 35 of the 101 basolateral amygdaloid (BLA) neurons a slow excitatory postsynaptic potential (s‐EPSP) of varying latencies. The s‐EPSP could be graded by changing the stimulus intensity and, on reaching the threshold, triggered action potentials. At stimulus intensity just subthreshold for evoking a spike, the s‐EPSP has an average amplitude of 16.3 ± 1.4 mV, a time to peak of 25.7 ± 3.8 ms, and a duration of 124 ± 14 ms. The s‐EPSP was reversibly blocked by DL‐2‐amino‐5‐phosphonovaleate (DLAPV) or ketamine, indicating its mediation through N‐methyl‐D‐aspartate (NMDA) receptor activation. However, the s‐EPSP was not able to follow stimulus frequency of 1 Hz, suggesting that APV‐sensitive s‐EPSP is probably generated by a polysynaptic pathway. The s‐EPSP was greatly enhanced by synaptic stimulation in the presence of bicuculline or in Mg++‐free solution leading to the genesis of paroxysmal depolarizing shift (PDS). The s‐EPSP can undergo robust long‐term potentiation (LTP) following tetanic stimulation. These results suggest that the NMDA receptor‐mediated s‐EPSP may play an important role in epileptogenesis and synaptic plasticity in the amygdala. © 1993 Wiley‐Liss, Inc.
All Science Journal Classification (ASJC) codes
- Cellular and Molecular Neuroscience