Spike doublets in neurons of the lateral amygdala: Mechanisms and contribution to rhythmic activity

A majority of projection neurons in the lateral amygdala generate oscillato ry spike firing in the theta-frequency range, largely due to intrinsic memb rane properties. Here we report on the occurrence of spike doublets in abou t 70% of these cells. Spike doublets consisted of a fast initial and a seco nd slower component, which were mediated by sodium- and calcium-dependent m echanisms, respectively. With increased level of depolarization, there was a gradual transition of fast action potentials, regular alternation of fast action potentials and spike doublets, regular spike doublets, and high-thr eshold oscillations. Fast Fourier transforms demonstrated the rhythmic natu re of spike doublers at around 3 Hz with an intra-doublet frequency of 25-8 0 Hz. Spike doublets may thus contribute to the overall rhythmicity in the membrane potential patterns of projection cells and support the integration of synaptic input signals. NeuroReport 11:1703-1708 (C) 2000 Lippincott Wi lliams & Wilkins.