Induction of synchronous oscillatory activity in the rat lateral amygdala in vitro is dependent on gap junction activity.

Synchronized and rhythmic activity within the amygdala is thought to play a pivotal role in the generation of fear- and anxiety-related behaviour. The aim here was to determine the validity of the in vitro amygdala slice preparation to investigate the generation of rhythmic activity similar to that observed in vivo. Extracellular population activity recorded from the lateral nucleus of the amygdala in vitro showed significant enhancement of activity within the theta-band frequency (3-9 Hz) in the presence of kainic acid (100 nm; n=18). Alterations in the patterns of oscillatory activity within the gamma frequency band (20-40 Hz) were observed in the presence of (RS)-3,5-dihydroxyphenylglycine (10 microm; n=7) or carbachol (50 microm; n=5). Theta frequency oscillatory activity was blocked in the presence of the gap junction blocker carbenoxolone (100 mm), whereas gamma frequency oscillatory activity showed increased variability in the dominant frequency of rhythmic activity. The results suggest that the neuronal circuitry of the amygdala in vitro is capable of generating and sustaining rhythmic activity and that intercellular communication via gap junctions may play a role in the synchronization of population activity underlying this oscillatory activity.