Aims: 

Oscillatory activity has been observed in the basolateral amygdala (BLA) in vivo during emotional arousal and is thought to have an important role in emotional processing. GABAergic interneurons are known to have a critical role in the generation and maintenance of network oscillations. Using an in vitro model of gamma oscillations in the BLA, we have investigated the role of GABAergic inhibition in this activity.

Methods: 

Oscillations were induced in coronal slices (450mm) of rat BLA from male Wistar rats by bath application of kainic acid (400nM). Compounds known to affect GABA_A receptor-mediated inhibition; Gabazine (1mM), Pentobarbital (30mM) and Diazepam (1mM), were applied to stable, persistent oscillations.

Results: 

Intracellular recordings during oscillations revealed that principal cells in the BLA receive gamma frequency IPSPs in phase with the field oscillation. Blockade of GABA_A receptors by Gabazine completely abolished the oscillatory activity. Pentobarbital significantly reduced the frequency but not the power of the oscillation (control v. Pentobarbital; frequency 32 ± 2 v. 26 ± 1 Hz, P=<0.05; power 23 ± 9 v. 2 ± 1 mV²/Hz, P > 0.05, n = 5). Diazepam had no significant effect on the frequency or power of the oscillation (control v. Diazepam; frequency 34 ± 1 v. 33 ± 1 Hz, P > 0.05; power 135 ± 84 v. 96 ± 73 mV²/Hz, P > 0.05, n = 5).

Conclusion: 

BLA oscillations are subject to modulation at the barbiturate site on GABA_A receptors but not the benzodiazepine site. These results demonstrate that GABA_A receptor-mediated inhibition is important in network oscillations in the BLA.