The transition between the sub-band gamma oscillations represents a change of signal transmission and receiving state in the basolateral amygdala.

Abstract

The Basolateral nucleus of the amygdala (BLA) is known to play an important role in regulating the emotional states (i.e. fear, anxiety) and various gamma-band oscillations (GBOs) appearing in each of these states. Furthermore, the prefrontal cortex (PFC) and BLA have a strong bidirectional connection supports this role. However, significance of GBOs in signal process in the BLA is not yet known. Here, we propose that distinct gamma-band oscillations represent distinct signal transmission and receiving state of the BLA which is determined by the ratio of excitatory and inhibitory gain from PFC to BLA. To examine this, we constructed the bidirectional network model between the PFC and BLA with spiking neuron models and the local field potential (LFP) used to measure transient GBOs of models. We found that this connection makes two different GBOs (i.e. 25 ？ 35 Hz and 50 ？ 60 Hz) in the BLA. Moreover, state transition could occur from one GBO to the other in the BLA by modulating excitatory and inhibitory gain ratio from the PFC to BL. Specifically, with excitation and inhibition gains balanced, signal transmission from the PFC to BLA was reduced. After which intrinsic BLA gamma-band synchrony routes signals to the PFC. On the other hand, by increasing the excitatory gains, the transient synchronized oscillation in the PFC makes BLA synchronize with another GBO. In sum, our findings suggest that distinct GBOs in the BLA show communication direction of the BLA which can be controlled by gain ratio of the PFC to BLA.