PhD Scientific Days 2023

Neurosciences - Posters H

Regulation of Contextual Fear Learning by Prelimbic Cortex-Projecting Anterior Basal Amygdala Neurons

Text of the abstract

Introduction:
The basolateral amygdala (BLA) has been implicated in aversive and reward-related behaviors. However, the microcircuit-level mechanism by which the BLA mediates these opposing motivational states remains unknown. Recent anatomical studies have suggested morphological heterogeneity of the basal amygdala (BA) along its antero-posterior axis. Here, we aimed to investigate the role of BA neurons projecting to the prelimbic cortex (PL) in contextual fear learning.

Aims:
To identify a genetic marker for the anterior BA region, investigate the role of arhgef-6+ BA neurons in anxiety and risk assessment behaviors, and assess their contribution to contextual and cued fear learning. Further, to study the feedback projections from the BA to the PL.

Methods:
We used arhgef6-cre mice and viral-based tracing to selectively target arhgef-6+ BA neurons projecting to the PL and assess their function. We employed the elevated plus maze test to evaluate anxiety and risk assessment behaviors and conditioned fear learning paradigms to assess contextual and cued fear learning.

Results:
We identified the arhgef-6 protein as a genetic marker for the anterior BA region. Inhibiting neurotransmission of arhgef6+ BA neurons reduced risk assessment behavior and impaired contextual and cued fear learning. Viral-based tracing revealed that these neurons densely innervate the PL and dorsomedial striatum (DSM) regions. Selective inhibition of PL-projecting anterior BA neurons impaired contextual fear recall but had no effect on cued fear expression.

Conclusion:
Our study suggests that anterior BA neurons and their projection to the PL play a crucial role in regulating contextual fear learning. These findings provide new insights into the microcircuit-level mechanisms of the BLA and shed light on the neural circuits underlying fear-related behaviors.

Funding:
This work was supported by the Hungarian Brain Research Program 2017-1.2.1-NKP-2017-00002 to N.H., New National Excellence Program of the Ministry for Innovation and Technology (ÚNKP-22-4-I-SE-5) to B.B., and by the Sapientia Hungariae Foundation Collegium Talentum Scholarship to Zs.R.