Krabbe, S. | Search bioRxiv

bioRxiv2018

Adaptive disinhibitory gating by VIP interneurons permits associative learning

Learning drives behavioral adaptations necessary for survival. While plasticity of excitatory projection neurons during associative learning is studied extensively, little is known about the contributions of local interneurons. Using fear conditioning as a model for associative learning, we find that behaviorally relevant, salient stimuli cause learning by tapping into a local microcircuit consisting of precisely connected subtypes of inhibitory interneurons. By employing calcium imaging and optogenetics, we demonstrate that vasoactive intestinal peptide (VIP)-expressing interneurons in the basolateral amygdala are activated by aversive events and provide an instructive disinhibitory signal for associative learning. Notably, VIP interneuron responses are plastic and shift from the instructive to the predictive cue upon memory formation. We describe a novel form of adaptive disinhibitory gating by VIP interneurons that allows to discriminate unexpected, important from irrelevant information, and might be a general dynamic circuit motif to trigger stimulus-specific learning, thereby ensuring appropriate behavioral adaptations to salient events.

neuroscience↗

bioRxiv2018

Amygdala neuronal ensembles dynamically encode behavioral states

Internal states, including affective or homeostatic states, are important behavioral motivators. The amygdala is a key brain region involved in the regulation of motivated behaviors, yet how distinct internal states are represented in amygdala circuits is unknown. Here, by imaging somatic neural calcium dynamics in freely moving mice, we identify changes in the relative activity levels of two major, non-overlapping populations of principal neurons in the basal nucleus of the amygdala (BA) that predict switches between exploratory and non-exploratory (defensive, anxiety-like) behavioral states across different environments. Moreover, the amygdala widely broadcasts internal state information via several output pathways to larger brain networks, and sensory responses in BA occur independently of behavioral state encoding. Thus, the brain processes external stimuli and internal states in an orthogonal manner, which may facilitate rapid and flexible selection of appropriate, state-dependent behavioral responses.

neuroscience↗