Periodic Reporting for period 2 - ventralHippocampus (Neuronal circuits for emotions in the ventral CA1 hippocampus)
Reporting period: 2018-07-01 to 2019-12-31
Pyramidal cells of the CA1 region of the hippocampus represent a main hippocampal output to numerous brains regions relevant for emotional and cognitive processes. The activity and timing of these CA1 pyramidal cells are controlled by a set of very diverse long-range afferent inputs and by local GABAergic interneurons. However, the function of afferent pathways to- and of local GABAergic interneurons in the ventral CA1 hippocampus during contextual fear conditioning and anxiety behaviours have not been investigated so far. We hypothesise that distinct sub-circuits in the ventral CA1 hippocampus differentially contribute to emotional behaviours by diverse and complementary neuronal and network mechanisms.
To test this hypothesis, we are using an innovative cross-level approach combining single-unit recordings and calcium imaging of ventral CA1 GABAergic interneurons and of afferent brain regions to the ventral CA1 hippocampus, selective optogenetic strategies, cell-type-specific viral tracing, juxtacellular recording and labelling from ventral CA1 GABAergic interneurons, and behavioural paradigms in rodents. The proposal is capitalizing on identifying specific neuronal circuits and mechanisms in the ventral CA1 hippocampus to understand how normal and pathological fear and anxiety might arise at the behavioural level. Altogether, we aim to discover logics of cortical computations during emotional behaviour which may lead to translational applications for fear and anxiety disorders in humans.
Neural representations of emotions are ultimately supported by distinct neuronal cell-types interacting together by selective synaptic contacts and neural activity patterns. We hypothesize that distinct emotional paradigms are implemented by the selective recruitment of micro- and large-scale neural circuits of the ventral CA1 hippocampus. The results of our experimental approaches will determine how information is computed within hippocampal circuit motifs to mediate the emergence and the formation of emotional memories.