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Thesis Defense

Author: Seyma Nayir Jordan
Title: How does cardiac tissue strain influence spontaneous electrical activity and beating variability?
Location: Seminarraum
Wed 5. April 2023 14:00

Thesis Defense

Author: Konstantinos Koukoutselos
Title: Anticipatory coding of anxiety in the ventral hippocampus
Location: Seminarraum
Thu 6. April 2023 10:00
Abstract Anxiety is an aversive emotional state reflecting the expectation of potential threats. The ventral hippocampus (vHip) is a key brain region for the genesis of anxiety responses. Recent studies have shown that anxiety is mediated by the recruitment of pyramidal neurons from the vHip (anxiety neurons) targeting various limbic structures. Despite the function of the vHip in triggering emotional responses, whether the vHip also signals the anticipation of an anxiogenic experience remains elusive. To address this question, we developed a novel trial- based rodent anxiety behavioural task called the forced emotional-shifting task (FEST), with separate temporal and spatial contexts for the anxiogenic experience and its anticipation. By performing in vivo single-unit recordings from the vHip of freely moving mice, we identified both anxiety neurons as well as a distinct neuronal population with ramping activity in the safe compartment of the forced emotional-shifting task, suggestive of an anticipatory coding for anxiety. The activity of these anticipatory neurons intrinsically depended on the experience of anxiety, indicating that anticipatory neurons are not the mere result of novelty or time processing. Moreover, unpredictable time intervals impaired the formation of anticipatory neurons, while long structured time intervals enhanced their response. The activity of anxiety neurons correlated with the magnitude of the anticipatory signal. Optogenetic silencing of the vHip activity in the safe compartment led to lower anxiety- related neuronal activity, indicating a possible functional interaction between anticipatory and anxiety neurons. Collectively, our results suggest that anxiety processing comprises different stages, with distinct neuronal populations within the vHip mediating anxiety or its anticipation.