ALTERED HIPPOCAMPAL CRITICALITY IN A DEPRESSION-LIKE MOUSE MODEL

Major depressive disorder is a serious, debilitating, and prevalent psychiatric condition. While most electrophysiological studies focus on firing patterns, such measures may miss how depression alters coordinated activity across circuits. In contrast, multivariate brain criticality can capture network-level state changes reflecting proximity to critical dynamics, which are not evident from firing patterns alone. Here, we assess whether criticality features capture a separable network state signature between depressive and control groups.C57BL/6 mice received chronic corticosterone administration to induce a depression-like state (CORT), and the control group received β-CD vehicle (control). Behaviour was assessed using the novelty-suppressed feeding test. Animals were then implanted with a 4-shank 32-channel probe targeting hippocampus, and spontaneous neural activity was recorded under urethane anaesthesia (Figure. a.). Neural activities were pre-processed with Kilosort2 for downstream analysis. We quantified criticality including branching ratio, avalanche size and duration, and deviation of criticality coefficient (DCC).
CORT animals showed depression-like phenotype in behaviour test (Figure. b, and c). In hippocampal spiking dynamics, the CORT group exhibited a lower branching ratio than controls, shorter avalanche size and duration, and higher DCC (Figure. d-g). The reduced branching ratio suggests weaker propagation of activity across hippocampal network, producing smaller and briefer avalanches. The elevated DCC indicates that brain in the CORT group shows a larger deviation from criticality. Together, these results indicate a shift away from critical-like dynamics.