Biology subjects

Damphousse, C. C.

Publications and source records attributed to Damphousse, C. C..

2 recordsLinked to original sources

bioRxiv2026

Systemic diazepam alters local hippocampal CA1 circuits and differentially affects entorhinal and CA3 inputs

The GABAA positive allosteric modulator diazepam is taken systemically by millions of people daily. GABAA signaling is essential for hippocampal circuit function, but the effects of systemic diazepam on hippocampal information processing during behavior has not been studied. To answer this question, large neural ensembles were recorded from rats running a linear track under systemic diazepam administration. A cross-correlation of spiking activity revealed significantly increased inhibition from interneurons, aligned with the timescale of GABAA, suggesting a direct effect on local circuits. Local field potentials (LFP) showed an increase in theta and lo-gamma (30-50 Hz) power but a decrease in hi-gamma (80-120 Hz) power. We also found decreased amplitude and rate of sharp wave ripple (SWR) events and a reduction of firing rate and proportion of cells recruited to the SWRs. An autocorrelation of single-cell spike trains revealed a decrease and shift from shorter to longer timescales, aligning differently with theta frequencies. Phase coupling measurements showed decreased cellular coupling to theta and increased coupling to lo-gamma and hi-gamma. Finally, entropy of decoding along the track was increased, suggesting less precise spatial representations under diazepam. These changes suggest mechanisms that would likely disrupt hippocampal memory storage and consolidation processes under systemic diazepam.

neuroscience↗

bioRxiv2026

Hippocampal representations differentiate reactive and anticipatory responses during foraging under threat

Adaptive behavior under threat requires balancing reward pursuit against the risk of harm. During approach-avoidance conflict, animals often pause at decision points, but whether these pauses reflect a unified process or distinct decision states remains unclear. Here, we replicate and extend findings from Calvin et al. (2025) by analyzing hippocampal activity in rats performing a pseudo-predator foraging task across two cohorts. We compared mid-track aborts (MTAs), mid-track continues (MTCs), and retreats. Behaviorally, MTAs and MTCs emerged from a shared pause state but diverged in outcome, whereas retreats reflected rapid escape following attack. Despite similar endpoints, retreats and MTAs differed in movement dynamics and neural activity. During retreats, hippocampal representations remained biased toward the attack location. In contrast, representations during MTAs shifted toward safe locations. During pauses, representations differed according to subsequent behavior: pauses preceding MTAs showed greater decoded probability near the attack region, whereas pauses preceding MTCs showed greater decoded probability to goal locations. These differences were present during the outbound approach, suggesting decision-related processes emerged early on in the journey. Together, these findings dissociate hippocampal representations associated with reactive escape from those underlying anticipatory, anxiety-like decision-making, suggesting that the hippocampus dynamically tracks behaviorally relevant features to guide decisions under threat.

neuroscience↗