Biology subjects

Erickson, M. T.

Publications and source records attributed to Erickson, M. T..

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↗

bioRxiv2024

Dorsal hippocampus represents locations to avoid as well as locations to approach during approach-avoidance conflict

Worrying about perceived threats is a hallmark of multiple psychological disorders including anxiety. This concern about future events is particularly important when an individual is faced with an approach-avoidance conflict. Potential goals to approach are known to be represented in the dorsal hippocampus during theta sweeps. Similarly, important non-local information is represented during hippocampal high synchrony events (HSEs), which are correlated with sharp-wave ripples (SWRs). It is likely that potential future threats may be similarly represented. We examined how threats and rewards were represented within the hippocampus during approach-avoidance conflicts in rats faced with a predator-like robot guarding a food reward. We found representations of the pseudo-predator during HSEs when hesitating in the nest, and during theta prior to retreating as the rats approached the pseudo-predator. After the first attack, we observed new place fields appearing at the location of the robot (not the location the rat was when attacked). The anxiolytic diazepam reduced anxiety-like behavior and altered hippocampal local field potentials, including reducing SWRs, suggesting that one potential mechanism of diazepams actions may be through altered representations of imagined threat. These results suggest that hippocampal representation of potential threats could be an important mechanism that underlies worry and a potential target for anxiolytics.

neuroscience↗