Biology subjects

Bulkin, D. A.

Publications and source records attributed to Bulkin, D. A..

3 recordsLinked to original sources

bioRxiv2023

Ventromedial prefrontal parvalbumin neurons are necessary for initiating cued threat avoidance

The infralimbic cortex (IL) is essential for flexible behavioral responses to threatening environmental events. Reactive behaviors such as freezing or flight are adaptive in some contexts, but in others a strategic avoidance behavior may be more advantageous. IL has been implicated in avoidance, but the contribution of distinct IL neural subtypes with differing molecular identities and wiring patterns is poorly understood. Here, we study IL parvalbumin (PV) interneurons in mice as they engage in active avoidance behavior, a behavior in which mice must suppress freezing in order to move to safety. We find that activity in inhibitory PV neurons increases during movement to avoid the shock in this behavioral paradigm, and that PV activity during movement emerges after mice have experienced a single shock, prior to learning avoidance. PV neural activity does not change during movement toward cued rewards or during general locomotion in the open field, behavioral paradigms where freezing does not need to be suppressed to enable movement. Optogenetic suppression of PV neurons increases the duration of freezing and delays the onset of avoidance behavior, but does not affect movement toward rewards or general locomotion. These data provide evidence that IL PV neurons support strategic avoidance behavior by suppressing freezing.

neuroscience↗

bioRxiv2021

Tonic activity in lateral habenula neurons promotes disengagement from reward-seeking behavior

Survival requires both the ability to persistently pursue goals and the ability to determine when it is time to stop, an adaptive balance of perseverance and disengagement. Neural activity in the lateral habenula (LHb) has been linked to aversion and negative valence, but its role in regulating the balance between reward-seeking and disengaged behavioral states remains unclear. Here, we show that LHb neural activity is tonically elevated during minutes-long disengagements from reward-seeking behavior, whether due to repeated reward omission or following sufficient consumption of reward. Further, we show that LHb inhibition extends ongoing reward-seeking behavioral states but does not prompt re-engagement. We find no evidence for similar tonic activity fluctuations in ventral tegmental area (VTA) dopamine neurons. Our findings implicate the LHb as a key mediator of disengagement from reward-seeking behavior in multiple contexts and argue against the idea that the LHb contributes to decisions solely by signaling aversion.

neuroscience↗

bioRxiv2018

Hippocampal State Transitions at the Boundaries between Trial Epochs

The hippocampus encodes distinct environmental and behavioral contexts with unique patterns of activity. Representational shifts with changes in the context, referred to as remapping, have been extensively studied. However, less is known about the nature of transitions between representations. In this study, we leverage a large dataset of 2056 neurons recorded while rats performed an olfactory memory task with a predictable temporal structure involving trials and inter-trial intervals, separated by salient boundaries at the trial start and trial end. We found that trial epochs were associated with stable hippocampal population representations, despite moment to moment variability in stimuli and behavior. Representations of trial and inter-trial interval epochs were far more distinct than spatial factors would predict and the transitions between the two were abrupt, with a sharp boundary suggestive of a dynamic shift in the representational state. This boundary was associated with a large spike in multi-unit activity, with many individual cells specifically active at the start or end of each trial. Both epochs and boundaries were encoded by hippocampal populations, and these representations carried information on orthogonal axes readily identified using principal component analysis. We suggest that the activity spike at trial boundaries might serve to drive hippocampal activity from one stable state to another, and may play a role in segmenting continuous experience into discrete episodic memories.

neuroscience↗