Biology subjects

Opalka, A. N.

Publications and source records attributed to Opalka, A. N..

3 recordsLinked to original sources

bioRxiv2025

Anterior cingulate cortex in complex associative learning: monitoring action state and action content

Environmental changes necessitate adaptive responses, and thus the ability to monitor ones actions and their connection to specific cues and outcomes is crucial for survival. The anterior cingulate cortex (ACC) is implicated in these processes, yet its precise role in action monitoring versus outcome tracking remains unclear. To investigate this, we developed a novel discrimination-avoidance task for mice, designed with clear temporal separation between actions and outcomes. Our findings show that ACC neurons primarily encode post-action variables over extended periods, reflecting the animals preceding actions rather than the outcomes or values of those actions. Specifically, we identified two distinct subpopulations of ACC neurons: one encoding the action state (whether an action was taken) and the other encoding the action content (which action was taken). Importantly, increased post-action ACC activity was associated with better performance in subsequent trials. These findings suggest that the ACC supports complex associative learning through extended signaling of rich action-relevant information, thereby bridging cue, action, and outcome associations.

neuroscience↗

bioRxiv2024

A distinct down state assembly in retrosplenial cortex during slow-wave sleep

Understanding the intricate mechanisms underlying slow-wave sleep (SWS) is crucial for deciphering the brains role in memory consolidation and cognitive functions. It is well-established that cortical delta oscillations (0.5-4 Hz) coordinate communications among various cortical, hippocampal, and thalamic regions during SWS. These delta oscillations have periods of Up and Down states, with the latter previously thought to represent complete cortical silence; however, new evidence suggests that Down states serve important functions for information exchange during memory consolidation. The retrosplenial cortex (RSC) stands out for its pivotal role in memory consolidation due to its extensive connectivity with memory-associated regions, although it remains unclear how RSC neurons engage in delta-associated consolidation processes. Here, we employed multi-channel in vivo electrophysiology to study RSC neuronal activity in freely behaving mice during natural SWS. We discovered that the RSC contains a discrete assembly of putative excitatory neurons ([~]20%) that initiated firing at SWS Down states and reached maximal firing at the Down-to-Up transitions. Therefore, we termed these RSC neurons the Down state assembly (DSA), and the remaining RSC excitatory neurons as non-DSA. Compared to non-DSA, DSA neurons exhibit a higher firing rate, larger cell body size, and no connectivity with nearby RSC neurons. Subsequently, we investigated RSC neuronal activity during a contextual fear conditioning paradigm and found that both DSA and non-DSA neurons exhibited increased firing activity during post-training sleep compared to pre-training sleep, indicating their roles in memory consolidation. Lastly, optogenetics combined with electrophysiology revealed that memory-associated inputs differentially innervated RSC excitatory neurons. Collectively, these findings provide insight on distinct RSC neuronal subpopulation activity in sleep and memory consolidation.

neuroscience↗

bioRxiv2020

Hippocampal efferents to retrosplenial cortex and lateral septum are required for memory acquisition

Learning and memory involves a large neural network of many brain regions, including the notable hippocampus along with the retrosplenial cortex (RSC) and lateral septum (LS). Previous studies have established that the dorsal hippocampus (dHPC) plays a critical role during the acquisition and expression of episodic memories. However, the role of downstream circuitry from the dHPC, including the dHPC-to-RSC and dHPC-to-LS pathways, has come under scrutiny only recently. Here, we employed an optogenetic approach with contextual fear conditioning in mice to determine whether the above two pathways are involved in acquisition and expression of contextual fear memory. We found that a selective inhibition of the dHPC neuronal terminals in either the RSC or LS during acquisition impaired subsequent memory performance, suggesting that both the dHPC-to-RSC and dHPC-to-LS pathways play a critical role in memory acquisition. We also selectively inhibited the two dHPC efferent pathways during memory expression and found a differential effect on memory performance. These results indicate the intricacies of memory processing and that hippocampal efferents to cortical and subcortical regions may be differentially involved in aspects of physiological and cognitive memory processes.

neuroscience↗