Biology subjects

Krishna, G.

Publications and source records attributed to Krishna, G..

3 recordsLinked to original sources

bioRxiv2021

VIP interneurons in mouse whisker S1 exhibit sensory and action-related signals during goal-directed behavior

Vasoactive intestinal peptide-expressing (VIP) interneurons, which constitute 10-15% of the cortical inhibitory neuron population1,2, have emerged as an important cell type for regulating excitatory cell activity based on behavioral state. VIP cells in sensory cortex are potently engaged by neuromodulatory and motor inputs during active exploratory behaviors like locomotion and whisking, which in turn promote pyramidal cell firing via disinhibition3-5. Such state-dependent modulation of activity by VIP cells in sensory cortex has been studied widely in recent years. However, the function of VIP cells during goal-directed behavior is less well understood. It is not clear how task-related events like sensory stimuli, motor actions, or reward activate VIP cells in sensory cortex since there is often temporal overlap in the occurrence of these events. We developed a Go/NoGo whisker touch detection task which incorporates a post-stimulus delay period to separate sensory-driven activity from action- or reward-related activity during behavior. We used 2-photon calcium imaging to measure task-related signals of L2/3 VIP neurons in S1 of behaving mice. We report for the first time that VIP cells in mouse whisker S1 are activated by both whisker stimuli and goal-directed licking. Whisker- and lick-related signals were spatially organized in relation to anatomical columns in S1. Sensory responses of VIP cells were tuned to specific whiskers, whether or not they also displayed lick-related activity.

neuroscience↗

bioRxiv2021

Multiplexed action-outcome representation by striatal striosome-matrix compartments detected with a novel cost-benefit foraging task

Learning about positive and negative outcomes of actions is crucial for survival and underpinned by conserved circuits including the striatum. How associations between actions and outcomes are formed is not fully understood, particularly when the outcomes have mixed positive and negative features. We developed a novel foraging ( bandit) task requiring mice to maximize rewards while minimizing punishments. By 2-photon Ca++ imaging, we monitored activity of 5831 identified anterodorsal striatal striosomal and matrix neurons. Surprisingly, we found that action-outcome associations for reward and punishment were combinatorially encoded rather than being integrated as overall outcome value. Single neurons could, for one action, encode outcomes of opposing valence. Striosome compartments consistently exhibited stronger representations of reinforcement outcomes than matrix, especially for high reward or punishment prediction errors. These findings demonstrate a remarkable multiplexing of action-outcome contingencies by single identified striatal neurons and suggest that striosomal neurons are differentially important in action-outcome learning.

neuroscience↗

bioRxiv2020

Retinoic acid Inducible Gene-I like Receptors Activate Snail and Slug to Limit RNA Viral Infections

RLRs sense cytosolic non-self RNAs including viral RNAs before mounting a response leading to the activation of Type-I IFNs. Here, we identify a previously unknown regulation of Snail, a transcription regulator known in EMT, during RNA viral infections and describe its possible implication. RNA viral infections, poly (I:C) transfection and ectopic expression of RLR components activated Snail and Slug in epithelial cells. Detailed examination revealed that MAVS and phosphorylated IRF3 are essential in this regulation. We identified two ISREs in SNAI1 promoter region and their alterations rendered the promoter non-responsive to phospho-IRF3 in luciferase assay. Ectopic expression of Snail and Slug activated RLR pathway and dramatically limited RNA viral infections in epithelial cells pointing to their antiviral functions. Thus, Snail and Slug are transcriptionally regulated by RLRs in a similar manner as IFN-{beta} and they in turn promote RLR pathway possibly strengthening the antiviral state in the cell.

immunology↗