Biology subjects

Bhattacharjee, A. S.

Publications and source records attributed to Bhattacharjee, A. S..

6 recordsLinked to original sources

bioRxiv2025

Decision revisions modulated by synaptic inhibition in the olfactory bulb facilitate learning

Behavioral responses are preceded by decisions based on perceived sensory evidence. In real life, sensory inputs are often noisy and change incessantly, raising the question of when and how accurate decisions are made. Cognitive flexibility allows us to revise the choices in case of perceptual conflicts, leading to response revisions. This involves switching between available choices or rapidly stopping misconstrued responses. Here, we quantified these erroneous behavioral actions and studied the underlying neural mechanisms. Mice were trained on an olfactory decision-making task wherein they had to distinguish between a rewarded and an unrewarded stimulus by responding with a lick or withholding it. While the animals respond by licking for both rewarded and unrewarded odor stimuli at the initial stages of learning, the responses almost disappear for the unrewarded ones in the learned stage. However, animals tend to initiate lick responses and stop within a few milliseconds for a few unrewarded trials, even when accuracy levels are high. We describe this phenomenon as decision revisions (DR), and observed it in 5-25% of trials among high-performance blocks. These revisions were mostly observed within a few hundred milliseconds of stimulation. We observed a significantly higher number of revision trials for binary odor mixture discriminations compared to monomolecular ones. Further, by enhancing inhibitory synaptic signaling in the olfactory bulb through photoactivation of ChR2-expressing GAD65-positive GABAergic interneurons, we observed faster odor discrimination and fewer revision trials. Thus, our findings confirm decision revisions that are stimulus complexity-dependent and the pre-cortical control over such a complex cognitive activity. Highlights of the studyO_LIMice revise context-inappropriate responses in a Go/No-go task. C_LIO_LIMice correct errors as they learn. C_LIO_LIDecision revisions are shaped by stimulus complexity. C_LIO_LIOptogenetic activation of the olfactory bulb inhibitory interneurons modulates decision revisions. C_LI

neuroscience↗

bioRxiv2024

The claustrum is critical for maintaining working memory information

Working memory (WM) enables the mammalian brain to temporarily store and manipulate information, supporting cognitive tasks and communication processes1,2. Rather than depending on a single specialized area, WM is thought to operate through a distributed network spanning cortical and subcortical regions3-5. A dedicated WM storage area would likely require broad reciprocal connections with various cortical regions to accommodate the diverse range of information WM retains. The claustrum (CLA), with its extensive bidirectional connections to the neocortex6-9, presents a compelling candidate for such a role. Here, we examined the involvement of the CLA in WM processes by recording CLA neuronal activity in mice engaged in olfactory and tactospatial delayed non-match-to-sample WM tasks. We identified cue- selective and delay-specific neurons in the CLA that maintained activity for tens of seconds after the stimulus presentation ended. Additionally, population activity in the CLA allowed for decoding of cue identity post-stimulus, although this signal gradually declined over time, aligning with animal behavior. Remarkably, both chemo- and optogenetic inhibition of CLA neurons severely impaired WM performance across multiple types of stored information, highlighting the CLAs critical role during both cue encoding, delay periods, and target comparison phases. These findings challenge the view that no single brain area is essential for WM storage and support a role for the CLA as an essential WM storage hub.

neuroscience↗

bioRxiv2024

Mouse olfactory system acts as anemo-detector and -discriminator

Airflow detection while smelling is a fundamental requirement for olfaction, yet the mechanisms underlying such multimodal processing in the olfactory system remain unknown. We report here that mice can learn to accurately discriminate airflow with parallel processing of both mechanical and chemical stimuli revealed by modulated sniffing and refined calcium signaling in the olfactory bulb inhibitory network. Genetic perturbation of AMPAR function and optogenetic control bidirectionally shifted airflow discrimination learning pace, with contrasting phenotypes observed for odor learning, engagement of inhibitory circuits, and setting the optimal inhibition level for stimulus refinement. Multimodal odor-airflow stimuli at subthreshold levels enhanced learning, demonstrating that mechanical stimuli heighten olfactory perception. Our results, thus explain the multimodality of olfaction, and reveal an unexplored dimensionality of odor perception.

neuroscience↗

bioRxiv2022

Uncertainty revealed by delayed responses during olfactory matching

Matching of olfactory stimuli involves both sensory and higher cognitive functioning. Different decision processes such as detection and discrimination, along with holding the perceived information are involved during the matching process. Accuracy and decision times, the interdependent readouts, can define the uncertainty involved in matching of sensory stimuli. To probe sensory and cognitive functions involving olfactory system in human subjects, we have developed a novel olfactory matching paradigm using an automated custom-built olfactory-action meter. With precise and consistent odor delivery and real-time data analysis, our system automates the entire process without any intervention by the experimenter, making it suitable as a diagnostic tool for quantifying olfactory and neurocognitive fitness. In around 400 healthy human subjects, with mean detection accuracy of 90%, we observed significantly better olfactory matching performance for simple monomolecular odors, in comparison to complex binary odor mixtures. Odor matching accuracy declined significantly with the increase in odor complexity. Olfactory matching was more rapid when subjects made correct versus incorrect decisions, indicating perceptual certainty. Subjects also took longer matching time for complex odors compared to simple odor stimuli. Thus, olfactory matching that provides a combined readout of sensory and cognitive fitness, establishes a direct link between the performance accuracy and the certainty of decisions.

neuroscience↗

bioRxiv2022

Motifizer: a tool for parsing high-throughput sequencing datasets and quantitative comparative analyses of transcription factor-binding sites

BackgroundComparative analysis of Chromatin immunoprecipitation followed by massively parallel sequencing (ChIP-seq), combined with transcriptomics data (RNA-seq), can provide critical insights into gene regulatory networks controlled by transcription factors in a given biological context. While multiple programs exist, which need to be individually installed and executed to generate such information, a user-friendly tool with low system requirements which combines the various computational processes into one package, using a docker container, is lacking. ResultsIn this study, we present a user-interactive, infrastructure-independent computational pipeline, called Motifizer, which uses open source tools for processing ChIP-Seq and RNA-seq datasets. Motifizer performs extensive analysis of raw input data, performing peak calling, de-novo motif analysis and differential gene expression analysis on ChIP and RNA-seq datasets. Additionally, Motifizer can be used for analysis and quantitative comparison of transcription factor binding sites in user defined genomic regions. Motifizer also allows easy addition and/or changes of parameters, thereby adding to the versatility of the tool. ConclusionThe Motifizer tool is an easy to use tool which uses a docker container system to install and execute ChIP-seq and RNA-seq data parsing. The Analysis module of Motifizer can be employed to identify putative targets involved in gene regulatory networks. Motifizer can be accessed by a large user base and does not require programming skill by the user. Motifizer can be locally installed from the repository (https://github.com/abhikbhattacharjee/Motifizer)

bioinformatics↗

bioRxiv2018

Similarity and strength of glomerular odor representations define neural metric of sniff-invariant discrimination time

The olfactory environment is first represented by glomerular activity patterns in the olfactory bulb. It remained unclear, how these activity patterns intersect with sampling behavior to account for the time required to discriminate odors. Using different classes of volatile stimuli, we investigated glomerular activity patterns and sniffing behavior during olfactory decision-making. Mice discriminated monomolecular odorants and binary mixtures on a fast time scale and learned to increase their breathing frequency at a fixed latency after trial initiation, independent of odor identity. Relative to the increase in breathing frequency, monomolecular odorants were discriminated within 10-40 ms while binary mixtures required an additional 60-70 ms. Intrinsic imaging of odor-evoked glomerular activity maps in anesthetized and awake mice revealed that the Euclidean distance between glomerular patterns elicited by different odors, a measure of similarity and activation strength, was anti-correlated with discrimination time. Therefore, the similarity of glomerular patterns and their activation strengths, rather than sampling behavior, define the extent of neuronal processing required for odor discrimination, establishing a neural metric to predict olfactory discrimination time.

neuroscience↗