Biology subjects

Nandi, B.

Publications and source records attributed to Nandi, B..

6 recordsLinked to original sources

bioRxiv2026

Individualized brain-body signatures of positive emotions revealed by large-scale multimodal neurophysiological recording

Using one of the most comprehensive multimodal biosensing datasets in affective research, densely sampled within individuals, we asked how emotions are instantiated in each person's brain and body. Four participants viewed 168 emotion-evoking videos during 128-channel EEG and 28 autonomic, ocular and facial recordings. Cross-validated elastic-net classifiers distinguished each of 15 positive and neutral emotions from baseline in every participant (mean accuracy 87-97%). We found that no emotion was predicted by a single marker and each reflected a multimodal ensemble of cortical and autonomic activity whose composition was largely person-specific. Yet physiology-derived groupings converged selectively with self-report; Interest-Awe-Amusement-Satisfaction and Entrancement-Aesthetic Appreciation recurred across individuals based on physiology. Across emotion groups, frontal and posterior delta, posterior alpha and electrodermal activity formed a shared backbone, plausibly reflecting affective and sensory engagement, whereas cardiovascular and facial signals varied between people. This framework yields individualized, objective neurophysiological indicators of emotion, potentially aiding personalized diagnosis.

neuroscience↗

bioRxiv2026

Structure of a sparsely populated chimeric intermediate that facilitates fold-switching of a metamorphic protein

Metamorphic proteins challenge the structure-function paradigm by switching between distinct folds. However, the conformational states sampled along the fold-switching pathway have remained elusive because they are transient and unstable. Using multinuclear chemical exchange saturation transfer and relaxation dispersion nuclear magnetic resonance, combined with chemical shift-based structure determination and protein engineering, we visualized the atomic-resolution structure of an invisible state of the metamorphic chemokine lymphotactin. This state is a chimera that integrates the secondary and tertiary structure of one fold with the quaternary assembly of the other. Locking lymphotactin into a single conformation abolishes access to this state, supporting its role as an on-pathway intermediate in metamorphosis. The stabilization of such hybrid intermediates is likely to have facilitated the evolution of fold switching and represent a powerful strategy for protein design.

biophysics↗

bioRxiv2025

High extraversion enhances attentional control through dynamic network reorganization

The extraversion-introversion dimension of personality is hypothesized to differ based on low or high cortical arousal, respectively. Notably, high cortical arousal in introverts is thought to underlie increased distractibility. Here, we assess fMRI while participants meditate (focused attention to their breath) under three levels of auditory distraction: no, low and high. Whereas introverts exhibited worsening attentional focus on their breath with increasing distraction, extraverts retained their ability to focus attention despite distraction. Dynamic functional connectivity analysis indicated that extraverts exhibited less globally efficient and less modular networks, which may prevent distracting stimuli from creating interference. Furthermore, connectivity strengths amongst the default mode, central executive, and salience networks were increased for extraverts and decreased in introverts during high focused attention; potentially indicating distinct cognitive processes that support attentional control. These findings support the hypothesis regarding differing levels of cortical arousal in extraverts and introverts and extend personality theory by linking the extraversion dimension to attentional control and functional connectivity dynamics.

neuroscience↗

bioRxiv2022

Functional regulation of an intrinsically disordered protein via a conformationally excited state

A longstanding goal in the field of intrinsically disordered proteins (IDP) is to characterize their structural heterogeneity and pinpoint the role of this heterogeneity in IDP function. Here, we use multinuclear chemical exchange saturation (CEST) NMR to determine the structure of a thermally accessible globally folded excited state in equilibrium with the intrinsically disordered native ensemble of a bacterial transcriptional regulator CytR. We further provide evidence from double resonance CEST experiments that the excited state, which structurally resembles the DNA-bound form of CytR, recognizes DNA by means of a folding-before-binding conformational selection pathway. The disorder-to-order regulatory switch in DNA recognition by natively disordered CytR therefore operates through a dynamical variant of the lock-and-key mechanism where the structurally complementary conformation is transiently accessed via thermal fluctuations. One-Sentence SummaryThe intrinsically disordered cytidine repressor binds DNA via a folding-before-binding conformational selection mechanism

biophysics↗

bioRxiv2020

Integrated genomic view of SARS-CoV-2 in India

India first detected SARS-CoV-2, causal agent of COVID-19 in late January-2020, imported from Wuhan, China. March-2020 onwards; importation of cases from rest of the countries followed by seeding of local transmission triggered further outbreaks in India. We used ARTIC protocol based tiling amplicon sequencing of SARS-CoV-2 (n=104) from different states of India using a combination of MinION and MinIT from Oxford Nanopore Technology to understand introduction and local transmission. The analyses revealed multiple introductions of SARS-CoV-2 from Europe and Asia following local transmission. The most prevalent genomes with patterns of variance (confined in a cluster) remain unclassified, here, proposed as A4-clade based on its divergence within A-cluster. The viral haplotypes may link their persistence to geo-climatic conditions and host response. Despite the effectiveness of non-therapeutic interventions in India, multipronged strategies including molecular surveillance based on real-time viral genomic data is of paramount importance for a timely management of the pandemic.

microbiology↗

bioRxiv2018

Inferring the direction of rhythmic neural transmission via inter-regional phase-amplitude coupling (ir-PAC)

Phase-amplitude coupling (PAC) estimates the statistical dependence between the phase of a low-frequency and the amplitude of a high-frequency component of local field potentials (LFP). Characterizing the relationship between nested oscillations in LFPs, PAC has become a powerful tool for understanding neural dynamics in both animals and humans. In this work, we introduce a new application for this measure to two LFPs to infer the direction and strength of rhythmic neural transmission between distinct networks. Based on recently accumulating evidence that transmembrane currents related to action potentials contribute a broad-band component to LFP in the high-gamma band, we hypothesized that PAC calculated between high-gamma in one LFP and low-frequency oscillations in another would relate the output (spiking) of one area to the input (soma/dendritic postsynaptic potentials) of the other. We tested this hypothesis on theta-band long range communications between hippocampus and prefrontal cortex (PFC) and theta-band short range communications between different regions within the hippocampus. The results were interpreted within the known anatomical connections predicting hippocampus[->]PFC and DG[->]CA3[->]CA1, i.e., theta transmission is unidirectional in both cases: from hippocampus to PFC and along the tri-synaptic pathway within hippocampus. We found that (1) hippocampal high-gamma amplitude was significantly coupled to theta phase in PFC, but not vice versa; (2) similarly, high-gamma amplitude in DG was significantly coupled to CA1 theta phase, but not vice versa, and (3) the DG high-gamma-CA1 theta PAC was significantly correlated with DG[->]CA1 Granger causality, a well-established analytical measure of directional neural transmission. These results support the hypothesis that inter-regional PAC (ir-PAC) can be used to relate the output of a \"driver\" network (i.e., high gamma) to the input of a \"receiver\" network (i.e., theta) and thereby establish the direction and strength of rhythmic neural transmission.

neuroscience↗