Biology subjects

Pandit, N. S.

Publications and source records attributed to Pandit, N. S..

3 recordsLinked to original sources

bioRxiv2026

Repetition Selectively Reconfigures Offset-Defined Temporal Integration in Auditory Cortex

Auditory perception requires integrating sound over time, but whether cortical integration windows are fixed or adaptively shaped by recent sensory history remains unclear. Because auditory offset responses are shaped by the temporal structure preceding sound termination, they provide a readout of offset-defined temporal integration. Here, we recorded single-unit activity in awake rat auditory cortex while presenting 512-ms click trains with inter-click intervals of 1, 2, 4, 8 or 16 ms. Each stimulus was repeated ten times, allowing repetition number to index increasing adaptation. Across 271 offset-responsive neurons, repetition strongly compressed the maximal ICI capable of evoking a significant offset response and produced a smaller population-level shift in preferred ICI. These preferred-ICI changes were heterogeneous across neurons, with bidirectional shifts at the single-neuron level. In contrast, the effective temporal window measured with irregular-regular click trains remained stable at the population level, despite neuron-level variability. AAF and A1 further showed distinct repetition-dependent tuning profiles. These findings suggest that adaptation selectively reconfigures ICI-based offset tuning while preserving a population-level local regularity window, revealing flexible and stable components of cortical temporal integration.

neuroscience↗

bioRxiv2025

Temporal boundary gating of auditory sensitivity

Perception unfolds over time, but whether continuous sounds are sampled with uniform sensitivity is unknown. We combine human psychophysics, EEG and rodent neurophysiology to show that local auditory change detection is strongly gated by stimulus boundaries. In humans, brief perturbations inserted at different temporal positions within 0.5-1-s tones revealed an inverted U-shaped sensitivity profile: detection was attenuated near sound onset and offset and maximal mid-epoch, with EEG change responses showing a closely matching dependence on change timing. Electrocorticography in awake rats exhibited homologous temporal weighting, and analogous profiles for amplitude changes and visual motion demonstrated cross-feature and cross-modal generality. To uncover circuit mechanisms, we recorded single units along the inferior colliculus-medial geniculate body-auditory cortex pathway together with laminar local field potentials in A1. Onset-locked suppression of change responses emerged in midbrain and was progressively amplified in thalamus and cortex, whereas the full start-end profile was expressed in granular-layer alpha-gamma power. A simple biophysically grounded model in which onset responses saturate and cortical populations integrate over finite temporal windows recapitulates this pattern, explaining how stimulus boundaries disrupt prospective and retrospective integration and thereby degrade change detection near the beginning and end of sounds.

neuroscience↗

bioRxiv2025

Echoes as Signal, Not Noise: Reverberation Sharpens Sensitivity to Temporal Structure

Sensitivity to temporal structure is fundamental to hearing, yet how natural reverberation shapes this sensitivity is unclear. Here we identify echo-facilitated temporal sensitivity (EFTS), a principle whereby the auditory system exploits echoes to selectively enhance responses to rapid temporal changes. Using transitional click trains with subtle inter-click-interval (ICI) shifts, we first show that increasing echo strength systematically enlarges the sound-level step at ICI transitions in both recorded and simulated stimuli, sharpening the physical boundary between segments of distinct temporal structure. In humans, psychophysical detection of ICI changes improves monotonically with echo level in both simulated and real free-field environments, while a late EEG change response scales with echo strength as onset responses remain comparatively stable. In awake rats, electrocorticography over auditory cortex reveals parallel echo-dependent enhancement of transition-evoked activity. Single units exhibit echo-level-dependent amplification of change-related firing and improved neurometric discriminability. Laminar local field potential and current source density analyses further show that echo-dependent divergence emerges first in granular and infragranular layers before propagating to supragranular cortex, consistent with thalamocortical drive followed by intracortical amplification. Together, these findings establish EFTS as a cross-species mechanism that reframes echoes as structured signals the brain uses to sharpen temporal integration in everyday listening.

neuroscience↗