Biology subjects

Agarwalla, S.

Publications and source records attributed to Agarwalla, S..

4 recordsLinked to original sources

bioRxiv2025

Modelling Auditory Enhancement: Efferent Control of Cochlear Gain can Explain Level Dependence and Effects of Hearing Loss

The role of medial olivocochlear (MOC) efferent gain control in auditory enhancement (AE) was investigated using a subcortical auditory model. AE refers to the influence of a precursor on detectability of targets. The absence (or presence) of a precursor component at the target frequency enhances (or suppresses) detection under simultaneous masking conditions. Furthermore, the enhanced target under simultaneous masking acts as a stronger forward masker for a delayed probe tone, known as AE under forward masking. Psychoacoustic studies of AE report findings that challenge conventional expectations, and the underlying mechanisms remain unclear. For instance, listeners with hearing impairment have AE under simultaneous masking but not forward masking (Kreft et al., 2018; Kreft and Oxenham, 2019), whereas listeners with normal hearing have level-dependent AE under forward masking (Kreft and Oxenham, 2019). Our model with MOC efferent gain control successfully replicated these findings. In contrast, a model without efferent gain control failed to capture these effects, supporting the hypothesis that MOC-mediated cochlear gain modulation may play a role in AE and its alteration by hearing loss.

neuroscience↗

bioRxiv2025

Forward masking in the Inferior Colliculus: Dynamics of Discharge-rate Recovery after Narrowband Noise Maskers

In forward masking the detection threshold for a target sound (probe) is elevated due to the presence of a preceding sound (masker). Although many factors are known to influence the probe response following a masker, the current work focused on the temporal separation (delay) between the masker and probe and the inter-trial interval (ITI). Human probe thresholds recover from forward masking within 150-300 ms, similar to neural threshold recovery in the IC within 300 ms after tone maskers. Our study focused on recovery of discharge rate of IC neurons in response to probe tones after narrowband gaussian noise (GN) forward maskers, with varying time delays. Additionally, we examined how prior masker trials influenced IC rates by varying ITI. Our findings showed that previous masker trials impacted probe-evoked discharge rates, with full recovery requiring ITIs over 1.5 s after 70 dB SPL narrowband GN maskers. Neural thresholds in the IC for probes preceded by noise maskers were in the range observed in psychoacoustical studies. Two proposed mechanisms for forward masking, persistence and efferent gain control, were tested using rate analyses or computational modeling. A physiological model with efferent feedback gain control had responses consistent with trends in the physiological recordings.

neuroscience↗

bioRxiv2023

Sex and age independent predictive call sequence alterations of pups in an autism spectrum disorder mouse model

Social communication deficit is a hallmark of autism spectrum disorders (ASDs). Mouse ultrasonic-vocalizations (USVs), with communicative significance, are extensively used to probe vocalization-based social communication impairment. Despite the predictable nature of mouse USVs, very few studies have taken advantage of the same. The current work explores USV pup-isolation-call (PIC) features and alterations in structural content of predictive PIC sequences of the well-established in-utero valproic-acid (VPA) exposure-based ASDs model. Our study shows that along with call features, even higher-order USV structures undergo alterations in the ASDs model at all developmental ages and sexes. Confirming prior observations, we found reduced call rates and durations, as well as heightened peak frequencies in ASD model pups. Our data also highlights trends in call features, syllable composition, and transitions across sexes and age. The ASD female mice exhibited higher within group heterogeneity in syllable composition and transition over age compared to ASD males or typically developing males and females. Analysis of sequences of USVs emitted by pups using mutual information between syllables at different positions revealed that dependencies between syllables were higher in typically developing mice of both sexes compared to ASD model pups. In brief, we found that PICs call features were altered in VPA mouse models both for male and female pups and their vocalizations lack the complex syllable sequence order emitted by typically developing ones. Our studies will help establish and further investigate ASD mouse models to get a clearer picture of abnormalities related to social communication deficits over sexes and age.

neuroscience↗

bioRxiv2021

Social experience dependent plasticity of mouse song selectivity without that of song components

Syllable sequences in male mouse ultrasonic-vocalizations (USVs), "songs", contain structure -quantified through predictability, like birdsong and aspects of speech. Apparent USV innateness and lack of learnability, discount mouse USVs for modelling speech-like social communication and its deficits. Informative contextual natural sequences (SN) were theoretically extracted and they were preferred by female mice. Primary auditory cortex (A1) supragranular neurons show differential selectivity to the same syllables in SN and random sequences (SR). Excitatory neurons (EXNs) in females showed increases in selectivity to whole SNs over SRs based on extent of social exposure with male, but syllable selectivity remained unchanged. Thus mouse A1 single neurons adaptively represent entire order of acoustic units without altering selectivity of individual units, fundamental to speech perception. Additionally, observed plasticity was replicated with silencing of somatostatin positive neurons, which had plastic effects opposite to EXNs, thus pointing out possible pathways involved in perception of sound sequences.

neuroscience↗