Biology subjects

Molotchnikoff, S.

Publications and source records attributed to Molotchnikoff, S..

3 recordsLinked to original sources

bioRxiv2024

Distinct mechanisms of visual and sound adaptation in the cat visual cortex

Sensory areas exhibit modular selectivity to stimuli, but they can also respond to features outside of their basic modality. Several studies have shown cross-modal plastic modifications between visual and auditory cortices; however, the exact mechanisms of these modifications are yet not completely known. To this aim, we investigated the effect of 12 minutes of visual vs. sound adaptation [forceful application of a non-optimal stimulus to a neuron(s) under observation] on the infra- and supra-granular primary visual neurons (V1) of the cat (Felis catus). Previous reports showed that both protocols induced orientation tuning shifts, but sound increased the bandwidths. Here, we compared visual vs. sound adaptation effects, specifically analysing the raw tuning curves by computing the area under the curve (AUC) on a trial-by-trial basis. We report that sound adaptation elicited broader tuning curves accompanied with increased variance in the supra- and infra-granular layers, compared with visual adaptation. These findings suggest unique modulation of dendritic structure by distinct adaptation protocols, resulting in disparate tunings. We suggest that broader tuning curves after sound adaptation may keep the visual cortex prepared across a spectrum of abstract representations that match with visual stimuli.

neuroscience↗

bioRxiv2023

Adaptation-induced sharpening of orientation tuning curves in the mouse visual cortex

Orientation selectivity is an emergent property of visual neurons across species with columnar and non-columnar organization of the visual cortex. To compute the orientation selectivity of a neuron, a tuning function is fit on the raw responses of a neuron and then a measure, termed orientation selectivity index (OSI), is derived from this fitted curve to determine the tuning of the neuron. Previously, it has been shown that adaptation (a protocol where a neuron under observation is presented a non-optimal stimulus for a specific time) has varying effects on the tuning properties of neurons, such as, orientation, spatial frequency, motion etc. The emergence of OSI is more established in columnar cortices than the non-columnar ones. However, how adaptation impinges upon the OSI of the latter has not been systematically investigated. Here, in the mouse primary visual cortex (V1), we show that a 12-min adaptation protocol sharpens the OSI (tuning) of the visual neurons, underlying a specific dendritic neural mechanism, potentially facilitating the learning of novel features.

neuroscience↗

bioRxiv2018

Sound induces change in orientation preference of V1 neurons: Audio-visual cross-influence

In the cortex, demarcated unimodal sensory regions often respond to unforeseen sensory stimuli and exhibit plasticity. The goal of the current investigation was to test evoked responses of primary visual cortex (V1) neurons when an adapting auditory stimulus is applied in isolation. Using extracellular recordings in anesthetized cats, we demonstrate that, unlike the prevailing observation of only slight modulations in the firing rates of the neurons, sound imposition in isolation entirely shifted the peaks of orientation tuning curves of neurons in both supra- and infragranular layers of V1. Our results suggest that neurons specific to either layer dynamically integrate features of sound and modify the organization of the orientation map of V1. Intriguingly, these experiments present novel findings that the mere presentation of a prolonged auditory stimulus may drastically recalibrate the tuning properties of the visual neurons and highlight the phenomenal neuroplasticity of V1 neurons.\n\nHighlightsO_LIProlonged application of sound shifts preferred orientation of neurons in area 17 of cats.\nC_LIO_LIOrientation tuning shifts in the individual neurons in supra- and infragranular layers of V1.\nC_LIO_LISupra- and infragranular layers of V1 operate together but also as distinct compartments following sound adaptation.\nC_LIO_LIVisual cortex is specifically and dynamically impacted by non-visual stimuli.\nC_LIO_LISound adaptation certainly modifies the organization of orientation maps in V1.\nC_LI

neuroscience↗