Biology subjects

Sherafati, A.

Publications and source records attributed to Sherafati, A..

4 recordsLinked to original sources

bioRxiv2025

Functional Connectivity Localizes a Distributed Supramodal Core for Naturalistic Viewing

Understanding the brain mechanisms that support naturalistic perception is a central goal of cognitive neuroscience. Research has progressed from studying the brain with simple unimodal stimuli to employing richer paradigms that engage visual, auditory, and language modalities in naturalistic environments. Recent multimodal encoding models have shown strong promise in modeling and predicting neural responses to such complex stimuli. Previous studies, however, have primarily focused on two modalities (visual and auditory) and often highlight regions implicated in audiovisual processing (e.g., posterior STS), but do not delineate a compact, replicable subnetwork for multimodal, naturalistic stimuli. While these studies produced valuable maps of sensory integration, their scope was restricted to two modalities and they lacked replication, leaving the full picture of the multimodal integration uncertain. Moreover, no studies have localized a compact, replicable subnetwork via FC-guided ablation under naturalistic viewing. The present study advances our understanding of naturalistic perception by identifying the most informative parcels in Schaefers brain atlas that contribute to this task. Building on our earlier work demonstrating that functional connectivity can reveal parcels critical for naturalistic perception, we refine this approach by applying "top drop/bottom drop" and "top keep/bottom keep" selection strategies as well as "broken-stick" analysis to focus on regions most relevant for multimodal integration during naturalistic viewing.

neuroscience↗

bioRxiv2023

A high-density diffuse optical tomography dataset of naturalistic viewing

Traditional laboratory tasks offer tight experimental control but lack the richness of our everyday human experience. As a result, many cognitive neuroscientists have been motivated to adopt experimental paradigms that are more natural, such as stories and movies. Here we describe data collected from 58 healthy adult participants (aged 18-76 years) who viewed 10 minutes of a movie (The Good, the Bad, and the Ugly, 1966). Most (36) participants viewed the clip more than once, resulting in 106 sessions of data. Cortical responses were mapped using high-density diffuse optical tomography (first-through fourth nearest neighbor separations of 1.3, 3.0, 3.9, and 4.7 cm), covering large portions of superficial occipital, temporal, parietal, and frontal lobes. Consistency of measured activity across subjects was quantified using intersubject correlation analysis. Data are provided in both channel format (SNIRF) and projected to standard space (NIfTI) using an atlas-based light model. These data are suitable for methods exploration as well as investigating a wide variety of cognitive phenomena.

neuroscience↗

bioRxiv2021

Dorsolateral prefrontal cortex supports speech perception in listeners with cochlear implants

Cochlear implants are neuroprosthetic devices that can restore hearing in people with severe to profound hearing loss by electrically stimulating the auditory nerve. Because of physical limitations on the precision of this stimulation, the acoustic information delivered by a cochlear implant does not convey the same level of acoustic detail as that conveyed by normal hearing. As a result, speech understanding in listeners with cochlear implants is typically poorer and more effortful than in listeners with normal hearing. The brain networks supporting speech understanding in listeners with cochlear implants are not well understood, partly due to difficulties obtaining functional neuroimaging data in this population. In the current study, we assessed the brain regions supporting spoken word understanding in adult listeners with right unilateral cochlear implants (n=20) and matched controls (n=18) using high-density diffuse optical tomography (HD-DOT), a quiet and non-invasive imaging modality with spatial resolution comparable to that of functional MRI. We found that while listening to spoken words in quiet, listeners with cochlear implants showed greater activity in left prefrontal cortex than listeners with normal hearing, specifically in a region engaged in a separate spatial working memory task. These results suggest that listeners with cochlear implants require greater cognitive processing during speech understanding than listeners with normal hearing, supported by compensatory recruitment of left prefrontal cortex.

neuroscience↗

bioRxiv2020

Global Motion Detection and Censoring in High-Density Diffuse Optical Tomography

Motion-induced artifacts can significantly corrupt optical neuroimaging, as in most neuroimaging modalities. For high-density diffuse optical tomography (HD-DOT) with hundreds to thousands of source-detector pair measurements, motion detection methods are underdeveloped relative to both functional magnetic resonance imaging (fMRI) and standard functional near-infrared spectroscopy (fNIRS). This limitation restricts the application of HD-DOT in many challenging situations and subject populations (e.g., bedside monitoring and children). Here, we evaluate a new motion detection method for multichannel optical imaging systems that leverages spatial patterns across channels. Specifically, we introduce a global variance of temporal derivatives (GVTD) metric as a motion detection index. We show that GVTD strongly correlates with external measures of motion and has high sensitivity and specificity to instructed motion - with area under the receiver operator characteristic curve of 0.88, calculated based on five different types of instructed motion. Additionally, we show that applying GVTD-based motion censoring on both task and resting state HD-DOT data with natural head motion results in an improved spatial similarity to fMRI mapping for the same respective protocols (task or rest). We then compare the GVTD similarity scores with several commonly used motion correction methods described in the fNIRS literature, including correlation-based signal improvement (CBSI), temporal derivative distribution repair (TDDR), wavelet filtering, and targeted principal component analysis (tPCA). We find that GVTD motion censoring outperforms other methods and results in spatial maps more similar to matched fMRI data.

neuroscience↗