Biology subjects

Walbrin, J.

Publications and source records attributed to Walbrin, J..

7 recordsLinked to original sources

bioRxiv2026

Grasping at the organization of object knowledge: testing different object-related dimensions as organizational principles of ventral temporal cortex.

In our daily lives we encounter a myriad of things with which we might need to interact as we navigate our environment. Mental representations of these things must be computed and stored in our brains to be manipulated to support cognition. How are such representations organized in the brain? Several proposals have been put forth on what the principles of organization of object information in the brain might be: within ventral temporal cortex - regions thought to support object recognition - possible dimensions include the animacy status of target stimuli, their real size, their texture and material properties, and potentially their graspable status, amongst others. Here we used functional magnetic resonance imaging (fMRI) and multivariate approaches to discriminate patterns of activation for different categories of objects to test the role of these dimensions as organizing principles of object information in the brain. We show that pattern discriminability between different categories of objects does not seem to follow differences in their animacy status in any continuous way. Moreover, graspability of the target stimuli and their haptic texture properties are better predictors of representational content within ventral temporal cortex than animacy and real size. These results are in line with recent studies demonstrating the importance of computational contingencies superimposed by bi-directional functional coupling between parietal regions dedicated to the processing of object manipulation and grasping and ventral temporal regions responsible for object recognition, potentially involving material and texture processing.

neuroscience↗

bioRxiv2024

fMROI: a simple and adaptable toolbox for easy region-of-interest creation

This study introduces fMROI, an open-source software designed for creating regions-of-interest (ROIs) and visualizing magnetic resonance imaging data. fMROI offers a user-friendly graphical interface that simplifies the creation of complex ROIs. It is compatible with various operating systems and enables the integration of user-specified algorithms. Comparative analysis against popular neuroimaging software demonstrates the feasibility, applicability, and ease of use of fMROI. Notably, fMROIs interactive graphical interface with a real-time viewer allows users to identify inconsistencies and design more accurate ROIs, saving significant time by avoiding errors before storing ROIs as NIfTI files. Additionally, fMROI supports automation through command-line accessibility, making it ideal for large-scale analyses. As an open-source platform, fMROI provides a valuable resource for researchers in the neuroimaging community, facilitating efficient ROI creation and streamlining neuroimage analysis.

neuroscience↗

bioRxiv2023

Neural and behavioral signatures of the multidimensionality of manipulable object processing.

Understanding how we recognize everyday objects requires unravelling the variables that govern the way we think about objects and the way in which our representations are organized neurally. A major hypothesis is that the organization of object knowledge follows key object-related dimensions, analogously to how sensory information is organized in the brain. Here, we explored, behaviorally and neurally, the multidimensionality of object processing. We focused on within-domain object information as a proxy for the kinds of object decision tasks we typically engage in our daily lives - e.g., identifying a knife from other types of manipulable objects such as spoons, axes or screwdrivers. To do so, we extracted object-related dimensions from subjective human judgments on a set of objects from a particular object domain - i.e., manipulable objects. We demonstrated that the extracted dimensions are cognitively interpretable - i.e., participants are able to label them; are cognitively relevant for manipulable object processing - i.e., categorization decisions are guided by these dimensions; and are important for the neural organization of knowledge - i.e., they are good predictors of the neural signals elicited by manipulable objects. This shows that multidimensionality is a hallmark of the organization of object knowledge in the brain.

neuroscience↗

bioRxiv2021

The Ventrolateral Anterior Temporal Lobe is Commonly Engaged by Both Mental State Inference and Semantic Association Tasks

A key challenge for neurobiological models of social cognition is to elucidate whether brain regions are specialised for that domain. In recent years, discussion surrounding the role of anterior temporal regions epitomises such debates; some argue the anterior temporal lobe (ATL) is part of a domain-specific network for social processing, while others claim it comprises a domain-general hub for semantic representation. In the present study, we used ATL-optimised fMRI to map the contribution of different ATL structures to a variety of paradigms frequently used to probe a crucial social ability, namely theory of mind (ToM). Using multiple tasks enables a clearer attribution of activation to ToM as opposed to idiosyncratic features of stimuli. Further, we directly explored whether these same structures are also activated by a non-social task probing semantic representations. We revealed that common to all of the tasks was activation of a key ventrolateral ATL region that is often invisible to standard fMRI. This constitutes novel evidence in support of the view that the ventrolateral ATL contributes to social cognition via a domain-general role in semantic processing, and against claims of a specialised social function.

neuroscience↗

bioRxiv2021

High-level representations in human occipito-temporal cortex are indexed by distal connectivity

Human object recognition is dependent on occipito-temporal cortex, but a complete understanding of the complex functional architecture of this area must account for how it is connected to the wider brain. Converging functional magnetic resonance imaging evidence shows that univariate responses to different categories of information (e.g. faces, bodies, & non-human objects) are strongly related to, and potentially shaped by, functional and structural connectivity to the wider brain. However, to date, there have been no systematic attempts to determine how distal connectivity and complex local high-level responses in occipito-temporal cortex (i.e. multivoxel response patterns) are related. Here, we show that distal functional connectivity is related to, and can reliably index, high-level representations for several visual categories (i.e. tools, faces, & places) within occipito-temporal cortex; that is, voxels sets that are strongly connected to distal brain areas show higher pattern discriminability than less well-connected sets do. We further show that, in several cases, pattern discriminability is higher in sets of well-connected voxels than sets defined by local activation (e.g. strong amplitude responses to faces in fusiform face area). Together, these findings demonstrate the important relationship between the complex functional organization of occipito-temporal cortex and wider brain connectivity. Significance statementHuman object recognition relies strongly on occipito-temporal cortex (OTC), yet responses in this broad area are often considered in relative isolation to the rest of the brain. We employ a novel connectivity-guided voxel selection approach with functional MRI data to show higher sensitivity to information (i.e. higher multivoxel pattern discriminability) in voxel sets that share strong connectivity to distal brain areas, relative to: 1) voxel sets that are less-strongly connected; and in several cases 2) voxel sets that are defined by strong local response amplitude. These findings underscore the importance of distal contributions to local processing in OTC.

neuroscience↗

bioRxiv2019

Let’s take a break: Head motion during fMRI tasks is reduced in children and adults if data acquisition is distributed across sessions or days

Head motion remains a challenging confound in functional magnetic resonance imaging (fMRI) studies of both children and adults. Most pediatric neuroimaging labs have developed experience-based, child-friendly standards concerning e.g. the maximum length of a session or the time between mock scanner training and actual scanning. However, it is unclear which factors of child-friendly neuroimaging approaches are effective in reducing head motion. Here, we investigate three main factors including (i) time lag of mock scanner training to the actual scan, (ii) prior scan time, and (iii) task engagement in a dataset of 77 children (aged 6-13) and 64 adults (aged 18-35) using a multilevel modeling approach. In children, distributing fMRI data acquisition across multiple same-day sessions reduces head motion. In adults, motion is reduced after inside-scanner breaks. Despite these positive effects of splitting up data acquisition, motion increases over the course of a study as well as over the course of a run in both children and adults. Our results suggest that splitting up fMRI data acquisition is an effective tool to reduce head motion in general. At the same time, different ways of splitting up data acquisition benefit children and adults. HighlightsO_LIIn children, fMRI data acquisition split into multiple sessions reduces head motion C_LIO_LIIn adults, fMRI data acquisition split by inside-scanner breaks reduces head motion C_LIO_LIIn both children and adults, motion increases over the duration of a study C_LIO_LIIn both children and adults, motion increases over the duration of a run C_LI

neuroscience↗

bioRxiv2019

Developmental Changes in Visual Responses to Social Interactions

Recent evidence demonstrates that a region of the posterior superior temporal sulcus (pSTS) is selective to visually observed social interactions in adults. In contrast, we know comparatively little about neural responses to social interactions in children. Here, we used fMRI to ask whether the pSTS would be tuned to social interactions in children at all, and if so, how selectivity might differ from adults. This was investigated not only in the pSTS, but also in socially-tuned regions in neighbouring temporal cortex: extrastriate body area (EBA), face-selective STS (STS-F), fusiform face area (FFA), and temporo-parietal junction (TPJ-M).\n\nBoth children and adults showed selectivity to social interaction within right pSTS, while only adults showed selectivity on the left. Adults also showed both more focal and greater selectivity than children (6-12 years) bilaterally. Exploratory sub-group analyses showed that younger children (6-8 years), but not older children (9-12), are less selective than adults on the right, while there was a developmental trend (adults > older > younger) in left pSTS. These results suggest that, over development, the neural response to social interactions is characterized by increasingly more selective, more focal and more bilateral pSTS responses, a process that likely continues into adolescence.\n\nHighlightsO_LIChildren show less interaction selectivity in the pSTS than adults\nC_LIO_LIAdults show bilateral pSTS selectivity, while children are more right-lateralized\nC_LIO_LIExploratory findings suggest interaction selectivity in pSTS is more focally tuned in adults\nC_LI

neuroscience↗