Category-selectivity, again: Hand-selective Visual Areas Support Action-related Behavioural Goals
Presented During:
Wednesday, June 26, 2024: 11:30 AM - 12:45 PM
COEX
Room:
Grand Ballroom 104-105
Poster No:
2546
Submission Type:
Abstract Submission
Authors:
Davide Cortinovis1, Stefania Bracci1
Institutions:
1Center for Mind/Brain Sciences, University of Trento, Rovereto, Italy
First Author:
Co-Author:
Introduction:
The occipitotemporal cortex (OTC) contains areas that preferentially respond to specific object categories like faces, body parts, and tools, with a mirrored organization across its lateral and ventral parts (Kanwisher, 2010; Taylor & Downing, 2011). However, the exact role of these areas in supporting action or object recognition and the dimensions they represent are still debated (Bracci & Op de Beeck, 2023; Peelen & Downing, 2017). Here, we investigate the role of the action dimension as one of the possible organizing principles of object space in visual cortex, by investigating the selectivity and the multivariate representations of category-selective clusters.
Methods:
Across two experiments, we collected fMRI data from 47 participants who were presented with static images characterized by a different degree of action properties of either body parts (hands, whole-bodies, and faces) or objects (tools, manipulable objects, and non-manipulable objects). 19 participants participated in the first experiment, in which we collected task-based data with a blocked design to the investigate the selectivity of regions within OTC. To test category-selectivity, we adopted a vector-of-ROI analysis approach (Konkle & Caramazza, 2013). We created and extracted the activations from a series of partially overlapping spheres covering the ventral OTC (from parahippocampal gyrus to inferior temporal gyrus) and lateral OTC (from inferior temporal gyrus to transverse occipital sulcus). 28 participants participated in the second experiment, in which the same stimulus set was presented in an event-related design to characterize the multivariate representations behind the category-selective areas identified in the first experiment; specifically, we computed an action index that captures specific action-related components in OTC representational space. This index was computed by first correlating the patterns of activations between the six categories of objects, and then by subtracting to the correlation between each body-part with tools the correlation between each body-parts and the other inanimate object categories; this results in an index of how each body-part is selectively associated with tools (vs. the other inanimate objects). T-tests were then applied to the results to test for significance.
Results:
In the first experiment, we found that left lateral OTC exhibits a dorsal-posterior to ventral-anterior topographically organized action gradient, with selective and partly overlapping activations for bodies, hands, tools, and manipulable objects, and a selective overlap between hands and tools. Left ventral OTC shows, from medial to lateral, the typical inanimate-animate division with further sub-characterizations: 1) an opposite action gradient in ventro-medial OTC with higher responses to non-manipulable, followed by manipulable and finally tools; 2) distinct responses for hands relative to faces and bodies in ventro-lateral OTC.
In the second experiment, the action index analysis revealed that the action gradient was reflected at the level of multivariate representations only in hand-selective clusters in both left lateral and ventral OTC, i.e., these areas represented hands and tools as being more similar with each other compared to the other object categories.
In the second experiment, the action index analysis revealed that the action gradient was reflected at the level of multivariate representations only in hand-selective clusters in both left lateral and ventral OTC, i.e., these areas represented hands and tools as being more similar with each other compared to the other object categories.
Conclusions:
Our results shed new light on the role of traditionally-defined category-selective areas: hand-selective clusters in visual cortex represent action-related properties of stimuli and their representational profile differentiate from the one of body- or face-selective areas. Altogether, our results show that the object space in hand-selective visual cortex reflects action-related behaviourally-relevant dimensions, and suggest future paths to generate a computational model of this object space (Ratan-Murty et al., 2021).
Modeling and Analysis Methods:
Activation (eg. BOLD task-fMRI) 2
Multivariate Approaches
Perception, Attention and Motor Behavior:
Perception: Visual 1
Keywords:
FUNCTIONAL MRI
Perception
Vision
1|2Indicates the priority used for review
Provide references using author date format
Kanwisher, N. (2010). Functional specificity in the human brain: a window into the functional architecture of the mind. Proceedings of the national academy of sciences, 107(25), 11163-11170.
Konkle, T. (2013). Tripartite organization of the ventral stream by animacy and object size. Journal of Neuroscience, 33(25), 10235-10242.
Peelen, M. V. (2017). Category selectivity in human visual cortex: Beyond visual object recognition. Neuropsychologia, 105, 177-183.
Ratan Murty, N. A. Computational models of category-selective brain regions enable high-throughput tests of selectivity. Nature communications, 12(1), 5540.
Taylor, J. C. (2011). Division of labor between lateral and ventral extrastriate representations of faces, bodies, and objects. Journal of Cognitive Neuroscience, 23(12), 4122-4137.