Biology subjects

Tal, Z.

Publications and source records attributed to Tal, Z..

4 recordsLinked to original sources

bioRxiv2023

Contentopic mapping in ventral and dorsal association cortex: the topographical organization of manipulable object information

Understanding how object information is neurally organized is fundamental to unravel object recognition1-4. The best-known neural organizational principle of information is topographical mapping of specific dimensions. Such maps have been shown mainly for sensorimotor information within sensorimotor cortices (e.g., retinotopy)5-9. Thus, here we ask whether there are topographic maps - by analogy, contentopic maps - for mid-level object-related dimensions. We used functional magnetic resonance imaging and population receptive field analysis7 to measure tuning of neural populations to selected manipulable object-related dimensions. Here we show maps in dorsal and ventral occipital cortex that code for the score of each object on each target dimension in a linear progression following a particular direction along the cortical surface. Maps for each dimension are distinct, and consistent across individuals. Thus, object information is coded in multiple topographical maps - i.e., contentopic maps. These contentopic maps refer to intermediate level visual and visuomotor representations, and are potentially computed from the grouping of lower-level information through non-linear transformation following gestalt principles4,10. This shows that topography is a widespread and non-incidental strategy for the organization of information in the brain that leads to greatly reduced connectivity-related metabolic costs and fast and efficient readouts of information for stimuli discrimination11,12.

neuroscience↗

bioRxiv2023

The neural organization of visual information in the auditory cortex of the congenitally deaf

Neuroplasticity is the ability of the human brain to reorganize and modify its activity throughout life. In congenital deafness, sensory-deprived cortex can be recruited to represent sensory information belonging to other modalities, a process known as cross-modal plasticity. Previous studies have indicated that the auditory cortex of congenitally deaf, but not of hearing individuals, is recruited during visual tasks. However, it is not clear to what extent, and how, these cross-modal responses in the deprived auditory cortex represent low-level visual spatial information or map the visual field. Here, we addressed this question directly in an fMRI case-study, aiming to map retinotopic features in the auditory cortex. Two congenitally deaf and one hearing participant went through a conventional retinotopy fMRI experiment with visual stimuli designed to map the visual system. Using population receptive field (pRF) modelling, we revealed retinotopic-related responses in the auditory cortex of the deaf, but not in the hearing. These responses, that were mostly lateralized to the right hemisphere, represented the contralateral visual field, and were characterized by large receptive fields, centred to near foveal areas. Interestingly, we found that these responses to visual stimuli predominantly reflected negative BOLD signals in the auditory cortex of the deaf, suggesting that visual information might be represented through cross-modal deactivation signals.

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↗

bioRxiv2022

The way of the light: how visual information reaches the auditory cortex in congenitally deaf adults

Human and animal studies on cross-modal plasticity under congenital deafness suggest that early auditory cortex plays a significant role in the processing of visual information when congenitally deprived from its typical (auditory) input. However, the pathway by which early auditory cortex is fed with visual information is still understudied. Here we focused on addressing how visual information reaches the auditory cortex under congenital deafness. We put forth a mechanistic model that proposes that different corticocortical and subcortical connections play a central role in rerouting visual information to the early auditory cortex of congenitally deaf individuals. Specifically, we show, using Representational Connectivity Analysis (RCA) and Dynamic Causal Modeling (DCM), that connections from the right superior colliculus to the right inferior colliculus, as well as connections from right early visual cortical regions to the right early auditory cortex play a role in rerouting visual information to early auditory cortex in congenitally deaf individuals. These findings shed light on how visual information reaches the early auditory cortex of deaf individuals - specifically, they suggest that neuroplasticity reshapes subcortical connections in order to re-route visual information to the auditory stream.

neuroscience↗