Tomas Knapen
@tknapen.bsky.social
Computational Neuroimaging Researcher based in Amsterdam
And people sampling the videos with their eyes allows them to shape their own brain responses. This will likely generate an additional level of “individuality” to brain responses, lowering ISC
December 11, 2024 at 3:46 PM
And people sampling the videos with their eyes allows them to shape their own brain responses. This will likely generate an additional level of “individuality” to brain responses, lowering ISC
Our results indicate the brain uses aligned, 'multiplexed' topographic maps to structure connections between vision and somatosensation. The computational machinery classically attributed to the somatosensory system is embedded within/aligned with that of the "visual" system. 🧵
December 3, 2024 at 3:13 PM
Our results indicate the brain uses aligned, 'multiplexed' topographic maps to structure connections between vision and somatosensation. The computational machinery classically attributed to the somatosensory system is embedded within/aligned with that of the "visual" system. 🧵
These findings complement recent work indicating that dorsolateral visual cortex is a fundamentally multi-sensory part of the brain whose role extends beyond passive visual analysis to encompass semantic and bodily information relevant to interactions with the world. 20/n
December 3, 2024 at 3:13 PM
These findings complement recent work indicating that dorsolateral visual cortex is a fundamentally multi-sensory part of the brain whose role extends beyond passive visual analysis to encompass semantic and bodily information relevant to interactions with the world. 20/n
These encoding model fits revealed a new map of visual body-part selectivity, which overlapped with somatotopic tuning across the FBA, EBA and, strikingly, the visual word form area (VWFA). 19/n
December 3, 2024 at 3:13 PM
These encoding model fits revealed a new map of visual body-part selectivity, which overlapped with somatotopic tuning across the FBA, EBA and, strikingly, the visual word form area (VWFA). 19/n
To address this, we combined the Natural Scenes Dataset with a pose-detection algorithm fit a body-part tuning encoding model. This allowed us to generate a map of visual body part preference, organised along a similar toe-to-tongue axis as the somatotopic connectivity maps. 18/n
December 3, 2024 at 3:13 PM
To address this, we combined the Natural Scenes Dataset with a pose-detection algorithm fit a body-part tuning encoding model. This allowed us to generate a map of visual body part preference, organised along a similar toe-to-tongue axis as the somatotopic connectivity maps. 18/n
Much of visual cortex is body-part selective. If this tuning relates to our somatotopic connectivity, we should also be able to predict visual body part selectivity from somatotopic tuning and reveal multi-modal body-referenced alignment playing out at more semantic levels. 17/n
December 3, 2024 at 3:13 PM
Much of visual cortex is body-part selective. If this tuning relates to our somatotopic connectivity, we should also be able to predict visual body part selectivity from somatotopic tuning and reveal multi-modal body-referenced alignment playing out at more semantic levels. 17/n
We did indeed find evidence for an alignment between visual field tuning and body part tuning beyond that expected by chance. We found this mostly dorsally and in the superior portion of EBA. 16/n
December 3, 2024 at 3:13 PM
We did indeed find evidence for an alignment between visual field tuning and body part tuning beyond that expected by chance. We found this mostly dorsally and in the superior portion of EBA. 16/n
But do these bodily maps predict anything about visual function? For instance, could lower body part tuning (e.g. toes) predict lower visual field tuning? Such an alignment might facilitate interactions with the environment. 15/n
December 3, 2024 at 3:13 PM
But do these bodily maps predict anything about visual function? For instance, could lower body part tuning (e.g. toes) predict lower visual field tuning? Such an alignment might facilitate interactions with the environment. 15/n
Yes! Throughout dorsolateral visual cortex, we see several body-part gradients separated by reversals. These maps were consistent across hemispheres and subject splits. 14/n
December 3, 2024 at 3:13 PM
Yes! Throughout dorsolateral visual cortex, we see several body-part gradients separated by reversals. These maps were consistent across hemispheres and subject splits. 14/n
But what about the body part tuning of these somatotopic activations? Do these dorsolateral regions exhibit orderly gradients, as found in 'core' somatosensory regions around the central sulcus? The answer is... 13/n
December 3, 2024 at 3:13 PM
But what about the body part tuning of these somatotopic activations? Do these dorsolateral regions exhibit orderly gradients, as found in 'core' somatosensory regions around the central sulcus? The answer is... 13/n
We then repeated our somatosensory connectivity analyses separately on a movie section involving human agents and another without any humans. This demonstrated that somatotopic responses are not generic, but driven by movie content, specifically that featuring human action. 12/n
December 3, 2024 at 3:13 PM
We then repeated our somatosensory connectivity analyses separately on a movie section involving human agents and another without any humans. This demonstrated that somatotopic responses are not generic, but driven by movie content, specifically that featuring human action. 12/n
Our analysis allows us to contrast somatotopic and retinotopic explained variance. All dorsolateral (but not ventral!) visual regions were characterised by multimodal topographic connectivity. These regions care as much or more about the body as they do the visual scene! 11/n
December 3, 2024 at 3:13 PM
Our analysis allows us to contrast somatotopic and retinotopic explained variance. All dorsolateral (but not ventral!) visual regions were characterised by multimodal topographic connectivity. These regions care as much or more about the body as they do the visual scene! 11/n
We find that movie watching led to increased somatotopic connectivity in the somatosensory network outlined above. But strikingly, we now also find that dorsolateral visual cortex has structured connectivity with S1. Look at that red band across visual cortex! 10/n
December 3, 2024 at 3:13 PM
We find that movie watching led to increased somatotopic connectivity in the somatosensory network outlined above. But strikingly, we now also find that dorsolateral visual cortex has structured connectivity with S1. Look at that red band across visual cortex! 10/n
So, we turned to the HCP movie watching experiment. This dataset allows us to investigate the relation of somatosensory connectivity to naturalistic visual experiences, where mental content is yoked to a visual stimulus. 9/n
December 3, 2024 at 3:13 PM
So, we turned to the HCP movie watching experiment. This dataset allows us to investigate the relation of somatosensory connectivity to naturalistic visual experiences, where mental content is yoked to a visual stimulus. 9/n
So, during resting state, endogenous activations throughout frontal, parietal, and insular cortex resonate along scaffolding provided by the somatotopic structure of bodily sensations. But how this resonance relates to mental content in resting state is unclear... 8/n
December 3, 2024 at 3:13 PM
So, during resting state, endogenous activations throughout frontal, parietal, and insular cortex resonate along scaffolding provided by the somatotopic structure of bodily sensations. But how this resonance relates to mental content in resting state is unclear... 8/n
Body part tuning revealed multiple somatotopic gradients and body-part tuning biases that are typically only revealed by exogenous stimulation (e.g. brushing people). Critically, we show that these same detailed principles can be revealed in the absence of sensory input! 7/n
December 3, 2024 at 3:13 PM
Body part tuning revealed multiple somatotopic gradients and body-part tuning biases that are typically only revealed by exogenous stimulation (e.g. brushing people). Critically, we show that these same detailed principles can be revealed in the absence of sensory input! 7/n
Since this method uses one part of the brain to explain another, we can fit these models to any data - even with no stimulus! Analysing 7T resting state data from the HCP, we found signals in a large cortical network were predicted by somatotopic connectivity with S1. 6/n
December 3, 2024 at 3:13 PM
Since this method uses one part of the brain to explain another, we can fit these models to any data - even with no stimulus! Analysing 7T resting state data from the HCP, we found signals in a large cortical network were predicted by somatotopic connectivity with S1. 6/n
This allows us to 'project' the visual field or body part tuning of V1 and S1 onto the rest of the brain. We’re performing connectivity-derived retinotopic and somatotopic mapping, which allows us to find higher-level sensory maps throughout the brain. 5/n
December 3, 2024 at 3:13 PM
This allows us to 'project' the visual field or body part tuning of V1 and S1 onto the rest of the brain. We’re performing connectivity-derived retinotopic and somatotopic mapping, which allows us to find higher-level sensory maps throughout the brain. 5/n
Our computational model of functional connectivity explains target voxels’ timecourses as 'connective fields' located on the surfaces of both V1 and S1. Due to their specific locations on our primary sensory cortices, connective fields inherit visual and somatotopic tuning. 4/n
December 3, 2024 at 3:13 PM
Our computational model of functional connectivity explains target voxels’ timecourses as 'connective fields' located on the surfaces of both V1 and S1. Due to their specific locations on our primary sensory cortices, connective fields inherit visual and somatotopic tuning. 4/n
These findings raise the question how the brain connects the computational machinery of vision and touch. Here, we developed a model for measuring joint visual and somatosensory tuning throughout the brain and applied it to resting state and movie watching data. 3/n
December 3, 2024 at 3:13 PM
These findings raise the question how the brain connects the computational machinery of vision and touch. Here, we developed a model for measuring joint visual and somatosensory tuning throughout the brain and applied it to resting state and movie watching data. 3/n
When seeing bodily experiences, our brain responds 'as if' it simulates the observed tactile experience as our own. We know that e.g. viewing fingers being touched can activate finger-selective regions of primary somatosensory cortex (S1) (tinyurl.com/vissom3b) 2/n
December 3, 2024 at 3:13 PM
When seeing bodily experiences, our brain responds 'as if' it simulates the observed tactile experience as our own. We know that e.g. viewing fingers being touched can activate finger-selective regions of primary somatosensory cortex (S1) (tinyurl.com/vissom3b) 2/n