Massive congratulations to lead author @HedgerResearch, and co-authors Thomas Naselaris and @cvnlab .
Read the open-access paper here 👇
bit.ly/VisualBodyMaps

#Neuroscience #BrainMapping #VicariousTouch

This provides a mechanistic basis for everyday vicarious experiences — like flinching when you see someone fall — but the implications go far deeper:
• Social cognition
• Sensory and clinical neuroscience (e.g., ASD)
• Embodied AI & AGI development

The core discovery:
Visual cortex isn’t purely visual — it’s tiled with orderly somatotopic maps, aligned with the maps in primary somatosensory cortex.
Seeing recruits the same body-based computational machinery you use to feel your own body. x.com/HedgerResear...

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. 🧵

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

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

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

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

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

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