Lenny van Dyck

Category selectivity vs. behavioral relevance in visual cortex? 👁️🧠
@levandyck.bsky.social and I really enjoyed diving into this piece and appreciated the authors’ thoughtful response. We're curious to see how the field moves forward from here! ➡️

What behavioral relevance is (not) We are thankful for the thoughtful commentaries of our colleagues. In our discussion article, we argued for a course correction to how the field approaches the organization of visual function in oc...

Our reply to 11 commentaries on our article ("Rethinking category-selectivity in human visual cortex") is out in Cognitive Neuroscience! Thanks to @susanwardle.bsky.social @maryamvaziri.bsky.social Dwight Kravitz @cibaker.bsky.social and all who contributed! 1/x www.tandfonline.com/doi/full/10....

To summarize:

Both models and cortex show partially integrated face and body representations, which converge along the visual hierarchy. This may strike a balance between segregation and integration, building part-based representations that support the full range of person perception. 🧠

9/9

Finally, we examined how DNNs integrate faces and bodies:

DNN responses to whole persons approximated the sum of their responses to isolated faces and bodies, suggesting part-based rather than holistic integration.

8/n

Back in DNNs, we tested whether mixed selectivity is functionally relevant:

We trained a DNN on different person perception tasks and lesioned each unit type. Lesioning mixed-selective units led to deficits across tasks, confirming these units actively support person perception.

7/n

While face- and body-selective units explained substantial unique variance in their corresponding regions, they mainly explained shared variance.

Crucially, this shared component increased from posterior to anterior regions, suggesting that integration grows along the cortical hierarchy.

6/n

Let’s now link this to visual cortex:

Mixed-selective units best predicted activity in both face- and body-selective regions, suggesting that they encode more integrated person information than generally assumed. 🪢

5/n

Let’s first look at computational models of visual cortex:

Diverse DNNs developed distinct face- and body-selective units, but also mixed-selective units responding to both categories. This suggests that face-body integration naturally arises from learning to recognize whole persons. 🕺

4/n

So, here we ...
1️⃣ Used a functional localizer to test whether DNNs develop distinct and/or shared tuning for faces and bodies.
2️⃣ Applied fMRI encoding models to map DNN representations onto visual cortex.
3️⃣ Closely examined DNN representations to generate hypotheses about face-body integration.

3/n

The brain has specialized regions for faces and bodies. However, in the real world, they usually appear together as whole persons.

Whether and how visual cortex integrates face and body representations remains largely unclear. 🤔

2/n

How segregated vs. integrated are face and body representations in human visual cortex?

In this new preprint with @kathadobs.bsky.social, we use DNNs and fMRI to find out.

www.biorxiv.org/content/10.6...
#neuroskyence

🧵 1/n

🚨 Jewelia’s new preprint! We report the first pRF mapping in teens + reveal functional fingerprints of category regions in high-level visual cortex. www.biorxiv.org/content/10.6...

🔥 We have a new preprint! 🔥
It's really nice, I recommend reading it

Here's a summary question: Can FFA activation predict RT to faces?

⏬ Check out the answer below ⏬

@hansopdebeeck.bsky.social
www.biorxiv.org/content/10.6...

🧨 Preprint alert
Is it easier to find a ball than a shoe? The answer lies in how variable we think these objects are in the real-world. www.biorxiv.org/content/10.6...

w/ the amazing @dkaiserlab.bsky.social & @luchunyeh.bsky.social 🦄

🧵1/8

1/7 Can infants recognise the world around them? 👶🧠 As part of the FOUNDCOG project, we scanned 134 awake infants using fMRI. Published today in Nature Neuroscience, our research reveals 2-month-old infants already possess complex visual representations in VVC that align with DNNs.

High-dimensional structure underlying individual differences in naturalistic visual experience Han and Bonner reveal that individual visual experience arises from high-dimensional neural geometry distributed across multiple representational scales. By characterizing the full dimensional spectru...

Human visual cortex representations may be much higher-dimensional than earlier work suggested, but are these higher dimensions of cortical activity actually relevant to behavior? Our new paper tackles this by studying how different people experience the same movies. 🧵 www.cell.com/current-biol...

Federal agents with weapons drawn, moments before murdering American citizens on the streets of Minneapolis at the dawn of 2026.

What should academics be doing right now?

I have been writing up some thoughts on what the research says about effective action, and what universities specifically can do.

davidbau.github.io/poetsandnurs...

It's on GitHub. Suggestions and pull requests welcome.
github.com/davidbau/poe...

Now out in @cp-trendscognsci.bsky.social: our short response to @neurosteven.bsky.social & Edward de Haan's recent paper on the binding problem. We argue that the binding problem arises because of tradeoffs faced by any information processing system, including the brain and DNNs. shorturl.at/RGXzt

Our new paper in @sfnjournals.bsky.social shows different neural systems for integrating views into places--PPA integrates views *of* a location (e.g., views of a landmark), while RSC integrates views *from* a location (e.g., views of a panorama). Work by the bluesky-less Linfeng Tony Han.

Now in press at Nature Communications!
www.nature.com/articles/s41...
Check it out if you are interested in category selectivity, the organization of visual cortex, and topographic models!

Dimensionality reduction may be the wrong approach to understanding neural representations. Our new paper shows that across human visual cortex, dimensionality is unbounded and scales with dataset size—we show this across nearly four orders of magnitude. journals.plos.org/ploscompbiol...

New Correspondence with @davidpoeppel.bsky.social in Nat Rev Neurosci. www.nature.com/articles/s41...

Here, we critique a recent paper by Rosas et al. We argue that "Bottom-up" and "Top-down" neuroscience have various meanings in the literature.

PDF: rdcu.be/eSKYI

Investigating individual-specific topographic organization has traditionally been a resource-intensive and time-consuming process. But what if we could map visual cortex organization in thousands of brains? Here we offer the community with a toolbox that can do just that! tinyurl.com/deepretinotopy

Y’all are reading this paper in the wrong way.

We love to trash dominant hypothesis, but we need to look for evidence against the manifold hypothesis elsewhere:

This elegant work doesn't show neural dynamics are high D, nor that we should stop using PCA

It’s quite the opposite!

(thread)

Our target discussion article out in Cognitive Neuroscience! It will be followed by peer commentary and our responses. If you would like to write a commentary, please reach out to the journal! 1/18 www.tandfonline.com/doi/full/10.... @cibaker.bsky.social @susanwardle.bsky.social

Really looking forward to #CCN2025!

On Tuesday, I'm presenting new work with @kathadobs.bsky.social on segregated vs. integrated face & body processing in visual cortex 😊🧍🧠

Using DNNs & fMRI, we test competing hypotheses, finding both distinct & shared selectivity.

Come by Poster A64 for more.

Very much looking forward to #CCN2025! Would love to see you at our lab's talks and posters, and meet me at the panel discussion in the Algonauts session on Wednesday!

Investigating action topography in visual cortex and deep artificial neural networks High-level visual cortex contains category-selective areas embedded within larger-scale topographic maps like animacy and real-world size. Here, we propose action as a key organizing factor shaping vi...

New preprint out! We propose that action is a key dimension shaping the topographic organization of object categories in lateral occipitotemporal cortex (LOTC)—and test whether standard and topographic neural networks capture this pattern. A thread:

www.biorxiv.org/content/10.1...

🧵 1/n

YouTube video by McGovern Institute Things and Stuff: How the brain distinguishes oozing fluids from solid objects

Super excited to share our new article: “Dissociable cortical regions represent things and stuff in the human brain” with @nancykanwisher.bsky.social, @rtpramod.bsky.social and @joshtenenbaum.bsky.social

Video abstract: www.youtube.com/watch?v=B0XR...

Paper: authors.elsevier.com/a/1lWxv3QW8S...

Many-Two-One: Diverse Representations Across Visual Pathways Emerge from A Single Objective How the human brain supports diverse behaviours has been debated for decades. The canonical view divides visual processing into distinct "what" and "where/how" streams – however, their origin and inde...

🧠 NEW PREPRINT
Many-Two-One: Diverse Representations Across Visual Pathways Emerge from A Single Objective
www.biorxiv.org/content/10.1...