2025 GAC 3

Clarifying and reconciling different perspectives on the structure of the neural code

Meenakshi Khosla, UCSD
Nancy Kanwisher, MIT

Stefano Fusi, Columbia

Nikolaus Kriegeskorte, Columbia

Tatiana Engel, Princeton

Marcus Benna, UCSD

David Klindt, CSHL

Carsen Stringer, HHMI Janeli

Short description

How do brains and artificial networks represent information? The structure of the neural code has been described using diverse frameworks, often creating confusion about their meanings and relationships. Key perspectives include interpretable tuning or category selectivity (vs mixed selectivity), systematic tuning, modularity, clustering, disentangled coding, sparse coding and 

distributed coding (vs localized coding). While some of these concepts emphasize structured, interpretable, or systematic organization, others focus on population-level representations that defy simple partitioning. Single terms (like “modularity”) have been used to refer to multiple fundamentally different concepts, and multiple terms have been used to refer to identical or 

overlapping ideas. This conceptual ambiguity hinders cross-study comparisons, synthesis of theories, and the design of experiments based on a common vocabulary. To add to this confusion, it is also unclear how these concepts interact with or shape the geometry and dimensionality of the activity space.   

We propose a collaborative initiative that aims to clarify these perspectives, develop a consensus terminology, agree on what would count as evidence for each kind of coding scheme, agree on at least one specific data set that embodies each of the coding schemes (including what aspect of those data reveal that coding scheme), understand the conditions under which different forms of coding can coexist or conflict, understand how they relate to underlying properties of the neural code such as its dimensionality and geometry, and seek underlying computational principles that explain why brains and artificial networks code information the way they do.  

GAC kickoff workshop, August 13th at CCN

Schedule of Events

4:00 pm - 5:00 pm    Introduction into the debate (15 mins) 

[Room A0.01]

5:00 pm - 6:30 pm `   Main discussion
[Room A1.02]

5:00 – 5:05 — Welcome & Goals

    Format overview (debates + panel), mention live polling.

5:05 – 5:10 — Key Definitions of topics relevant to debates

    Mixed selectivity, disentangled coding, geometry, tuning, coordinate system, variables etc.

5:10 – 5:25 — Debate 1: Geometry is all you need vs. Tuning matters

    6 min per side, 3 min audience Q&A + poll. (Pro-geometry: Stefano, David,  Pro-tuning: Nancy, Meenakshi)

5:25 – 5:40 — Debate 2: Is there a “right” way to choose variables?

    Short statements (Tatiana, David, Niko, Marcus), 3 min Q&A + poll.

5:40 – 5:45 — Third Issue (Carsen): Are classical coding schemes outdated for primary sensory areas?

    Brief statement + poll.

5:45 – 6:25 — Panel Discussion & Audience Qs

    All speakers respond to themes and poll results.

6:25 – 6:30 — Closing

    Key takeaways + next steps.

Organizers

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