Connectionists: World wide VVTNS series (fifth season): Wednesday, June 11, 2025, at 11:00 am EDT| Ulises Pereira Oblinovic Allen Institute
David Hansel
dhansel0 at gmail.com
Sun Jun 8 12:35:39 EDT 2025
[image: VVTNS.png]
https://www.wwtns.online
<https://streaklinks.com/A9c7PbbpKY7PxB6PaAJWGD3-/https%3A%2F%2Fwww.wwtns.online>
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on twitter: wwtns at TheoreticalWide
You are cordially invited to the lecture
Ulises Pereira Oblinovic
Allen Institute
Neural dynamics outside task-coding dimensions
shape decision trajectories
The lecture will be held on zoom on Wednesday, June 11, 2025, at *11:00 am
EDT *
To receive the link: https://www.wwtns.online/register-page
*Abstract: *Decision-making unfolds within high-dimensional neural
population activity, yet traditional analyses focus on low-dimensional
coding subspaces that represent task-relevant variables. Whether these
coding dimensions causally drive decisions or merely reflect them remains
unclear. Here, we investigate the mechanistic role of residual
dimensions—neural activity patterns orthogonal to coding subspaces—in
shaping choice behavior. We developed a recurrent neural network model that
fits large-scale neural recordings and behavior, disentangling coding and
residual subspaces at the single-trial level. Applied to anterior lateral
motor cortex (ALM) and motor thalamus recordings during a delayed response
task, the model reveals that perturbations along residual dimensions—but
not the choice axis—reliably flip decisions, recapitulating a recent
paradoxical effect observed with targeted two-photon optogenetic
manipulations: activity outside the task-coding subspace exerts stronger
causal influence on behavior than perturbations aligned with the choice
axis. These effects arise from transient, high-dimensional feedforward
trajectories shaped by residual dimensions and converging onto discrete
attractor states. Crucially, residual dimensions drive dynamics in coding
dimensions, rather than the reverse. To probe the trial-to-trial impact of
residual activity, we modeled single-trial deviations as low-dimensional
inputs that shift trajectories relative to trial-averaged dynamics. This
framework captures decision variability mechanistically: errors emerge when
fluctuations in residual dimensions steer dynamics toward incorrect
attractors. Extending the model to include thalamocortical loops, we find
that inter-area communication operates primarily through residual—not
choice-selective—pathways. Together, these results challenge the classical
view that decisions are governed by low-dimensional, task-aligned dynamics
alone, revealing a causal and computationally essential role for residual
dimensions in decision-making.
*About VVTNS : Launched as the World Wide Theoretical Neuroscience Seminar
(WWTNS) in November 2020 and renamed in homage to Carl van Vreeswijk in
Memoriam (April 20, 2022), Speakers have the occasion to talk about
theoretical aspects of their work which cannot be discussed in a setting
where the majority of the audience consists of experimentalists. The
seminars, **held on Wednesdays at 11 am ET,** are 45-50 min long followed
by a discussion. The talks are recorded with authorization of the speaker
and are available to everybody on our YouTube channel.*
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"В каждой шутке есть доля шутки"
'Life is good ..' (Carl van Vreeswijk, 1962-2022)
---------------------------------------
David Hansel
Directeur de Recherche au CNRS
Co-Group leader
Cerebral Dynamics Plasticity and Learning lab., CNRS
45 rue des Saints Peres 75270 Paris Cedex 06
Tel (Cell): +33 607508403 - Fax (33).1.49.27.90.62
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