[CTN] CTN seminar: Dr. Paul Cisek, 3:30 Nov 20, PAS 2464

[Bryan Tripp]

Hi everyone,

Just a reminder about the CTN seminar tomorrow. Paul Cisek will talk about
motor-cortical correlates of evolving decisions.

Bryan


On Thu, Nov 12, 2015 at 10:14 PM, Bryan Tripp <bptripp at gmail.com> wrote:

> Hi everyone,
>
> The next CTN seminar will be next Friday (not Tuesday!) the 20th at 3:30,
> in PAS 2464. Paul Cisek is visiting from University of Montreal. The title
> and abstract follow.
>
> Please let me know if you would like to meet with Paul and/or join us for
> dinner after the talk.
>
> Regards,
> Bryan
>
> The neural dynamics of dynamic decisions
>
> During natural behavior, animals must continuously make decisions in a
> rapidly changing environment. Recent studies suggest that in such
> conditions, the brain simultaneously represents multiple potential actions
> that compete against each other within the same sensorimotor control
> circuits involved in execution. Here, I present analyses of neural spiking
> activity recorded from the cerebral cortex of monkeys, while they decided
> between two reaching movements based on a changing stimulus indicating
> which is more likely to be rewarded. We represent the state of the system
> as an evolving trajectory in a very high-dimensional space where each axis
> corresponds to the activity of one neuron, and use dimensionality reduction
> to project this to a 9-dimensional space capturing most of the variance in
> the data. We find that during the process of deliberation, the neural state
> evolves upon a roughly two-dimensional “decision manifold” defined by
> orthogonal components related to sensory evidence and the growing urge to
> respond. The moment of commitment occurs when the neural state falls off
> the edge of this manifold into one of two orthogonal attractors that lead
> to the initiation of the movements. We find qualitatively different
> decision manifolds in different brain regions. For example, the manifold in
> premotor cortex is significantly curved while in primary motor cortex it is
> remarkably linear. We conjecture that the premotor cortex implements a
> non-linear recurrent attractor system in which the decision is made, and
> this is read-out by the primary motor cortex to initiate the chosen action.
>
>
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