by Prof. Giovanna Citti (University of Bologna)

When: March 23rd, 2023 at 3:00 pm

Where: Sala Seminari at VIMM (Via Orus 2, padova)

Abstract: In this seminar I present a geometric model of the motor cortex, joint work with Mazzetti and Sarti.
The first studies of this area, due to Georgopoulos et alii, proved that neurons are sensible to kinematic
variables, as for example direction of motion, velocity or acceleration. More recently, it has
been experimentally proved by Churchland et alii and by Harpaz et alii that the selectivity of neurons
changes in time, giving rise to selectivity of short trajectories of the hand, called movement
fragments. These fragments can be obtained via a clustering procedure directly on the neural activity.

We consider here the space of the observed kinematic variables: these variables are related by differential
constraints which allow to induce a metric on the space, called sub-Riemannian. We will
recover the movement fragments as integral curves of vector fields defined in the considered structure.
We will use the distance of the space to define a kernel and a kernel PCA, and we will obtain
in the space of kinematic variables the same decomposition obtained on the neural activity. In this
way we characterize a set of variables sufficient to describe this processing in this area.