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Songting Li

Shanghai Jiao Tong University

February 26, 2025

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Timescale localization and signal propagation

in the large-scale cortical network

In the brain, while early sensory areas encode and process external inputs rapidly, higher-association areas are endowed with slow dynamics to benefit information accumulation over time. This property raises the question of why diverse timescales are well localized rather than being mixed up across the cortex, despite high connection density and an abundance of feedback loops that support reliable signal propagation. In this talk, we will address this question by analyzing a large-scale network model of the primate cortex, and we identify a novel dynamical regime termed "interference-free propagation". In this regime, the mean components of the synaptic currents to each downstream area are imbalanced to ensure signals to propagate reliably, while the temporally fluctuating components of the synaptic inputs governed by upstream areas' timescales are largely canceled out, leading to the localization of its own timescale in each downstream area. Our result provides new insights into the operational regime of the cortex, leading to the coexistence of hierarchical timescale localization and reliable signal propagation.

Yonatan Loewenstein

ELSC, The Hebrew University

March 5, 2025

TBA

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Olivier Marre

Institut de la Vision, Paris

March 12, 2025

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TBA

Marcelo Rozenberg

CNRS, Paris

March 19, 2025

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Dynamics of neural motifs realized with a minimal memristive neuro-synaptic unit

The  use of electronic circuits to model neural systems goes back to C. Mead and is present in models, from leaky-integrate-and-fire to Hodking-Huxley. Simulating neural network with analog hardware is attractive: it allows to implement neurocomputations in real time without discretization approximations, it has perfect simulation-time scaling with system size,  and it provides ready-to-deploy neuromorphic circuit for applications. There are implementations in CMOS technology, however, they are complex, require sophisticated fabrication facilities and, most important, suffer from significant device mismatch. In a radically different approach, based on the concept of memristors, we introduce a neuro-synaptic circuit of unprecedented simplicity, with readily available cheap off-the-shelf electronic components, that can quantitatively reproduce textbook theoretical neuron and synaptic current models. Our neuron circuits can avoid the mismatch problem and are easily tuneable at bio-compatible time-scales. We first introduce a voltage-gated conductance bursting neuron model that produces spike traces that bare striking similarity to experimental recordings. We then introduce synaptic current circuits and show the modularity of our method implementing neurocomputing primitives of basic network motifs, including CPGs. With this "theoretical hardware" approach we show: (i) that neuron adaptation and self-excitation can be viewed as a self-consistent dynamical problem; (ii) that a dynamical memory can be minimally implemented with a single recursive spiking neuron; (iii) that an adaptive membrane current reveals a connection between bursting and the driven harmonic oscillator, perhaps pointing to a neural correlate of the pendular limb motion. Finally we discuss the limitation of the approach to networks of mid-size and its potential application for brain-machine-interfaces, robotics and AI.

Eve of Cosyne

 

No Seminar 

March 26, 2025

The following day of Cosyne​

 

No Seminar 

April 2, 2025

James DiCarlo

MIT

April  9, 2025

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Carl van Vreeswijk Memorial Lecture

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TBA

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April 16, 2025

No Seminar

Daniel Durstewitz

Central Institute of

Mental Health, Mannheim

April 23, 2025

TBA

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April 30, 2025

No Seminar

Yohai Bar-Sinai

Tel Aviv University

May 7, 2025

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TBA

Tomoki Fukai

Okinawa Institute of Science and Technology

May 14, 2025

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TBA

Alexei Koulakov

Cold Spring Harbor Laboratory

May 21, 2025

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TBA

Nischal Mainali

May 28, 2025

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TBA

Bing Wen Brunton

University of Washington 

Seattle

June 4, 2025

TBA

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Ulises Pereira Oblinovic

Allen Institute

June 11, 2025

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TBA

Riccardo Zecchina

Bocconi University, Milano

June 18, 2025

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TBA

Andrew Barto

U. Mass

June 25, 2025

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VVTNS Fifth Season Closing Lecture

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