Rafael Yuste: Is the brain an emergent physical system?

Colloquia

Speaker

Rafael Yuste
Neurotechnology Center, Kavli Institute of Brain Circuits, Columbia University, USA

When

2018/03/22
16:30

Place

DIPC

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Neurotechnology Center, Kavli Institute of Brain Circuits, Columbia University, USA

In physical systems built with many components, emergent properties, such as ferromagnetism, are often generated from the interactions among these units. These emergent properties are, by definition, invisible when observing individual particles, since they depend on large-scale interactions between them. Likewise, the function of the brain has been mostly studied by examining the responses of individual neurons, yet it is probably an emergent property that arises from the coordinated activity of large numbers of neurons in its neural circuits. To capture this emergent level of brain function, we, and others, have developed novel methods to measure and control neural activity across complete neural circuits in experimental animals and human patients. This technological effort, sponsored by the White House as its flagship BRAIN Initiative, is an interdisciplinary project that incorporates into neuroscience many methods and approaches from the physical sciences and nanotechnologies. Data obtained with these new methods could prove to be an invaluable step towards understanding neural computations and pathological brain processes.

In my talk, I will provide examples of how two-photon imaging of the activity of the visual cortex of awake behaving mice reveal indeed the existence of emergent functional states, as neurons are activated together in response to a visual stimulus. These coactive neuronal ensembles resemble the attractors of Hopfield's model of recurrent neural networks, based on the Ising model. Moreover, using two-photon optogenetics, we activate these ensembles and can change the behavior of the animals. Our results are consistent with the hypothesis that these dynamical attractors are the physical implementation of perceptual states or memories.

Prof. Yuste's laboratory
Wikipedia article