Max Planck Institute for Dynamics and Self-Organization -- Department for Nonlinear Dynamics and Network Dynamics Group
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Tuesday, 29.05.2012 17 c.t.

Dynamics of an oculomotor integrator revealed by instantaneous optogenetic perturbations

by Dr. Christian Machens
from Neural Theory, Ecole Normale Supérieure, Paris, France

Contact person: Fred Wolf


Ludwig Prandtl lecture hall


The oculomotor integrator (OI) in the hindbrain transforms incoming horizontal eye movement commands into position signals to maintain stable eye fixations after saccades. Previous electrophysiological and pharmacological investigations of the system have shown that neurons in the OI have firing rates that can persist at a continuum of levels, with each level corresponding to a particular fixation. These findings have led to the hypothesis that the OI has a continuum of stable fixed points or stationary states, giving rise to a continuous attractor network. We will explain some of these theoretical concepts and show that they make specific predictions about how the system reacts when subjected to brief perturbations. To test these predictions, we performed optogenetic perturbations in the OI of zebrafish expressing halorhodopsin (or channelrhodopsin). Such light stimulations result in the instantaneous hyperpolarization (or depolarization) of neurons, which in turn results in instantaneous eye movements. We find an overall good agreement between model predictions and the perturbation experiments, although some refinements of the network model are necessary. [joint work with Pedro Goncalves, Aristides Arrenberg, and Herwig Baier.]

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