title: Optogenetic perturbations reveal the dynamics of an oculomotor integrator.
abstract: Many neural systems can store short-term information in persistently firing neurons. Such persistent activity is believed to be maintained by recurrent feedback among neurons. This hypothesis has been fleshed out in detail for the oculomotor integrator (OI) for which the so-called "line attractor" network model can explain a large set of observations. Here we show that there is a plethora of such models, distinguished by the relative strength of recurrent excitation and inhibition. In each model, the firing rates of the neurons relax toward the persistent activity states. The dynamics of relaxation can be quite different, however, and depend on the levels of recurrent excitation and inhibition. To identify the correct model, we directly measure these relaxation dynamics by performing optogenetic perturbations in the OI of zebrafish expressing halorhodopsin or channelrhodopsin. We show that instantaneous, inhibitory stimulations of the OI lead to persistent, centripetal eye position changes ipsilateral to the stimulation. Excitatory stimulations similarly cause centripetal eye position changes, yet only contralateral to the stimulation. These results show that the dynamics of the OI are organized around a central attractor state-the null position of the eyes-which stabilizes the system against random perturbations. Our results pose new constraints on the circuit connectivity of the system and provide new insights into the mechanisms underlying persistent activity.
authors.affiliation: Group for Neural Theory, Departement d'Etudes Cognitives, INSERM U960, École Normale Supérieure Paris, France ; Champalimaud Neuroscience Program, Centro Champalimaud - Champalimaud Centre for the Unknown Lisbon, Portugal ; Gatsby Computational Neuroscience Unit, University College London London, UK.
authors.forename: Pedro J
authors.initials: PJ
authors.lastname: Gonçalves
authors.affiliation: Neuroscience Program, Department of Physiology, University of California San Francisco San Francisco, CA, USA ; Faculty of Biology, Center for Biological Signaling Studies, University of Freiburg Freiburg, Germany.
authors.forename: Aristides B
authors.initials: AB
authors.lastname: Arrenberg
authors.affiliation: Faculty of Biology, Center for Biological Signaling Studies, University of Freiburg Freiburg, Germany.
authors.forename: Bastian
authors.initials: B
authors.lastname: Hablitzel
authors.affiliation: Neuroscience Program, Department of Physiology, University of California San Francisco San Francisco, CA, USA ; Max Planck Institute of Neurobiology Martinsried, Germany.
authors.forename: Herwig
authors.initials: H
authors.lastname: Baier
authors.affiliation: Group for Neural Theory, Departement d'Etudes Cognitives, INSERM U960, École Normale Supérieure Paris, France ; Champalimaud Neuroscience Program, Centro Champalimaud - Champalimaud Centre for the Unknown Lisbon, Portugal.
authors.forename: Christian K
authors.initials: CK
authors.lastname: Machens
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D005133:Eye Movements / Q000502:physiology*; D008959:Models, Neurological; D009474:Neurons / Q000502:physiology*; D009802:Oculomotor Nerve / Q000502:physiology*; D062308:Optogenetics; D015027:Zebrafish
keywords: model; network dynamics; neural integrator; oculomotor system; optogenetics; zebrafish