title: Closed-loop feedback control and bifurcation analysis of epileptiform activity via optogenetic stimulation in a mathematical model of human cortex.
abstract: Optogenetics provides a method of neuron stimulation that has high spatial, temporal, and cell-type specificity. Here we present a model of optogenetic feedback control that targets the inhibitory population, which expresses light-sensitive channelrhodopsin-2 channels, in a mean-field model of undifferentiated cortex that is driven to seizures. The inhibitory population is illuminated with an intensity that is a function of electrode measurements obtained via the cortical model. We test the efficacy of this control method on seizurelike activity observed in two parameter spaces of the cortical model that most closely correspond to seizures observed in patients. We also compare the effect of closed-loop and open-loop control on seizurelike activity using a less-complicated ordinary differential equation model of the undifferentiated cortex in parameter space. Seizurelike activity is successfully suppressed in both parameter planes using optimal illumination intensities less likely to have adverse effects on cortical tissue.
authors: Department of Mechanical Engineering, University of California, Berkeley, California 94720-1740, USA.
authors: Prashanth
authors: P
authors: Selvaraj
authors: Waikato Clinical School, University of Auckland, Hamilton, New Zealand.
authors: Jamie W
authors: JW
authors: Sleigh
authors: Departments of Neurology and Radiology and Biomedical Imaging, University of California, San Francisco, California 94143, USA.
authors: Heidi E
authors: HE
authors: Kirsch
authors: Department of Mechanical Engineering, University of California, Berkeley, California 94720-1740, USA.|Center for Neural Engineering and Prostheses, University of California, Berkeley, California 94720-3370, USA.
authors: Andrew J
authors: AJ
authors: Szeri
mesh_terms: D000200:Action Potentials / Q000502:physiology; D002540:Cerebral Cortex / Q000503:physiopathology*; D025461:Feedback, Physiological / Q000502:physiology*; D006801:Humans; D008959:Models, Neurological; D009433:Neural Inhibition / Q000502:physiology; D009474:Neurons / Q000502:physiology; D062308:Optogenetics / Q000379:methods*; D010775:Photic Stimulation / Q000379:methods; D012243:Rhodopsin / Q000378:metabolism; D012640:Seizures / Q000503:physiopathology*; D013269:Stochastic Processes
chemical_list: D012243:Rhodopsin