International Workshop in Neurodynamics (ndy’14)

Oscillatory network dynamics are implicated in the functioning of healthy neural circuits and in disease pathology. Manipulating or controlling oscillatory dynamics hence has potential applications both for probing the functional role of oscillations in neural computation and as a therapeutic tool. We have explored the potential of closed-loop optogenetic feedback to manipulate oscillatory network dynamics in hippocampal networks in vitro. We create a feedback loop by using a filtered version of the local field potential recorded in the slice to modulate in real-time the intensity of blue light driving channelrhodopsin expressed in CA3 pyramidal cells. By varying the filtering that transforms the field potential into the feedback signal we can independently and bidirectional control the amplitude and frequency of network oscillations in the slice. This closed loop feedback can suppress oscillatory network dynamics without modifying the average firing rate of individual cells. Control experiments in which we use the stimulus generated in closed-loop on one trial to drive the slice in open-loop fashion on a subsequent trial demonstrate that this suppression is not simply an effect of adding noise to the system, but rather reflects active desynchronisation of the network activity by the feedback signal.