The Effect of Thalamic Stimulation on Sleep Oscillations

The thalamus plays a key role in supporting sleep. The thalamus is also increasingly used as a stimulation therapeutic target, but the effect of thalamic stimulation on sleep has not been investigated. We hypothesize that electrical stimulation delivered to the thalamus in humans could both elicit and disrupt sleep oscillations, such as spindles, depending on the timing and location of stimulation. We propose a study to obtain direct evidence in humans of how thalamic stimulation affects sleep. We will test the hypothesis that stimulation during a thalamic sleep spindle disrupts it, while stimulation outside evokes a response resembling a k-complex followed by a spindle. Participants will be patients with refractory epilepsy who have semi-chronically implanted depth electrodes in the thalamus and other brain regions (\~100) as part of the pre-surgical clinical work-up. We will detect spindles and stimulate during or outside oscillations using a real-time closed-loop system that we developed. Simultaneously recording across the brain will comprehensively map the effect and extent of thalamic stimulation on sleep oscillations. This will be the first step to unravel the effect of thalamic stimulation on sleep oscillations and maintenance. This will increase our understanding of the thalamus as a relay of sleep oscillations and could have profound implications to ensure good sleep quality for the increasing number of people implanted with therapeutic stimulation.