Work in progress — pages and figures are still being written.

Alicia Zeng

All research

Closed loop

Deep brain stimulation is set in a clinic over an afternoon and then runs unchanged for months, in a disease whose symptoms move over the course of a day. Closing that gap means letting the stimulator respond to the person, and that has to start with measuring what the person is doing.

A clinic visit cannot supply that measurement. The behaviour worth responding to happens at home across hours, and the neural signal you would drive the stimulator from is itself partly a consequence of the stimulation already being delivered. Recording is therefore the first problem: implanted electrodes, wearables and video running at once in somebody’s house, and synchronised closely enough that they can be compared.

Once they can, the question is whether behaviour predicts the neural signal well enough to be worth decoding from.

Parkinson’s, measured at home–

Participants with bidirectional neurostimulators were recorded at home while working through a standardised motor battery. The implant returned local field potentials from the subthalamic nucleus and electrocorticography from precentral and postcentral cortex; accelerometers on both wrists and video pose estimation recorded what the person was doing. At that resolution behaviour predicts neural power well enough to fit encoding models in that direction, and how well depends on how finely behaviour is described: the full acceleration spectrogram and the task labels do considerably better than mean acceleration.

The video plays one session through at the clinically preferred amplitude. The upper two panels are the cortical contact pairs; the lower one is the wrist on the side that hemisphere controls. Bright columns in the wrist are the participant moving, and the cortical changes alongside them are what the encoding models are fit to. The two subthalamic channels carry much less of this and are not shown. With Simon Little (UCSF) and Jeffrey Herron (UW).