TABLE 4.

Biomarkers Classified by Control Subtypes

Control mode/class	Specific examples of biomarkers/devices	Description
Simple continuous	Open Loop DBS	All adjustments via clinician/direct patient observation
Intermittent	ANT DBS	Scheduled on preset timing, therefore no biomarkers used (exception: VNS and heart rate as biomarker preceding seizure event)
	VNS
Responsive/triggered	Neuropace	Predetermined output in response to threshold
	DBS for tourette	Conditional output in response to motor cortex patterned responses
	DBS for essential tremor	Output in response to motor cortex movement initiation signal
Adaptive	DBS for Parkinson disease (eg, PC + S and RC + S)	Currently external; response tailored to continuous input signal.
		Includes motor cortex/STN coherence (eg, PAC), spontaneous beta band, stimulation-evoked responses.
Closed Loop	Braingate system	Multiple inputs (∼100 channels) process to form contingent output
	Other custom systems