brain pacemakers – developing closed loop stimulation sobell department of motor neuroscience and...
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Brain pacemakers – developing closed loop stimulationSobell Department of Motor Neuroscience and Movement Disorders,
UCL Institute of Neurology, London, UKNuffield Department of Clinical Neurology, University of Oxford, Oxford, UK
This study was funded by the Wellcome Trust, MRC, NIHR & Rosetrees FoundationFor further details please contact Dr. Simon Little ([email protected]) or Prof. Peter Brown ([email protected])
Channels are from bottom to top: raw brain signal, signal filtered to isolate the pathological component, running average of pathological activity amplitude with triggering threshold superimposed, stimulation trigger signal and stimulation train. Boxed area shows a burst of pathological oscillations.
Brain waves recorded by the depth electrode are amplified and displayed on computer screen. The signal is filtered to only leave the pathological 20 Hz component and the amplitude of pathological activity is computed. A threshold is set that triggers stimulation when pathological activity is detected. Stimulation terminates when pathological brain waves disappear again.
Experimental closed-loop brain stimulation system
Sample section of closed loop mode recordings
• Closed loop stimulation was significantly more effective than time matched random stimulation.
• It was on only 42% of the time making it possible to save battery power in implanted devices.
• With time pathological activity appeared less frequently indicating that the brain learned to suppress it when stimulated adaptively.
• Work is now ongoing to test whether this is effective for all symptoms of Parkinson’s eg. walking and balance and also whether it reduces side-effects like speech disturbance.
motor STN
GPi
Vim
Zona incerta
PPN
Dystonia
Essentialtremor
Anterior capsule
Nucleus accumbens
OCD
Alcoholdependence
Cg25Depression
GPi
Cm/PF thalamic nuclei
Tourette
VPL
VPM
Chronicpain
Hypothalamus
Occipital nerve
Clusterheadaches
limbic STN
NBM
PDdementia
PD
Brain pacemakers are a novel way to treat a range of neurological and psychiatric disorders
Electrodes are placed by a neurosurgeon in a precisely targeted deep brain area and connected to a stimulator in the chest. Different deep brain targets are used for different diseases. New targets and indications are constantly being tested.
Pathological brain waves in Parkinson’s disease
When examining brain waves (top) recorded from the deep brain nucleus where stimulation can alleviate the symptoms of Parkinson’s disease, the researchers found pathological periodic waves (oscillations) with frequency of about 15-20 Hz (cycles/second). These waves’ appearance coincides with the patient’s difficulties in movement. When doing spectral analysis of brain activity the pathological waves appear as a sharp peak (bottom left). Therapeutic stimulation of the nucleus makes the pathological oscillations go away as the patients start feeling better. Until now only constant stimulation has been used. Our work is aimed at using the pathological waves to trigger stimulation only when needed.
Results and impact