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Modelling and Control of Deep Brain stimulation
in Parkinson's Disease

(In preparation...)


Control of Epidural Electrical Stimulation to Optimize
Spinal Neuroprosthetic Systems

Background. Severe lesions of the spinal cord (SC) damage the neural pathways at the level of the injury and interrupt most supraspinal control. This loss of connectivity abolishes motor function and leads to paralysis of the limbs. However the spinal circuitry itself is an active participant in the process, often referred to as `central pattern generator': even in the absence of brain input, pools of motor neurons in the lumbosacral SC are able to exploit specific proprioceptive signals from the legs and to generate coordinated rhythmic movements. After the injury, the SC retains this capacity but lacks the level of excitation required for this control to be manifested.

Rationale. This neural circuitry may be activated using invasive neuroprosthetic systems. Electrical pulses applied epidurally in the dorsal face of the SC (commonly referred to as EES) can modulate the excitability of these circuits, and elicit stepping-like movements in spinal rats on a treadmill. Interestingly, the stepping patterns observed vary when changing the stimulus parameters (i.e., voltage, pulse duration and amplitude). This framework lends itself to the development of stimulation strategies that would allow to take full advantage of EES.

Recent experimental setups employ indeed mutliple electrodes to increase the specificity, and constant (tonic) stimulation that is manually tuned offline for the different electrodes based on visual inspection. However, there are few guidelines available to guide the selection of the appropriate stimulus parameters; from an experimental point of view, their tuning is largely an ad hoc manual process that requires of extensive human expertise in order to comprehend the highly complex (and often unknown) dynamics of gait induced by EES. Such task becomes impractical when increasing the number ofstimulation sites, as the combination of possible stimulation patterns quickly `explodes'.

Goal. We are pursuing the development of automatic control apporaches that could instead optimize the stimulation paradigm online, and account for the specific biomechanical state of the system, thereby inducing more natural and repeatable movements, and potentially leading to improved rehabilitation results.


Dr. Jack DiGiovanna
ETH Zurich. Switzerland

Dr. Dario Izzo.
European Space Agency, Advanced Concepts Team. Netherlands

Dr. Dominique Martinez
CNRS / LORIA. France

Dr. Gordon Cheng
Technical University Munich. Germany (formerly at ATR International)

Juxi Leitner
IDSIA. Switzerland

Dr. Christos Ampatzis
European Research Council. Belgium (formerly at ESA ACT)

Dr. Joshua G. Hale
Cyberdine. Japan (formerly at ATR International)

Prof. Sethu Vijayakumar
Edinburgh University. UK

Ian Saunders
Edinburgh University. UK

Eduardo Martin Moraud 2016. All rights reserved