Connections 2009 Biologically inspired stimulation for epilepsy control Supervisor: Berj Bardakjian Presenters: Sinisa Colic and Josh Dian

Problem Epilepsy is a disease that affects millions of people around the world It results from large scale synchronous firing of neuronal action potentials In the most serious cases it can lead to death if untreated -The majority of cases can be successfully treated with medication Cases which do not respond to medication are candidates for surgery which is irreversible and not suitable for all cases Our labs’ focus is to find an effective electrical stimulus control that can deter the onset of a seizure

Motivation It is known that stimulating the seizure focal region prior to the seizure onset can prevent the seizure from occurring all together Our Solution Combine Software and Hardware to model interictal (normal) brain behaviour and use proportional, integrator and differentiator modes to regulate stimulation

Interictal model - Trained radial basis function model (RBF) - Used training set composed of different seizure episodes - filtered out noise such as 60Hz harmonics The RBF successfully captured the chaotic behaviour -verified using lyapunov exponents Actual interictalModeled interictal Recurrent generative mode:

Stimulation control From cable theory it made sense to use proportional, differential and integrating modes to control stimulation Goal of stimulation controller: -System heads on the path to seizure like activity -Seizure prediction algorithm is used to trigger controller initiation -Stimulation is provided by controller until system returns to interictal activity

Hardware implementation The computer hardware used in only capable of limited computation when the real time constraint is present Use field programmable gate arrays (FPGA’s) to enhance computational ability Able to run model based systems in real time FPGA’s are on the roadmap to fabrication which provides a first step on the long term goal of an implantable stimulation capable of detecting and inhibiting seizures

- Currently deep brain stimulation is gaining popularity around the world for treatment of brain disorders -Successful in severe epilepsy, parkinsons, depression and over compulsive behaviour disorders Limitation: -Uses periodic stimuli of approximately 5V which is extremely large considering typical physiological potentials are < 100mV Our Solution: -Uses biologically inspired signals for a more natural control Relation to DBS

Acknowledgements Berj Bardakjian Peter Carlan Eunji Kang CHIR and NSRC for providing the funding to make this project possible