programmable stimulus generator and multielectrode array to investigate new electrical stimulation protocols for relief from seizure-like activity

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Studies of epilepsy have characterized the electrical activity associated with the onset of seizures in mammals and can be suppressed via the application of an electrical stimulus. It has been shown that the suppression of seizure-like activity varies with the stimulus frequency; at low frequencies the suppression is slow to take effect, but the effect is long-lasting after the stimulus is removed whereas at higher frequencies relief is immediate but does not last as long. This collaboration has already confirmed such data.    The equipment requested in this grant will initially be used to investigate the response of epileptic seizure-like activity in rat hippocampal tissue to a mixed-frequency electrical stimulus. By mixing more than one frequency into the electrical stimulus signal it is anticipated that the benefits of both high and low frequencies may be observed. This is an important study as "Although stimulation for uncontrolled epilepsy with electrodes implanted in the brain itself has been done for many years, the initial claims for therapeutic success have not been confirmed by the very few clinical studies that have been done so far. The best structures to stimulate and the most effective stimuli to use are unknown." ("The Lancet: Neurology", Vol. 3, 2004, pp.111-118). This investigation will take steps to understand the processes behind the suppression of epileptic seizure-like activity and help refine models of neural connectivity that resemble electrical circuits.    The equipment is also critical to longer-term projects that seek to use "system-on-chip" technology to develop electrode arrays with integrated pre-amplification and/or analog-digital conversion hardware. Such enhancements to this equipment are aimed at significantly improving signal/noise ratios. This is an important supporting step for the bresearch community as the neural tissue is gradually affected by the implantation of electrodes and the presence of the electrical stimulus. In essence we are trying help electrophysiologists to obtain useful data quicker than at present. This represents an excellent opportunity for electrical engineering students as they are exposed to an exciting interdisciplinary research environment.