High-resolution EEG: translation of neuroscience into clinical context
Research Project
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01.01.2009
- 31.12.2010
Recent developments in neurophysiological methods allow more precise electric source imaging and quantitation of brain connectivity. The former permits localization of brain activity with a temporal resolution of milliseconds, the latter characterization of the network configuration of the brain. Using high-resolution recordings, evoked potentials (EP) cannot only be analyzed in regard to their latency and amplitude, but also in regard to their spatial extent, which may conveys important clinical information. Furthermore, application of source localization algorithms allows automatic analysis of EP, making measurements operator independent and probably more sensitive to change. Measures of brain connectivity are based on analysis of the electro-encephalogram (EEG) at rest. High-resolution recordings allow estimating quasi reference-independent potentials and applying methods to account for volume conduction. Connectivity measures are derived from the statistical interdependency between two electrodes, which is assumed to represent connection of the underlying brain activity. As neural synchrony probably is an electrophysiological correlate of cognitive function, brain states with cognitive impairment may be characterized by altered connectivity measures. Furthermore, global measures of the configuration of the networks of the brain can be derived from connectivity analysis, which have been shown to be abnormal in case of cognitive impairment. High-resolution EEG and high-resolution EP recordings are the core methods of the research projects described below. The main project is a SNSF-sponsored project in the Special Program University Medicine (SPUM, SNSF 33CM30-124115), which is collaborative work between the Universities of Basel, Berne and Geneva. It is a longitudinal study over three years entitled: Improved prediction and monitoring of CNS disorders with advanced neurophysiological and genetic assessment. Based on previous work, high resolution EP are evaluated in Multiple Sclerosis (MS), and high resolution EEG measures in both, MS and Alzheimer s disease (AD) in regard to their value as prognostic and surrogate markers. In view of the only weak correlation of existing markers, more sensitive tools are needed to better assess new treatment options in these two disabling disorders. As neurophysiological measures directly assess function in a quantitative and reliable way, they are good candidates to meet the requirements of valid, sensitive surrogate markers. A second project on Parkinson s disease in patients undergoing deep brain stimulation evaluates the prognostic value of high-resolution EEG in regard to the cognitive outcome after surgery, a still only marginally studied aspect but with considerable impact on patients. A planned project is to correlate of the amplitude and spatial extent of the high resolution visual EP in MS patients to the measurement of the thickness of the retinal nerve fiber layer, a direct marker of axonal loss. A further project will evaluate measures from high resolution EEG and event-related desynchronisation as diagnostic markers in patients with HIV and cognitive symptoms. 19.05.2009 11:50:20 Page - 7 - As high-resolution EEG is a non-invasive tool, posing only minor inconveniences to patients it is well suitable to be employed in a clinical context. Furthermore, acquisition and maintenance of the equipment is cheap in comparison to other modalities. These facts make high resolution EEG an effective and efficient tool to advance clinical research and consequently, patient care.
