Measurement of evoked potentials

Abstract

Techniques for recording evoked potentials (EPs) have reached an advanced state and, in many places, these techniques are successfully performed. Special purpose computers, such as averagers or instruments performing Fourier transforms, are to be found even in small departments: in large centres general purpose computers are in current use. Moreover, technical literature on the subject is abundant, for example the EEG Journal Supplements ^{1, 2}, the EEG Handbook ³, Regan’s book⁴ Desmedt’s book⁵ and many other publications, where a number of basic problems have been lucidly discussed by specialists in the field. At first sight a discussion here of the basic principles involving EP recording may appear superfluous. However, the wide availability of modern computing facilities leads to evermore sophisticated procedures (as reflected in the growing literature on extraction techniques and system and filter analysis) and the need for a re-evaluation of these newer techniques with respect to some basic principles is pertinent. This chapter is an attempt to clarify and understand some of the newer techniques using a more ‘conceptual’ approach, and also an attempt to provide a critical evaluation.