Introduction

Nearly 50 years ago, it became possible to study in some detail the electrical activity of the brain by recording evoked potentials.²² This chapter begins by describing the growth of this discipline and then summarizes how the evoked potentials originate from activity transmitted from the retina to the visual cortex and what aspects of cortical function they demonstrate. This gives the framework against which clinical tests may be developed and enables an appreciation of their value in clinical diagnosis. The different modalities that are used to evoke cortical potentials as well as the important parameters that are involved are discussed. The different types of evoked potentials are described, and the concept of VEP latency is discussed. More technical issues of recording and analysis are also covered.