Chapter 4 - Evoked Potentials Studies of Visual Information Processing

Abstract

Sensory and perceptual processes of the human mind have been extensively studied in the past by psychophysical methods. Modern neurosciences offer several anatomical and physiological methods to complement such studies by analyzing the neurophysiological correlates of sensory information processing. For the study of perception and cognition, measures with very high temporal resolution are needed. This is reflected by the fact that brain mechanisms related to perception are fast, and that individual steps in information processing are associated with rapid changes of the spatiotemporal characteristics of spontaneous and evoked electrical brain activity. This chapter illustrates how the recording of brain electrical activity in combination with knowledge of the human visual system may be employed to study information processing. Neurons communicate by transmitting membrane potential changes to their neighbors in their synaptic endings, and are able to connect different structures by sending information in the form of frequency-modulated action potentials of constant amplitude over long distances in the brain. The noninvasive recording of evoked potentials constitutes a powerful supplement to psychophysical testing, and may reveal steps of information processing with a high resolution in the time domain.