Visual evoked potentials and our studies

Abstract

Evoked potentials are electrical responses of the brain to light, sound, or electrical stimuli. Depending on the type of stimulus, they emerge as visual, auditory, or somatosensorial evoked potentials. Visual evoked potentials (VEPs) are electrophysiological signals taken from the electroencephalographic activity of the visual cortex and recorded the scalp over the cortex. VEPs depend on the functional integrity of the visual pathways at any level including optic components of the eyes, retina, optic nerve, optic chiasm, optic radiations, and the visual cortex. On the pattern VEP recordings, 3 main components are observed which are called N75, P100 and N145. There are two types of recordings, known as pattern VEP and flash VEP. The presence of dopamine in the inner plexiform layer of the retina in mammals including humans and the fact that dopamine is not known to be an important transmitter anywhere in the visual system except for the retina, suggests that VEP abnormality is of retinal origin. Factors affecting VEP latency and amplitude include inflammation, hypoxia, and atherosclerosis. We have several publications on this topic on different groups of patients. This chapter of the book was intended to be written in order to explain and comment on our studies as well as the others on the definitions, types, recordings, waves, commenting normal and abnormal responses. Physiology and the pathophysiological mechanisms underlying abnormal VEPs will also be discussed. © 2020 Nova Science Publishers, Inc..