Direct mapping of bioelectric activity

Much can be learned about physiological function in heart, brain, and other tissues from measuring the electrical activity that mediates mechanical or neural phenomena. The study of electrophysiology has progressed from acquisition of a single or a few channels to hundreds of signals acquired simultaneously. Data acquisition, signal processing, and visualization in electrophysiology have benefitted from the parallel advances in electronics and computing hardware and software. The two primary technologies for mapping electrical activity at many sites are electrical, using electrodes directly placed on tissue, and optical, using voltage sensitive dyes to estimate membrane parameters. Each is valuable and provides information that is complementary to the other. This article is a description of the current state of electrical and optical mapping.