2. Literature Review

Many facets of bioelectric activity have been investigated using both animal and human models. The scope of bioelectric research is wide, ranging from alterations in skin potentials in response to psychological stress and sleep, through to changes in cell membrane potentials in response to external electrical stimulation. In an attempt to establish some order to the breadth of research, an organisational model was constructed, grouping the research efforts by general headings. This model is inevitably both incomplete and open to interpretation, but aims to provide a background to the scope of the subject from which some elements are reviewed herein. Much of the published research is of peripheral relevance to the current project, and although important in the overall context of bioelectric research, is not considered in detail in this review. There are many cross links that exist within the framework which are not illustrated for the sake of clarity. The organisational structure of the subject is shown in Figure 2.1.