Imaging of neuronal activity in the gut.

Over the past few years, several groups have used voltage-sensitive dyes or calcium-indicator dyes to optically monitor the activity of several enteric neurons simultaneously. Some of the initial practical problems have been solved and these studies have successfully shown the spread of electrical activation within the enteric neuronal circuitry in cultures and in ex vivo specimens. The basic mechanisms underlying voltage-sensitive dye or calcium-indicator signals and their relation to changes in membrane potential need further investigation. Application of these techniques will provide more insight into neuronal interaction and spread of activation. The ability to simultaneously record activity in other cells in the same focal plane offers the potential to investigate how the integrated neuronal circuits are linked to effector cells in their close neighbourhood. Progress in optical imaging of enteric neuronal activity should ultimately lead to a better knowledge of gastrointestinal physiology and pathophysiology.