Real-time optical imaging of naturally evoked electrical activity in intact frog brain

The use of voltage-sensitive dyes and the recent development of the use of an array of photodiodes has provided a unique technique for monitoring the dynamic patterns of electrical activity in real time from a variety of invertebrate or vertebrate neuronal preparations. In the present study, this technique has been used to investigate the intact optic tectum of the frog. The authors demonstrate that optical measurements can be used for realtime imaging of spatio-temporal patterns of neuronal responses and for identification of functional units evoked by natural visual stimuli. They report also the structure of the new voltage-sensitive probe that facilitates the in vivo applications of this technique.