[Analysis of functional architecture of the brain by optical recording methods]

To date, our understanding of the elaborate mechanism that governs the information processing of neural tissue or the brain is based mainly on data obtained from single-electrode recordings in vivo or in vitro. The refinement of electrophysiological techniques has advanced our knowledge about neural information processing, but clearly, we are still far from complete and coherent understanding of these brain functions. Although conventional approaches have provided the bulk of our knowledge about neural information processing, there is clearly a need for research tools that are better suited to investigate the detailed properties of individual neurons on the one hand and allow for studying the interactions between large numbers of neurons on the other hand. The use of optical recording methods with voltage-sensitive dyes (extrinsic optical signal recording) seems to be one of the most promising ways to attack the above problems. This approach allows to record the neural activity at many sites simultaneously and thus provides spatio-temporal information about the flow of electrical activity in a given preparation. The optical recording without using voltage-sensitive dyes, intrinsic optical signal recording, is also useful to detect the neural activity in the brain. The signal is thought to be originated from the metabolic change of the brain tissue which is associated with the change in neural activity. We compared the both activity mapping obtained with extrinsic signals and intrinsic signals. This kind of trial seems to be useful not only for understanding the origin of the metabolic signal, but also for treating the data obtained with PET or functional MRI.