The comparative studies on brain structures based on different echolocation sound of bats

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The aim of the project is to confirm that the functional structure of mastached bats also appears in the other species bats living in northern America, Europe or Japan. Such a fine cortical organization was found mainly in mastached bat from Central America by Nobuo Suga. The project invited Henning Scheich from Germany to get informations about the method of 2-DG and his findings in rodents as well as supported the communication with Suga continuously.The project also sent two of the members to Suga's laboratory and performed neurophysiological experiments in mastached bats. The study elucidated that there were a few cases in auditory cortex in which the neurons located in different cortical areas fired synchronously. The synchronization is interesting because the brain seems to integrate the sensory information in cortex. The other member studied about FM bats and found that there are neurons which represent differential firing to stimuli whose frequency is different. A member studied the responsibility of pontine neurons to sounds coming from various direction in north American FM bats and found they are more sensitive to the sounds from center rather than from peripheral direction.Two members went to Germany and studied anatomical structure of bats related to rodents using HRP methods. The study clarified the neuronal connections between medial geniculate body and auditory cortex.The vocalization sounds of Japanese bats and auditory threshold curves of CF-FM bats were analyzed also. The sound structures were similar to other species of bats living in northern and central America or Europe, which indicated that the functional structures of bats seem to be common among all species of bats performing echolocation using ultrasounds.