抄録
Flavoprotein autofluorescence is an endogenous signal that might be applicable for functional brain imaging, but has not been applied for this purpose as widely as intrinsic signal. This technique is especially useful for imaging mouse cortical activities, because the skull of mice is transparent enough to visualize brain autofluorescence via the intact skull. In the present study, therefore, we tried to record neural activities in the auditory cortex in anesthetized mice with this technique. C57BL/6 mice (5-7 week old, both sexes) were anesthetized with urethane (1.6 g/kg, i.p.). The skin covering the skull was incised, and the temporal muscle over the right auditory cortex was removed. The exposed surface of the skull was covered with liquid paraffin to prevent drying and to keep the skull transparent. Autofluorescence responses in the auditory cortex were elicited by sound stimuli (5-20 kHz for 500 ms), and recorded with a cooled CCD camera attached to an epifluorescence binocular microscope. The responsive areas in the primary auditory cortex exhibited a tonotopy map, which was compatible with previously reported electrophysiological studies. The brain imaging via the intact skull is expected to be useful for investigating neural plasticity, since it can be achieved without surgical damages on the brain. Therefore, we are now investigating modification of the tonotopy map after sound exposure with various parameters. [Jpn J Physiol 54 Suppl:S167 (2004)]
