Abstract
We studied activity-dependent cortical plasticity in C57BL/6 mice using transcranial flavoprotein autofluorescence imaging. In the auditory cortex, we tested the effect of acoustic environment on the cortical activities. Neural responses in the auditory cortex elicited by sound stimuli (5-20 kHz) exhibited tonotopic maps. In mice exposed to environmental stimuli (10 kHz, 70 dB), the cortical responses to 10 kHz stimuli were augmented in a frequency-specific manner. In the visual cortex, effects of monocular deprivation for 4 days in the critical period were evaluated a few weeks after the deprivation. Monocular deprivation selectively diminished the autofluorescence responses to light stimuli applied to the deprived eyes in the binocular zone but not in the monocular zone of the visual cortex. In the somatosensory cortex, effects of tail amputation were investigated. Neonatal mice were anesthetized with ether, and the tail was cut at the base. Cortical activities were evaluated 2-13 weeks after the tail amputation. In control mice, an activity-dependent autofluorescence increase was observed in the hindpaw, tail base and tail tip regions, which were adjacent to each other in the posterio-medial direction. In the tail-amputated group, the tail base region shifted toward the region corresponding to the tail tip in control mice. Furthermore, the tail base and hindpaw regions were expanded toward the border between them. The present results indicate the usefulness of transcranial autofluorescence imaging for investigating activity-dependent plasticity of mouse sensory cortices. [Jpn J Physiol 55 Suppl:S58 (2005)]
