抄録
We investigated the properties of functional connections in the primary (S1) and secondary (S2) somatosensory cortex in rat cortical slices. S1 and S2 were identified according to the myeloarchitecture, which could be visualized in the translucent images of fresh slices illuminated by near vertical light. Neural activities were elicited by repetitive electrical stimulation, and visualized by green (500-550 nm) autofluorescence of flavoproteins in blue (450-490 nm) light. The stimulation applied in S1 produced neural responses spreading into S2 beyond the areal boundary between S1 and S2. However, the neural activities were not invaded into S1, when S2 was stimulated. This anisotropic information flow of neural activities probably reflects the physiological information flow from S1 to S2 in vivo. We also investigated activity-dependent changes in the neural activities in the barrel cortex. One or two weeks after trimming whiskers, slices were prepared from the contralateral barrel cortex. In these sensory-deprived slices, supragranular neural activities after stimulation of infragranular layers were clearly suppressed. These results suggest that flavoprotein autofluorescence imaging in the slice preparations are useful for investigating not only the properties of functional connections between S1 and S2 but also activity-dependent modification in somatosensory neural circuits. [Jpn J Physiol 54 Suppl:S145 (2004)]
