Measurement of propagation velocity driven by current microstimulation in the mouse auditory cortex in vitro

Abstract

All sensory cortical areas, including the auditory cortex, are considered to be wired according to the same general laminar structure schema, commonly referred to as the canonical model of cortical circuitry. The auditory cortex in vivo, however, is functionally anisotropic; the functional organization along the tonotopic axis is qualitatively different from that orthogonal to this axis. In the current study, we examined whether the functional anisotropy of the auditory cortex observed in vivo is reflected in propagation activity driven by electric stimulation in the local microcircuitry in vitro. Using in vitro preparations of coronal and angled horizontal brain slices, we directly investigated their isotropic versus anisotropic properties using microstimulation and multi‐site recording with a multielectrode array substrate. Our results clearly demonstrated the isotropic properties of the circuits in slice preparations of the auditory cortex. Additionally, we found that driven by stimulation current in layer 4, the horizontal velocity of activity propagation in layer 2/3 was faster than the vertical velocity from layer 4 to layer 2/3 and the horizontal velocity in layer 4. On the basis of these results, we discuss the local network and its possible functions in the auditory cortex. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.