Simultaneous microelectrode recording of layered structure of cortex and tonotopic structure of thalamus in the auditory pathway

Simultaneous characterization of layer-specific activation in the cortex and topographically organized activation in the thalamus brings substantial benefits to advance the understanding of the sensory/motor functions. We designed a silicon-probe microelectrode array to simultaneously characterize the primary auditory cortex (A1) and thalamus (medial geniculate body; MGB), which are aligned in the dosro-lateral to ventro-medial axis perpendicular to the cortical surface of A1. The array had 3 shanks with 6-mm length. On each shank, 15 recording sites were made at the tip for MGB and 17 sites were made at the bottom for A1. A laser displacement meter was proved useful to make appropriate insertion of the array probe at a right angle with respect to the cortical surface. Our experiments in vivo demonstrated the capability of the designed array to investigate the thalamo-cortical interaction between tonotopically organized activities in the thalamus and layer-specific activities in the cortex.