Abstract
Microelectrode arrays are commonly used to measure
neural activities in the brain, and arrays with some 100 electrodes are commercially available to date. However, insertion of dense grid array deforms the brain, resulting in deterioration of the measurements. In order to overcome this problem, we propose a piezo-driven vibrating insertion device to reduce the inseritoninduced deformation of the brain. We attempted under various conditions of the insertion of the array into an agarose substrate, whose hardness was adjusted to that of the cerebral cortex of rats. Our experiments demonstrated that inverse-sawtooth vibration reduced the insertion-induced deformation of the substrate in proportion to the logarithm of an upstroke velocity when the velocity was higher than 10 mm/s, and vibrating insertion of the maximum velocity at 36.7 mm/s reduced the deformation by up to 40% as compared to vibration-free insertion. In addition, we tested the vibrating insertion device in an electrophysiological experiment in the rat auditory cortex in vivo, and successfully measured toneevoked neuronal activities, suggesting that the vibration during the insertion did not cause fatal damage to the brain.
