The present disclosure provides an apparatus including: one or more needle-like bases enabled to be inserted into the brain; a first electrode having a first impedance and enabling an input of an electric activity of a nucleus with which the first electrode comes into contact; and a second electrode having a second impedance lower than the first impedance and being able to output an electric stimulation to the nucleus, wherein the first electrode is provided at a tip portion of at least one of the bases, and the second electrode is provided on a part of the at least one of the bases at a position identical to a position of at least one of the first electrode or on a proximal side with respect to the first electrode, in a direction along a long axis of the base on which the first electrode is provided.