This paper presents a new concept of functional microwave imaging using m-sequence multiple-input multipleoutput (MIMO) radar as a non-ionizing application of functional brain imaging. The underlying hypothesis is that, if we can detect local changes in blood volume inside the brain precisely enough, we can infer which parts of the brain are activated when performing various tasks. In this point of view, the main challenge in terms of MIMO radar framework is multi-target localization based on time of arrival (TOA) results. For this purpose, we present a multi-lateral localization approach in collocated MIMO-radar to detect single target inside brain medium. A system concept is introduced, and results from simulations using a simplified physical model are presented. To validate this, we focus on the waveform diversity and signaling strategies options for short range sensing. Simulated results validate the effectiveness of the proposed methods for precisely calculating the time-dependent location of target.