Deep-Brain Transcranial Stimulation: A Novel Approach for High 3-D Resolution

Abstract

This research was performed to investigate the ability of transcranial magnetic stimulation (TMS) to evoke the deeper areas of the brain with a minimal impact on non-target areas. To reach this goal, a novel core design in a semi-hexagonal shape with the arrow tips was utilized to collect a magnetic field in the selected target region. In addition, a new circuit topology was presented to generate stimulative pulses with optimal amplitude, frequency, and duration. For the first time in this research voxel resolution was proposed and exploited to evaluate the TMS system accuracy. To study the induced potential in different parts of the brain and its related resolution, a custom-made recording electrode and a micromanipulator were employed. They provided the linear movement in all Rostral/Caudal, Dorsal/Ventral, and Medial/Lateral orientations. The ARM cortex-M microcontroller managed the stimulation and recording sessions. After performing the finite element analysis, the researcher developed a prototype of the proposed system and tested it in vivo on the intact WAG/Raj rat. The results showed that spatial resolution could be significantly enhanced by employing the proposed TMS concept. The outcome of animal trials have raised some hopes to apply the knowledge of this article in the clinical contexts.

Keywords

• Transcranial magnetic stimulation
• target selectivity
• stimulation coil/core shape
• measuring voxel resolution