Stimulating Deep Brain Regions With a Magnetic Stimulator

Overview

The purpose of this study is to determine whether a special coil designed for magnetic stimulation of areas deep in the brain can affect mood and emotion in healthy volunteers. Researchers hope to better understand how the brain controls mood and motivation and what goes wrong with this process in disease. For transcranial magnetic stimulation (TMS), a wire coil is held over the scalp. A brief electrical current passes through the coil and creates a magnetic pulse that stimulates the brain. Eighteen participants, 9 men and 9 women, will be enrolled in this study. They will be assigned to one or both of the following two experiments. Experiment 1 In this experiment, researchers will test the effectiveness of a new type of wire coil. They will deliver magnetic impulses of varying strength. Approximately 150 stimulations will be given over of about 20 minutes. To determine whether the coil causes any problem with hearing, participants will undergo a hearing test immediately before and after the experiment. Experiment 2 This experiment, which has two parts, is designed to determine whether TMS can affect mood. In the first part, participants will be asked to report any changes in mood before, during and after the magnetic stimulation. In the second part, they will be asked to choose between sets of 2 identical pictures-choosing one will result in full magnetic stimulation, choosing the other will result in stimulation at 10 percent of full intensity. Participants will be compensated up to $100 for their involvement in this study.

Current magnetic stimulation techniques permit only superficial stimulation of brain, but for some purposes deeper stimulation would be helpful. The purpose of this study is to determine whether a special coil designed for magnetic stimulation of deep brain regions can affect mood and emotion in healthy human volunteers. The special coil was designed to stimulate neuronal pathways related to the control of motivation and reward, specifically, fibers connecting the cingulated or prefrontal cortex with the nucleus accumbens. Computerized theoretical calculations were made in order to optimize the coil design for maximizing the percentage of stimulation in depth relative to the cortical regions. The present study will look first at the influence of the coil on the response from motor cortex. Should there be good evidence the coil can truly be more effective in stimulating deep structures, then we will explore whether it can indeed affect mood and emotion when single pulses are applied.