Brain Stim and Therapeutic Modulation
I currently work in the Brain Stimulation and Therapeutic Modulation Lab at the New York State Psychiatric Institute, affiliated with Columbia University. I began working here in January of 2008 as a graduate student since at the time I was still working toward my master’s degree in biomedical engineering. Under the supervision of Dr Angel Peterchev I began working on a project entitled “Synchronization of Transcranial Magnetic Stimulation (TMS) to Endogenous Brain Rhytms.” Using LABVIEW and MATLAB, I was able to synchronize a TMS device pulse focused on the motor cortex (motor threshold sweet spot) with various characteristics of a selected EEG rhythm, or in this case mu rhythm. The subject wears a EEG cap and according to my LABVIEW algorithm, the TMS device could deliver a pulse at peaks, troughs and zero crossings of the mu rhythm. The calculations are done in real-time however a delay of about 6 ms is introduced through the use of a butterworth filter to extract the mu rhythm. The user can also set thresholds for mu rhythm power, such that the power must be above or below a certain level before it looks for the desired triggering phase. Thus, the instrumention is capable of delivering TMS pulses synchronous with a specified characteristic (phase and/or power) of a selected brain rhythm, as sensed by EEG. We hypothesize that the phase and power of endogenous brain rhythms affect the response to TMS by modulating brain excitability. Demonstration of such interaction could provide insite to the functional role of cerebral oscillations, and could be further harnessed in the service of clinical treatment. For example, by delivering TMS pulses during the phase and power of endogenous oscillations corresponding to maximum excitability, we can enhance the effect of stimulation and/or reduce the stimulation intensity required in therapeutic applications. Enhancement the effect of TMS could leverage potential clinical applications where TMS has shown moderated efficacy. Further, reducing stimulation intensity while maintaining therapeutic effectiveness can decrease risks and improve the tolerability of TMS.
The second major project that I am concurrently working on is entitled “Neural Mechanisms of Working Memory” under the supervision of Drs. Bruce Luber and Chi-Ming Chen. Although improvements in performance due to TMS have been demonstrated with some cognitive tasks, performance improvement has not previously been demonstrated with working memory tasks. In the present study, a delayed match-to-sample task (Sternberg task) was used in which repetitive TMS (rTMS) at 1, or 5Hz was applied to midline parietal cortex during the retention (delay) phase of the task. Only 5 Hz stimulation to the parietal site resulted in a significant decrease in reaction time (RT) without a corresponding decrease in accuracy. This finding was replicated in a second experiment, in which 5 Hz rTMS at the parietal site was applied during the retention phase or during presentation of the recognition probe. Significant speeding of RT occurred in the retention phase but not the probe phase. This finding suggests that TMS may improve working memory performance, in a manner that is specific to the timing of stimulation relative to performance of the task, and to stimulation frequency. Related article.
In terms of clinical experiments and studies, I also TMS tests on patients with Tourette’s, Major Depression, and Schizophrenia. We do paired pulse, silent period, long and short interval intracortical inhibition, CMCT, and I-wave stimulation.
Here you can find an even more detailed list of my accomplishments in the lab.
Kang - Different Modulation of Cortical Silent Period by Two Phases of Short Interval Inhibition
Toga - Brain Mapping
Sparked Interests from TMS
