Lysianne Beynel, Winner of the 2021 NIMH Three-Minute Talks Competition
Lysianne Beynel: Hello, my name is Lysianne Beynel. I'm a research fellow at NIH. And today, together with you, I would like to answer this question: how can we overcome the depth limitation of transcranial magnetic stimulation, or TMS, to modulate amygdala activity?
As a real spoiler, the answer is let's use functional connectivity. But first, let me introduce you to what transcranial magnetic stimulation is.
TMS is a brain stimulation approach in which we're going to place a TMS coil, on this picture, on people's head. And so if I were to place the coil on your motor cortex, I would be able to make only one of your finger to twitch. Of course, TMS is not only used for motor cortex stimulation, it's way more important than that. People use TMS as a treatment for psychiatric disorder, such as depression or PTSD. And it seems to be working well, but the efficacy remains moderate.
On the lower left, you can see that the TMS effect remains superficial. They are very close to the cortex, but they do not go deep in the brain where the limbic structures are, notably the amygdala, which is very important for psychiatric disorders.
So what we can try to do is to use functional connectivity to modulate this deeper structure through their connection with superficial structure. And this is what we tried in our study.
Participant came in for two visits. During the first visit, we have a screening to make sure they didn't have any contraindication to TMS. And then we brought them into the scanner in which we take some pictures of their brain, while they were watching scary on neutral pictures to induce amygdala activation. Once participant left the room, we did perform some fMRI analysis to find those spots in the prefrontal cortex showing a strong connectivity with the amygdala.
When participant came back on the second visit, we stimulate this spot with either active or sham TMS. And after the stimulation, we run back into the scanner and take the exact same picture to evaluate the TMS effect.
What we found is an increased activation in the prefrontal cortex, which was expected, this is the area we stimulated with TMS. But we also found an increase in activation in the amygdala, as we were trying to do.
So this is a promising and very exciting result. However, in psychiatric disorder, what we want to do is not to increase, but to decrease amygdala activation, indeed a lot of psychiatric disorders are associated with increased amygdala activation. So if we can down-regulate this activation, we could help the treatment for those patients. And to do that, we could play with the TMS frequency, or we could play with the stimulation spot we can stimulate, and there is a lot of things to do. So let's keep up with the good work.
Thank you for your attention.