Using TMS to pinpoint neural center of risk-taking behavior

Neuroscience back in the day would rely on injured brains (soldiers returning from battle, Phineas Gage ...) in order to determine functions of specific parts of the brain.

(NOTE: ...or even that there are functions of specific parts of the brain. After WWI, for example, many soldiers surviving gunshot wounds to the back of the head suffered from cortical blindness, but displayed the curious phenomenon of motion sparing. We know now that the wound affected lower visual areas while leaving area MT unharmed, but at the time no one believed motion sparing was real - they were convinced that visual information was processed as a whole.)

Transcranial Magnetic Stimulation (TMS) is a way to temporarily deactivate localized regions of the brain - with a specific area "turned off" it is possible to look at changes in behavior and draw conclusions about what that part of the brain does, similar to the lesion studies conducted in the early days of neuroscience.

A TMS study in today's issue of the Journal of Neuroscience implicates the dorsal right prefrontal cortex in risk-taking and decision-making behavior. Subjects completed a "gambling" type task (see figure, below) and were more likely to risk losing a large amount of "points" when TMS was being applied to the dorsolateral right prefrontal cortex......

J. Neurosci. -- Knoch et al. 26 (24): 6469 Figure 1

I personally am wary of accepting any of the proposed functions of the frontal cortex just yet - the dorsolateral prefrontal cortex alone supposedly has a role in: emotional processing, working memory, shifting visual attention, and implicit learning, among others I'm sure; even in this study, they noticed that the TMS also had an effect on subjects' mood.

While this higher-level research is interesting, I think it's important for us to have a concrete understanding of the lower-level processes that underlie these behaviors before we jump right in to the frontal cortex. Just as studying vision would be impossible without an understanding of retinotopic mapping, studying higher-level behaviors is of little value until we understand what basic processes contribute to them.

That said, this research does fit the criteria for good science in at least one respect - it opens the doors for new questions. What is the effect of alcohol on the dlrpFC? Are chemical or anatomical differences in the dlrpFC correlated with risk-taking behavior? What is the developmental timeline of the dlrpFC?

Research like this also has a tendency to interest the public in neuroscience, which can only be good for us neuroscientists.

technorati tags:neuroscience, Transcranial Magnetic Stimulation, risk-taking