The difference between the left and right sides of the human brain has long fascinated scientists and non-scientists alike. The idea that the left hemisphere supports language and rational thought, while the right hemisphere supports creative processes has firmly taken root in popular culture, and has led some to call for an increase in “right-brain thinking”. Such imprecise use of the scientific literature may seem cringeworthy to scientists, myself certainly included. How exactly, I would ask indignantly after hearing such calls, are we supposed to consciously control activity in one brain half over the other?
Turns out that that part of the problem might actually be fairly simple. New research from the lab of Fabien Robineau in Switzerland suggests that an fMRI scanner and a thermometer may be all that is required.
The experiments make use of Neurofeedback, in which subjects are trained to control activity in specific parts of their brain. Typically, they are instructed to engage in a mental activity that is known to activate the area of interest, while undergoing fMRI scanning. A thermometer on a monitor feeds the degree of activation of the brain region back to the subject, and the goal is to maximize the thermometer reading. One of the truly amazing features of the brain is that it can learn to control almost anything if provided with appropriate feedback, as evidenced by the dazzling variety of skills humans can learn. And indeed, subjects can learn to increase of decrease activity in many parts of their own brains with such procedures.
This approach could be very useful, because many psychiatric and neurological conditions are associated with over-activation of brain areas. In one of the more impressive applications of neurofeedback to date, scientists demonstrated that chronic pain patients could learn to down-regulate activity in a part of the brain that mediates pain, which resulted in substantial reductions in pain perception.
In the Robineau paper, these procedures were applied to selectively activate one side of the brain over the other. Subjects were placed in an fMRI scanner and watched a thermometer that showed the degree of activation of one side of their visual cortex compared to the other side. The instructions were to engage in mental visual imagery in order to maximize the thermometer reading. Amazingly, over three such sessions, most subjects learned to control the degree of activation of the left versus right visual cortex, and they could even reproduce this activation in the absence of feedback.
The authors looked at visual perception because of its relevance to hemispatial neglect, which is a neurological condition that may be caused by imbalanced in activation of the left and right visual cortex. However, in principle similar procedures could be applied to functions that are more likely to ignite the popular imagination, such as creativity, language and rationality. The only caveat there is that research has shown that such broad functions are partly supported by both hemispheres.
Still, it’s a clear proof of principle, and what is to say science will not prove the sceptics wrong once again?