The brain’s motivational processes always provide an interesting area for research, as they underlie all of our “voluntary” behavior. Much progress has been made in understanding motivational areas of the brain since the advent of sophisticated neuroimaging techniques. Recently, a group of researchers using fMRI attempted to identify specific activity in the brain that takes place when a person shifts their attention to a relevant object in their environment (the first step in developing motivation to obtain the object).
The group focused on hunger, testing subjects at two separate occasions: once after eating as many Krispy Kreme donuts as they could (eight was the record), and another after fasting for eight hours. In each experimental condition, the subjects were then shown pictures, some of tools and others of donuts, while being scanned with fMRI.
As you might expect, the subjects who had just gorged themselves on donuts didn’t show increased activity in response to the donut pictures. But in those who fasted, images of donuts caused rapid activity throughout the limbic lobe—an area of the brain thought to be involved in identifying salient objects in one’s environment. Immediately after the donut was recognized, attentional mechanisms in the brain, involving the posterior parietal cortex, were also stimulated, demonstrating that the subject’s attention had been turned to the relevant object. These mechanisms seemed to work in conjunction with those that were used to gauge the importance of the object. Thus, the authors of the study suggest the posterior parietal and limbic lobe play an interactive role in identifying salient stimuli and immediately focusing one's attention on them.
This experiment provides further evidence for the concept that our brains are inherently organized to recognize aspects of our environment that are beneficial to us. Many believe the significance of certain types of stimuli is evolutionarily ingrained, meaning that our brains evolved to place importance on those that promote survival, such as food, water, or sex (which leads to dissemination of genetic information). This study goes a bit further to elucidate the mechanisms involved in the distribution of attention among salient and non-salient stimuli. If a hungry brain sees food, it will activate those attentional mechanisms to focus itself on that food, providing motivation to obtain it.
I suppose the greater task in our corpulent society right now, however, is to learn how to get people to avoid those Krispy Kreme donuts instead of to understand exactly how our brain focuses attention on them.