It has been known for over 100 years that if a person suffers a stroke in the left frontal cortex, he or she often suffers difficulties in speaking and with understanding language. However, because of these language impairments, it has been difficult for researchers to test the abilities of such patients on other tasks, and thereby gain further understanding of the role of the frontal cortex.
Now, Gorana Pobric of the International School for Advanced Studies in Trieste, Italy, and Dr. Antonia Hamilton of Dartmouth College have used Transcranial Magnetic Stimulation, which disrupts brain function in healthy volunteers for less than a second, to test the role of frontal cortex in tasks other than language. The findings are reported in the March 7th issue of Current Biology.
In their study, the researchers showed participants video clips of a person lifting up a box, and asked the participants to determine the weight of the box by paying close attention to the actions of the actor. Normally, participants can succeed in this task without much trouble, but performance was significantly impaired if the left frontal cortex was stimulated while the videos were shown. This result indicates that the left frontal cortex is necessary for understanding other people's actions, and it implies that people who suffer strokes to this region may also have difficulty understanding actions or gestures. Knowing more about the function of this brain area will help researchers develop better ways to communicate with stroke patients and understand more about how language and actions interact in the normal brain.