The researchers found that Broca's area--which lies on the left side of the brain about in the temple region--and its counterpart on the right side activate when people are asked to organize plans of action. They said their finding of the general executive function of Broca's area could explain its key role in language production.
Importantly, the researchers found that this executive function of these cortical regions was distinct from the organization of temporal sequences of actions.
The researchers, Etienne Koechlin and Thomas Jubault of Universit Pierre et Marie Curie and Ecole Normale Suprieure, described their experiments in the June 15, 2006, issue of Neuron.
In their experiments, the researchers asked volunteers to execute a sequence of button presses when they saw colored squares or letters on a screen. Koechlin and Jubault designed their experiment so that they could precisely distinguish hierarchical planning of tasks from the temporal organization of tasks. The subjects were asked to perform both simple sequences of button presses in response to a stimulus, "simple action chunks," and "superordinate action chunks." Simple action chucks were single motor acts that required sequential action. Superordinate action chunks included "a sequence of categorization tasks, like sorting a deck of playing cards first by color, then by suit, then by rank."
While they performed the tasks, the subjects were scanned using functional magnetic resonance imaging. This scanning technique involves using harmless magnetic fields and radio waves to measure blood flow in brain regions, which reflects
Contact: Heidi Hardman