The distinction is significant, said the researchers, because it yields new basic insight into a central function of behavioral planning in this higher brain region, called the lateral prefrontal cortex (PFC).
The researchers, led by Hajime Mushiake of Tohoku University School of Medicine, reported their findings in the May 18, 2006, issue of Neuron. They concentrated on a brain region called the lateral prefrontal cortex (PFC), which many studies have shown to be involved in such higher brain functions as planning. However, noted the researchers, few studies have analyzed the specific nature of the behaviors that are planned.
"To achieve a behavioral goal in daily life, we often need to plan multiple steps of motor behavior that involve selection of a series of actions," wrote the researchers. "The question arises: how are individual neurons within the PFC involved in the planning of multistep behaviors? More specifically, does the activity of PFC neurons during the process of planning reflect the multiple movements required during future actions or the individual future events that occur as a result of the actions?"
To study the detailed activity of neurons in the lateral PFC during planning, the researchers fitted monkeys with recording electrodes that could measure activity in the region's neurons.
They then taught the monkeys to perform a complex task in which the animals were required to manipulate joysticks to move a cursor on a computer screen from a starting point to a goal. Importantly, the researchers required the monkeys to maneuver the cursor within a maze to reach the goal and to perform those maneuvers in a discrete stepwise fashion with pauses