Same Areas of the Brain Prepare for and Respond to a Stimulus, Say Experts

by Ann Samuel on  March 7, 2007 at 4:36 PM Mental Health News   - G J E 4
Same Areas of the Brain Prepare for and Respond to a Stimulus, Say Experts
Scientists have smashed preconceived notions of brain function in the field of conducting tasks that involve spatial processing, such as, preparing to move when a traffic light turns green.

Researcher Eric Schumacher, assistant professor of psychology at the Georgia Institute of Technology and colleagues, were surprised when they conducted MRI brain scans of their subjects during an experiment.

The researchers were testing the notion that areas of the brain involved in tasks of spatial processing, which are the superior parietal cortex, known for its involvement in spatial attention, and the premotor cortex, known for planning movements, are activated before the prefrontal cortex, which is known for its role in decision-making.

Admitting that he found the notion wrong, Schumacher says: "We found that all of these regions began to activate when the subjects prepared to do the task, even the prefrontal, which is the region that makes the decision on what to do.

"Activating the decision-making region even before the stimulus is presented seems to allow for a quicker response, it allows the brain to get a running start."

The experiment was carried out by loading the subjects into an MRI scanner. They were then shown a disk on a screen, and prompted to press a button, when needed.

The subjects had two different tasks to perform, one labeled easy, and one hard. During the easy task, subjects were asked to push a button using the fingers of their left hand if the disk appeared on the left of the screen and their right hand if the disk appeared on the right. The hard task was manually incompatible, so that if the disk appeared on the left, they were to push the buttons using their right hand and vice-versa. Sometimes a visual cue prompted them that they were about to perform the hard or the easy task, sometimes it did not.

When the tasks were cued, all three regions of the brain increased their activity. When there was no cue, there was less activity.

Says Schumacher, "My research suggests that preparation for an upcoming change and appropriate responses involves the same brain regions that are involved in actually carrying out the action."

The findings were published in the online journal Brain Research.

Source: Newswise

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