Researchers Pinpoint Brain Region That Manages Multistep Tasks
Brain injury, diseases can easily disrupt this area that helps control behavior, study finds
WEDNESDAY, Sept. 23, 2015 (HealthDay News) -- Scientists say they have pinpointed a region of the brain that helps you complete a series of activities in the right order, such as getting dressed and carrying out typical daily routines.
The study authors say that the area, the rostrolateral prefrontal cortex (RLPFC), is like a foreman that helps you remember what to do step by step.
"We're interested in the errors people make in everyday sequences of behavior," study co-author David Badre, associate professor of cognitive, linguistic and psychological sciences at Brown University, said in a university news release. "You have to internally monitor where you are and what you are doing."
Led by postdoctoral fellow Theresa Desrochers, researchers gave volunteers four-step tasks to complete. Participants had to identify the shape or color of four images in various orders -- such as shape, shape, color, color; or shape, color, color, shape -- remembering the sequences as they progressed.
As volunteers completed this task, the researchers used brain imaging, known as functional MRI, to analyze patterns of brain activity.
The study found that activity in the RLPFC ramped up as volunteers completed a sequence, and dropped before a new sequence began. This could reflect participants' increasing uncertainty about their position in a sequence as they progressed, the study authors suggested.
The researchers investigated this idea further using transcranial magnetic stimulation, which can be used to briefly trigger activity in a specific area of the brain.
"This volley of neural activity is akin to static over a phone line, noise that other neurons listening in cannot interpret," Badre said.
The investigators used this technology to learn about participants' accuracy at various stages when the brain's control regions were disrupted, they explained in the news release.
Disrupting the RLPFC, in particular, led to more mistakes as the sequences progressed. The researchers suggested that the region has more uncertainty to manage as the tasks advance, correlating with increased brain activity on the fMRI. The later in the sequence the stimulation was used, the more errors participants made, according to the study published Sept. 23 in Neuron.
"When we disrupt it, we are disrupting that process of resolving the uncertainty," Desrochers said. "We, therefore, get this increasing pattern of errors because there was more uncertainty to be dealt with."
The findings shed new light on what facilitates healthy behavior, the study authors said.
"The health consequences are big," Badre said in the news release. "Cognitive [mental] control of behavior is very fragile, and it is easily disrupted by neurological disease and disorder, like stroke or traumatic brain injury. Among the major complaints in everyday life among these patients is an inability to complete multistep tasks."
The U.S. National Institute of Neurological Disorders and Stroke provides more information on the human brain and how it works.