A team of BRAIN researchers reveal a new brain region, the Rolandic Motor Association area, that contributes to body movement and might have an essential role in coordinated complex behaviors.
In a recently published study in Nature Neuroscience, BRAIN funded researchers Kai Miller, M.D., Ph.D. and Peter Brunner, Ph.D. reveal a brain region buried in the mid-lateral aspect of the central sulcus (a part of the brain that separates primary motor cortex from primary somatosensory cortex) that becomes active during different movements of different body parts from both sides of the body. The team has termed this region the Rolandic Motor Association (RMA), and because it does not appear to be related to any single movement function, they believe it to be an association area that helps to coordinate complex movements. This breakthrough discovery may help improve our understanding of how networks of neurons in the primary cortex and motor association areas work together to produce behavior.
Initially, the researchers set out to characterize the electrophysiological characteristics of the primary motor cortex in a three-dimensional volume. The study was comprised of 13 people aged 11 to 20 with a history of drug-resistant partial epilepsy and with stereoelectroencephalographic (sEEG) electrodes inserted directly in their brains for clinical purposes. The patients were asked to perform basic tasks involving tongue, hand, and foot movement with rest in between, while electromyography (EMG) was recorded from each of those areas.
To the researchers’ surprise, recordings from all 13 study participants showed that the RMA interrupts the somatotopic mapping of the "homunculus," the organized representation of the brain regions responsible for different body movements, and appears to respond broadly and bilaterally, indicating potential involvement in coordinating large-scale neural motor activities. This finding adds to a growing body of evidence suggesting that motor association areas, such as the RMA, might have integrative roles to coordinate behaviors along with the primary motor cortex.
The researchers intend to pursue a follow-up study to further explore the functional role of the RMA in motor circuitry and behavior, including its interactions with the primary cortex and other motor association areas.