Neural linkage between motivation and motor functional recovery through rehabilitative training

The joint research team consisting of Associate Professor Yukio Nishimura, and Professor Tadashi ISA from the National Institute for Physiological Sciences, Dr. Hirotaka Onoe, Team Leader in the Functional Probe Research Laboratory of RIKEN, the Center for Molecular Imaging Science, and also Dr. Hideo Tsukada, Manager of PET Center, Hamamatsu Photonics K.K., Central Research Laboratory, revealed that the more motor function recovery progresses, the stronger the functional connectivity between the brain which regulates motivation, and in the brain regions involved in the motor learning and functional recovery. This occurs through rehabilitative training of macaque monkeys after the spinal cord injuries. The result of this study suggests that the functional recovery of motor system for a patient with damage to the central nervous system can be advanced effectively, by activating the brain region which controls "motivation."

The result of this study was reported in the PLoS ONE on September 28, 2011.

The research team focused on "the limbic system," a neural circuit of the brain which is involved in regulation of the subject. "The limbic system" includes the brain region called"the nucleus accumbens." A longitudinal study of activities in this brain region using positron emission tomography (PET) revealed that the more motor functional recovery progresses, the stronger became the functional connectivity between the activities in "the limbic system" and "the motor cortex." It was also revealed that not only the nucleus accumbens but also other "motivation centers" such as orbitofrontal cortex and anterior cingulate cortex also increased connectivity with the motor circuits.

Associate Professor Nishimura says, "Actually, depressive symptoms after brain and spinal cord injuries are a hindrance to functional recovery of motor systems in rehabilitation. From the result of this study, we say not only training of the motor functions, but also psychological support and psychiatric regulation of emotion should be important in rehabilitative training."