The Journal of Neuroscience, July 9, 2008, 28(28):7209-7218; doi:10.1523/JNEUROSCI.0487-08.2008
Previous Article | Next Article 
Behavioral/Systems/Cognitive
Role for Subthalamic Nucleus Neurons in Switching from Automatic to Controlled Eye Movement
Masaki Isoda1,2 and
Okihide Hikosaka1
1Laboratory of Sensorimotor Research, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892, and 2Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan
Correspondence should be addressed to Dr. Masaki Isoda, Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan. Email: isodam{at}brain.riken.jp
The subthalamic nucleus (STN) of the basal ganglia is an important element of motor control. This is demonstrated by involuntary movements induced by STN lesions and the successful treatment of Parkinson's disease by STN stimulation. However, it is still unclear how individual STN neurons participate in motor control. Here, we report that the STN has a function in switching from automatic to volitionally controlled eye movement. In the STN of trained macaque monkeys, we found neurons that showed a phasic change in activity specifically before volitionally controlled saccades which were switched from automatic saccades. A majority of switch-related neurons were considered to inhibit no-longer-valid automatic processes, and the inhibition started early enough to enable the animal to switch. We suggest that the STN mediates the control signal originated from the medial frontal cortex and implements the behavioral switching function using its connections with other basal ganglia nuclei and the superior colliculus.
Key words: subthalamic nucleus; basal ganglia; monkeys; saccades; habitual action; conscious control
Received Feb. 3, 2008;
revised May 7, 2008;
accepted June 4, 2008.
Correspondence should be addressed to Dr. Masaki Isoda, Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan. Email: isodam{at}brain.riken.jp