title: Arm movements induced by electrical microstimulation in the superior colliculus of the macaque monkey.
abstract: Neuronal activity in the deep layers of the macaque (Macaca mulatta) superior colliculus (SC) and the underlying reticular formation is correlated with the initiation and execution of arm movements (Werner, 1993). Although the correlation of this activity with EMGs of proximal arm muscles is as strong as in motor cortex (Werner et al., 1997a; Stuphorn et al., 1999), little is known about the influence of electrical microstimulation in the SC on the initiation and trajectories of arm movements. Our experiments on three macaque monkeys clearly show that arm movements can be elicited by electrical microstimulation in the deep layers of the lateral SC and underlying reticular formation. The most extensively trained monkey, M1, extended his arm toward the screen in front of him more or less stereotypically upon electrical SC stimulation. In two other monkeys, M2 and M3, a larger repertoire of arm movements were elicited, categorized into three movement types, and compared before (M3) and after (M2 and M3) training: twitch (56% vs. 62%), lift (6% vs. 5%), and extend (37% vs. 32%), respectively. Therefore, arm movements induced by electrical stimulation in the monkey SC represent a further component of the functional repertoire of the SC using its impact on motoneurons in the spinal cord, probably via premotor neurons in the brainstem, as well as on structures involved in executing more complex movements such as target-directed reaching. Therefore, the macaque SC could be involved directly in the initiation, execution, and amendment of arm and hand movements.
authors.affiliation: Faculty of Biology and Biotechnology and Department of Neuroscience, Ruhr University, 44780 Bochum, Germany, and Sobell Department of Motor Neuroscience and Movement Disorders, University College London Institute of Neurology, London, United Kingdom WC1N 3BG.
authors.forename: Roland
authors.initials: R
authors.lastname: Philipp
authors.forename: Klaus-Peter
authors.initials: KP
authors.lastname: Hoffmann
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001132:Arm / Q000502:physiology*; D001931:Brain Mapping; D004558:Electric Stimulation; D007839:Functional Laterality / Q000502:physiology; D008253:Macaca mulatta; D008297:Male; D009068:Movement / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D011597:Psychomotor Performance; D011930:Reaction Time / Q000502:physiology; D018709:Statistics, Nonparametric; D013477:Superior Colliculi / Q000166:cytology* / Q000502:physiology*; D014738:Vibrissae / Q000294:innervation; D014794:Visual Fields / Q000502:physiology
keywords: electrical microstimulation; forelimb movement; midbrain; nonhuman primate; reticular formation; superior colliculus