Neurons in the Rostral Cingulate Motor Area Monitor Multiple Phases of Visuomotor Behavior With Modest Parametric Selectivity

1 Department of Physiology, Tohoku University School of Medicine, Sendai; and 2 The Core Research for Evolutional Science and Technology Program, Japan Science and Technology Agency, Kawaguchi, Japan Submitted 22 November 2004; accepted in final form 3 February 2005 We examined the cellular activity in the rostral cingulate motor area (CMAr) with respect to multiple behavioral factors that ranged from the retrieval and processing of associative visual signals to the planning and execution of instructed actions. We analyzed the neuronal activity in monkeys while they performed a behavioral task in which 2 visual instruction cues were given successively with an intervening delay. One cue instructed the location of the target to be reached; the other cue instructed which arm was to be used. After a second delay, the monkey received a motor-set cue to be prepared to initiate the motor task in accordance with instructions. Finally, after a GO signal, the monkey reached for the instructed target with the instructed arm. We found that the activity of neurons in the CMAr changed profoundly throughout the behavioral task, which suggested that the CMAr participated in each of the behavioral processing steps. However, the neuronal activity was only modestly selective for the spatial location of the visual signal. We also found that selectivity for the instructional information delivered with the signals (target location and arm use) was modest. Furthermore, during the motor-set and movement periods, few CMAr neurons exhibited selectivity for such motor parameters as the location of the target or the arm to be used. The abundance and robustness of the neuronal activity within the CMAr that reflected each step of the behavioral task and the modest selectivity of the same cells for sensorimotor parameters are strikingly different from the preponderance of selectivity that we have observed in other frontal areas. Based on these results, we propose that the CMAr participates in monitoring individual behavioral events to keep track of the progress of required behavioral tasks. On the other hand, CMAr activity during motor planning may reflect the emergence of a general intention for action. Address for reprint requests and other correspondence: J. Tanji, Department of Physiology, Tohoku University School of Medicine, Seiryo-cho 2-1, Aoba-ku, Sendai 980-8575, Japan (E-mail: tanjij{at}mail.tains.tohoku.ac.jp )