Higher motor areas share their roles in controlling action sequences
In a recent issue of Journal of Neuroscience, Nakajima et al. showed complementary roles of two motor-related areas in the primate frontal lobe in controlling motor sequences.
Research background and overview
In our everyday life, we often have to follow a certain action sequence to attain our behavioral goal or reward. A good example is the sequence to open a locked door: one has to first turn a key to unlock it before turning the doorknob. Although we know the final action in the sequence that ultimately leads to the goal, it often needs to be withheld while performing the preceding action properly. There are multiple motor areas in the primate frontal lobe (Fig. 1). Among them, the dorsal premotor area (PMd, lateral sector) and pre-supplementary motor area (pre-SMA, medial sector) are involved in the control of motor sequences. However, it was not clear how these two areas contribute to coordination of sequential movements differently. This is because few studies had directly compared neuronal activity in medial- and lateral sectors of the higher motor areas while performing motor sequences. To address this issue, Nakajima et al. recorded single-cell activity in both areas while monkeys memorized and performed multiple motor sequences each of which comprised a series of two movements to obtain a reward. Their findings suggest that the PMd preferentially represents the final action that ultimately leads to a reward in a prospective manner, whereas the pre-SMA coordinates switching among multiple actions within the context of the sequence (Figs. 1 and 2).
Significance of findings
Their findings are of significance to understand the distinct roles for motor-related areas in the planning and executing motor sequences and the pathophysiology of apraxia and/or Parkinson’s diseases that disables skilled motor actions.
Original article information
Toshi Nakajima1, Ryosuke Hosaka2 and Hajime Mushiake3
1Department of Integrative Neuroscience, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama, 930-0194, Japan
2Department of Electronic Information Systems, College of Systems Engineering and Science, Shibaura Institute of Technology, Saitama, 337-8570, Japan
3Department of Physiology, Tohoku University School of Medicine, Sendai, 980-8575, Japan
Title of the original article
Complementary roles of primate dorsal premotor and pre-supplementary motor areas to the control of motor sequences (in press)
Journal of Neuroscience