title: Different modulation of common motor information in rat primary and secondary motor cortices.
abstract: Rodents have primary and secondary motor cortices that are involved in the execution of voluntary movements via their direct and parallel projections to the spinal cord. However, it is unclear whether the rodent secondary motor cortex has any motor function distinct from the primary motor cortex to properly control voluntary movements. In the present study, we quantitatively examined neuronal activity in the caudal forelimb area (CFA) of the primary motor cortex and rostral forelimb area (RFA) of the secondary motor cortex in head-fixed rats performing forelimb movements (pushing, holding, and pulling a lever). We found virtually no major differences between CFA and RFA neurons, regardless of neuron subtypes, not only in their basal spiking properties but also in the time-course, amplitude, and direction preference of their functional activation for simple forelimb movements. However, the RFA neurons, as compared with the CFA neurons, showed obviously a greater susceptibility of their functional activation to an alteration in a behavioral situation, a 'rewarding' response that leads to reward or a 'consummatory' response that follows reward water, which might be accompanied by some internal adaptations without affecting the motor outputs. Our results suggest that, although the CFA and RFA neurons commonly process fundamental motor information to properly control forelimb movements, the RFA neurons may be functionally differentiated to integrate motor information with internal state information for an adaptation to goal-directed behaviors.
authors.affiliation: Brain Science Institute, Tamagawa University, Machida, Tokyo, Japan; Graduate School of Brain Sciences, Tamagawa University, Machida, Tokyo, Japan; JST CREST, Chiyoda-ku, Tokyo, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Saiki
authors.affiliation: Brain Science Institute, Tamagawa University, Machida, Tokyo, Japan; JST CREST, Chiyoda-ku, Tokyo, Japan.
authors.forename: Rie
authors.initials: R
authors.lastname: Kimura
authors.affiliation: Brain Science Institute, Tamagawa University, Machida, Tokyo, Japan; Department of Applied Molecular Bioscience, Graduate School of Medicine, Yamaguchi University, Ube, Yamaguchi, Japan.
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Samura
authors.affiliation: Brain Science Institute, Tamagawa University, Machida, Tokyo, Japan; JST CREST, Chiyoda-ku, Tokyo, Japan; Laboratory of Neural Circuitry, Graduate School of Brain Science, Doshisha University, Kizugawa, Kyoto, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Fujiwara-Tsukamoto
authors.affiliation: Brain Science Institute, Tamagawa University, Machida, Tokyo, Japan; Graduate School of Brain Sciences, Tamagawa University, Machida, Tokyo, Japan; JST CREST, Chiyoda-ku, Tokyo, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Sakai
authors.affiliation: Brain Science Institute, Tamagawa University, Machida, Tokyo, Japan; Graduate School of Brain Sciences, Tamagawa University, Machida, Tokyo, Japan; JST CREST, Chiyoda-ku, Tokyo, Japan.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Isomura
mesh_terms: D000818:Animals; D004594:Electrophysiology; D005552:Forelimb / Q000502:physiology; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D051381:Rats