title: Voltage-sensitive dye imaging of primary motor cortex activity produced by ventral tegmental area stimulation.
abstract: The primary motor cortex (M1) receives dopaminergic projections from the ventral tegmental area (VTA) through the mesocortical dopamine pathway. However, few studies have focused on changes in M1 neuronal activity caused by VTA activation. To address this issue, we used voltage-sensitive dye imaging (VSD) to reveal the spatiotemporal dynamics of M1 activity induced by single-pulse stimulation of VTA in anesthetized rats. VSD imaging showed that brief electrical stimulation of unilateral VTA elicited a short-latency excitatory-inhibitory sequence of neuronal activity not only in the ipsilateral but also in the contralateral M1. The contralateral M1 response was not affected by pharmacological blockade of ipsilateral M1 activity, but it was completely abolished by corpus callosum transection. Although the VTA-evoked neuronal activity extended throughout the entire M1, we found the most prominent activity in the forelimb area of M1. The 6-OHDA-lesioned VTA failed to evoke M1 activity. Furthermore, both excitatory and inhibitory intact VTA-induced activity was entirely extinguished by blocking glutamate receptors in the target M1. When intracortical microstimulation of M1 was paired with VTA stimulation, the evoked forelimb muscle activity was facilitated or inhibited, depending on the interval between the two stimuli. These findings suggest that VTA neurons directly modulate the excitability of M1 neurons via fast glutamate signaling and, consequently, may control the last cortical stage of motor command processing.
authors: Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba 305-8577, Japan, Human Technology Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8568, Japan.
authors: Nobuo
authors: N
authors: Kunori
authors: Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8566, Japan, and Department of Electronics and Bioinformatics, Meiji University, Tama, Kawasaki 214-8571, Japan.
authors: Riichi
authors: R
authors: Kajiwara
authors: Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba 305-8577, Japan, Human Technology Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8568, Japan, i.takashima@aist.go.jp.
authors: Ichiro
authors: http://orcid.org/0000-0003-0272-5075
authors: I
authors: Takashima
mesh_terms: D000818:Animals; D059290:Dopaminergic Neurons / Q000187:drug effects / Q000502:physiology; D008297:Male; D009044:Motor Cortex / Q000187:drug effects / Q000502:physiology*; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D016627:Oxidopamine / Q000633:toxicity; D051381:Rats; D017208:Rats, Wistar; D017557:Ventral Tegmental Area / Q000187:drug effects / Q000502:physiology*; D056969:Voltage-Sensitive Dye Imaging
chemical_list: D016627:Oxidopamine
keywords: electromyogram; intracortical microstimulation; mesocortical projection; motor learning; optical imaging; reward signaling