title: The ventral tegmental area modulates intracortical microstimulation (ICMS)-evoked M1 activity in a time-dependent manner.
abstract: Intracortical microstimulation (ICMS)-evoked neural activity combined with ventral tegmental area (VTA) stimulation was studied in rat primary motor cortex (M1). We used voltage-sensitive dye (VSD) imaging to analyze the spatiotemporal dynamics of M1 activity following VTA-M1 paired stimulation. VTA stimulation was preceded by M1 ICMS at inter-stimulus intervals (ISIs) of 15-350ms. VSD imaging showed an excitatory-inhibitory sequence of neural activity after composing VTA stimulus- and ICMS-induced M1 neural activity. To evaluate the net ICMS M1 response, the optical response to unpaired VTA stimulation was subtracted from the VTA-M1 paired response. This revealed that the net ICMS-evoked M1 neural activity was inhibited when the ISI was 30-50ms, but highly facilitated when the ISI was 100-350ms. These results suggest that VTA modulates M1 excitability in the order of tens to hundreds of milliseconds and might directly affect the motor command generation process in the M1.
authors.affiliation: Human Informatics Research Institute, National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba 305-8568, Japan; Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8577, Japan; RIKEN Brain Science Institute, 2-1 Hirosawa, Wako 351-0198, Japan.
authors.forename: Nobuo
authors.initials: N
authors.lastname: Kunori
authors.affiliation: Department of Electronics and Bioinformatics, Meiji University, Tama, Kawasaki 214-8571, Japan.
authors.forename: Riichi
authors.initials: R
authors.lastname: Kajiwara
authors.affiliation: Human Informatics Research Institute, National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba 305-8568, Japan; Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8577, Japan. Electronic address: i.takashima@aist.go.jp.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Takashima
mesh_terms: D000818:Animals; D001921:Brain / Q000502:physiology*; D004558:Electric Stimulation; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D017208:Rats, Wistar; D013681:Tegmentum Mesencephali / Q000502:physiology*; D013997:Time Factors; D056969:Voltage-Sensitive Dye Imaging
keywords: Intracortical microstimulation; Primary motor cortex; Ventral tegmental area; Voltage-sensitive dye imaging