title: Distinct cortical circuit mechanisms for complex forelimb movement and motor map topography.
abstract: Cortical motor maps are the basis of voluntary movement, but they have proven difficult to understand in the context of their underlying neuronal circuits. We applied light-based motor mapping of Channelrhodopsin-2 mice to reveal a functional subdivision of the forelimb motor cortex based on the direction of movement evoked by brief (10 ms) pulses. Prolonged trains of electrical or optogenetic stimulation (100-500 ms) targeted to anterior or posterior subregions of motor cortex evoked reproducible complex movements of the forelimb to distinct positions in space. Blocking excitatory cortical synaptic transmission did not abolish basic motor map topography, but the site-specific expression of complex movements was lost. Our data suggest that the topography of movement maps arises from their segregated output projections, whereas complex movements evoked by prolonged stimulation require intracortical synaptic transmission.
authors.affiliation: Department of Psychiatry, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Harrison
authors.forename: Oliver G S
authors.initials: OG
authors.lastname: Ayling
authors.forename: Timothy H
authors.initials: TH
authors.lastname: Murphy
mesh_terms: D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D001703:Biophysics; D001931:Brain Mapping; D000697:Central Nervous System Stimulants / Q000494:pharmacology; D000075402:Channelrhodopsins; D016291:Dizocilpine Maleate / Q000494:pharmacology; D004558:Electric Stimulation; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000187:drug effects / Q000502:physiology*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005552:Forelimb / Q000502:physiology*; D018756:GABA Antagonists / Q000494:pharmacology; D049452:Green Fluorescent Proteins / Q000235:genetics; D008027:Light; D008164:Luminescent Proteins / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D009044:Motor Cortex / Q000187:drug effects / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D009415:Nerve Net / Q000187:drug effects / Q000502:physiology; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology; D055095:Optics and Photonics; D010852:Picrotoxin / Q000494:pharmacology; D011724:Pyridazines / Q000494:pharmacology; D011930:Reaction Time; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D018800:Thy-1 Antigens / Q000235:genetics; D014161:Transduction, Genetic / Q000379:methods; D014741:Video Recording; D014851:Wakefulness / Q000502:physiology
chemical_list: D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D001426:Bacterial Proteins; D000697:Central Nervous System Stimulants; D000075402:Channelrhodopsins; D016291:Dizocilpine Maleate; D018691:Excitatory Amino Acid Antagonists; D018756:GABA Antagonists; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D010852:Picrotoxin; D011724:Pyridazines; D018800:Thy-1 Antigens; C054562:yellow fluorescent protein, Bacteria; C049853:gabazine