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TitleDistinct cortical circuit mechanisms for complex forelimb movement and motor map topography.
Publication TypeJournal Article
Year of Publication2012
AuthorsHarrison, Thomas C., Oliver G. S. Ayling, and Timothy H. Murphy
Date Published2012 Apr 26
Keywords6-Cyano-7-nitroquinoxaline-2,3-dione, Analysis of Variance, Animals, Antigens, Thy-1, Bacterial Proteins, Biophysics, Brain Mapping, Central Nervous System Stimulants, Dizocilpine Maleate, Electric Stimulation, Electromyography, Evoked Potentials, Motor, Excitatory Amino Acid Antagonists, Forelimb, GABA Antagonists, Green Fluorescent Proteins, Light, Luminescent Proteins, Mice, Mice, Transgenic, Motor Cortex, Movement, Nerve Net, Neural Pathways, Optics and Photonics, Picrotoxin, Pyridazines, Reaction Time, Rhodopsin, Synaptic Transmission, Transduction, Genetic, Video Recording, Wakefulness

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.

Alternate JournalNeuron
PubMed ID22542191
Grant ListMOP-12675 / / Canadian Institutes of Health Research / Canada