title: Thalamocortical Projections onto Behaviorally Relevant Neurons Exhibit Plasticity during Adult Motor Learning.
abstract: Layer 5 neurons of the neocortex receive direct and relatively strong input from the thalamus. However, the intralaminar distribution of these inputs and their capacity for plasticity in adult animals are largely unknown. In slices of the primary motor cortex (M1), we simultaneously recorded from pairs of corticospinal neurons associated with control of distinct motor outputs: distal forelimb versus proximal forelimb. Activation of ChR2-expressing thalamocortical afferents in M1 before motor learning produced equivalent responses in monosynaptic excitation of neurons controlling the distal and proximal forelimb, suggesting balanced thalamic input at baseline. Following skilled grasp training, however, thalamocortical input shifted to bias activation of corticospinal neurons associated with control of the distal forelimb. This increase was associated with a cell-specific increase in mEPSC amplitude but not presynaptic release probability. These findings demonstrate distinct and highly segregated plasticity of thalamocortical projections during adult learning.
authors.affiliation: Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093.
authors.forename: Jeremy S
authors.initials: JS
authors.lastname: Biane
authors.affiliation: Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Takashima
authors.affiliation: Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093; Department of Neurobiology, University of California, San Diego, La Jolla, CA 92093; Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093.
authors.forename: Massimo
authors.initials: M
authors.lastname: Scanziani
authors.affiliation: Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093.
authors.forename: James M
authors.initials: JM
authors.lastname: Conner
authors.affiliation: Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093; Veterans Affairs Medical Center, San Diego, CA 92161. Electronic address: mtuszynski@ucsd.edu.
authors.forename: Mark H
authors.initials: MH
authors.lastname: Tuszynski
mesh_terms: D000818:Animals; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D000075402:Channelrhodopsins; D016291:Dizocilpine Maleate / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D005552:Forelimb / Q000502:physiology; D007858:Learning / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009044:Motor Cortex / Q000166:cytology / Q000502:physiology*; D009048:Motor Skills / Q000187:drug effects / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology; D009434:Neural Pathways / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D011916:Rats, Inbred F344; D011930:Reaction Time / Q000187:drug effects; D013788:Thalamus / Q000166:cytology / Q000502:physiology*; D014161:Transduction, Genetic
chemical_list: D002135:Calcium-Binding Proteins; C581829:Camk2n1 protein, rat; D002352:Carrier Proteins; D000075402:Channelrhodopsins; D018691:Excitatory Amino Acid Antagonists; D011810:Quinoxalines; C056723:FG 9041; D016291:Dizocilpine Maleate