title: Learning-dependent potentiation in the vibrissal motor cortex is closely related to the acquisition of conditioned whisker responses in behaving mice.
abstract: The role of the primary motor cortex in the acquisition of new motor skills was evaluated during classical conditioning of vibrissal protraction responses in behaving mice, using a trace paradigm. Conditioned stimulus (CS) presentation elicited a characteristic field potential in the vibrissal motor cortex, which was dependent on the synchronized firing of layer V pyramidal cells. CS-evoked and other event-related potentials were particular cases of a motor cortex oscillatory state related to the increased firing of pyramidal neurons and to vibrissal activities. Along conditioning sessions, but not during pseudoconditioning, CS-evoked field potentials and unitary pyramidal cell responses grew with a time-course similar to the percentage of vibrissal conditioned responses (CRs), and correlated significantly with CR parameters. High-frequency stimulation of barrel cortex afferents to the vibrissal motor cortex mimicked CS-related potentials growth, suggesting that the latter process was due to a learning-dependent potentiation of cortico-cortical synaptic inputs. This potentiation seemed to enhance the efficiency of cortical commands to whisker-pad intrinsic muscles, enabling the generation of acquired motor responses.
authors.affiliation: División de Neurociencias, Universidad Pablo de Olavide, 41013-Sevilla, Spain;
authors.forename: Julieta
authors.initials: J
authors.lastname: Troncoso
authors.forename: Alejandro
authors.initials: A
authors.lastname: Múnera
authors.forename: José María
authors.initials: JM
authors.lastname: Delgado-García