title: Neural antecedents of self-initiated actions in secondary motor cortex.
abstract: The neural origins of spontaneous or self-initiated actions are not well understood and their interpretation is controversial. To address these issues, we used a task in which rats decide when to abort waiting for a delayed tone. We recorded neurons in the secondary motor cortex (M2) and interpreted our findings in light of an integration-to-bound decision model. A first population of M2 neurons ramped to a constant threshold at rates proportional to waiting time, strongly resembling integrator output. A second population, which we propose provide input to the integrator, fired in sequences and showed trial-to-trial rate fluctuations correlated with waiting times. An integration model fit to these data also quantitatively predicted the observed inter-neuronal correlations. Together, these results reinforce the generality of the integration-to-bound model of decision-making. These models identify the initial intention to act as the moment of threshold crossing while explaining how antecedent subthreshold neural activity can influence an action without implying a decision.
authors.affiliation: Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown, Lisbon, Portugal.
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Murakami
authors.affiliation: Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown, Lisbon, Portugal.
authors.forename: M Inês
authors.initials: MI
authors.lastname: Vicente
authors.affiliation: Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown, Lisbon, Portugal.
authors.forename: Gil M
authors.initials: GM
authors.lastname: Costa
authors.affiliation: Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown, Lisbon, Portugal.
authors.forename: Zachary F
authors.initials: ZF
authors.lastname: Mainen
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D003657:Decision Making / Q000502:physiology; D008297:Male; D008959:Models, Neurological; D009044:Motor Cortex / Q000502:physiology*; D009415:Nerve Net / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D020318:Rats, Long-Evans; D011930:Reaction Time; D012054:Reinforcement, Psychology