Neural antecedents of self-initiated actions in secondary motor cortex

Murakami, Masayoshi; Vicente, M Inês; Costa, Gil M; Mainen, Zachary F

http://hdl.handle.net/10400.26/23196

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Murakami et al., 2014, NatNeurosci.pdf		1.47 MB	Adobe PDF	Ver/Abrir

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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.