Abstract
The interplay between two major forebrain structures - cortex and subcortical striatum - is critical for flexible, goal-directed action. Traditionally, it has been proposed that striatum is critical for selecting what type of action is initiated while the primary motor cortex is involved in the online control of movement execution. Recent data indicates that striatum may also be critical for specifying movement execution. These alternatives have been difficult to reconcile because when comparing very distinct actions, as in the vast majority of work to date, they make essentially indistinguishable predictions. Here, we develop quantitative models to reveal a somewhat paradoxical insight: only comparing neural activity during similar actions makes strongly distinguishing predictions. We thus developed a novel reach-to-pull task in which mice reliably selected between two similar, but distinct reach targets and pull forces. Simultaneous cortical and subcortical recordings were uniquely consistent with a model in which cortex and striatum jointly specify flexible parameters of action during movement execution.
One sentence summary Motor cortex and subcortical striatum act in concert to specify the movement parameters of a reach-to-pull action in mice.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
1 Quantitatively, the active ensembles must be less correlated than the ensembles in the input as in (28). In many accounts, including (28), the representations proposed are only static patterns associated with an action (e.g. (13, 28)); however, this is clearly inconsistent with the complex temporal dynamics of dSTR (and MOp) activity during movement (32, 34, 39). Thus, to ‘steelman’ the selection model we entertain a stronger version including temporal dynamics (6).
2 Dimensions of activity other than leading PCs provide a robust encoding of continuous parameters; later we consider how to find such activity dimensions in the case of a specification encoding model.
