How basal ganglia do sequence control

Research Neuroscience
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Another brilliant piece of research out of Henry Yin’s lab.

Striatal Pathways for Action Counting and Steering.
Isabella P. Fallon, Marina Roshchina, Feiyang Hong, Sofia Fernandez, Shaolin Ruan, Henry H. Yin.
doi: https://doi.org/10.1101/2025.11.02.686102
URL: https://www.biorxiv.org/content/10.1101/2025.11.02.686102v1.full.pdf+html

Excerpt from the Introduction (BG=Basal Ganglia):

Classic theories emphasize the BG’s role in action selection. According to this view, the BG selects a single action through the direct pathway while suppressing competing actions via the indirect pathway, to enable discrete choice between behavioral options. The details of each action (e.g., direction or speed) are assumed to be determined outside the BG. [PCT, by contrast, explains continuous control.] … These two views—categorical selection versus continuous control—have often been treated as mutually exclusive, yet it is possible that BG output may unify both processes by representation [of] progress toward specific behavioral goals. … Indeed previous studies have shown that the dorsolateral striatum (DLS) contributes … both [to] the initiation and execution of action sequences and to the continuous pursuit of spatial goals. Given these results, it is possible that BG circuits compute internal variables, such as elapsed time or number of completed actions, that help organisms determine when to transition from one phase of behavior to the next.

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This sounds great! I just wrote to Henry for a reprint.

You quote this from the intro to the paper:

Given these results, it is possible that BG circuits compute internal variables, such as elapsed time or number of completed actions, that help organisms determine when to transition from one phase of behavior to the next.

This suggests that the “internal variables” that are computed by the BG are perceptual variables – sequence perceptions – that are being controlled via the “transitions” (equivalent to variations) in the “phases of behavior” that are “determined” (again equivalent to varied) by their effect (as well as those of external disturbances) on those internal variables (more precisely, by the difference between the state of the internal – perceptual - variable and the reference specification for the state of that variable. Anyway, I look forward to see how the authors of the article think those neural circuits work.