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Timing, movement, and reward contributions to prefrontal and striatal ramping activity
Journal article   Peer reviewed

Timing, movement, and reward contributions to prefrontal and striatal ramping activity

Alexandra Bova, Matthew A Weber, Mackenzie M Spicer, Vaibhav Khandelwal, Rachael A Volkman, Madison McMurrin, Julia Kryca, Kartik Sivakumar, Braedon Q Kirkpatrick, Qiang Zhang, …
The Journal of neuroscience, Vol.46(21), e1493252026
05/27/2026
DOI: 10.1523/JNEUROSCI.1493-25.2026
PMCID: PMC13217530
PMID: 41997872

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Abstract

Across species, prefrontal and striatal neurons exhibit time-dependent ramping activity, defined as a consistent monotonic change in firing rate across temporal intervals. However, it is unclear if ramping activity is related to the cognitive process of estimating time, or to other behavioral factors such as anticipating reward or regulating movements. Here, we harnessed two novel approaches to determine how these factors contribute to prefrontal and striatal ramping activity in male and female mice performing an interval timing task. First, to determine how movement contributes to ramping activity, we tracked movement velocity using DeepLabCut as well as task-specific movements while recording prefrontal or striatal ensembles during interval timing. We found that time was more accurately decoded by ramping neurons than movement-modulated neurons, with the exception of prefrontal velocity-modulated neurons. Second, to disambiguate temporal signals from anticipatory reward signals we compared activity patterns in neurons that were recorded during interval timing to the same neurons recorded during a Pavlovian conditioning task. We found more ramping activity and more accurate temporal decoding by neuronal ensembles during interval timing compared to Pavlovian conditioning. Together, these data quantify contributions of time estimation, movement, and reward anticipation in prefrontal and striatal ensembles, and they suggest that ramping is a cognitive signal that estimates time. Our results provide insight into how prefrontal and striatal ensembles multiplex information to effect temporal control of action. Time is an essential dimension of behavior, and temporal control of action is disrupted in brain diseases, yet it is unclear how neurons encode time. In cognitive areas such as prefrontal cortex and dorsomedial striatum, neurons encode time via 'ramping', or monotonic changes across a temporal interval. However, ramping might be affected by movements or anticipating upcoming rewards. To quantify time-related, movement-related, and reward-related contributions to ramping, we tracked movement as mice performed interval timing and Pavlovian conditioning tasks. While we found prominent movement-related and reward-related activity, neither fully accounted for ramping activity, and ramping activity exhibited stronger temporal decoding than other neuronal patterns of activity. These results support an active role for prefrontal and striatal ramping in time estimation.

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