Sub-second Dopamine and Serotonin Signaling in Human Striatum during Perceptual Decision-Making.
Level 4 - case-series / case-control
Small observational human case series with invasive neurochemical recordings
PubMed 33049201 · doi:10.1016/j.neuron.2020.09.015
What was done
Researchers monitored sub-second dopamine and serotonin signaling in the human striatum during a visual motion discrimination task designed to separate sensory uncertainty from decision difficulty using a factorial structure. Invasive neurochemical recordings were collected from the caudate nucleus (n = 4) and the putamen (n = 1) while participants performed the task.
What was found
The abstract reports qualitative observations without numerical effect sizes or p-values. In the caudate nucleus (n = 4), serotonin tracked sensory uncertainty in 3 participants, while both dopamine and serotonin tracked deviations from expected trial transitions in 1 participant. In the putamen (n = 1), both dopamine and serotonin tracked decision times.
Why it matters
This study provides direct, sub-second evidence in humans that dopamine and serotonin signal dimensions of sensory inference, uncertainty, and action timing beyond classical reward-based cognition.
Limits
The total sample size is extremely small (n = 5 across two separate brain targets). No quantitative effect sizes, variance, or statistical test metrics are provided in the abstract. Findings were heterogeneous across participants, and results from patients undergoing invasive brain recording may not generalize to healthy populations.