**Summary: **Researchers exploring risky decision-making in rats found that a specific reward-related neural circuit influences impulsivity and risk-taking in complex ways that depend on timing and biological sex. Manipulating the circuit during the learning phase of a gambling task altered risky choices differently in males and females, while manipulation after learning affected motor impulsivity in both.

These results reveal that the same brain system can guide distinct behaviors depending on when it’s engaged. The study suggests that effective treatments for impulsivity-related disorders may need to account for both sex differences and a person’s stage of behavioral learning.

Key Facts

• Timing Matters: Manipulating the same neural circuit before or after learning influenced risk and impulsivity differently.
• Sex Differences: Reward-related neurons affected risky decision-making uniquely in male and female rats.
• Clinical Implication: Findings highlight why tailored, sex-specific, and stage-dependent treatments are key for impulsivity disorders.

**Source: **SfN

**Some people with psychiatric conditions, including addiction and attention deficit hyperactivity disorder, struggle to control their urges or make decisions under uncertainty. **

In a collaboration between the University of Cambridge and the University of British Columbia, Tristan Hynes and colleagues used rats to explore the role of a specific reward-related neuron population in shaping impulsivity and risky decision-making during a gambling task.

As reported in their Journal of Neuroscience paper, the researchers manipulated the neuron population’s activity as rats chose between four holes associated with different probabilities of receiving a reward or a time-out punishment.

Influencing neuron activity as rats learned the task affected risky decision-making differently in males and females. But when the researchers manipulated neuron activity after the rats had already learned the task, this selectively affected motor impulsivity in both sexes.

In other words, the same neural circuit drove entirely different aspects of behavior depending on timing and sex.

Says Hynes, “These findings underscore that neural circuits don’t operate in isolation or uniformly across individuals; they shift their influence depending on sex and experience.

“So, a one-size-fits-all approach to pharmacotherapy won’t cut it: both where someone is in the progression of their disorder and their biological sex can change how the underlying brain circuitry responds to treatment.”

Key Questions Answered:

Q: What brain system was studied in this research?

A: A reward-related neural circuit that influences decision-making under risk.

Q: How did timing affect behavior?

A: Manipulation during learning altered risky decisions, while post-learning changes affected impulsivity control.

Q: Why does this matter for mental health treatment?

A: Because impulsivity and risk-taking rely on flexible brain circuits that respond differently across sex and experience, individualized therapy is essential.

About this neuroscience research news

**Author: **SfN Media **Source: **SfN **Contact: **SfN Media – SfN **Image: **The image is credited to Neuroscience News

**Original Research: **Closed access. “Ventral Striatal Cholinergic Interneurons Regulate Decision-Making or Motor Impulsivity Differentially Across Learning and Biological Sex” by Tristan Hynes et al. Journal of Neuroscience

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Abstract

Ventral Striatal Cholinergic Interneurons Regulate Decision-Making or Motor Impulsivity Differentially Across Learning and Biological Sex

Dopaminergic transmission within the ventral striatum is broadly implicated in risk/reward decision making and impulse control, and the rat gambling task (rGT) measures both behaviours concurrently.

While the resulting indices of risky choice and impulsivity correlate at the population level, dopaminergic manipulations rarely impact both behaviours uniformly, with changes in choice more likely when dopaminergic transmission is altered during task acquisition.

Although the task structure of the rGT remains constant, the relative importance of ventral striatal dopamine signals relevant for reward prediction versus impulse control may vary as learning progresses; the former should dominate while rats learn the probabilistic contingencies of the task, whereas suppression of premature responses becomes more valuable once a decision-making strategy is established and exploited.

Striatal cholinergic interneurons (CINs) critically influence reinforcement learning by modulating dopamine release and gating periods of dopamine-facilitated neuroplasticity. We therefore hypothesised that ventral striatal CINs (vsCINs) could influence reward learning or impulse control during task acquisition or stable performance, respectively.

Using chemogenetics in Sprague Dawley rats (Rattus norvegicus), we found support for this hypothesis: activation and inhibition of vsCINs once behaviour was stable increased and decreased motor impulsivity in both sexes but had no effect on choice patterns.

In contrast, activating and inhibiting vsCINs during task acquisition did not alter motor impulsivity but instead decreased and increased risky choice, respectively. Notably, the former effect was only observed in males, and the latter in females.

We conclude by proposing testable predictions regarding acetylcholine–dopamine interactions that may explain sex differences.