By Keerthi Lakshmi Narayanan
~5-minute read
There’s always that one friend who’s the first to propose a spontaneous night drive in the group chat, who’s down for any adventure, no matter the time, date, or place. And then there’s the yin to their yang, who responds to that same proposal with four follow-up questions and a 2 page argument against the idea. Somehow, you end up going anyway, dragged along by the treacherous group consensus, while the second friend details every possible thing that could go wrong the entire car drive.
This is usually explained away with personality talk- one of the friends is just “spontaneous” and “adventure-loving,” and the other is “just anxious”, but what’s actually going on has less to do with who’s a party animal and who’s a party pooper and more to do with two brain systems that are running on different clocks.
The ventral striatum is a deceptively small structure buried in the depths of your brain, and is the ‘first responder’ of your reward system. The instant that something promising shows up, like a good deal, an unexpectedly high score, this part of your brain reacts first. On the other hand, the prefrontal cortex that sits right behind your forehead works on a much slower timeline by gathering information, running the odds, and checking for a catch before it lets you commit to anything. Risk-based decision-making relies on the coordination between different brain regions, as the prefrontal cortex handles big-picture thinking while the striatum pushes you towards reward. (Zhao et al.,2025)
In more impulsive brains, the connection between the reward system and prefrontal cortex tends to be relatively weaker, so the signal advising towards patience and weighing the consequences before the decision takes more time to arrive, and by the time it has, you’re already halfway up the cliff. To put it in layman’s terms, impulsive brains have brakes too, but the accelerator always beats it to the race.
On the other hand, cautious decision-makers’ brains have been proven to have increased levels of activity in a particular region of the prefrontal cortex called the dorsolateral prefrontal cortex, which acts as the control center for self-control. When researchers experimentally increased this area’s activity up or down, people’s willingness to take a gamble on uncertain outcomes shifted with it. (Wagner et al., 2022) Differences in your brain’s fronto-striatal wiring have been directly linked to how impulsive someone tends to be. (Kaur & Sohal, 2025)
Dopamine is usually blamed for impulsivity, but the link between risk-taking and dopamine is closer related to the availability of your body’s dopamine receptors rather than the amount of dopamine you have in your body. Lower availability of a specific kind of dopamine receptor has been tied to greater risk-taking. (Gianaros et al., 2015)
It’s important to remember that this doesn’t make one type of brain better than the other. Impulsive brains are the reason some people make the leap into founding a company nobody else believed in, or making the split-second call that can win a game. Cautious brains are the reason surgeons don’t rush a procedure, scientists triple-check their data before publishing, and some people never end up with a regrettable tattoo from 2 am on a whim. Every functional group project needs both kinds of people in it.
This wiring in your brain isn’t permanent either- during adolescence, the reward-driven systems in your brain mature much faster than the regulatory prefrontal systems, and this mismatch, amplified by a surge in dopamine activity, is a large part of why teenagers tend to run more impulsively than adults do. This gap narrows gradually as the prefrontal cortex keeps developing into your mid-twenties, which is also why the friend proposing spontaneous night drives at 17 isn’t guaranteed to be the same person at 30.
Written by Keerthi Lakshmi Narayanan, published by Viktoriia Dmitrieva.
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Sources:
Zhao, Y., et al. (2025). Neural mechanisms of maladaptive risk decision-making across psychiatric disorders. Frontiers in Behavioral Neuroscience. https://www.frontiersin.org/journals/behavioral-neuroscience/articles/10.3389/fnbeh.2025.1637582/full
Kaur, G., & Sohal, V. S. (2025). Ventral Striatal Cholinergic Interneurons Regulate Decision-Making or Motor Impulsivity Differentially across Learning and Biological Sex. Journal of Neuroscience. https://www.jneurosci.org/content/45/49/e0764252025
Wagner, B., et al. (2022). Dorsolateral prefrontal cortex plays causal role in probability weighting during risky choice. Scientific Reports. https://www.nature.com/articles/s41598-022-18529-6
Gianaros, P. J., et al. (2015). Functional Genetic Variation in Dopamine Signaling Moderates Prefrontal Cortical Activity During Risky Decision Making. Neuropsychopharmacology. https://www.nature.com/articles/npp2015192
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