Imagine approaching a food buffet, you have your eye on a pizza but at the last second you spot the steak and quickly shift one onto your plate.
Your ability to make a split-second decision could be powered by dopamine, researchers have discovered.
Scientists studying the behaviour of mice found that the brain chemical significantly affects your chances of making a snap movement or decision.
Source: Daily Mail
Their discovery could help people who have problems controlling their movements, including those suffering from Parkinson’s disease and obsessive compulsive disorder (OCD).
Dopamine is a neurotransmitter that is known to play a role in how our brains derives pleasure from activities such as gambling and sex, as well as addiction.
Now researchers from Salk Institute of Biological Sciences in San Diego have found that the chemical could also shape our decisions.
They discovered that dopamine governs snap choices so precisely that measuring the brain chemical level right before a decision is made allows researchers to accurately predict the outcome.
The scientists also found that changing the dopamine level of a mouse is enough to alter what decision it will make.
‘Because we cannot do more than one thing at a time, the brain is constantly making decisions about what to do next,’ said Professor Xin Jin, an assistant professor at Salk’s Molecular Neurobiology Laboratory.
‘In most cases our brain controls these decisions at a higher level than talking directly to particular muscles, and that is what my lab mostly wants to understand better.’
Researchers designed an experiment in which mice were forced to make a snap decision in order to win a treat.
The mice had to choose between pressing one of two levers in a middle of a custom-built chamber, with the treat dispenser in the middle.
The levers retracted from the chamber at the start of each trial and reappeared after either two seconds or eight seconds.
The mice quickly learned that when the levers reappeared after the shorter time, pressing the left lever yielded a treat.
When they reappeared after the longer time, pressing the right lever resulted in a treat.
This design represented a simplified two-choice situation for the mice.
They moved to the left side of the chamber initially, but if the levers didn’t reappear within a certain amount of time, the mice chose to shift to the right side.
‘This particular design allows us to ask a unique question about what happens in the brain during this mental and physical switch from one choice to another,’ said Dr Hao Li, a researcher at the Salk Institute.
As the mice performed the trials, the researchers used a technique called fast-scan cyclic voltammetry to measure dopamine concentration in the animals’ brains via embedded electrodes finer than a human hair.
The technique allows for extremely frequent measurements and can pick up rapid changes in brain chemistry.
The voltammetry results showed that fluctuations in brain dopamine level were tightly associated with the animal’s decision.
To verify that dopamine level caused the choice change, rather than just being associated with it, the team used molecular engineering.
The researchers used a technique called optogenetics, that uses beams of light, to manipulate the animals’ brain dopamine levels in real time.
They found they were able to manipulate the mice to move from one lever to the other just by increasing or decreasing dopamine levels.
Professor Jin said: ‘We think that if we could restore the appropriate dopamine dynamics in Parkinson’s disease, OCD and drug addiction, people might have better control of their behaviour.
‘This is an important step in understanding how to accomplish that.’
The research was published in the journal Neuron.