The prospect of a reward usually motivates us to perform better, but a particularly big one can have the opposite effect – like losing at a penalty shoot-out. Now, researchers have identified a potential brain mechanism that may cause us to choke under pressure.
In 2021, at Carnegie Mellon University, Pennsylvania, and his colleagues showed that . The researchers trained three rhesus monkeys to perform a difficult reaching task in return for a reward – sugary water – and found that they performed worst when the reward was most plentiful.
To better understand why this happens, the same researchers trained a different group of rhesus monkeys to reach for a small moving target, which required fast and accurate movements, in exchange for different quantities of sugary water. They used microelectrodes to record the activity of neurons in the animals’ motor cortex, the brain region that plans and executes movements.
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The team found that individual cells in this region were sensitive to the size of the expected reward and “tuned” their responses accordingly – increasing their activity in anticipation of larger rewards and decreasing it when they expected smaller ones.
When looking at the coordinated activity of the region’s cells, the researchers also found neural “signatures” for planned movements, with each of the monkeys’ upcoming reaches being associated with a distinct pattern of neural activity that corresponded to planning the execution of the movement.
But when the monkeys expected a jackpot reward, the difference between the signatures for each planned reach movement decreased dramatically. The movement planning information that was encoded in the cell population broke down, making the patterns that were associated with each possible movement harder to distinguish from one another.
This suggests that reward-related information interacts with the formation of motor command signals in the motor cortex, say the researchers.
The anticipation of a reward therefore appears to boost our motor planning so that we execute the best possible movement to achieve this prize, but the expectation of a huge reward seems to interfere with this process, making it harder to select the best motor command. Consequently, the movement may not be prepared, or executed, as well as it could be.
Why this occurs, however, is unclear. “We’d really love to find out if it’s the dopamine [a neurotransmitter involved in pleasurable rewards and motivation] system going haywire that throws the motor cortex off balance at the key moment,” says study author  at the University of Pittsburgh, Pennsylvania.
The researchers expect that a similar neurological mechanism occurs in people. “Monkeys choke under pressure in ways similar to how humans do, and the cerebral cortices of monkeys and humans are similar,” says Batista.
With further research, the results may point to ways that we could one day warn people if they may be about to underperform while stressed, he says. “It is tantalising to think that if we could eventually find some signature of [choking under pressure using] mobile imaging, we could inform people of whether or not they are likely to choke,” says Batista.
bioRxiv
