“Slacker” rat brains are programmed to choose an easy life
“Hard work is its own reward,” according to some killjoys, but if you just can’t see the logic in the sentiment it’s possible that your brain is just wired differently. Results of a new study, unveiled today at the 2018 Canadian Neuroscience Meeting in Vancouver, show that some rats take the easy route not because they’re inherently lazier/smarter (pick your own editorial line) – but because their brains are programmed to do so.
The University of British Columbia’s research shows that certain regions of the brain are closely correlated with rodent decision making, and whether to put in more effort for a big reward, or less for a more modest prize. As you might expect, there’s not a single ‘decision making’ part of the brain – rather there’s a whole system of brain regions that juggle the risk, reward and effort required.
“Our research shows that decision-making relies on brain regions involved in emotional responses (the basolateral amygdala) and translating those emotions into actions (striatal and dopamine systems) but also regions of frontal cortex (the anterior cingulate and medial prefrontal cortices) which are involved in detecting causal relationships between events, and evaluating outcomes,” explained Dr Catharine Winstanley, lead author on the study.
I know what you’re thinking: how do you identify when a rat is phoning it in? Winstanley and her team devised a rat cognitive effort task which awarded rodents with a sugary pellet for poking their nose through a correct hole, identified by a light which briefly appeared above it. There were two difficulty modes, which the rats picked by pressing one of two levers: the first flashed the light for one second, while the other only flicked on for a fifth of the time, making it far harder to spot. To incentivise rats pushing their rodent reflexes to the limit, flicking the second lever would result in double the reward.
The researchers found that some rats routinely picked the easy test (affectionately labelled “slackers” by the team), while others showed a preference for the hard mode (“workers”). Intriguingly, that preference didn’t correlate with the skill or efficiency rodents demonstrated in the rat equivalent of Deal or No Deal. Rather, through selective inactivation, the team found that it correlated to the areas listed above.
That’s interesting, but why were the researchers looking at rat industry? Largely because many human psychiatric disorders are associated with the decision making process from bipolar mania and psychopathy all the way to drug and alcohol addictions. Having a better idea of what impacts decision-making processes could give us a real insight into new treatment methods.
We also know that in humans going for the hard but more rewarding options can have a huge impact on life chances. Indeed infants that perform well in the marshmallow test tend to have more successful adulthoods.
“The degree to which we are willing to select options that require more cognitive effort but which have the potential to lead to greater rewards has far-reaching consequences for our economic and personal success,” Winstanley said. “The availability of a large range of behavioural tests in animals can help decipher the key players in the brain, in terms of brain regions and chemical signals, that are involved in making these decisions.
“Understanding how the brain makes decisions is one of the most fundamental questions in neuroscience today.”