Scientists have found that the outcomes of actions in the brain can be properly evaluated, thanks to the fact that there are neurons in the brain.
The study was carried out in mice, but the researchers think it could apply to humans as well. Many previous studies have found a link between a part of the brain called the striatum and decisions that involve assessing outcomes.
The team looked at the neural activity associated with cost-benefit decisions, where an action can have a mix of both positive and negative outcomes. There is a balance of risk and reward in these options.
When a behavior leads to an outcome that isn't expected, the researchers were able to identify a particular group of neurons that became active during these decisions.
A lot of brain activity deals with surprising outcomes, because if an outcome is expected, there is nothing to be learned.
There is a strong encoding of both unexpected rewards and unexpected negative outcomes.
The mice were trained to spin a wheel in either direction. A positive outcome would be a drop of water and a negative outcome would be a small amount of air.
The mice learned to maximize the level of reward and minimize the amount of air puffs. The mice were forced to adjust their behavior because the researchers constantly shifted the probabilities of each outcome.
The striatum has steriosomes in red. Nature Communications, 2021, by Bloem et al.
The brain activity recorded in the striosomes differed depending on whether the actions were good or bad. The researchers noticed that many of the neurons in the brain are related to actions and outcomes.
When a wheel turn produced a different result than it had done before, stronger reactions were observed. The scientists thinkerror signals help the brain decide when to change its approach to a task.
Bloem says that the striosomes seem to mostly keep track of what the actual outcomes are.
There are messages sent to other parts of the brain that are linked to striosomes. They are related to decisions on whether or not to act.
It is easy to see how the process could go wrong as some of the decision neurons fire with both good and bad outcomes.
MIT neuroscientist Ann Graybiel says that our ability to make our movements or our thoughts in what we call a normal way depends on those distinctions.
This could be the cause of anxiety and depression, where slight disruptions in the neural networks identified by the researchers could result in impulsive decision-making at one end of the scale, and being paralyzed by indecision at the other.
Making decisions that are bad for us might be a result of our brains being confused about good and bad. Treatments for such conditions could eventually be improved by a greater understanding of how neural activity works.
The research could be useful in understanding the decisions we all make every day, like whether or not to eat ice cream instead of a healthier choice, as there is a short-term reward in terms of its sweetness, but a longer-term negative when it comes to weight.
The two outcomes can be considered equally good from a value perspective.
The striatum knows why these are good and what the cost is for each. In a way, the activity there shows more about the potential outcome than just how likely you are to choose it.
The research has been published.
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