Oct 29, 2020 20:00:00

There is a possibility that motivation can be regained by identifying and activating the circuit of the brain that causes 'the motivation to learn decreases as we get older'.

As people grow older, they lose the motivation to learn new things. A research team at the Massachusetts Institute of Technology (MIT) has identified brain circuits that play an important role in reducing motivation in experiments with mice. The research team has confirmed that activating this circuit increases motivation for learning in mice, and suppressing it decreases motivation.

Striosomes Mediate Value-Based Learning Vulnerable in Age and a Huntington's Disease Model: Cell

https://www.cell.com/cell/fulltext/S0092-8674 (20) 31301-5

Study helps explain why motivation to learn declines with age | MIT News | Massachusetts Institute of Technology
https://news.mit.edu/2020/why-learn-motivate-age-decline-1027

The striatum, which is part of the basal ganglia , which is responsible for various functions such as motor regulation, cognitive function, emotion, and motivation, is thought to be involved in decision making. Ann Graybiel, a MIT neuroscientist, has been studying the circuit called 'striosomes' in the striatum for many years, and now it is clear that striosomes are greatly involved in learning motivation.

Since striosomes are deep in the brain, they are difficult to detect by fMRI and are still a mystery. However, Griviel and colleagues have discovered in the past that striosomes play an important role in the decision-making of 'approach-avoidant conflict.' 'Approach-avoidant conflict' is a conflict that occurs between positive and negative desires such as 'I want to eat sweets but I don't want to gain weight', and I think it causes great anxiety for people. Has been done.

Grivier has already announced in previous studies that striosomes are connected to the dopaminergic

substantia nigra, and many researchers have said that 'striosomes provide emotional information and sensations from the cortex. Perhaps we are making action decisions by absorbing them and integrating them. ' Later, in 2017, Grivier conducted a mouse experiment, studying that stressed mice are more likely to make high-risk, high-return decisions, while mice that manipulate the striosome circuit do not make such decisions. The results are also shown.

And in a new study, Grivier observed and analyzed how striosomes work when mice learn decisions that produce positive and negative results.

In this experiment, we heard two types of mouse sounds. The first sound was associated with the reward of 'sugar water', and the second sound was associated with the disgust of 'bright light'. Every time the experiment is repeated, the mouse 'gets a lot of sugar water when the first sound is heard while licking the water spout' and 'if you do not lick the spout when the second sound is flowing' I gradually learned that the light becomes weaker.

This type of learning requires a 'cost' and 'reward' assessment. Researchers found that when mice were learning, striosomes were more active than the circuits present in other striatum, and that this activity was also associated with mouse behavior for the two sounds. From this, we thought that striosomes were important for 'assigning subjective value to specific results.'

Researchers have also observed that older mice, which are 13 to 21 months old and are 60 years of age or older, have less learning effort that requires cost and reward analysis. In addition, we found that older mice had less striosome activity than younger mice, and that mice with Huntington's disease with degenerated striatum had similar motivation reductions.

However, even in elderly mice, when researchers administer drugs and stimulate striosomes, they are able to tackle more tasks. On the contrary, it has been confirmed that when the activity of striosome is suppressed, the mouse stops working on the task.

In addition to common aging, many mental health disorders can distort human reward and cost assessments, researchers say. For this reason, researchers are working on the development of drug treatments that improve the condition by strengthening the activity of the circuit discovered this time.

'Patients may be able to properly activate their circuits if they can identify the mechanisms that make subjective assessments of rewards and costs and manipulate them with modern technologies such as psychological or biofeedback .' Researchers say.