What Motivates You?

Welcome back.

It is hard to learn when you’re not into it.

But if it’s something you’re really interested in, learning is easy.

Why is that?

Most of the neurons in your cortex carry information about what is happening around you and what you’re doing.

Your brain also has a set of diffusely projecting systems of neuromodulators, that carry information not about the content of an experience but it’s importance and value to your future, neuromodulators are chemicals that influence how a neurons responds to other neurons.

And today we will discuss three of them.

Acetylcholine, dopamine and serotonin.

Acetylcholine neurons form neuromodulatory connections to the cortex that are particularly important for focused learning, when you are paying close attention.

These acetylcholine neurons project widely and activate circuits that control synaptic plasticity.

Leading to new long term memory.

Neuromodulators also have a profound impact on your unconscious mind.

One of the great brain discoveries in my lifetime has been that our motivation is controlled by a particular chemical substance called Dopamine.

Which is found in a small set of neurons in our brain stem shown here in orange.

These dopamine neurons are part of a large brain system that controls reward learning and in particular in the basal ganglia which is located in the green region above the dopamine neurons and below the cortex at the top of the brain.

Dopamine is released from these neurons, when we receive an unexpected reward.

Dopamine signals project widely and have a very powerful effect on learning.

And this is something that also affects decision making.

And even the value of sensory inputs.

Dopamine is in the business of predicting future rewards and not just the immediate reward.

This can motivate you to do something that may not be rewarding right now but will lead to a much better reward in the future.

Addictive drugs artificially increase dopamine activity and fool your brain into thinking that something wonderful has just happened.

In fact just the opposite has just happened.

This leads to craving and dependence, which can hijack your free will and can motivate actions that are harmful to you.

Loss of Dopamine neurons leads to a lack of motivation.

And something called anhedonia, which is a loss of interest in things that once gave you pleasure.

Severe loss of Dopamine neurons causes resting tremor, slowness, rigidity, this is called Parkinson’s disease.

Ultimately it leads to catatonia, a complete lack of any movement.

Dopamine neurons are part of the unconscious part of your brain.

That you learned about in the first week.

When you promise to treat yourself something after a study section you are tapping into your dopamine system.

Serotonin is a third diffuse neuromodulatory system that strongly affects your social life.

In monkey troops the alpha male has the highest level of serotonin activity and the lowest ranking male has the lowest levels.

Prozac, which is prescribed for clinical depression, raises the level of Serotonin activity.

The level of Serotonin is also closely linked to risk taking behavior.

With higher risk in lower Serotonin monkeys.

Inmates in jail for violent crimes have some of the lowest levels of serotonin activity in society.

Finally your emotions strongly affect learning as you are well aware.

Emotions were once thought to be separate from cognition but recent research has shown that emotions are intertwined with perception and attention and interact with learning and memory.

The amygdala an almond shaped structure shown here, nestled down at the base of the brain is one of the major centers where cognition and emotion are effectively integrated.

The amygdala is part of the limbic system which together with hippocampus is involved in processing memory and decision making as well as regulating emotional reactions.

You will want to keep your amygdala happy to be an effective learner.

The emotions and your neuromodulatory systems are slower than perception and action but are no less important for successful learning.

If you want to learn more about Acetylcholine, Dopamine, and Serotonin, look them on brainfacts.org.

A website that is filled with valuable facts about your brain.

I’m Terry Sejnowski.

Happy learning, until we meet again.