Seeing the bigger picture

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 its importance and value to your future. Neuromodulators are chemicals that influence how a neuron responds to other neurons, and today we will discuss three of them; acetylcholine, dopamine, and serotonin.

Acetylcholine

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.

Dopamine

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.

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.

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.

Serotonine

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.

Amygdala

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.

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