Anticipation and Dopamine

Robert Sapolsky is a neuroscientist who studies dopamine in the brain. He trained monkeys to know that when a light comes on that is a signal. The monkeys knew that if they pressed a button 10 times, after the signal, then on the tenth button press, a food treat would appear.

Sapolsky measured the amount and timing of dopamine release in the monkeys’ brains during the cycle of signal — work (pressing the button) — reward (food treat). The monkeys received the treat as soon as they pressed the bar 10 times. Surprisingly, the dopamine release started as soon as the signal arrived, and ended at the end of the bar pressing.

Many people think that dopamine is released when the brain receives a reward, but dopamine is actually released in anticipation of a reward. It’s the dopamine that keeps the monkey pressing the bar until the treat arrives.

In a second experiment, the monkeys received the food treat only 50 percent of the time after they pressed the bar. What happened to the dopamine in that situation? Twice as much dopamine was released when there was only a 50/50 chance of getting the food treat.

In the third and fourth experiments, Sapolsky gave the treat 25 percent of the time or 75 percent of the time. Interestingly, when the treat was given either 25 percent of the time or 75 percent of the time, the dopamine release was the same, and it was halfway between the 100 percent and 50 percent chance of getting a food treat.

Unpredictability increases anticipation

When the monkeys got the treat all the time, a fair amount of dopamine was released during the pressing phase. When getting the treat was unpredictable, the amount of dopamine went up. In the 25 and 75 percent situations, there was actually more predictability. If the monkey got a food treat 25 percent of the time, it meant that they mostly didn’t get one. If they got a food treat 75 percent of the time, it meant that they mostly got one. Getting the food treat 50 percent of the time was the least predictable situation.

Importance of dopamine

Dopamine plays an important role in:-
1. Learning
2. Motivation
3. Mood
4. Attention
5. Movement