Fievel was a lab rat with an altered brain. In a series of experiments performed by James Olds and Peter Milner at McGill University in the 1950s, Fievel and his lab mates had electrodes implanted in their nucleus accumbens, which is a part of the basal forebrain, deep within the skull.
Finding Happiness in the Science Lab
At certain corners within a box, the rats discovered that they would get an electric jolt to their brain. Depending on where in the brain the electrodes were implanted, the rats either hated or enjoyed getting shocked.
When the rats were given a lever to administer shocks to themselves, they hit the lever incessantly. Jolting their own nucleus accumbens became so fantastically addictive that the rats forgot to eat and had to be nursed to stay alive.
Based on this behavior, Olds and Milner believed they had discovered the brain’s pleasure center in the nucleus accumbens, along with dopamine as a key neurotransmitter of good feelings.
Pleasure and Neuroscience
Scientists now believe that the brain’s pleasure receptors operate like a communication web. The nucleus accumbens is still important, but it works in concert with many other parts of the brain to form the pleasure circuit.
Once activated, the VTA churns out dopamine, a chemical messenger, which in turn fires up several other areas, including the nucleus accumbens, septum, amygdala, and prefrontal cortex.
Each part performs a function. The nucleus accumbens engages our motor functions while the prefrontal cortex focuses our attention.
The amygdala conditions our response to stimuli, encouraging us to repeat gratifying actions.
The orbitofrontal cortex, which sits just above our eyes, gives us a feeling of gratification, and slowly dials the feeling down when the sensation has reached a limit.
Memories of satisfaction are formed by the hippocampus.
All of these players work together to help us feel pleasure and motivate us to pursue it again.
This process also responds to endorphins, which are stress-relieving chemicals.
Certain areas of the brain that respond strongly to endorphins are called “hedonic hot spots”, and they work in tandem with the pleasure circuit.
Dopamine, sometimes called the brain’s “pleasure chemical,” is an important messenger in the pleasure circuit that is now thought to be a motivation booster rather than a feel-good signal. In other words, dopamine creates desire.
When dopamine is suppressed in rats, they stop wanting to eat. Lack of motivation is a symptom of depression, and dopamine has recently been studied in relation to depression in humans.
Leading and Misleading the Brain to be Happy
Beyond pleasure circuits and dopamine, scientists agree that the brain’s interpretation of pleasure is complex, and not easily reduced to cells and chemicals.
The concept of pleasure is nebulous, encompassing desire, action, and satisfaction. There are simple sensory pleasures like the taste of sweetness, and higher pleasures like the enjoyment of art and learning.
Pleasure is linked to happiness, which reaches into the fuzzy realm of meaning and belief, all of which are a tough match for neuroscience.
What is known, though, is that craving and pleasure are registered deep within the brain, in the vicinity of instincts and reflexes.
Even in our biology, therefore, pleasure is basic. We naturally seek pleasure, and it’s part of our biological toolkit for survival. That’s why life functions like eating and procreating can be so much fun.
Pleasure gives us cues for life, and behavior in turn teaches our brain.
When we feel pleasure, it re-wires our brain for future action. So, when pleasure circuits are abused – for example, through drug abuse – it’s extremely hard to correct.
Normally, pleasure circuits are activated by natural triggers like hunger or fatigue, but addictive substances kick start our pleasure circuits directly, causing positive reinforcements in our brains that drive us to repeat the high.
And brains are more gullible than you may think. Even without drugs or alcohol, our brains can be tricked into experiencing more pleasure, with just a few words.
Experiments have found that people enjoy the same wine more if you tell them that it’s the expensive stuff.
People’s perception of how beautiful someone is changes depending on what information they are given; that is, we find people more attractive when we also like them.
Our pleasure responses fluctuate. We enjoy some things the first time, but get tired of them later. Think songs by Taylor Swift. On the flipside, we find some painful things pleasurable, like Thai massage.
When it comes to pleasure, biology tells only part of the story. Brain cells help us experience pleasure, but figuring it out is a knotty matter that is more convoluted than brain tissue, itself.
“How Addiction Hijacks the Brain.” Havard Health Publications. Retrieved September 7, 2015.
Kringelbach, Morten L. and Berridge, Kent C. “The Functional Neuroanatomy of Pleasure and Happiness.” Discovery Medicine. June 2010.
Kringelbach, Morten L. and Berridge, Kent C. “The Joyful Mind.” Scientific American. August 2012.
Kringelbach, Morten L. and Berridge, Kent C. “The Neuroscience of Happiness and Pleasure.” Social Research. Summer 2010.
“Pleasure and Pain.” The Brain From Top to Bottom. McGill University. Retrieved September 7, 2015.