If you spend any time reading brain and behavior studies, you will find plenty of references to “pleasure centers” lighting up in response to all kinds of behaviors.  But what exactly is a pleasure center and how does it affect human behavior?

Eureka!

Most of what we know about the brain’s pleasure center is taken from a 1956 study published in Scientific American. The research pinpointed the nucleus accumbens in the brain as a key factor in causing pleasurable sensations.  Since then, scores of studies have continued to fill in the blanks about the brain’s response to pleasurable stimuli.

SLIDESHOW: Your brain on sex

What we can now say with certainty is that the ‘pleasure center’ is a catch-all term for several different areas of the brain that are intricately connected, but unique  with regard to their purpose and function.  For example, certain areas of the brain are involved in feelings of satiation while others control motivation and emotion.  For the sake of simplicity, we will focus on two systems within the brain that are central to the feelings of motivation and reward.

Defining the territory   

Nucleus accumbens – The nucleus accumbens is a collection of neurons that forms a major part of the ventral striatum.

Ventral tegmental area (VTA) – the VTA is located in the mid-brain at the top of the brainstem and works in tandem with the nucleus accumbens to release dopamine – the neurotransmitter that promotes desire in response to stimuli.

Dopamine – a chemical messenger (neurotransmitter). 

How it works

For any species to survive and thrive it must be able to carry out certain vital functions.  For example, it must nourish itself, procreate, and respond to aggression or defend itself.

So, when the body does something that is vital to its survival, such as eating or having sex,  the VTA receives information that this activity is in progress and forwards that message to the nucleus accumbens in the form of dopamine.  The nucleus accumbens regulates the release of dopamine causing the body to feel motivated to complete a pleasurable activity.

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As a result, when you do things that are necessary to survival, the brain works to help you feel good while you’re doing them and motivate you to do them again.

Addiction: A disordered rewards system

This process, however,  can become disordered like any other system in the body.  For example, while eating is good and necessary for survival, there are limits on how much one should eat in a day.  The brain also has ways of making us feel satiated to avoid overindulging in certain actions even if they are vital to survival.

Addictions – such as addictions to food, alcohol, sex and so on – can be a result of an over-stimulated rewards system that leaves a person unable to resist the strong triggers to indulge in those behaviors.