You may be thinking, did I read the title right or is she
just making up words? No, you’re right; the nucleus accumbens is an actual area in the brain (proof below).
As you (may) know, last week I talked about how heroin can pass through the blood brain barrier, but what I did not mention is how we can easily become addicted to drugs. You're probably thinking everyone knows that, but today I want to talk about the role the nucleus accumbens and dopamine plays in addiction.
So to begin with, what is addiction? I know when most people hear addiction they think junkies, rehab, habit, druggies, homeless, unstable, etc,. However, addiction is simply the repetition of a behavior despite the potentially harmful consequences. It has to do with intense cravings and even loss of control in the user. It can "rewire" the brain by changing our motivations and reinforcing drug experiences and decreasing or inhibiting the pleasure of other experiences. Basically it makes the experiences caused by the drug more alluring, leaving other actions unable to compete for the attention.
Back to the nucleus accumbens
It is an area rich in dopamine, which is one neurotransmitter responsible for stimulating pleasure centers in the brain and transmitting impulses from neurons to the brain. The nucleus accumbens is also responsible for reinforcing all kinds of experiences we find rewarding as well as in learning new behaviors. It is why it is so“addicting” or rewarding to get high. All drugs of abuse stimulate the nucleus accumbens by releasing dopamine in the nucleus accumbens. Therefore, when the brain releases this neurotransmitter the "high" felt becomes associated with the drug, reinforcing the usage. Once the user experiences this high, this memory becomes imprinted as a memory in the hippocampus and is brought back to "memory" every time someone craves, thinks, or takes the drug. Whether the drug usage will lead to addiction depends on many factors such as:
Dopamine
- speed of release
- amount released
- intensity of release
- route of administration (injection, inhalation, intranasal, ingestion...)
- dosage
- genetic susceptibility
- frequency of usage
Here is a video explaining the pathology of addiction (it is a little lengthy so I recommend starting at 2:43). I think this video does a good job in explaining how the nucleus accumbens, dopamine, and serotonin play a role in addiction.
A quick word about tolerance
Tolerance is when more of the drug is needed for the user to experience the same effects and happens when the user habitually uses. Habitual use of the drug leads our brain to adapt and make the effects of the drug less pleasurable or stimulating. When our brain adapts, dopamine has less effect on the nucleus accumbens and we need more and more every time.
Disclosure
Do not think that drugs are the only thing you can become addicted or that stimulate the pleasure centers in the brain!
References:
Kalat, James. Biolgical Psychology: Eleventh Edition
http://www.wisegeek.com/what-is-the-nucleus-accumbens.htm
http://addiction-dirkh.blogspot.com/2010/02/nucleus-accumbens.html
http://www.helpguide.org/harvard/addiction_hijacks_brain.htm
Hello Alejandra. I really enjoyed your blog this week. I learned a lot of new things that i had not realized before. A new thing to me was the reason of our addictions. I had no idea that the nucleus accumbens was responsible for feeling pleasure. Something that was really interesting to me was to find out that having a hypersensitive nucleus accumbens can lead to addiction. Not only does dopamine play a big role but so does serotonin. Serotonin is in charge of telling us when we have had enough of that particular thing. Drug and alcohol addicts must have very deficient serotonin since they can never have enough. I liked how the video used the two figures and the beer as an example. It made it very simple for me to understand.
ReplyDeleteI enjoyed reading your blog, I felt when you stated, "addiction is simply the repetition of a behavior despite the potentially harmful consequences. It has to do with intense cravings and even loss of control in the user. It can "rewire" the brain by changing our motivations and reinforcing drug experiences and decreasing or inhibiting the pleasure of other experiences. Basically it makes the experiences caused by the drug more alluring, leaving other actions unable to compete for the attention." it really helped give a brief and precise meaning to addiction.
ReplyDeleteGreat blog post. It was really informative and I got a lot out of it then I hadn't previously thought about. I found your disclosure to be quite interesting. When you hear about addiction, 9 times out of 10 drugs or alcohol come into your mind, but that's just not the full story, and I liked how you brought that out. There are many things that we can become addicted to because of their effect on stimulating our pleasure centers, and I'm really glad that you pointed that out.
ReplyDeleteAlejandra I love how you made your blog not only informative, but always kept it interesting enough for me to keep on reading and wanting to know more about how the nucleus accumbens plays a role in addiction. Your visuals were great and remained objective at all points. Above all, I found your topic to be very educative on how addiction can take place and how addiction depends on factors such as: the speed of release and amount of dopamine intake. The video was also great in explaining the pathology of addiction.
ReplyDelete