Wanting Is Different From Liking
The second major brain change that contributes to addiction has to do with cues. When there is a strengthening of the association between sugar and sugar related cues, this results in increased cravings. Addiction is characterized by having very strong cravings, and that can be to do with your drug of choice (sugar) or behaviours. It is also characterized by continuous compulsive eating despite negative consequences.
Cravings or wanting something is very different from liking something. Liking, occurs in the nucleus accumbans in the brain, and when the nucleus accumbans starts to become numb, liking, declines over time. I think you can notice this in any food choice. I like pizza, but I get bored of pizza if I eat pizza too often. That is a really good example of how my brain functions, by my nucleus accumbans becoming numb to my liking of pizza. However, if I was addicted to pizza, even though my liking would decline over time my wanting wouldn’t, my cravings for the pizza would instead increase, even though my pleasure derived from eating the pizza has declined.
So where do these overwhelming cravings come from?
The ventral tegmental area (VTA) of the brain is associated with reward prediction. The neurones in the VTA fire when a reward is unexpectedly received, releasing a chemical neurotransmitter called dopamine. Dopamine has been called the ‘addiction molecule’ and studies have shown that when addiction occurs there is a significant increase in dopamine. Dopamine release is associated with craving or wanting and this kind of craving or wanting is an impulsive urge, not a thoughtful long term goal. The incentive or the motivation or the wanting, becomes resilient and strong, and it is the dopamine that can intensifies that strong incentive. This is a primitive kind of wanting.
Repeated use of your food of choice leads to changes to the dopamine system that contributes to food addiction. The brain becomes sensitized, meaning that it becomes even more sensitive and easier to activate the sensitivity with the dopamine system responding more and more strongly to your foods of choice. This results in the cravings becoming stronger and stronger, for example; after eating the pizza a few times I feel some urge to eat it again, resulting in my dopamine system becoming sensitized with my craving for pizza becoming stronger and stronger, resulting in my urge to eat the pizza to be so strong that the need to eat another slice becomes virtually irresistible.
For those that are not addicted to pizza, they may eat the pizza a few times and may feel some urge to do it again, but those urges may not be particularly strong and so the urges can be easily resisted. As I talked about earlier, classical conditioning is based on learning from prediction errors, another change in the brain involves dopamine's effects on learning. If dopamine is the reward to prediction error, meaning that when the dopamine is released an unexpected reward had arrived or soon will arrive, it signals to us that we should pay attention so that we will be able to predict when such rewards might show up again! The release of dopamine signals that something important has happened. If I get my pizza, it triggers the release of dopamine, which also triggers learning, and if my pizza reward triggers larger than normal releases of dopamine, it also produces a particularly strong need for learning. The results of which is that what I have learned, is actually more harmful to me than helpful.
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