15 April 2011,

Although much is still unknown about the brain, one thing that is certain is that there is one big neural highway that links the back of the brain, to the front. No big surprises yet. What is interesting, is that this hormonal highway explains basically all feelings of pleasure. It is called the Mesolimbic Dopamine reward path or the brain reward pathway. This hormonal highway (or, ˊneural circuitˊ) is driven by Dopamine and Serotonin. The rush of serotonin and dopamine that we experience when we eat, sleep, or… copulate…feels so good that we psychologists have made a name for it, it’s called ˊPrimary Reinforcementˊ.

So, these primary triggers for the brain (sleep, drink, eat, sex) are the primary triggers of the brain reward pathway. Why? Because all of these behaviours help us to survive. Think about any single one of those things- try living without it for a week.
…See what I mean?

Critically, there are series of secondary reinforcers – and this is where the ‘brain and overeating’ connection might spark some personal enlightenment. We’’re not just sensitive to primary rewards, but also the paired associations we make prior to experiencing those rewards. Think of the bell and Pavlov, and you’’ll catch my drift.

The anticipation of winning the lottery can trigger the Brain Reward Pathway. Pornography triggers the BRP. Pictures of food – especially high calorie, high fat food – triggers the BRP. Something crazy? Obviously, we are not just super sensitive to pictures, but rather to the substances that elicit that feeling of desire. Tobacco and sugar both cross the blood brain barrier and directly triggers dopamine release. Quitting smoking is like quitting eating, which is why it’s so tough— hold on a minute— sugar crosses the blood brain barrier?! Like tobacco?

So, does this mean that all of the rules that we have learned about cigarettes apply to food too? Maybe.

We take for granted that we don’’t see cigarette advertisements, that we don’’t debate about ‘cigarettes every now and then… well, everything in moderation’, that we all chuckle knowingly at episodes of Mad Men thinking about the olden days when doctors gave their advice about smoking Camels to enhance athletic performance. We accept that the small short lived pleasure associated with smoking is likely not ˊˊworth itˊˊ.

…Yet some how with food we are still debating the merits of including highly palatable, high sugar high fat food in our diet? And then searching around to blame the obesity crisis on things like MSG or even aspartame? Chemicals are not to blame for obesity – or at least, theyˊre not the root cause. Fat and Sugar and Salt (and get this, ingestion of these constitutes as an act of Primary Reinforcement!) are what is to blame.
Now it’’s my turn to scare you, in a nutshell, food that is heavily laden with sugar/ fat/ salt was never supposed to be a part of our diet. I am not saying ‘chemicals’ nor ‘additivies’ nor ‘preservatives’, simply that fat + sugar/ salt is a lethal combination. I do mean lethal: ask one of the millions of people suffering with a BMI of 50 how they deal with ˊeating in moderationˊ. Hereˊs a brief defense of why highly palatable food could be considered ˊˊaddictiveˊˊ.
– sugar crosses the blood brain barrier
– can elicit the same kind of seeking behaviour you see in drug addicts,
– and worse yet, overeating causes severe depression

So, if our brains havenˊt evolved to compensate and deal with the new environmental changes imposed by the Candy Land we now live in, how can we expect our bodies to miraculously respond either?

More on this next week… Let me know your thoughts on the posts…

6 responses on “The Brain Reward Pathway

  1. FH says:

    Hi, I really felt this post strike a cord with what Iˊm going through at the moment. Iˊve anorexia and bulimia. Maybe not entirely anorexic but because Iˊve a low BMI of 15 Iˊm classified as that as well. But Iˊve been steadily gaining weight because of the bulimia and it makes me feel very depressed. I feel like Iˊm addicted to bingeing and couldnˊt recover because I donˊt know what to stop the urges to binge. After reading your post, I think it must be because the reward pathway is stimulated every time I binge and purge so every time I feel depressed I will have to urge to binge to make myself feel better. I also tend to eat a lot of chocolates and keep them down because I buy good quality chocolate to ˊrewardˊ myself after a long week of uni and I feel bad if I purge them out. Is there any way I can break this cycle of food stimulating the reward pathway? Thanks

  2. Addy says:

    Stay with this guys, youˊre hlepnig a lot of people.

  3. Heidi says:

    Most help articles on the web are icncaurtae or incoherent. Not this!

  4. I really like your wordpress theme, where did you get a hold of it from?

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