Cake on the Brain

I love cake.

I mean, I really love cake. I exist in a constant battle between my desire for its delicious spongy goodness, and for maintaining a healthy BMI.

So of course, when considering what I would write about for my next blog post, cake was on my mind.

On my mind? Cake on my mind – that’s cake on the brain – that’s cake and neuroscience! Hurrah! I can write about cake!

It turned out that this was easier said than done. A quick google of ‘brain’ and ‘cake’ turned up a huge range of impressively brain-shaped desserts, but that wasn’t quite what I was after. So I turned to a database of scientific publications – a tool I typically use during my working day with precise and sensible search parameters to discover the latest work on a very specific topic. Not this time! I repeated my ‘cake’ and ‘brain’ search, and here are three things that I found:

 

  1. Oreos are practically Cocaine

Well, sort of. But not really. Oreos aren’t my delicious treat of choice, but it turns out that rats are pretty keen on them. A study identified which rats had a strong preference for Oreos and those that didn’t. They then compared how much cocaine either group of rats gave to themselves.

Now, rats that take cocaine aren’t dropped into a seedy nightclub, and don’t have teeny tiny credit cards or rolled up notes. Instead, a small tube (cannula) is implanted into their brain and is attached to a small pump. Whenever the rat presses a lever, this pump releases a controlled dose of cocaine through the tube and into their brain. The rats rather like this, and will learn that pressing the lever = getting high.

It turns out that the rats that loved the Oreos were also pretty darn keen on the coke. While both groups of rats learnt to press the lever, the Oreo-rats were slower to stop pressing it when the cocaine reward was stopped, and were much more enthusiastic in their pressing when the drug was reinstated. The study also found that presenting the rats with an Oreo before their stint in the coke-box temporarily boosted their lever pressing.

There was no such effect when rats were given rice cakes instead of biscuits (sorry, my American friends – ‘cookies’).

Oreo cartoon1

This suggests that Oreos (or any other delicious treat) are likely to work on the same pathways in our brains as drugs do – namely, those associated with motivation and reward. When we eat something delicious, we feel good due to the activation of ‘reward pathways’ in our brain – this feeling reinforces that behaviour so we are likely to do it again to get back that good feeling. Drugs hijack the same pathways. So when rats have a strong preference for Oreos, they may be more sensitive to how rewarding they are. This then makes them vulnerable to doing other things that will give a similar rewarding feeling. Such as cocaine.

It’s important to bear in mind, that although drugs and Oreos roughly use the same pathways of reward and motivation in our brains, they have vastly different effects on cells, addiction and health.

Take cake, not coke.

 

  1. Having that ice cream now will ruin your dessert.

…At least how much you enjoy it. In the previous section, I mentioned the brain’s reward pathway. Part of this pathway is regulated by Dopamine – a chemical released in the brain that transmits signals between cells (A.K.A a Neurotransmitter). Increased Dopamine signalling in the brain typically means something good has happened and you are being rewarded for it with some good feelings. So in the previous example, Oreos/drugs = lots of dopamine release. Much of this dopamine activity occurs in an area of the brain called the Striatum.

Another group of researchers gave people an fMRI scan (functional magnetic resonance imagingthis is a way of measuring which areas of the brain are most active, based on the level of oxygen-rich blood being delivered to those areas) while they were given either an ice-cream based milkshake, or an ever-so-appetising ‘tasteless wash’ to drink. Having a delicious creamy milkshake fed to you through a tube whilst lying in a big magnetic cylinder was apparently rewarding, and there was increased activation of the striatum in the people that drank the milkshake.

*However* The extent of the activation was lower in people that regularly ate ice cream, meaning that their experience of drinking a milkshake felt much less rewarding and just not as good. The implication is that repeated eating of a particular type of food will reduce the Dopamine response in your Striatum, possibly leading to overeating of that foodstuff to try and get the same great feeling as the first time it touched your tongue.

So I must hold back on the cake, or I just won’t appreciate it as much.

 

  1. Cavemen are responsible for ruining your diet

That’s enough about reward, we know eating delicious cake makes us happy, that’s why it’s described as delicious! I’ve never heard the phrases ‘delicious rice cake’ or ‘delicious tasteless wash.’

So how about cake and attention?

It has previously been shown that when people are hungry, they are more likely to pay attention to food-related words, and to recall more food-related items in a memory test. A study in 2010 used a test called the ‘Emotional Blink of Attention (EBA).’ This is based on a test where people are told to look out for a particular image (or ‘Target’), such as a landscape scene, while they are shown several different images in quick succession. However, if another image that is likely to provoke an emotional response is shown immediately before the target image they are looking out for, then they will pay more attention to the emotional image and will be less likely to notice the target that is shown immediately after. Images causing EBA have typically been related to violence, gore or sex.

Cake cartoon1

When people were hungry, the EBA effect was seen when a picture of cake was shown immediately before the target image. This was even the case when people were offered a monetary reward to ignore the pictures of food. They just couldn’t help paying attention to the cake!

Being able to automatically pay attention to food-related things when hungry is likely to be something that helped our ancestors adapt to their environment and be successful at hunting and staying alive. Now, however, food-related things are everywhere, but this survival response remains. That has big consequences for dieters who are frequently hungry – being hungry means you are more likely to notice that vending machine, the café over there and the charity cake sale a couple of floors up at work. Couple this with an urge for a tasty Dopamine response and now it makes sense why sticking to a diet can be so tough!

So basically – cake is like a drug that we just can’t ignore. So why fight it? Have a slice – just not too often!

 

The Biocheminist

 

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