Monthly Archives: October 2010

Beetrooccino & a certain xanthine alkaloid

Oh, caffeine. Or as its ultra-catchy IUPAC name would have it, 1,3,7-trimethyl-1H-purine-2,6(3H,7H)-dione. It’s the most widely consumed psychoactive substance in the world, and I’m consuming it right now, while I type! Just think of the things that have possibly been written under the influence of caffeine. Probably, like, War & Peace and stuff. And so this blog post pompously insinuates itself into that mighty company.

But how much of our dependence upon (and love affair with) caffeine is the result of its chemical effects on our brains, and how much is just in the mind? (Figuratively.)

It’s more than a little bit in the mind. You should know that by now.

One study had a little look at what happened to people’s ability to pay attention and detect important information after they consumed either a caffeinated or non-caffeinated drink, depending on whether they were told about its correct identity or misled (that’s right, another experiment full of blatant lies — I love it).

So all participants went through four sessions:

  • One in which they were given a caffeinated drink and told it was caffeinated (truth!).
  • One in which they were given a caffeinated drink and told it was non-caffeinated (lie!).
  • One in which they were given a non-caffeinated drink and told it was non-caffeinated (truth!).
  • One in which they were given a non-caffeinated drink and told it was caffeinated (lie!).

 
Different participants did the different sessions in different orders. They didn’t know that sometimes they were being lied to; they’re just drinking these drinks and then doing a computer task. So in each session, a little while after they consumed the drink, they performed a computer task in which numbers flashed up on the screen and participants had to pay attention and try to spot a target pattern (e.g. when the same number flashes up twice in a row and is an even number). This was a measure of their vigilance.

What would you expect would happen? We consume caffeine usually because we want to be more alert and pay attention, so having caffeine should improve vigilance, right? Well, yes, caffeine did improve vigilance.

But only when participants were told that their drink had caffeine in it.

If they had the caffeinated drink but were told it was decaffeinated, they performed pretty much exactly the same as when there really had been no caffeine in their drink. So their expectation that there was no caffeine to improve their performance meant that their performance wasn’t improved, even when the caffeine was there to act chemically on their brain.

However, this expectation effect wasn’t there for the non-caffeinated conditions: people performed pretty much equally after a non-caffeinated drink regardless of whether they thought it was caffeinated or not.

So what can we take away from this? Subtle relationships, people. Subtle relationships. It seems that there is an interaction between the chemical effects of caffeine and our normal expectations of what caffeine is going to do to us. The caffeine needs to be there, but we also need to expect it to be there and to work for it to actually work.

Or, more concisely, you can take this message away from it:

NEVER DOUBT YOUR CAFFEINE OR YOU WILL SUFFER THE CONSEQUENCES.

And with that in mind, fancy some beetroot coffee? Or as I call it… beetrooccino?

Yeah so this is pretty much inspired by Heston Blumenthal’s lobsterccino, but (1) I’m not aiming to emulate the crazy excess of the 1980s like Heston was (I wasn’t there for half that decade), (2) beetroot and coffee share odour compounds that might make them complement each other rather well and (3) I was buying molecular gastronomy supplies online and my order was under the minimum order value by 5 cents, so I bought a $4 packet of beetroot powder and had to figure out something to do with it.

And the beetrooccino is good. It is actually really good. The coffee and beetroot do complement each other very well, although I have to say it is rather a savoury drink. I wouldn’t want to finish a meal with this, but… it might work as a slightly crazy hors d’œuvre prior to food.

Read on for the recipe for beetrooccino…

Sweet sounds

These yuzu chocolate mud cakes with fizzy yuzu icing may be my favourite thing I’ve baked in a long time. The texture of the cakes is ridiculous (it’s kind of like peanut butter, in that it sticks to the roof of your mouth in a delightfully and irritatingly luxurious way). And yuzu, well, I currently pay $40 for a 300ml bottle of yuzu juice (weep!) but I’ve just tracked down Australia’s only yuzu grower, who just happens to be about a 2-hour drive south from here, so if I had a car I would probably be there right now (and possibly passed out amongst the rinds of the dozens of yuzu fruit I had gorged on) but I’ll have to wait a little longer until I can beg/borrow/win a car. Then… everything I cook will have yuzu in it.

Ev-er-y-thing.

Alright, so. Enough yuzu, more science.

Eating food is a multisensory experience. (Hurr durr derp derp that’s pretty obvious.) It’s all pretty damn important when it comes to the perception of food and the enjoyment of eating: the look, the smell, the taste, the texture. But who’s the lonely sense who’s been left out of the party? It’s hearing! Poor, neglected hearing. He wants to come to the party too. He wants to consort with the other senses with reckless abandon. Why won’t you let him? Why won’t you letttt himmmm?

We might not think much about hearing’s contribution to food (beyond the pleasing crunch of crunchy things — more on that in a future post) but it turns out that the brain doesn’t exclude hearing from the party completely. In fact, our brains make implicit associations between tastes and sounds. We might not be aware of them on a conscious level (is a sweet taste high-pitched or low-pitched?) but with the right sort of task, as provided by experimental psychology, we can get a look at the furtive, illicit dalliance between hearing and taste. How thrilling.

So the task is like this. You sit at a computer with your hands on the keyboard. Words are going to flash up one after another on the screen, and they’ll either be sweet words (words like sugar, honey, maple syrup) or salty words (words like salt, crisps, pretzel). Sometimes you’ll also hear sounds played over some headphones (2 seconds of sound played on an instrument such as a violin, piano or bassoon). The sounds will either be high-pitched or low-pitched. You and some other participants start off the experiment on Condition 1, then change to Condition 2 (while other participants will start on 2 and change to 1).

Condition 1
Press the A key if: you see a sweet word or hear a high-pitched tone.
Press the L key if: you see a salty word or hear a low-pitched tone.

Condition 2
Press the A key if: you see a sweet word or hear a low-pitched tone.
Press the L key if: you see a salty word or hear a high-pitched tone.

You as a participant probably won’t notice anything amazing during the experiment. But when the researchers look at your reaction times (i.e. how fast you were at pressing the correct key after you saw a word or heard a sound) they’ll notice something very interesting. You responded significantly faster in Condition 1 than in Condition 2.

For some reason, you’re faster when a sweet word and a high-pitched tone are associated (Condition 1) than when a sweet word and a low-pitched tone are associated (Condition 2). Likewise, you’re faster when a salty word and a low-pitched tone are associated (Condition 1) than when a salty word and a high-pitched tone are associated (Condition 2). Somehow, the sweet-high and salty-low combinations just make more sense to your brain, enabling you to react and identify them more quickly — and more accurately, since participants made fewer errors in Condition 1 (although the error rates in Condition 1 and 2 weren’t significantly different statistically).

Another study using the same kind of experiment found a significant association between sour words and high-pitched sounds, and between bitter words and low-pitched sounds. However, these researchers have also tested sweet, sour, salty and bitter altogether using a different task, and the pitch associations for salty and bitter disappeared, although the associations between sour words and high-pitched sounds and between sweet words and high-pitched sounds were still there. Hmm.

And it seems like we don’t really have a good explanation for why the brain does this. There are plenty of ways of drawing parallels between properties in different senses — for example, when comparing hearing to vision, the loudness of a sound might be thought of as the equivalent of the brightness of a colour, since increased loudness and increased brightness are both experienced by us as being more “intense”. So maybe we just don’t have a good enough grasp of the properties of taste to be able to figure out something like why sweet is somehow a parallel for high-pitched. Is there a biological basis to the association? Or is it cultural somehow? Do people from different cultures experience the same associations? Would the results be any different if actual tastes were used (e.g. a bit of sugar on the tongue) instead of taste-related words?

And… and… can we influence the perception of taste by using sound? If the basis of the association is biological, maybe closely connected or overlapping brain regions are responsible for sweet tastes and high pitches. There certainly is overlap between the hearing and taste sensory pathways, not just at later stages of cortical processing but in the early stages too, as the primary taste cortex (which I discussed in my previous post) is located partly in the insula, which also plays a pretty big role in auditory processing (Bamiou et al. 2003).

So it’s a big and tenuous jump, but… can we influence the perception of taste by using sound? If the association is due to neuronal connectivity, would something taste sweeter if we played high-pitched music compared to low-pitched music? Or would something just taste wrong somehow if sound that wasn’t associated with it was played? Intriguing possibilities…

Recipe for yuzu chocolate mud cakes with fizzy yuzu icing under the cut. Recommended serving suggestion: high-pitched sounds, naturellement.

Srs nurrosiense tiem

Have you ever been walking down the street when you stopped dead in your tracks and thought “OH GOD OH GOD HOW DO I TASTE THINGS?!! HOW DOES MY BRAIN LET ME TASTE SALTY PRETZELS UNNNGHHHH OH GOD I DON’T KNOW FFFFFFFFFFFFFWHAT DO I DO?”. I bet you have. I haven’t, but that’s because I do know (in a very rough approximation), although I imagine that if I didn’t know, I would be shrieking and my eyes would be bulging out of their sockets and I would possibly be convulsing in the middle of a road somewhere. Such is life.

So that’s it. It’s neuroscience time. None of this namby-pamby psychology stuff with people reading lists of words and acting ever so slightly differently as a result. We’re getting on a little nano-rocket and riding into the neuron metropolis. I’m a neuroscientist and I’m bringing my A-game. Are you? Yes? Is it folded up in your backpack? Ok.

Right then. After your tastebuds have detected food and the basic information about the food has been transmitted along nerves to the more fancy parts of the brain, what does the brain do? How do the actual neurons in the brain respond, and what sort of information do they respond to?

I’m going to concentrate on just one part of the brain for now – the primary taste cortex, consisting of sections called the insula and the frontal operculum. This primary taste cortex is place where the brain starts to integrate all the different bits of information about food. After this complex processing has begun, the primary taste cortex interacts with a huge range of other brain areas that are involved in the processing and perception of vision, smell and touch (not surprising, given the multisensory experience that is eating).

The other senses also have primary cortices where this sort of processing of sensory information goes on at a higher level, and taste perception shows some striking similarities to perception in the other senses.

For instance, in the primary visual cortex, there are neurons that only fire when you see very particular things. For example, there are neurons that fire in response to a vertical line in your field of vision (the side of house, a flagpole, etc) but don’t fire or decrease their firing below normal in response to a horizontal line (the horizon, the top of a desk, etc), and likewise, there are some neurons that only fire in response to horizontal lines and they’re not so responsive when presented with vertical lines. Neurons can be very specifically tuned and only respond to a very distinct stimulus, or they can be more general and fire in response to a range of stimuli. The same is the case in the primary taste cortex.

In the primary taste cortex, neurons respond to lots of different properties of food. Verhagen and colleagues looked at neurons in the primary taste cortex and how these neurons fired in response to food of varying taste, temperature, grittiness, viscosity and fat texture. They found that neurons can have a very specific profile of stimuli that they actually fire in response to.

Viscosity
53% of the neurons tested fired in response to the thickness or viscosity of food. When the researchers tested different viscosities (using carboxymethylcellulose), some neurons fired more in response to very thick consistencies whereas others fired in response to a runnier consistency.

Grittiness
8% of the neurons tested responded to grittiness as a consistency. So I guess these neurons will be firing like mad if you eat porridge with sand in it.

Fat
Another 8% of neurons tested actually responded to fat, but they identified fat by its texture, not by any chemical method. The researchers figured this out because the same neurons fired in response to non-fat oils that had the same texture as the fats tested.

Temperature
35% of neurons tested responded to the temperature of whatever was in the mouth. The researchers used water at different temperatures (10°C for a chilled drink, 42°C for a warm drink, 37°C for body temperature and 23°C for room temperature) and some neurons fired more in response to particular temperatures than others.

Capsaicin
6% of the neurons tested responded to capsaicin, the hot compound of chilli peppers. The interesting thing here is that these neurons didn’t respond to the warmest water temperature (42°C). So even though capsaicin is experienced as heat, it didn’t result in firing of the neurons that had fired to a warm liquid. However, it turns out that 42°C might have just been an unlucky temperature to choose as the upper limit in the experiment, as capsaicin’s hot effect is achieved through a particular type of receptor that only responds to temperatures greater than… 43°C. So if a hotter liquid had also been used in the experiment, then maybe neurons would have been found that fired in response to the hot liquid and capsaicin.

Taste
And of course, a fair few neurons responded to taste. 56% of neurons tested responded to taste, which was tested using blackcurrant juice (for sweetness), table salt (for saltiness), weak hydrochloric acid (for sourness), quinine (for bitterness) and MSG (for umami).

Now, these neurons didn’t always just fire preferentially for taste or temperature or viscosity or whatever — about half of them fired in response to combinations of these classes of stimuli. For example, 23% of them fired in response to both taste and temperature. A couple of them fired in response to taste and temperature and viscosity and fat. So there was overlap between the groups of neurons involved in responding to the different properties of the food, which allows for a much more complex and nuanced representation of food in the brain.

The interesting thing was that these neurons in the primary taste cortex did not fire in response to odor or the sight of food. This tells us that it isn’t until a later stage that taste information and visual and olfactory information get integrated. And that is indeed what the pathways of sensation in the brain tell us (as seen in the diagram below that I hastily knocked together). It’s rather complicated but hey, that’s the brain for you:

So don’t worry about understanding this whole mess (simply stand back and appreciate the complexity of that soft lumpy thing inside your skull). Just know that arrows indicate the flow of information, and blunt-ended lines indicate an inhibitory effect where the flow of information is dampened. And you can see that in the pink taste pathway, by the time information has gotten to the primary taste cortex from the taste receptors in the tongue, it hasn’t interacted with any of the other pathways. But in the next step, when information flows into the orbitofrontal cortex and amygdala, it has its first chance to interact with information from the other sensory modalities, vision (green), smell (gold) and touch (blue).

The orbitofrontal cortex is also the part of the brain responsible for the representation of the palatability and pleasantness of food, which means that how enjoyable food is probably results from an interplay of visual, taste, olfactory and touch factors. So no matter how delicious that pie tastes, if it happens to look like horse manure then the orbitofrontal cortex just isn’t going to assign as much of a pleasant experience to it.

So there you go. The basics of how the brain processes taste. But as is always the case, it’s a whole lot more complicated than that. When Verhagen and colleagues were looking at the firing properties of neurons in the primary taste cortex, they only reported on the neurons that responded to at least one of the stimuli in the experiment, whether it be a particular taste or viscosity, the presence of grittiness or fat, water of a particular temperature, and so on. In all, they tested 29 different stimuli to see if neurons fired in response. They found 62 neurons that did this. They found 1,060 that didn’t.

What are these other 1,060 neurons doing? What are the other hundreds of thousands of neurons that weren’t tested in the primary taste cortex doing? What do they respond to? What’s their job?

The science continues!

And in the meantime, while you wait, have a HobNob shake. It’s based on the recipe for the Max Brenner cookie shake, lord among shakes that it is. It looks good, it tastes good, it smells good and… well I guess it has a good texture, in the scheme of things. Your orbitofrontal cortex is going to assign awesomeness to this via the striatum so hard.

Read on for the recipe for a HobNob shake.

Hustlin’ like a huswife

Real, no-foolin’ butterbeer. That’s what this is. Based on a Tudor recipe dating back to 1594 in a book called The good Huswifes Handmaide for the Kitchin. What are ye waiting for? Get to the kitchin!

I’m rather loving the Handmaide at the moment. Next up — Tudor custard. Then maybe Tudor orange and apple tart. Then… probably not the “Conie with a Pudding in his bellie”. Boiled, no less (sorry, boyled).

Looking through the Handmaide you get an idea of what things were popular and trendy at the time (well, in wealthy households, presumably — if my mum thought oranges were an awesome and exotic gift to receive at Christmas in the 1950s in the UK, I can only imagine how precious they were in the 1590s). On the spice front, the Tudors seem to have been pretty big on mace so I decided to hunt some down and I’ve put that in the butterbeer, for olde tyme’s sake.

However, if you’re precious about your beer at all, this might not be the recipe for you. But if hot, spiced, almost custardy beer sounds bang up your alley (it’s like the mulled wine of… beers…) then this could be a life-changing moment for you and you should brace yourself accordingly.

As for a research journal article to discuss on the topic, what can I say? This letter to the editor was published in the Journal of the American Academy of Child & Adolescent Psychiatry, right after a letter about citalopram and dystonia:

Welsh, C.J. (2004). Harry Potter and butterbeer. J Am Acad Child Adolesc Psychiatry, 43(1), 9-10.

Basically, the author just machine-guns some Harry Potter stats around (55 languages! 170 million copies! etc.), then goes into enough detail about the themes of the books that it makes me suspect that this 46-year-old psychiatrist might be a rabid Harry Potter fan (or someone close to him is a rabid Harry Potter fan, although I prefer the other theory). Then he raises the question, given the sensitive treatment of many real-world themes in the books, why does J.K. Rowling think it’s ok to encourage children to drink beer — or at least to imply that butterbeer is maybe possibly alcoholic and then depict 13-year-olds enjoying it?

Oh I don’t know, maybe because it’s magic beer?

Actually I really don’t know. He does say at one point that the beer is noted in the book to have a warming effect, which is, as he says, “a quality typically used to describe alcoholic beverages”. Well, maybe butterbeer is warm thermally? Tudor butterbeer certainly is. You heat it up in a saucepan. What do you make of that, huh?

He then says that a house-elf called Winky gets drunk on butterbeer, testament to its alcoholic properties. Well, you know, chocolate can kill my dogs and yet make me simply rather contented — maybe butterbeer only intoxicates elves? (cf. The Lord of the Rings where it doesn’t.) Maybe it’s impossible to know because I can’t go and find a house-elf and do a behavioural study on the effects of fictional vs non-fictional alcohol.

He then cosies up to Rowling again, saying how fantabulously obliteratingly wonderful her stories are, but! Can we use butterbeer in Harry Potter as a way of teaching children to not consume alcohol until they reach an appropriate age? Can we use Winky as an example of the misfortune that befalls those who abuse alcohol?

Sure why not. But somehow I think kids are probably more likely to get bad messages about alcohol consumption from the behaviour of their immediate family members rather than bloody Harry Potter (e.g. see Cranford et al. and plenty of other papers). But then again, I’ve heard tales of children who cried when they didn’t get their letter from Hogwarts, so we perhaps shouldn’t underestimate its power — although surely there are more interesting things in Harry Potter for children to try to copy other than drunk dirty house-elf behaviour… aren’t there? Well?

In conclusion, mentioning a massively popular franchise will get you published in a slightly fancy journal. (JAACAP has an impact factor of 4.983.)

BRB, writing a paper to submit to Nature that mentions something about Twilight. (Made slightly more difficult by the fact that I’ve never read the books or seen the movies, but I’m sure I can figure out all I need to know from the movie posters.)

Read on for the recipe for butterbeer.

Of beer and butterbeer

So, you’re a research participant and you’ve signed up for a “verbal styles” experiment in your local university psychology department. Good on you! Those guys always need participants, so thank you for being so generous with your time. In this experiment, you’re given a list of words and you just have to read each word, think of a synonym, then write the synonym down. Pretty simple.

Ok you’re done. Awesome. How easy was that? We’ll be able to analyse your verbal styles now. And now that you’re finished, just wait around for half an hour or so because we’ll need to take some follow-up measurements in a bit.

Actually — oh. Oh no. There’s been a cancellation in another study and a participant in that one has dropped out and we need a replacement. It’s just a taste-testing experiment about beer. It’ll only take 10 minutes. Can you do it? Yes? Brilliant!

So you’re taken to another room where that experiment is being conducted. There are three different beers* — A, B and C — in non-descript disposable cups and you just need to drink some of each and rate them using a questionnaire about how sweet or dry they are, how carbonated they are, etc.

Ok now you’ve done that, we’ll go back to the other room for the follow-up measurements for the other experiment. Cool.

Well, then. Have you guessed what’s happened? Did you have an inkling that all of that, from the word lists to the beer tasting, was part of one big experiment? Maybe you did, but the participants who went through that exact scenario in a study by Zack and colleagues sure didn’t.

The important thing here is that during the word list part of the experiment, different participants were given different kinds of words to come up with synonyms for. Some people had lists with words related to negative mood and emotion, some were given lists with words related to positive mood and emotion, and some people had lists with just neutral words.

And the interesting thing was this: participants exposed to lists of negative words (e.g. anxious, sad) during the list experiment consumed significantly more beer during the tasting than those who were exposed to lists of positive words (e.g. happy) or neutral words (e.g. frequent). Simply priming people with negative words is enough to make them drink more.

(Oh god, don’t look up “sad” in a thesaurus!)

It seems that maybe negative words and their associated moods are tied in closely enough with the consumption of alcohol that just being exposed to the words primes drinking behaviour — mentioning these negative words incidentally activates the brain’s representation of alcohol consumption, although not at a conscious level. And this is in young university students, not in problem drinkers who regularly use alcohol to cope with negative situations (although everyone in the experiment did complete a questionnaire about drinking behaviour and some participants were classified as having some problem drinking symptoms).

This association between negative mood and drinking is interesting because you would kind of think that, for a lot of people at least, drinking is associated with positive times (celebrations, parties, etc.) so exposing people to positive words would prime their drinking behaviour because positive mood and drinking are associated. But it didn’t — maybe because positive mood is associated with the context of celebrations and parties generally (e.g. having a lot of people around and socialising), so alcohol doesn’t factor in directly in that case. Yet somehow, perhaps through cultural constructs and influences, the brain seems to unconsciously think that being in a negative mood calls for alcohol! So…

Cheerful! Joy! Puppies! Happy fun ball!

Now that you’ve read those words and don’t feel like drinking… make some butterbeer curd to go with salty, buttery, delicious madeleines. I came up with butterbeer curd just the other day, given that I’ve already made proper butterbeer before, based originally on a charming Tudor recipe from 1594. My next post will be about the actual butterbeer recipe itself! Ooooh, ooooooh, the intrigue.

Recipe for butterbeer curd and salted madeleines after the cut.