Action potential

“Science has achieved some wonderful things of course, but I’d far rather be happy than right any day.”
“And are you?”
“No. That’s where it all falls down of course.”
– Douglas Adams, The Hitch Hikers Guide to the Galaxy

My first degree – a BA – was in philosophy. I say was, because after four years and much grief I ended up leaving without graduating. I got a DipHE (no, I’d never heard of them either).

Shortly afterwards I enrolled with the OU and started studying both Human Biology and Ancient Greek. Which is what happens when you have undiagnosed bipolar disorder and a university prospectus.

I never finished that, either, although I can at least transliterate Greek script and get annoyed when people use the wrong sigma.

I did graduate, eventually. I got a BSc in psychology from Birkbeck, which is a college specialising in part-time degrees. It took five years (including a year off while I had a depressive breakdown), a lot of bloody mindedness, and a number of all-nighters after which I had to put in a full day at the office. Doing a degree part time while working full time is… well, 200 people started the course, 80 finished it.

Most of my peers graduated in 2002. I managed it, finally, in 2010.

I’m smart, and I always have been. I’m just not very good at it.

I used to be.

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188

After my psychology lectures, I used to catch the 188 home. I was living in Waterloo – one of the happiest flats I’ve ever lived in.

Coffee with a friend this evening in Holborn; Pret, then My Old Dutch (amazing, massive pancakes – seriously, give it a go). Catch the 188, like stepping back into an old routine. Bright, black London and drizzle.

All those years ago, I bought by copy of Gazanniga at the Waterstone’s on Gower Street (a beautiful bliss of a bookshop – seriously, give it a go). Brief panic when I got home and thought I’d left it on the bus, joy when I found it at the back of my bag. It must have been the second year – when we got our first real biopsychology lectures, and I was desperate to get started. I’d decided the previous year that I had a definite love for neuroscience and I lapped up the lectures and chapters on visual processing, rolling the brilliant new names around my mind – lateral geniculate nucleus; optic chiasma; koinocellular.

I loved brains, knew I wanted to know more, understand more. Remember riding home on the 188, head full of brains – brains that glowed with discrete functional blobs, brains that were really just a wrinkly surface with sketched in functional areas, a hastily drawn map of an unseen archipelago. And riding tonight, on the 188, thinking how crude my concepts were. Riding tonight, on the 188, head full of brains – brains overtopped with interleaved layers, wired throughout to knots of nuclei that speak among themselves and within themselves and out, with neurons like jelly forests, each one a tickertape cacophony of computation. Don’t even get me started on astroglia.

And thinking, brilliantly, wonderfully – how crude my concepts must still be.

Ring the alarm!

My twitter feed has been somewhat abuzz today with this story about the ‘discovery’ of the chemical responsible for depression and anxiety, dubbed the ‘misery molecule’ by various sections of the press and reported on in a confused and hard-to-follow manner, with the main take home message being ‘more drugs (maybe)’.

First things first – I know this may come as a shock to many of you, but the reporting of this in the media is overblown and misguided. The headline from the Independent serves as a good guide to the misunderstandings present in the reporting of this story:

Scientists discover the molecule responsible for causing feelings of depression 

From this you might surmise that a new molecule has been discovered, and that it is responsible for causing feelings of depression; the implication of the rest of the article is that this molecule has a role to play in pathological depression. Lest you think I’m being too harsh (journalists aren’t responsible for headlines, after all), the body of the article contains the sentence

…scientists have now discovered that the protein receptor CRF1 is responsible for releasing hormones which can cause anxiety and depression over extended periods of time

Similar stories have cropped up in the Times, the Daily Mail, and various other news sources (notably, the reporting in the Financial Times was much better).

Unfortunately for these stories, this is not a previously unknown molecule, and it’s role in either feelings of depression or depressive disorder is  complicated and uncertain.

Human experience, complex emotions and mental health not reducible to a single molecule – surprise!

What has been discovered is the structure of the molecule – this gives us a better chance at figuring out how it works and makes designing drugs which work on it easier. The molecule in question is called CRF1, and it’s a receptor – it sits on the surface of cells and transmits information from outside the cell to inside it. Even on a very reductionist understanding, it is not responsible for feelings of depression, any more than your tongue is responsible for the taste of sugar.

CRF1 is part of a pathway called the Hypothalamic Pituitary Adrenal (HPA) axis. The interaction of all the bits and pieces of this pathway are involved in the ‘stress’ response; it’s a good example of how the brain and rest of the body work together, and it’s a pathway which is often found to be disrupted not only in people with depression, but also in those with psychosis. It involves – as you might expect – the hypothalamus, the pituitary, and the adrenal glands.

The hypothalamus is a small structure which sits deep in your brain and is a kind of ‘master switch’ for all the body’s hormones – long-distance messengers which diffuse signals throughout the body. One of the hormones controlled by the hypothalamus is cortisol, although this being biology nothing is simple; cortisol is not released by the hypothalamus, or even by the brain, but by the adrenal glands which sit atop the kidneys. The hypothalamus itself, while it acts as a master switch, gets it’s neighbour – the pituitary – to do most of the heavy lifting.

Various other parts of the brain, notably the amygdala and the hippocampus, send signals to the hypothalamus which provide information about any potential threats. If it gets such a signal, the hypothalamus releases a chemical messenger known as Corticotrophin Releasing Factor (CRF), which tells the pituitary to release a further messenger, Adrenocorticotropin Releasing Hormone (ACTH), into the bloodstream. ACTH acts on receptors on the adrenal cortices – remember these are the glands which sit on top of the kidneys, and which release cortisol in response to ACTH. Cortisol goes on to have many, many effects on various tissues throughout the body, effects which are mediated through a couple of receptors called the Glucocorticoid Receptor (GR) and the Mineraloreceptor (MR).

You might think this is a roundabout way of doing things (and you’d be right), but each additional step allows for modulation and modification of the signal – in biology, more steps make for a better dance.

So – what’s this all got to do with depression? Well, being constantly stressed all the time isn’t nice, and nor is it good for the brain – cortisol is great for adding a boost to the engine, but you’d soon wear the machine out if the boost was constantly applied. To prevent this from happening, neurons in both the hypothalamus and the pituitary express glucocorticoid receptors; when cortisol acts on these receptors, the activity of the HPA axis is inhibited. This ensures the cortisol alarm is short lived – so long as the receptors on the hypothalamus and pituitary are doing their job.

As you might have guessed, in at least some types of depression this feedback loop fails. There are good reasons for thinking that when this system malfunctions, it’s the glucocorticoid receptors which are the weak link in the chain, and this leads to abnormally long ‘recovery times’ after stress exposure. It’s as if, when it comes to the racket made by the cortisol alarm, your brain is a little bit deaf. The alarm keeps on going on, and on, and on.

Worse, the cortisol alarm actually seems to damage cells in the hippocampus, leading to lower hippocampal volume in some depressed patients. The hippocampus is best known for its role in memory formation but, as I say, it also sends input to the hypothalamus. The nature of this input is inhibitory – that is, it helps turn down the alarm (the amygdala, meanwhile, helps turn it up – which makes sense when you think about the amygdala’s role in fear and anxiety). Of course, if pathologically raised levels of cortisol are damaging the hippocampus, that could well damage its ability to turn down the alarm. As the amygdala doesn’t appear to experience any such damage, you end up with a circuit which is easy to turn on and easily turned up, but resists being turned down or off. Can you imagine a car alarm like that?!

(As an aside, memory problems are a known symptom of major depressive disorder, and it’s extraordinarily tempting to link the lower hippocampal volume seen in depressed individuals with these memory problems; it’s certainly not going to help, but just as there’s more to mood than molecules, there’s more to memory than the hippocampus; depressed individuals also have problems with attention and concentration, both of which could conceivably lead to problems with memory via a different route).

What are the wider effects of this raised alarm? That is a trickier question to answer; the safest response is that there is an association between disrupted cortisol regulation and some (but not all) forms of depression. Current antidepressants do not act directly on the HPA axis, although successful treatment with them seems to have beneficial effects on both the cortisol response and hippocampal volume (we really don’t know much about their mechanisms of action at all, either on the HPA axis or on the brain more generally – a post for another time, perhaps).  Wouldn’t it be great if we could design some drugs which could turn off this runaway alarm directly, and so maybe resolve depression?

And here, at last, we get to the point of this paper. The receptor CRF1 is found on cells of the pituitary gland; they respond to the first ‘go’ signal from the hypothalamus, the chemical messenger CRF (CRF binds to CRF1, see?). Knowing the structure of this receptor makes it a lot easier to design drugs that can inhibit it’s function, working to turn down the alarm. The reasoning goes lower HPA axis activity, a miracle happens, then no depression.

As you can see, it’s a theory that needs a bit of work. But hey – you never know until you try.

Mirtazapine, intense as in

Peaches! It's a visual metaphor, maybe.So last week I asked for my prescription to be changed.

I’ve been on citalopram for about a year now – it’s is a common-or-garden antidepressant which has a very similar cellular action to Prozac – they’re both what you may or may not know as ‘selective serotonin reuptake inhibitors’ (SSRIs). I won’t go into the nuances of SSRI treatment here, save to say they work to an extent, and for some people more than others. I’m fortunate – citalopram seems to work very, very well with me. So why change?

Side effects.

The side effects of SSRIs are usually not too bad – the worst I’ve ever had, or seen anyone have, is an immense tiredness, which can be enough to lead people to quit. But the tiredness I experience on citalopram isn’t anything troubling to me; I need an afternoon nap and that’s pretty much it. Given how profound and dangerous the depths of my depression can be, a few piddling side effects really aren’t worth worrying over, not in the heat of the moment (or, rather, the depths of the dark).

After a while tho, when all is sunny and well, what had been niggling side effects take on a change in character; specifically, the rock-bottom libido I’ve lived with for a few years now, notwithstanding alcohol inebriation. SSRIs are known to sometimes muck about with sex drive, and after mirtazapine was brought to my attention I thought it worth a punt.

Even so, I don’t have great hopes for this ‘working’; that is, delivering some miraculous return of my sex drive. Libido is complicated and impacted by a whole range of factors, from depression itself to past sexual and romantic history, confidence, self-perception, all the way up to culture and subculture, and perception of one’s own role within that wider context. Even if my predicament was initially brought on by a simple chemically-induced neurobiological change, it will be far from simple now. Brains are complex, and people even more so. Still, this is low hanging fruit (fnar), and you have to make a start somewhere – this is a start, of a kind.

And what a kind! My GP looked surprised at my request, pointing out that mirtazapine is usually prescribed for more anxious-depressive types, those filled with a worrying energy. The drug, he explained, can have quite profound sedative effects. Take at night. You might have difficulty waking. Dreams may come.

Dreams did come, and they’re still coming, though I’m told they’ll eventually, probably, fade. Some claustrophobic, some vertiginous, some icy and frightening, all suffocating, intense. Intense as in seeming profound, only to tatter away with a moments thought. Intense as in teenage crush, primal and primary, confusing. Intense as in shrooms, hilarious because, hilarious because hilarious, because. Haunting, and like ocean waves dragging you down as you wake, as you surface, only thrashing and gasping and drowning again into dreaming, and again, and again into dreaming.

The first day, my eyes opened and I got up, I drank strong coffee and more strong coffee but never really awoke, napped for hours before exhausted went to bed, another twelve hours, awoke to dreaming, awoke to dreaming, awoke.

The second day – strange and a world full of echoes and space, but more awake. I think I’m lucky – the tiredness fading fast and swift now, even if the dreams still boil away at night; while waking is still a confused surfacing it’s getting easier. During the day I can write, read, I can even talk and think, and it’s been less than a week. That’s some quick neuroadaptation!

Maybe I’ll even get my libido back.testosterone

Hiding behind the sofa

Sack person from Little Big PlanetMy little niece has just started playing Little Big Planet on the PS3, I’m told she runs for cover when any lava comes on screen. It’s cute.

And it’s strange, isn’t it?

Maybe you don’t think it’s strange, maybe you’re so used to kids hiding behind the sofa that you think it the most pedestrian thing in the world.

I think it’s strange.

And then I think of watching a film though fingers, or turning away during the gruesome bits; it hits me, and I think ‘that’s strange, too’.

Because there is nothing to be frightened of. And we know there is nothing to be frightened of. We experience, again and again, complete safety when we watch these things, when we play these games. We look at toddlers and smile that they’re so scared of the in-game hot lava that they’ll drop the controller and run for safety. At kids who run from the monsters in Doctor Who, as if – we tell ourselves – as if they think the monsters might come out of the TV and get them for real.

As if!

But we know better, we know where the real monsters lie in wait, and we know they’re not in the TV. But still we watch, sometimes, through fingers.

Isn’t it strange?

Why do we do it? Why do they do it? You’ve got to be so careful interpreting what children say – or maybe just as careful as you are with adults, but in a different way; do children understand what you’re asking when you ask if they’re scared of the lava on the screen? Do they understand what they’re saying, when they say ‘yes’? Because of course they are, otherwise they wouldn’t hide! (What peculiar questions these grown ups ask!).

Do you get more specific, and ask them if they’re scared of the lava coming out of the TV and hurting them?

(When I was a kid, I used to be frightened of being upstairs in our house on my own. One of my elder brothers once asked, mockingly, ‘What are you so afraid of? That your toys will come to life and come to get you?!’.

And I thought, ‘well I am now!’).Phrenology head and almonds

Inside your brain you’ve got two ovoid structures called the amygdalae; they’ve got close connection with your two hippocampi, structures which we know are vital for ‘memory’, as we commonly understand the word. The amygdala seems to get especially excited when we’re in danger, or if we perceive a threat. Its close connections with the hippocampus act as a kind of ‘notice this!’ signal, ensuring you remember situations when bad things happened and thus allowing you to avoid them in future.

Undergrad textbooks sometimes take this and conclude that you need the amygdala for fear processing; that the visceral, panic sensation of fear somehow is part of the amygdala’s functioning. Myself, I keep thinking also of the remark in ‘Into the Silent Land‘ that the amygdala is possibly more involved in contextualising fear; thinking of the woman who, deprived of its processing, would stand passive and smiling through a mugging but could also be pinned to the armchair in fear’s grip while watching TV.

(As an aside, the word ‘amygdala’ comes from ancient greek and means ‘almond’, and the amygdala looks like an almond; ‘hippocampus’ comes from the ancient greek ‘hippokampos’, which means sea-horse, and the hippocampus looks nothing like a sea-horse, not even like the crazy-ass sea-horses the Greeks imagined. So long as you remember that anatomical terms either do make sense or do not make sense, you’ll have no problem remembering them)

Often we talk about ‘higher’ and ‘lower’ brain functions; the amygdalae sit at the lower end, apparently driving primal emotional responses which are then modified, modulated and given texture and nuance by the ‘higher’ centres, up and out in the wrinkly cortex. It’s tempting to say that as children we have less control over these ‘lower’ centres – certainly the circuitry of the prefrontal cortex is underdeveloped compared to an adults, and these areas do send many projections deep into the lower processing centres. It’s nice and neat to say that without enough control, or with too much stimulation, or both, our rational selves are displaced, leaving us frightened even when we know we’ve nothing to be scared of.

I’m lured by this explanation, but I’m wary; I’m wary of the Cartesian confusion we can slip into when talking about competing drives and desires inside a single soul; I’m wary of this ‘higher v lower’ dichotomy, which carries so much historical, moralistic baggage. Plato and Freud both thought we had three parts to our selves, which to me seems at least two too many. Besides, as any of my ex’s will attest, I am not good with nice and neat. I don’t trust it; I’ve been let down too many times in the past. Brains are complicated and people even, even more so. Our desires and knowledge and behaviours bleed into one another, from it all we emerge, often unsure of ourselves and our reasons why. We find ourselves on a diet, scooping ice cream into our mouths; promising never to drink again, again; find ourselves watching, frightened and delighted, through tight fingers.

Strange, isn’t it?