[branes] Emotions, health, & stress

[juliet]

I have been intending to post stuff about BRANES (in the psychological sense) all term, and, er, hardly done it at all. Whoops.

So, yesterday I was reading about emotions...


Stress and health
It is a commonplace comment that stress makes you more likely to get ill. In fact, this seems to be true only of long-term stress (over a month) - less than that doesn't give much of a difference in studies (studies often carried out on medical students around their finals). The reason for this is that stress raises cortisol levels. Cortisol acts to increase blood sugar levels and speed up the metabolism (broadly, to enable the fight/flight reaction). However, this means that resources are diverted away from other areas - such as protein generation, and the immune system requires protein to function properly. Hence: lowered immune system, more likely to get ill.

There was also some interesting stuff about the way in which the immune system generates 'feeling ill' (loss of appetite, feelings of weakness, sleepiness). This is done via signals up to the brain, rather than being a direct function of the immune activity. The benefits of feeling tired and weak are fairly clear - it encourages you to sit around quietly, and not use up valuable resources that can be directed to the immune system. It might seem that a loss of appetite would be counterproductive - it's possible that this reaction is because for most animals, finding food is hard work (unlike modern western humans...) so lowering the appetite reduces the chances of using up resources looking for food.

Lastly on stress and health - ulcers are associated with stress, but in fact it's not the stress reaction that causes them, but the reaction to the stress reaction. Stress increases your sympathetic nervous system activity (increased heart rate, for example), but decreases your parasympathetic nervous system activity (responsible for digestion & other similar 'slow' processes). When the stressor goes away, the PNS fires up stronger in reaction - so digestive activity increases, making damage to the stomach lining more likely (particularly if you have an empty stomach).



Mental and physical aspects of emotion
There's some disagreement amongst psychologists as to the relation between the mental experience of emotion (feeling fearful, happy, amused, scared, etc) and the physical reaction/experience. Some claim that the physical experience generates the emotional one; others that both are caused by the stimulus prompting the emotion. The importance of the physical side can be demonstrated by the fact that if you get people to hold a pencil between their teeth (thus producing a 'smile'), they will rate cartoons as funnier than people asked to hold a pencil between their lips (thus producing a 'frown'). So all this stuff about how smiling when you feel down will lift your mood has some evidential basis. My textbook also quoted a case of a girl who was having brain surgery - in these circs they often keep the patient conscious, so they can prod at the brain & find out what the reaction is, to make sure they have the right bit of brain. Anyway, so they prodded one bit, and she smiled; prodded a bit harder and she laughed. They did this a few times, and every time when asked why she had laughed, she gave a different reason / different thing that had amused her. My textbook claimed this as an example of a physical reaction (laughter) making the mind/brain generate an emotional response (amusement). However, it seems to me that it could just as well be argued that the brain stimulation generated an emotion (amusement), which was expressed by laughter; and the post-hoc rationalisation is just the brain doing what it does best - trying to generate a coherent world experience.



Serotonin & behaviour
There's a fair amount of evidence that serotonin has an effect on aggression - mice with low serotonin turnover (i.e. a low rate at which serotonin gets taken up & regenerated - this is a more useful measure than just serotonin levels) are more likely to be aggressive to intruder mice, and there's evidence of a similar link between violent behaviour and low serotonin turnover in humans. Anyone who's ever been to a dance club will be familiar with the happy fluffy effects of massive serotonin release... However, it seems that it's actually broader than this - that low serotonin turnover is associated with higher impulsiveness, and lower ability to control unwanted behaviour generally. I wonder whether the happiness-inducing effects of serotonin are independent from the violence-reducing ones, or linked - i.e. is it because one is better able to control violence/unwanted behaviour that one is happier; or that being happier leads one to be better able to control unwanted behaviour; or that the two things simply occur at the same time. The middle seems the most intuitively plausible, but that may again be a post-hoc rationalisation, if one tends to experience the two effects together.


I need a BRANES icon. I shall use a rat for the moment, because rats seem to be pretty central to experimental psychology...

Comments

[katstevens.livejournal.com]

How about this?



I am going to have some lemmun et ginger tea now.

[easterbunny.livejournal.com]

Branes: choice of this or this?

[ewx.livejournal.com]

Now I really want someone to prod my brain to make me laugh so I can see what rationalization I come up with.

[marnameow.livejournal.com]

There are interesting relationships between the physical and emitional aspects of panic - I spent a goodly bit of time working through those last year. I would have to think (from looking closely at it in mine own head) that it definitely begins in the brane, and that triggers the physical stuff (as in, just thinking about certain things would make me have the physical reaction, but the thinking would be the first thing). And then the physical reaction feeds back into the emotional bit (like, my legs have tensed up so there *must* be a reason to be scared) and it gets very circular. So *there* it's working both ways, but I'm sure is triggered by the brane, initially.

Of course, that's malfunctioning brane and not normal functioning brane.

Branes are interesting!

[rgl.livejournal.com]

I thought ulcers were caused by Helicobacter pylori, for which the researchers won a Nobel prize last year? Could be wrong though - I don't know anything about the GI system.

Re the serotonin stuff... One reads lots of attempts to explain behaviour in terms of whole-brain levels of neurotransmitters, and for two main reason - you can change neurotransmitter levels with drugs, which is something there is a lot of money and interest in doing, and it's relatively easy to explain. The other way to explain behaviour is in terms of neural network type models, but there's not quite so much money in that and far fewer people can understand the research (I tried and failed). The two extremes are appropriate in different areas, I guess - IMHO it would be silly to try and explain behaviour in terms of whole-brain glutamate levels, for example, as glutaminergic neurons are everywhere, while conversely there are two pretty clear dopaminergic pathways in the brain so it's more plausible that they might have specific functions. But I've never been sure what the evidence is - and this is probably just my ignorance as I did very little pharmacology - that there is a functional serotonergic system rather than just lots of different unconnected effects happening at once.

[juliet]

Only around 80% of those who get ulcers have Hp kicking around, & lots of people who don't get ulcers also have it. So there's something more than just Hp going on there.

I'm obviously doing all of this on a fairly basic level, but I've not seen much evidence of a full system either. I mean, there's evidence that serotonin does various things (personal experimental data [ahem] certainly indicates that releasing lots at once does happy friendly things to the brain, and the consequent dip in serotonin does weepy miserable things unless one takes steps to replenish levels (hurrah for 5HTP); and SSRIs clearly have an effect). But yes, what I've read is just people saying that serotonin does X and Y (or that low/high serotonin turnover levels are linked to X and Y). Above is just my own speculation about links.

My gut instinct is, probably unsurprisingly, that neurotransmitters and neural network models both have important things to say about how behaviour works. Possibly in the same sort of way that Marna discusses panic-stuff above: reinforcement actions.

[rgl.livejournal.com]

Yes... Incidentally, I wasn't meaning to sound like I was getting at you, if I did. There are some prevailing attitudes in the way the whole of neuroscience is taught and researched that irk me, and the concentration on neurotransmitters rather than neuronal connections is one. This is just my own academic prejudice though. I have a selection of long rants about how awful contemporary neuroscience is, with which I occasionally bore people...

[juliet]

No, not at all. I agree with you on the neurotransmitter prejudice; it seems clear that neurotransmitters do a great many things, & in particular, drugs that affect them seem like a really big case of sledgehammer/nut error. (although otoh there's not much else available atm, so people have limited choice :-/ ).

One of the things that has pissed me off all term is what seems to me to be an enormously ignorant attitude to animal experimentation. e.g. when talking about sexual orientation, my lecturer said that increased testosterone led to female rats mounting other rats "which they don't normally do". Not So. I can promise that female rats *regularly* mount other rats; in part it seems to be a dominance behaviour, but it's also clearly linked to their heat cycle (it's quite easy to identify when a female rat's on heat - they're jumpy, & arch their back & wiggle their ears when you scratch them behind the ribs, i.e. where a male rat would grab them). I do not know to what extent this behaviour also happens with mixed groups of rats (we've only ever had females, & single-sex grouping may affect behaviour), but nevertheless: gross oversimplification of the situation. There've been quite a lot of similar instances, which leaves me with a certain level of scepticism about the results of such experiments. Mind you, I do not of course know whether this is lecturer error or experimenter error.

So, er, yes, I have issues with the way I'm being taught, as well, & that's only at a very basic level of information! (the course is called "The Biological Basis of Behaviour" & is for 2nd-yr BA psychology students, or, as in my case, 1st-yr grad diploma. So not v advanced).

[rgl.livejournal.com]

Yes, I think you can tell how comparatively "young" neuroscience is, as a science, by how quickly you reach the point where you're at the edge of our current understanding, and the stuff you're being taught is actually quite shakily understood.

There's a joke my dad tells about science, which applies quite well to neuroscience IMHO. It's a dark night and a man is walking home down the street when he sees someone else scrabbling around under a streetlight. "Are you OK?", he says. "Yes", says the other bloke, "but I've lost one of my contact lenses." "Well, where were you, roughly, when you lost it?" "Over there", says the man on the ground, pointing about 20m back down the dark road. "Well why are you looking here, then?" asks the would-be Samaritan. "Because there's more light over here."

There are lots of pretty unsubtle neuroscientific techniques that provide some sort of "light", but I'm not sure that they're going to answer the questions that people originally set out to answer.

And that concludes my Thought For The Day... :)

[sbp.livejournal.com]

I've been to dance clubs lots of times and experienced no fluffy releases.

[dogrando.livejournal.com]

I think she's referring to the come-down. ("Come" "down"... geddit?)

[jvvw.livejournal.com]

That's all interesting. Out of curiosity, do psychologists differentiate between different types of stress at all? (I don't know how they define stress in fact, so maybe some things that I'd describe as stress aren't in fact).

[juliet]

Not sure! I think it depends on what exactly you're looking at... Certainly it's accepted that stress is not necessarily a 'bad' thing & can be useful in some circumstances.

The standard definition of stress is 'the nonspecific response of the body to any demand made on it' which is really pretty broad. I think the main distinction is between pleasant & unpleasant stressors.

[mrs-leroy-brown.livejournal.com]

printing this to read at lunchtime...

[juliet]

No, I don't know you, & I find your comments peculiar (reread the post; I was discussing my course reading, not any hypothetical 'bad times' I might be having) and inappropriate (e.g. calling me 'babes'). Please go away.