[branes] Emotions, health, & stress
Jan. 6th, 2006 10:55 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
julietI 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...
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...
