Why do nerves make us forget?

We all know the symptoms of nerves – cold sweaty palms, shallow fast breathing, uncontrollably shaky limbs, the frequent and urgent need to go to the toilet, and a heart that’s beating double time while attempting to escape through the wall of your chest. Although people vary in their ability to control their nerves, most people suffer from some kind of performance anxiety when playing music in front of an audience.

One of the biggest contributors to performance nerves when playing from memory is the fear of forgetting. And not without good reason since, somewhat ironically, one of the biggest disasters that can befall a nervous musician is that they do indeed forget the music. Without warning, a piece you’ve played for years, know inside-out and can play perfectly at home, suddenly disappears from your memory without a trace. Boom! Why does this happen?

When stress occurs, the body reacts by secreting stress hormones from the adrenal glands situated above the kidneys into the blood stream. Adrenalin is usually cast as the villan, due to its role in the so-called fight-or-flight response: it increases your heart rate, breathing and blood pressure to make sure you’ve got plenty of oxygen supplying your muscles; it shuts off blood supply to your limbs so they don’t bleed too much if they are wounded and to prioritise large muscles; it makes you want to empty your stomach and bowels so you’re not wasting energy on digestion and are ready to run; and it causes electrical impulses to be sent to your muscles causing contractions to get them ready for action. All of which is very useful if you actually needed to fight or fly, but not so helpful when you want to stay put and give a moving musical performance!

There are actually two main classes of hormones released as a result of stress: catecholamines (including adrenaline) and glucocorticoids (the most important of which is cortisol). Although they may be secreted together, these classes are made from totally different starting materials (tyrosine or cholesterol respectively), come from different parts of the adrenal gland, and have different functions. One of the main roles of  cortisol is to increase blood sugar levels to keep your muscles well fuelled. Levels of cortisol usually follow a natural 24-hour circadian rhythm: elevated in the morning (making us more alert) and declining during the day and into the evening.

Adrenalin&Cortisol

There have been lots of studies on the effect of stress on cognition and memory, reviewed by Lupien and colleagues [1], which mostly cast cortisol in the starring role. Unlike adrenalin, because of its fatty nature cortisol can easily cross the blood–brain barrier and bind specific receptors in regions of the brain involved in learning and memory – the hippocampus, amygdala and frontal lobes. Once there, the hormone affects levels of neurotransmitters released and taken up by specific synapses in the brain [2].  The effect of cortisol on memory is dose-dependent – it has positive effects at low-medium levels but negative effects at high levels. (Note that although adrenaline cannot readily access the brain, it can still have an impact on memory via its actions on the nervous system, and through a vicious feedback loop where being nervous makes you more nervous about being nervous!)

One of the first studies to focus on the effect of acute stress on memory retrieval in humans was undertaken by Kirschbaum and colleagues in 1996, who investigated the effect on word-list and spacial memory [3]. The first thing they did was measure the effect of giving people an oral dose of cortisol (or placebo) on memory. Individuals who received cortisol treatment showed impaired performance in declarative memory tasks – like recalling a list of words – but not procedural memory for skills . This result was confirmed by a later study, in which performance in a word-recall test for a list of words learnt the previous day was significantly reduced as a result of cortisol treatment [4]. Although there was little effect on immediate recall or word recognition, there is some additional evidence that cortisol reduces working memory capacity [5].

Kirschbaum and colleagues also investigated the effect of natural acute stress on memory, by asking participants to perform a public speaking task and mental arithmetic in front of an audience before doing their word-recall test [3]. This had the effect of raising levels of natural cortisol and also significantly impaired memory performance. Again, this finding has been reproduced in a more recent study, which showed not only that long-term memory retrieval is significantly impaired after an acute psychosocial stressor, but also that emotionally arousing words are more affected than neutral words [6].

So it seems that although adrenalin causes most of the physical symptoms associated with performance nerves, its friend cortisol is actually responsible for most of the cognitive problems. High levels of cortisol significantly impairs retrieval of emotionally-laden information from explicit long term memory, but luckily procedural memory is relatively unaffected. This makes a lot of sense from an evolutionary perspective, particularly for self-defence – don’t think, act! It also fits well with the experience described by several musicians in their interviews of acute memory lapses in performance being caused by trying to actively remember details. Although we can’t stop* the effects of these powerful hormones, knowing that procedural memory is unaffected by performance nerves could be hugely useful in preventing memory lapses during performance. Perhaps nervous performers should trust their preparation and go with the flow.

AddendumSome performers turn to drugs to help with the pressure of performance nerves. In particular, beta-blockers are widely though controversially used to reduce performance anxiety. They work by preventing adrenalin from binding its main receptor, which stops it having any effect. As you can see from the chemical structures (sorry, I couldn’t resist!) adrenalin and cortisol are very different in shape, and they bind completely different receptors in the body. This means that beta-blockers do not block cortisol receptors, and therefore have no direct impact on the effects of cortisol. So even if beta-blockers help control your adrenalin-pumped body, they don’t have much to offer your cortisol-drenched mind…

References:

[1] Lupien, S.J., et al., The effects of stress and stress hormones on human cognition: Implications for the field of brain and cognition, Brain and Cognition 65 (2007); 209–237

[2] Sandi, C., Glucocorticoids act on glutamatergic pathways to affect memory processes, Trends in Neurosciences 34 (2011); 165-76

[3] Kirschbaum, C., et al., Stress- and treatment-induced elevations of cortisol levels associated with impaired declarative memory in healthy adults, Life Sciences 58 (1996); 1475-83

[4] de Quervain, D. J.-F., et al. Acute cortisone administration impairs retrieval of long-term declarative memory in humans, Nature Neuroscience 3 (2000); 313-4

[5] Lupien, S.J., et al., Working Memory Is More Sensitive Than Declarative Memory to the Acute Effects of Corticosteroids: A Dose-Response Study in Humans, Behavioral Neuroscience 113 (1999); 420-30

[6] Kuhlmann, S., et al. Impaired Memory Retrieval after Psychosocial Stress in Healthy Young Men, The Journal of Neuroscience 25 (2005) 2977–82

 

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About Caroline Wright

pianist, composer, scientist
This entry was posted in Reviews and tagged , , . Bookmark the permalink.

3 Responses to Why do nerves make us forget?

  1. {vapor pen says:

    I was wondering if you ever considered changing the structure of your blog?
    Its very well written; I love what youve got to say.

    But maybe you could a little more in the way of content so people could connect
    with it better. Youve got an awful lot of text for only having one or two
    images. Maybe you could space it out better?

    • Thanks for the comment – I guess I’m not too worried! My aim is really to collect information, though I should probably try harder to have more subheadings and so forth. This post is longer and more detailed than most, but sometimes I just write a post in order to have it there to refer to like a reference for later.

  2. Pingback: The Robot and The Wanderer – Time Management for Musicians, part 2 – Beyond the Notes

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