Adrenaline and Memory

Do people with smaller amygdalas remember stressful events as clearly as people with regularly sized ones?

In most cases, we all remember acutely stressful times in our lives more clearly than a lot of other memories (“acutely” meaning immediately stressful, for example a haunted house or a near-death experience). These acute stressors lead to a surge of adrenaline that is to do more with our base instincts than any conscious thought. The amygdala plays a large part in this, and does lead to more clear memory of the stressful experience. As Cahill and McGaugh (1998) have explained, the link between the amygdala and memory is not causal, but its activation is what leads to these distinctly clear memories.

Does this mean that those with smaller amygdalas remember acutely stressful events less clearly, then? According to Welch, et al. (2009) people with learning disabilities and a small amygdala are more susceptible to suffering from schizophrenia. Interestingly, this could support a link between the amygdala and memory. Those that cannot remember will inevitably find it difficult to learn, so those with smaller amygdalas would naturally suffer from disorders in learning. This is supported by Exner, et al. (2004), who found that those in their sample of people with schizophrenia and smaller amygdalas characteristically had trouble learning.

So there is a definite link between the amygdala and memory, but is there a precise link between the two?

References

  • Cahill, L., & McGaugh, J. L., (1998). Mechanisms of emotional arousal and lasting declarative memory. Trends in Neurosciences21(7). 294-299.
  • Exner, C., Boucsein, K., Degner, D., Irle, E., & Weniger, G, (2004). Impaired emotional learning and reduced amygdala size in schizophrenia: a 3-month follow-up. Schizophrenia Research, 71(2-3). 493-503.
  • Welch, K. A, Stanfield, A. C. The link to this journal article no longer works. I cannot find it anywhere else, so cannot finish citing it. Here is the link: http://journals.cambridge.org/abstract_s0033291709990870
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2 thoughts on “Adrenaline and Memory

  1. Really interesting blog, It certainly got me thinking! I understand that there is a definite link between the amygdala and memory, but I am unsure as to whether there is a precise one. I believe that it is one of them situations where no cause or effect can be justified.
    It appears that when memories are being consolidated, the emotional arousal of the memory affects the strength of retention of the memory (1). So it could be argued that the size of the amygdala may not have a direct link upon memory, it may be other factors such as the emotional link to the memory.
    (1) http://www.sciencedaily.com/releases/2006/02/060202182107.htm

  2. It’s not just stressful events which activate the amygdala, Hamann, Ely, Grafton and Kilts (1999) found that pleasant or aversive events were better remembered than neutral ones. Through PET scanning, they discovered that amygdala activity whilst memories are being encoded is correlated with increased episodic recognition memory. Pleasant and aversive events, such as a near-death experience, would give emotional involvement. So, as you’re asking whether people with smaller amygdalas would remember stressful events less clearly, this could be applied to pleasurable events too – for example the birth of their child etc.

    Hamann, S.B., Ely, T.D., Grafton, S.T., & Kilts, C.D. (1999). Amygdala activity related to enhanced memory for pleasant and aversive stimuli. Nature Neuroscience, 2, 289-293. doi:10.1038/6404

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