Episode #28: Does all stress hurt my memory? What’s how’s and why’s- with Grant Shields

Apr 23, 2018

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We have spoken about the effects of stress and memory. This week we will talk about how stress effects memory. FAIR WARNING: This episode is super technical. This will be great for the geeks, nerds, and mechanism seekers among us. BUT HAVE NO FEAR, because practical information does emerge from this episode thanks to our guest’s mastery of this subject.

Grant Shields is a Ph.D. candidate in psychology at Univ of California in Davis working with both Andrew P. Yonelinas in the Human Memory Lab and Brian C. Trainor in the Behavioral Neuroendocrinology Lab. He also works with a previous guest of ours, Dr George Slavich, at the UCLA Laboratory for Stress Assessment and Research.

Grant’s research is aimed at understanding why our cognitive functions fail us when we seem to need them most. In particular, he studies the effects of stress on both memory and executive functions as well as the biological pathways through which those effects occur…and that is exactly what we want to know about.

In this Episode You Will Learn:

What is stress?

In Grant’s research he is speaking about “acute” stress which is a limited, subjective experience of a stressor (eg a car crash). This is distinguished from “chronic” stress which is the subjective experience of an ongoing stressor (eg getting a diagnosis of a terminal disease like Alzheimer’s).

Classically, a stress response is evoked if an event is uncontrollable, unpredictable, ambigious or has a social threat component to it.

Acute stress is completely adaptive. in other words we typically are capable of experiencing this and moving on. Responses to acute stress can be useful. However, these responses can become maladaptive or inappropriate which can in turn be harmful. Chronic stress is not yet known to ever be beneficial.

Phases of Memory

  • -Encoding – the phase of learning something new
    • Stress at encoding can enhance or impair learning and memory. it enhanc
  • Postencoding/consolidation period – last about about 60 minutes just after learning something new
    • Memory for something you just learned can enhanced by stress
  • Retrieval phase or postreactivation phases

What Stress Hormones/Glucocorticoids do to Memory

It isn’t just cortisol that has an impact on memory. Grant explained that, within the hippocampus – an area known to be important for short term memory formation and conversion to long term memory- cortisol’s relationship with norepinephrine in the basal-lateral amygdala to boost memory for information during the period of synergy between cortisol and norepinephrine. As cortisol secretion persists they exert genomic effects within the hippocampus and begin to inhibit the processing and storage (memory) of new information.

Executive Function

  • inhibition – the ability ignore irrelevant information coming into your brain
  • working memory updating – ability to add to what and update your current thinking
  • cognitive flexibility/set shifting – flexibly shift between different kinds of thinking

The Physiologic Costs of Stress

Chronic stress, as stated, give rise to elevated glucocorticoids. Over time glucocorticoids less ability to shut off inflammatory signals. Over time, with chronic stress, develops a chronic state of inflammation, immune system function can become impaired, and autoimmune conditions can be triggered. When glucocorticoids bind in the memory centers of the brain, like the hippocampus, it degrades memory formation.

Practical Info

To improve your memory for newly learned things, consider a brief “healthy stressor” like exercise after you have some thing you want to commit to memory. Exercise promotes memory formation in the brain. Meditation, of course, is protective as well.

Resources Mentioned:

  • To Learn More about Grant’s work find him here 

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