Stress and Health What is a stressor?A stressor is anything that alters or disturbs ones allostatic balanceWhat is allostasis?Allostasis is an adaptive way in which the body changes its set points in response to changes in its life or changes in the environment. For example your body needs to be in a different state when you are getting into a fight versus when you are trying to go to sleep.What are the 3 stages of a stress response?1. Alarm- the sympathetic nervous system is activated by some stressor2. Resistance- your SNS is partially suppressed, while activity in your Hypothalamus-Pituitary gland-Adrenal Cortex or (HPA) axis is increased-releasing cortisol (stress hormone) and other hormones involved in maintaining alertness and increasing the function of your immune system.3. Exhaustion- after a while the nervous system and the immune system are spent. Your body has been working hard to handle this new stressor and it gave its’ best shot. The person is tired and vulnerable to illness because of the suppressed immune system.What is the role of the sympathetic NS in the stress response? The sympathetic nervous system prepares the body for brief emergency responses to stressors. This results in the fight or flight response.What is the HPA and what is its role in the stress response?The HPA is the Hypothalamus, Pituitary gland, and Adrenal Cortex. Activation of the hypothalamus induces the anterior pituitary gland to secrete adrenocorticotropic hormone(ACTH). The ACTH stimulates the adrenal cortex to secrete cortisol which enhances metabolic activity and elevates blood sugar levels and the levels of other nutrients. Cortisol is referred to as the stress hormone. Why do you feel terrible during finals week?Cortisol helps the body use its energy to fight a difficult situation. Over short periods of time, cortisol actually improves attention and memory formation. However, a long exposure to increased levels of cortisol seen during finals week actually impair memory and immune activity leaving the student vulnerable to sickness and poor performance. What are some effects of long-term stress?Long-term stress can cause damage to the hippocampus, which is responsible for memory. Increased cortisol levels are detrimental to the hippocampus. Stress can decrease sex drivein women, decrease sexual performance in men, and even delay the menstrual cycle.Poor immune function caused by too much stress can leave a person chronically sick. Increased cortisol can increase the blood sugar in the body, which can ultimately cause kidney damage, brain damage, and heart disease. What are some factors that affect the stress response?• Individual’s perception of their own ability to cope with stress• Intensity of the stressor (novel environment vs. life-threatening situation)• Individual’s control over the stressor (watch the national geographic special referenced in a few slides)• Duration of stressor• Social support• Personality traits (individuals with high anxiety are more likely to show impaired memory after stressor)• Gender (males more affected than (young) females…some measures improve in females!)• Age (older more vulnerable to deleterious effects of stress than younger; early stress might not show cognitive effect until later in life)How does stress affect the hippocampus and amygdala?Hippocampus and amygdala are 2 brain regions w/ lots of receptors for cortisol.-Increased cortisol makes hippocampus neurons more vulnerable which results in Hippocampal damage.a) Chronic infant stress leads to deceased hippo plasticity & impaired spatial memory in adulthood.b) Explicit memories (consolidated by hippocampus) are esp. vulnerable to stress; implicit memories are not (sometimes opposite effect!)-Amygdala increases branches, and other brain regions that do implicit learning (like cerebellum) are not as affected by stress.PTSD: what are the symptoms? What types of events can precipitate it? Why doesn’t everyone who is exposed to such a stressor develop PTSD?Symptoms: Flashbacks and nightmares about event, Avoidance of reminders of event, and Exaggerated arousal in response to noises or other stimuli.Type of events that precipitate it: Severe injury or threat, Witness others harmed or killed, Soldiers, victims of rape, kidnapping or torture, car crash survivors, sudden loss of loved one Why doesn’t everyone in such situations develop PTSDPTSD victims have smaller hippocampus. PTSD patients w/ identical twin & no trauma or PTSD…twin had smaller hippocampus too…suggests small hippocampus came before PTSD and is not result of PTSD. PTSD victims have lower than average cortisol levels at time of event and 2 weeks laterMaybe people w/ low cortisol are ill-equipped to handle extreme stressLearning and Memory What is an engram, and what were Lashley’s critical mistakes in looking for the engram?An engram is a physical representation of a memory, an actual structure. Think of it as a thumb drive in your brain that stores all the information of your memory. Lashley assumed that memories were all stored in the cortex and that all memories are physiologically the same. Modern thought suggests that memories are stored and distributed among a variety of neural systems, not just the cortex, yet some types of knowledge may be centered around one particular area. Different types of memories such as visual-spatial and smell are stored in different parts of the brain.What are implicit memory and explicit memory? What brain regions are important for each?Implicit memory- Skills and habits, emotional associations, and conditioned reflexes. Implicit memories are memories that you use that are influenced by recent experiences that you don’t even know you are applying to your life. The Stratum, motor areas of cortex, and cerebellum important for skills and habits. Amygdala important for Emotional associations. Cerebellum important for conditioned reflexes.Explicit memory- Knowing facts and remembering events. Who won the 1998 World Series? What is a neuron?The hippocampus, medial diencephalon, and nearby cortical areas are important for explicit memories.What are some differences b/t short-term memory (working memory) and long-term memory? What brain region is important for working memory?Short-term memory fades quickly unless rehearsed, long term lasts indefinitely. Short termhas a small capacity, long term has infinite capacity. The prefrontal cortex
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