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Chronic stress impairs spatial memory in low-arousal tasks
*High arousal conditions may MITIGATE the negative effects of stress*
What does the Yerkes-Dodson curve show?
That epinephrine's effect on memory follows an inverted U-shaped curve:
- Low and high levels impair memory
- Moderate levels enhance memory
What is general adaption syndrome?
The finding that diverse stressors trigger similar physiological stress reactions
What are the two different CRH receptors?
Crh1: Receptor knockout mice exhibited reduced anxiety and altered stress responses
Crh2: Receptor activation suppresses food intake and contributes to stress-induced appetite suppression
How does estrogen affect depression in women?
Estrogen treatment improves mood in women with severe depression
*Women are at a higher risk for depression than males BOOOOOOO
High corticosterone levels correlate with more errors in spatial tasks
FUN FACT: RU 38486 is a glucocorticoid receptor ANTAGONIST. It can improve performance in spatial tasks
What is the optimal epinephrine level for avoidance memory in rats?
1500 pg/ml
What are the 4 physiological responses described in the Reactive Scope Model?
1. Predictive Homeostasis (Daily and seasonal variations in biological mediators)
2. Reactive Homeostasis (Necessary fluctuations to respond to immediate threats)
3. Homeostatic Overload (Excessive responses leading to long-term health risks)
4. Homeostatic Failure (Insufficient responses leading to short-term health risks)
What is one of the causes of Alzheimers?
Reduced brain insulin receptors
What are the effects of chronic steroid use on aggression?
In males: effect varies by steroid
In females: increased aggression with androgen
*Decreased serotonin signaling in aggression-regulating brain areas -> increase impulsivity and aggression
I was just diagnosed with DYSLEXIA. What part of my brain is affected?? Be SPECIFIC!!
The ANGULAR GYRUS of the Inferior Parietal Lobule!!!
What "path" does Epinephrine follow to enhance memory?
Beta-noradrenergic receptors -> neurons in the vagus nerve -> nucleus of the solitary tract -> Amygdala
What theory suggests that epinephrine secretion increases in response to stressors to facilitate adaption?
Cannon's Emergency Theory
What does Streptozotocin do? How does it affect memory in RATZ?
It induces diabetes and cognitive impairment in rodents
*Phlorizin enhances memory performance in diabetic rats
How is cortisol regulation impacted in depression? (This one is a doozy)
~50% of depressed patients show excessive cortisol secretion
This highlights the chronic HPA axis dysregulation in depression
This occurs because of a failure of Dexamethasone in suppressing cortisol secretion
Circadian rhythm is disrupted in depressed patients
Sensitization vs Habituation?????????
Sensitization: Increased response to a stimulus after repeated exposure or after a strong initial stimulus
Habituation: Decreased response after repeated exposure to a harmless stimulus
What is sAA? How does it relate to memory? Does it have a higher response in men or women?
Salivary alpha-Amylase
It is a biomarker for adrenergic activity
- Increased sAA after emotional image viewing is linked to improved emotional memory recall
Women have a stronger response
What happens in the HPA axis?
The hypothalamus releases CRH, stimulates ACTH, and produces beta-endorphins from the anterior pituitary. This leads to corticosterone secretion from the adrenal cortex.
Diabetic Rats and LONGGGG TERMMM POTENTIATIONNNN
LTP enhances neuronal connectivity (linked to learning)
Diabetic rats show impaired hippocampal LTP
*Insulin treatments improve the impairments*
HPA hallmark of depression?
Impaired HPA axis negative feedback
Active Avoidance vs Passive Avoidance?? Tell me about them. AND how they differ in males/females
Active avoidance: A form of associative learning where an animal must engage in a behavior to avoid an unpleasant stimulus
*Females learn active avoidance tasks faster*
Passive: Involves the inhibition of behavior that the animal would otherwise engage in to avoid an unpleasant stimulus
*Males perform better in passive avoidance tasks*
What does the Glucose Hypothesis of Memory Enhancement say?
That glucose enhances acetylcholine release
Inverse U shaped dose-response -> optimal memory enhancement at 100 mg/kg glucose
*Delayed glucose injection ineffective*
What are the two types of corticosteroid receptors in the hippocampus? What do they do?
Type I (MRs): Engage under baseline conditions, maintaining homeostasis
Type II (GRs): Engage during stress, providing negative feedback to regulate glucocorticoid levels
Estrogen and memory? How are they related?
Estradiol enhances memory - particularly in difficult tasks
In rats, both low and high doses of estradiol improves choice accuracy in females
Thyroid findings in depression
Depressed patients may show:
- High levels of thyroid antibodies
- Elevated TRH in cerebrospinal fluid
- T3 influences serotonin pathways - can be used in SSRI therapy