Ch 18 - Stress & Anxiety

What is the prefrontal cortex's role in the stress response?

complex "human behaviors:; executive fns

What is the fn of the paraventricular nucelus of the hypothalamus?

fluid balance, milk let-down, childbirth, autonomic and anterior pituitary control

What are some other pertinent factors that influence the consequences of stress?

- Genetics - lack of control - unpredictability - access to outlets for frustration - level of intelligence - dominance factor - poverty

What did Cannon propose?

- homeostasis (physiological mechanisms constantly maintain the internal balance via feedback loops). - Went beyond physiological to psychological. -Described fight or flight. -Sympathetic activation.

What are 3 systems that communicate w the hypothalamus?

- limbic system -sensory, autonomic and cortical circuits -neuroendocrine system see slide 15

What were Selye's contributions?

- redefined stress (nonspecific response of the body to any demand upon it) - identified HPA axis -recognizes deleterious effects of chronic stress through General Adaptation Syndrome model

What are the responsibilities of the pituitary gland during the stress response?

- releasing hormones from hypothalamus -secretion into capillaries - Stimulation of pituitary cells: release their hormones into bloodstream - List of hormones receives: cortico-releasing hormone--> ACTH GnRH--> FSH/LH TRH-->TSH Prolactin GH

What happens under stress conditions (bottom-up)?

-Amygdala activates stress pathways -Indirectly increases amount of NE in the PFC thereby dysregulating PFC fn. Sensitizes further the amygdala to threatening stimuli.

What happens under non-stress conditions (top-down)?

-Areas of the PFC regulate emotions, thoughts, and bx. These areas connect w other structures to regulate responses and bx and connect with each other to regulate decision-making, planning, and organizing. - DLPFC connects w sensory & motor cortices; regulates attention, thought and action - rlPFC inhibits inappropriate motor responses - VMPFC has extensive connections w subcortical structures (eg hypothalamus, amygdala) and regulates emotional responses -DMPFC is associated w error monitoring and reality testing

Chronic stress does what to the PFC?

-Structural changes in PFC neurons -reduction in dendrite length -branching and density of spines

What is the locus coeruleus' role in the stress response?

-many fns, including arousal, vigilance, and attention -plays important role in PFC fn -contains most prominent group of noradrenergic neurons -NE release increases in the PFC during exposure to acute stress; working memory related to NE in an inverted U-form. Optimal amount of NE (alert, non-stressed) enhances WM. Excess NE (or too little) impairs WM (partially mediated by binding to lower affinity alpha1 and beta1 receptors) -PFC can also regulate the LC activity (therefore regulating its own NE inputs)

What are the 5 physiological structures that help maintain homeostasis?

1. Organs & built-in reflexes- can regulate themselves without higher levels of control required. 2. ANS & endocrine system- provide communication from the CNS to individual organs. 3. Brainstem- helps regulate organs via autonomic outputs and reflex centers. 4. Hypothalmaus- regulates ANS and endocrine messaging; coordinates actions of brainstem autonomic nuclei. 5. Higher brain centers- obtain information from our external world that can be used to alter hypothalamic and brainstem activity.

ANS drives the WHAT physiological response to a stressor?

ACUTE

Chronic stress exposure produces branching of dendrites in WHAT?

AMYGDALA

Hypothalamic bidirectional (and a couple of efferent-only) connections with limbic system structures and brainstem help to maintain homeostasis via control of the WHAT and WHAT?

ANS & endocrine system (HPA) Controls blood pressure/electrolyte system, regulate body temp, metabolic rate and energy metabolism, controls reproductive processes, drives physiological and bx aspects of stress response

What are characteristics of inflammation in relation to stress?

Chronic inflammation is the overactivation of immune inflammatory processes, and has been examined in relation to various physical conditions. Inflammation occurs in response to a threat that the body needs to attend to (Eg response to an injury); in chronic responses the immune system continues to activate cells and chemicals that sustain inflammation.

There is a relationship between activation of the HPA axis and inflammation that probably drives the link between WHAT and WHAT?

Chronic stress and physical conditions; Under normal conditions, cortisol released as a result of HPA activation serves to reduce immune response and related inflammation; chronic stress conditions impair this response. Rather than circulating levels of cortisol, how tissue responds to cortisol may be more important. **Glucocorticoid receptor (GR) resistance may be a result of chronic stress. GR resistance may lead to poor control over inflammatory responses and greater expression of disease symptoms.

What is CRH?

Cortico releasing hormone is the primary hormone influencing release of aCTH; CRH fibers found in other CNS targets to integrate emotions into behavioral and physiological responses.

What are the prolonged effects during the stress response?

Cortisol, vasopressin, thyroxine, etc. (minutes, hours, days... even weeks). HPA axis, hypothalamus/posterior pituitary, hypothalamus/thyroid gland.

What are the intermediate effects during the stress response?

Epinephrine is released with some norepinephrine (20-30 seconds). Hypothalamus directly innervating adrenal medulla.

What does glucocorticoids (eg cortisol) do?

Glucose metabolism, anti-inflammatory, stress response, synthetic glucocorticoids. Cortisol helps to ready the body for action in fight-or-flight response. Receptors for cortisol are founds throughout the brain and body.

People with PTSD show WHAT of amygdala during fear conditioning and extinction experiments?

HYPERACTIVITY

WHAT of the amygdala predict mood and anxiety responses to stressors up to 4 years later?

HYPERACTIVITY of the amygdala

People with PTSD who show deficits in extinction show reduced activity of the WHAT and WHAT?

Hippocampus and VM PFC

What are the immediate effects during the stress response?

Norepinephrine is released from the SNS (2-3 seconds). Organs and muscles innervated by pons (LC) hypothalamus via SNS.

What is characteristic of the anterior pituitary?

Relatively slower and more prolonged response to stressor.

Anxiety is associated with ineffective top-down inhibition from WHAT to WHAT, possibly associated reduced ability to evaluate emotional meaning to stressors?

PFC to AMYGDALA

Early studies showed stress impairs WHAT cognitive fns?

PFC-mediated

Cells in which nucleus of the hypothalamus regulates the ANS?

Paraventricular nucleus (PVN)

What is the stress response?

Physiological resources are activated, and responses are produced to manage physical and psychological challenges. Serves as an adaptive process, however, chronic stress is bad.

Cluster of physiological changes associated with WHAT or WHAT threat?

REAL or PERCEIVED

What does prolactin do during the stress response?

Released by anterior pituitary regulates reproductive physiology; role in stress response not well understood- perhaps regulates/ fine-tunes stress response or buffers immunosuppression of stress response.

What does glucagon do during the stress response?

Released by pancreas regulates carbohydrate dispersion.

What does vasopressin do during the stress response?

Released by posterior pituitary regulates kidney function and water volume.

What does endorphins do during the stress response?

Released by the anterior pituitary help regulate pain perception and reproductive physiology.

What does thyroxine do during the stress response?

Released by thyroid gland regulates cell metabolism (how much oxygen cells use and transforming glucose and oxygen into energy) and enhances the body's sensitivity to the catecholamines.

Studies exposing subjects to WHAT support the GR resistance model?

Rhinovirus; In healthy participants, greater stress exposure was associated with greater GR resistance. Baseline GR resistance predicted risk of developing cold symptoms in subjects who had experienced significant life stressors and amount of proinflammatory cytokines released as a result of the infection; cortisol (HPA response) was unable to regulate appropriately the cytokine response. Stress and GR resistance are associated with increases in pro-inflammatory cytokine levels.

WHAT response is a universal biological response?

STRESS response

TRUE or FALSE: Other CNS structures are involved with ANS activity?

TRUE

Both SNS and PNS pathways consist of BLANK nerve sequences.

TWO; Slide 18

What does the Yerkes-Dodson Law and Hebb propose?

We perform best under optimal levels of arousal

How does the adrenal gland contribute to the stress response?

When stimulated by ACTH, produces adrenocorticoids: glucocorticoids, mineralocorticoids, and sex steroids.

What is Selye's general adaptation syndrome?

alarm, resistance, exhaustion; the body's nonspecific response to major stressors that are difficult to cope with; These three stages of physiological reactions to noxious events lead to the depletion of physical defenses against stress leading to high blood pressure, heart disease, etc.)

What was McEwen's contribution?

allostatic load- "wear and tear" of chronic stress due to sustained elevated glucocorticoid levels.

WHAT coordinates activity so that increased activity in one branch (ie sympathetic/parasympathetic) inhibits activity in the other?

brainstem nuclei

What is the fn of the dorsomedial nucelus of the hypothalamus?

emotion (Rage)

What is the fn of the mammillary nucelus of the hypothalamus?

emotion and short-term memory

What does HPA stand for in HPA axis?

hypothalamus, pituitary, adrenal; This is the hypothalamic-pituitary adrenal system (HPA)

The consequences of stress must be considered within the context of BLANK BLANK

individual differences

What is the hippocampus' role in the stress response?

learning, memory encoding/consolidation.m spatial navigation Encodes complex contextual environmental info that is associated with threat; serves as a source of negative feedback to the HPA axis via glucocorticoid receptors indirectly inhibits HPA axis hippocampus and PFC important in fear extinction

Individuals with low anxiety exhibit greater functional connectivity between WHAT and WHAT?

mPFC and amygdala

What did Bernard propose?

milieu interieur (organisms maintain a constant environment); enviro is carefully regulated, organism compensates in ways to maintain that balance

What is eustress?

positive stress that motivates you

What is the amygdala's role in the stress response?

processing/regulation of emotion; mediating affectively influenced memories detects threats, mounts physiological and behavioral responses to avoid threats (via central nucleus), establishing memories to predict and respond appropriately to future threats learned fear responses

- - - - - may predispose soldiers to PTSD?

smaller amygdala gray matter volume

Chronic stress exposure will lead to WHAT changes in the hippocampus?

structural