Neuro Lab Final

What three areas are primarily involved in the stress response?

Voluntary, autonomic, neuroendocrine

What is the voluntary system?

• sends messages to muscles so that we may respond to sensory information

• getting you out of harm’s way

What is the autonomic system?

• sympathetic and the parasympathetic divisions

• causes arteries to shunt more blood to the muscles, allowing a greater capacity for muscular contractions and action

• dilation of the pupils and bronchioles and increased heart rate and blood pressure

• blood flow to the skin, kidneys, and digestive tract is reduced

What is epinephrine?

• The stress hormone epinephrine, also known as adrenaline, is quickly released into the bloodstream

• released from autonomic system

• put the body into a general state of arousal and enable it to cope with the challenge

• sympathetic system

What does the parasympathetic autonomic system do?

• helps regulate bodily functions and soothe the body once the stressor has passed, preventing the body from remaining in a state of energy mobilization too long

• Some actions of the calming parasympathetic division appear to reduce the harmful effects of the emergency sympathetic division’s response to stress

What is the neuroendocrine system?

• maintains the body’s internal functioning

• Various stress hormones travel through the blood and stimulate the release of other hormones, which affect bodily processes such as metabolic rate, growth, development, digestion and sexual function

What is stress?

• any external stimulus that threatens homeostasis — the normal equilibrium of body function

• homeostasis might soon be disrupted.

• Lack or loss of control is a particularly important feature of severe psychological stress, which can have physiological and pathological consequences.

• The most harmful consequences result from the chronic aspects of the stress response

What is the HPA axis?

• one endocrine output of a central corticotropin releasing hormone (CRH) network that coordinates autonomic, neuroendocrine, behavioral, and immune responses following alterations in homeostasis

• Inhibitory feedback from glucocorticoids secreted by the adrenal cortex and circadian activity of the hypothalamus and other brain regions regulate the magnitude and duration of HPA axis activity

• regulated at the level of the hypothalamus

How does the HPA respond to stress?

• The HPA axis extends the fight-or-flight response by providing a slower, more sustained neuroendocrine system response to manage stress.

• generates hormones like cortisol to prolong the body's energy mobilization as well as to prepare it for sustained stress and recovery

• the hypothalamus releases CRH, which in turn prompts the anterior pituitary gland to release adrenocorticotropic hormone (ACTH), which in turn signals the adrenal cortex to release cortisol

What are the three gland components that respond to stress?

the hypothalamus, pituitary, and adrenal glands make up a dynamic three-gland component of the endocrine system that helps manage the body’s response to stress.

What is allostasis?

• The chronic state of re-establishing or maintaining homeostasis

• The wear and tear on the organism resulting from continuous maintenance of homeostasis is the allostatic load

What are some diseases that affect the HPA axis?

psychiatric, eating, metabolic, gastrointestinal, and inflammatory disorders

What are the living conditions after jugular vain cannula surgery?

housed alone to prevent them from biting or chewing the blood collection cannulas of other rats and to prevent them from re-injuring surgical areas because of fighting or playing

• rats perceive being housed alone as a very stressful experience, and they much prefer to be in a group

What hormones increase during or after stress?

The pituitary hormone, ACTH, and the adrenal gland hormone, corticosterone

Where was Dr. Rhodes first introduced to Biodots?

Allegheny General Hospital in Pittsburgh

What are Biodots?

• Biodots produce biological feedback about what’s going on inside your body

• The information that these devices provide can let you know your stress status, and potentially whether or not you have positively or negatively impacted that stress status via interventions

What are some physiological responses to stress and the HPA axis being activated?

• increasing heart rate, inducing the bronchioles and pupils to dilate, and constricting blood flow to certain areas of the body, particularly to the digestive tract and skin

What causes the Biodot to turn black?

reduction in blood flow to the skin during stress causes the temperature of the skin to decrease, thus influencing the coloration of the Biodot — turning it black

How do you know if meditation relaxed you after feeling stress?

If the Biodot turned from black to blue you’d know that the temperature just beneath the surface of your skin had increased and (by deduction) you would know that your capillaries had opened up, that the blood flow had improved, and that you had activated the relaxation (parasympathetic) response

What are some known ways to reduce stress?

• exercise, mindfulness and relaxation techniques, dietary factors like comfort foods, and certain medications used in the treatment of anxiety and depression will reduce stress and thereby positively influence HPA axis activity

• Tactile stimulation appears to be a relaxation strategy that may increase attentiveness, concentration, and focus

Who invented the battery?

Count Volta, among other things, invented the battery and had a unit of electrical measurement named in his honor (the Volt)

Which way does electricity flow?

negatively charged to parts of your body that are positively charged

What is emotion?

any relatively brief conscious experience characterized by neurological activity leading to a high degree of pleasure or displeasure

Who developed the wheel of emotions?

Dr. Robert Plutchik

• Plutchnik believed that primary emotions could blend to form the full spectrum of human emotional experience. For example, interpersonal anger and disgust could blend to form contempt

What is the limbic system?

hypothalamus, cingulate cortex, hippocampus, and amygdala, among other structures; some areas of the cerebral cortex

What is the amygdala?

• critical for emotion

• emotional learning

• rewarding or aversive events

• fMRI have demonstrated that normal individuals have increased amygdala activity when viewing images depicting facial expressions

Where is the amygdala?

• temporal lobe

• processing of memory, decision-making, and emotional reactions

What is the medial nucleus of the amygdala?

sense of smell and pheromone-processing. It receives input from the olfactory bulb and olfactory cortex

What is the lateral nucleus of the amygdala?

which sends impulses to the rest of the basolateral complexes and to the central nucleus, receives input from the sensory systems, including the visual, auditory, and chemosensory systems

What is the central nucleus of the amygdala?

main outputs for the basolateral complexes, and are involved in emotional arousal in mammals

Electrocardiography (ECG) Recordings

• As an action potential is propagated through the myocardium, tiny electrical currents spread throughout the body resulting in potential differences (voltages) between different body surface areas

• (ECG) is simply a recording of those potential differences.

• ECG is an average of all the electrical events that occur simultaneously within the heart

What is Einthoven’s Triangle?

• an imaginary formation of three limb leads in a triangle used in ECG

• The triangle itself is formed by the two shoulders and the lower limbs. We will be using Lead II in our ECG recordings

Electromyography (EMG) Recordings from Facial Musculature

• When a motor unit is activated, the component muscle fibers generate and conduct their own electrical impulses that ultimately result in contraction of the fibers

• The detection, amplification, and recording of changes in skin voltage produced by underlying skeletal muscle contraction is called electromyography

Facial Muscular System

• the only place in our body where muscles are either attached to a bone and facial tissue (other muscles in the human body often connect to two bones), or to facial tissue only such as the muscle surrounding the eyes or lips

• facial muscle activity is highly specialized for expression - it allows us to share social information with others and communicate both verbally and nonverbally

• Almost all facial muscles are innervated by a single cranial nerve (VII), the facial nerve

• The facial nerve emerges from deep within the brainstem, leaves the skull slightly below the ear, and branches off to all facial muscles like 
 a tree.

Motor cortex

• consciously controlled and intentional facial expressions

What measures emission of cortisol and stress hormones?

the amygdala

What are the most common facial EMG sites?

• the right and left corrugator supercilia muscles and the right and left zygomaticus major muscles

• small, narrow, pyramidal muscles near the eye brow, generally associated with frowning

• corrugator draws the eyebrow downward and towards the face center, producing a vertical wrinkling of the forehead

• This muscle group is active to prevent high sun glare or when expressing emotions suffering

• The right and left zygomaticus major muscles extend from each cheekbone to the corners of the mouth and draw the angle of the mouth up and out, typically associated with smiling

What are other muscles involved in facial expressions?

orbicularis oculi (closing the eyes, blinking), the procerus (flaring the nostrils, movement of eyebrows downward, as in anger), and the frontalis (raising the eyebrows, as in surprise or fear)

Electrodermal (EDA) Recordings

• skin conductance level (SCL)

• study the efferent responses to emotional stimuli

• extremities such as the fingers, palms of the hands, and soles of the feet

• galvanic skin resistance (GSR) and the galvanic skin potential (GSP). (Galvanic is defined as electrical changes induced by rapid chemical reactions.)

What is GSR?

When a feeble electric current is steadily applied between two electrodes placed about an inch apart on the palm of the hand, the recorded electrical resistance between them

What is GSP?

if the palm electrodes are connected to a suitable voltage amplifier, but without any externally applied current, the voltage measured between them

What is the galvanic skin response?

The combined changes in the GSR and GSP related to the emotion of the subject constitute the galvanic skin response

What is the basis of galvanic skin response?

a change in autonomic tone, largely sympathetic, occurring in the skin and subcutaneous tissue in response to a change in the affective state of the subject

• Changes in peripheral autonomic tone alter sweating and cutaneous blood flow, which in turn change GSR and GSP

Example of a response that influences GSR

the vasodilation of cutaneous blood vessels of the face (blushing) and increased sweating that often occur in the emotional state of embarrassment

What is a polygraph?

• The detection and recording of the galvanic skin response is often combined with the detection and recording of other autonomic-dependent psychophysiological variables such as heart rate, respiratory rate, and blood pressure

• The device that detects and records these variables is called a polygraph

What are reflexes?

• rapid, predictable, involuntary motor responses to stimuli

• mediated over neural pathways called reflex arcs

What are the five essential components to reflex arcs?

1. the receptor reacts to a stimulus

2. the sensory neuron conducts the afferent impulses to the CNS

3. the integration center consists of one or more synapses to the CNS

4. the motor neuron conducts the efferent impulses from the integration center to an effector

5. the effector, muscle fibers or glands, respond to the efferent impulses by contracting or secreting a product, respectively

What type of reflex arc is the knee-jerk reflex?

simple, two neuron, monosynaptic

What depends the time of reflexes?

• more synapses encountered

• delay of reflex may occur at the synapse, makes more synapses in a reflex pathway, takes more time

What are decerebrate animals?

brain has been destroyed

What are spinal reflexes?

initiated and completed at the spinal cord level such as the flexor reflex

Autonomic reflexes (visceral)

mediated through the autonomic nervous system and are not subject to conscious control

• smooth muscle, cardiac muscle, glands of body

• digestion, elimination, blood pressure, salivation, sweating

Somatic reflexes

• skeletal muscle; somatic division

• withdrawal of hand from hot object

• stretch, crossed extensor, superficial cord, corneal, and gag reflex

Stretch reflexes

• maintain posture, balance, locomotion

• tapping a tendon- stretches muscle tendon is attached to

• afferent fibers (from muscle spindle) also synapse with interneurons (association neurons) controlling antagonist muscles

Reciprocal inhibition

• inhibition of an antagonist muscle after a reflex

• causes antagonist muscles to relax

• prevents them from resisting contraction of stretched muscle caused by reflex arc

What sends impulses to higher brain order?

dorsal white columns

• advise of muscle length, speed of shortening, information needed to maintain posture

Are stretch reflexes hypoactive or hyperactive?

• both

• hypoactive: absent in peripheral nerve damage or ventral horn disease

• hyperactive: corticospinal tract lesions

• absent in deep sedation and coma

Crossed extensor reflex

• flexor reflex followed by extension of opposite limb

• withdrawal arm when grabbed by a stranger

Reflexes completed at spinal cord examples

stretch and crossed extensor reflexes

Superficial cord reflexes

• abdominal, plantar, cremaster

• result from pain and temp changes

• initiated by receptors in skin and muscosae

• upper motor pathways and cord reflex arc

Plantar reflex

• cutaneous receptors in sole of foot

• toes flex and move together

• damage to pyramidal (corticospinal tract) gives Babinski sign (toes flare up)

• newborns have babinski sign due to incomplete myelination

Corneal reflex

• trigeminal nerve (V)

• absense of this shows damage to brain stem

Pupillary light reflex and consensual reflex

• retina is the receptor

• optic nerve (II) is afferent fibers

• oculomotor nerve (III) is efferent impulses to eye

• smooth muscle of iris is effector

Contralateral vs ipsilateral response

• contralateral: consensual

• ipsilateral: pupillary light

Ciliospinal reflex

• stroke skin on left back neck

• pupils should dilate

• stimulates sympathetic nervous system