task 6 - sleep

Question 1

stages of sleep divded into the patterns of psychophysiological measures

Answer 1

1. EEG
2. electrooculography (EOG) - measures eye movement
3. electromyography (EMG) - measures muscle electrical activity

Question 2

synchronous EEG activity

Answer 2

if neurons are active about the same time their electrical messages are synchronized and appear as a large clear waved in the EEG data

Question 3

dyssynchronous EEG activity

Answer 3

if neurons are active at random their electrical messages are desynchronized and cancel each other, resulting in small chaotic waveforms without a clear pattern in the EEG data

Question 4

alpha EEg activity

Answer 4

regular, medium frequency waves at 8-12Hz (cycles per second), produced when a person is resting quietly, not particularly aroused or engaged in strenuous mental activity. more prevalent when a persons eye are closed

Question 5

beta EEG activity

Answer 5

irregular, mostly low amplitude waves of 13-30Hz. shows desynchrony, which reflects the active processing of information by many different neural circuits in the brain. desynchronized activity occurs when a person is alert and attentive to the events in the environment or is thinking actively

Question 6

order of sleep waves

Answer 6

beta (14-30 Hz)
alpha (8-13 Hz)
theta (4-7 Hz)
delta (< 3.5 Hz)

Question 7

as we prepare to sleep ___ waves begin to come in at a low-voltage high-frequency waves of alert wakefulness ⇒ as we fall asleep there is a transition to a period of stage 1 sleep

Answer 7

alpha

Question 8

initial stage 1 EEG

Answer 8

→ marked by theta activity (3.5-7.5 Hz) which indicates synchronization of neurons in the neocortex

→ not marked by any significant electromyographic or electrooculographic changes

→ hypnic jerks (muscle contractions followed by relaxation) are experienced in this stage, this can be accompanied with a falling sensation

Question 9

emergent stage 1

Answer 9

→ subsequent periods of stage 1 sleep EEG. marked by theta and beta activity, rapid eye movements (REMs), a loss of tone in the muscles of the body core (paralyzed), high cerebral activity in many brain structures, a general increase in the variability of autonomic nervous system activity

→ occasional muscle twitches happen and there is always some degree of erection

• easily woken up by meaningful stimuli like their name being called. when awaked from REM sleep a person appears alert and attentive

Question 10

STAGE 2

Answer 10

slightly higher amplitude and lower frequency than stage 1 EEG. it is also accompanied with 2 wave forms

sleep spindles; 0.5-2 bursts of 11 to 15Hz waves that occur between 2 and 5 times a minute.

k complexes; sudden, sharp waveforms. spontaneously occur once per minute but can be triggered by noises (unexpected ones)

Question 11

STAGE 3

Answer 11

defined by a predominance of delta waves (the largest and slowest waves) with a frequency of 1 to 2 Hz. because of this it’s also called slow-wave sleep (SWS)

→ deepest stage of sleep

• therefore only loud noises will cause a person to be awake, they will act confused and groggy when awoken (judith during exam season)

Question 12

how long is each cycle

Answer 12

90 mins

Question 13

which stage is most spent in during sleep?

Answer 13

emergent stage 1

Question 14

dreaming

Answer 14

→ REM sleep is like stories and non-REM dreams are more weird and obscure

→ dream content is influenced by the prior period of wakefulness (anxiety affects the emotional context of the dreams)

Question 15

Hobson’s activation-synthesis hypothesis

Answer 15

during sleep, many brainstem circuits become active and send output to the cerebral cortex. Information supplied to the cortex during sleep is largely random and the resulting dream is the cortex’s effort to make sense of these random signals

Question 16

revensuo’s evolutionary theory of dreams

Answer 16

dreaming to stimulate threatening events in order to better predict and respond to threats when we are awake

Question 17

hobson’s protoconsciousness

Answer 17

dream to stimulate any events, not only threatening ones. it is a training mechanism with each dream representing a virtual real-life scenario

Question 18

where do we dream?

Answer 18

→ temporo-parieto junction (both REM and nonREM dreaming) and medial prefrontal cortex lead to dreaming

→ the secondary visual cortex and medial occipital lobe contributes to visual imagery in dreams

Question 19

recuperation theories of sleep

Answer 19

being awake disrupts the homeostasis (internal physiological stability) of the body and sleep is required to restore it

Question 20

adaptation theories of sleep

Answer 20

→ sleep is not a reaction to the disruptive effects of being awake but the result of an internal 24-hour timing mechanism. humans are highly motivated to engage in sleep (carry out brain functions that can only be done in sleep, converse resources, make ourselves less susceptible to incidents in the dark)

consolidation of long term memories, sorting and processing the information throughout the day

Question 21

posterior hypothalamus and midbrain

Answer 21

thought to promote wakefulness

Question 22

anterior hypothalamus and adjacent basal forebrain

Answer 22

thought to promote sleep. when preoptic neurons become active, they suppress the activity of arousal neurons and we fall asleep

Question 23

reticular formation

Answer 23

often called reticular activating system for it’s low level of activity in the reticular formation produce sleep and high levels produce wakefulness

Question 24

ventrolateral preoptic area (VLPO)

Answer 24

contains neurons that connect directly to the many arousal promoting centers. the VLPO neurons inhibit their activity, by shutting down the arousal centers the VLPO promotes sleep

Question 25

circadian rhythm/cycle

Answer 25

a cycle in behavior and physiological processes that repeats itself roughly every 24 hours

Question 26

entrainment

Answer 26

the process of synchronizing a biological rhythm to an environment stimulus

Question 27

zeitgebers

Answer 27

temporal cues in the environment (the light to synchronize the schedule of our circadian cycles

Question 28

free-running rhythms

Answer 28

circadian rhythms in constant environments

Question 29

free-running period

Answer 29

the duration of a free-running circadian rhythm

Question 30

suprachiasmatic nuclei (SCN)

Answer 30

the circadian clock is implemented as a function of the medial hypothalamus which receives light information from the environment and uses it to entertain behaviors to a 24-hour light/dark cycle

Question 31

SCN reveals a direct projection from the retina to the SCN name of pathway?

Answer 31

the retinohypothalamic pathway

Question 32

melanopsin

Answer 32

a special photochemical that facilitates this transfer of info. from the retinal ganglion cells (neurons whose axons transmit info. from the eyes to the rest of the brain)

Question 33

pineal gland

Answer 33

is a neuroendocrine organ that is located just above the thalamus, where the 2 halves of the brain join. in response to input from the SCN, during the night it secretes a hormone called melatonin which controls hormones, physiological process and behaviors that show seasonal variations

Question 34

jet lag

Answer 34

acceleration/deceleration of the zeitgebers that control the phases of various circadian rhythms during east-bound flights (phase advances) and west-bound flights (phase delays)

Question 35

hypersomnia

Answer 35

disorders of excessive sleep or sleepiness

Question 36

narcolepsy

Answer 36

a neurological disorder characterized by severe daytime sleepiness and repeated sleep attacks (brief daytime sleep episodes) and cataplexy (reoccurring losses of muscle tone during wakefulness. often triggered by an emotional experience or by sudden physical effort; caused by massive inhibition of motor neurons in the spinal cord)

• people with narcolepsy often experience sleep paralysis (the inability to move just as one is falling asleep or waking up) and hypnagogic hallucinations (dreamlike experiences during wakefulness)
• associated with lower levels of a neuropeptide called orexin/hypocretin
  • orexin is synthesized by neurons in the posterior hypothalamus. the orexin producing neurons project diffusely throughout the brain but show many connections with the reticular formation
  • high levels of a type of immune cell called T cell, targets hypocretin (suggests that it might be an autoimmune disease)

Question 37

sleep talking

Answer 37

no special association with REM sleep, it can occur during any stage but most often occurs during the transition to wakefulness

Question 38

sleep walking

Answer 38

occurs during slow-sleep wave and never during REM sleep when core muscles tend to be completely relaxed

Question 39

REM sleeping disorder

Answer 39

a sleep disorder characterized by the failure to exhibit paralysis during REM sleep (can cause danger)

Question 40

micro-sleep

Answer 40

→ brief periods of sleep, typically 2-3 seconds during which the eyes close and individuals are less responsive to external stimuli

→ starts occurring after 2-3 days of continuous sleep deprivation

Question 41

REM rebound

Answer 41

when someone has REM-sleep deprivation they have more often than their usual REM sleep for the first 2-3 night. more frequent initiation of REM sleep suggests that there is a certain need for the REM sleep