Flashcards in Exam #3 Deck (57):
Why do we sleep? (4)
Decreasing metabolism. (Energy Conservation).
Cellular maintenance, including neurons.
How do we study sleep
EEG's give a recording of the brain's spontaneous electrical activity over a short period of time, usually 20–40 minutes, as recorded from multiple electrodes placed on the scal
History of understanding of sleep cycles (4)
Your cycle of wakefulness and sleep is generated internally.
During the paradigm of behaviorism, this idea was resisted (i.e. behaviorism requires external stimuli to elicit any response).
In the face of evidence this outlook would eventually become abandoned.
We now understand that the 24 sleep/wake cycle is an innate function of the brain.
Endogenous cycles (4)
Generated from within
Animals have circannual cycles (birds migrate, hibernation, animals store food for winter)
All animals produce endogenous circadian rhythms, internal mechanisms that operate on an approximately 24 hour cycle.
Change as a function of age.
Circadian Rhythms also manage what?
Also regulates the frequency of eating and drinking, body temperature, secretion of hormones, urination, and sensitivity to drugs. Can differ between people and lead to different patterns of wakefulness and alertness.
Free Running Rhythm
is a rhythm that occurs when no stimuli resets it.
a term used to describe any stimulus that resets the circadian rhythms.
Ex: Sunlight/artificial light is the primary one.
Exercise, noise, meals, and temperature are other zeitgebers.
What makes Circadian Rhythms? (3)
1. The Suprachiasmatic nucleus (part of hypothalamus)
2. Genes that produce certain proteins
3. Melatonin levels
Facts about the SCN (3)
S- Synchronicity gone with damage
C- chiasm (above)
N- Not the thalamus
The suprachiasmatic nucleus (SCN) is part of the hypothalamus and the main control center of the circadian rhythms of sleep and temperature.
Located above the optic chiasm.
Damage to the SCN results in inconsistent body rhythms that are no longer synchronized to environmental patterns of light and dark
How light resets the SCN (3)
For all mammals, the SCN receives input from specialized ganglion cells in the retina.
These cells use specialized pigment called melanopsin.
Respond to the average amount of light, not instantaneous changes in light.
2 genes responsible for Circadian Rhythms
Period - produce proteins called Per.
Timeless - produce proteins called Tim.
The SCN regulates waking and sleeping by controlling activity levels in other areas of the brain.
The SCN regulates the pineal gland, an endocrine gland located posterior to the thalamus.
The pineal gland secretes melatonin, a hormone that increases sleepiness
is characterized by an ability to go from completely awake to REM sleep, and consistent daytime sleepiness.
Causes of Narcolepsy (2)
Appear to be strongly genetic. Abnormality in chromosome 6 area called HLA complex.
Correlation between narcolepsy and gene variation for the neurotransmitter orexin, which are involved in controlling appetite and sleep.
Describe the 3 NREM sleep cycles
Stage 1: slow eye movement , Theta Waves
Stage 2: no eye movement, sleep spindles and K complexes waves.
Stage 3; deep sleep, slow waves, delta waves
Sleep stage 1
- Stage 1 sleep is when sleep has just begun.
The EEG is dominated by irregular, jagged, low voltage waves.
Sleep stage 2
Sleep spindles - 12- to 14-Hz waves during a burst that lasts at least half a second.
K-complex - a sharp high-amplitude negative wave followed by a smaller, slower positive wave.
REM Sleep (4)
AKA Paradoxical Sleep
Rapid eye movement sleep (REM), aka paradoxical sleep, are periods characterized by rapid eye movements during sleep.
Characterized by irregular low voltage fast waves indicative of increased neuronal activity.
Heart rate, blood pressure, and breathing are more variable in REM than in stages 2 and 4.
strange pattern of sleep cycles (8)
1. When one falls asleep, they progress through stages 1, 2, 3, and 4 in sequential order.
2. After about an hour, the person begins to cycle back through the stages from stage 4 to stages 3 and 2 and than REM.
3. The sequence repeats with each cycle lasting approximately 90 minutes.
4. Stage 3 and 4 sleep predominate early in the night.
5. The length of stages 3 and 4 decrease as the night progresses.
6. REM sleep is predominant later in the night.
7. Length of the REM stages increases as the night progresses.
8. REM is strongly associated with dreaming, but people also report dreaming in other stages of sleep.
Reticular Formation (4)
The reticular formation is a structure of the medulla that extends throughout the brain and is responsible for arousal.
Axons release glutamate and acetylcholine.
This system promotes wakefulness and cellular arousal.
Stimulation of the ponomesenchephalon wakes sleeping individuals and further wakens those whom are awake.
Locus Coeruleus (5)
The locus coeruleus (dark blue place) is small structure in the pons:
Emits bursts of impulses in response to meaningful events especially those that produce emotional arousal.
Axons release norepinephrine (NE) throughout the cortex.
Anything that stimulates the (LC) strengthens recent memories and wakefulness.
Silent during sleep.
Brain Mechanisms responsible for arousal (5)
Reticular Formation, Locus Coeruleus, histamine pathway, orexin pathway, basal forebrain
Histamine pathway, orexin (hypocretin) pathway
Histamine Pathway: (4)
Excitatory neurotransmitter used throughout the brain.
Cells active during arousal and alertness.
Antihistamines block this pathway causing drowsiness.
Antihistamines that do not cross the blood brain barrier avoid this side effect.
The orexin or (hypocretin) pathway: (6)
Extend to the basal forebrain .
Stimulate neurons involved with wakefulness.
Orexin is necessary for staying awake.
Drugs that block orexin receptors increase sleep.
Drugs that increase orexin lead to wakefulness and alertness.
Indicated in narcolepsy.
Basal Forebrain (6)
Bas- provides axons for hypo. & cortex
al- Ach & Gaba
Fore- anterior/dorsal to hypo.
brain- sleeping brain (keeps us asleep)
Just anterior and dorsal to the hypothalamus.
Provide axons that go throughout thalamus and cerebral cortex.
Mostly release acetylcholine (ACh), which is excitatory.
Also releases GABA.
GABA prevents spreading of stimulation.
Keeps us asleep.
ACH, Glutamate, inc cortical arousal
NT Locus Coeruleus
Norepinepherin, increases info storage, suppresses REM sleep
NT Excitatory cells
In Basal Forebrain, ACH, excites Thalamus/Forebrain, learning, shift from NREM to REM
NT Inhibitory cells
In Basal Forebrain, GABA, inhibits Thalamus & Cortex
Histamine- increases arousal
Orexin- keeps us awake
NT Dorsal Raphe & Pons
seratonin, interrupts REM sleep
How PET scans work & 2 difficulties
Difficult to execute because it requires injection of a radioactive chemical without awakening the subject.
Further made difficult because any movement of the head during scanning ruins the image.
Image produced by radioactive tracer indicating areas of increased metabolic activity via glucose uptake.
Scans on REM sleep indicate: (4)
Increased activity in Pons and Limbic System.
Decreased activity in primary visual cortex, the motor cortex, and dorsolateral prefrontal cortex.
Increased activity in the parietal and temporal cortex.
Activity in the Pons is regarded as the onset of REM sleep.
Role of the Pons in REM sleep
Pons rides the Pogo!
PGO waves (high amp waves found in REM)=
Cells in the pons also contribute to REM sleep by sending messages to the spinal cord which inhibits motor neurons that control the large muscles of the body.
3 causes of insomnia
Caused by a number of factors including noise, stress, pain medication.
Can also be the result of disorders such as epilepsy, Parkinson’s disease, depression, anxiety or other psychiatric conditions.
Dependence on sleeping pills and shifts in the circadian rhythms can also result in insomnia
Causes/effects of sleep apnea
Consequences include sleepiness during the day, impaired attention, depression, and sometimes heart problems.
Cognitive impairment may result from loss of neurons due to insufficient oxygen levels.
Causes include, genetics, hormones, old age, and deterioration of the brain mechanisms that control breathing and obesity.
REM Behavior Disorder
Usually associated with acting out dreams.
Occurs mostly in the elderly and in older men with brain diseases such as Parkinson’s.
Associated with damage to the pons (inhibit the spinal neurons that control large muscle movements).
3 common sleep disorders
Night terrors are experiences of intense anxiety from which a person awakens screaming in terror.
Usually occurs in NREM sleep.
“Sleep talking” occurs during both REM and NREM sleep.
“Sleepwalking” runs in families, mostly occurs in young children, and occurs mostly in stage 3 or 4 sleep.
Darwin on emotion
Darwin argued that emotions actually served a purpose for humans, in communication and also in aiding their survival.
Darwin argued that emotions evolved via natural selection and therefore have universal cross-cultural counterparts. Darwin also detailed the virtues of experiencing emotions and the parallel experiences that occur in animals (see emotion in animals). This led the way for animal research on emotions and the eventual determination of the neural underpinnings of emotion..
3 components of emotion
1. Cognition (this is a dangerous situation).
2. Feelings (I feel frightened).
3. Actions (fight/run)
Emotions impact on NS
Emotions arouse the autonomic nervous system.
The sympathetic and parasympathetic nervous systems are functionally opposite of one another (i.e. excitation and inhibition), but many situations require the actions of both simultaneously.
(i.e. Nausea = sym. stim. of stomach and parasym. activation of intestines and salivary glands.
1. Drooping upper eyelids
2. Mouth corners slightly down
3. Eyes unfocused
1. Eyelids down/together
2. Eyes Glare
3. Lips narrowed
one sided lip raise
1. Nose wrinkling
2. Upper lip raised
1. Eyebrows raised
2. Eyes wide
3. Mouth open
1. Eyebrows raised and together
2. Eyelids Raised
3. Lower eyelids tightened
4. Lips pulled back horizontally towards ears
2 theories on emotion
The Common Sense View: we first feel an emotion which changes our heart rate, vitals ect.. And prompts other responses.
James-Lange Theory: proposal that an event first provokes autonomic and skeletal responses and that emotion is the perception of those responses
J-L emotional theory predictions (2)
1. Those with weak autonomic and skeletal responses should feel less emotion.
2. Causing or increasing someone's responses should enhance an emotion.
lack of facial control (still felt emotions)
Brain areas associated with emotion (4)
Traditionally, the limbic system has been regarded as critical for emotions.
In particular, the amygdala plays a primary role in the formation of memories associated with emotional events.
Various areas of the cerebral cortex have been indicated in emotions.
Fusiform Face area- recognizing emotions
Function of L Hem in emotion (3)
activity in left, especially frontal and temporal lobes elicits what is known as (The Behavioral Activation System).
Marked by low to moderate autonomic arousal and a tendency to approach.
“Approach” in this context refers to either happiness or anger.
Function of R Hem in emotion (5)
increased activity in the right frontal and temporal lobes is known as the (Behavioral Inhibition System).
Increases attention and arousal and inhibits action.
Stimulates emotions such as fear and disgust.
The right hemisphere seems to be more responsive to emotional stimuli than the left.
Damage to the right temporal cortex causes problems in the ability to identify emotions of others.
Functions of Emotions (3)
1. Adaptive values (fear leads to escape, anger lead to attack, etc.)
2. Allows us to make quick decisions (i.e. gut feeling).
3. Help us make moral decisions
Brain areas involved in moral decisions
Contemplating moral decisions activates the prefrontal cortex, cingulate gyrus, and amygdala
Decisions about right and wrong are seldom worked out rationally, decisions are made emotionally.