Exam #3 Flashcards
Why do we sleep? (4)
Resting muscles.
Decreasing metabolism. (Energy Conservation).
Cellular maintenance, including neurons.
Memory consolidation.
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.
Zeitgeber
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)
- The Suprachiasmatic nucleus (part of hypothalamus)
- Genes that produce certain proteins
- 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
Narcolepsy pattern
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)
- When one falls asleep, they progress through stages 1, 2, 3, and 4 in sequential order.
- After about an hour, the person begins to cycle back through the stages from stage 4 to stages 3 and 2 and than REM.
- The sequence repeats with each cycle lasting approximately 90 minutes.
- Stage 3 and 4 sleep predominate early in the night.
- The length of stages 3 and 4 decrease as the night progresses.
- REM sleep is predominant later in the night.
- Length of the REM stages increases as the night progresses.
- 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
Hypothalamic pathways
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.
