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Is the subjective experience of perceiving oneself and one's surroundings
Brain shows no activity and no response to any stimulus
Caused by traumatic brain damage. The brain shows a steady but low level of activity and no response to any stimulus, including potentially painful stimuli. Within a few weeks, someone in a coma usually either dies or begins to recover
Someone starting to emerge from a coma enters the vegetative state
Limited responses-increased heart rate in response to pain
- Studies show that some patients in a vegetative state are sufficiently conscious enough to understand speech and recognize repeated sound patterns
- Brain activity is well below normal, and responsiveness varies between sleeping and waking state
Minimally Conscious State
State in which people have brief periods of purposeful actions and speech comprehensions
Vegetative or minimally conscious state can last for months or even years
A tendency to be unconscious of the left side of the body, the left side of the world, and the left side of objects caused by damage to parts of the right hemisphere
Severe after a right hemisphere stroke
Explanation for impaired consciousness in vegetative state
Activity feeds forward to the prefrontal cortex but the prefrontal cortex fails to feed it back to the originating areas
The alternation between seeing the pattern in the left retina and pattern in the right retina is known as binocular rivalry
(looking through two separate tubes at two different colors)
The increased motor cortex activity prior to the start of a movement
Readiness potential comes before conscious intention
Readiness potential often begins 300 ms or more prior to the reported decision, which occurs 200-300 ms earlier before the movement
Brain starts producing voluntary movements before you are conscious of them
- Way of rehearsing possibilities for future actions
- Conscious thinking modifies your behavior on some future occasion
A rhythm of activity and inactivity lasting about a day
Rising and setting of the sun provides cues to the rhythm, but we generate the rhythm ourselves
- Sleeping, waking
- Urine production
- Temperature (98.9 in late afternoon to 98.1 in the middle of the night)
- Mood- peak of happiness in the late afternoon
A period of discomfort and inefficiency while your internal clock is out of phase with your new surroundings
What rules the internal clock?
The sun, early morning light (the sun rising)
The circadian rhythm of sleep and wakefulness is generated by a tiny structure at the base of the brain known as the suprachiasmatic nucleus
Hormone that is important for both circadian rhythms and many species' annual rhythms of reproduction, hibernation, and so forth
Release of hormone controlled by the suprachiasmatic nucleus
Pineal gland begins releasing melatonin 2 or 3 hours before bedtime
Benefits of sleep
Sleep saves energy (lower body temperature and decreased muscle activity)
Predatory mammals sleep more than prey mammals because they do not need to use as much energy trying to stay alert
Strengthens learning and memory to varying degrees, depending on the type of learning
Fact: When you learn something, your memory improves if you go to sleep within the next three hours (even a nap)
Fact: When people learn a new skill during the day, the same brain areas active during learning become reactivated during sleep that night, only faster.
REM Sleep (paradoxical sleep)
The sleeper's eyes move rapidly back and forth under the closed lids
REM sleep is paradoxical because it is light in some ways and deep in others.
It is light because the brain is active, and the body's heart rate, temperature, and breathing rate fluctuate substantially.
It is deep because the large muscles of the body that control posture and locomotion are deeply relaxed (think sleep paralysis)
REM sleep is not synonymous with dreaming (brain damaged people can have REM sleep but no dreams)
Main characteristic of sleep
The main characteristic of sleep is an increase of inhibitory messages, preventing brain messages from reverberating widely. A spread of messages throughout the brain is central to conscious experience, so blocking those messages inhibits consciousness
EEG combined with simultaneous measure of eye movements
Brain waves in sleep stages increase synchrony among neurons, resulting in decreased brain activity during sleep
Waves in stage 2 sleep that are about 12-14 seconds. Result from an exchange of information between the cerebral cortex and the underlying thalamus.
Important for storing memory
How does a sleeper progress through the stages of sleep?
Sleeper progresses through stages 2, 3, and 4, then gradually back through stages 3 and 2, and then to REM sleep.
Each cycle lasts 90 to 100 minutes on average in healthy, young adults
Not enough sleep for the person to feel rested the next day
Apnea means "no breathing"
People with sleep apnea fail to breathe for a minute or more and then wake up gasping for breath
Experience sudden attacks of sleepiness during the day. They also experience sudden attacks of muscle weakness and paralysis and occasional dreamlike experiences while awake.
- Cause: lack of orexin (neurotransmitter)
- Orexin does not wake people up, but it helps them stay awake
Someone having a lucid dream is aware that they are in a dream
Part of the brain, probably the prefrontal cortex, is more awake than usual during such a dream, and is capable of noticing that the brain is dreaming
Periodic Limb Movement Disorder (Restless Leg Syndrome)
Creepy crawly feelings in the legs at night, accompanied by repetitive leg movements strong enough to awaken the person
Manifest content and latent content
Freud's theory that dreams have a content that appears on the surface-a manifest content, and a latent content- the hidden ideas that the dream experience represents symbolically
Activation-Synthesis Theory of Dreams
Dreams Occur because the cortex takes the haphazard activity that occurs during REM sleep plus whatever stimuli strike the sense organs and does its best to make sense of the activity
(Someone who dreams about peeing may wake up and actually need to pee)
Alternative view of dreaming conditions as opposed to the activation-synthesis theory of dreams
Reduced sensory stimulation, especially in the brain's primary sense areas
Reduced activity in the prefrontal cortex, important for planning and working memory
Loss of voluntary control of thinking
Persisting activity of much of the rest of the cortex, including areas responsible for face recognition and certain aspects of motivation and emotion
Data: Unconscious Decision Making
People tend to make better decisions after a period of unconscious processing than conscious thought
Consciousness can only process 40-60 bits per second, compared to the nervous system, which can process 11,200,000 bits per second
"The Shower Principle"
- Many people find that they come to better conclusions and are more creative after focusing on something else.
- – Driving– Taking a shower– Biking– Drawing, etc.
Stage 1 sleep
- Substantial brain activity, but unsynchronized
- "Drowsy sleep"
- Easy to wake a person up- "I wasn't asleep!"
Stage 2 Sleep
- Heart rate slows
- Body temperature drops
- Preparation for deep sleep
- K-complexes: Large, slow fluctuations in voltage
- Spindles: Bursts of rapid, rhythmic brain waves
Stage 3 and 4 Sleep
- "Deep Sleep" or "Delta Sleep"
- Characterized by deep, slow waves of brain activity called "delta waves".
When most parasomnias occur:
- night terrors
- nocturnal enuresis