Chapter 10 Psychology - Consciousness

Narcolepsy:

A neurotransmitter called orexin is important for maintaining long periods of wakefulness. People with narcolepsy lose the brain cells that produce orexin and therefore return to a sleeping pattern that resembles that seen in infancy (alternating between brief waking and brief sleeping periods). People with narcolepsy experience sudden attacks of sleepiness during the day. They experience sudden attacks of muscle weakness or paralysis and occasional dreamlike experiences when awake. These symptoms represent intrusions of REM sleep into the waking period. Narcolepsy is a treatable condition. It is treated with a combination of stimulant and antidepressant medications.

Historic conception:

A revelation of unconscious thoughts and motivations. Each dream has manifest and latent content.

Sleep and Dreams Circadian Rhythms

Animal life follows cycles: Hibernation, migration, sleep-wake cycles. Circadian rhythm: A rhythm of activity and inactivity lasting about a day. The cycle of sunrise and sunset provides cues to reset our rhythm. Without those cues, most people generate a sleep-wake rhythm that lasts a little longer than 24 hours, which gradually drifts out of phase with the clock (e.g., people in polar climates).

Night terror:

Awakening screaming and sweating with a racing heart rate, sometimes failing arms and pounding walls. Night terrors occur during stages 3 and 4 of sleep. Dream content, if present at all, is simple and may be only a single image. Comforting the person is futile. The night terror has to run its course. Causes include sleep deprivation, extreme tiredness, sleep schedule disruptions, travel that involves sleep interruptions, fever, sleep- disordered breathing, mood disorders, alcohol over-use. Night terrors are correlated with sleep walking and restless leg syndrome.

Modern conceptions:

Bottom-up processing: 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 this activity (activation-synthesis theory of dreams). Top-down processing: Dreaming is simply a kind of thinking, similar to daydreaming or mind wandering, that occur under conditions of sleep (neurocognitive theory). Neither of these conceptions can be tested in a reliable way. Dreams do appear to reflect interests and worries, but not in the significant and hidden symbolic way that historic researchers hypothesized.

Brain Activity and Consciousness

Brain death: The brain shows no activity and no response to any stimulus. Coma: The brain shows a steady but low level of activity and no response to any stimulus. Vegetative state: Limited responsiveness to stimuli, such as increased heart rate in response to pain. Responsiveness varies between sleeping and waking states, but even in the waking state, brain activity is well below normal. Minimally conscious state: People have brief episodes of purposeful actions and speech comprehension.

Brain Activity and Consciousness

Consciousness involves construction of stimuli that may sometimes have some inaccuracies. | masked by o equals | | o | Our perception of the first two lines is positionally influenced by the masking stimulus and we report the lines, but they are out of alignment as the circles were. Thus, we do not report what we saw. We report a construction of what we saw.

Measuring Consciousness: EEG and MEG

EEG (electroencephalography) and MEG (magnetoencephalography) detectors are placed on the scalp to measure rapid changes in the brain's electrical or magnetic activity. These techniques identify the approximate location of activity, with timing of the activity that is accurate to the millisecond. For some research purposes, approximate locations are sufficient.

Stages of Sleep

Electroencephalography (EEG) measures and amplifies tiny electrical changes on the scalp that reflect patterns of brain activity. Sleep researchers combine EEG measures with simultaneous measures of eye movements to produce a polysomnograph.

Circadian Rhythms

Human circadian rhythms control sleep and wake, but they also control other functions: Hunger, thirst, urine production, blood pressure, alertness, and body temperature. Genes have an influence on circadian rhythms. 23-hour cycle: People enjoy going to bed early and awakening early. 25-hour cycle: People enjoy going to bed late and sleeping late. Reduced need for sleep cycle: Some people need less than 8 hours of sleep.

Binocular rivalry:

If you look through tubes at stimuli, with one eye focused on one stimulus and the other eye focused on a different stimulus, your eyes eventually alternate back and forth between the perception in one eye versus the other eye. This phenomenon is known as binocular rivalry.

Flash suppression:

Imagine a yellow dot surrounded by a circle of blue dots. If the blue dots rotate, or if other dots flash onto the computer screen, you lose site of the central yellow dot. This is known as flash suppression.

Measuring Consciousness

In the foregoing procedures, an observer is conscious of the stimulus under one condition and not under the other, but the initial processing is the same. The retina responds to the visual stimulus equally in both cases, and sends equivalent messages to the cortex. For about the first 200 ms, the response in the visual cortex is about the same for stimuli destined for consciousness or unconsciousness. For about the next second after that, the responses diverge. Not conscious of the stimulus: The response remains weak and mostly localized to the primary visual cortex: Conscious of the stimulus: The activation spreads quickly from the visual cortex to many brain areas and then rebounds back from the prefrontal cortex to the primary visual cortex, magnifying and prolonging the response there. This is known as an echo effect.

Nightmare:

Intensely unpleasant dream.

The Purpose of Consciousness

Is consciousness superfluous? Does consciousness serve a purpose? In a universe of matter and energy, why do we have consciousness? If you can answer these questions, you should wait by the phone for the Nobel Prize.

Circadian Rhythms

It is possible to ease the transition when you need to adjust your circadian rhythms. Always transfer from an earlier shift to a later shift. Provide bright lights on the night shift. Shift schedules every 2+ weeks, not weekly. It takes at least 6 days to adjust, even with the above procedures.

Insomnia:

Lack of sleep, insufficient sleep for the person to feel rested the next day. Causes: Noise, worrying, indigestion, uncomfortable room temperature, over-use of alcohol or caffeine, physical and mental illnesses, irregular sleep-wake cycle, insufficient daytime sunlight exposure, physical exercise right before bedtime, inadequate exposure to sunlight, use of television or computer right before bedtime.

Circadian Rhythms

Light resets the internal clock, causing you to wake up more or less in synchrony with sunlight. Unlike most retinal cells that respond in an on-off way to light and darkness, a special set of ganglion cells on the nasal side of the retina respond to the average amount of bright light over a period of time and send their output to the SCN. These ganglion cells respond mainly to short-wavelength light. Short wavelength cells are emitted by computers and television, which explains why people who use these devices late in the evening often have trouble sleeping.

Measuring Consciousness

Masking is a method of hiding a stimulus from consciousness even though it is perceived for the same amount of time as an un-masked stimulus. A word appears on a screen for a fraction of a second (29 milliseconds). It is preceded and/or followed by an interfering stimulus. Masking: The interfering stimulus precedes the stimulus. Backward Masking: The interfering stimulus follows the stimulus.

Brain Activity and Consciousness

Measurable consciousness appears to be an all-or- nothing phenomenon. People do not report partial consciousness of a stimulus, although they do correctly guess slightly more than average when presented with weak stimuli. Brain activity is either robust or weak. It is never intermediate.

Sleep apnea:

Most people have occasional brief periods without breathing while sleeping. People with sleep apnea fail to breath for a minute or more and then wake up gasping for breath. They may lie in bed for 8-10 hours but sleep less than half that time. Risk factors: Excess weight, neck circumference, alcohol over-use, over-use of sedatives or tranquilizers, smoking, nasal congestion, aging. Males are twice as likely as females to have sleep apnea. The risk of sleep apnea increases in women after menopause.

Consciousness and Action

On certain tasks, as measured by brain activation, readiness to move takes place before reported conscious awareness that the individual is about to move. Is the delay due to the fact that movement readiness precedes conscious awareness? Is the delay due to the discrepancy between a decision and the report of a decision? Researchers can only measure movements in response to decision making. It is difficult to design a study that records spontaneous movement that was not a function of a decision. What is happening in the brain when we engage in spontaneous movements? Do we engage in spontaneous movements or is there always a low-level decision process? Instructions lead to fairly rapid motor movements. Spontaneous movements tend to be gradual. The basil ganglia is activated by spontaneous but gradual movements.

Measuring Consciousness

Philosophers and psychologists ask the question of why consciousness exists at all. There is a long history of speculation as to what constitutes consciousness. Cogito ergo sum: I think, therefore I am. —René Descartes Descartes asserted that the very act of doubting one's own existence served—at minimum—as proof of the reality of one's own mind; there must be a thinking entity—in this case the self—for there to be a thought.

Periodic limb movement disorder (restless leg syndrome):

Prolonged uncomfortable sensations in legs (and sometimes the arms), accompanied by irresistible and repetitive leg movements strong enough to awaken the person, especially during the first half of the night.

Measuring Consciousness

Psychologist postpone questions of consciousness that are the most difficult answer. They focus on limited and answerable questions: How does conscious-of-a-stimulus brain activity differ from not- conscious-of-a-stimulus brain activity? As you direct attention from one sensation to another, you become aware of sensations that have been present but unconscious or not fully conscious until that moment. Can we measure that shifting of conscious awareness?

Stages of Sleep

Rapid eye movement (REM) sleep: The eyes move rapidly back and forth under the closed lids. The brain is active and the body's heart rate, breathing rate, and temperature fluctuate substantially. The large muscles of the body that control posture and locomotion are deeply relaxed. People who are awakened during REM sleep report dreams 89-90% of the time. People who are awakened during non-REM sleep report dreams 50-60% of the time. REM sleep is important. If you are deprived of REM sleep, you may experience anxiety, irritability, hallucinations, difficulty concentrating and increased appetite.

Circadian Rhythms

Shifting sleep schedules cause reductions in alertness, cognitive efficiency, fatigue, and discomfort. Your internal clock is out of phase with your surroundings. Jet lag. Rotating shift-work schedules. Daylight Savings Time.

Circadian Rhythms

Sleep deprivation produces a pattern of progressive deterioration, superimposed on the normal circadian cycle of rising and falling of body temperature and alertness. 1st night: sleepy from 2:00 a.m.-6:00 a.m., then rebound of alertness. 2nd night, the cycle continues but cognitive clarity weakens. 3rd night, as above. A week or so: Vulnerability to symptoms of physical and mental illness, lapses of attention, lapses of ethical behavior, dangerousness while driving, declining capacity for learning and memory.

Sleep

Sleep saves energy. Sleep evolved to help us save energy. Sleep consolidates learning and memory. When people learn a new motor task, the brain areas active during learning becomes reactivated during sleep. The amount of activity in those areas during sleep predicts the amount of improvement the next day. Wakefulness and sleep play complementary roles in learning. Learning strengthens the appropriate synapses during wakefulness and weakens other synapses during sleep.

Sleep talking:

Sleep talking is a common experience. It ranges from on occasional word to a full paragraph. It is most common during stage 2 sleep but it may occur in all stages.

Sleep walking:

Sleep walking is hereditary. It occurs mainly during stage 4 sleep. Sleep walking consists of clumsy and apparently purposeless movements, although movements can sometimes be organized and serve a function. Sleep can be localized to one brain area more than another. Sleep walking occurs when the motor cortex and a few other areas are active while most of the brain remains asleep.

Circadian Rhythms

Sleep-wake is generated within the brain by a tiny structure known as the suprachiasmatic nucleus. If damaged, the body's activity cycles become erratic. If cells from the SCN are kept alive outside the body, they generate a 24- hour rhythm on their own. Cells in other brain regions also produce daily rhythms, but the SCN is the body's main clock.

Brain Activity and Consciousness

The brain notices something meaningful or important before you are fully conscious of it. In both flash suppression and binocular rivalry experiments, researchers manipulate presentations of data so that the individual becomes conscious of a stimulus. They then introduce emotional faces versus neutral faces or words in one's native language versus a non-native language. The brain responds to emotional faces more than neutral faces, and to known language more than non-familiar language. The brain responds before the individual reports conscious awareness.

Consciousness:

The subjective experience of perceiving oneself and one's surroundings. Research definition of consciousness: If a person reports being conscious or aware of one stimulus and not of another, then the person was conscious of the first one and not the second.

Circadian Rhythms

The suprachiasmatic nucleus exerts its control partly by regulating the pineal gland's secretion of the hormone melatonin, which is important for both circadian rhythms and many species' annual rhythms of reproduction and hibernation.

Circadian Rhythms

There are variations in sleep-wake cycles across the age span. Young people are more likely to be "evening people." Older people are more likely to be "morning people." This phenomenon is observed in both human and non- human animals.

Brain Activity and Consciousness

Vegetative and minimally conscious states can last four months to years. It is possible to elicit brain activation in response to instructions to imagine playing tennis or imagine walking through the house. Activation is seen in brain areas responsible for spatial navigation. Some individuals in these states are able to direct their attention to pictures (face versus house) and to respond to yes/no questions, as demonstrated by activity in brain regions of relevance.

Sleep spindles:

Waves of activity (12 to 14 per second) that result from an exchange of information between the cerebral cortex and the underlying thalamus. Sleep spindles are important for storing memory. The improvement of memory that often occurs after sleep depends on the amount of sleep spindles.

Brain Activity and Consciousness

When you become conscious of a stimulus, it produces more brain activity and more spread to across the brain. It also produces more inhibition of other competing stimuli and brain activity. In binocular rivalry, the brain responds to a certain degree to the unconscious stimuli. The brain shows a robust response to the conscious stimuli.

Measuring Consciousness: fMRI

fMRI (functional magnetic resonance imaging) identifies the location of activity with much greater precision but with less timing precision.