Chapter 5 Variations in Consciousness

Awareness of Internal and External Stimuli Levels of awareness

James – stream of consciousnessFreud – unconsciousSleep/dreaming

Consciousness: Personal Awareness

EEG – monitoring of brain electrical activity Brain-waves

Amplitude (height) Frequency (cycles per second)

Beta (13-24 cps)Alpha (8-12 cps)Theta (4-7 cps)Delta (<4cps)

The Electroencephalograph: A Physiological Index of Consciousness

Figure 5.1The correlation between mental states and electrical activity in the brain. As discussed in Chapter 2, correlations alone do not establish causation. For example, there are strong correlations between drowsiness and a particular pattern of cortical activity, as reflected by EEG brain waves. But does drowsiness cause a change in cortical activity, or do changes in cortical activity cause drowsiness? Or does some third variable account for the changes in both?

Circadian Rhythms – 24 hr biological cycles Regulation of sleep/other body functions Physiological pathway of the biological clock:

Light levels -> retina -> suprachiasmatic nucleus of hypothalamus ->

pineal gland -> secretion of melatonin

Biological Rhythms and Sleep

Figure 5.2Examples of circadian rhythms. These graphs show how alertness, core body temperature, and the secretion of growth hormone typically fluctuate in a 24-hour rhythm. Note how alertness tends to diminish with declining body temperature.

Figure 5.3Circadian rhythms and jet lag. Jet lag can be assessed in a variety of ways. In a study of people flying between Detroit and London, which requires a 5-hour time shift, Nicholson et al. (1986) looked at the time it took travelers to fall asleep the night before their trip and the next five nights after their flight. As you can see, subjects who flew eastward had increased difficulty falling asleep, whereas subjects who flew westward showed no evidence of jet lag on this measure. The data are consistent with other findings that air travelers generally adjust more slowly after flying east (which shortens their day) than after flying west (which lengthens it).

Figure 5.3Changes in sleep periods of a subject isolated from the day-night cycle. The drift of the sleep periods to the right is characteristic of studies in which subjects are deprived of information about day and night. Subjects typically drift toward a 25 hour day, retiring later and later with each day spent in isolation. When subjects are re-exposed to light-cycle cues, they quickly return to a 24-hour rhythm.

Instruments: Electroencephalograph – brain electrical activity Electromyograph - muscle activity Electrooculograph – eye movements

Other bodily functions also observed

Sleep/Waking Research

Sleep Stages: Cycling Through Sleep

Stage 1: brief, transitional (1-7 minutes) alpha -> theta hypnic jerks

Stage 2: sleep spindles (10-25 minutes) Stages 3 & 4 : slow-wave sleep (30 minutes) Stage 5: REM, eeg similar to awake, vivid dreaming (initially

a few minutes, progressively longer as cycle through the stages)

Figure 5.4EEG patterns in sleep and wakefulness. Characteristic brain waves vary depending on one’s state of consciousness. Generally, as people move from an awake state through deeper stages of sleep, their brain waves decrease in frequency (cycles per second) and increase in amplitude (height). However, brain waves during REM sleep resemble “wide-awake” brain waves.

Figure 5.5An overview of the cycle of sleep. The white line charts how a typical, healthy, young adult moves through the various stages of sleep during the course of a night. This diagram also shows how dreams and rapid eye movements tend to coincide with REM sleep, whereas posture changes occur in between REM periods (because the body is nearly paralyzed during REM sleep). Notice how the person cycles into REM four times, as descents into NREM sleep get shallower and REM periods get longer. Thus, slow-wave sleep is prominent early in the night, while REM and stage 2 sleep dominate the second half of a night’s sleep. Although these patterns are typical, keep in mind that sleep patterns vary from one person to another and that they change with age.

Figure 5.5 cont.

Figure 5.6Changes in sleep patterns over the life span. Both the total amount of sleep per night and the portion of sleep that is REM sleep change with age. Sleep patterns change most dramatically during infancy, with total sleep time and amount of REM sleep declining sharply in the first two years of life. After a noticeable drop in the average amount of sleep in adolescence, sleep patterns remain relatively stable, although total sleep and slow-wave sleep continue to decline gradually with age. (Adapted from Roffwarg, Muzio, & Dement, 1966; revised by authors since publication)

Brain Structures: Ascending reticular activating system Pons, medulla, thalamus, hypothalamus, limbic

system Neurotransmitters:

Acetylcholine and serotonin Also norepinephrine, dopamine, and GABA

The Neural Bases of Sleep

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Figure 5.7The ascending reticular activating system (ARAS). A number of brain areas and structures interact to regulate sleep and waking. Particularly important is the ARAS (represented by the white arrows), which conveys neural stimulation to many areas of the cortex.

Hypothesis 1:

Sleep evolved to conserve organisms’ energy Hypothesis 2:

Immobilization during sleep is adaptive because it reduces danger

Hypothesis 3:

Sleep helps animals to restore energy and other bodily resources

Why Do We Sleep?

Complete deprivation

3 or 4 days max Partial deprivation or sleep restriction

impaired attention, reaction time, coordination, and decision accidents: Chernobyl, Exxon Valdez

Selective deprivation

REM and slow-wave sleep: rebound effect

Sleep Deprivation

Figure 5.8Effect of sleep deprivation on cognitive performance. Experimental subjects in the Pilcher and Walters (1997) study underwent 24 hours of sleep deprivation prior to taking the Watson-Glaser Critical Thinking Appraisal. As you can see, their performance on this cognitive test was clearly inferior to that of the control subjects, who had not experienced sleep deprivation.

Insomnia – difficulty falling or staying asleep Narcolepsy – falling asleep uncontrollably Sleep Apnea – reflexive gasping for air that awakens Nightmares – anxiety arousing dreams - REM Night Terrors – intense arousal and panic - NREM Somnambulism – sleepwalking

Sleep Problems

Figure 5.10The vicious circle of dependence on sleeping pills. Because of the body’s ability to develop tolerance to drugs, using sedatives routinely to “cure” insomnia can lead to a vicious circle of escalating dependency as larger and larger doses of the sedative are needed to produce the same effect.

Figure 5.20Variation in sleep needs. Based on data from a variety of sources, Webb (1992b) estimates that average sleep length among young adults is distributed normally, as shown here. Although most young adults sleep an average of 6.5 to 8.5 hours per night, some people need less and some people need more sleep.

Figure 5.22The vicious circle of anxiety and sleep difficulty. Anxiety about sleep difficulties leads to poorer sleep, which increases anxiety further, which in turn leads to even greater difficulties in sleeping.

Figure 5.23Thoughts and emotions associated with insomnia. This graph depicts the percentage of insomniacs and control subjects reporting various presleep feelings and thoughts. Insomniacs’ tendency to ruminate about their problems contributes to their sleep difficulties. (Based on data from Kales et al., 1984)

Figure 5.11Sleep problems and the cycle of sleep. Different sleep problems tend to occur at different points in the sleep cycle. Whereas sleepwalking and night terrors are associated with slow-wave sleep, nightmares are associated with the heightened dream activity of REM sleep.

Dreams – mental experiences during sleep Content usually familiar Common themes Waking life spillover – day residue

Western vs. Non-Western interpretations

Dreams and Dreaming: Content and Significance

Figure 5.12Three theories of dreaming. Dreams can be explained in a variety of ways. Freud stressed the wish-fulfilling function of dreams. Cartwright emphasizes the problem-solving function of dreams. Hobson and McCarley assert that dreams are merely a by-product of periodic neural activation. All three theories are rather speculative and have their critics.

Hypnosis = a systematic procedure that increases suggestibility

Hypnotic susceptibility: individual differences Effects produced through hypnosis:

Anesthesia Sensory distortions and hallucinations Disinhibition Posthypnotic suggestions and amnesia

Hypnosis: Altered State of Consciousness or Role Playing?

Meditation = practices that train attention to heighten awareness and bring mental processes under greater voluntary control

Yoga, Zen, transcendental meditation (TM) Potential physiological benefits

Similar to effective relaxation procedures

Meditation

6 categories of psychoactive drugs Narcotics (opiates) – pain relieving Sedatives – sleep inducing Stimulants – increase CNS activity Hallucinogens – distort sensory and perceptual experience Cannabis – produce mild, relaxed euphoria Alcohol – produces relaxed euphoria, decreases in inhibitions

Principal Abused Drugs and Their Effects

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Figure 5.16Amphetamines and neurotransmitters. Like other psychoactive drugs, amphetamines alter neurotransmitter activity at specific synapses. Depicted here are two ways (there may be more) in which amphetamines appear to increase dopamine (DA) activity at DA synapses and norepinephrine (NE) activity at NE synapses.

Figure 5.17The “crash” after use of cocaine or amphetamines. Stimulant drugs induce an emotional high that is often followed by an emotional letdown called a “crash.” Larger doses of the drugs tend to precipitate bigger crashes. As the text explains, the crash is attributable to the depletion of certain neurotransmitters.