Study Notes on Consciousness

Chapter 5: Consciousness

The Nature of Consciousness

  • Consciousness: Definition and Characteristics

    • Subjective and Private: Each individual's experience of consciousness is unique and cannot be directly shared with others.

    • Dynamic: Consciousness is not static; it changes continually in response to internal and external stimuli.

    • Self-Reflective: Individuals are aware of their own thoughts and feelings, allowing for introspection and self-evaluation.

The Electroencephalograph (EEG)

  • Definition: A tool used to measure electrical activity in the brain, particularly useful for studying states of consciousness.

  • Frequency Bands: Different brainwave frequencies identified by EEG include:

    • Beta Waves: Associated with active, alert states, often seen during problem-solving or focused activity.

    • Alpha Waves: Present during relaxed wakefulness; indicate a state of calm, alert rest.

    • Theta Waves: Associated with light sleep or deep relaxation, often seen in creative states.

    • Delta Waves: Indicate deep sleep, essential for restorative processes in the body and brain.

Sleep Stages

  • Stages of Sleep: Defined by EEG patterns and psychological characteristics.

    • Awake: Conscious state with beta and alpha activity.

    • Stage 1: Light sleep marked by theta waves.

    • Stage 2: Characterized by the presence of sleep spindles and K-complexes in the EEG; marks the transition to deeper sleep.

    • Stage 3: Deep sleep with delta waves predominant.

    • Stage 4: Also a deep sleep stage with significant delta wave activity, essential for physical recovery.

    • REM Sleep: Associated with vivid dreaming; occurs cyclically and reflects heightened brain activity similar to wakefulness.

Circadian Rhythms

  • Definition: Biological rhythms that follow a roughly 24-hour cycle, influencing physiological functions such as sleep and wakefulness.

  • Core Body Temperature: Fluctuates throughout the day, often correlating with sleep/wake cycles; normal values range between 96.8°F and 100.4°F.

Sleep Disorders

  • Dyssomnias: Disorders that affect the amount, timing, and quality of sleep.

    • Insomnia:

    • Symptoms: Difficulty initiating sleep or maintaining sleep, causing distress or impaired daytime functioning.

    • Prevalence: Affects approximately 1/3 of the population annually; among children, prevalence ranges from 25-40%.

    • Nightmares:

    • Definition: Disturbing dreams leading to awakenings, primarily in REM sleep, characterized by the ability to vividly recall the dream.

    • Night/Sleep Terror:

    • Definition: Episodes of abrupt awakening from NREM sleep, often marked by intense fear and autonomic arousal signs.

    • Sleep Walking:

    • Definition: Repeated episodes of getting out of bed during NREM sleep; common in children (15% have at least one episode).

Drug Dependence and Abuse

  • Drug Dependence:

    • Definition: A maladaptive pattern of substance use leading to clinically significant impairment or distress.

    • Key Features:

    • Tolerance: Need for increased amounts to achieve the desired effect.

    • Withdrawal: Physiological and cognitive responses to the absence of the substance.

    • Substance usage is often prolonged and compulsive.

  • Drug Abuse:

    • Definition: Continued use of a substance despite significant problems related to use, including failure to fulfill obligations and hazardous situations.

Abused Drugs and Their Effects

  • Narcotics:

    • Definition: A category of drugs that reduce pain, induce sleep, and lead to a euphoric state.

    • Examples: Opiates such as heroin and morphine.

    • Withdrawal Symptoms:

    • Includes agitation, anxiety, muscle aches, insomnia, abdominal cramping, nausea, and vomiting.

  • Sedatives:

    • Definition: Substances that decrease CNS activity and reduce arousal levels, inducing relaxation.

    • Examples: Alcohol and barbiturates.

    • Withdrawal Symptoms: Sweating, increased heart rate, hand tremors, insomnia, nausea, vomiting, and anxiety.

  • Stimulants:

    • Definition: Substances that increase physical arousal and mental alertness.

    • Examples: Amphetamines, cocaine, nicotine, caffeine.

    • Withdrawal Symptoms: Fatigue, increased appetite, vivid unpleasant dreams, insomnia, psychomotor retardation, or agitation in the case of cocaine; irritability and anxiety with nicotine cessation.

  • Cannabis:

    • Definition: A drug that alters mental and emotional perceptions and distorts sensory perceptions.

    • Primary Ingredient: Tetrahydrocannabinol (THC).

    • Effects Duration: Lasts approximately 2-3 hours and includes increased heart rate, appetite, and feelings of well-being.