Lecture Slides - States of Consciousness (2)

What Is Consciousness?

Definition: Consciousness is defined as the awareness of internal and external stimuli, which encompasses a wide array of experiences including thoughts, emotions, bodily sensations (such as hunger and pain), and visual inputs. It serves as an essential aspect of our cognitive ability, enabling us to navigate and interpret our environment.

Subjective Experience: Consciousness embodies one's moment-by-moment subjective experience. This means that each individual’s conscious awareness is closely linked to their brain activity, which varies from person to person. The nature of these experiences leads to profound philosophical inquiries, including the key question: Do we all perceive colors, such as red, in the same way? This highlights the unique, personal nature of consciousness and the challenges in understanding the subjective experiences of others.

Brain Activity and Consciousness

Mechanism: Consciousness arises from complex interactions within the brain, heavily influenced by neural connectivity and chemical signaling. Various brain regions contribute to the formation of conscious experience.

Visual Processing: This involves several key areas of the brain:

• Visual Cortex: This area is crucial for processing visual information and interpreting what we see.

• Midbrain and Parietal Cortex: These regions play significant roles in the distribution of visual inputs and coordinating visual attention.

Blindsight: A fascinating phenomenon that illustrates the complexities of consciousness, blindsight occurs when individuals can respond to visual stimuli without consciously seeing them, showcasing the distinction between awareness and perception.

Biological Rhythms & Sleep

Circadian Rhythm: A critical biological rhythm that occurs roughly every 24 hours, influencing numerous bodily functions. Controlled by:

• Hypothalamus: Acts as the body’s biological clock, regulating the sleep-wake cycle among other functions.

• Suprachiasmatic Nucleus (SCN): This cluster of cells guides the body's circadian rhythms by responding to light cues from the environment.

Disruptions: Circadian rhythms can be adversely affected by several factors:

• Jet Lag: A condition resulting from conflicts between internal circadian cycles and external sleep patterns due to long-distance travel.

• Rotating Shift Work: Constantly changing work schedules can disrupt natural biological patterns, posing a challenge to maintaining regular sleep habits.

Characteristics of Sleep

Definition of Sleep: Sleep is defined as an altered state of consciousness characterized by specific physiological changes, making it both homeostatic and rhythmic in nature.

Characteristics: Notable features of sleep include:

• Low Levels of Physical Activity: Muscular tone is significantly reduced.

• Reduced Sensory Awareness: The brain's responsiveness to external stimuli diminishes during sleep.

Stages of Sleep

Hypnogram: A diagram that shows the various stages of sleep throughout a sleep period.

Stages of Sleep: Sleep is categorized into several stages:

• Stage 1: Light sleep characterized by the presence of alpha waves.

• Stage 2: Marked by theta waves, accompanied by sleep spindles and K-complexes, indicative of deeper relaxation.

• Stages 3 & 4: Consist of delta (slow-wave) sleep, which is essential for restorative processes.

Brain Activity Changes: These changes can be observed through EEG, showing distinct patterns across different sleep stages.

Sleep Requirements by Age

Nightly Sleep Needs: The following are recommended sleep durations based on age:

• 0–3 months: 12–18 hours.

• 3 months–1 year: 14–15 hours.

• 1–3 years: 12–14 hours.

• 3–5 years: 11–13 hours.

• 5–10 years: 10–11 hours.

• 10–18 years: 8–10 hours.

• 18 and older: 7–9 hours.

Sleep Debt: Sleep debt accumulates when an individual fails to achieve adequate sleep, leading to decreased alertness, cognitive performance, and overall efficiency.

Sleep Rebound: Individuals who are sleep-deprived tend to fall asleep quickly and may experience longer durations of deep sleep when given the opportunity to rest properly.

Consequences of Sleep Deprivation

Cognitive Impairments: Sleep deprivation can lead to significant cognitive issues, including memory loss and reduced mental efficiency, affecting day-to-day functioning.

Health Risks: Chronic sleep deprivation is associated with severe health risks, including an increased likelihood of developing heart disease, obesity, and type 2 diabetes.

Benefits of Sleep

Physical Health: Sleep plays a crucial role in maintaining a healthy weight and regulating stress levels, thus contributing to overall physical well-being.

Cognitive Function: Adequate sleep is essential for peak cognitive performance; lack of sleep disrupts memory formation and cognitive processing.

Adaptive Function: Sleep restores resources expended during the day and serves as an evolutionary response to mitigate predation risks during vulnerable hours.

Dreams and Sleep Disorders

Nature of Dreams: Dreams represent an altered state of consciousness, often marked by experiences that can feel vividly real. These occurrences can be confusing and are often influenced by waking life.

REM vs. Non-REM Dreams:

• REM Dreams: Characterized by bizarre, emotionally intense experiences involving vivid visual and auditory hallucinations.

• Non-REM Dreams: Typically more mundane and less vivid in comparison.

Parasomnias: Unwanted behaviors occurring during sleep include:

• Sleepwalking (Somnambulism).

• Restless Leg Syndrome.

• Night Terrors.

REM Sleep Behavior Disorder: This condition involves individuals acting out their dreams due to a lack of the usual paralysis during REM sleep, presenting potential dangers.

Common Sleep Disorders

Insomnia: A prevalent condition where individuals find it challenging to fall asleep or stay asleep, leading to impaired functioning during the day.

Sleep Apnea: Characterized by temporary interruptions in breathing during sleep, which can lead to fragmented sleep and reduced oxygen supply to the body; includes obstructive and central types.

Narcolepsy: This disorder is marked by overwhelming daytime drowsiness and sudden sleep attacks, often at inappropriate times.

Understanding Drug Effects on Consciousness

Tolerance: Refers to the phenomenon where individuals require increasing amounts of a drug to achieve the same effects, indicating an adaptation by the brain over time.

Withdrawal: A set of negative symptoms experienced during the abstinence from a drug, often leading to cravings and discomfort.

Substance Use Disorders: Characterized by compulsive drug use despite harmful consequences, reflecting both psychological and physical addiction.

Psychoactive Substances

Alteration of Brain Chemistry: Psychoactive drugs can significantly change brain functioning and influence user behavior and experiences.

Categories of Psychoactive Substances:

• Stimulants: Increase mental and behavioral activity (e.g., caffeine, cocaine).

• Depressants: Decrease mental and behavioral activity (e.g., alcohol, opioids).

• Hallucinogens: Cause perceptual changes, altering the experience of reality (e.g., LSD, PCP).

Effects of Depressants

Examples: Drugs such as alcohol, barbiturates, and benzodiazepines affect GABA receptors to reduce neuronal activity.

Alcohol's Effects:

• Low doses can lead to relaxation and mild euphoria.

• High doses can result in motor incoordination, slowed reaction times, and significant cognitive impairment.

Opioids and Their Effects

Medically Used: Opioids are powerful pain relievers (analgesics) used in clinical settings, including substances like heroin, morphine, and methadone.

Endogenous Opioid System: This is the body’s natural pain control system that modulates pain and well-being through the release of endorphins.

Stimulants and Their Functions

Types: Common stimulants include cocaine and amphetamines, both known for their potent effects on enhancing alertness.

Mechanism: Stimulants typically increase dopamine levels by blocking reuptake and enhancing the release of this neurotransmitter in the brain.

Cocaine: Derived from coca leaves, cocaine significantly impacts mood and energy levels, often leading to addictive behavior.

Caffeine: A widely consumed mild stimulant often thought of as safe, yet overuse can lead to negative health effects.

Hallucinogens and Cannabis

Definition: Hallucinogens are substances that induce sensory and perceptual changes, leading to altered reality experiences (e.g., LSD, psilocybin).

Cannabis: Contains THC and CBD compounds, known for producing relaxation and altered perceptions. Its legal status has evolved, with adult use being legal in many jurisdictions as of 2023.