consciousness / sleep study guide (copy)

Consciousness

A complex state that is hard to measure and define.

Integrated Information Theory (IIT)

Proposes that consciousness arises from the integration of information in the brain.

Levels of Consciousness

Refers to different states such as awake, dreaming, deep sleep, and drug-induced states.

Global Workspace Theory (GWT)

Changes in consciousness involve alertness and wakefulness.

GWT Examples

awake → clear consciousness

sleeping → fragmented consciousness.

drug-induced → distorted consciousness.

Default Mode Network (DMN)

A network in the brain active during rest, mind-wandering, and creativity.

Prefrontal Cortex (DMN)

Region associated with self-referential thoughts and future planning.

Posterior Cingulate Cortex (DMN)

Involved in memory integration and emotional processing.

Angular Gyrus (DMN)

Linked to language understanding and mental time travel.

Bremer’s Work

Sleep is a behavior generated by the brain, not just an absence of activity.

Lesions To Forebrain

Severing connections between the forebrain and brainstem puts a cat into a permanent sleep-like state.

Memory Consolidation

The process of organizing and solidifying new information during sleep.

Sleep Function #1

Memory consolidation and the transfer of information from short-term to long-term storage.

Songbirds

When sleeping, the brain showed the same neural activity as when they practiced songs while awake.

Hippocampal Activity Spikes During REM

The hippocampus replays the day’s events for storage. More learning = more REM sleep.

Sleep Function #2

Energy conservation during sleep by reducing metabolism.

Slow Wave Sleep Stage 1

Transitional phase. Alpha, theta, beta waves. Jerks, twitching, easily awakened.

Slow Wave Sleep Stage 2

True sleep begins. Theta waves and K complexes. Response to environmental stimuli.

Slow Wave Sleep Stage 3-4

Deep sleep. Mostly delta waves. Hard to awaken. HGH, body repair.

REM Sleep

A sleep stage characterized by muscle atonia, dreaming, and memory consolidation, with beta and theta waves.

Sleep Progression

First 4 hours are slow-wave-dominated, second 4 hours are REM-sleep-dominated.

REM Cycle

Occurs every 90-120 minutes.

Locus Coeruleus (Pons)

A low-level structure linked to norepinephrine and wakefulness.

Raphe Nuclei (Pons)

A low-level structure linked to serotonin and slow-wave sleep.

Gigantocellular Tegmental Field (Pons)

Acetylcholine-based structure linked to REM sleep, originating Ponto-Geniculo Occipital waves.

Preoptic Area Of The Hypothalamus

High-level structure linked to serotonin and releases GABA to inhibit wakefulness.

Posterior Hypothalamus

High-level structure inhibited by the preoptic area that initiates sleep.

Suprachiasmatic Nucleus (SCN)

The brain's center for circadian rhythms and biological clock.

Light Exposure and SCN

Light resets the SCN, aligning sleep/wake cycles with day and night.

Homeostatic Debt

Sleep pressure builds while awake and decreases during sleep.

Glycogen

Builds up during slow-wave sleep and produces ATP, an energy source and reserve.

ATP

Breaks down into adenosine.

Adenosine

A molecule that inhibits wakefulness structures and increases during wakefulness.

Insomnia

A disorder characterized by difficulty falling or staying asleep.

Sleep Apnea

A disorder involving repeated interruptions in breathing during sleep.

Obstructive Apnea

Physical obstruction of the airway.

Central Apnea

Brain fails to send signals to breathe.

Narcolepsy

A disorder characterized by excessive daytime sleepiness and inappropriate REM sleep onset.

Other Narcolepsy Symptoms

cataplexy, paralysis, hallucinations.

Causes Of Narcolepsy

low hypocretin levels, possibly due to autoimmune issues, genetics, or damage to REM/wakefulness areas.

Circadian Rhythm Disorders

When the SCN’s timing does not match societal (night shift) or natural light-dark cycles (jet lag).

Advanced Sleep-Wake Phase Disorder

When the SCN runs shorter than 24 hours, leading to early sleep and waking.

Delayed Sleep-Wake Phase Disorder

When the SCN runs longer than 24 hours, causing late sleep and waking.

Melatonin

A hormone secreted by the pineal gland that promotes sleepiness.

Hypocretin

A substance that promotes wakefulness; low levels are linked to narcolepsy.

Energy Use During Sleep

Sleep lowers metabolism and conserves energy, particularly in species with high metabolic rates.

Brain Development

Critical during sleep, especially in children and adolescents.