Psychology Chapter on Arousal and Sleep

Arousal

• Behavioral arousal is displayed when an organism responds to a stimuli
• Autonomic arousal is demonstrated by changes in bodily functions (heart rate, etc.)
• Cortical arousal is demonstrated by desynchronized, beta wave activity in the brain

Chemicals and Sleep

• Atropine produces EEG activity akin to sleep but the cat/dog will still act normal
• Physostigmine produces EEG activity akin to being alert but the animal behaves as if it is drowsy
• This demonstrates that behavior is not always correlated to autonomic arousal

Hormones and Emotions

• Epinephrine, an adrenal hormone, is related to anger and aggression
• Changes in ANS activity are related to disgust, anger, and fear
• Universal facial expressions are signals of emotional states

Sleep

• Sleep is an overpowering human motive.
• It is adaptive and removes us from situations in which we are least efficient.
• Circadian rhythms operate during sleep.
• Prey animals sleep less than predators.
• Whales and some birds have unihemispheric slow-wave sleep where one half of the brain sleeps
• Sleep decreases with age.

Stages of Sleep

• There are five stages of sleep:
  • Alpha Activity: relaxed wakefulness
  • Stage 1: Irregular low amplitude waves
  • Stage 2: Sleep spindles and K-complexes
  • Stage 3: Slow high-amplitude waves
  • Stage 4: Mix of theta, beta, and alpha waves
• Stage 1 - 4, NREM slow wave sleep. Stage 5 is REM sleep
• REM sleep correlates with dreaming.
• Most REM dreams are bizarre and negative in nature.

Dreams

• 100 minutes per night spent dreaming
• Dreams are not usually emotional, if they are they are usually negative in nature
• Early night dreams are about the day's events (day residues)
• Late night dreams draw on stored memories
• REM sleep changes with age and becomes less stable

Neurocognitive Theory of Dreams

• Dreams rely on maturation and maintenance of forebrain structures
• Continuity Principle: personal concerns during the day enter dreams (day residues)
• Repetition Principle: the same setting, characters, and interactions appear in dreams

Threat Simulation Theory of Dreams

• Dreams allow us to rehearse perceived threats and avoid them through rehearsal in dreams.
• Dreams are usually negative and threatening.
• Aggressive dreams are the most common type
• REM deprivation increases aggression in animals when awake

Physiology of Sleep

• NREM sleep:
  • Blood pressure, heart rate, respiration decline
  • Veins and arteries dilate (vasodilation)
  • Brain waves have high amplitude and are slow
• REM sleep:
  • Blood pressure, heart rate, respiration increase
  • Blood flow to the brain increases
  • Penile erection in males

Brain Stem Structures

• Pons, medulla, RAS are involved in arousal and sleep.
• The RAS receives sensory information from the environment and arouses the thalamus which in turn arouses the cerebral cortex which in turn arouses the RAS.
• When aroused, the RAS sends impulses to the lateral hypothalamus, basal ganglia, and basal forebrain.
• Connections from the basal forebrain activate the cerebral cortex and hippocampus.

Neurotransmitters and Arousal

• Acetylcholine (ACH):
  • Cells in the basal forebrain and pons activate the cerebral cortex.
  • Desynchronized EEG waves occur when stimulated.
  • ACH increases arousal.
• Norepinephrine (NoR-Ep):
  • Cells in the locus coerulus of the pons activate the cerebral cortex, hippocampus, thalamus, cerebellum, pons, medulla.
  • NoR-Ep is high in waking and drops off to zero in REM sleep
• Serotonin:
  • Cells in the raphe nuclei of the pons and medulla connect to the cerebral cortex, hippocampus, thalamus, hypothalamus and basal ganglia.
  • Cells are most active in waking and decrease in sleep.
  • Serotonin influences automatic behaviors. It maintains ongoing behavior and suppresses sensory information that might interrupt those activities.
• Histamine:
  • Cells in the tuberamammillary nucleus of the hypothalamus connect to the cerebral cortex, thalamus, hippocampus, basal ganglia, and basal forebrain.
  • Activity in these cells is high in waking, and low in sleeping.
  • Histamine producing neurons connected to the cortex lead to arousal and attention to environmental stimuli.
  • Anti-histamine drugs block brain histamine receptors which makes one sleepy and less attentive.

Brainstem and NREM Sleep

• Ventrolateral Preoptic Area (VLPO): crucial to delta wave sleep
• Stimulation of VLPO neurons leads to drowsiness
• Animals deprived of sleep and allowed to sleep show an increase in firing of neurons in the VLPO
• Locus Coerulus (LC) and Raphe Nuclei: when active they inhibit REM sleep. REM occurs when the neurons in these regions are inactive.

Brainstem and REM Sleep

• Sub-lateral-dorsal nucleus (SLDn), pre-coeruleus region (PCr), and medial peri-brachial-nucleus (MBn): these cells secrete neurotransmitters, some inhibitory and some excitatory
• Destruction of MBn leads to reduced REM sleep

Adenosine

• Adenosine has an inhibitory effect on neurons that maintain arousal in the pons.
• Two types of receptors for Adenosine: A1 is inhibitory and A2 is excitatory
• Caffeine and theophylline block receptor sites for adenosine.

REM Sleep and Memory

• REM occurs readily after a full day of worry, stress, or intense learning.
• REM deprivation decreases access to emotionally important memories.
• REM connects past memories and present memories related to those past experiences.
• Depression is positively correlated with initial REM onset

Sleep and Age

• Stage 4 (NREM) and REM decline with age
• Infants born prematurely spend 75% of their time in REM. At 3 months, REM drops to 30%.
• REM acts as an internal source of regulation that "sets up" brain organization.

Programming Device

• New information learned during waking changes existing brain organization during REM sleep
• These new inputs are reorganized during REM sleep

Consolidation of Memories

• Dreaming facilitates the transfer of short-term learning to long-term memory.
• REM deprived subjects are more anxious than normal subjects when shown an anxiety provoking film.
• Dreaming during REM allows anxiety provoking material to be incorporated, which leads to habituation, (reduced anxiety response)

Storage of Complex Associative Information

• Recall of complex material is better after isolated REM, as compared to NREM sleep.
• Narcoleptics fall asleep quickly and REM occurs early. This facilitates the consolidation of memory

REM Sleep Syndrome

• This syndrome, caused by brain lesions, interrupts dreaming and memory.
• Increase REM is the brain's way of compensating for these deficits

Sleep and Hippocampus

• Hippocampus neuron firings during learning are re-fired during sleep, which facilitates memory consolidation
• Declarative memories require slow-wave sleep (NREM) to integrate old and new memories

Stress

• Selye defines stress as a non-specific response of the body to any demand made upon it.
• This syndrome represents a set of responses that contain or eliminate the stressor.
• GAS is triggered by both physical and psychological stressors: e.g., loud noises, crowding, anxiety, etc.
• GAS is not always adaptive leading to Diseases of Adaptation: the body and mind are not always able to contain or eliminate the stressor.
• Signal anxiety: a perception of external danger mobilizes the body and mind for defense.
• Internal anxiety arises from the fear of instinctive impulses breaking through the norm.
• Life change, stress, and illness are correlated.
• Meyer investigated the correlation between life change as a stressor and subsequent illness: physical and/or psychological.
• Hinkle found that illness tended to cluster around periods of time in which the social environment or interpersonal relationships made large demands on an individual

Social Readjustment Scale

• This scale correlates the number of events, and the nature of these events, to illness.
• Retrospective studies provided information on this relationship.
• Prospective studies attempt to predict future health changes.
• Popkin found that the larger the number of life changes, the poorer performance in a dog-sled race.
• Immigration studies show that there is no greater incidence of illness for immigrants as compared to the rest of the population.
• Women immigrants experience illness at higher rates compared to men immigrants.

Buffering Effects of Life Changes and Stress

• Personality style and exercise buffer the effects of stress
• People with high stress tend toward negative self-evaluations