Knowt
Note
Studied by 26 people
BCS 110 Exam III Review
BCS 110 Exam 3 Review Session
Sleeping and Circadian Rhythms
Stages of Sleep
Awake
Low voltage, High frequency
Brain not in sync; Beta and Gamma waves
Pre-sleep
Brain begins to sync; intermittent Alpha waves
Stage 1 (Light Sleep)
Easy to wake; Theta waves
Stage 2
Sleep spindles: high-frequency bursts from Thalamus; K-complexes
Surges when Thalamus decides to wake or maintain sleep
Mainly Theta waves
Stage 3
Occasional Delta waves
Stage 4 (Deep Sleep/REM)
Predominantly Delta waves; dreaming occurs
Loss of muscle tone (paralysis)
Increased Beta and Gamma waves, resembling awake state
Emergent Stage 1
Course of Sleep
Sleep cycles occur approximately every 90 minutes: 1 -> 4 -> Emergent 1 -> 4, repeat
Deep sleep occurs within the first 1.5-3 hours of sleep
Sleepwalking occurs in stages 3 and 4, where muscles are paralyzed
Total awareness near the end of sleep; typically mistaken for deep sleep
Important to remember the sleep stage pattern!
Theories of Dreaming
Emergent Stage 1 Sleep
Everyone dreams; however, recollection varies
Subconscious Theory
Freudian theory: dreams reenact life events; largely disbelieved now
Activation-Synthesis Theory
Brain creates narrative based on random sensory inputs occurring during sleep
DLPFC contributes to story creation from received stimuli
Theories of Sleep
Recuperation Theory
Helps restore homeostatic balance (sodium reduction and nutrient restoration)
Evidence of Recuperation
Dolphins have uni-hemispheric sleep, indicating recuperation need
Adaptation Theory
Argues no homeostatic deficit; sleep has evolved as a protective mechanism
Sleep Deprivation
Sleep deprivation is personal; you can't 'bank' sleep
Long wakefulness can induce physiological and psychological disturbances, but varies
Physiological Evidence: reduced immunity, increased BP, lower body temp
Mood impacts: bad mood, lack of creativity, sleepiness; worsens with deep sleep deprivation
Potential positive role of REM: aids in memory processing and waking readiness
Logical and critical thinking often remain intact during sleep deprivation
Circadian Rhythms
Cycle approximately 24 hours, driven by zeitgebers (environmental cues)
Altered Cycles:
Free-running Cycle: Internal clock without environmental cues (~25 hours)
Jet Lag: shift in sleep caused by changes in zeitgebers (east vs. west travel)
Suprachiasmatic Nucleus (SCN)
Main circadian clock; responds to light input directly from retina
If SCN is removed, sleep cycles can shift dramatically
Transplanting SCN results in transplanting sleep cycles
Sleep-Wake Areas
Four key areas:
VLPO (Ventrolateral Preoptic Area): Initiates sleep
LHA (Lateral Hypothalamus): Initiates wakefulness
Rostral and Caudal nuclei: Regulate wake/sleep transitions
Sleep regulated by two neural processes: recuperation (need) and adaptation (urge)
Sleep Cycle: Wake
LC releases norepinephrine to LHA and the brain
LHA sends orexin back to support wakefulness
LC sends GABA to suppress sleep centers
SCN also sends GABA to suppress VLPO
Sleep Cycle: Sleep
Adenosine levels rise throughout the day, pushing need for sleep
SCN quiets at night as the pineal gland releases melatonin
VLPO activates, inhibiting LC, leading to REM sleep activation
LC disappears, REM activates; cycle continues
Sleep Drugs
Hypnotics: Activate GABA to inhibit wake centers; potential addiction
Antihypnotics: Reduce sleep time; stimulate sympathetic system
Chronobiotics: Alter circadian rhythms, melatonin supplements used for travel
Sleep Disorders
Insomnia: Difficulty falling or staying asleep
Sleep Apnea: Interrupted breathing during sleep
Hypersomnia / Narcolepsy: Excessive sleepiness during the day; often linked to deficiencies in orexin or norepinephrine
Hypothalamic Nuclei
SCN: Circadian clock
VLPO: Sleep regulation
LHA: Wakefulness regulation
Internal Regulation
Homeostasis
Maintains biological processes within narrow set ranges (set point vs. settling point)
Uses negative feedback to maintain stability
Hypothalamus: Key control center for these processes
Components of Integrated Response
Autonomic: Fast response adjusting nerve component balance
Endocrine: Slow response involving hormone release
Somatic: Motivating behavioral changes
Hypothalamus Functions
PVN: Initiates autonomic/endocrine responses; controls several hormones
Different components responding to fast and slow processes
Regulation Mechanisms
Autonomic responses: Body’s adjustments like sweating or shivering
Endocrine responses: Metabolic changes and thermoregulatory responses through hormonal adjustments
Somatic responses: Behavioral adjustments to internal and external temperatures
Body Temperature Regulation
Key neurons located in medial preoptic and anterior nuclei
These neurons integrate input on external/internal temperature
Osmotic and Hypovolemic Thirst
Osmotic Thirst Receptors
Monitors osmotic pressure; OVLT & SFO detect cell shrinkage
Response:
Endocrine: release of ADH to conserve water
Somatic: Generate the desire to drink
Hypovolemic Thirst
Baroreceptors: Detect pressure changes related to blood volume
Hypotension initiates conservation of water via nuclei activation in the hypothalamus
Energy Balance and Long-term Regulation
Energy Regulation
Brain must acquire glucose to produce ATP (energy)
Different states:
Prandial (fed state): storing glucose into glycogen
Fasting: breaking down stored molecules for energy
Long-term Regulation
Stable body weight linked to homeostatic and hedonic mechanisms
Lipostatic Hypothesis: The brain monitors body fat; leptin indicates fat energy storage
Implications of the hypothalamic nuclei regulation in energy needs
Neural Regulation of Appetite
Hunger Signals
Autonomic response to activating rest & digest functions
Endocrine adjustments lowering metabolic rate
Somatic: Initiate feeding behavior through orexin and MCH
Satiety Signals
Activate sympathetic system encouraging energy expenditure
Endocrine responses increasing metabolic rate
Somatic suppression of feeding behavior
Hedonic Mechanisms
Eating driven by emotional and motivational aspects linked to dopamine and serotonin
Eating Disorders
Anorexia: Low motivation and suppressed appetite
Bulimia Nervosa: Binge eating followed by purging due to high motivation
Hormones and Sex
Steroid Hormones: Three types influencing sexual behavior
Androgens (testosterone)
Estrogen (estradiol)
Progestogens
Endocrine System Regulation
Gonadal hormone release controlled by hypothalamus actions
Hypothalamic Inputs
Arcuate Nucleus: Monitors male hormone levels
Anteroventral PN: Monitors female hormone levels; feedback mechanisms in place
Fetal Development
Gonadal Development: Influences from Sry gene determine male/female structures
Duct Development: Hormonal influences define external and internal structures
Hormonal Mechanisms of Sexual Behavior
Male and female sexual drive regulation influenced by testosterone and cyclical hormonal surges
Brain Mechanisms of Sexual Behavior
Reward circuits and areas of the brain involved in sexual behavior identification
Language and Speech
Language Features
Human language’s distinguishing features and comparison to animal communication
Language Evolution Theories
Various theories discussing origin and development of language abilities
Lateralization and Localization of Language
Areas of the cortex engaged in understanding and producing language
Wernicke-Geschwind Model
Processing spoken and written language through specialized pathways
Aphasias
Different types of language deficits based on brain damage locations
Language Localization
Evidence suggesting language areas are not strictly localized, but spread out
Other Languages and Dyslexia
Processing of sign language and bilingualism in the brain, alongside dyslexia observations
Learning and Memory
Memory Types and Definitions
Distinctions between short-term and long-term memory, including explicit and implicit categories
Memory Engram and Long-term Potentiation
Processes involved in memory formation and consolidation mechanisms
Alzheimer’s Disease & Memory
Effects on memory and types of memory affected by the disease
Conclusion on Memory Structures
Summary of the neuroanatomical basis for different types of memories bespeaking distinct brain regions.
Angular gyrus: translates the visual code from reading into an auditory code
Wernicke’s area: where meaning of words is understood; further translates thought processes into verbal responses
Arcuate fasciculus: fibers that connect Broca’s area to Wernicke’s area
Broca’s area: activates the appropriate programs that drive the neurons of the primary
