History & Early Theorie
Hippocrates → correctly located the mind in the brain.
• Aristotle → believed the mind was in the heart (warmth/vitality).
• Franz Gall (early 1800s) → Phrenology (study of skull bumps to reveal mental abilities and traits).
• Popular in Britain & America.
• Mark Twain’s test: inconsistent phrenology readings exposed its flaws.
• Importance: Although false, phrenology focused attention on localization of function (specific brain regions → specific functions).
Biological Psychology
Nervous system operates similarly across humans and animals → allows scientists to study simpler species.
• Neurons = building blocks of the nervous system.
• New neurons are born throughout life; unused neurons die off.
• Structure of a Neuron:
• Cell body (soma): contains nucleus; life-support center.
• Dendrites: bushy fibers that receive & integrate messages → toward cell body. (“Dendrites listen.”)
• Axon: single long fiber that sends messages to other neurons, muscles, or glands. (“Axons speak.”)
• Terminal branches: release messages into synaptic gap.
Key terms
Biological psychology: study of how biology influences psychology.
• Plasticity: brain’s ability to change & adapt.
• Neuron: basic nerve cell.
• Cell body: neuron’s life-support center.
• Dendrites: receive & carry messages toward cell body.
• Axon: sends messages away from cell body to other neurons/muscles/glands.
Synapses & Neurotransmission
• Synapse = junction between axon tip of sending neuron & dendrite/cell body of receiving neuron.
• Synaptic gap (cleft) = tiny space between neurons.
• Neurotransmitters = chemical messengers that cross the synaptic gap, bind to receptors, and excite or inhibit next neuron.
• Reuptake = reabsorption of excess neurotransmitters by sending neuron.
• Other fates: broken down by enzymes, drift away.
Key Scientists
• Charles Sherrington → discovered synapses (delays in transmission).
• Ramón y Cajal → described neurons as “protoplasmic kisses” (they don’t touch).
• Candace Pert & Solomon Snyder (1973) → discovered endorphins (natural opiates).
Agonists vs Antagonists
Agonist = increases neurotransmitter action.
• Ex: morphine mimics endorphins → produces “high.”
• Drugs may boost release, block reuptake, or mimic neurotransmitters.
• Antagonist = blocks neurotransmitter action.
• Ex: Curare → blocks ACh receptor sites → paralysis.
• Botulin (Botox) → blocks ACh release → temporary paralysis of muscles.
Neurogenesis
Definition: Formation of new neurons.
• Found in mice, birds, monkeys, humans (He & Jin, 2016; Jessberger et al., 2008).
• Baby neurons migrate and form connections (Aimone et al., 2010).
• Stem cells: can develop into any brain cell; studied for regeneration (Lu et al., 2016).
• Possible future → “reseeding” damaged brains.
• Promoters of neurogenesis:
• Exercise (Sexton et al., 2016)
• Sleep
• Stimulating, low-stress environments (Iso et al., 2007; Pereira et al., 2007)
The Divided Brain
Hemispheric Specialization
• Left hemisphere: reading, writing, speaking, arithmetic, understanding.
• Right hemisphere: less dramatic deficits after damage, but important for inference, self-awareness, spatial & perceptual tasks.
Visual Wiring Basics
• Left visual field → right hemisphere.
• Right visual field → left hemisphere (speech center).
• Normally info crosses via corpus callosum; in split brain, it doesn’t.
Important Factoids
Brain plasticity is greater in children than adults.
• Blind/deaf brains repurpose unused areas.
• Phantom limb → cortical remapping (e.g., foot → genitals).
• Neurogenesis = natural but rare; can be encouraged with lifestyle.
• Split-brain patients = normal personality, but reveal independent hemisphere function.
• Left hemisphere = interpreter, right hemisphere = nonverbal knowledge.
• Dogs also process words (left hemisphere) and intonation (right hemisphere) like humans (Andics et al., 2016).
Key Concepts
Behavior Genetics
Behavior genetics = study of how genes (heredity) and environment (experience) influence behavior.
• Heredity = genetic transfer of traits from parents to offspring.
• Environment = every nongenetic influence (prenatal nutrition → social support, culture, etc.).
• Big Q: What makes us alike as humans, and what makes us unique individuals?
Genetic
Chromosomes = 46 total (23 pairs; half from each parent). Threadlike DNA structures.
• DNA = molecule carrying genetic info.
• Genes = segments of DNA that code for proteins → building blocks of body. Can be expressed (active) or inactive.
• Example: Hot water turns on a tea bag → environment can “turn on” genes.
• Genome = complete instructions for making an organism. Humans share 20,000 genes.
💡 Factoids
• Humans are 99.9% genetically identical.
• Humans share 50% of genes with bananas (Robert May).
• Shared DNA = what makes us human (vs. chimpanzee, tulip, etc.).
• Variations at gene sites explain individual differences (e.g., anxiety, height, disease risk).
Consciousness
Consciousness = our awareness of ourselves & environment.
• Helps us reflect, adapt, and plan.
• Early psychology defined as the study of consciousness → Behaviorism (1900s) ignored it → later revived with neuroscience (1960s).
• Altered states: daydreaming, hypnosis, meditation, drugs, dreaming, etc.
Key Terms (Know These!)
ehavior genetics: study of hereditary vs. environmental influences.
• Chromosomes: DNA structures carrying genes.
• DNA: molecule containing genetic info.
• Genes: DNA segments coding for proteins.
• Genome: complete set of genetic instructions.
• Heredity: genetic transfer of traits.
• Environment: all external influences.
• Interaction: effect of environment depends on heredity.
• Epigenetics: environment affecting gene expression.
• Evolutionary psychology: how natural selection shapes behavior.
• Natural selection: traits aiding survival/reproduction get passed on.
Key terms
• Consciousness: subjective awareness of self & environment.
• Cognitive neuroscience: study of brain activity linked with cognition.
• Selective attention: focusing conscious awareness on one stimulus.
• Inattentional blindness: failure to notice visible objects when attention diverted.
• Dual processing: conscious “high road” + unconscious “low road” operating together.
• Blindsight: condition where a person can respond to visual stimuli without consciously perceiving them.
Biological Rhythms
• Sleep: A periodic, natural loss of consciousness (different from coma, anesthesia, hibernation).
• Circadian rhythm: Biological clock on a 24-hour cycle (controls temp, wakefulness, alertness).
• Morning = ↑ body temp
• Afternoon dip = siestas common
• Evening = ↓ body temp
• Owls vs. Larks:
• Young adults → night owls (alert later).
• Older adults → morning larks (wake early, fragile sleep).
• Morning types: more punctual, better grades, less depression.
• Night owls: creative, smart.
Why Do We Sleep? (5 Functions)
- Protects (evolutionary): safer in cave at night.
- Recuperates: restores immune system, repairs brain tissue, cleans waste.
- Restores memories: consolidates learning, replays experiences.
- Feeds creativity: boosts problem-solving & connections.
- Supports growth: pituitary releases growth hormone in deep sleep.
Sleep Deprivation
Sleep debt: brain keeps track; can’t be “paid off” in one night.
• Effects:
• Mood: irritability, depression (71% higher risk if <5 hrs).
• Cognition: poor focus, memory, slower reaction.
• Physical: weaker immune system, ↑ risk colds, cancer, shorter lifespan.
• Weight gain:
• ↑ ghrelin (hunger), ↓ leptin (satiety).
• ↓ metabolism, ↑ cortisol (fat storage).
• Brain craves fatty foods.
• Driving risks: drowsy driving = drunk driving levels.
💡 Factoid: Sleep loss increases crash risk in teens & truckers; U.S. Navy prescribed “more sleep” after ship collisions (2017).
