PP

Biological Bases of Behavior

02.01 Heredity & Environment

  • Psychology = study of behavior πŸ‘€ + mental processes πŸ’­
    • Behavior: measurable (ex: how many times a student checks their phone).
    • Mental Processes: invisible (ex: nerves before a speech).
  • Eugenics 🚫: Used unethically to justify racism by promoting selective breeding.
  • Animals vs Humans 🐭 vs πŸ‘©: Easier to change animal DNA (fewer laws, less ethical concern).
  • Food Preferences 🍩πŸ₯“: Humans crave sweet/fatty foods because ancestors needed survival energy.
  • Chromosomes β†’ DNA β†’ Genes 🧬: Genes carry instructions.
  • Not all 20,000 genes are active πŸ”‘: Environment can β€œturn on/off” genes.
  • Twins πŸ‘―:
    • Identical = same DNA, always same sex, very alike.
    • Fraternal = 50% DNA, can be diff. sexes, may look different.
  • Adoption Studies 󰔧: Separate genetics vs environment effects.
  • Environment vs Heredity:
    • Environment β†’ attitudes, values, faith.
    • Heredity β†’ personality, intelligence potential.
  • Epigenetics πŸ§ͺ: Life events (stress, nutrition, social contact) change gene expression.

02.02 Nervous System

  • πŸ‘‰ In Your Own Words: β€œNurture works on what nature provides” β†’ born with traits, but environment shapes how they grow.
  • πŸ‘‰ In Your Own Words: Siblings can be very different because of temperament, parenting styles, and heritability.
  • Nervous System = communication system πŸ“‘.
  • Neurons β†’ Electrical signal β†’ Neurotransmitters at synapse β†’ Next neuron.
  • Neuron types:
    • Sensory – carry info in.
    • Motor – send commands out.
    • Interneurons – link the two.
  • Reflex Arc ⚑: Quick, automatic spinal response (ex: touching hot stove).
  • Central Nervous System 🧠 = brain + spinal cord.
  • Peripheral Nervous System 🦡 = nerves to/from body.
    • Somatic β†’ voluntary movement.
    • Autonomic β†’ involuntary:
    • Sympathetic 😱 = fight/flight.
    • Parasympathetic 😌 = rest/digest.
  • πŸ‘‰ In Your Own Words: Central Nervous System makes decisions, Peripheral Nervous System carries input/output. Autonomic NS keeps the body balanced (sympathetic arouses, parasympathetic calms).

02.03 Neurons & Firing

  • Neuron Parts 🧩:
    • Dendrites 🌿 – receive.
    • Cell Body 🟒 – process.
    • Axon ➑️ – send.
    • Myelin Sheath 🧈 – speed; loss β†’ MS (weak muscles, vision problems).
    • Synapse ⚑ – gap between neurons.
  • Firing:
    • All-or-None Principle β†’ fires fully or not at all.
    • Excitatory πŸš€ β†’ increases chance of firing.
    • Inhibitory πŸ›‘ β†’ decreases chance.
  • Neurotransmitters:
    • ACh πŸ’ͺ – muscles, memory (low = Alzheimer’s).
    • Dopamine πŸ˜ƒ – movement, reward (high = schizophrenia, low = Parkinson’s).
    • Serotonin πŸ™‚ – mood, hunger, sleep (low = depression).
    • Endorphins πŸƒ – pain relief, pleasure.
    • GABA πŸ’€ – calming (low = seizures, insomnia).
    • Glutamate ⚑ – excitatory, learning (too much = seizures).
  • Reuptake πŸ”„: NTs reabsorbed after firing. (Prozac stops serotonin reuptake β†’ improves mood).
  • πŸ‘‰ In Your Own Words: Neurons fire the same strength, but stronger stimuli = more neurons firing & firing more often.

02.04 The Brain

  • πŸ‘‰ In Your Own Words: Neurons = send messages, Glial cells = support & protect neurons.
  • Drugs πŸ’Š:
    • Agonist = mimics NT (ex: dopamine agonist for Parkinson’s).
    • Antagonist = blocks NT (ex: antipsychotics block dopamine in schizophrenia).
  • Endocrine System 🩸: Hormones act slower but last longer (ex: pituitary β€œmaster gland”). πŸ—
  • Lesson 02.04 – The Brain
  • Biopsychosocial Approach βš–οΈ: Combines biological, psychological, and social factors β†’ best explanation.
  • Neuroplasticity 🧩: Brain rewires after damage. Blind/deaf β†’ other senses strengthen.
  • Brain Tools: EEG, CT, MRI, fMRI, PET, MEG.
  • Divisions:
    • Hindbrain πŸ«€ – medulla (breathing), cerebellum (balance).
    • Midbrain πŸ‘ – sensory processing, movement.
    • Forebrain πŸ’­ – reasoning, memory.
  • Limbic System:
    • Amygdala 😑😱 – emotion, fear.
    • Hippocampus πŸ“š – memory (shrinks w/ age).
    • Hypothalamus πŸ” – hunger, thirst, hormones.
  • Cerebral Cortex:
    • Frontal lobe – planning, judgment, movement.
    • Parietal – touch, sensation.
    • Temporal – hearing, language.
    • Occipital – vision.
    • Motor cortex β†’ movement.
    • Somatosensory cortex β†’ touch.
    • Association areas β†’ higher learning & thinking.
  • Hemispheres:
    • Left πŸ“ – language, logic.
    • Right 🎨 – creativity, spatial.
  • πŸ‘‰ In Your Own Words: Must follow ethics (consent, minimize harm, privacy) in brain studies.

02.05 – Sleep

  • Consciousness = awareness of environment/self.
  • Processing:
    • Dual βš–οΈ – conscious + unconscious.
    • Parallel πŸ”„ – many things at once.
    • Sequential ➑️ – step by step.
  • Sleep Stages:
    • N1 – light sleep, falling feeling.
    • N2 – spindles (bursts of activity).
    • N3 – deep delta sleep.
    • REM πŸŒ™ – vivid dreams, brain active, body paralyzed.
  • Sleep Cycle ⏰: ~90 minutes.
  • Sleep Loss β†’ obesity, poor memory, high blood pressure, weak immune system.
  • Disorders: insomnia, narcolepsy, sleep apnea, REM disorder, night terrors.
  • Dream Theories:
    • Info-Processing πŸ“‚ – organize memories.
    • Activation-Synthesis ⚑ – brain makes sense of random activity.
  • πŸ‘‰ In Your Own Words: Sleep = natural, reversible loss of consciousness.
  • πŸ‘‰ In Your Own Words: We use 100% of our brain (different parts active at different times). πŸ‘

02.06 – Sensation & Vision

  • Sensation πŸ‘‚πŸ‘ƒπŸ‘πŸ‘… = detecting input.
  • Perception πŸ’­ = interpreting input.
  • Thresholds:
    • Absolute = smallest detectable stimulus.
    • JND = smallest change noticed.
    • Weber’s Law πŸ“ = difference must be proportional.
  • Adaptation: Stop noticing constant input (ex: smell of candle).
  • Vision Path πŸ‘: Cornea β†’ Pupil β†’ Lens β†’ Retina β†’ Rods/Cones β†’ Bipolar cells β†’ Ganglion cells β†’ Optic Nerve β†’ Brain.
  • Rods vs Cones:
    • Rods πŸŒ‘ – dim light, b&w.
    • Cones 🌈 – color, detail.
  • Blind Spot: No receptors.
  • Color Theories:
    • Trichromatic β†’ RGB cones.
    • Opponent-Process β†’ red/green, blue/yellow pairs.
  • πŸ‘‰ In Your Own Words: Bottom-up = raw data β†’ brain; Top-down = brain shapes perception.
  • πŸ‘‰ In Your Own Words: Weber’s Law = need proportional change to notice difference.

02.07 – Hearing & Other Senses

  • Frequency = Pitch 🎢: high frequency = high pitch, low frequency = low pitch.

  • Amplitude = Loudness πŸ”Š: bigger wave = louder sound.

  • Sound Path: Outer Ear β†’ Eardrum β†’ Ossicles β†’ Cochlea β†’ Hair Cells β†’ Auditory Nerve β†’ Brain.

  • Theories:

    • Place Theory β†’ pitch = location on cochlea.
    • Frequency Theory β†’ pitch = firing rate of neurons.
    • Volley Theory β†’ groups of neurons fire in rotation for high frequencies.

  • Hearing Loss:

    • Conductive = outer/middle ear damage.
    • Sensorineural = inner ear/nerve damage.

  • Touch 🀲: Pressure, warmth, cold, pain.

  • Taste πŸ‘…: Sweet, sour, salty, bitter, umami, fatty.

  • Smell πŸ‘ƒ: Directly linked to memory & emotion.

  • Balance βš–οΈ: Vestibular (inner ear fluid) + Kinesthesis (body position).

  • Pain = Bio + Psych + Social:

    • Bio β†’ nerve signals, endorphins.
    • Psych β†’ attention, expectations.
    • Social β†’ culture, presence of others.

  • πŸ‘‰ In Your Own Words: Closing eyes helps locate sound better by removing distractions.

  • πŸ‘‰ In Your Own Words: Sensory Interaction = senses combine (ex: skateboard β†’ vestibular for balance + kinesthetic for movement).