Biological Basis of Behavior - Unit 2 AP Psychology

Heredity and Environment

  • Heredity: Passing traits from one generation to another.
    • Charles Darwin focused on the impact of heredity and environment.
    • Theory of Evolution: Natural selection favors beneficial traits for survival.
  • Heritability: Mathematical measure of genetic variation in a population.
    • Ranges from 0 to 1.
    • Example: Heritability of 0.6 means 60% of trait variation is genetic, and 40% is environmental.
  • Nature vs. Nurture: Debate over genetics versus environment in shaping individuals.
    • Psychological perspectives differ: Darwin leans towards nature.
  • Epigenetics: How environment and behavior affect gene expression (DNA sequence not changed).
    • Genes are turned on or off due to sustained environmental pressure.
  • Reciprocal Determinism: (Unit 7) Environment, behavior, and individual beliefs impact each other.

Endocrine System

  • Body's glands producing hormones to regulate biological processes.
  • Works with nervous system to send information throughout the body.
  • Nervous System
    • Uses neurons.
    • Fast, short-lived messages to localized areas.
  • Endocrine System
    • Uses glands to create hormones.
    • Slower messages targeting broad areas.
  • Homeostasis: Body's ability to maintain internal stability.
    • Example: Maintaining a body temperature around 98 degrees Fahrenheit.

Glands and Hormones

  • Hypothalamus
    • Part of the brain that controls the pituitary gland.
    • Directs autonomic functions.
  • Pituitary Gland
    • Releases growth hormones, oxytocin, and vasopressin.
    • Communicates with other glands.
    • Sometimes called "master gland".
  • Pineal Gland
    • Above the brainstem.
    • Regulates sleep cycles.
    • Produces melatonin.
  • Thyroid and Parathyroid Glands
    • In the throat.
    • Regulate metabolism, growth, nervous system, and calcium levels.
    • Hormones: thyroid hormones, parathyroid hormones, calcitonin.
  • Adrenal Glands
    • Above the kidneys.
    • Regulate salt levels, blood pressure, and oxygen intake.
    • Hormones: norepinephrine, epinephrine, and aldosterone.
  • Pancreas
    • Near the stomach.
    • Produces insulin and glucagon.
    • Regulates sugar levels.
  • Gonads
    • Ovaries or testes.
    • Produce testosterone, estrogen, and progesterone.
    • Enable reproduction.

Nervous System

  • Made up of the central nervous system (CNS) and the peripheral nervous system (PNS).

Central Nervous System (CNS)

  • Brain and spinal cord.
  • Sends orders to the body.

Peripheral Nervous System (PNS)

  • Nerves branching off brain and spine.
  • Communicates with the rest of the body.
Divisions of PNS
  • Sensory (Afferent) Division: Conducts impulses from sensory stimuli to the CNS.
  • Motor (Efferent) Division: Sends signals from the brain and spinal cord to muscles and glands.
    • Afferent approaches the brain, Efferent exits the brain.
Motor Division
  • Somatic Nervous System
    • Five senses and skeletal muscle movement.
    • Conscious and voluntary movements.
  • Autonomic Nervous System
    • Involuntary activities.
    • Heartbeat, digestion, breathing.
Autonomic Nervous System
  • Sympathetic Division: Mobilizes the body for action.
    • Increases heart rate, dilates eyes, increases breathing.
  • Parasympathetic Division: Relaxes the body.
    • Slows heart rate, increases digestion, stores energy.
  • Work together in emergencies for fight or flight response.
  • Glial Cells: Support the nervous system (do not process information).
Neuron
  • Basic functional unit of the nervous system.
  • Communicate using electrical and chemical signals.
  • Complete the study guide to identify the different parts of the neuron and their functions.

Neuron Communication

  • Neurons need enough stimulation to cause an action potential.
  • Action Potential: Neuron fires and sends an impulse down the axon.
  • Positively and negatively charged ions create potential.
  • Permeability: Some ions cross the membrane more easily.
  • Resting Potential: Neuron not sending a signal (more negative ions inside).
  • Depolarization: Stimulus meets the threshold, causing the neuron to fire.
    • All-or-nothing response.
  • Repolarization: Neuron returns to resting potential.
  • Refractory Period: Neuron cannot respond to another stimulus until repolarization is complete.
  • Synapse: Tiny space between neurons where signals are converted and sent.
  • Chemical Synapses: Use neurotransmitters (chemical messengers).
  • Electrical Synapses: For quick, immediate messages.
  • Synaptic Gap: Narrow space between the presynaptic terminal and postsynaptic terminal.
  • Presynaptic Terminal: Axon terminal of the sending neuron converts the electrical signal to a chemical one and sends the neurotransmitters into the synaptic gap.
  • Postsynaptic Terminal: Where neurotransmitters are accepted in the dendrites of the receiving neuron.
  • Reuptake: Sending neuron reabsorbs extra neurotransmitters.
  • Excitatory Neurotransmitters: Increase likelihood of neuron firing through depolarization.
  • Inhibitory Neurotransmitters: Decrease likelihood of neuron firing, leading to hyperpolarization.
Chain of Events
  1. Action potential sends a signal down the axon of a neuron to the presynaptic terminal.
  2. Channels in the axon terminal are opened and the neurotransmitters are released into the synaptic gap.
  3. Neurotransmitters diffuse through the synaptic gap and bind to receptor sites in the postsynaptic terminal.
  4. Neurotransmitters unbind with the receptors, some are destroyed, and others go through the process of reuptake.
Neurotransmitters
  • Acetylcholine: Muscle action, learning, memory.
  • Dopamine: Movement, learning, attention, emotion.
  • Serotonin: Hunger, sleep, arousal, mood.
  • Endorphins: Pain control, pain tolerance.
  • Epinephrine: Response to emotional situations, memory formation.
  • Norepinephrine: Blood pressure, heart rate, alertness, fight or flight response.
  • Glutamate: Long-term memory, learning.
  • GABA: Sleep movement, slows down nervous system.

Drugs and Neural Firing

  • Agonist Drugs: Increase neurotransmitter effectiveness.
    • Mimic neurotransmitters or block reuptake, making them more available.
    • Examples: Anti-anxiety medications (Xanax), Prozac, Opioids.
  • Antagonist Drugs: Decrease neurotransmitter effectiveness.
    • Block neurotransmitter release or bind to postsynaptic receptors.
    • Examples: Schizophrenia medication, alcohol.

Brain Structures

  • Broca's Area: Facial muscles for speech.
    • Damage results in Broca's aphasia (loss of speech production).
  • Wernicke's Area: Creates meaningful speech.
    • Damage results in Wernicke's aphasia (loss of meaningful speech).
  • Medulla Oblongata: Cardiovascular and respiratory regulation, autonomic functions.
  • Pons: Connects medulla and cerebellum, coordinates movement, sleep and dream.
  • Cerebellum: Balance, coordination.
  • Brainstem: Medulla, pons, midbrain, controls autonomic functions, damage can be fatal.
  • Spinal Cord: Connects brain to body.
  • Midbrain: Sends visual and auditory information, relay station.
  • Reticular Formation: Arousal in sleep and awake cycle.
  • Reticular Activating System: Stimulates higher centers when something important happens.

Forebrain

  • Cerebrum: Complex thoughts.
  • Cerebral Cortex: Covers the whole brain processes information.
  • Corpus Callosum: Nerve fibers connecting hemispheres.
Lobes
  • Frontal Lobe: Higher-level thinking.
    • Prefrontal Cortex: Foresight, judgment, speech.
    • Motor Cortex: Voluntary movement.
      • Left controls right side, Right controls left side.
      • Represented by the motor homunculus.
  • Parietal Lobe: Sensory information (touch, pain, temperature).
    • Somatosensory Cortex: Registers touch and movement sensations.
      • Left controls right side, Right controls left side.
      • Represented by sensory homunculus.
  • Occipital Lobe: Visual cortex for seeing.
  • Temporal Lobe: Face recognition, smell, hearing, balance, memory, Wernicke's area.
    • Angular Gyrus: Reads words and transfers that information into an auditory form.
    • Auditory Cortex: Processes different sounds.
Sensory Information
  • Thalamus: Sends sensory information to the forebrain.
  • Limbic System: Emotions, learning, memory.
    • Hippocampus: Creates memories (not stored here).
    • Amygdala: Emotional reactions (fear, anxiety, aggression).
    • Hypothalamus: Homeostasis, controls drives (hunger, thirst), works with the pituitary gland.
    • Nucleus Accumbus: Drug dependency, pleasure, reward, motivation.
    • Basal Ganglia: Intentional body movement.

Brain Regions

  • Hindbrain: Bottom of the brain.
  • Midbrain: Above the base of the brain surrounded by the forebrain.
  • Forebrain: Top of the brain.
  • Brain Lateralization: Differing functions of left and right hemispheres.
    • Left: words, language.
    • Right: spatial concepts.

Examining The Brain

  • Phineas Gage: Rod through head damaged limbic system and prefrontal cortex, personality change.
  • Roger Sperry & Michael Gazzaniga: Split-brain research (cut corpus callosum).
    • Left hemisphere: language.
    • Right hemisphere: spatial.
  • Lesion Studies: Destroy specific brain parts for insight.
  • Autopsy: Examination of body after death.

Neuroimaging Techniques

  • EEGs: Electrodes record electrical signals from neurons for sleep and seizure research.
  • CTs: Advanced x-rays to locate brain damage or tumors.
  • PET Scans: Radioactive glucose tracks brain activity in real time.
  • MRIs: Detailed brain pictures using a strong magnetic field.
  • FMRIs: Similar to MRI, shows metabolic functions for detailed brain activity.

Brain Plasticity

  • Changes, modifies, or repairs itself called neuroplasticity.
  • Learning constantly causes neuroplasticity to occur.
  • Brain damage from infections, neurotoxins, genetic factors, head injuries, tumors, or even stroke can have life altering impacts.
  • Learning creates neural pathways, which develop with practice.
  • Consciousness: When an individual is awake and aware of their own external stimuli or mental activity.
    • William James; consciousness as a stream.
    • Freud: conscious, subconscious, and unconscious mind.
  • Psychoactive Substances: Alter perception, consciousness, or mood.

Types of Drugs

  • Depressants: Reduce neural activity, cause drowsiness, muscle relaxation, lowered breathing, and if abused, possibly death.
    • Examples: alcohol, sleeping pills.
  • Opioids: Function as a depressants while have their own category due to their addictive nature which gives an individual pain relief.
    • Examples: morphine, heroin, oxycodone.
  • Stimulants: Excite and promote neural activity, energy, reduce appetite, irritability.
    • Examples: caffeine, nicotine, cocaine.
  • Hallucinogens: Cause hallucinations, reduce motivation.
    • Examples: marijuana, piety, or LSD.

Sleep and Dreaming

  • Circadian Rhythm: Biological clock that regulates sleep/wake cycle.

Theories on Why We Sleep

  • Restoration Theory: Restore energy and resources.
  • Adaptive Theory: Conserve energy for survival.
  • Information Processing Theory: Restore and build memories.
Brain Waves for Sleep
  • Alpha waves: slower waves that have a high amplitude.
  • Beta waves: Low amplitude and are the fastest brain waves.
  • Theta waves: Great amplitude compared to beta and alpha waves and are even slower in frequency.
  • Delta waves: Greatest amplitude and slowest frequency.
Stages of Sleep
  • Non-REM Stage 1
    • Light sleep. The body will start to relax and mind starts to slow.
  • Non-REM Stage 2
    • Lasts around ten to twenty minutes where an individual will experience K complexes and sleep spindles.
  • Non-REM Stage 3
    • One of the deepest states of sleep where growth hormones are produced and an individualmay experience sleepwalking or sleeptalking.
  • REM
    • Rapid eye movement. External muscles are paralyzed while internal muscles and structure become active.
Hypnagogic Sensations
  • Sensations that you might imagine are real that happen when you're in a light sleep.
Theories on Dreams
  • Activation Synthesis Model: Brain trying to make sense of random neural activity.
  • Cognitive Development Theory: Dreams reflect cognitive development.
  • Activation Theory: Specific areas of the brain activated create different dream content.
  • Physiological Function Approach: Dreams stimulate and preserve neural pathways.
Sleep Disorders
  • Insomnia: Trouble falling or staying asleep.
  • Sleep Apnea: Breathing problems disrupt sleep.
  • Sleep terrors/night terrors: Intense fear while sleeping leading to disrupted schedule.
  • Narcolepsy: Uncontrollably falls asleep during the day