Biological Psychology and Human Development Lecture Notes

Foundations of Biological Psychology

• Definition and Scope: Biological Psychology is the scientific study that connects biology with behavior. It is a field that aims to understand the physiological underpinnings of mental processes and actions.
• Historical Context: Science existed prior to the discovery of neurons, but the identification of these specialized cells made modern Biological Psychology possible.
• Neurons as Fundamental Units: Neurons are the building blocks of the nervous system. The field explores how these cells communicate to produce the vast array of human experiences.

Structure and Function of the Neuron

• The Prototypical Neuron Structure:
  • Dendrites: These are the branching extensions of a neuron that receive chemical messages from other neurons or are signaled by sensory receptors. Their primary task is to take information toward the cell body.
  • Cell Body (Soma): This serves as the life support center for the neuron. It contains the nucleus.
  • Nucleus: The central part of the cell body containing the genetic material.
  • Axon: A long, slender fiber that takes messages away from the cell body and transmits them to other neurons, muscles, or glands.
  • Myelin Sheath: A fatty cover often found surrounding the axon. Its primary purpose is to insulate the axon and make electrical signals move faster.
  • Nodes of Ranvier: Gaps in the myelin sheath along the axon.
  • Schwann's Cells: Cells that produce the myelin sheath.
  • Terminal Branches (Axon Terminals): These branch out from the axon toward other neurons to deliver signals.
• Neural Communication Process:
  • Input: Dendrites receive chemical messages.
  • Transmission: These messages are brought to the cell body. If the stimulus is strong enough, an electrical charge is fired down the axon.
  • Action Potential: The triggering of an action potential depends entirely on whether a specific electrical threshold is met.
• Principles of Firing:
  • Excitatory vs. Inhibitory Signals: Neurons receive both types of signals from neighboring cells. Excitatory signals act like an accelerator, while inhibitory signals act like a brake.
  • All-or-None Response: A neuron either fires or it does not. Increasing the intensity of the excitatory signal beyond the threshold does not increase the intensity of the response; it is a binary state.
• Communication Between Neurons:
  • Synapse: Neurons are separated by small gaps called synapses. There is a physical gap between the terminal branches of the sending neuron and the dendrites of the receiving neuron.
  • Neurotransmitters: These are chemical messengers released from the terminal branches of the sending neuron into the synaptic gap. They bind to specific receptor sites on the receiving neuron.
  • Reuptake: Excess neurotransmitters that do not bind to receptors are reabsorbed or recycled by the sending neuron.

Major Neurotransmitters and Their Effects

• Diversity of Pathways: There are many different kinds of neurotransmitters, and they follow distinct pathways in the brain, each influencing emotions and behaviors uniquely.
• Key Neurotransmitters:
  • Acetylcholine ($ACh$): Released during muscle contraction. It plays a critical role in attention, learning, and memory.
  • Endorphins: These function similarly to morphine, acting as natural painkillers. They are released during exercise, which is why humans are more likely to have a positive mood after physical activity. They produce feelings of pleasure and are released so that a person may not feel an injury immediately during intense exertion.
  • Dopamine: Involved in movement, learning, attention, and emotion. It is heavily involved in reward pathways and is closely related to addiction (e.g., to phones or drugs).
    • Clinical Implications: A lack of dopamine is found in individuals with Parkinson's disease. An excess of dopamine is linked to hallucinations and Schizophrenia.
    • Drug Analogy: Methamphetamine is almost identical to dopamine; the body cannot distinguish between the two, leading to a massive dopamine surge or "high."
  • Serotonin: Influences mood, hunger, sleep, pain, and arousal. Many antidepressant medications target serotonin levels.
  • Glutamate: Known as the "gas pedal" of the nervous system because it is able to stimulate almost all neurons, causing them to fire.
  • GABA: Known as the "brake pedal." It inhibits neurons and prevents them from firing.

Influence of Drugs and Chemical Substances

• Definition of Drug: In this context, a drug is anything that affects neurotransmitters.
• Mechanism of Action:
  • Agonist: A substance that excites neurons. It may mimic a neurotransmitter or block the reuptake process so the neurotransmitter remains in the synapse longer.
  • Antagonist: A substance that inhibits neurons. It may stop the release of neurotransmitters by the sending neuron or bind to a receptor site without activating the neuron, thereby blocking the real neurotransmitter from binding.
• Examples of Drug Action:
  • Botox: Functions as an antagonist for Acetylcholine ($ACh$), preventing muscle contraction (leading to the smoothing of wrinkles).
  • Antipsychotics: Act as antagonists for Dopamine to treat conditions like schizophrenia.
• Addiction and Withdrawal:
  • With constant drug use, the brain may stop producing its own natural neurotransmitters (e.g., stopping dopamine production).
  • When the drug is withdrawn, the body no longer has those neurotransmitters available, resulting in withdrawal symptoms.
  • While the brain might recover, it can take years for natural production to return.

Organization of the Nervous System

• The Electrochemical Communication Network: The nervous system is divided into two primary parts.
• Central Nervous System ($CNS$): Consists of the Brain and the Spinal Cord. This is where the majority of neurons are located.
• Peripheral Nervous System ($PNS$): Connects the $CNS$ to the rest of the body.
  • Nerves: These are bundles of axons in the $PNS$ that carry information from the $CNS$ to the body.
• Types of Neurons:
  • Sensory Neurons: These carry information from sensory receptors toward the brain and spinal cord.
  • Motor Neurons: These carry messages away from the brain and spinal cord to reach the muscles and glands.
• Divisions of the Peripheral Nervous System:
  • Somatic Nervous System: Controls sensory receptors and skeletal muscles. It is responsible for voluntary movement.
  • Autonomic Nervous System ($ANS$): Controls the glands and muscles of internal organs. It is responsible for involuntary movements like heartbeat and breathing.
    • Sympathetic Nervous System: The "revving up" system. It arouses the body during stressors, initiating the "fight or flight" response. This includes accelerated heartbeat, raised blood pressure, dilated pupils, and increased confidence/strength.
    • Parasympathetic Nervous System: The "revving down" system. It calms the body after the sympathetic system has taken effect. It decreases heartbeat, lowers blood pressure, and contracts pupils.
• The Reflex Arc: A process where a signal goes from the somatic nervous system to the spinal cord and back through the somatic system before reaching the brain, allowing for rapid response.

The Endocrine System

• Hormonal Communication: This system works alongside the nervous system using chemical messengers called hormones.
• Process: Hormones are released by tissues or glands and travel through the bloodstream to other tissues and the brain.
• Comparison to Nervous System: The endocrine system is slower (reactions take seconds rather than milliseconds), but its influences last much longer because hormones continue to cycle through the bloodstream.
• Key Glands:
  • Adrenal Glands: Located on top of the kidneys. They release epinephrine (adrenaline) and norepinephrine, which help sustain the fight/flight response by increasing heart rate, blood pressure, and blood sugar.
  • Pituitary Gland: Controlled by the hypothalamus. It is known as the master gland because it releases hormones that cause other glands to release their own hormones. It also influences growth (growth hormones).
  • Other Glands: Parathyroids, thyroid, pancreas, ovaries, and testes.

Brain Anatomy and Function

• Older/Primitive Regions:
  • Brainstem: The oldest part of the brain, extending from the top of the spine to the midbrain. It controls basic life functions like heartbeat and breathing.
  • Reticular Formation: Located inside the brainstem. It filters sensory information and is involved in the sleep/wake cycle, equilibrium, and the Autonomic Nervous System.
  • Pons: Part of the brainstem that aids in coordinating movement.
  • Thalamus: Located on top of the brainstem. It acts as the brain's sensory hub, receiving all sensory information (except for smell) and movement data and sending it to higher brain regions.
  • Cerebellum ("Little Brain"): Located at the rear of the brain. It coordinates voluntary movement, modulates emotion, and helps discriminate sounds and structures. It is the seat of implicit memory (muscle memory).
• Limbic System (Emotional Brain): Located between the older parts and the cerebral hemispheres.
  • Hippocampus: Responsible for explicit memories, certain emotions, and spatial navigation.
  • Amygdala: Linked to aggression, fear, and survival emotions. It aids in recognizing emotions in others (empathy) and emotional memory.
  • Hypothalamus: Manages bodily maintenance and homeostasis (hunger, thirst, blood sugar, body temperature, sexual behavior). It triggers the pituitary gland.
• Cerebral Cortex (The Thinking Brain):
  • Cerebrum: The two large hemispheres (left and right).
  • Cerebral Cortex: The thin surface layer over the cerebrum. Its wrinkles allow a large surface area for processing to fit in a small space. The rest of the cerebrum consists mostly of axons moving information.

Lobes and Specialized Areas of the Cortex

• Four Lobes:
  • Frontal Lobe: Located at the front. Involved in "executive functioning," including impulse control, judgment, planning, and personality.
  • Parietal Lobe: Located at the top/rear. Processes spatial reasoning and perception of sensory input.
  • Occipital Lobe: Located at the back. Primarily responsible for vision.
  • Temporal Lobe: Located on the sides. Responsible for auditory processing and facial recognition.
• Functional Regions:
  • Motor Cortex: Located at the rear of the frontal lobes. It controls voluntary movements. Parts of the body requiring precise control (fingers, face) occupy larger areas of the motor cortex.
  • Sensory Cortex: Located at the front of the parietal lobes, parallel to the motor cortex. It handles touch and movement sensations. More sensitive body parts (lips, tongue) have larger areas dedicated to them.
• Language and Association Areas:
  • Aphasia: Difficulty with language.
  • Broca’s Area: Located in the frontal lobe. Damage here means a person can understand language but cannot express it (unable to form words).
  • Wernicke’s Area: Located in the temporal lobe. Damage here means a person can speak, but the speech is meaningless, and they cannot understand the words of others or writing.
• Lateralization: The hemispheres are separated by the Corpus Callosum (a bundle of axons). The Left hemisphere is analytical and handles language/speech. The Right hemisphere handles inference, holistic thought, and emotion perception/expression.
• Neuroplasticity: The brain's ability to modify itself after damage. Neurons reorganize, and other areas compensate for the loss. Plasticity is highest in childhood.

Brain Scanning Techniques

• EEG (Electroencephalogram): Electrodes on the scalp measure electrical brain waves.
• CT / CAT Scan (Computerized Axial Tomography): X-rays taken around the brain combined into a composite image of structure.
• MRI (Magnetic Resonance Imaging): Uses magnetic fields on atoms to produce a detailed image of brain structure.
• fMRI (Functional MRI): Continuous scanning that shows how activity/blood flow moves around the brain during tasks.
• PET (Positron Emission Tomography): Radioactive glucose is injected; the scan measures where the glucose is consumed in the brain to track activity.

Consciousness: Awareness and Rhythms

• Definition: Consciousness is an awareness of ourselves and our environment. It exists in different levels (e.g., alert, daydreaming, deep sleep).
• Selective Attention: We focus conscious awareness on specific things. This can lead to inattentional blindness, which is failing to see visible objects when attention is focused elsewhere.
• Circadian Rhythm: A $24$ hour biological clock. It influences body temperature (highest in the morning, lowest at night).
  • Regulation: Bright light activates proteins in the retina, which signals the hypothalamus to decrease production of melatonin (the sleep-inducing hormone).

The Stages and Functions of Sleep

• Sleep Cycle: Cycles last approximately $90$ minutes. Before sleep, while awake and relaxed, the brain shows alpha waves.
• Stage 1: Features slow breathing and theta brain waves. Individuals may experience fantastic sensations or jolting awake.
• Stage 2: Characterized by sleep spindles (bursts of activity) and K-complexes (spikes in brain waves).
• Stage 3 (and 4): The "Deep Sleep" stage. Features large, slow delta waves. Involved in restoration. Heart rate and breathing are at their slowest. This is when bedwetting, sleepwalking, and night terrors occur. Stage 4 eventually disappears as the night progresses.
• REM (Rapid Eye Movement): The brain shows rapid waves similar to Stage 1. Heart rate rises and breathing becomes rapid.
  • Muscle Paralysis: The brainstem blocks messages from the motor cortex so the body does not act out dreams.
  • Vivid Dreams: Occur during this stage. REM periods become longer as the night goes on.
• Why We Sleep: To boost the immune system, improve mood, increase cognition/memory, restore/repair brain tissue, and release growth hormones.

Dreams and Hypnosis

• Dream Theories:
  • Psychoanalytic (Freud): Dreams have Manifest Content (the literal story) and Latent Content (the hidden meaning/unconscious wishes).
  • Physiological Function: Dreams keep the brain stimulated and strengthen neural networks.
  • Activation-Synthesis: Dreams are the brain's attempt to make sense of random neural activity in the occipital lobe and limbic system during REM.
  • Information Processing: Dreams help organize and consolidate memories. Brain areas active during the day are reactivated during REM.
• Hypnosis: A social interaction where a hypnotist suggests that certain perceptions/behaviors will occur.
  • Social Influence Theory: Subjects are imaginative actors playing a social role.
  • Divided Consciousness Theory: Hypnosis involves a state of dissociation or divided consciousness.

Human Development: Cognitive Theories

• Nature vs. Nurture: Explored through Twin Studies and Epigenetics (how environment influences gene expression without changing the DNA sequence).
• Jean Piaget's Stages of Cognitive Development:
  1. Sensorimotor (Birth to $2$ years): Experiencing the world through senses/movement. Milestone: Object Permanence (at $8$ months).
  2. Preoperational ($2$ to $6$ years): Language development but unable to perform mental operations. Characterized by Egocentrism and a lack of knowledge regarding Conservation (volume/mass remains same despite shape change).
  3. Concrete Operational ($7$ to $11$ years): Can perform concrete mental operations and conservation tasks. Cannot think abstractly.
  4. Formal Operational ($12+$ years): Development of abstract thinking, systematic reasoning, and logic.
• Vygotsky's Sociocultural Theory:
  • Zone of Proximal Development ($ZPD$): The difference between what a child can do alone vs. with help.
  • Scaffolding: Teachers provide a varying level of assistance based on the child's needs.
  • Speech: Social speech leads to Private speech (talking to self during tasks), which leads to Inner speech (thought).

Moral and Psychosocial Development

• Lawrence Kohlberg's Moral Levels (Based on reactions to the Heinz Dilemma):
  1. Preconventional: Focus on self-interest and avoiding punishment (Obedience vs. Instrumental orientations).
  2. Conventional: Upholding laws and social rules (Interpersonal norms and Social System morality).
  3. Postconventional: Following a self-defined ethical code or universal principles (Social Contract and Universal Ethical Principles).
• Erik Erikson's Psychosocial Stages:
  • Infancy: Trust vs. Mistrust (Virtue: Hope).
  • Toddlerhood: Autonomy vs. Shame/Doubt (Virtue: Will).
  • Preschooler: Initiative vs. Guilt (Virtue: Purpose).
  • Elementary: Industry vs. Inferiority (Virtue: Competency).
  • Adolescence: Identity vs. Role Confusion (Virtue: Fidelity).
  • Young Adulthood: Intimacy vs. Isolation (Virtue: Love).
  • Middle Adulthood: Generativity vs. Stagnation (Virtue: Care).
  • Late Adulthood: Integrity vs. Despair (Virtue: Wisdom).

Questions & Discussion

• Psychology Today Dream Survey Results ($n > 1000$):
  • $95\%$ remember some dreams.
  • $68\%$ have recurring dreams.
  • $39\%$ claim to be able to control dreams.
  • $28\%$ have died in a dream.
  • Most common themes: falling or being chased. External stimuli (sounds/smells) often enter dreams.
• Case Studies on Erikson's Stages:
  • Case 1: Rosemary feels mostly satisfied with raising her family despite not going to college. Stage: Integrity vs. Despair.
  • Case 2: Timmy wants to carry his own cereal; his mom allows him even when he spills. Stage: Autonomy vs. Shame and Doubt.
  • Case 3: Baby Christopher is fed every $3-4$ hours and is comforted when fussy. Stage: Trust vs. Mistrust.
  • Case 4: Samuel is tired of casual dating and wants one special person to settle down with. Stage: Intimacy vs. Isolation.