Chapter 3 - Biopsychology

Biopsychology Overview

• Biopsychology: Examines the biological basis of behavior, thoughts, and actions.

Human Genetics

Genetics Fundamentals

• Genetics: The science of inherited traits.

• DNA: Molecule containing an organism's genetic material.

• Gene: A section of DNA with a specific sequence that controls visible traits.

• Chromosomes: Tightly wound strands of DNA; humans have 46 (23 from each parent).

• Allele: A specific version of a gene (e.g., hair color).

• Dominant Gene: Actively controls the expression of a trait.

• Recessive Gene: Influences trait expression only when paired with an identical gene.

Genotype vs Phenotype

• Genotype: A person's genetic makeup inherited from their parents.

• Phenotype: Physical characteristics resulting from the genotype.

• Homozygous: Two copies of the same allele (e.g., BB).

• Heterozygous: A combination of different alleles (e.g., Bb).

Range of Reaction and Gene-Environment Interaction

• Range of Reaction: Genes set boundaries for potential development; environment shapes actual expression.

• Genetic Environmental Correlation: Genes impact environment, which in turn affects how genes are expressed (e.g., athletes influenced by their environment).

Epigenetics

• Epigenetics: Study of how the same genotype can result in different phenotypes.

• Identical twins (same genetic makeup) may exhibit different phenotypes.

• Link to Behavior: Genetics are linked to various traits and psychological disorders.

Nervous System

Biological Perspective and Neuroscience

• Biopsychology: Focuses on cellular and chemical processes underlying behavior.

• Neuroscience: Studies the structure and function of the brain and nervous system.

Structure of the Neuron

• Neuron: Specialized cell transmitting messages in the nervous system.

• Parts of a Neuron:

  • Dendrites: Receive messages from other neurons.

  • Soma (Cell Body): Contains the nucleus and supports the cell.

  • Axon: Tube that carries neural messages away from the soma.

  • Axon Terminals: Knobs that communicate signals to other cells.

  • Myelin Sheath: Insulates the axon to speed up signal transmission.

• Nerves: Bundles of axons.

Glial Cells

• Glial Cells: Support neurons by providing nutrients, producing myelin, and aiding in waste cleanup.

• Number of glial cells to neurons is approximately 10 to 1.

Neural Communication

Ionic Activity

• Neurons have positively and negatively charged ions.

• Resting Potential: Neuron is ready to fire; negative inside, positive outside.

• Action Potential: Neural impulse generated by ion exchange.

• The process is all-or-none—a neuron either fires completely or does not at all.

Synaptic Transmission

• Synapse: Gap between neurons for communication.

• Neurotransmitters: Chemicals that relay signals across the synapse.

  • Excitatory Synapse: Encourages the receiving cell to fire.

  • Inhibitory Synapse: Prevents firing of the receiving cell.

  • Receptor Sites: Locations on dendrites or muscle cells where neurotransmitters attach.

Neurotransmitter Effects

• Agonists: Mimic neurotransmitters and enhance their effects (e.g., drugs for Parkinson’s).

• Antagonists: Block neurotransmitter activity (e.g., antipsychotics).

Types of Neurotransmitters

• Acetylcholine (ACh): Involved in arousal and muscle control (excitatory/inhibitory).

• Norepinephrine (NE): Affects arousal and mood (excitatory).

• Dopamine (DA): Important for movement and pleasure (excitatory/inhibitory).

• Serotonin (5-HT): Influences mood and sleep (excitatory/inhibitory).

• Gamma-aminobutyric acid (GABA): Inhibitory neurotransmitter (inhibits movement).

• Glutamate: Important for learning and memory (excitatory).

• Endorphins: Neurotransmitters involved in pain relief (inhibitory).

Central Nervous System (CNS)

• Comprised of the brain and spinal cord, regulating life-sustaining functions and thoughts.

Brain Components

• Regions of the Brain: Different areas handle distinct functions, cognition, and memory.

• Spinal Cord: Connects brain to body, allowing fast reflex actions.

Neuroplasticity and Neurogenesis

• Neuroplasticity: The brain's ability to change structure/function based on experience.

• Neurogenesis: Formation of new neurons, often during prenatal development.

Peripheral Nervous System (PNS)

• Comprises nerves outside the CNS; communicates with sensory systems and controls muscles.

• Divided into two main systems:

  • Somatic Nervous System: Controls voluntary muscles and sensory information relay.

  • Autonomic Nervous System: Controls involuntary muscles, organs, and glands.

    • Subdivisions:

      • Sympathetic Nervous System: Activates the fight-or-flight response.

      • Parasympathetic Nervous System: Restores routine functions.

Endocrine System

Overview

• Composed of glands that secrete hormones, which are chemical messengers influencing bodily functions.

Major Endocrine Glands

• Pituitary Gland: Master gland regulating other glands; important for growth hormone secretion.

• Pineal Gland: Regulates sleep-wake cycles through melatonin.

• Thyroid Gland: Controls metabolism and growth.

• Pancreas: Manages blood sugar levels via insulin and glucagon.

• Gonads: Governs sexual development and behavior (ovaries/testes).

• Adrenal Glands: Secret hormones for stress response and salt regulation.

Brain Imaging Techniques

• CT Scan: X-ray imaging of the brain for abnormalities.

• MRI: Produces detailed images of brain structures using radio waves.

• EEG: Records electrical activity to evaluate brain function.

• PET Scan: Shows active brain regions via blood flow measurement.

• fMRI: Tracks brain activity over time by monitoring blood oxygen levels.

Brain Structure

Hindbrain

• Medulla: Controls automatic functions like breathing and heart rate.

• Pons: Relays information and regulates sleep and coordination.

• Cerebellum: Coordinates motor movement and may contribute to cognitive functions.

Midbrain

• Regulates sleep/wake cycles and motor activity.

• Substantia Nigra & Ventral Tegmental Area: Dopamine-producing areas critical for movement.

Forebrain

• Limbic System: Involved in emotion and memory (includes thalamus, hippocampus, amygdala).

• Cerebral Cortex: Responsible for higher-level thinking and sensory processing.

• Cerebral Hemispheres: Divided into left and right sides, controlling opposite body sides.

Association Areas

• Broca’s Area: Language production; located in the left frontal lobe.

• Wernicke’s Area: Language comprehension; located in the left temporal lobe.

Summary of Brain Lobes

• Frontal, Parietal, Occipital, Temporal Lobes: Each responsible for distinct cognitive and sensory functions.