P101Phelps2024chap 3.3s

Psychology 101 Chapter 3: Biology and Behaviour

Lecture Overview

  • Genetic basis of Psychological Science

    • Study Question: How and why are twins used to study psychological science?

    • Key Topics Covered:

      • Subcortical structures: The limbic system, brainstem, cerebellum

      • Neuroplasticity and Neurogenesis

      • Genetics and behaviour

      • Heredity and genetic modification

Structure and Organization of the Nervous System

  • Subcortical Structures: The Limbic System

    • Basal Ganglia

      • Involved in planned movement

      • Related disorders: Parkinson’s, Huntington’s, Tourette’s

    • Nucleus Accumbens

      • Part of the reward system

    • The Thalamus

      • Functions as a sensory relay station

Further Subcortical Structures

  • Hypothalamus

    • Controls endocrine system functions

    • Regulates:

      • Hunger and thirst

      • Sexual behaviour

      • Body temperature

      • Blood pressure

      • Sleep/wake cycle

  • Hippocampus

    • Critical for learning and memory

    • Essential for forming new memories

  • Amygdala

    • Recognizes emotional significance

    • Mediates the fear response

Brainstem and Cerebellum

  • Brainstem

    • Medulla & Pons

      • Vital for reflexes, posture, and rhythm

      • Involved in the sleep-wake cycle via the reticular formation

    • Midbrain

      • Contains inferior and superior colliculus involved in orienting reflexes

        • Inferior: auditory attention

        • Superior: visual attention

      • Contains substantia nigra, responsible for dopamine production

    • Cerebellum

      • Coordinates balance and timing of movements

      • Plays a role in attention and cognitive aspects of emotion

Brain-Body Communication

  • Divisions of the Nervous System

    • Peripheral Nervous System

      • Autonomic Nervous System

        • Regulates the activity of organs and glands

        • Sympathetic Nervous System: Fight-or-flight response

        • Parasympathetic Nervous System: Returns body to baseline, maintains homeostasis

Hormones and Behaviour

  • Hormones

    • Functions similarly to neurotransmitters, using the blood system

    • Secreted by endocrine cells and neurons

  • Types of Hormones

    • Peptides: Neurohormones and those from the pituitary

    • Steroids: From adrenal glands and gonads

  • Sex Hormones

    • Males: Higher Androgens (Testosterone)

    • Females: Higher Estrogens (Estradiol and Progesterone)

Neurogenesis and Neuroplasticity

  • Neurogenesis

    • Formation of new neurons, starting from stem cells

    • Example: Maguire's study on London cab drivers found increases in hippocampal size linked to navigation skills

  • Neuroplasticity

    • Brain's ability to change and rewire based on experiences

    • Hebb's principle: "Cells that fire together, wire together"

Genetic Basis of Psychological Science

  • Genes and Development

    • Genes: Segments of DNA organized into chromosomes

      • Humans have 23 pairs

    • Genotype vs. Phenotype

      • Genotype: Genetic constitution

      • Phenotype: Observable traits from genetics and environment

Mendelian Genetics

  • Alleles

    • Genes exist in pairs (homozygous vs. heterozygous)

    • Dominant Gene: Expressed when alleles differ

    • Recessive Gene: Expressed only when paired with the same gene

    • Example: Mendel's experiments with smooth vs. wrinkled seeds

Environmental Influence on Genes

  • The environment determines gene expression—e.g. Buckeye butterfly development

  • Human Genome Project: Identifying components of the human genome

  • Behavioural Genomics: Studies relationship between genes and behaviour, relevant to psychological disorders

Behavioural Genetics: Twin Studies

  • Monozygotic vs. Dizygotic Twins

    • Identical twins (same genotype) vs. fraternal twins (50% share genes)

  • Adoption Studies

    • Compare adopted siblings with biological siblings and twins reared differently

  • Heritability: Proportion of variability in traits due to genetic variation

    • Intelligence heritability: MZ twins (75%) vs. DZ twins (50%)

Gene Expression and Behaviour

  • Not all genes are active; about 6000-7000 are expressed in the brain

  • Epigenetics: Changes in gene expression due to experience without altering the genetic code

    • Example: Effects of maltreatment on behaviour through gene expression

  • Optogenetics: Genetic modifications allowing control of neuron activity with light

Next Class Preparation

  • Moodle Midterm Information

    • 40-50 Multiple choice questions

    • Matching questions (with definitions and terms)

    • Two or three study questions (answered briefly but effectively)