Behavioral Genetics and Nervous System - Vocabulary Flashcards

Behavioral Genetics

• Nature vs. Nurture Debate

  • Behavioral geneticists study the contribution of genetic factors vs. environmental factors
  • Focus on parsing out how much of human variability is due to:
  • Heritability: genetic contribution to characteristics
  • Environment: experiences, upbringing, stimulation

• Key Misconceptions

  • Important: Genetic predispositions are NOT deterministic - you are not "doomed" by your genes
  • Example: IQ inheritance
  • 50\% genetic contribution
  • 50\% environmental factors (intellectual stimulation, reading, puzzles, educational exposure)

• Types of Genetic Transmission

  1. Monogenic Transmission
  • Mono = one gene
  • Single gene determines trait or disorder
  • Example: Huntington's disease
  • Very rare occurrence
  1. Polygenic Transmission
  • Poly = multiple genes
  • Most traits are polygenic
  • Multiple genes work together to create characteristics
  • Examples:
    • Schizophrenia
    • Height, weight, hair color
    • Personality traits
    • Intelligence

• Research Methods

  • Twin Studies
  • Used to determine heritability percentages
  • Compare twins raised together vs. separated at birth
  • Types of Twins:
  • Monozygotic (identical): <1% of population, same sex, identical physical features
  • Dizygotic (fraternal): different physical characteristics possible
  • Famous Case Study: Jim Springer & Jim Lewis
  • Identical twins separated at birth findings:
    • Both exactly 6\ {\text{feet tall}}, 180\ {\text{pounds}}
    • Same interests: math, carpentry
    • Both hated spelling
    • Both had dogs named "Toy"
    • Both married women named Linda, divorced, remarried women named Betty
    • Both had sons named James Allen

• Epigenetics

  • Definition: Environment and biology constantly interact; environment can change genetic expression
  • Key Points:
  • Having a gene doesn't guarantee it will activate
  • Environment determines gene activation/deactivation
  • Doesn't change chromosome structure
  • Example: Depression gene may remain dormant until major life stressor triggers activation

The Nervous System

• Overview

  • Body's communication network
  • Processes sensory input and coordinates responses
  • Example: Touching flame → sensory input spinal cord brain motor response

• Major Divisions

  1. Peripheral Nervous System (PNS)
  • Definition: Everything except brain and spine (muscles, organs, glands, skin receptors)
  • A. Somatic Nervous System
    • Voluntary muscle movements
    • Conscious, deliberate actions
    • Example: Opening a door, lifting hand from flame
  • B. Autonomic Nervous System
    • Involuntary muscle movements
    • Automatic bodily functions
    • Two Subdivisions:
      • Sympathetic Nervous System:
      • Arousing/activating
      • Fight-or-flight response
      • Example: Bear encounter
        • heart racing, sweating, dilated pupils, blood flow to muscles
      • Parasympathetic Nervous System:
      • Relaxing/restoring
      • Returns body to homeostasis
      • Memory trick: "Para" = paralysis/calming down
      • Example: After escaping bear heart rate normalizes, breathing slows
  1. Central Nervous System (CNS)
  • Components: Brain and spine
  • Spinal Cord Functions:
    • Communication relay between sensory input and motor output
    • Reflex control: Knee-jerk reactions that bypass the brain
  • Acts as "middle man" between environment and brain

• Neurons: The Communication Units

  • Types of Neurons
  1. Sensory Neurons
     • Carry information from sense organs TO brain
     • Handle touch, smell, sight, hearing, taste
  2. Interneurons
     • "Middle man" neurons
     • Connect sensory to motor neurons
     • Each neuron connects to ~15{,}000 others
  3. Motor Neurons
     • Carry movement orders from brain TO muscles
     • Execute behavioral responses
  4. Glial Cells
     • Support neurons by providing nutrients
     • Clean up toxins
     • Maintain neuron vitality
     • Note: Deficiency linked to schizophrenia development

• Neuron Structure

  • A. Soma (Cell Body)
    • Keeps cell alive
    • Contains vital structures
    • Nucleus: Contains DNA/genetic material with neuron instructions
  • B. Dendrites
    • Finger-like projections from soma
    • Function: Receive neurotransmitters
    • (norepinephrine, dopamine, serotonin, acetylcholine)
    • Act like "antennas" for incoming information
  • C. Axon
    • Carries neurotransmitters away from cell body
    • Transmits electrical impulses
    • Example: Norepinephrine (used in Adderall for ADHD treatment)
  • D. Myelin Sheath
    • Fatty tissue insulation around axon
    • Functions:
    • Protects the axon
    • Increases speed and efficiency of transmission
  • E. Terminal Buttons/Axon Terminals
    • Located at end of axon
    • Release neurotransmitters into synaptic cleft

• Action Potential Process

  • The Electrical Process
  • 1. Resting Potential
  • Neuron at rest: -70\ \text{mV}
  • No neurotransmitter activity
  • Negative charge inside membrane.
  • 2. Depolarization (Action Potential)
  • Sodium channels open
  • Na^{+} rushes into the membrane
  • Charge increases from -70\ \text{mV} to +40\ \text{mV}
  • Becomes more positive
  • 3. Repolarization
  • (Details of this step are not provided in the transcript beyond the heading)