MCAT Behavioral Science: Biology and Behavior (Chapter 1)

May 28, 2024

MCAT Behavioral Science: Biology and Behavior (Chapter 1)

Overview

  • Chapter Title: Biology and Behavior
  • Based on: Kaplan book
  • Objectives:
    1. History of Neuropsychology
    2. Organization of the Human Nervous System
    3. Organization of the Brain
    4. Focus on the Forebrain
    5. Influences on Behavior
    6. Development Process

Objective 1: History of Neuropsychology

  • 19th Century: Shift from philosophical to empirical/scientific study of behavior.
  • Key Figures:*
    • Franz Gall (1758-1828): Developed phrenology; debunked but spurred research.
    • Pierre Flourens: Studied brain functions via extirpation in animals; found specific brain parts had specific functions.
    • William James: Father of American psychology, pioneered functionalism.
    • John Dewey: Criticized reflex arc, advocated for studying the organism as a whole.
    • Paul Broca: Linked specific functional impairments to specific brain lesions; discovered Broca’s area.
    • Hermann von Helmholtz: Measured speed of nerve impulses; helped transition psychology to natural sciences.
    • Sir Charles Sherrington: Inferred existence of synapses; believed synaptic transmission was electrical, but it's chemical.

Objective 2: Organization of the Human Nervous System

  • Nerve Cell Types:

    • Sensory Neurons (Afferent): Transmit sensory info to brain/spinal cord.
    • Motor Neurons (Efferent): Transmit motor info to muscles/glands.
    • Interneurons: Most numerous; link neurons, often involved in reflexive behavior.
  • Example: Stepping on a Lego—reflexive arc (interneurons in spinal cord) causes immediate reaction before brain processes pain.

  • Nervous System Divisions:

    • Central Nervous System (CNS): Brain and spinal cord.
    • Peripheral Nervous System (PNS): Nerve tissue and fibers outside CNS; includes 31 spinal and 10 of 12 cranial nerve pairs.
      • Somatic Nervous System: Sensory and motor neurons in skin, joints, muscles.
      • Autonomic Nervous System (ANS): Regulates involuntary functions (heartbeat, respiration, digestion, etc.).
        • Sympathetic Nervous System: Fight or flight; increases heart rate, dilates pupils, inhibits digestion, etc.
        • Parasympathetic Nervous System: Rest and digest; reduces heart rate, constricts bronchi, stimulates digestion, etc.

Objective 3: Organization of the Brain

  • Brain Divisions: Hindbrain, midbrain, forebrain.
  • Meninges: Protective connective tissue covering the brain.
    • Layers: Dura mater, arachnoid mater, pia mater.
    • Cerebrospinal Fluid: Cushions the brain, produced in ventricles.
  • Functional Correlation: Basic survival functions = base of the brain; complex functions = higher regions.

Hindbrain (Rhombencephalon)

  • Functions: Vital processes (breathing, digestion, motor coordination).
  • Divisions during Development:
    • Myelencephalon: Forms medulla oblongata (vital functions).
    • Metencephalon: Forms pons (sensory/motor pathways) and cerebellum (posture, balance, movement).

Midbrain (Mesencephalon)

  • Functions: Sensory/motor information, involuntary reflexes.
  • Key Structures:
    • Superior Colliculi: Visual input.
    • Inferior Colliculi: Auditory input.

Forebrain (Prosencephalon)

  • Functions: Complex behaviors, emotion, memory.
  • Divisions during Development:
    • Telencephalon: Cerebral cortex, basal ganglia, limbic system.
    • Diencephalon: Thalamus, hypothalamus, posterior pituitary, pineal gland.

Methods of Mapping the Brain

  • Lesion Studies: Study impaired brain regions in animals/humans.
  • Electrical Stimulation: Create cortical maps, stimulate deeper brain regions (study corresponding responses).
  • Recording Brain Activity:
    • Electrodes: Record electrical activity in individual neurons.
    • EEG: Noninvasive, records electrical patterns, widely used in sleep, seizure studies.

Next Steps

  • Upcoming: Detailed exploration of the forebrain (Chapter 1, Objective 4).