Chapter 2: The Biology of Mind - Study Notes

Chapter 2: The Biology of Mind

Surveying the Chapter: Overview

  • What We Have in Mind
    • Building blocks of the mind: Neurons and how they communicate using neurotransmitters.
    • Systems that build the mind: Functions of the different parts of the nervous system.
    • Supporting player: The slower-communicating endocrine system (involves hormones).
    • Star of the show: The brain and its structures.
    • Searching for the self by studying the body.

Phrenology

  • Phrenology:
    • Developed by Franz Gall in the early 1800s.
    • Main idea: Localization of function – the study of bumps on the skull and their relation to mental abilities and traits.

Neurons and Neuronal Communication

Structure of a Neuron
  • There are billions of neurons (nerve cells) throughout the body.
  • Functions of neurons:
    • Receives signals from other neurons; some signals prompt it to fire, while others inhibit firing.
    • When the threshold is reached, the action potential initiates its movement.
    • The firing action is compared to a gun: it either fires or it does not.
    • This firing response is known as the “all-or-nothing” response.
    • The action potential travels down the axon from the cell body to the terminal branches.
    • The signal then must cross a gap called a synapse to transmit the message to another cell.
Neural Communication
  • When does the cell send the action potential?
    • It sends it when it reaches a threshold level of stimulation.

Some Neurotransmitters and Their Functions

  • Neurotransmitter Functions:
    • Serotonin:
      • Function: Affects mood, hunger, sleep, and arousal.
      • Problems: Undersupply linked to depression; some antidepressant drugs raise serotonin levels.
    • Dopamine:
      • Function: Influences movement, learning, attention, and emotion.
      • Problems: Oversupply linked to schizophrenia; undersupply linked to tremors and decreased mobility in Parkinson’s disease and ADHD.
    • Acetylcholine (ACh):
      • Function: Enables muscle action, learning, and memory.
      • Problems: ACh-producing neurons deteriorate as Alzheimer’s disease progresses.
    • Norepinephrine:
      • Function: Helps control alertness and arousal.
      • Problems: Undersupply can depress mood and cause ADHD-like attention problems.
    • Gamma-Aminobutyric Acid (GABA):
      • Function: A major inhibitory neurotransmitter.
      • Problems: Undersupply linked to seizures, tremors, and insomnia.
    • Glutamate:
      • Function: A major excitatory neurotransmitter involved in memory.
      • Problems: Oversupply can overstimulate the brain, leading to migraines or seizures; thus some avoid MSG (monosodium glutamate) in food.

More Parts of the Nervous System

  • The Endocrine System:
    • A set of glands that produce chemical messengers known as hormones.

How We Study The Brain Today

  • Tools to Read Brain Activity:
    • EEG (Electroencephalogram): Measures electrical activity in the brain.
    • MRI (Magnetic Resonance Imaging): Provides detailed images of brain structures.
    • fMRI (Functional MRI): Measures brain activity by detecting changes associated with blood flow.
    • PET (Positron Emission Tomography): Uses radioactive tracers to visualize brain function.
Areas of the Brain and Their Functions
  • Brainstem and Cerebellum:
    • Function: Governs nonverbal learning, memory, motor functions, equilibrium, and posture.
  • Limbic System:
    • Function: Manages emotions, memory, motivation, and connects thoughts to bodily functions.
  • Cortex (Outer Covering):
    • Function: Processes information related to thought, memory, attention, language, and consciousness.

The Lobes of the Cerebral Cortex

  • Frontal Lobes:
    • Function: Involved in speaking, muscle movements, planning, and judgments.
  • Parietal Lobes:
    • Function: Includes the sensory cortex and processes perception.
  • Occipital Lobes:
    • Function: Receives visual information from the opposite visual field.
  • Temporal Lobes:
    • Function: Involved in auditory processing and smell/taste recognition.
Case Study of Hemispherectomy
  • A 6-year-old had a hemispherectomy to end life-threatening seizures; the remaining hemisphere compensated for the damage, highlighting brain plasticity.

Plasticity: The Brain is Adaptable

  • If the brain is damaged:
    • It does not repair damaged neurons.
    • However, it can restore some functions by forming new connections, reassigning existing networks, and inserting new neurons, some grown from stem cells.

Language and Hemispheric Differences

  • Details vs. Big Picture:
    • Details:
      • Language: Words/definitions, linear and literal details, calculations.
    • Big Picture:
      • Language: Tone/inflection, associations, feelings.
  • Hemispheric Differences:
    • Left Hemisphere vs. Right Hemisphere: Distinct roles in processing various types of information, such as language and emotions.