1. This is your brain

• Professor Paul Bloom: 'We're going to begin the class proper, Introduction to Psychology, with a discussion about the brain.'
• The Astonishing Hypothesis


  You, your joys and your sorrows, your memories and your ambitions, your sense of personal identity and free will are in fact no more than the behavior of a vast assembly of nerve cells and their associated molecules
• Dualism


  The doctrine that humans possess physical material bodies, but also immaterial souls that possess, reside in, and connect to those physical bodies
• Descartes' arguments for dualism

  • Observation of human actions - humans can do things machines cannot
  • Method of doubt - Descartes could not doubt that he was thinking
• Dualism is common sense and enmeshed in our language and intuitions
• Fictional examples of personal identity surviving radical bodily changes


  • A teenager waking up as Jennifer Garner
  • A man dying and being reborn into a child's body
  • Gregor Samsa waking up as a giant insect
  • Odysseus' companions transformed into pigs
• Many people believe multiple personalities can occupy a single body
• Most people around the world believe people can survive the destruction of their physical bodies
• The scientific consensus is that dualism is wrong - the mind is what the brain does
• Problems with dualism


  • It is unscientific and fails to explain many aspects of mental life
  • It struggles to explain the connection between physical body and immaterial soul
  • We now know physical objects can do complicated things previously thought impossible
• There is strong evidence the brain is involved in mental life
• The brain does not look impressive - it is just a "disgusting" lump of "old meat loaf"
• The goal of neuroscience is to explain how the brain can give rise to thought and consciousness
• Like an old meat loaf, the brain is gray when you take it out of the head, but inside the head it's bright red because it's pulsing with blood. It doesn't even taste good.
• Everything's good with cream sauce.
• The question is, "How can something like the brain give rise to us?"
• The goal of neuroscience is to explain how the brain works and how the brain can give rise to thought.
• Neuron


  The basic unit of the brain, with three major parts: dendrites, cell body, and axon
• There are about one thousand billion neurons in the brain, and each neuron can be connected to around thousands, perhaps tens of thousands, other neurons.
• Types of neurons


  • Sensory neurons
  • Motor neurons
  • Interneurons
• Neurons either fire or they don't - it's an all or nothing process.
• Intensity coding


  Can be done by the number of neurons firing or the frequency of firing
• Synapse


  The tiny gap between the axon of one neuron and the dendrite of another, where neurotransmitters are released
• Neurotransmitters


  Chemicals that can have excitatory or inhibitory effects on other neurons
• Agonists


  Drugs that increase the effect of neurotransmitters
• Antagonists


  Drugs that decrease the effect of neurotransmitters
• The brain is highly resistant to damage and can have different parts take over functions of damaged areas.
• The brain uses parallel processing, unlike a computer which uses serial processing, allowing it to be extremely fast despite using slow tissue.
• There is no machine yet that can do anything as well as a 2-year-old human, because the human brain is far more complicated than any simple neural network.
• Some basic functions like sucking, limb withdrawal, erection, and vomiting can occur without the brain.
• Subcortical structures


  • Medulla (controls heart rate and respiration)
  • Cerebellum (controls balance and coordination)
  • Hypothalamus (controls feeding, hunger, thirst, and sleep)
• The cortex is the outer layer of the brain where the most interesting psychological processes take place. It makes up 80% of the brain's volume.
• Lobes of the cortex

  • Frontal lobe
  • Parietal lobe
  • Occipital lobe
  • Temporal lobe
• The cortex is the outer layer and the outer layer is all crumpled up
• If you took out somebody's cortex and flattened it out, it would be two feet square, sort of like a rug
• The cortex is where all the neat stuff takes place
• Fish don't have much of a mental life, reptiles and birds have a little bit, primates have a lot, and humans have a real lot
• Eighty percent of the volume of our brain is cortex
• The lobes of the cortex

  • Frontal lobe
  • Parietal lobe
  • Occipital lobe
  • Temporal lobe
• The left and right halves of the brain are duplicated with some slight and subtle differences