PSYC230 Chapter 2: Intro to Neuroscience

• Neuron


  Cells specialized to create, receive, and transmit information in the nervous system

  
• Neurons

  • Are not physically connected
  • Come in many different types varying in shape, size, connections, etc.
• Main parts of a neuron

  • Cell body (Soma)
  • Dendrites
  • Axon
• Dendrites


  Multiple branches reaching from the cell body, which receive information from other neurons
• Axon


  Tube filled with fluid that transmits electrical signal to other neurons
• How information is transferred in the nervous system

  1. Neurons receive a signal that is in either a physical form or a chemical form

  2. Sodium diffuses down through the dendrites and cell body

  3. The electrical signal is activated and travels quickly down the axon to the axon terminals

  4. This causes the release of neurotransmitters at the synapse and the process starts all over in the next neuron
• Action potential


  A process that only occurs in axons, where neuron receives signal from environment and information travels down the axon of that neuron to the dendrites of another neuron

  
• Resting potential


  Inside of neuron is more negative than the outside, due to abundance of Sodium outside and abundance of Potassium inside
• Steps in an action potential

  1. Sodium channels open, sodium rushes into the cell

  2. Potassium Channels begin to open, Potassium leaves the cell

  3. The axon is then returned to its resting potential, the ion pump restores the normal distribution of NA+ and K+ ions
• Myelin


  An insulating layer, or sheath that forms around nerves, including those in the brain and spinal cord
• All or none law

  Action potential either happens or it doesn't, no strength or speed of action potential
• Synapse


  Space between axon of one neuron and dendrite or cell body of another, where neurotransmitters cross and bind with the receiving dendrites
• Principle of neural representation


  Everything a person experiences is based on representations in the person's nervous system
• Feature detectors


  Neurons that respond best to a specific stimulus
• Sensory coding

  • Specificity coding: representation of a stimulus by the firing of specifically tuned neurons
  • Population coding: representation of a stimulus by the pattern of firing of a large number of neurons
  • Sparse coding: representation of a stimulus by a pattern of firing of only a small group of neurons, with the majority of neurons remaining silent