Chapter 25 Outline

  • Eric Kandel

    • Aplysia: studied memory through Aplysia

    • Non-Associative Memory and Synaptic Strength: habituation and sensitization were accompanied by changes in the strength of synaptic transmission between sensory neurons and motor neurons

  • Habituation of Aplysia Gill-Withdrawal Reflex

    • Experiment: continuously touching the siphon of the Aplysia decreases the gill-withdrawal reflex

    • Motor Neuron: habituation results in decreased activation of the motor neuron

    • Sensory Neuron: habituation does not change activation in sensory neuron

    • Synaptic Connections: inactivation decreases as a result of long-term habituation

  • Anatomy of the Hippocampus

    • Neural Circuit: entorhinal cortex → dentate gyrus → CA3 → CA1

  • AMPA & NMDA Receptors

    • AMPA: glutamate receptor, influx of sodium, depolarizes postsynaptic neuron

    • NMDA: glutamate receptor, influx of calcium, magnesium block removed (with AMPA depolarization)

  • Receptor Phosphorylation and Trafficking

    • Protein Kinases: a rise in calcium activates two protein kinases (PKC & CaMKII) that phosphorylate proteins

    • AMPA Trafficking: more AMPA receptors are brought to the synapse

  • LTP vs. LTD

    • LTP: rise in calcium → activation of protein kinase → phosphorylated synaptic protein yields LTP

    • LTD: decreased calcium → activation of protein phosphatase → unphosphorylated synaptic protein yields LTD

  • Importance of LTP/LTD in Memory

    • Inhibitory Avoidance Experiment: a rat associates a dark side of a box with a foot shock (LTP)

      • LTD: exposing animals to the dark side without the foot shock causes LTD instead

  • Protein Synthesis

    • Protein Synthesis: occurs during the period of memory consolidation

    • Protein Synthesis Inhibitors: cause deficits in learning and memory