PSY-220 Study Guide - Final Guide: Brain-Derived Neurotrophic Factor
1 May 2018
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Long Term Potentiation
LTP: one or more axons connected to a dendrite bombard it with rapid series of stimuli
o Leaves the synapse “potentiated” for a period of time
o The neuron is more responsive to input of the same type
o Occurs in Post Synaptic Neurons
Three Properties of LTP that make it attractive for Learning and Memory:
• Specificity: only synapses onto cells that have been highly active and they become
strengthened
• Cooperativity: simultaneous stimulation by two or more axons produces LTP much
more strongly than does repeated stimulation by a single axon
• Associativity: pairing a weak input with a strong input enhances later responses to a
weak input
Biochemical Mechanisms of LTP: changes at glutamate synapses
▪ Two types of glutamate receptors:
o AMPA receptors: excited by the neurotransmitter glutamate, but it can also
respond to a drug called AMPA
▪ Opens SODIUM channels
o NMDA receptors: excited by the neurotransmitter glutamate, but it can also
respond to a drug called NMDA
▪ Sodium and Calcium enter through NDMA channels
▪ BUT ONLY after magnesium has been removed
▪ BOTH ARE IONOTROPIC RECEPTORS when stimulated they open a channel to
let ions enter the post synaptic cell
The LTP Process in Hippocampal Neurons
• Repeated glutamate excitation of AMPA receptors depolarizes the membrane
o Opens sodium channels
• The depolarization displaces magnesium molecules that had been blocking NMDA
receptors
• Glutamate is then able to excite the NMDA receptorsopening a channel for calcium
ions to enter the neuron
• Entry of Calcium through MNDA channels activates the protein CaMKII,
o Sets a series of events in motion:
▪ Release of CREB goes to nucleus + regulates gene expression
▪ BDNF: enhance effects of CREB and CaMKIIcause action
potentials that start in axons to back propagate into the dendrite
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