13.4 Flashcards
What did Donald Hebb (1949) propose?
That when two neurons are repeatedly activated together, their synaptic connection will become stronger; these hebbian synapses could act together to store a memory trace
What is a hebbian synapses?
A synapses that is strengthened when it successfully drives the postsynaptic cell
What is tetanus?
A brief, high-frequency burst of electrical stimuli
What does tetanus do?
Causes presynaptic neurons to produce a high rate of action potentials; then the postsynaptic responds by producing larger EPSP; which then produces LTP
What is EPSP?
Excitatory postsynaptic potentials
What is LTP?
A stable and enduring increase in the effectiveness of synapses
Where does LTP occur at?
Pathways in the hippocampal formation- which consists of the hippocampus and the dentals gyrus
The most studied form of LTP uses the transmitter glutamate and depends on NDMA receptors along with AMPA receptors
During normal activity, what receptor does glutamate released at CA1 synapses activate?
AMPA receptors
NDMA receptors at rest
Has a magnesium ion (Mg+2) blocking their calcium (Ca2+) channels
When do NMDA receptors respond?
When larger quantities of glutamate are released
What happens when stronger stimulation of AMPA(which are responsible for LTP) receptors depolarizes the membrane?
It releases Mg2+ from the NMDA receptors; the NMDA then responds to the glutamate to allow Ca2+ to enter
When are NDMA fully active?
When “gated” by a combination of strong depolarization via AMPA and glutamate
What does the influx of Ca2+ activate?
Intracellular enzymes, which causes changes in the AMPA receptors
What are the changes in the AMPA receptors from the influx of Ca2+?
Existing receptors move to the active synapse
Increased conductance of ions
More receptors are produced
