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Different neural mechanisms underlie long-term potentiation at each of the three synapses in the trisynaptic pathway in the hippocampus. Long-term
potentiation (LTP) is present at synapses throughout the hippocampus but depends to differing degrees on activation of NMDA-type glutamate receptors.
A. Tetanic stimulation of the Schaffer collateral pathway (at arrow) induces LTP at the synapses between presynaptic terminals of CA3 pyramidal neurons
and their postsynaptic CA1 pyramidal neurons. The graph plots the size of the extracellular field EPSP (fEPSP) expressed as a percent of the initial
baseline fEPSP prior to induction of LTP. At these synapses LTP requires activation of the NMDA receptors in the CA1 neurons as it is completely blocked
when the tetanus
is delivered
inCortex,
the presence
of the NMDA
receptor
antagonist
(Reproduced,
with permission,
from
MorganFifth
andEditon
Teyler 2001.)
Source:
Prefrontal
Hippocampus,
and the
Biology
of ExplicitAPV.
Memory
Storage, Principles
of Neural
Science,
B. Tetanic stimulation
of the ER,
direct
pathwayJH,
from
entorhinal
cortex to CA1
neurons
generates
LTP
the fEPSP
that depends
partially
on activation
of the
Citation: Kandel
Schwartz
Jessell
TM, Siegelbaum
SA,
Hudspeth
AJ, Mack
S. of
Principles
of Neural
Science,
Fifth Editon;
2012 Available
2+ channels. It is therefore only partially blocked by APV. Addition of APV and
NMDA receptors and
partially
on
activation
of
L
type
voltage-gated
Ca
at: http://mhmedical.com/ Accessed: April 30, 2017
nitrendipine, Copyright
a dihydropyridine
that blocks LEducation.
- type channels,
is needed
© 2017 McGraw-Hill
All rights
reservedto fully inhibit LTP. (Reproduced, with permission, from Remondes and Schuman
2003.)