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LTP in hippocampus

Matt Jones jonesmat at ohsu.edu
Wed Nov 1 18:33:51 EST 1995

In article <KEVIN.95Nov1110807 at gaba> Kevin Hellman, kevin at gaba writes:
>physiologist, I am skeptical about the role ltp in the hippocampus.
>The paradigms used require an unusual amount of stimulation.  LTP

Some LTP-inducing protocols are pretty reasonable. There's one called
"primed-burst" where a single stimulus is followed 150-200 ms later by a
short train of stimuli. The idea is that the first stimulus causes both
glutamate (monosynaptic pathway) and GABA (polysynaptic pathway) release.
GABA then acts at presynaptic GABA-B autoreceptors on the inhibitory
terminals to suppress subsequent GABA release. This effect is maximal at
about 150-200 ms, so when the short train of stimuli comes along, there's
very little inhibition, and a bigger and longer glutamatergic
depolarization results. Interestingly, 150-200 ms corresponds to about
5-7 Hz, which is roughly the frequency of the hippocampal theta rhythm. 

For more on this method, see Diamond et al. J. Neurosci. 8:4079-4088, and
Davies et al. Nature 349:609-611.

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