In article <4a6dlv$5bq at nntp.Stanford.EDU> Dan Roseman,
roseman at leland.stanford.edu writes:
>Here's a hypothetical question: could there be a possible mechanism
>whereby presynaptic inhibition of synaptic afferents to CA1 pyramidal
>cells could enhance the induction of long-term potentiation?
Reduction of GABA-mediated inhibition in CA1 facilitates LTP induction,
and there appears to be an endogenous presynaptic mechanism for this.
GABAergic terminals have GABA-B receptors, which reduce GABA output when
activated. One LTP-induction protocol involves "priming" these GABA-B
receptors with a single stimulus to the Schaffer pathway, which causes
both the release of GABA and glutamate. The GABA activates presynaptic
GABA-B receptors on inhibitory terminals, and reduces subsequent
inhibition for several hundred milliseconds. A second burst of stimuli
during this period is more likely to induce LTP.