I suspect the stimulation intensity of paired-pulse stimulation will affect whether it will be PPF or PPD, or the percentage of enhancement or depression. Please advise what the best the intensity of paired-pulse stimulation to correctly reflect the pre-synaptic release probability of given synapse.
A change in stimulation intensity will affect the number of stimulated axons and thus in principle not synaptic short-term plasticity. In theory, you may recruit a different type of axons with a different type of short term plasticity if you stimulate stronger. For example, medial and lateral perforate path synapses have very different STP. A very strong stimulus may activate the medial PP even when placing the stimulus electrode/pipette above or into the lateral PP. In such a scenario, stimulation strength would affect STP. Thus, you may want to avoid very strong stimulation. However, we tested the dependence of STP on stimulation intensity in the dentate gyrus and found little change when the stimulus elicited AMPA current amplitudes in a range of ca 50 pA up to a few hundreds pA. Hence, the effect of recruiting other pathways seemed not to be big in these experiments. On the other hand, the frequency and number of stimuli are very relevant for the amount and direction of STP.
Thank you very much Dr. Engelhardt! Sorry for the late of response, I lost track of my question.
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