Local synaptic interactions in the rat striatum in vitro: a quantitative analysis based on unit discharges.
The functioning of local circuits in the striatum maintained in vitro was studied using a new quantitative means to analyze single-unit responses. Measurements of the threshold for monosynaptically activated neurons to each of the stimuli in a paired-pulse protocol were made at various interstimulus intervals. The difference in thresholds between the first (conditioning) and second (test) stimuli was found to be independent of absolute threshold intensity, but to vary linearly with the interstimulus interval. From this information threshold difference versus interstimulus interval curves were constructed and shown to be constant from neuron to neuron under a given experimental condition, but to change in different ionic and drug environments. Such curves demonstrated: a change from paired-pulse facilitation in a [Ca2+] of 1.5 mM to paired-pulse inhibition in a [Ca2+] of 3.5 mM; a lack of effect of reserpine treatment on paired-pulse responses; and an enhancement of paired-pulse facilitation with physostigmine. The agreement of these results with the findings provided by other types of analysis validates the approach outlined here which offers a number of advantages for studying intrinsic striatal synapses.
D000109:Acetylcholine / Q000502:physiology*; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002118:Calcium / Q000502:physiology; D003342:Corpus Striatum / Q000502:physiology*; D004298:Dopamine / Q000378:metabolism / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D010830:Physostigmine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011930:Reaction Time; D012110:Reserpine / Q000494:pharmacology; D013569:Synapses / Q000502:physiology*
D012110:Reserpine; D010830:Physostigmine; D000109:Acetylcholine; D002118:Calcium; D004298:Dopamine