{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,25]],"date-time":"2026-09-25T23:59:30Z","timestamp":1790380770389,"version":"4.1.0"},"reference-count":0,"publisher":"American Physiological Society","issue":"4","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Journal of Neurophysiology"],"published-print":{"date-parts":[[1993,4,1]]},"abstract":"<jats:p> 1. The heartbeat central pattern-generating network of the medicinal leech contains elemental neural oscillators, comprising reciprocally inhibitory pairs of segmental heart interneurons, that use graded as well as spike-mediated synaptic transmission. We are in the process of developing a general computer model of this pattern generator. Our modeling goal is to explore the interaction of membrane currents and synaptic transmission that promote oscillation in heart interneurons. As a first step toward this goal, we have developed a computer model of graded synaptic transmission between reciprocally inhibitory heart interneurons. Previously gathered voltage-clamp data of presynaptic Ca2+ currents and simultaneous postsynaptic currents and potentials (5 mM external [Ca2+]) were used as the bases of the model. 2. We assumed that presynaptic Ca2+ current was composed of distinct fast (ICaF) and slow (Icas) components because there are two distinct time courses of inactivation for this current. We fitted standard Hodgkin-Huxley equations (Eq. 1 and 2, APPENDIX) to these components using first-order activation and inactivation kinetics. 3. Graded synaptic transfer in the model is based on calculation of a dimensionless variable [P]. A portion of both IcaF and ICaS determined by a factor A contributes to [P], and a removal factor B decreases [P] (Eq. 4, APPENDIX). [P] can be roughly equated to the [Ca2+] in an unspecified volume that is effective in causing transmitter release. Transmitter release, and thus postsynaptic conductance, is related to [P]3 (Eq. 3, APPENDIX). 4. We adapted our model to voltage-clamp data gathered at physiological external [Ca2+] (2.0 mM) and tested it for shorter presynaptic voltage steps. Presynaptic Ca2+ currents and synaptic transfer were well simulated under all conditions. 5. The graded synaptic transfer model could be used in a network simulation to reproduce the oscillatory activity of a reciprocally inhibitory pair of heart interneurons. Because synaptic transmission in the model is an explicit function of presynaptic Ca2+ current, the model should prove useful to explore the interaction between membrane currents and synaptic transmission that promote and modulate oscillation in reciprocally inhibitory heart interneurons. <\/jats:p>","DOI":"10.1152\/jn.1993.69.4.1225","type":"journal-article","created":{"date-parts":[[2017,12,25]],"date-time":"2017-12-25T03:02:01Z","timestamp":1514170921000},"page":"1225-1235","source":"Crossref","is-referenced-by-count":25,"title":["A model of graded synaptic transmission for use in dynamic network simulations"],"prefix":"10.1152","volume":"69","author":[{"given":"E.","family":"De Schutter","sequence":"first","affiliation":[{"name":"Department of Biology, Emory University, Atlanta, Georgia 30322."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"J. D.","family":"Angstadt","sequence":"additional","affiliation":[{"name":"Department of Biology, Emory University, Atlanta, Georgia 30322."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"R. L.","family":"Calabrese","sequence":"additional","affiliation":[{"name":"Department of Biology, Emory University, Atlanta, Georgia 30322."}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"24","container-title":["Journal of Neurophysiology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.physiology.org\/doi\/pdf\/10.1152\/jn.1993.69.4.1225","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2019,9,9]],"date-time":"2019-09-09T05:21:33Z","timestamp":1568006493000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.physiology.org\/doi\/10.1152\/jn.1993.69.4.1225"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1993,4,1]]},"references-count":0,"journal-issue":{"issue":"4","published-print":{"date-parts":[[1993,4,1]]}},"alternative-id":["10.1152\/jn.1993.69.4.1225"],"URL":"https:\/\/doi.org\/10.1152\/jn.1993.69.4.1225","relation":{},"ISSN":["0022-3077","1522-1598"],"issn-type":[{"value":"0022-3077","type":"print"},{"value":"1522-1598","type":"electronic"}],"subject":[],"published":{"date-parts":[[1993,4,1]]}}}