Abstract
The correspondence between pre- and postsynaptic fluctuations in generation of action potentials was studied using the inhibitory synapse on the crayfish stretch receptor neuron. The presynaptic discharges were imposed by an appropriately controlled stimulator modulated with triangular or sine waves at 1/60 to 10 cps by±1 to 10 ips and around an average rate of 5 to 10 ips. The rate of the regular postsynaptic discharge was set, in the absence of IPSPs, at 5 to 20 ips by the degree of constant stretch on the receptor organ. Cycle histograms were constructed, i.e. discharges were averaged across several cycles, presynaptically on the one hand and postsynaptically on the other. This exploration led to the recognition of some of the rules whereby the correspondence between spike trains is established across a synapse with IPSPs. The mapping or coding from the presynaptic to the postsynaptic cycle histogram was complex, and its main facets were: i) the possibility of the transfer of a broad spectrum of frequencies, at least from 1/60 to 10 cps; ii) a general tendency for faster presynaptic discharges to be associated with slower postsynaptic ones (i.e. a negative overall slope in the presynaptic rate-postsynaptic rate graph); iii) interspersed consistently located segments of appreciable size where inhibitory accelerations led to faster postsynaptic discharges (i.e. positively-sloped “paradoxical” segments); iv) a sensitivity to whether the presynaptic cell was accelerating or decelerating (hysteresis); and, finally, v) minimal consequences of changes around extremes where the receptor was either hardly affected or halted by very low or high rates, respectively (saturation). The type, magnitude and ubiquity of the deviations (iii, iv, v) from a simple and negatively-sloped linearity (suggested by ii) makes them integral and practically important facets of inhibitory transfer. The form of the correspondence depended on such issues as the overall pre- and postsynaptic rates (e.g. 5 versus 10 ips), the modulation frequency (e.g. 1/60 versus 2 cps) and depth (e.g.±1 versus 10 ips), etc. When restrictions were placed upon these variables, the correspondence adopted special forms whose particular descriptions (e.g. linear in- or out-of-phase, rectifier-like, etc.) were acceptable only if conditional to those restrictions. A rapid presynaptic irregularity which increased the varibility of individual cycles without altering the average cycle reduced, sometimes markedly, deviations from linearity. This demonstrates the applicability to the living synapse, represented here by a system whose input and output spike trains are assimilated to point processes, of a concept developed for system whose input or output are continuous: namely, that the addition at the input of a high frequency “dither” reduces the complexities of the element. This effect has interesting physiological possibilities and explains apparent discrepancies between earlier publications.
Similar content being viewed by others
References
Alexandrowicz, J.S.: Receptor elements in the thoracic muscles of Homarus vulgaris and Palimurus vulgaris. Quart. J. Microsc. Sci. 93, 315–346 (1952)
Brillinger, D.R.: The identification of point process systems. Ann. Probabil. 3, 909–924 (1975)
Brillinger, D.R., Bryant Jr., H.L., Segundo, J.P.: Identification of synaptic interactions. Biol. Cybernetics 22, 213–228 (1976)
Bryant, H.L., Ruiz Marcos, A., Segundo, J.P.: Correlations of neuronal spike discharges produced by monosynaptic connections and by common inputs. J. Neurophysiol. 36, 205–225 (1973)
Cox, D.R., Lewis, P.A.W.: The statistical analysis of series of events. London: Methuen, 1966
Eckert, R.O.: Reflex relationships of the abdominal stretch receptors of the crayfish. I. Feedback inhibition of the receptors. J. Cell Comp. Physiol. 57, 149–162 (1961a)
Eckert, R.O.: Reflex relationships of the abdominal stretch receptors of the crayfish. II. Stretch receptor involvement during the swimming reflex. J. Cell Comp. Physiol. 57, 163–174 (1961b)
Eyzaguirre, C., Kuffler, S.W.: Processes of excitation in the dendrites and in the soma of single isolated sensory nerve cells of the lobster and crayfish. J. Gen. Physiol. 39, 87–119 (1955)
Firth, D.T.: Interspike interval fluctuations in the crayfish stretch receptor. Biophys. J. 6, 201–215 (1966)
French, A.S., Holden, A.V., Stein, R.B.: The estimation of the frequency response function of a mechanoreceptor. Kybernetik 11, 15–23 (1972)
French, A.S., Wong, R.K.S.: The response of trochanteral hair plate sensilla in the cockroach to periodic and random displacements. Biol. Cybernetics 22, 33–38 (1976)
Gibbons, J.D.: Nonparametric statistical inference. New York: McGraw-Hill 1971
Grampp, W.: Firing with multiple-spike discharges in the slowly adapting stretch receptor neuron of the lobster. Acta physiol. scand. 66, 484–494 (1966)
Kuffler, S.W., Eyzaguirre, C.: Synaptic inhibition in an isolated nerve cell. J. Gen. Physiol. 39, 155–184 (1955)
Macadar, O., Wolfe, G.E., O'Leary, D.P., Segundo, J.P.: Response of the elasmobranch utricle to maintained spatial orientation, transitions and jitter. Exp. Brain Res. 22, 1–12 (1975)
Moore, G.P., Perkel, D.H., Segundo, J.P.: Stability patterns in interneuronal pacemaker regulations. Proc. San Diego Symp. Biomed. Engin., La Jolla (1963)
Njä, A., Walløe, L.: Reflex inhibition of the slowly adapting stretch receptors in the intact abdomen of the crayfish. Acta physiol. scand. 94, 177–183 (1975)
O'Leary, D.P., Wall III, C.: Dual input describing function analysis of spontaneously inactive first-order afferents innervating the isolated guitar-fish semicircular canal. In: Fifth annual meeting of the society of neuroscience, p. 222, New York 1975
Perkel, D.H., Schulman, J.H., Bullock, T.H., Moore, G.P., Segundo, J.P.: Pacemaker neurons: effects of regularly spaced synaptic input. Science 145, 61–63 (1964)
Schulman, J.: Signal Transfer Analysis of an Inhibitor-to-Pacemaker Synapse. Thesis, University of California, Los Angeles. (1969)
Segundo, J.P.: Communication and coding by nerve cells. In: The neurosciences: Second study program, pp. 569–586. Ed.: Schmitt, F.O. New York: Rockefeller University 1970
Simpson, R.J.: Use of high frequency signals in identification of certain non-linear systems. Int. J. Syst. Sci. 4, 121–127 (1973)
Stein, R.B.: The stochastic properties of spike trains recorded from nerve cells. In: Stochastic Point Processes: Statistical Analysis, Theory, and Applications, pp. 700–731. Ed. Lewis, P.A.W. New York: Wiley-Interscience 1972
Terzuolo, C.A., Bayly, E.J.: Data transmission between neurons. Kybernetik 5, 83–85 (1968)
Wilkins, L.A., Wolfe, G.E.: A new electrode design for en passant recording, stimulation and intracellular dye infusion. Comp. Biochem. Physiol. 48, 217–220 (1974)
Author information
Authors and Affiliations
Additional information
Supported by grants from the NIH and NSF (to J.P.S.), and by Fellowships from NIH (to G.E.W.) and from the Inter-Academy Exchange Program of the National Academy of Sciences (to B.F.T.)
Rights and permissions
About this article
Cite this article
Segundo, J.P., Tolkunov, B.F. & Wolfe, G.E. Relation between trains of action potentials across an inhibitory synapse. Influence of presynaptic irregularity. Biol. Cybernetics 24, 169–179 (1976). https://doi.org/10.1007/BF00364120
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00364120