Adaptive rundown of excitatory post‐synaptic potentials at synapses between hair cells and eight nerve fibres in the goldfish.

1. The excitatory post‐synaptic potentials (e.p.s.p.s.) evoked by sound stimuli were recorded intracellularly from large afferent eight nerve fibres in the sacculus of the goldfish (S1 fibres). The fish were anaesthetized with MS‐222 and spike potentials were suppressed with locally applied tetrodotoxin. 2. The e.p.s.p.s. successively evoked in response to each wound wave showed a marked rundown in size, while no reduction was observed in the microphonic potentials. The amplitude of successive e.p.s.p.s was reduced keeping approximately a fixed ratio to the preceding ones, suggesting that the rundown is attributable to a depletion of transmitter quanta from the release sites. 3. The rate of rundown of successive e.p.s.p.s, however, remained almost unchanged when the intensity of the stimulus sound was changed. It was also observed that, even after the e.p.s.p.s had been completely adapted to a continuous sound, a vigorous discharge of new e.p.s.p.s was observed when the intensity of the sound was increased. 4. These findings seem to indicate that it is the size of the readily available store and not the release fraction that is changed by a change in the sound intensity. 5. The saccular macula was superfused with solutions different in Ca and Mg ion concentrations. High Ca ion concentration brought about an increase in the size of the readily available store as well as the release fraction. 6. Mechanisms underlying these observations were discussed in terms of the quantal release mechanism as well as the morphology of the release sites.

[1]  M. Bennett,et al.  The effect of calcium ions on the binomial statistic parameters that control acetylcholine release at preganglionic nerve terminals. , 1976, The Journal of physiology.

[2]  T. Furukawa,et al.  Quantal analysis of the size of excitatory post‐synaptic potentials at synapses between hair cells and afferent nerve fibres in goldfish. , 1978, The Journal of physiology.

[3]  J. Simpson THE RELEASE OF NEURAL TRANSMITTER SUBSTANCES , 1969 .

[4]  K Kusano,et al.  Depression and recovery of transmission at the squid giant synapse. , 1975, The Journal of physiology.

[5]  A. R. Martin,et al.  A further study of the statistical composition of the end‐plate potential , 1955, The Journal of physiology.

[6]  B. Katz,et al.  Further study of the role of calcium in synaptic transmission , 1970, The Journal of physiology.

[7]  T. Furukawa,et al.  Neurophysiological studies on hearing in goldfish. , 1967, Journal of neurophysiology.

[8]  T. Furukawa,et al.  An input-output relation at the synapse between hair cells and eighth nerve fibers in goldfish. , 1971, The Japanese journal of physiology.

[9]  A TAKEUCHI,et al.  The long-lasting depression in neuromuscular transmission of frog. , 1958, The Japanese journal of physiology.

[10]  J. Hubbard Repetitive stimulation at the mammalian neuromuscular junction, and the mobilization of transmitter , 1963, The Journal of physiology.

[11]  T. Furukawa,et al.  Synaptic delay and time course of postsynaptic potentials at the junction between hair cells and eighth nerve fibers in the goldfish. , 1972, The Japanese journal of physiology.

[12]  F. Dodge,et al.  Co‐operative action of calcium ions in transmitter release at the neuromuscular junction , 1967, The Journal of physiology.

[13]  A. A. Auerbach,et al.  A Rectifying Electrotonic Synapse in the Central Nervous System of a Vertebrate , 1969, The Journal of general physiology.

[14]  J. Goldberg,et al.  Physiology of peripheral neurons innervating semicircular canals of the squirrel monkey. I. Resting discharge and response to constant angular accelerations. , 1971, Journal of neurophysiology.

[15]  T. Furukawa,et al.  An analysis of microphonic potentials of the sacculus of goldfish. , 1972, The Japanese journal of physiology.

[16]  M. Bennett,et al.  The effect of calcium ions on the binomial statistic parameters which control acetylcholine release at synapses in striated muscle. , 1975, The Journal of physiology.

[17]  A. R. Martin,et al.  Estimates of probability of transmitter release at the mammalian neuromuscular junction , 1970, The Journal of physiology.

[18]  NEUROPHYSIOLOGICAL STUDIES , 1971 .

[19]  J. Eccles,et al.  Synaptic action during and after repetitive stimulation , 1960, The Journal of physiology.

[20]  R E Thies,et al.  NEUROMUSCULAR DEPRESSION AND THE APPARENT DEPLETION OF TRANSMITTER IN MAMMALIAN MUSCLE. , 1965, Journal of neurophysiology.

[21]  K. Ikeda,et al.  Effects of Na + , K + , and ouabain on microphonic potentials of the goldfish inner ear. , 1971, The Japanese journal of physiology.

[22]  M. Bennett,et al.  An electrophysiological analysis of the storage of acetylcholine in preganglionic nerve terminals , 1972, The Journal of physiology.

[23]  T. Furukawa Synaptic interaction at the mauthner cell of goldfish. , 1966, Progress in brain research.

[24]  A. W. Liley,et al.  An electrical investigation of effects of repetitive stimulation on mammalian neuromuscular junction. , 1953, Journal of neurophysiology.

[25]  I. Russell,et al.  Inhibition by efferent nerve fibres: action on hair cells and afferent synaptic transmission in the lateral line canal organ of the burbot Lota lota. , 1976, The Journal of physiology.

[26]  K. Hama,et al.  Fine structure of the afferent synapse of the hair cells in the saccular macula of the goldfish, with special reference to the anastomosing tubules , 1977, Journal of Neurocytology.

[27]  W. Betz,et al.  Depression of transmitter release at the neuromuscular junction of the frog , 1970, The Journal of physiology.

[28]  T. Reese,et al.  EVIDENCE FOR RECYCLING OF SYNAPTIC VESICLE MEMBRANE DURING TRANSMITTER RELEASE AT THE FROG NEUROMUSCULAR JUNCTION , 1973, The Journal of cell biology.

[29]  A. Wernig The effects of calcium and magnesium on statistical release parameters at the crayfish neuromuscular junction , 1972, The Journal of physiology.

[30]  D. Elmqvist,et al.  A quantitative study of end‐plate potentials in isolated human muscle. , 1965, The Journal of physiology.

[31]  C. Platt Hair cell distribution and orientation in goldfish otolith organs , 1977, The Journal of comparative neurology.

[32]  S. W. Kuffler,et al.  NATURE OF THE "ENDPLATE POTENTIAL" IN CURARIZED MUSCLE , 1941 .

[33]  R. Perkins,et al.  A study of cochlear innervation patterns in cats and rats with the Golgi method and Nomarski optics , 1975, The Journal of comparative neurology.

[34]  J. Hubbard Microphysiology of vertebrate neuromuscular transmission. , 1973, Physiological reviews.

[35]  S. Zottoli,et al.  Correlation of the startle reflex and Mauthner cell auditory responses in unrestrained goldfish. , 1977, The Journal of experimental biology.

[36]  A. Wernig Estimates of statistical release parameters from crayfish and frog neuromuscular junctions. , 1975, The Journal of physiology.

[37]  M. Bennett,et al.  An electrophysiological analysis of the synthesis of acetylcholine in preganglionic nerve terminals , 1972, The Journal of physiology.

[38]  M. D. Miyamoto Binomial analysis of quantal transmitter release at glycerol treated frog neuromuscular junctions. , 1975, The Journal of physiology.

[39]  J. Diamond,et al.  Startle-response in Teleost Fish: an Elementary Circuit for Neural Discrimination , 1968, Nature.

[40]  H. Spoendlin Innervation densities of the cochlea. , 1972, Acta oto-laryngologica.

[41]  Y. Nakajima,et al.  Morphology of afferent and efferent synapses in hearing organ of goldfish , 1974 .

[42]  D. W. Esplin,et al.  Rates of transmitter turnover in the cat superior cervical ganglion estimated by electrophysiological techniques. , 1971, Journal of neurophysiology.