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Biomedical subjects

D S Faber

Publications and source records attributed to D S Faber.

At least 91 records · Page 5Linked to original sources
PubMed1981

Mauthner axon diameter and impulse conduction velocity decrease with growth of goldfish.

Conduction velocities of antidromically evoked impulses along the goldfish Mauthner axon were found to be inversely correlated with body length. To test the hypothesis that such a relation is accompanied by a reduction in axonal diameter with increasing fish size, Mauthner axon diameters were measured. A parabolic relationship with respect to body length was obtained, axonal diameter being maximal in 9.5 cm fish. To our knowledge, this is the first report of a decrease in conduction velocity and axonal size during growth of an organism were functioning of the cell is maintained.

Aging↗
PubMed1981

Axotomy-induced changes in cell structure and membrane excitability are sustained in a vertebrate central neuron.

The retrograde reactions of the goldfish Mauthner neuron to axotomy 8-10 mm caudal to its soma are detectable within a few weeks and persist for more than 200 days. Morphological changes include chromatolysis, reflecting a redistribution of cytoplasmic ribosomes, and infolding of the nuclear membrane. At the time, the normally inexcitable soma-dendritic membrane becomes capable of impulse initiation; this induced excitability also persists for at least 200 days.

Action Potentials↗
PubMed1981

Fluctuating responses at a central synapse: n of binomial fit predicts number of stained presynaptic boutons.

Binomial predictions provided a better description than the Poisson law of fluctuating unitary inhibitory postsynaptic potentials evoked in the goldfish Mauthner cell by impulses in presynaptic interneurons. The number of terminal boutons established on this target cell by each horseradish peroxidase-filled interneuron corresponded to the value of the binomial parameter n.

Animals↗
PubMed1981

Myelinated central vertebrate axon lacks voltage-sensitive potassium conductance.

Intracellular recordings were obtained from the goldfish Mauthner cell soma and axon before and after intracellular iontophoresis of drugs that block voltage-sensitive potassium conductance. Analysis of the action potentials generated by the axon hillock-initial segment and by the axon suggest that axonal impulses lack this potassium conductance. Thus, impulse repolarization in the Mauthner axon, and perhaps in other vertebrate central axons, may not involve an active potassium current.

4-Aminopyridine↗
PubMed1980

Single-shot channel activation accounts for duration of inhibitory postsynaptic potentials in a central neuron.

In the goldfish Mauthner cell, inhibitory postsynaptic currents evoked by intracellular stimulation of presynaptic neurons decay exponentially, with a mean time constant of 6.65 milliseconds. Analysis of membrane conductance fluctuations induced by iontophoresis of glycine and gamma-aminobutyric acid indicates a mean inhibitory channel lifetime of 7.15 milliseconds. The results thus suggest that the relaxation kinetics of activated inhibitory channels are rate-limiting during decay of the inhibitory postsynaptic current.

Animals↗
PubMed1978

Structural correlates of recurrent collateral interneurons producing both electrical and chemical inhibitions of the Mauthner cell.

Intracellular injections of horseradish peroxidase provided a basis for morphological identification of inhibitory interneurons belonging to the recurrent collateral network of the Mauthner cell. Their axons dilate to form unusually large bulbs surrounding the axon cap. The morphological appearance of these bulbs as well as intracellular recordings at their level indicate that they behave as nodes and serve as a final source of current for electrical inhibition of the Mauthner cell. The axon of each interneuron gives rise to two different groups of fibres which are respectively fitted for the mediation of electrical and chemical inhibitions of their target cell.

Animals↗
PubMed1976

Vertebrate central nervous system: same neurons mediate both electrical and chemical inhibitions.

Identified goldfish medullary interneurons previously shown to inhibit the Mauthner cell electrically also produce a classical postsynaptic inhibition of that cell. Failure of active spike propagation in the processes of these interneurons underlies generation of the electrical component, and the resultant electrotonic terminal depolarization is sufficient to evoke inhibitory transmitter release.

Action Potentials↗