https://science.sciencemag.org/content/sci/150/3699/971.full.pdf

Pain mechanisms: a new theory.

Impulses and Physiological States in Theoretical Models of Nerve Membrane

Pain mechanisms: A new theory

Identification of a novel force-generating protein, kinesin, involved in microtubule-based motility

https://www.cell.com/cell/pdf/S0092-8674(03)00111-9.pdf

The Molecular Motor Toolbox for Intracellular Transport

THE METHOD of tissue culture offers a unique opportunity for investigating electrophysiological properties of single cells by means of microelectrodes under direct visual control. Crain (13) has published microelectrode record? ings of the action potentials from spinal ganglion cells of chicken embryos. Hild et al. (26) have reported electrophysiological findings on glial elements from the mammalian brain maintained in vitro. Recently, Cunning.ham and Rylander (14) investigated electric properties of brain tissue from chicken embryos (10 days incubation) which was kept in vitro for up to 120 hours; these investigators were, however, interested more in the behavior of the tissue as a whole and did not investigate at the cellular level. It seemed of great interest to extend our earlier observations since it is possible at present to maintain neurons in vitro in good condition for extended periods of time. In many instances protoplasmic processes of living neurons can easily be observed under a phase-contrast microscope. It is generally easy to distinguish dendrites from axons in such preparations. It is possible, therefore, to investigate the electrophysiological properties of various parts of a nerve cell under direct visual control. Obviously, the present method differs greatly from that in previous studies in which properties of the neuron soma and dendrites were inferred from the electric responses recorded from the gray matter with macroelectrodes or from the data of single cell recordings without any knowledge as to the position of the microelectrode relative to the cells under study. The first half of the present paper deals with the results of our observations on the neuron soma and the dendrite by this method. In the second half, we are concerned with a comparison of electrophysiological properties of neurons with those of neuroglial cells and of macrophages.

Morphological and physiological properties of neurons and glial cells in tissue culture.

T HAS BEEN SHOWN that the myelin sheath and the surface membrane at the node of Ranvier of the myelinated nerve fiber behave, to a weak penetrating current, like a condenser with an ohmic resistance connected in parallel (1–5). The absolute values of these capacities and resistances have been estimated already with some accuracy. In order to analyze the process of action potential production at the nodal membrane, it is desirable to obtain more accurate measurements on the physical constants of the membranes at rest. In the present investigation, the physical constants of the myelin sheath were measured by recording the current that passes through this membrane when two nerve impulses, each coming from an end of a single fiber preparation, collide at the internode under investigation. This collision of impulses (6) makes the spatial distribution of the potential inside the myelin sheath uniform and consequently increases the accuracy of the measurement. Measurements of the capacity and the resistance of the resting nodal membrane were made, using the collision technique, on a node treated with a sodium-free Ringer or with a diluted cocaine-Ringer solution. The effects of several chemicals and of temperature changes upon the physical properties of the nerve membrane were investigated by the same technique.

New measurements of the capacity and the resistance of the myelin sheath and the nodal membrane of the isolated frog nerve fiber.

conclusions. With this technique it is easy to record sensory discharges in single nerve fibres which develop overwhelmingly large action potentials or in fibres with especially low threshold for sensory stimuli. It is, however, extremely difficult to explore the behaviour of nerve endings which on stimulation give rise to a limited number of small action potentials, because the discharges in these fibres may be completely masked by those in other predominant fibres. This and other defects of the technique can undoubtedly be circumvented by using a single isolated fibre of the desired size for the experiments. Since 1942 one of. us (LT.), in collaboration with several co-workers who changed from time to time, has devoted much effort to exploring the physiological properties of various sensory nerve endings with the single fibre technique. By means of the experimental set-up we are using now, it is possible to observe afferent impulses in a single nerve fibre, either myelinated

https://physoc.onlinelibrary.wiley.com/doi/pdf/10.1113/jphysiol.1952.sp004736

Action currents in single afferent nerve fibres elicited by stimulation of the skin of the toad and the cat.

EVER SINCE the time of Helmholtz, most physiologists have believed that different parts of the cochlea respond differently to various sound stimuli. Almost all the experimental evidence in support of this belief has been of rather indirect nature, however, and consequently there have been some differences of opinion among physiologists as to just how the behavior of the apical turn of the cochlea differs from that of the basal turn (see 8, 9). The differences might be resolved if we had a technique by which the responses of a part interferin of the g with cochlea could the responses be of recorded, modified or eliminated without the remaining parts of the cochlea. The method of destroying the apical part of the cochlea has frequently been used by previous investigators, but it has several obvious disadvantages. For example, destruction of the apex may change the acoustic properties of the whole cochlea, the method cannot be applied to the other parts of the cochlea, and destruction of the apex may change the excitability of th .e sensory cells in the remaining parts of the cochlea. In the present investigation we undertook to develop micro-techniques by which the condition of a part of the cochlea could be modified in a reversible manner. We have succeeded in recording electrical responses generated in any one of the turns of the cochlea without any significant contamination by the responses from other turns. Administration of an isotonic potassium chloride solution and application of direct current were chosen to modify locally the condition of the cochlea, because these agents are known to change reversibly both resting and action potentials in many other excitable tissues. Actually these agents were found to be very convenient for changing or totally suppressing these electrical signs of cochlear activity in a restricted region where the agents were applied. The results show very clearly that the basal turn of the cochlea generates cochlear microphonics in response to both highand low-frequency sound stimuli, whereas in the apical part high-frequency sound stimuli, applied through the external auditory meatus, do not give any response. Furthermore, the cochlear microphonics recorded from the round window of the guinea pig are the response of the basal turn and give practically no information about the activity of the more distant parts of the cochlea.

Ichiji Tasaki

Papers

Morphological and physiological properties of neurons and glial cells in tissue culture.

New measurements of the capacity and the resistance of the myelin sheath and the nodal membrane of the isolated frog nerve fiber.

Action currents in single afferent nerve fibres elicited by stimulation of the skin of the toad and the cat.

MODIFICATION OF COCHLEAR MICROPHONICS AND ACTION POTENTIALS BY KCl SOLUTION AND BY DIRECT CURRENTS

Effect of Monovalent-Divalent Cation Exchange on the Swelling of Polyacrylate Hydrogels in Physiological Salt Solutions