scholarly journals Resting and action potentials in single nerve fibres

1945 ◽  
Vol 104 (2) ◽  
pp. 176-195 ◽  
Author(s):  
A. L. Hodgkin ◽  
A. F. Huxley
Keyword(s):  
Action Potentials ◽  
Nerve Fibres ◽  
Single Nerve

Unit Activity in the Abdominal Nerve Cord of a Dragonfly NYMPH

1962 ◽  
Vol 39 (1) ◽  
pp. 31-44
Author(s):  
ANN FIELDEN ◽  
G. M. HUGHES
Keyword(s):  
Action Potentials ◽  
The Body ◽  
Peripheral Stimulus ◽  
Inhibitory Effects ◽  
Nerve Fibres ◽  
Dragonfly Nymph ◽  
Peripheral Area ◽  
Segmental Ganglion ◽  
Peripheral Areas ◽  
Stimulation Of

1. Electrical activity of single units has been studied in small bundles of nerve fibres split off from the connectives between abdominal ganglia of the dragonfly nymph. Many units showed a resting discharge but activity of other units was only found when the insect was stimulated mechanically. 2. In some fibres the resting discharge was unaffected by mechanical stimulation and such spontaneous activity showed different patterns. These units were identified as interneurones and a prominent feature of their discharge was an irregular firing over long periods and the formation of characteristic intermittent bursts. 3. Responses to tactile or proprioceptive stimulation were investigated in primary sensory fibres and interneurones. The latter showed excitatory and inhibitory effects which were often related to the site of the peripheral stimulus. 4. Primary sensory fibres generally gave action potentials of smaller amplitude and were excited by stimulation of more localized areas. Many fibres traverse at least one connective after they enter a segmental ganglion and most ascend or descend ipsilaterally, but some crossing-over of sensory fibres occurs in the ganglia. 5. Interneurones were classified according to the nature of the peripheral areas from which they received their input. Ipsilateral, contralateral, and bilateral fibres have all been found but so far there is no evidence for any asymmetric fibres. Fibres responding to stimulation of a single segment or of many segments were found. Some of the latter extended over the whole length of the body and it is clear that spikes may be initiated in many of the ganglia through which an interneurone passes. 6. It is evident from this work that a given peripheral area is represented centrally by many interneurones and a great deal of convergence from different areas may occur on individual interneurones.

scholarly journals XIV.—On the Relation of Nerves to Odontoblasts, and on the Growth of Dentine

1892 ◽  
Vol 36 (2) ◽  
pp. 321-333 ◽  
Author(s):  
W. G. Aitchison Robertson
Keyword(s):  
Nervous System ◽  
Nerve Trunk ◽  
The Body ◽  
Osmic Acid ◽  
Nerve Fibres ◽  
Incisor Tooth ◽  
Highly Sensitive ◽  
Single Nerve ◽  
Lateral Branches ◽  
External Stimuli

Clinical and pathological observation both show that the dentine of the tooth is very closely connected with the nervous system, and is in consequence highly sensitive. Upon what structures does the sensibility of the dentine depend? In what manner is the dentine connected with the nerves of the pulp so as to become so sensitive to external stimuli?Perhaps there is no other structure in the body which is so largely supplied with nerves as the pulp of the tooth; even in the smallest fragment we find many nerve fibres. If we take the pulp from the incisor tooth of an ox and examine it after having allowed it to lie in a solution of osmic acid for a few minutes, we can see clearly through the darkened semi-transparent tissue a large blackened nerve trunk passing up the centre of the pulp, giving off on its way innumerable lateral branches, and dividing in a brush-like manner near the upper part of the pulp. All the fine branches are directed towards the periphery of the pulp. In longitudinal sections of the pulp we can see the same in greater detail; many large bundles of medullated and non-medullated nerve fibres running longitudinally near the centre and giving off lateral branches, which are found in great numbers near the periphery and divide into single nerve fibres just under the odontoblastic layer, being specially numerous at the apex of the pulp.

scholarly journals Initial boundary value problems for coupled nerve fibres

1985 ◽  
Vol 28 (2) ◽  
pp. 249-269
Author(s):  
P. Grindrod
Keyword(s):  
General Model ◽  
Action Potentials ◽  
Geometric Approach ◽  
Initial Boundary ◽  
Initial Boundary Value Problems ◽  
Electrical Behaviour ◽  
Nerve Fibres ◽  
Membrane Action ◽  
Image Position ◽  
Initial Boundary Value

In this paper we analyse the electrical behaviour within systems of long and short coupled nerve axons by using a geometric approach to obtain a priori bounds on solutions. In [4[ we developed a general model for a bundle of n-uniform unmylinated nerve fibres. If FitzHugh-Nagumo dynamics, [3[ are used to describe the ionic membrane currents, then the model takes the formHere W=(w1,…wn)T denotes the membrane action potentials for each fibre in the bundle and Z=(Z1,…Zn)T represents the recovery variables for each fibre, which control the return to the resting equilibrium after any transmission of signals.

An intracellular study of chemosensory fibers and endings

1980 ◽  
Vol 44 (6) ◽  
pp. 1077-1088 ◽  
Author(s):  
Y. Hayashida ◽  
H. Koyano ◽  
C. Eyzaguirre
Keyword(s):  
Carotid Body ◽  
Action Potentials ◽  
Physiological Saline ◽  
Mean Amplitude ◽  
Nerve Fibers ◽  
Chemical Stimulation ◽  
Nerve Terminals ◽  
Generator Potential ◽  
Single Nerve ◽  
Frequency Changes

1. The carotid body and its nerve, removed from anesthetized cats, were placed in physiological saline flowing under paraffin oil. The nerve, lifted into the oil, was used for either electrical stimulation or recording of the total afferent discharge. Intracellular recordings were obtained from individual nerve fibers and endings within the carotid body. The recording sites were identified by injecting Procion yellow through the intracellular electrodes; the tissues were then prepared for histology and observed with episcopic fluorescence or Nomarski optics. 2. Intracellularly recorded chemosensory fibers conducted at 1.1-30 m/s and usually displayed action potentials of regular amplitude. At times, however, some spikes become partially blocked while others maintained their original amplitude. "Natural" (hypoxia) or chemical (ACh or NaCN) stimulation induced different patterns of frequency changes of the large and small action potentials. This indicated nerve fiber branching at some distance from the recording site. 3. Intra- and extracellularly recorded spikes were blocked in 0 [Na+]0 by tetrodotoxin (TTX) or procaine. 4. During chemical stimulation, a slowly occurring depolarization (receptor or generator potential) was recorded intracellularly from the afferent fibers. It developed concomitantly with the increase in discharge. 5. Impalement of single nerve terminals (histologically identified) showed numerous "spontaneous" depolarizing potentials (SDPs) that had a mean amplitude of 5.6 mV, a mean duration of 46.1 ms, and nearly random distribution. They increased in frequency and summated during chemical stimulation. SDPs originated from either the site of recording or from neighboring areas. When the SDPs attained a certain amplitude, they seemed to give rise to action potentials. Also, relatively well developed or partially blocked spikes (apparently originating elsewhere) were recorded from single nerve terminals. 6. The receptor (generator) potential of chemosensory receptors appears to be an integrated response formed by multiple activity originating in different nerve endings.

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