PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 173122

[Modelling of biological encoding mechanisms as a system with distributed parameters].

J Kugler·B Michaelis
View original source ↗Export metadata ↓

Abstract

The encoder region in receptors and neurons is represented by the inhomogeneous origin of the axon. The axon diameter and the excitability are in fact space-dependent. For the analysis the soma is described by a system with concentrated parameters followed by an inhomogeneous axon. The membrane properties are approximated by the slightly modified Hodgkin-Huxley equations. The assumption that the space-dependence of the excitability originates in variations of the conductance value for sodium ions accounts for a number of experimental results. The influence of other membrane parameters upon the mechanism of impulse generation and transmission has also been analysed.

Explore related subjects

AxonsCell MembraneCyberneticsMembrane PotentialsModels, BiologicalSynaptic TransmissionTransducersEnglish AbstractJournal Article

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

J Kugler, B Michaelis. 1975. [Modelling of biological encoding mechanisms as a system with distributed parameters].. https://pubmed.ncbi.nlm.nih.gov/173122/

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2007

Na(v)1.7 sodium channel expression in human lingual nerve neuromas.

OBJECTIVE: Peripheral branches of the trigeminal nerve are often damaged during the removal of lower third molar teeth, and a small proportion of patients who sustain an injury develop persistent chronic pain. The cause of the pain is not clear and there are no satisfactory methods of treatment. The aim of the present study was to examine the expression of the sodium channel subtype Na(v)1.7 in damaged human lingual nerves, and to identify any association between Na(v)1.7 expression and reported symptoms of dysaesthesia. METHODS: Eleven neuromas-in-continuity (NICs) and 11 nerve-end neuromas (NENs) were studied, and were all obtained at the time of surgical repair of the damaged lingual nerve. Specimens were categorised as being obtained from patients with symptoms or without symptoms, according to the degree of pain, tingling or discomfort that had been experienced. The tissue was prepared and processed for indirect immunofluorescence, and image analysis was used to quantify the percentage area of PGP 9.5-labelled tissue that also contained Na(v)1.7. RESULTS: The results demonstrated that sodium channel Na(v)1.7 was expressed in human lingual nerve neuromas. There was no direct relationship between the level of expression of Na(v)1.7 and the patients' symptoms of dysaesthesia. However, in NICs there was found to be an inverse correlation between Na(v)1.7 and macrophage expression, and in symptomatic NICs a direct correlation was found between Na(v)1.7 expression and axonal apposition. CONCLUSIONS: These data suggest that Na(v)1.7 expression alone does not play a primary role in initiating the painful symptoms of dysaesthesia. The development of neuropathic pain may involve complex interactions including changes in ultrastructure and ion channel density.

Axons↗
PubMed2007

Uremic neuropathy: clinical features and new pathophysiological insights.

Neuropathy is a common complication of end-stage kidney disease (ESKD), typically presenting as a distal symmetrical process with greater lower-limb than upper-limb involvement. The condition is of insidious onset, progressing over months. and has been estimated to be present in 60%-100% of patients on dialysis. Neuropathy generally only develops at glomerular filtration rates of less than 12 ml/min. The most frequent clinical features reflect large-fiber involvement, with paresthesias, reduction in deep tendon reflexes, impaired vibration sense, muscle wasting, and weakness. Nerve conduction studies demonstrate findings consistent with a generalized neuropathy of the axonal type. Patients may also develop autonomic features, with postural hypotension, impaired sweating, diarrhea, constipation, or impotence. The development of uremic neuropathy has been related previously to the retention of neurotoxic molecules in the middle molecular range, although this hypothesis lacked formal proof. Studies utilizing novel axonal excitability techniques have recently shed further light on the pathophysiology of this condition. Nerves of uremic patients have been shown to exist in a chronically depolarized state prior to dialysis, with subsequent improvement and normalization of resting membrane potential after dialysis. The degree of depolarization correlates with serum K(+), suggesting that chronic hyperkalemic depolarization plays an important role in the development of nerve dysfunction in ESKD. These recent findings suggest that maintenance of serum K(+) within normal limits between periods of dialysis, rather than simple avoidance of hyperkalemia, is likely to reduce the incidence and severity of uremic neuropathy.

Axons↗
PubMed2007

Neural engineering to produce in vitro nerve constructs and neurointerface.

OBJECTIVE: Recently, our laboratory recapitulated a natural form of axon growth that occurs between late embryogenesis and early adulthood. In this article, we describe how this novel neural engineering approach may be used to produce a nervous tissue interface to integrate disconnected motor and sensory functions for external control. METHODS: For nervous system repair, we recently developed a unique method to engineer nervous tissue constructs in vitro consisting of bundles of axons spanning two populations of neuronal somata. To integrate electronics and nervous tissue to transform electrophysiological signals into electronic signals, we have designed a nervous tissue interface. RESULTS: Our nervous tissue interface consists of stretch-grown nervous tissue with one end interfaced with a multiple electrode array, enabling us to detect and record real-time efferent signals conducted down the nerve and stimulate afferent sensory signaling. CONCLUSION: Our ultimate goal is to develop a neurally controlled prosthesis and a nervous system interface that could be linked to the patient's thoughts, providing two-way signaling for motor control and feedback from multiple external stimuli.

Axons↗