Intact Peripheral Nerves Research Articles

The effect of peripheral nerve lesions and of neonatal capsaicin in the rat on primary afferent depolarization.

1. In anaesthetized adult rats with intact peripheral nerves, a conditioning orthodromic volley in myelinated afferents produces a prolonged increase in the excitability of the terminals of the afferents which have carried the orthodromic volley and in the terminals of their passive neighbours. This phenomenon, primary afferent depolarization, p.a.d., is shown by the antidromic stimulation of afferents with a micro-electrode in the dorsal horn and by recording the antidromic volley on a cut peripheral nerve.2. If a peripheral nerve is cut and ligated, the size of the myelinated afferent volley generated by stimulation proximal to the cut and measured on dorsal roots is not affected for 14 days after the cut (Wall & Devor, 1981). Similarly the size of the volleys ascending the cord in axons from cord cells remains unaffected.3. If a peripheral nerve is cut and tested after 7-14 days, it produces a markedly decreased p.a.d. on itself and on its neighbours.4. If a nerve is crushed rather than cut, it produces a normal p.a.d. on itself and its neighbours after 7-14 days.5. In animals treated neonatally with capsaicin, there is a severe loss of unmyelinated afferents. Testing the effect of an orthodromic volley in myelinated afferents on the excitability of myelinated afferent central terminals shows that there is a strongly decreased p.a.d. in these animals.6. It is concluded that primary afferent depolarization is sensitive to peripheral nerve lesions and that it may be particularly dependent on the integrity of the unmyelinated afferents in spite of the fact that p.a.d. is measured as a phenomenon of myelinated afferents acting on myelinated afferents.

Nonidet P40 and the retrograde transport of horseradish peroxidase in undamaged visceral nerves

ROGERS, R. C., L. A. LIHOLTZ AND E. M. EBLY. Nonidet P40 and the retrograde transport of horseradish peroxidase in undamaged visceral nerves. BRAIN RES. BULL. 8(6) 775–776, 1982.—The cell bodies of origin of peripheral nerves, in particular visceral nerves, are often difficult to identify using standard horseradish peroxidase (HRP) methods. The non-ionic surfactant Nonidet-P40, when applied to intact peripheral nerve along with HRP, allows the investigator to examine the neurons of origin of the nerve without cutting the fibers or injecting label into its peripheral terminal field.

Computerized Signature Discrimination of Above-Lesion EMG to Activate Functional Electrical Stimulation of Peripheral Lower Extremity Nerves of Complete Paraplegics

The paper describes first patient results for a microcomputer based signature discrimination of raw EMC obtained by surface electrodes located at the erector spinae above the level of the lesion of a T-6 and of a T-10 spinal cord complete lesion (total) paraplegic. It is shown that 4 distinct and re-peatable signatures can be easily discriminated to activate all 4 basic functions (stand up, sit down, right-leg-up-then-down, left-leg-up-then-down) of primitive walking as produced by functional electrical stimulation (FES) of the intact peripheral nerves of the patient's lower extremities. The EMC signatures are each generated when the patient produces with his trunk above the lesion the phantom movement that would have produced the corresponding lower-extremity function of a non-paraplegic. Total activation delay is of 0.3 seconds, using a Motorola 68000 microprocessor. Signature discrimination is via comparing the parameters of a 4'th order pure-autoregressive statistical model of the raw EMC's time series, and its sample variance, this model being the one whose error relative to the true signal is white noise and hence free of linearly-retrievable information.The EMC signature discrimination system above has been interfaced with Dr. Kralj's FES system. Presently, the stand-up and sit-down functions have been successfully and repeatedly executed by one of the patients above via the EMC signature discrimination command of the FES system.

Mouse somatosensory cortex: Alterations in the barrelfield following receptor injury at different early postnatal ages

The destruction of a row—row C—of follicles of the mystacial vibrissae in 106 mice during early postnatal life caused alterations of the barrels in the contralateral first somatosensory area of the cortex that corresponded to the lesioned sites. It is to be noted that barrel neurones are placed three synapses away from the periphery. Destruction of follicles on postnatal day 0 to 6 inclusive produced alterations of corresponding barrels in the cerebral hemispheres of the animals killed when 12 days old. This suggests that in the development of the somatosensory system of the mouse there is a critical period, during which peripheral insult leads to abnormal cytoarchitectonic cortical patterns. These patterns varied and were categorised, a given type being predominant for a given day of lesion. After lesions on postnatal day 0, a narrow, elongated barrel-like territory occupies the lesion-related domain. After lesions on postnatal day 1, this domain is reduced to an elongated island of cells in disarray, or is absent (barrelless territory). Lesions on postnatal day 2 caused a pattern that is transitional between the barrel less territory and the poorly defined barrels, which are predominant following lesions on postnatal day 3. Lesions on days 4, 5 or 6 produced (abnormally) sharply defined barrels. Whereas all previous modifications were confined to the hemisphere contralateral to the lesion, the last lesion-group displayed enlarged septa in both hemispheres. Wherever the lesion-related domain occupies an area smaller than the normal barrel row which it replaces, the adjacent rows ‘fill in’. Surface area measurements and statistical analysis allowed us to make the following point: (i) After lesions from day 0 to day 3 the surface area of the cortical lesion-related domain was reduced; it was only after lesions on days 2 and 3 that the increase in area of the neighbouring rows offset this reduction. (ii) Alterations due to lesions from birth to day 6 do not follow a gradual progression toward normal, as described by others. Indeed, the greatest reduction of the lesion-related domain was found following lesions on day 1 and not day 0. (iii) Following lesions on days 4, 5 or 6, an increase in area of the lesion-related septa corresponded to a reduction in area of the lesion-related barrels. Tentative interpretations of our findings include collateral sprouting of intact peripheral sensory nerve fibres, degeneration of neurones whose peripheral, sensory terminals have been destroyed, peripheral and central regeneration of lesioned Gasserian neurones, a modified balance in the competition of the terminals for postsynaptic space, atrophy of neurones that receive a decreasing number of terminals or impulses, loss of the remodelling capacity of a centre after its invasion by synapses, stabilisation of early exuberantly distributed callosal terminals, and an altered parcellation of the thalamocortical fibres from the onset of their ingrowth into the cortex.

Causes of erectile dysfunction

Normal male erection depends upon a combination of factors including normal cortico-sensory perception, intact spinal pathways, normal parasympathetic and sympathetic peripheral nerve innervation, normal blood supply, both arterial and venous to the penis and normal corpora cavernosa. It is obvious, therefore, that disturbances in any of the above components might result in loss of erectile function. It is useful for the clinician to try to identify the cause of erectile function in a particular patient. While these basic anatomic pathways are the prerequisite for normal male sexual function, they in turn depend upon specific hormonal and biochemical support for their integrity.

Hypoglossal-Facial Nerve Anastomosis for Reinnervation of the Paralyzed Face

The hypoglossal-facial nerve crossover is a valuable surgical procedure for the treatment of certain types of facial paralysis. It is most effective when used as an integral part of a primary ablative operation for the treatment of cancer in this region. In the treatment of long-standing facial paralysis, its application requires an intact peripheral facial nerve system and some functioning mimetic muscles with an obliterated proximal facial nerve segment. It is recognized that other procedures are available for repair in patients who meet essentially these same criteria. The disadvantages are minimal intraoral crippling, mass movements of the face and, in some instances, hypertonia of the face. The advantages are improved facial tone, protection of the eye, intentional facial movements controlled by the tongue, and movements associated with physiological functions of the tongue.

Distribution of ultrastructural tracers in crustacean axons.

Ruthenium red and horseradish peroxidase were used to compare the uptake of exogenous molecules into crayfish motor axons and their sheaths in severed and intact peripheral nerves. Both tracers penetrated the axonal sheath and were subsequently seen lining small vesicles and tubules in the axoplasm. Tracer appeared to enter the axon via pinocytotic vesicles. There were no perceptible quantitative or qualitative differences in ruthenium red uptake between intact and severed axons. However, counts of tracer-filled vesicles in axons exposed to peroxidase showed that at least three times as much tracer penetrated the severed as opposed to the intact axons.

Depletion of brain amines reverses blood pressure response to footshock in rat.

WHEN unavoidable electric footshocks are delivered to two rats in an enclosure, they engage in species-specific stereotyped fighting behaviour1, and a significant decrease in tail blood pressure ensues2. Conversely, when the same shocks are delivered to single rats alone in the cage, only disorganized escape behaviour is displayed and a significant increase in blood pressure ensues2. The reversal of the blood pressure response to shock in pairs, from a significant decrease to a significant increase, produced by intravenous 6-hydroxydopa-mine (6-OHDA) indicated the need for intact peripheral sympathetic nerve terminals for blood pressure to decrease after shock-induced fighting (our work in preparation). We report here an investigation of the role of central nervous system (CNS) catecholamines, using intracisternally administered 6-OHDA.

An investigation of the nerve supply to thealt gland of the duck.

Secretion can be produced from the salt gland of the duck by electrical stimulation of nerves reaching the gland and by the administration of parasympathomimetic drugs; the latency of this response is similar to that of the secretory response produced by intravenous salt loading and is similarly inhibited by atropine. The salt gland contains both acetyl‐ and butyrylcholinesterase; the former appears to be associated with nerve fibres which originate in cells occurring along the gland's secretory nerve and in its ganglion. There is no obvious difference in cholinesterase content of secreting and resting glands. Denervation of the salt gland, by an operation which includes removal of the ganglionic portion of the secretory nerve, abolishes secretory response to salt load and leads to disappearance of cholinesterase. Such denervated glands may be caused to secrete by administration of carbachol; this response is potentiated by concurrent salt loading. Section of the secretory nerve central to its ganglionic region, however, fails to abolish secretion in response to salt loading and does not alter cholinesterase content. Hexamethonium in large doses fails to influence the establishment or course of a secretory response to salt loading. These findings, coupled with the demonstration that cholinesterase staining in the secretory nerve is only seen in and distal to its ganglion cells, suggests that the cholinergic nerve supply to the gland is unusual. The findings support the concept that a cholinergic secretomotor mechanism can produce salt gland secretion. They also imply that any associated hormonal control of secretion cannot operate in the absence of intact peripheral nerve supply. The possibility is discussed that the ganglion cells of the secretory nerve may have an osmoreceptive function.

Activity from skin mechanoreceptors recorded percutaneously in awake human subjects

A technique is described which allows recording of multi-fiber discharge and single-unit activity from intact peripheral nerves of awake human subjects. A tungsten electrode with a tip diameter of 5–15 μ was driven manually through skin, subcutaneous tissues and nerve sheath. From many recording sites in mixed nerve trunks neural impulses with an amplitude of 40 μv were recorded in response to peripheral mechanical stimuli. It was possible to judge when afferent nerve fibers of cutaneous origin lay close to the electrode tip by the quality of the insertion paresthesias and the type of peripheral stimuli required to induce afferent responses. Examples are presented of fast and slowly adapting mass discharge induced by mechanical stimuli on glabrous and nonglabrous skin areas. When single-unit activity was discriminated it was often possible to determine the site of the cutaneous end organ, the discharge characteristics of the unit, and the conduction velocity of the nerve fiber. Ten such single-unit recordings are described.

LIPID CLASS AND FATTY ACID COMPOSITION OF INTACT PERIPHERAL NERVE AND DURING WALLERIAN DEGENERATION.

AbstractLipid extracts from normal cat, chicken, and beef sciatic nerve were fractionated into their components by combinations of silicic acid, Florisil, DEAE‐cellulose, or silicic acid‐silicate column chromatography.The constitutent fatty acids of total lipid extracts and of individual lipid classes were qualitatively and quantitatively determined as their methyl esters by gas chromatography.These methods were also applied to lipid extracts from cat sciatic nerve undergoing Wallerian degeneration at 8, 16, 32, and 96 days after section and to chicken sciatic nerve undergoing demyelination due to organophosphate poisoning.All fatty acids were markedly decreased in the total lipids of cat sciatic nerve at 96 days after section and most of these were decreased at 32 days. As early as 8 days after section 16:0, 16:1, 18:2, 20:0, and 20:4 showed decreases, while 18:0, 18:1, 22:1, 22:5, 22:6, and 24:1 did not begin to show decreases until 16 days after section. The decreases in fatty acids were considered to be due to increased catabolism, decreased synthesis, or increased removal of fatty acids from nervous tissue. The fatty acid content of the total lipids of chicken nerve undergoing demyelination resembled that of cat sciatic nerve between 16 and 32 days after section.Myelin lipids, sphingomyelin, cerebrosides, and phosphatidyl ethanolamine (PE) began to decrease as early as 8 days after section in cat sciatic nerve. Phosphatidyl serine (PS) also decreased at this time. Cholesterol, lecithin, and ethanolamine plasmalogen did not begin to decrease until 16 days after section and phosphatidyl inositol (PI) did not decrease until 32 days after section. Triglycerides decreased markedly at 8 days after section gradually returning to normal by 96 days. This was accompanied by a transient increase in free fatty acids and monoglycerides. Cholesterol esters and lysolecithin increased markedly at 8 days after section and were higher than normal levels even at 96 days after section.In chicken sciatic nerve undergoing demyelination after organophosphate poisoning, cerebroside was the only myelin lipid which decreased in amt, while cholesterol esters and diglycerides increased.Sphingomyelin and cerebrosides containing 16:0, 18:0, 18:1, 18:2, 20:0, 22:0, 23:0, 24:0, 24:1 seemed to be most susceptible to degradation or interference in synthesis in degenerating nerve. For the most part, these fatty acids were observed to increase in cholesterol esters, free fatty acids, and, in some instances, triglycerides.The changes in various lipid classes and their constituent fatty acids are discussed in relation to various cellular changes which accompany degeneration.

SENSORY RECEPTION IN HYSTERICAL ANESTHESIA AS MEASURED BY THE COLD PRESSOR RESPONSE

The paradox of hysterical anesthesia consists of failure to perceive sensory stimuli despite intact and functioning innervation. The preservation of deep and superficial reflexes and the nonanatomic distribution of the anesthesia furnish evidence of the neurologic integrity of the affected parts. The psychodynamic features reveal the conversion nature of the symptoms. The cold pressor test consists of a standard cold stimulus applied to an extremity as a procedure for quantitative estimation of the reactivity of the vasomotor system. 1 The response consists of an increase in systemic blood pressure on immersion of a limb in cold water. It has been demonstrated previously that the cold pressor response depends on the transmission of sensation through intact peripheral nerves. 2 This study was undertaken to determine whether conscious perception of the stimulus is necessary to cause an elevation of blood pressure, or whether the reaction is the result of reflexes mediated at