The effects of injury on mammalian nerve fibres

Abstract

When a nerve is removed from a frog and connected with an amplifier and recording system, occasional impulses appear if the fibres are allowed to dry and a short discharge can be produced by pinching or cutting, but if drying is prevented there is no sign of activity except during the actual infliction of an injury. Mammalian nerves give a very different picture. In a mediumsized nerve trunk from the cat or rabbit, set up in a moist, warm atmosphere, large and rapid fluctuations of potential are nearly always present and the disturbance may last for an hour or more in spite of repeated irrigation. Very small nerves may give a steady base line and in nerves prepared for recording motor or sensory discharges a disturbance, initially present, may subside during the exposure and manipulation, but in all mammalian experiments the danger of an unsteady background is increasingly present as the condition of the nerve is a closer and closer approach to the normal.

Electrical Responses From the Lateral-Line Nerves of Fishes

“…It is similar in many respects to that described by Adrian (1930) from injured mammalian nerve fibers. That the neuromasts discharge impulses independently of injury may be demonstrated by slicing along the flank between the region of exit of the nerve to the electrodes and the tail.…”

“…The fact that the non-spontaneously discharging tactile receptors fail to respond in all preparations when the spontaneous discharge set up by the neuromasts fails, suggests the dependence of excitabilities of both groups of receptors on essentially similar steady metabolic conditions. Adrian (1930) found that rhythmicity of impulses discharged from injured mammalian nerve fibers at body temperature does not occur at frequencies of less than 150 per second. When the frequency declines below that the discharge becomes aperiodic.…”

“…This continuous action was found to set up rhythmic discharges of impulses over the acid-immersed wire outside of the tube as fast as it recovered from the refractory period following each impulse. Adrian (1930) described types of repetitive and rhythmic discharges of impulses arising from injured mammalian nerve fibers. He found that when several injured fibers were discharging repetitively the impulses may become synchronized, and he concluded that the synchronization is probably due to the superimposed stimulating effect of action currents of one fiber on its neighbors.…”

Afferent impulses in the carotid sinus nerve (nerve of hering) during asphyxia and anoxæmia

“…With the above experimental conditions the possibility that the asphysial discharges represented an irregular activity of the stretch receptors in the sense described by Matthews [1933] for the nerveendings of mammalian muscle was definitely excluded. Moreover the peripheral ends of the cut fibres (from the stretch receptors) were, of course, superficially placed, practically in contact with air, and it seems difficult to believe that the asphyxia or lack of oxygen of the circulating blood might have caused them to give injury impulses [see Adrian, 1930]. Besides, the dropping of warm Ringer on the preparation had no evident effect on the discharge.…”

Muscle Pain and Muscle Spindles

“…It was not considered, that an ectopic nerve potential spreads to both directions from the site of its origin [8] and thus a motor unit potential (MUP) or fasciculation potential should be recorded, not an EPS [9]. In addition, experimental studies do not support the hypothesis that irregular sustained action potentials like EPSs be activated by peripheral nerve injury or irritation [10][11][12]. To discuss the origin of EPSs, we have to look at the physiological properties of the muscle spindle.…”