Some Properties of the Cord Potentials Evoked by a Single Afferent Volley

Hughes, Joseph; Gasser, Herbert S.

doi:10.1152/ajplegacy.1934.108.2.295

Cited by 70 publications

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“…Electrical Evidence.--Hughes and Gasser demonstrated in 1934 that the negative intermediary dorsal cord potential showed more rapid spatial decrement than the preceding spike potential when recorded at successively greater distances rostral to the root level of entry of the afferent volley (8). The fact that the slow cord potentials are more closely localized to a few cord segments about the region of root entry than is the spike is particularly striking since the spike potential, because of its short-wave length, will suffer greater reduction in size through temporal dispersion.…”

Section: Preliminary Considerations Theoretical Basis Of a Methods Formentioning

confidence: 99%

After-Potential of Spinal Axons in Vivo

Rudin

Eisenman

1953

Journal of General Physiology

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This investigation is concerned with certain properties of the action potential in tracts of the central nervous system. During the course of other studies (16,3) it became important to know the after-potential sequence of rapidly conducting tract fibers in the intact spinal cord. This paper presents a method for obtaining this information and evidence for the existence in dorsal column axons of an after-potential sequence which is significantly different from that of peripheral nerve A fibers. In succeeding papers (17) the role of the dorsal column after-potential in producing intramedullary and dorsal root current flows is examined. Study of these currents affords an experimental test of predictions which follow directly from the conclusions of the present paper on the form of the dorsal column after-potential. Finally in another paper (3) are presented for comparison the results of a direct examination of the afterpotential sequence of spinal funiculi in vitro. In addition, the findings of a general survey of the properties of spinal funiculi are presented there. TechniqueThe cats (84 in all) used for this and the subsequent study (17) were, as a rule maintained under sodium pentobarbital anesthesia (27 reg./kilo) since suppression of transynaptic neural activity as well as of the dorsal colunm relay potential was desired. Critical experiments were also performed in unanesthetized cats not less than 1 hour following decapitation or decerebration under ether. After laminectomy, mineral oil was layered over roots and cord to a depth of several centimeters and maintained within 0.5 ° C. of rectal temperature (37.5 q-2°C.) by means of radiant heating.Electrodes of bright silver or chlorided silver were used. Monophasic rectangular stimulating pulses (0.1 to 0.5 msec. duration), isolated from ground by Schmitt radio frequency coupling units (Grass) were delivered as constant current through ~ to 1 megohm resistors in series with the preparation. When stimulating pulses were applied through two pairs of electrodes from two independent stimulators the circuits

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Section: Preliminary Considerations Theoretical Basis Of a Methods Formentioning

confidence: 99%

After-Potential of Spinal Axons in Vivo

Rudin

Eisenman

1953

Journal of General Physiology

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“…The field potentials near the dorsal surface of the cord are negative followed by the positive wave [see 148]. The lateral half of the dorsal horn is also negative, whereas most of the ventral horn is electrically positive [149]. The mechanical distortion of the spinal cord followed by release of neurochemicals influence conduction of impulses due to altered synaptic transmission within the cord [44,[150][151][152][153][154][155].…”

Section: Spinal Cord Conduction and Cell Injury Following Scimentioning

confidence: 99%

Pathophysiology of Blood-Spinal Cord Barrier in Traumatic Injury and Repair

Sharma¹

2005

CPD

158

218

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Blood-spinal cord barrier (BSCB) plays an important role in the regulation of the fluid microenvironment of the spinal cord. Trauma to the spinal cord impairs the BSCB permeability to proteins leading to vasogenic edema formation. Several endogenous neurochemical mediators and growth factors contribute to trauma induced BSCB disruption. Studies carried out in our laboratory suggest that those drugs and neurotrophic factors capable to attenuate the BSCB dysfunction following trauma are neuroprotective in nature. Whereas, agents that do not exert any influence on the BSCB disruption failed to reduce cell injury. These observations are in line with the idea that BSCB disruption plays an important role in the pathophysiology of spinal cord injuries. The probable mechanism(s) of trauma induced BSCB dysfunction and its contribution to cell injuries are discussed.

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“…Antidromic stimulation of the ventral root in the mammal does not produce any active signs of nervous activity recordable in DR fibers.3I 13 Figure 3B. The first clear deflection is a positive variation (DR IV of Lloyd and McIntyre'5) immediately followed by an asynchronous discharge, the DR reflex which is observed riding on the beginning of a slowly rising negative wave.…”

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confidence: 94%

An Effect of Postsynaptic Neurons Upon Presynaptic Terminals

Decima

1969

Proc. Natl. Acad. Sci. U.S.A.

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Abstract.-Centrifugal ("antidromic") discharges in cat sensory fibers are observed consistently in a variety of experimental preparations and with many different surgical and recording techniques. As is well known, they can be either "spontaneous" or induced by afferent volleys in other sensory fibers. In addition, it is shown here that they can be elicited by antidromic motoneuron activation when the latter is conditioned by natural sensory stimuli or by shocks to the dorsal roots. The latency of the centrifugal dorsal root response to ventral root stimulation is shorter than that of the monosynaptic reflex mediated by the same fibers. An "antidromic" coupling, probably of an electrical nature, between motoneurons and presynaptic terminals is postulated.The presence of nerve impulses leaving the spinal cord via dorsal roots (centrifugal sensory discharges) was discovered almost 80 years ago'0 and has been repeatedly confirmed by later investigators.2 5,6,9,12,18,19 Nevertheless, in spite of all the evidence encountered, it may be said that at present these discharges are still considered by neurobiologists to be a most uncommon type of sensory fiber activity. Although the reasons for this attitude are varied,1' 11 one of the most important probably is the disturbing nature of the phenomenon vis-A-vis classical neuronal theory. However, even if one does not accept the existence of this type of dorsal root (DR) activity as a normal physiological phenomenon, the question about the mechanism producing it remains perfectly valid.Dorsal root volleys generate a long-lasting depolarization, the dorsal root potential, in the activated as well as in neighboring DR fibers." 15 During the beginning of the depolarization, a mass discharge of "antidromic" sensory impulses, the DR reflex, can often be observed.19 Because of its relation to the DR potential, this type of efferent DR activity has been proposed to be a direct result of the presynaptic depolarization.4' 20 A marked increase in electrical excitability, maximal at the terminals and with a time course similar to the DR potential, has also been found in these afferent fibers.2'Although the concept of depolarization of presynaptic terminals has been linked with presynaptic inhibition, the mechanism by which the DR potential is generated still remains unclear. Eccles7' 8 has proposed a multisynaptic neuronal chain ending in axo-axonic synapses (chemical) on the primary afferent fibers. On the other hand, Barron and Matthews3 proposed that the depolarization that involved both stimulated and adjacent passive fibers was due to the extracellular accumulation of some ionic substance liberated by the excited terminals; some type of ionic interaction would then be present inside the cord.This communication is concerned with some aspects of the centrifugal dis-58

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Some Properties of the Cord Potentials Evoked by a Single Afferent Volley

Cited by 70 publications

References 0 publications

After-Potential of Spinal Axons in Vivo

After-Potential of Spinal Axons in Vivo

Pathophysiology of Blood-Spinal Cord Barrier in Traumatic Injury and Repair

An Effect of Postsynaptic Neurons Upon Presynaptic Terminals

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