Selective cortical and segmental control of primary afferent depolarization of single muscle afferents in the cat spinal cord

1997 ◽  
Vol 113 (3) ◽  
pp. 411-430 ◽  
Author(s):  
J. R. Eguibar ◽  
J. Quevedo ◽  
P. Rudomin
Keyword(s):  
Spinal Cord ◽  
Muscle Afferents ◽  
Primary Afferent Depolarization ◽  
Single Muscle ◽  
Primary Afferent

scholarly journals Muscle afferent excitability testing in spinal root-intact rats: dissociating peripheral afferent and efferent volleys generated by intraspinal microstimulation

2017 ◽  
Vol 117 (2) ◽  
pp. 796-807 ◽  
Author(s):  
Saeka Tomatsu ◽  
Geehee Kim ◽  
Joachim Confais ◽  
Kazuhiko Seki
Keyword(s):  
Spinal Cord ◽  
Presynaptic Inhibition ◽  
Muscle Afferents ◽  
Primary Afferents ◽  
Medial Gastrocnemius ◽  
Primary Afferent Depolarization ◽  
Spinal Root ◽  
Primary Afferent ◽  
Intraspinal Microstimulation ◽  
Spinal Roots

Presynaptic inhibition of the sensory input from the periphery to the spinal cord can be evaluated directly by intra-axonal recording of primary afferent depolarization (PAD) or indirectly by intraspinal microstimulation (excitability testing). Excitability testing is superior for use in normal behaving animals, because this methodology bypasses the technically challenging intra-axonal recording. However, use of excitability testing on the muscle or joint afferent in intact animals presents its own technical challenges. Because these afferents, in many cases, are mixed with motor axons in the peripheral nervous system, it is crucial to dissociate antidromic volleys in the primary afferents from orthodromic volleys in the motor axon, both of which are evoked by intraspinal microstimulation. We have demonstrated in rats that application of a paired stimulation protocol with a short interstimulus interval (ISI) successfully dissociated the antidromic volley in the nerve innervating the medial gastrocnemius muscle. By using a 2-ms ISI, the amplitude of the volleys evoked by the second stimulation was decreased in dorsal root-sectioned rats, but the amplitude did not change or was slightly increased in ventral root-sectioned rats. Excitability testing in rats with intact spinal roots indicated that the putative antidromic volleys exhibited dominant primary afferent depolarization, which was reasonably induced from the more dorsal side of the spinal cord. We concluded that excitability testing with a paired-pulse protocol can be used for studying presynaptic inhibition of somatosensory afferents in animals with intact spinal roots. NEW & NOTEWORTHY Excitability testing of primary afferents has been used to evaluate presynaptic modulation of synaptic transmission in experiments conducted in vivo. However, to apply this method to muscle afferents of animals with intact spinal roots, it is crucial to dissociate antidromic and orthodromic volleys induced by spinal microstimulation. We propose a new method to make this dissociation possible without cutting spinal roots and demonstrate that it facilitates excitability testing of muscle afferents.

γ-Aminobutyric acid and primary afferent depolarization in feline spinal cord

1979 ◽  
Vol 57 (10) ◽  
pp. 1157-1167 ◽  
Author(s):  
B. R. Sastry
Keyword(s):  
Spinal Cord ◽  
Nerve Stimulation ◽  
Muscle Afferents ◽  
Aminobutyric Acid ◽  
Primary Afferent Depolarization ◽  
Antidromic Activation ◽  
Primary Afferent ◽  
Afferent Terminal ◽  
Group I ◽  
Terminal Excitability

The effects of iontophoretically applied γ-aminobutyric acid (GABA), (−)-nipecotic acid (NCA), 2,4-diaminobutyric acid (DABA), and pentobarbital were examined on the thresholds for antidromic activation of single group I muscle afferents, in decerebrated spinal cats. GABA decreased the threshold for antidromic activation of the majority of the afferents. During this decrease in the threshold, the preterminal axons were depolarized. This depolarization was decreased by a prior depolarization, but increased by a hyperpolarization, of the afferent. During the depolarization of the afferent produced by GABA, the size of the orthodromic action potential was decreased. Iontophoretically applied bicuculline antagonized the effect of GABA on the threshold for antidromic activation of the afferents. NCA, DABA, and pentobarbital potentiated the action of GABA on the afferent terminal excitability. Pre-treatment of the animals with semicarbazide, which reportedly depletes spinal GABA, resulted in a reduction in the threshold produced by a conditioning stimulation of other group I afferents. GABA decreased the threshold for antidromic activation of the nonterminal regions of the afferents when applied near the stimulation sites. The amounts of GABA required to produce a decrease in the threshold of the nonterminal afferents were greater than those required to produce a comparable effect on the terminal regions of the fibres. Iontophoretically applied NCA and bicuculline, in amounts that were adequate to alter the effects of applied GABA, failed to affect the nerve stimulation-induced decrease in the threshold for antidromic activation of the fibres. Intravenously injected bicuculline, however, antagonized the actions of GABA as well as of the reduction in the threshold produced by nerve stimulation.These results indicate that (1) GABA-induced increase in the excitability of group I afferent terminals is associated with a depolarization of the afferent, (2) the uptake of iontophoretically applied amino acid into the spinal cord tissue appears to limit its action on the afferent terminal excitability, (3) GABA has a preterminal depolarizing action on group I muscle afferents, and (4) primary afferent depolarization produced by nerve stimulation may be of diffuse origin and, hence, cannot be significantly affected by iontophoretically applied NCA and bicuculline.

Effects of γ-aminobutyrate and bicuculline on primary afferent depolarization of cutaneous fibres in the cat spinal cord

Neuroscience ◽  
1983 ◽  
Vol 10 (3) ◽  
pp. 869-874 ◽  
Author(s):  
G. Gmelin ◽  
M. Zimmermann
Keyword(s):  
Spinal Cord ◽  
Primary Afferent Depolarization ◽  
Primary Afferent

Recurrent potentials in human peripheral sensory nerve: Possible evidence of primary afferent depolarization of the spinal cord

1992 ◽  
Vol 15 (12) ◽  
pp. 1354-1363 ◽  
Author(s):  
Jeremy M. Shefner ◽  
Fritz Buchthal ◽  
Christian Krarup
Keyword(s):  
Spinal Cord ◽  
Sensory Nerve ◽  
Primary Afferent Depolarization ◽  
Primary Afferent ◽  
Peripheral Sensory

Effects of pad on conduction of action potentials within segmental and ascending branches of single muscle afférents in the cat spinal cord

2000 ◽  
Vol 135 (2) ◽  
pp. 204-214 ◽  
Author(s):  
Joel Lomelí ◽  
Luis Castillo ◽  
Pablo Linares ◽  
Pablo Rudomin
Keyword(s):  
Spinal Cord ◽  
Action Potentials ◽  
Muscle Afferents ◽  
Single Muscle

scholarly journals The effects of central myorelaxants on synaptically-evoked primary afferent depolarization in the immature rat spinal cord in vitro

1994 ◽  
Vol 111 (2) ◽  
pp. 497-502 ◽  
Author(s):  
R. J. Siarey ◽  
S.K. Long ◽  
M.T.H. Tulp ◽  
R.H. Evans
Keyword(s):  
Spinal Cord ◽  
Primary Afferent Depolarization ◽  
Rat Spinal Cord ◽  
Primary Afferent ◽  
Immature Rat
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