Scaling factor relating conduction velocity and diameter for myelinated afferent nerve fibres in the cat hind limb.

Boyd, I. A.; Kalu, K. U.

doi:10.1113/jphysiol.1979.sp012737

Cited by 189 publications

(135 citation statements)

References 16 publications

(16 reference statements)

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“…Primary afferents can be loosely segregated into separate populations based on their axonal diameters and corresponding conduction velocities, though those populations have some overlap [18][19][20]. In the cat, Group I proprioceptive afferents, which are sensitive to muscle length, stretch velocity, and force, typically have conduction velocities between 75 and 120 m s −1 , while Group II proprioceptive afferents, which are sensitive primarily to muscle length, typically have conduction velocities ranging from 33 to 60 m s −1 [18,19]. For Aβ cutaneous afferents, conduction velocities typically range between 45 and 80 m s −1 [20].…”

Section: Measurement Of Conduction Velocity and Fiber Typementioning

confidence: 99%

Chronic recruitment of primary afferent neurons by microstimulation in the feline dorsal root ganglia

et al. 2014

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Objective. This study describes results of primary afferent neural microstimulation experiments using microelectrode arrays implanted chronically in the lumbar dorsal root ganglia (DRG) of four cats. The goal was to test the stability and selectivity of these microelectrode arrays as a potential interface for restoration of somatosensory feedback after damage to the nervous system such as amputation. Approach. A five-contact nerve-cuff electrode implanted on the sciatic nerve was used to record the antidromic compound action potential response to DRG microstimulation (2–15 µA biphasic pulses, 200 µs cathodal pulse width), and the threshold for eliciting a response was tracked over time. Recorded responses were segregated based on conduction velocity to determine thresholds for recruiting Group I and Group II/Aβ primary afferent fibers. Main results. Thresholds were initially low (5.1 ± 2.3 µA for Group I and 6.3 ± 2.0 µA for Group II/Aβ) and increased over time. Additionally the number of electrodes with thresholds less than or equal to 15 µA decreased over time. Approximately 12% of tested electrodes continued to elicit responses at 15 µA up to 26 weeks after implantation. Higher stimulation intensities (up to 30 µA) were tested in one cat at 23 weeks post-implantation yielding responses on over 20 additional electrodes. Within the first six weeks after implantation, approximately equal numbers of electrodes elicited only Group I or Group II/Aβ responses at threshold, but the relative proportion of Group II/Aβ responses decreased over time. Significance. These results suggest that it is possible to activate Group I or Group II/Aβ primary afferent fibers in isolation with penetrating microelectrode arrays implanted in the DRG, and that those responses can be elicited up to 26 weeks after implantation, although it may be difficult to achieve a consistent response day-to-day with currently available electrode technology. The DRG are compelling targets for sensory neuroprostheses with potential to achieve recruitment of a range of sensory fiber types over multiple months after implantation.

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Section: Measurement Of Conduction Velocity and Fiber Typementioning

confidence: 99%

Chronic recruitment of primary afferent neurons by microstimulation in the feline dorsal root ganglia

et al. 2014

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“…The left hind limb of two cats was chronically de-afferentated and that of two further cats de-efferentated, and the limbs were perfusion-fixed with glutaraldehyde, as described by Boyd & Kalu (1979). Details of the preparation of material for electron microscopical study of every fibre in each nerve, using the one-hole mount technique of Arbuthnott (1974), were given by Arbuthnott, Ballard, Boyd & Kalu (1980).…”

Section: Methodsmentioning

confidence: 99%

“…The scaling factor for different functional groups in chronically de-afferentated or de-efferentated nerves in the cat was subsequently shown to be [5][6][7] for group I afferent fibres and ax efferent fibres, but considerably less, 4-6 in fact, for group II and III afferents and for y efferents (Boyd, 1964(Boyd, , 1965Boyd & Davey, 1968;Boyd & Kalu, 1979). Not only was the factor different for large and small fibres, but it did not increase progressively with fibre diameter.…”

Section: Introductionmentioning

confidence: 99%

Ultrastructural dimensions of myelinated peripheral nerve fibres in the cat and their relation to conduction velocity

Arbuthnott

Boyd

Kalu

1980

The Journal of Physiology

160

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SUMMARY1. The ultrastructure of all the afferent fibres, or all the efferent fibres, was studied in selected nerves from chronically de-afferentated or de-efferentated cat hind limbs perfusion-fixed with glutaraldehyde.2. The following parameters were measured: number of lamellae in the myelin sheath (n), axon perimeter (s), external fibre perimeter (S), axon cross-sectional area (A). Fibres were allocated to afferent groups I, II, III or efferent groups a and y according to the number of lamellae in the myelin sheath.3. of axon so that m = 2-58 log10 s -1t73. The interpretation that there are two separate linear relations for large and small fibres is favoured. 6. The ratio of axon to external fibre perimeter (g) falls from about 0 70 for group III and small y fibres in the cat to about 0-62 for group II and large y fibres and then rises again to 0'70, or even 0-75 for group I and a axons. (Hursh, 1939;Lubinska, 1960; Coppin, 1973) and between I and 0 (Coppin & Jack, 1972).8. From the theoretical analyses of Rushton (1951) and others 0 should be proportional to the external dimensions of the fibre rather than to axon size. It is shown

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“…This distrib u tion can be directly related to the diam eter distri b utio n since the relation between fiber diam eter and velocity is roughly a p ro p o rtio n al o n e . 3,8,10 These studies usually pertain to the m ain com plex o f the CAP, being associated with the fast conduct in g fibers in the nerve (conduction velocity, C V > 25 m/s). T he estimation procedure introduced by Schoonhoven et a l.14 a n d Stegem an et al 17 ac counts for the thick and fast (25-70 m/s; 5-14 \xm) as well as the th in an d slow (< 2 5 m/s; < 5 jxm) m yelinated fiber group.…”

mentioning

confidence: 99%

Conduction velocity distributions compared to fiber size distributions in normal human sural nerve

et al. 1995

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Compound action potentials (CAPs) were recorded from the sural nerve of healthy volunteers. A mathematical technique (inverse modeling) was used to compute conduction velocity (CV) histograms from the data. Results were compared to the morphology of age-matched nor mal sural nerve biopsies. Coefficients of variation (CoVs) revealed the statistical relationship between morphological data (diameter histo grams) and electrophysiological data (CV histograms and conventional CAP parameters). No differences were found for the thick fiber group when comparing the CoVs of the diameter histogram parameters with the corresponding CV histogram parameters. Apparently, the same in herent biological interindividual variability is encountered. The CoVs of the CVs of the CAP'S main phases are in good agreement with the CoVs of the estimated mean velocity of the thick fiber group. Inverse model ing increases the reliability of the estimation of the number of active fibers as compared to direct CAP amplitude interpretation.

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Scaling factor relating conduction velocity and diameter for myelinated afferent nerve fibres in the cat hind limb.

Cited by 189 publications

References 16 publications

Chronic recruitment of primary afferent neurons by microstimulation in the feline dorsal root ganglia

Chronic recruitment of primary afferent neurons by microstimulation in the feline dorsal root ganglia

Ultrastructural dimensions of myelinated peripheral nerve fibres in the cat and their relation to conduction velocity

Conduction velocity distributions compared to fiber size distributions in normal human sural nerve

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