The effect of succinylcholine on cat gastrocnemius muscle spindle afferents of different types.

Taylor, Anthony R.; Rodgers, J F; Fowle, A J; Durbaba, Rade

doi:10.1113/jphysiol.1992.sp019357

Cited by 44 publications

(46 citation statements)

References 15 publications

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“…We classified units whose dynamic response was greatly increased by suxamethonium as spindle primary afferents. This is a reasonably secure criterion (Taylor, Rodgers, Fowle & Durbaba, 1992). However, Taylor et al (1992) have shown that about half of the gastrocnemius spindles whose resting discharge is increased by suxamethonium, but whose dynamic response is not appreciably affected (i.e.…”

Section: Chronic Recordingsmentioning

confidence: 99%

“…This is a reasonably secure criterion (Taylor, Rodgers, Fowle & Durbaba, 1992). However, Taylor et al (1992) have shown that about half of the gastrocnemius spindles whose resting discharge is increased by suxamethonium, but whose dynamic response is not appreciably affected (i.e. units we would classify as spindle secondaries), have conduction velocities in the spindle primary afferent range.…”

Section: Chronic Recordingsmentioning

confidence: 99%

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Models of ensemble firing of muscle spindle afferents recorded during normal locomotion in cats

Procházka

Gorassini

1998

The Journal of Physiology

147

146

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In spite of many years of research there is still much uncertainty regarding the nature of proprioceptive signals and the role of these signals in kinaesthesia and movement control. The uncertainty mainly concerns the firing characteristics of the most numerous proprioceptors, the muscle spindles. From many studies in anaesthetized animals it is known that mammalian muscle spindle afferents respond to muscle displacement and velocity and that these responses are strongly modulated by ã_fusimotor activity emanating from the central nervous system. Fusimotor action not only increases the firing rate of spindle afferents at a given muscle length ('bias'), it also controls the sensitivity of the afferents to changes in muscle length ('gain'). Just how the mammalian nervous system controls fusimotor action in daily life remains the subject of controversy (for review, see Prochazka, 1996). The firing rate of muscle spindles can also be affected by mechanical factors such as tendon strain, changes in pennation angle, Journal of Physiology (1998) 1. The aim of this work was to compare the ability of several mathematical models to predict the firing characteristics of muscle spindle primary afferents recorded chronically during normal stepping in cats. 2. Ensemble firing profiles of nine hamstring spindle primary (presumed group Ia) afferents were compiled from stored data from 132 step cycles. Three sets of profiles corresponding to slow, medium and fast steps were generated by averaging groups of step cycles aligned to peak muscle length in each cycle. 3. Five models obtained from the literature were compared. Each of these models was used to predict the spindle firing profiles from the averaged muscle length signals. The models were also used in the reverse direction, namely to predict muscle length from the firing profiles. A sixth model incorporating some key aspects of the other models was also included in the comparisons. 4. Five of the models predicted spindle firing well, with root mean square (r.m.s.) errors lower than 14% of the modulation depth of the target profiles. The key variable in achieving good predictions was muscle velocity, the best fits being obtained with power-law functions of velocity, with an exponent of 0·5 or 0·6 (i.e. spindle firing rate is approximately proportional to the square root of muscle velocity). The fits were slightly improved by adding small components of EMG signal to mimic fusimotor action linked to muscle activation. The modest relative size of EMG-linked fusimotor action may be related to the fact that hamstring muscles are not strongly recruited in stepping. 5. Length was predicted very accurately from firing profiles with the inverse of the above models, indicating that the nervous system could in principle process spindle firing in a relatively simple way to give accurate information on muscle length. 6. The responses of the models to standard ramp-and-hold displacements at 10 mm s¢ were also studied (i.e. velocities that were an order of magnitude lower than that during ...

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Section: Chronic Recordingsmentioning

confidence: 99%

Section: Chronic Recordingsmentioning

confidence: 99%

Models of ensemble firing of muscle spindle afferents recorded during normal locomotion in cats

Procházka

Gorassini

1998

The Journal of Physiology

147

146

View full text Add to dashboard Cite

show abstract

“…3D). Measures of increments in initial frequency and dynamic difference (peak frequency minus initial frequency) after SCh were taken as indices of effects exerted through static and dynamic primary spindle afferents, respectively (for a detailed description, see Taylor et al, 1992;Durbaba et al, 2006). In so doing, six neurons were considered to be affected by static bag2 primary spindle afferents, four cells by static/dynamic (bag1/ bag2) primaries, and two neurons by dynamic bag1 primary spindle afferents.…”

Section: Characterization Of Proprioceptive Neuronsmentioning

confidence: 99%

Processing Afferent Proprioceptive Information at the Main Cuneate Nucleus of Anesthetized Cats

Leiras¹,

Velo²,

Martín-Cora³

et al. 2010

J. Neurosci.

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Medial lemniscal activity decreases before and during movement, suggesting prethalamic modulation, but the underlying mechanisms are largely unknown. Here we studied the mechanisms underlying proprioceptive transmission at the midventral cuneate nucleus (mvCN) of anesthetized cats using standard extracellular recordings combined with electrical stimulation and microiontophoresis. Dual simultaneous recordings from mvCN and rostroventral cuneate (rvCN) proprioceptive neurons demonstrated that microstimulation through the rvCN recording electrode induced dual effects on mvCN projection cells: potentiation when both neurons had excitatory receptive fields in muscles acting at the same joint, and inhibition when rvCN and mvCN cells had receptive fields located in different joints. GABA and/or glycine consistently abolished mvCN spontaneous and sensory-evoked activity, an effect reversed by bicuculline and strychnine, respectively; and immunohistochemistry data revealed that cells possessing strychnine-sensitive glycine receptors were uniformly distributed throughout the cuneate nucleus. It was also found that proprioceptive mvCN projection cells sent ipsilateral collaterals to the nucleus reticularis gigantocellularis and the mesencephalic locomotor region, and had slower antidromic conduction speeds than cutaneous fibers from the more dorsally located cluster region.The data suggest that (1) the rvCN-mvCM network is functionally related to joints rather than to single muscles producing an overall potentiation of proprioceptive feedback from a moving forelimb joint while inhibiting, through GABAergic and glycinergic interneurons, deep muscular feedback from other forelimb joints; and (2) mvCN projection cells collateralizing to or through the ipsilateral reticular formation allow for bilateral spreading of ascending proprioceptive feedback information.

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“…In primary afferents this procedure seems to enhance the rapid adaptation phase, which is thought to be due to a property of the ending rather than of the intrafusal muscle fibres. This matter is considered further in the following paper (Taylor, Rodgers, Fowle & Durbaba, 1992).…”

mentioning

confidence: 99%

The classification of afferents from muscle spindles of the jaw‐closing muscles of the cat.

Taylor¹,

Durbaba²,

Rodgers³

1992

The Journal of Physiology

Self Cite

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SUMMARY1. The effects of the muscle-depolarizing drug succinylcholine (SCh) on the stretch responses of jaw-closer muscle spindle afferents were studied in the anaesthetized cat. Using ramp and hold stretches repeated every 6 s the basic measurements made were: initial frequency (IF), peak frequency (PF) and static index (SI), the frequency 0-5 s after the end of the ramp of stretch. Derived from these were: dynamic difference (DD) = PF -IF, dynamic index (DI) = PF -SI and static difference (SD) = SI -IF. Increases in these measures caused by a single i.v. dose of SCh (200 gtg kg-') are symbolized by the prefix A.2. In a population of 234 units, ADD and AIF were each distributed bimodally, but were uncorrelated, thus defining four subgroups.3. ADD was argued to be an index of the effect of bag1 intrafusal fibre contraction and AIF to be an index of the effect of bag2 fibre contraction. On this basis it is proposed that units can be divided into four groups according to the predominant influences of the bag1, bag2 and chain fibres as blc (6-8%), b1b2c (22-2%), b2c (54-3%) or c (16&7%).

show abstract

The effect of succinylcholine on cat gastrocnemius muscle spindle afferents of different types.

Cited by 44 publications

References 15 publications

Models of ensemble firing of muscle spindle afferents recorded during normal locomotion in cats

Models of ensemble firing of muscle spindle afferents recorded during normal locomotion in cats

Processing Afferent Proprioceptive Information at the Main Cuneate Nucleus of Anesthetized Cats

The classification of afferents from muscle spindles of the jaw‐closing muscles of the cat.

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