Reticulospinal inhibition of interneurones

Engberg, I.; Lundberg, A.; Ryall, R. W.

doi:10.1113/jphysiol.1968.sp008403

Cited by 136 publications

(15 citation statements)

References 10 publications

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“…17 The inhibition of FRA pathways was caused by the inhibition of first order interneurons. 18 In contrast, the ventral reticulospinal tract described in this study possibly inhibited FRA pathways at the level of the last order interneurons and excited a group of Ib inhibitory interneurons.…”

contrasting

confidence: 60%

Medullary reticulospinal tract mediating the generalized motor inhibition in cats: Parallel inhibitory mechanisms acting on motoneurons and on interneuronal transmission in reflex pathways

Takakusaki¹,

Kohyama²,

Matsuyama³

et al. 2001

Neuroscience

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contrasting

confidence: 60%

Medullary reticulospinal tract mediating the generalized motor inhibition in cats: Parallel inhibitory mechanisms acting on motoneurons and on interneuronal transmission in reflex pathways

Takakusaki¹,

Kohyama²,

Matsuyama³

et al. 2001

Neuroscience

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“…In deciding upon the lesions we were guided by the knowledge that the tonic decerebrate control of transmission from the FRA is mediated by pathways descending in the dorsal part of the lateral funicles and that a bilateral effect is exerted from the descending pathway in either spinal half (Holmqvist & Lundberg, 1959). Evidence that stimulation of the brain stem may evoke, selectively, descending effects via the dorsal reticulospinal system is provided not only by the finding that inhibition is produced in the absence of any effect to motoneurones and primary afferents but also by a very selective action on interneurones (Engberg, Lundberg & Ryall, 1966) which will be discussed in a separate paper.…”

Section: Discussionmentioning

confidence: 99%

Reticulospinal inhibition of transmission in reflex pathways

Engberg¹,

Lundberg²,

Ryall³

1968

The Journal of Physiology

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222

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SUMMARY1. The effect of electrical stimulation of the brain stem on reflex transmission has been investigated in decerebrate cats after partial transection of the spinal cord.2. Brain stem stimuli that do not evoke inhibitory post-synaptic potentials (IPSPs) in motoneurones or primary afferent depolarization may still effectively depress the excitatory and inhibitory synaptic actions evoked from the flexor reflex afferents (FRA) and from lb afferents. There is no effect on post-synaptic potentials from Ia afferents or on Renshaw IPSPs. The depression is not associated with any measurable change in conductance over the motoneuronal membrane.3. There is also inhibition from the brain stem of transmission from the FRA (but not from Ia and Ib afferents) to primary afferqnt terminals and to ascending spinal pathways. 4. It is concluded that this inhibition from the brain stem is exerted at an interneuronal level in spinal reflex paths.5. The inhibitory action is evoked from the region ofMagoun's inhibitory centres in the brain stem and is mediated by axons with a conduction velocity of at least 20 m/sec. The axons are distributed in the dorsal part of the lateral funicle.6. The pathway mediating the inhibition from the brain stem is named the dorsal reticulospinal system. Its possible role in maintaining the decerebrate control of reflexes is discussed and related to the problem of a selective control of some paths from a primary afferent system.

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“…First, segmental interneuronal pathways, including those responsible for group I b effects toa-motoneurones, are suppressed in the decerebrate preparation (Eccles & Lundberg, 1959). This is partly attributable to the tonic action of the dorsolateral reticulospinal system (Engberg, Lundberg & Ryall, 1968), and in the following paper (Iles et al 1989) are described the effects of lesions which interrupt its action on the lumbosacral spinal cord. These preparations, as well as the 'atypical' one described in the present study, gave higher values for inhibitory feedback gain.…”

Section: Inhibitory Feedback In Intact Preparationsmentioning

confidence: 99%

Autogenetic inhibition from contraction receptors in the decerebrate cat.

Jack¹,

Kullmann²,

Roberts³

1989

The Journal of Physiology

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SUMMARY1. Autogenetic inhibition from contraction receptors was measured by eliciting contractions of the soleus muscle in the decerebrate cat. Inhibitory feedback was detected when the tension increment f, produced by stimulating motor fibres in the presence of a background reflex contraction, was smaller than the tension d elicited by the same stimulus in the absence of reflex action. Tendon vibration was applied throughout to clamp primary spindle afferents at a constant firing rate, thereby preventing spindle unloading from disfacilitating the reflex contraction.2. The reduction in tension d-f varied roughly linearly with the size of the tension stimulus f. Feedback gain was proportional to d-f/f, i.e. the ratio of inhibited tension to stimulus tension. It was computed by averaging over several measurements obtained with stimuli of different sizes, and ranged between 0 and 0-88 in ten animals. The average gain, 0 39, implies that voluntary muscle force is reduced by approximately 27 % through the direct inhibition of a-motoneurones from homonymous contraction receptors.3. Inhibitory feedback gain did not appear to co-vary with the background reflex contraction. When measured without vibration, however, a positive covariance did emerge, suggesting that this is due to unloading of muscle spindles, either by extrafusal muscle shortening or by inhibition of fusimotor neurones.4. Inhibited tension varied linearly with the estimated increment in Ib afferent firing. On the assumption that group I b afferents carried the entire inhibitory signal, inhibitory feedback gain measured with vibration was used to predict the size of the gain if vibration had not been applied. Feedback gain calculated in this way was reduced by still did not vary with reflex tension.5. In one animal with signs of brain stem trauma, feedback gain was increased to around six. It is argued that inhibitory feedback in the intact animal can rise to comparable values, as a result both of convergence of signals from different muscles and of supraspinal facilitation.

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Reticulospinal inhibition of interneurones

Cited by 136 publications

References 10 publications

Medullary reticulospinal tract mediating the generalized motor inhibition in cats: Parallel inhibitory mechanisms acting on motoneurons and on interneuronal transmission in reflex pathways

Medullary reticulospinal tract mediating the generalized motor inhibition in cats: Parallel inhibitory mechanisms acting on motoneurons and on interneuronal transmission in reflex pathways

Reticulospinal inhibition of transmission in reflex pathways

Autogenetic inhibition from contraction receptors in the decerebrate cat.

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