Postspike facilitation of forelimb muscle activity by primate corticomotoneuronal cells

Fetz, Eberhard E.; Cheney, Paul D.

doi:10.1152/jn.1980.44.4.751

Cited by 672 publications

(332 citation statements)

References 7 publications

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“…For example, if the SC interneurons we recorded were inhibitory cells, their phase-inverted firing relative to excitatory inputs from M1 would produce in-phase summation of activity at the motoneuron. To assess this, we computed spiketriggered averages of EMG (30). Six cells of the SC intermediate zone produced postsynaptic facilitations (PSFs).…”

Section: Resultsmentioning

confidence: 99%

Spinal interneuron circuits reduce approximately 10-Hz movement discontinuities by phase cancellation

Williams

Soteropoulos

Baker

2010

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

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Tremor imposes an important limit to the accuracy of fine movements in healthy individuals and can be a disabling feature of neurological disease. Voluntary slow finger movements are not smooth but are characterized by large discontinuities (i.e., steps) in the tremor frequency range (approximately 10 Hz). Previous studies have shown that these discontinuities are coherent with activity in the primary motor cortex (M1), but that other brain areas are probably also involved. We investigated the contribution of three important subcortical areas in two macaque monkeys trained to perform slow finger movements. Local field potential and singleunit activity were recorded from the deep cerebellar nuclei (DCN), medial pontomedullary reticular formation, and the intermediate zone of the spinal cord (SC). Coherence between LFP and acceleration was significant at 6 to 13 Hz for all areas, confirming the highly distributed nature of the central network responsible for this activity. The coherence phase at 6 to 13 Hz for DCN and pontomedullary reticular formation was similar to our previous results in M1. By contrast, for SC the phase differed from M1 by approximately π rad. Examination of single-unit discharge confirmed that this was a genuine difference in neural spiking and could not be explained by different properties of the local field potential. Convergence of antiphase oscillations from the SC with cortical and subcortical descending inputs will lead to cancellation of approximately 10 Hz oscillations at the motoneuronal level. This could appreciably limit drive to muscle at this frequency, thereby reducing tremor and improving movement precision.T remor is a key limitation to human fine motor performance.However, in tremor research, the puzzle is not so much why our hands shake, but why they often do not. Numerous mechanisms can contribute to unstable contraction: motoneurons are recruited at a fixed frequency, limb segments have mechanical resonance, the monosynaptic stretch reflex arc can produce feedback oscillations, and there are a plethora of central neural oscillators. These factors often converge to produce mechanical oscillations at approximately 10 Hz, the dominant frequency of physiological tremor. Yet despite these multiple sources of instability, in most people, most of the time, tremor is small enough not to impact daily life. We have hypothesized that a specific neural system might have evolved to reduce tremor (1), with clear survival advantages.Slow finger movements in man are characterized by steps or discontinuities that occur at approximately 10 Hz (2). These discontinuities provide a good model for studying tremor, as even though they occur within the same frequency range, they are an order of magnitude bigger (2), facilitating quantitative analysis. Work on both physiological tremor and slow finger movement discontinuities has shown that there is an approximately 10

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Section: Resultsmentioning

confidence: 99%

Spinal interneuron circuits reduce approximately 10-Hz movement discontinuities by phase cancellation

Williams

Soteropoulos

Baker

2010

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

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“…Based on current estimates, the PTN population in the hand representation of M1 is composed principally of slow PTNs (70-90% of the total population) (24,25,40). Physiological evidence indicates that slow as well as fast PTNs make monosynaptic connections with hand motoneurons (16,26,41). However, for largely technical reasons, it has not been possible to determine the overall size and importance of the monosynaptic input from slow PTNs to hand motoneurons.…”

Section: Discussionmentioning

confidence: 99%

Muscle representation in the macaque motor cortex: An anatomical perspective

Rathelot

Strick

2006

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

377

262

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“…In the preparation consisting of the brainstem, spinal cord and vestibular organs, the activity of the RS neuron was recorded from its axon in the spinal cord, whereas the brainstem and vestibular organs were rotated in different planes to determine the control system (roll, pitch, yaw) to which the neuron belongs. Afterwards, the RS neuron was stimulated and its effects on motor output of the spinal cord were detected by means of the spike-triggered averaging technique (Fetz and Cheney, 1980). The effects were found to be similar along the whole extent of the axon (Zelenin et al 2001), and they could be characterized by a combination of influences on the four motoneuron pools in any segment (Fig.…”

Section: Postural Control In Lampreymentioning

confidence: 99%

Spinal and supraspinal postural networks

Deliagina¹,

Beloozerova²,

Zelenin³

et al. 2008

Brain Research Reviews

116

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Different species maintain a particular body orientation in space (upright in humans, dorsal-side-up in quadrupeds, fish and lamprey) due to the activity of a closed-loop postural control system. We will discuss operation of spinal and supraspinal postural networks studied in a lower vertebrate (lamprey) and in two mammals (rabbit and cat).In the lamprey, the postural control system is driven by vestibular input. The key role in the postural network belongs to the reticulospinal (RS) neurons. Due to vestibular input, deviation from the stabilized body orientation in any (roll, pitch, yaw) plane leads to generation of RS commands, which are sent to the spinal cord and cause postural correction. For each of the planes, there are two groups of RS neurons responding to rotation in the opposite directions; they cause a turn opposite to the initial one. The command transmitted by an individual RS neuron causes the motor response, which contributes to the correction of posture. In each plane, the postural system stabilizes the orientation at which the antagonistic vestibular reflexes compensate for each other. Thus, in lamprey the supraspinal networks play a crucial role in stabilization of body orientation, and the function of the spinal networks is transformation of supraspinal commands into the motor pattern of postural corrections.In terrestrial quadrupeds, the postural system stabilizing the trunk orientation in the transversal plane was analyzed. It consists of two relatively independent sub-systems stabilizing orientation of the anterior and posterior parts of the trunk. They are driven by somatosensory input from limb mechanoreceptors. Each sub-system consists of two closed-loop mechanisms -spinal and spinosupraspinal. Operation of the supraspinal networks was studied by recording the posture-related activity of corticospinal neurons. The postural capacity of spinal networks was evaluated in animals with lesions to the spinal cord. Relative contribution of spinal and supraspinal mechanisms to the stabilization of trunk orientation is discussed.

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Postspike facilitation of forelimb muscle activity by primate corticomotoneuronal cells

Cited by 672 publications

References 7 publications

Spinal interneuron circuits reduce approximately 10-Hz movement discontinuities by phase cancellation

Spinal interneuron circuits reduce approximately 10-Hz movement discontinuities by phase cancellation

Muscle representation in the macaque motor cortex: An anatomical perspective

Spinal and supraspinal postural networks

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