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A subcortical oscillatory network contributes to recovery of hand dexterity after spinal cord injury.

Nishimura Y, Morichika Y, Isa T - Brain (2009)

Bottom Line: Activities of antagonist muscle pairs showed co-activation and oscillated coherently at frequencies of 30-46 Hz (gamma-band) by 1-month post-lesion.Such gamma-band inter-muscular coupling was not observed pre-lesion, but emerged and was strengthened and distributed over a wide range of hand/arm muscles along with the recovery.Neither the beta-band (14-30 Hz) cortico-muscular coupling observed pre-lesion nor a gamma-band oscillation was observed in the motor cortex post-lesion.

View Article: PubMed Central - PubMed

Affiliation: Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Japan. yukio@u.washington.edu

ABSTRACT
Recent studies have shown that after partial spinal-cord lesion at the mid-cervical segment, the remaining pathways compensate for restoring finger dexterity; however, how they control hand/arm muscles has remained unclear. To elucidate the changes in dynamic properties of neural circuits connecting the motor cortex and hand/arm muscles, we investigated the cortico- and inter-muscular couplings of activities throughout the recovery period after the spinal-cord lesion. Activities of antagonist muscle pairs showed co-activation and oscillated coherently at frequencies of 30-46 Hz (gamma-band) by 1-month post-lesion. Such gamma-band inter-muscular coupling was not observed pre-lesion, but emerged and was strengthened and distributed over a wide range of hand/arm muscles along with the recovery. Neither the beta-band (14-30 Hz) cortico-muscular coupling observed pre-lesion nor a gamma-band oscillation was observed in the motor cortex post-lesion. We propose that a subcortical oscillator commonly recruits hand/arm muscles, via remaining pathways such as reticulospinal and/or propriospinal tracts, independent of cortical oscillation, and contributes to functional recovery.

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Related in: MedlinePlus

An example of unprocessed recordings of local field potentials (LFPs) from hand territory of primary motor cortex in both hemispheres and rectified EMGs in a variety of forearm muscles in ipsilesional side, together with the force applied to the levers by the index finger and thumb during the force-tracking precision grip task. Note that oscillatory activity in the LFP appears in both hemispheres during the hold phase. Data were obtained in Monkey Mu before lesion. coM1 = primary motor cortex in the contralesional hemisphere; ipM1 = primary motor cortex in the ipsilesional hemisphere.
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Figure 1: An example of unprocessed recordings of local field potentials (LFPs) from hand territory of primary motor cortex in both hemispheres and rectified EMGs in a variety of forearm muscles in ipsilesional side, together with the force applied to the levers by the index finger and thumb during the force-tracking precision grip task. Note that oscillatory activity in the LFP appears in both hemispheres during the hold phase. Data were obtained in Monkey Mu before lesion. coM1 = primary motor cortex in the contralesional hemisphere; ipM1 = primary motor cortex in the ipsilesional hemisphere.

Mentions: Monkeys were trained to perform the force-tracking precision grip task (Fig. 1) for juice reward with the left hand, which is ipsilateral side to the lesion. The task required two independent levers to be pinched between the index finger and the thumb and held within their respective, electronically defined isometric force windows. Both levers had to be held correctly for 3.5 s, after which a tone signalled that the levers could be released for the animals to obtain a reward. Monkeys were over-trained in this task for longer than 6 months before lesion.Figure 1


A subcortical oscillatory network contributes to recovery of hand dexterity after spinal cord injury.

Nishimura Y, Morichika Y, Isa T - Brain (2009)

An example of unprocessed recordings of local field potentials (LFPs) from hand territory of primary motor cortex in both hemispheres and rectified EMGs in a variety of forearm muscles in ipsilesional side, together with the force applied to the levers by the index finger and thumb during the force-tracking precision grip task. Note that oscillatory activity in the LFP appears in both hemispheres during the hold phase. Data were obtained in Monkey Mu before lesion. coM1 = primary motor cortex in the contralesional hemisphere; ipM1 = primary motor cortex in the ipsilesional hemisphere.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2664448&req=5

Figure 1: An example of unprocessed recordings of local field potentials (LFPs) from hand territory of primary motor cortex in both hemispheres and rectified EMGs in a variety of forearm muscles in ipsilesional side, together with the force applied to the levers by the index finger and thumb during the force-tracking precision grip task. Note that oscillatory activity in the LFP appears in both hemispheres during the hold phase. Data were obtained in Monkey Mu before lesion. coM1 = primary motor cortex in the contralesional hemisphere; ipM1 = primary motor cortex in the ipsilesional hemisphere.
Mentions: Monkeys were trained to perform the force-tracking precision grip task (Fig. 1) for juice reward with the left hand, which is ipsilateral side to the lesion. The task required two independent levers to be pinched between the index finger and the thumb and held within their respective, electronically defined isometric force windows. Both levers had to be held correctly for 3.5 s, after which a tone signalled that the levers could be released for the animals to obtain a reward. Monkeys were over-trained in this task for longer than 6 months before lesion.Figure 1

Bottom Line: Activities of antagonist muscle pairs showed co-activation and oscillated coherently at frequencies of 30-46 Hz (gamma-band) by 1-month post-lesion.Such gamma-band inter-muscular coupling was not observed pre-lesion, but emerged and was strengthened and distributed over a wide range of hand/arm muscles along with the recovery.Neither the beta-band (14-30 Hz) cortico-muscular coupling observed pre-lesion nor a gamma-band oscillation was observed in the motor cortex post-lesion.

View Article: PubMed Central - PubMed

Affiliation: Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Japan. yukio@u.washington.edu

ABSTRACT
Recent studies have shown that after partial spinal-cord lesion at the mid-cervical segment, the remaining pathways compensate for restoring finger dexterity; however, how they control hand/arm muscles has remained unclear. To elucidate the changes in dynamic properties of neural circuits connecting the motor cortex and hand/arm muscles, we investigated the cortico- and inter-muscular couplings of activities throughout the recovery period after the spinal-cord lesion. Activities of antagonist muscle pairs showed co-activation and oscillated coherently at frequencies of 30-46 Hz (gamma-band) by 1-month post-lesion. Such gamma-band inter-muscular coupling was not observed pre-lesion, but emerged and was strengthened and distributed over a wide range of hand/arm muscles along with the recovery. Neither the beta-band (14-30 Hz) cortico-muscular coupling observed pre-lesion nor a gamma-band oscillation was observed in the motor cortex post-lesion. We propose that a subcortical oscillator commonly recruits hand/arm muscles, via remaining pathways such as reticulospinal and/or propriospinal tracts, independent of cortical oscillation, and contributes to functional recovery.

Show MeSH
Related in: MedlinePlus