Limits...
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.

Show MeSH

Related in: MedlinePlus

Extent of spinal cord lesion and recovery of hand dexterity. (A, a) Drawings of the C4/C5 segments showing the extent of the l-CST lesion (labelled in black) in two monkeys. (b) CaMKIIα staining of spinal sections rostral to the lesion site (C3) visualized by diaminobenzidine. A scale bar in the inset indicates 1 mm. (c) CaMKIIα staining of spinal sections caudal to the lesion site (C6). Because CaMKIIα is known to be transported in CST axons, absence of labelled axons caudal to the lesion site indicates a complete lesion of unilateral l-CST. (d1—4) CaMKIIα immunostaining of the areas indicated in Ab and Ac in the adjacent sections of Ab and Ac, visualized by Alexafluor 555. White arrows indicate the CST rostral to lesion (d1and d3) and loss of the CST caudal to lesion (d2 and d4). Scale bars indicate 1 mm. (B) Cord dorsum potentials at the C3 (top row) and C6 (second row) segments, field potentials in the DR motor nucleus at the C7 segments (third row) and conduction volleys recorded in the spinal halves at the Th12 segment (monopolar recordings, bottom row), in response to the electrical stimulation of the medullary pyramid on the contralateral side to the recording at 200 μA (pulse width 100 μs), respectively. Recordings from the lesion side (left) of the spinal cord are indicated on the left column and those from the intact side (right) of the spinal cord are indicated on the right column. (C) Recovery time course of hand dexterity in two monkeys. Performance of precision grip was plotted against the time after lesion.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2664448&req=5

Figure 2: Extent of spinal cord lesion and recovery of hand dexterity. (A, a) Drawings of the C4/C5 segments showing the extent of the l-CST lesion (labelled in black) in two monkeys. (b) CaMKIIα staining of spinal sections rostral to the lesion site (C3) visualized by diaminobenzidine. A scale bar in the inset indicates 1 mm. (c) CaMKIIα staining of spinal sections caudal to the lesion site (C6). Because CaMKIIα is known to be transported in CST axons, absence of labelled axons caudal to the lesion site indicates a complete lesion of unilateral l-CST. (d1—4) CaMKIIα immunostaining of the areas indicated in Ab and Ac in the adjacent sections of Ab and Ac, visualized by Alexafluor 555. White arrows indicate the CST rostral to lesion (d1and d3) and loss of the CST caudal to lesion (d2 and d4). Scale bars indicate 1 mm. (B) Cord dorsum potentials at the C3 (top row) and C6 (second row) segments, field potentials in the DR motor nucleus at the C7 segments (third row) and conduction volleys recorded in the spinal halves at the Th12 segment (monopolar recordings, bottom row), in response to the electrical stimulation of the medullary pyramid on the contralateral side to the recording at 200 μA (pulse width 100 μs), respectively. Recordings from the lesion side (left) of the spinal cord are indicated on the left column and those from the intact side (right) of the spinal cord are indicated on the right column. (C) Recovery time course of hand dexterity in two monkeys. Performance of precision grip was plotted against the time after lesion.

Mentions: Figure 2Aa shows the extent of the SCLs at the C4/C5 border in the two monkeys. Figure 2Ab and Ac indicates normal distribution of the l-CST in sections rostral (C3, Fig. 2Ab, d1 and d3) and caudal (C6, Fig. 2Ac) to the lesion, revealed by CaMKIIα immunohistochemistry. Lesions in both monkeys appeared to encompass the normal distribution of the l-CST (compare the blackened areas in Fig. 2Aa with the areas where labelled axons are distributed in Fig. 2Ab on both sides and only on the right side in Fig. 2Ac). CaMKIIα immunohistochemistry demonstrated robust staining of immunopositive axons rostral to lesion on both sides (C3, Fig. 2Ab, d1 and d3), whereas no CaMKIIα-positive axons caudal to lesion on the lesioned side (C6, Fig. 2Ac, d2 and d4). Thus, lesion of the l-CST was regarded as complete in both the monkeys.Figure 2


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

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

Extent of spinal cord lesion and recovery of hand dexterity. (A, a) Drawings of the C4/C5 segments showing the extent of the l-CST lesion (labelled in black) in two monkeys. (b) CaMKIIα staining of spinal sections rostral to the lesion site (C3) visualized by diaminobenzidine. A scale bar in the inset indicates 1 mm. (c) CaMKIIα staining of spinal sections caudal to the lesion site (C6). Because CaMKIIα is known to be transported in CST axons, absence of labelled axons caudal to the lesion site indicates a complete lesion of unilateral l-CST. (d1—4) CaMKIIα immunostaining of the areas indicated in Ab and Ac in the adjacent sections of Ab and Ac, visualized by Alexafluor 555. White arrows indicate the CST rostral to lesion (d1and d3) and loss of the CST caudal to lesion (d2 and d4). Scale bars indicate 1 mm. (B) Cord dorsum potentials at the C3 (top row) and C6 (second row) segments, field potentials in the DR motor nucleus at the C7 segments (third row) and conduction volleys recorded in the spinal halves at the Th12 segment (monopolar recordings, bottom row), in response to the electrical stimulation of the medullary pyramid on the contralateral side to the recording at 200 μA (pulse width 100 μs), respectively. Recordings from the lesion side (left) of the spinal cord are indicated on the left column and those from the intact side (right) of the spinal cord are indicated on the right column. (C) Recovery time course of hand dexterity in two monkeys. Performance of precision grip was plotted against the time after lesion.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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

Figure 2: Extent of spinal cord lesion and recovery of hand dexterity. (A, a) Drawings of the C4/C5 segments showing the extent of the l-CST lesion (labelled in black) in two monkeys. (b) CaMKIIα staining of spinal sections rostral to the lesion site (C3) visualized by diaminobenzidine. A scale bar in the inset indicates 1 mm. (c) CaMKIIα staining of spinal sections caudal to the lesion site (C6). Because CaMKIIα is known to be transported in CST axons, absence of labelled axons caudal to the lesion site indicates a complete lesion of unilateral l-CST. (d1—4) CaMKIIα immunostaining of the areas indicated in Ab and Ac in the adjacent sections of Ab and Ac, visualized by Alexafluor 555. White arrows indicate the CST rostral to lesion (d1and d3) and loss of the CST caudal to lesion (d2 and d4). Scale bars indicate 1 mm. (B) Cord dorsum potentials at the C3 (top row) and C6 (second row) segments, field potentials in the DR motor nucleus at the C7 segments (third row) and conduction volleys recorded in the spinal halves at the Th12 segment (monopolar recordings, bottom row), in response to the electrical stimulation of the medullary pyramid on the contralateral side to the recording at 200 μA (pulse width 100 μs), respectively. Recordings from the lesion side (left) of the spinal cord are indicated on the left column and those from the intact side (right) of the spinal cord are indicated on the right column. (C) Recovery time course of hand dexterity in two monkeys. Performance of precision grip was plotted against the time after lesion.
Mentions: Figure 2Aa shows the extent of the SCLs at the C4/C5 border in the two monkeys. Figure 2Ab and Ac indicates normal distribution of the l-CST in sections rostral (C3, Fig. 2Ab, d1 and d3) and caudal (C6, Fig. 2Ac) to the lesion, revealed by CaMKIIα immunohistochemistry. Lesions in both monkeys appeared to encompass the normal distribution of the l-CST (compare the blackened areas in Fig. 2Aa with the areas where labelled axons are distributed in Fig. 2Ab on both sides and only on the right side in Fig. 2Ac). CaMKIIα immunohistochemistry demonstrated robust staining of immunopositive axons rostral to lesion on both sides (C3, Fig. 2Ab, d1 and d3), whereas no CaMKIIα-positive axons caudal to lesion on the lesioned side (C6, Fig. 2Ac, d2 and d4). Thus, lesion of the l-CST was regarded as complete in both the monkeys.Figure 2

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