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Extracting extensor digitorum communis activation patterns using high-density surface electromyography.

Hu X, Suresh NL, Xue C, Rymer WZ - Front Physiol (2015)

Bottom Line: Our results revealed distinct activation patterns during individual finger extensions, especially between index and middle finger extensions, although the activation between ring and little finger extensions showed strong covariance.We also found that distinct activation patterns were more discernible in the proximal-distal direction than in the radial-ulnar direction.Such information can also provide a basis for understanding hand impairment in individuals with neural disorders.

View Article: PubMed Central - PubMed

Affiliation: Sensory Motor Performance Program, Single Motor Unit Lab, Rehabilitation Institute of Chicago Chicago, IL, USA.

ABSTRACT
The extensor digitorum communis muscle plays an important role in hand dexterity during object manipulations. This multi-tendinous muscle is believed to be controlled through separate motoneuron pools, thereby forming different compartments that control individual digits. However, due to the complex anatomical variations across individuals and the flexibility of neural control strategies, the spatial activation patterns of the extensor digitorum communis compartments during individual finger extension have not been fully tracked under different task conditions. The objective of this study was to quantify the global spatial activation patterns of the extensor digitorum communis using high-density (7 × 9) surface electromyogram (EMG) recordings. The muscle activation map (based on the root mean square of the EMG) was constructed when subjects performed individual four finger extensions at the metacarpophalangeal joint, at different effort levels and under different finger constraints (static and dynamic). Our results revealed distinct activation patterns during individual finger extensions, especially between index and middle finger extensions, although the activation between ring and little finger extensions showed strong covariance. The activation map was relatively consistent at different muscle contraction levels and for different finger constraint conditions. We also found that distinct activation patterns were more discernible in the proximal-distal direction than in the radial-ulnar direction. The global spatial activation map utilizing surface grid EMG of the extensor digitorum communis muscle provides information for localizing individual compartments of the extensor muscle during finger extensions. This is of potential value for identifying more selective control input for assistive devices. Such information can also provide a basis for understanding hand impairment in individuals with neural disorders.

No MeSH data available.


Related in: MedlinePlus

Sum of squared difference (SSD) between normalized RMS maps of different tasks. RMS maps were normalized with respect to their own maximum values. (A) SSD between four-finger extension and individual finger extensions in different conditions. Error bars represent standard errors between subjects. (B) SSD between dynamic and static extensions in high and low conditions. (C) SSD between high and low extensions in dynamic and static conditions.
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Figure 5: Sum of squared difference (SSD) between normalized RMS maps of different tasks. RMS maps were normalized with respect to their own maximum values. (A) SSD between four-finger extension and individual finger extensions in different conditions. Error bars represent standard errors between subjects. (B) SSD between dynamic and static extensions in high and low conditions. (C) SSD between high and low extensions in dynamic and static conditions.

Mentions: Given the inhomogeneity of the extensor digitorum communis activation, the centroid may not be sensitive enough to identify specific shift of activation distribution shapes. To better quantify the difference of activation, we calculated the sum of squared difference (SSD) in the normalized RMS between the different task conditions (Figure 5). When the SSD between the four-finger extension and individual finger extension was calculated to estimate the difference in extensor digitorum communis spatial activation patterns between single finger and all four-finger extensions (Figure 5A), ~22–36% of difference was found in index finger extension, and ~40% of difference was found in middle finger extension. In contrast, only about 12–23% of difference was found in ring and little finger extensions. The ANOVA revealed a significant finger × constraint interaction [F(3, 27) = 9.20, p = 0.001], and the SSD was not influenced by effort level [F(1, 9) = 1.11, p = 0.32]. In index and little finger extension tasks, the SSD was significantly larger in the dynamic than the static contractions (p < 0.05).


Extracting extensor digitorum communis activation patterns using high-density surface electromyography.

Hu X, Suresh NL, Xue C, Rymer WZ - Front Physiol (2015)

Sum of squared difference (SSD) between normalized RMS maps of different tasks. RMS maps were normalized with respect to their own maximum values. (A) SSD between four-finger extension and individual finger extensions in different conditions. Error bars represent standard errors between subjects. (B) SSD between dynamic and static extensions in high and low conditions. (C) SSD between high and low extensions in dynamic and static conditions.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4593961&req=5

Figure 5: Sum of squared difference (SSD) between normalized RMS maps of different tasks. RMS maps were normalized with respect to their own maximum values. (A) SSD between four-finger extension and individual finger extensions in different conditions. Error bars represent standard errors between subjects. (B) SSD between dynamic and static extensions in high and low conditions. (C) SSD between high and low extensions in dynamic and static conditions.
Mentions: Given the inhomogeneity of the extensor digitorum communis activation, the centroid may not be sensitive enough to identify specific shift of activation distribution shapes. To better quantify the difference of activation, we calculated the sum of squared difference (SSD) in the normalized RMS between the different task conditions (Figure 5). When the SSD between the four-finger extension and individual finger extension was calculated to estimate the difference in extensor digitorum communis spatial activation patterns between single finger and all four-finger extensions (Figure 5A), ~22–36% of difference was found in index finger extension, and ~40% of difference was found in middle finger extension. In contrast, only about 12–23% of difference was found in ring and little finger extensions. The ANOVA revealed a significant finger × constraint interaction [F(3, 27) = 9.20, p = 0.001], and the SSD was not influenced by effort level [F(1, 9) = 1.11, p = 0.32]. In index and little finger extension tasks, the SSD was significantly larger in the dynamic than the static contractions (p < 0.05).

Bottom Line: Our results revealed distinct activation patterns during individual finger extensions, especially between index and middle finger extensions, although the activation between ring and little finger extensions showed strong covariance.We also found that distinct activation patterns were more discernible in the proximal-distal direction than in the radial-ulnar direction.Such information can also provide a basis for understanding hand impairment in individuals with neural disorders.

View Article: PubMed Central - PubMed

Affiliation: Sensory Motor Performance Program, Single Motor Unit Lab, Rehabilitation Institute of Chicago Chicago, IL, USA.

ABSTRACT
The extensor digitorum communis muscle plays an important role in hand dexterity during object manipulations. This multi-tendinous muscle is believed to be controlled through separate motoneuron pools, thereby forming different compartments that control individual digits. However, due to the complex anatomical variations across individuals and the flexibility of neural control strategies, the spatial activation patterns of the extensor digitorum communis compartments during individual finger extension have not been fully tracked under different task conditions. The objective of this study was to quantify the global spatial activation patterns of the extensor digitorum communis using high-density (7 × 9) surface electromyogram (EMG) recordings. The muscle activation map (based on the root mean square of the EMG) was constructed when subjects performed individual four finger extensions at the metacarpophalangeal joint, at different effort levels and under different finger constraints (static and dynamic). Our results revealed distinct activation patterns during individual finger extensions, especially between index and middle finger extensions, although the activation between ring and little finger extensions showed strong covariance. The activation map was relatively consistent at different muscle contraction levels and for different finger constraint conditions. We also found that distinct activation patterns were more discernible in the proximal-distal direction than in the radial-ulnar direction. The global spatial activation map utilizing surface grid EMG of the extensor digitorum communis muscle provides information for localizing individual compartments of the extensor muscle during finger extensions. This is of potential value for identifying more selective control input for assistive devices. Such information can also provide a basis for understanding hand impairment in individuals with neural disorders.

No MeSH data available.


Related in: MedlinePlus