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Two distinct ipsilateral cortical representations for individuated finger movements.

Diedrichsen J, Wiestler T, Krakauer JW - Cereb. Cortex (2012)

Bottom Line: A second type of representation becomes evident in caudal premotor and anterior parietal cortices during bimanual actions.In these regions, ipsilateral actions are represented as nonlinear modulation of activity patterns related to contralateral actions, an encoding scheme that may provide the neural substrate for coordinating bimanual movements.We conclude that ipsilateral cortical representations change their informational content and functional role, depending on the behavioral context.

View Article: PubMed Central - PubMed

Affiliation: Institute of Cognitive Neuroscience, University College London, London, UK. j.diedrichsen@ucl.ac.uk

ABSTRACT
Movements of the upper limb are controlled mostly through the contralateral hemisphere. Although overall activity changes in the ipsilateral motor cortex have been reported, their functional significance remains unclear. Using human functional imaging, we analyzed neural finger representations by studying differences in fine-grained activation patterns for single isometric finger presses. We demonstrate that cortical motor areas encode ipsilateral movements in 2 fundamentally different ways. During unimanual ipsilateral finger presses, primary sensory and motor cortices show, underneath global suppression, finger-specific activity patterns that are nearly identical to those elicited by contralateral mirror-symmetric action. This component vanishes when both motor cortices are functionally engaged during bimanual actions. We suggest that the ipsilateral representation present during unimanual presses arises because otherwise functionally idle circuits are driven by input from the opposite hemisphere. A second type of representation becomes evident in caudal premotor and anterior parietal cortices during bimanual actions. In these regions, ipsilateral actions are represented as nonlinear modulation of activity patterns related to contralateral actions, an encoding scheme that may provide the neural substrate for coordinating bimanual movements. We conclude that ipsilateral cortical representations change their informational content and functional role, depending on the behavioral context.

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Related in: MedlinePlus

Representations of ipsilateral fingers during unimanual and bimanual actions. (A) Surface maps of the classification accuracy for the ipsilateral finger (40% accuracy threshold, Z = 1) during unimanual (upper row) and bimanual (lower row) finger presses. (B) Predicted accuracies, assuming that contra- and ipsilateral patterns superimpose linearly. (C) Observed classification accuracy in informative subregions (see Materials and Methods) of 3 anatomical ROIs for contralateral (red) and ipsilateral (blue) fingers. Results are averaged across the 2 hemispheres. Error bars represent across-subject standard error of the mean. (D) Spatial relationship of areas encoding the contralateral (50% threshold, red) and ipsilateral fingers (40% threshold, blue) during bimanual actions. Circles indicate the individual COGs of the functional finger ROI of the precentral and postcentral gyri. CS, central sulcus; SFS, superior frontal sulcus.
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BHS120F5: Representations of ipsilateral fingers during unimanual and bimanual actions. (A) Surface maps of the classification accuracy for the ipsilateral finger (40% accuracy threshold, Z = 1) during unimanual (upper row) and bimanual (lower row) finger presses. (B) Predicted accuracies, assuming that contra- and ipsilateral patterns superimpose linearly. (C) Observed classification accuracy in informative subregions (see Materials and Methods) of 3 anatomical ROIs for contralateral (red) and ipsilateral (blue) fingers. Results are averaged across the 2 hemispheres. Error bars represent across-subject standard error of the mean. (D) Spatial relationship of areas encoding the contralateral (50% threshold, red) and ipsilateral fingers (40% threshold, blue) during bimanual actions. Circles indicate the individual COGs of the functional finger ROI of the precentral and postcentral gyri. CS, central sulcus; SFS, superior frontal sulcus.

Mentions: For the unimanual condition (Fig. 5A, upper row), we replicated Experiment 1: large areas of the sensory motor cortex encoded the ipsilateral action (Table 3, unimanual). Again, these regions were nearly identical to those encoding the contralateral finger presses (data not shown).Table 3


Two distinct ipsilateral cortical representations for individuated finger movements.

Diedrichsen J, Wiestler T, Krakauer JW - Cereb. Cortex (2012)

Representations of ipsilateral fingers during unimanual and bimanual actions. (A) Surface maps of the classification accuracy for the ipsilateral finger (40% accuracy threshold, Z = 1) during unimanual (upper row) and bimanual (lower row) finger presses. (B) Predicted accuracies, assuming that contra- and ipsilateral patterns superimpose linearly. (C) Observed classification accuracy in informative subregions (see Materials and Methods) of 3 anatomical ROIs for contralateral (red) and ipsilateral (blue) fingers. Results are averaged across the 2 hemispheres. Error bars represent across-subject standard error of the mean. (D) Spatial relationship of areas encoding the contralateral (50% threshold, red) and ipsilateral fingers (40% threshold, blue) during bimanual actions. Circles indicate the individual COGs of the functional finger ROI of the precentral and postcentral gyri. CS, central sulcus; SFS, superior frontal sulcus.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3643717&req=5

BHS120F5: Representations of ipsilateral fingers during unimanual and bimanual actions. (A) Surface maps of the classification accuracy for the ipsilateral finger (40% accuracy threshold, Z = 1) during unimanual (upper row) and bimanual (lower row) finger presses. (B) Predicted accuracies, assuming that contra- and ipsilateral patterns superimpose linearly. (C) Observed classification accuracy in informative subregions (see Materials and Methods) of 3 anatomical ROIs for contralateral (red) and ipsilateral (blue) fingers. Results are averaged across the 2 hemispheres. Error bars represent across-subject standard error of the mean. (D) Spatial relationship of areas encoding the contralateral (50% threshold, red) and ipsilateral fingers (40% threshold, blue) during bimanual actions. Circles indicate the individual COGs of the functional finger ROI of the precentral and postcentral gyri. CS, central sulcus; SFS, superior frontal sulcus.
Mentions: For the unimanual condition (Fig. 5A, upper row), we replicated Experiment 1: large areas of the sensory motor cortex encoded the ipsilateral action (Table 3, unimanual). Again, these regions were nearly identical to those encoding the contralateral finger presses (data not shown).Table 3

Bottom Line: A second type of representation becomes evident in caudal premotor and anterior parietal cortices during bimanual actions.In these regions, ipsilateral actions are represented as nonlinear modulation of activity patterns related to contralateral actions, an encoding scheme that may provide the neural substrate for coordinating bimanual movements.We conclude that ipsilateral cortical representations change their informational content and functional role, depending on the behavioral context.

View Article: PubMed Central - PubMed

Affiliation: Institute of Cognitive Neuroscience, University College London, London, UK. j.diedrichsen@ucl.ac.uk

ABSTRACT
Movements of the upper limb are controlled mostly through the contralateral hemisphere. Although overall activity changes in the ipsilateral motor cortex have been reported, their functional significance remains unclear. Using human functional imaging, we analyzed neural finger representations by studying differences in fine-grained activation patterns for single isometric finger presses. We demonstrate that cortical motor areas encode ipsilateral movements in 2 fundamentally different ways. During unimanual ipsilateral finger presses, primary sensory and motor cortices show, underneath global suppression, finger-specific activity patterns that are nearly identical to those elicited by contralateral mirror-symmetric action. This component vanishes when both motor cortices are functionally engaged during bimanual actions. We suggest that the ipsilateral representation present during unimanual presses arises because otherwise functionally idle circuits are driven by input from the opposite hemisphere. A second type of representation becomes evident in caudal premotor and anterior parietal cortices during bimanual actions. In these regions, ipsilateral actions are represented as nonlinear modulation of activity patterns related to contralateral actions, an encoding scheme that may provide the neural substrate for coordinating bimanual movements. We conclude that ipsilateral cortical representations change their informational content and functional role, depending on the behavioral context.

Show MeSH
Related in: MedlinePlus