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Neural correlates of skilled movement : functional mapping of the human brain with fMRI and PET

thesis
posted on 2024-09-02, 15:26 authored by H Henrik Ehrsson

Humans have unique abilities to perform certain types of skilled voluntary movements. In this thesis we examine the neural substrates of. (i) fine digit actions, in particular the control of fingertip forces during manipulation, and (ii) the coordination of voluntary movements of different limbs. In addition, (iii) we investigate the neural correlates of the kinesthetic perception and imagery of limb movement. Functional magnetic resonance imaging and positron emission tomography were used to measure the blood oxygenation level dependent contrast and regional cerebral blood flow as indexes of neuronal activity.

(i) We investigated the active cortical areas associated with the control of fingertip forces and production of hand postures with independent movements of the digits. In the fingertip force experiments the subjects used the right index finger and thumb to apply forces to a fixed object. These precision grip tasks consistently activated a set of bilateral fronto-parietal areas including the primary motor cortex (MI), the nonprimary motor areas and the posterior parietal cortex (PPC). It was found that the control of small grip forces during precision grips is more dependent on non-primary Eronto-parietal areas than when the force is excessively large or when a power grip is used between all digits and the palm. Specifically, we show that the bilateral ventral premotor cortex, area 44, supramarginal cortex and the right intraparietal cortex (IPS) are involved in the control of small precision grip forces. Furthermore, areas in the left PPC are involved in the control of lift forces for object displacement whereas the right posterior IPS might support the coordination of grip-lift forces during precision grips. Further, we show that M1 is particularly active during forceful gripping, but also so when holding an object close to the slip point requiring very precise force control. The SMA, CMA and left supramarginal cortex are also active in this latter task. We also demonstrate that the control of independent movements of the digits during the production of hand postures involves the SMA, the bilateral dorsal premotor cortex, postcentral cortex, cerebellum, and the left anterior IPS. In. summary, we conclude that fine digit actions in humans depend on a network of bilateral fronto-parietal areas that are active in a task-dependent manner.

(ii) The brain regions controlling coordinated movements of limbs were examined. A main conclusion is that coordinated movements of two limbs are controlled by the areas that control isolated movements of the same limbs. In addition, we show that two natural pattems of bimanual temporal coordination are supported by distinct regions: the left anterior cerebellar lobe (and caudal CMA and precuneus) is associated with synchronous finger tapping, whilst alternating finger tapping strongly engages bilateral fronto-parieto-temporal areas. Furthermore, the media] cerebellum is strongly activated in polyrhythmic tasks. These results are discussed in relation to the hypothesis that different brain regions support temporal and spatial inter-limb coordination.

(iii) The neural correlates of the kinesthetic perception and imagery of limb movement were examined. We show that when subjects experience an illusory limb movement elicited by vibration stimuli (~80 Hz) applied to the skin over the tendon of a muscle, the contralateral M1, S1, SMA, and CMA are active. Likewise, when subjects imagine that they are executing movements of their fingers, toes and tongue, some of the coffesponding gross somatotopical zones of the frontal motor areas are recruited. Thus the frontal motor areas are involved in the kinesthetic perception and imagery of limb movement, in addition to the execution of action.

List of scientific papers

I. Ehrsson HH, Fagergren A, Jonsson T, Westling G, Johansson RS, Forssberg H (2000). "Cortical activity in precision- versus power-grip tasks: an fMRI st" J Neurophysiol 83(1): 528-36
https://pubmed.ncbi.nlm.nih.gov/10634893

II. Ehrsson HH, Fagergren E, Forssberg H (2001). "Differential fronto-parietal activation depending on force used in a precision grip task: an fMRI study. " J Neurophysiol 85(6): 2613-23
https://pubmed.ncbi.nlm.nih.gov/11387405

III. Ehrsson HH, Fagergren A, Johansson RS, Forssberg H (2001). "Cortical activation when humans apply grip force, lift force, and coordinated grip-lift forces in a precsion grip task." (Submitted)

IV. Kuhtz-Buschbeck JP, Ehrsson HH, Forssberg H (2001). "Human brain activity in the control of fine static precsion grip forces; an fMRI study," Eur J Neurosci (In Print)

V. Ehrsson HH, Kuhtz-Buschbeck JP, Forssberg H (2001). "Brain activation during the production of hand postures: independent versus synergistic movements of the digits." (Submitted)

VI. Ehrsson HH, Naito E, Geyer S, Amunts K, Zilles K, Forssberg H, Roland PE (2000). "Simultaneous movements of upper and lower limbs are coordinated by motor representations that are shared by both limbs: a PET study" Eur J Neurosci 12(9): 3385-98
https://pubmed.ncbi.nlm.nih.gov/10998121

VII. Ullen F, Forssberg H, Ehrsson HH (2001). "Neural networks for the coordination of the hands in time." (Submitted)

VIII. Naito E, Ehrsson HH, Geyer S, Zilles K, Roland PE (1999). "Illusory arm movements activate cortical motor areas: a positron emission tomography study. " J Neurosci 19(14): 6134-44
https://pubmed.ncbi.nlm.nih.gov/10407049

IX. Naito E, Ehrsson HH (2001). "Kinesthetic illusion of wrist movement activate motor areas." (Submitted)

X. Ehrsson HH, Naito E (2001). "Mental imagery of voluntary movement of finger, toes, and tongue activates corresponding body-part specific motor representations." (Manuscript)

History

Defence date

2001-09-14

Department

  • Department of Women's and Children's Health

Publication year

2001

Thesis type

  • Doctoral thesis

ISBN-10

91-628-4938-7

Number of supporting papers

10

Language

  • eng

Original publication date

2001-08-24

Author name in thesis

Ehrsson, H Henrik

Original department name

Department of Women's and Children's Health

Place of publication

Stockholm

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