Cortical Activity in Precision- Versus Power-Grip Tasks: An fMRI Study

• Published in: Journal of neurophysiology 2000-01, Vol.83 (1), p.528-536
• Main Authors: Ehrsson, H. Henrik, Fagergren, Anders, Jonsson, Tomas, Westling, Goran, Johansson, Roland S, Forssberg, Hans
• Format: Article
• Language: English
• Subjects: Adult; Brain Mapping; Cerebral Cortex - physiology; Fingers; Functional Laterality; Hand; Hand Strength - physiology; Humans; Isometric Contraction - physiology; Magnetic Resonance Imaging; Male; Medicin och hälsovetenskap; Motor Cortex - physiology; Parietal Lobe - physiology; Posture; Prefrontal Cortex - physiology; Thalamus - physiology
• ISSN: 0022-3077; 1522-1598
• DOI: 10.1152/jn.2000.83.1.528

  1 Motoriklab, Department of Woman and Child Health and MR Research Center, 171 76 Stockholm;   2 Division of Human Brain Research, Department of Neuroscience, Karolinska Institute, Stockholm; and   3 Department of Physiology, Umeå University, Umeå, Sweden Ehrsson, H. Henrik, Anders Fagergren, Tomas Jonsson, Göran Westling, Roland S. Johansson, and Hans Forssberg. Cortical Activity in Precision- Versus Power-Grip Tasks: An fMRI Study. J. Neurophysiol. 83: 528-536, 2000. Most manual grips can be divided in precision and power grips on the basis of phylogenetic and functional considerations. We used functional magnetic resonance imaging to compare human brain activity during force production by the right hand when subjects used a precision grip and a power grip. During the precision-grip task, subjects applied fine grip forces between the tips of the index finger and the thumb. During the power-grip task, subjects squeezed a cylindrical object using all digits in a palmar opposition grasp. The activity recorded in the primary sensory and motor cortex contralateral to the operating hand was higher when the power grip was applied than when subjects applied force with a precision grip. In contrast, the activity in the ipsilateral ventral premotor area, the rostral cingulate motor area, and at several locations in the posterior parietal and prefrontal cortices was stronger while making the precision grip than during the power grip. The power grip was associated predominately with contralateral left-sided activity, whereas the precision-grip task involved extensive activations in both hemispheres. Thus our findings indicate that in addition to the primary motor cortex, premotor and parietal areas are important for control of fingertip forces during precision grip. Moreover, the ipsilateral hemisphere appears to be strongly engaged in the control of precision-grip tasks performed with the right hand.