Grip-dependent excitability of the motor system for intrinsic and extrinsic hand muscles during grasping imagination and grasping action
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1
University of Verona, Italy
The brain may accurately predict the type of digits and the forces needed to efficiently manipulate objects in relation to their mechanical properties such as size, weight and weight distribution (density). These predictions may involve different processes: a central representation based on sensorimotor memory, a direct visual analysis about object dimensions along with the selection of the type of grip that is specific for the task at hand (precision or power). In order to successfully perform the action, each one of these processes needs to consider an appropriate muscle modulation based on the object’s dimensions. We show that when imagining grasping spheres made of different densities (aluminum and balsa wood), diameters (1 and 10 cm) and weights (from 0.2 to 2700g), the motor system scaled the object’s dimensions by modulating the muscles that would be used for a precision and power grip as if the action would be really performed. We found that the FDI muscle (First Digital Interosseous) was more active than the ADM (Abductor Digiti Minimi) and the FDS (Flexor Digitorum Superficialis) for the small spheres, while the opposite happened for the bigger spheres by showing muscle selectivity for the grip required. The same pattern was observed when subjects were asked to perform the action. Moreover, during the imagination the extrinsic hand muscle (FDS) was more active for the sphere made of aluminum than the one made on balsa, while during the actual action all three muscles discriminated density. For weight dimension both during action and imagination, the ADM and FDS, but not the FDI, scaled according to weight increases. We suggest that the predominant process applied for grasp planning is mainly due to selecting the muscle and the relative muscle modulation in order to “in-form” the grip required for the task at hand.
Conference:
41st European Brain and Behaviour Society Meeting, Rhodes Island, Greece, 13 Sep - 18 Sep, 2009.
Presentation Type:
Poster Presentation
Topic:
Poster presentations
Citation:
Cesari
P,
Fiorio
M and
Pizzolato
F
(2009). Grip-dependent excitability of the motor system for intrinsic and extrinsic hand muscles during grasping imagination and grasping action.
Conference Abstract:
41st European Brain and Behaviour Society Meeting.
doi: 10.3389/conf.neuro.08.2009.09.108
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Received:
08 Jun 2009;
Published Online:
08 Jun 2009.
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Correspondence:
Paola Cesari, University of Verona, Verona, Italy, paola.cesari@univr.it