Article

Dissociation of brain areas associated with force production and stabilization during manipulation of unstable objects

Neuropediatric Research Unit, Department of Women's and Children's Health, Karolinska Institutet, Astrid Lindgren Children's Hospital Q2:O7, 171 76 Stockholm, Sweden.
Experimental Brain Research (Impact Factor: 2.17). 12/2011; 215(3-4):359-67. DOI: 10.1007/s00221-011-2903-9
Source: PubMed

ABSTRACT Multifinger dexterous manipulation of unstable or deformable objects requires control of both direction and magnitude of fingertip force vectors. Our aim was to study the neuroanatomical correlates of these two distinct control functions. Brain activity was measured using functional magnetic resonance imaging while 16 male subjects (age: 26-42, M = 32, SD ± 4 years) compressed four springs representing a 2 × 2 factorial design with two levels of force and instability requirements. Significant activations associated with higher instability were located bilaterally in the precentral gyri, the postcentral gyrus, and the cerebellum. In the main effect for high force, activity was found in areas located in the primary motor regions contralateral to the active hand and bilaterally in the cerebellum. An overlap in activation between the two main effects was found bilaterally in the cerebellum (lobule VI). This study not only confirms a recently described bilateral fronto-parieto-cerebellar network for manipulation of increasingly unstable objects, but critically extends our understanding by describing its differentiated modulation with both force magnitude and instability requirements. Our results, therefore, expose a previously unrecognized and context-sensitive system of brain regions that enable dexterous manipulation for different force magnitude and instability requirements of the task.

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    • "inuous measure that involves using the first digit and thumb to compress as far as possible a slender spring , prone to buckling . This requires control of fingertip motions and force vectors at very low force levels ( 2 – 3 N ) and is informative of one ' s level of neuromuscular control ( Valero - Cuevas et al . , 2003 ; Vollmer et al . , 2010 ; Holmström et al . , 2011 ; Dayanidhi and Valero - Cuevas , 2014 ; Lawrence et al . , 2014 ) . The spring is outfitted with miniature force sensors ( Measurement Specialties , Hampton , VA ) on either end to quantify the forces exerted by the fingertips . Participants were asked to compress the spring as much as possible and maintain steady state compression ( h"
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