Abstract
Recording of neural activity during grasping actions in macaques showed that grasp-related sensorimotor transformations are accomplished in a circuit constituted by the anterior part of the intraparietal sulcus (AIP), the ventral (F5) and the dorsal (F2) region of the premotor area. In humans, neuroimaging studies have revealed the existence of a similar circuit, involving the putative homolog of macaque areas AIP, F5, and F2. These studies have mainly considered grasping movements performed with the right dominant hand and only a few studies have measured brain activity associated with a movement performed with the left non-dominant hand. As a consequence of this gap, how the brain controls for grasping movement performed with the dominant and the non-dominant hand still represents an open question. A functional magnetic resonance imaging (fMRI) experiment has been conducted, and effective connectivity (dynamic causal modeling, DCM) was used to assess how connectivity among grasping-related areas is modulated by hand (i.e., left and right) during the execution of grasping movements toward a small object requiring precision grasping. Results underlined boosted inter-hemispheric couplings between dorsal premotor cortices during the execution of movements performed with the left rather than the right dominant hand. More specifically, they suggest that the dorsal premotor cortices may play a fundamental role in monitoring the configuration of fingers when grasping movements are performed by either the right and the left hand. This role becomes particularly evident when the hand less-skilled (i.e., the left hand) to perform such action is utilized. The results are discussed in light of recent theories put forward to explain how parieto-frontal connectivity is modulated by the execution of prehensile movements.
Highlights
Human motor system organization is based on the principle of contralateral control of distal movement components, which is reflected at an anatomical level in a nearly complete cross-over of corticospinal fibers innervating distal muscles
Functional magnetic resonance imaging, electroencephalography (EEG), positron emission tomography (PET), magnetoencephalography (MEG), and transcranial magnetic stimulation (TMS) experiments have been recently utilized to study whether behavioral asymmetry is associated with asymmetric neural tissue activation in the two hemispheres (Kim et al, 1993; Baraldi et al, 1999; Brouwer et al, 2001; Kobayashi et al, 2003; Pollok et al, 2006; Basso et al, 2006; Begliomini et al, 2008; Martin et al, 2011; Kourtis et al, 2014)
We hypothesized that, according to the model suggested by Rizzolatti and Luppino (2001), emphasizing the role of the connection anterior part of the intraparietal sulcus (AIP)-ventral premotor cortex (vPMC) in visuo-motor transformation underlying grasping movements, the connections between vPMCs could be‘affected’ by precision grip movements performed with the left nondominant hand (LNH)
Summary
Human motor system organization is based on the principle of contralateral control of distal movement components, which is reflected at an anatomical level in a nearly complete cross-over of corticospinal fibers innervating distal muscles. Recent neuroimaging techniques have made it possible to investigate the relationship between hand dominance and functional brain architecture In this respect, functional magnetic resonance imaging (fMRI), electroencephalography (EEG), positron emission tomography (PET), magnetoencephalography (MEG), and transcranial magnetic stimulation (TMS) experiments have been recently utilized to study whether behavioral asymmetry (hand dominance) is associated with asymmetric neural tissue activation in the two hemispheres (Kim et al, 1993; Baraldi et al, 1999; Brouwer et al, 2001; Kobayashi et al, 2003; Pollok et al, 2006; Basso et al, 2006; Begliomini et al, 2008; Martin et al, 2011; Kourtis et al, 2014). Those studies have produced differing results in particular with regard to the activation of ipsilateral motor cortical areas in connection to the moving hand; the majority of fMRI studies has confirmed contralateral and ipsilateral activation within motor-related areas (Kim et al, 1993; Baraldi et al, 1999; Kobayashi et al, 2003; Verstynen et al, 2005)
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