Differential involvement of cortical and cerebellar areas using dominant and nondominant hands: An FMRI study

Abstract

Motor fMRI studies, comparing dominant (DH) and nondominant (NDH) hand activations have reported mixed findings, especially for the extent of ipsilateral (IL) activations and their relationship with task complexity. To date, no study has directly compared DH and NDH activations using an event‐related visually guided dynamic power‐grip paradigm with parametric (three) forces (GF) in healthy right‐handed subjects. We implemented a hierarchical statistical approach aimed to: (i) identify the main effect networks engaged when using either hand; (ii) characterise DH/NDH responses at different GFs; (iii) assess contralateral (CL)/IL‐specific and hemisphere‐specific activations. Beyond confirming previously reported results, this study demonstrated that increasing GF has an effect on motor response that is contextualised also by the use of DH or NDH. Linear analysis revealed increased activations in sensorimotor areas, with additional increased recruitments of subcortical and cerebellar areas when using the NDH. When looking at CL/IL‐specific activations, CL sensorimotor areas and IL cerebellum were activated with both hands. When performing the task with the NDH, several areas were also recruited including the CL cerebellum. Finally, there were hand‐side‐independent activations of nonmotor‐specific areas in the right and left hemispheres, with the right hemisphere being involved more extensively in sensori‐motor integration through associative areas while the left hemisphere showing greater activation at higher GF. This study shows that the functional networks subtending DH/NDH power‐grip visuomotor functions are qualitatively and quantitatively distinct and this should be taken into consideration when performing fMRI studies, particularly when planning interventions in patients with specific impairments. Hum Brain Mapp 36:5079–5100, 2015. © 2015 Wiley Periodicals, Inc.

Cerebellar lobules and dentate nuclei mirror cortical force‐related‐BOLD responses: Beyond all (linear) expectations

“…This contrasts with previous analyses at the whole brain level [Alahmadi et al, 2015, 2016d; Ehrsson et al, 2000; Halder et al, 2007; Keisker et al, 2009, 2010; King et al, 2014; Kuhtz‐Buschbeck et al, 2001, 2008; Neely et al, 2013; Noble et al, 2013; Spraker et al, 2012; Vaillancourt et al, 2003; Ward and Frackowiak, 2003]. Some of these studies report a linear association between GF strength and areas of the anterior cerebellum [Halder et al, 2007; Kuhtz‐Buschbeck et al, 2008] but not in the posterior cerebellum, despite the role of the posterior cerebellum in visual processing (when using visual cues) and motor planning [King et al, 2014; Stoodley and Schmahmann, 2010; Stoodley et al, 2012].…”

“…Responses in these nuclei are not frequently reported, most likely because of their small size and their T2*‐weighted signal variability, which makes their responses difficult to detect [Alahmadi et al, 2015; Diedrichsen et al, 2011; Dimitrova et al, 2006; Habas, 2010; Küper et al, 2011, 2012, 2014]. The data presented here, however, demonstrates that these nuclei show a main effect of movement as well as non‐linear force‐related‐BOLD effects.…”

“…The data presented here, however, demonstrates that these nuclei show a main effect of movement as well as non‐linear force‐related‐BOLD effects. The DN is connected to the thalamus and, from there, to motor, non‐motor, associative and cognitive cortical regions [Alahmadi et al, 2015; D'Angelo and Casali, 2013; Küper et al, 2011; Palesi et al, 2014], through the superior cerebellar peduncles. In our previous work on force‐mediated‐BOLD cortical brain activations, we observed similar non‐linear behavior in associative parietal regions [Alahmadi et al, 2016d].…”

“…Furthermore, as the deep cerebellar nuclei are also key to motor and associative processing [Dimitrova et al, 2006; Gao et al, 1996; Habas, 2010; Küper et al, 2011, 2012, 2014], and their activity is modulated by the complexity of visuomotor processes [Alahmadi et al, 2015], we expected that the DN may also respond in a non‐linear manner, according to patterns typical of associative areas of the cerebellar cortex.…”

Does Contralesional Hand Function After Neonatal Stroke Only Depend on Lesion Characteristics?

“…12 Hence, our results would further support the hypothesis of an important combined role for the mediodorsal thalamus and lobule VIIa Crus I in the control of skilled hand movement. 10,13 Finally, we show that the correlation with manual dexterity found in brain areas directly or functionally connected but anatomically remote from the infarct is mainly because of atrophy of these structures in impaired children (except for the cerebellum). Atrophy in brain regions distant from the infarct site was also shown in adults after stroke 5 and is likely related to Wallerian degeneration, deafferentation, or both.…”