Functional Magnetic Resonance Imaging of Motor Cortex: Hemispheric Asymmetry and Handedness

Abstract

A hemispheric asymmetry in the functional activation of the human motor cortex during contralateral (C) and ipsilateral (I) finger movements, especially in right-handed subjects, was documented with nuclear magnetic resonance imaging at high field strength (4 tesla). Whereas the right motor cortex was activated mostly during contralateral finger movements in both right-handed (C/I mean area of activation = 36.8) and left-handed (C/I = 29.9) subjects, the left motor cortex was activated substantially during ipsilateral movements in left-handed subjects (C/I = 5.4) and even more so in right-handed subjects (C/I = 1.3).

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

“…Here, it was found that secondary sensorimotor areas, such as the left premotor areas, were significantly more active at the highest GF levels than at the lowest GF. Previous studies suggest that one of the key roles of the premotor cortices is in movement planning [Grafton et al, 2002; Seong‐Gi et al, 1993; Verstynen et al, 2005]. This study supports these findings and also suggests a key modulatory role for task complexity (as opposed to execution complexity) on left hemisphere premotor cortex activity.…”

“…This is in line with the engagement (seen in our data) of the posterior parietal cortices, namely, the right SPL and the IPL, which have been shown to play a role in the integration of visual information—thus allowing online motor control through modulation of prefrontal motor areas [Hamzei et al, 2002; Marconi et al, 2001; Neely et al, 2013]. The predominance of right hemisphere regions is also supported by evidence that the right hemisphere is specifically involved in grasping networks [Begliomini et al, 2008] and by studies showing that performing sequential movements with the NDH produces greater activations in the CL hemisphere (hence here the right hemisphere) as compared to the DH [Jäncke et al, 1998; Ng et al, 2008; Seong‐Gi et al, 1993]. It has been argued that the recruitment of the motor cortex of right‐handers increases when using their NDH and that the more skilled and more widely used cortex requires less effort and, hence, less recruitment and signal [Amunts et al, 1996; Jäncke et al, 1998; Ng et al, 2008].…”

“…Compared to previous studies that claimed the prominence of the left hemisphere [Grafton et al, 2002; Marian, 1973; Seong‐Gi et al, 1993], this work interrogated the task complexity together with its execution using the DH/NDH, therefore the results are reflecting the behaviour of a shared network between the DH and NDH and not simply the linearity of the functional response with increased GF. Compared to finger tapping [Reddy et al, 2000; Cramer et al, 1999; Verstynen et al, 2005], our task required whole hand movements squeezing a ball that invokes somatosensory feedback, in addition to attending to external visual cues, i.e.…”

“…Previous studies, mostly using functional magnetic resonance imaging (fMRI), of motor network activity during motor tasks performed using the dominant (DH) and nondominant hand (NDH) have reported mixed results including: CL activations—especially localized in the primary and secondary motor cortex—produced by movement of the dominant (DH) or nondominant (NDH) hands [Verstynen et al, 2005; Ward and Frackowiak 2003]; bilateral activations using either hand [Laxmi, 1998; Seong‐Gi et al, 1993; Volkmann et al, 1998]; or strong activations ipsilateral to the hand moved [Kawashima, 1993; Seong‐Gi et al, 1993; Verstynen et al, 2005]. This heterogeneity of results is difficult to interpret, especially given methodological differences between different studies.…”

High‐angular resolution diffusion imaging tractography of cerebellar pathways from newborns to young adults

“…Cerebellar functional and morphologic asymmetry has a complex pattern which is evident in both motor and higher cognitive cerebellar activities (Hu, Shen, & Zhou, 2008; Koeneke, Lutz, Wüstenberg, & Jäncke, 2004; Matsumura et al., 2004; Rosch, Ronan, Cherkas, & Gurd, 2010; Wang et al., 2013). Cerebellar motor function is primarily, although not solely, related to movements of the ipsilateral body side (Kim et al., 1993). However, the learning of new motor skills asymmetrically activate the left cerebellar motor areas regardless of the side of the body involved in the motor movements (Matsumura et al., 2004).…”