Cerebellar asymmetry in a pair of monozygotic handedness‐discordant twins

Abstract

Increasing evidence for a cerebellar role in human cognition has accrued with respect to anatomically and functionally distinct lobules. Questions of laterality, however, have been largely overlooked. This study therefore introduced and applied a novel measurement protocol for comparatively bias-free analysis of cerebellar asymmetries. Volumetric measurements were performed on magnetic resonance images from a single pair of monozygotic handedness-discordant twins. Against a background of functional cortical asymmetry for verbal and visuo-spatial functional magnetic resonance imaging activation, which was mirrored in the left-handed twin (Lux et al. 2008), between-twin differences in cerebellar asymmetry are described. Interestingly, asymmetry measures for the whole cerebellum did not correspond to either the direction of hand preference or to the weaker (functional magnetic resonance imaging) lateralization of the left-handed twin. The twins both showed clockwise cerebellar torques. This mirrored a counter-clockwise cerebral torque in the right-handed twin only. Selected single cerebellar lobules V and VII displayed between-twin laterality differences that partially reflected their discrepant handedness. Whole cerebellum anatomical measures appeared to be unrelated to single functional cortical asymmetries. These analyses contribute further anatomical evidence pertaining to the existence of multiple structurally and functionally distinct cortico-cerebellar networks of the healthy human brain in vivo.

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).…”

Age-Dependent Sexually-Dimorphic Asymmetric Development of the Ferret Cerebellar Cortex

“…Such cerebro-cerebellar connections were involved in morphological lateralization of cerebral hemispheres and cerebellum, forming the torque structure. A mirror linkage of cerebral/cerebellar torques (i.e., counterclockwise versus clockwise) was revealed in right-handed humans [13]. In humans, movements of dominant hands in right-handers and visuo-spatial processing activated parietal associated cortices of the right cerebral hemisphere as well as lobules VI and VIII of the left cerebellum [6,35], corresponding to the vermal part of left CZ and PZ in our definition.…”

“…In the cerebellum, anteriorly left-biased and posterior right-biased absolute volumes of the cerebellum were reported as an intrinsic cerebellar asymmetry [13,34], indicating a clockwise cerebellar torque. A similar clockwise torque pattern was seen in the cerebellum of chimpanzees [29,30].…”

“…Furthermore, environmental variables may be involved in the asymmetric morphology of the brain. Monozygotic handedness-discordant twins exhibited the opposite direction of torque asymmetry in the cerebral hemisphere [13].…”

“…The cerebellar torque asymmetry was reportedly clockwise in primates such as humans [13] and chimpanzees [14], but counterclockwise torque asymmetry was observed in carnivores, such as ferrets [15].…”