Neurobiology of perceptual and motor timing in children with spina bifida in relation to cerebellar volume

Abstract

The cerebellum is important for perceptual and motor timing in the mature brain, but the timing function of the cerebellum in the immature brain is less well understood. We investigated timing in children with spina bifida meningomyelocele (SB), a neural tube defect that involves cerebellar dysgenesis, and in age-matched controls. Specifically, we studied perceptual timing (judgements of 400 ms duration) and motor timing (isochronous motor tapping); measured cerebellar volumes; and related perceptual and motor timing to each other and to cerebellar volume measurements. Children with SB had impairments in the perception of duration (around 400 ms) but not frequency (around 3000 Hz), showing that their perceptual timing deficit was not a generalized auditory impairment. Children with SB had motor timing deficits on unpaced but not paced isochronous tapping, and their unpaced timing performance was associated with clock variance rather than with motor implementation. Perceptual and motor timing were correlated, suggesting that children with SB have impairments in a central timing mechanism. Children with SB, especially those with upper spinal cord lesions, had significant cerebellar volume reductions in grey and white matter, as well as different regional patterns of grey matter, white matter and CSF. Duration perception was correlated with cerebellar volumes, and the number of valid tapping trials was correlated with cerebellar volumes in the SB group, which data demonstrate structure-function relations between timing and cerebellar volumes.

Evidence of Cerebellar Dysfunction in Children with Myelomeningocele?

“…The number of valid tapping trials was positively correlated with anterior and inferior-posterior cerebellar volumes in the children with SBM. Even though perceptual and motor timing are different and controlled by separate structures, these two components are related to each other as evidenced by a fair level of correlation [33]. This may indicate that children with SBM have a central timing impairment.…”

“…Researchers compared perceptual timing and motor timing in children with and without SBM [33]. Children with SBM had significantly more difficulty than age-matched controls on judging the duration of a timing task of 400ms duration.…”

The Cerebellum in Chiari Type II Malformation

“…One study reported smaller cerebellar volumes in 52 children with SB compared with 16 age-matched controls using volumetric analysis on MRI [41] . The study also reported that the cerebellar gray and white matter volumes were both reduced, and the reduction was greater in children with high spinal lesion levels than in children with low spinal lesion levels.…”

“…Thus, positioning anatomical markers across different scans for the purpose of averaging them is also difficult. Volumetric brain analysis using MRI in CII has been performed in one study [41] . It showed smaller cerebellar volumes in children with CII in comparison to age-matched controls [41] .…”

Verb generation in children with spina bifida

“…The T2-weighted scan was then clustered to extract cerebrospinal fluid (CSF) vol- Verb generation in children with spina bifida 183 umes, and the latter was used to adjust the white and gray matter volume measures obtained from the T1-weighted scan. The quantitative segmentation procedure is described in Dennis et al (2004) and Fletcher et al (2005) and in Appendix A.…”