Synopsis
Cerebellar networks show long-term plasticity and motor
training has been shown to change cerebellar microstructure and cortical
thickness. We used a combination of neuroimaging measures to visualise plastic changes in drumming - a
demanding multilimb training method: cerebellar
lobular volume and shape analysis, cortical thickness and diffusion tensor
imaging. Drum training
reorganises and reshapes the posterior cerebellum, expanding to connected parietal
and prefrontal cortical structures through the inferior cerebellar white matter
pathway. Thus, it may offer a novel method for cerebellar and cortical
plasticity, relevant as an intervention method for
psychiatric disorders
connected to cerebellar dysfunction, including autism spectrum disorder.Introduction
The cerebellum
is capable of experience-dependent plasticity and is highly involved
in learning processes.
1 Indeed, cerebellar networks show
long-term plasticity,
2 and motor training changes cerebellar microstructure.
Cerebellar learning
occurs in two stages, where cerebellar internal reorganisation is followed by
plastic changes in the cerebral cortex.
3 Specifically, motor training has been shown to increase posterior
cerebellar volume and cortical thickness of parietal and frontal regions, and/
or change white matter microstructure of the inferior cerebellar peduncles.
4,5 Thus, we used a combination of measures to visualise
plastic changes, namely shape analysis, cortical thickness and diffusion tensor
imaging (DTI) in addition to traditional
volume analysis on a demanding multilimb training method.
Methods
Sample. Thirty-one right-handed age-
and gender-matched healthy volunteers (16-19 years) with no prior drumming
experience and no psychiatric or neurological disorders were randomly assigned
to a drumming or
control group. Following the first drumming assessment and scanning session (T1), the
drumming group took part in 3x30-minute
drumming sessions per week for 8 weeks. Drumming was assessed on
the participants’ ability to play two
well known but not
previously practiced songs. A
High-Hat, Ride and
Snare (HRS) measurement determined drumming precision. Both
groups were scanned after the 8-week interval (T2).
Structural Analysis. Structural T1-weighted volumetric images were acquired
with full-head coverage, 196 contiguous slices (1.2mm slice thickness), a 256 x
256 matrix, and a repetition time/echo time (TR/TE) of 7.3/3ms (FA =11°, FOV = 270mm²).
Regional volume of the
cerebellum was calculated using the SUIT toolbox6 of the SPM12 software. For shape analysis of the cerebellum, the FSL FIRST software version
5.0.86 was used.7 The
FreeSurfer analysis suite version 5.3.0 was used to derive models of the cortical surface in each T1-weighted image. The results were
inspected and checked for quality following the ENIGMA protocol (www.enigma.ini.usc.edu).
DTI Analysis. Diffusion Tensor Imaging data was acquired
using a spin-echo echo-planar imaging (SE-EPI) sequence providing
full-head coverage with the following parameters: TE=78.5ms, TR=12 RR interval,
FOV=256x256, matrix=128x128, 72 slices with a thickness of 2mm making
an isotropic voxel of 2.0x2.0x2.0mm.
Diffusion weighting was applied along 60 uniformly distributed directions, 6 b0s and with a b-value of 1500s/mm2 and preprocessing was done
using ExploreDTI.8 Fractional Anisotropy (FA) and Mean Diffusivity (MD) maps were
generated and TrackVis was used for manual dissection and quantification
fibre tracts of the cerebellar tracts, using a manual
two regions-of-interest selection method.9 Inclusion regions-of-interest were: medulla oblongata until the level
of the dentate (inferior cerebellar peduncle); pontine nucleus until entrance
of the cerebellar hemispheres (middle cerebellar peduncle); dentate nucleus
until the entrance of the tegmentum in the mesencephalon (superior cerebellar
peduncle).
Statistical Analysis. Repeated measures ANOVAs determined changes over time, while univariate
ANCOVAs identified specific regions that significantly differed after drum
training. Gender was included as covariate and results were Bonferroni corrected for multiple comparisons.
Results and Discussion
Drum
training had a significant time x behaviour x group (
F(3,24) = 3.415,
p
= .034) effect.
To play on the beat,
drumming requires translating visuospatial and temporal information into motor
coordination, motor execution and planning
actions. Left VIIIa
volume increased (
F(2,24) = 5.980,
p = .012) and was
positively correlated with drum precision (
τ = .390,
p = .042), indicating
controlled action execution
11 remains a central active feature of drumming,
which has been strengthened.
Vermis Crus I (
F(2,24)
=
4.103,
p
=
.039) and VIIIb volume (left:
F(2,24) = 6.368,
p = .009; right:
F(2,24) = 5.199, p = .012) decreased,
suggesting a process of automaticity and efficiency.
12 In a previous study using the same population, Crus I/II showed a
decreased functional connectivity (FC) while
cortical regions showed an increased FC,
13 suggesting a plastic change affecting both cerebellar and cortical
regions. FA increases (left
ICP:
F(2,24) = 5.583,
p = .018; right ICP:
F(2,24) =
4.466,
p = .048) while MD decreases (right ICP:
F(2,24) = 4.539,
p
= .045) in the inferior cerebellar peduncle,
reflecting such plastic changes.
Parietal
and prefrontal cortical thickness regions responsible for planning actions
14 (right precuneus:
F(2,24) = 4.264,
p
= .050), motor sequencing
15 (left paracentral gyrus:
F(2,24) = 5.103,
p
= .026) and executive processing
16 (right superior frontal gyrus:
F(2,24) = 3.385,
p
= .049) increase after drum training.
Conclusion
Drum
training reorganises and reshapes the posterior cerebellum through plasticity, expanding to connected parietal and prefrontal cortical structures
through the inferior cerebellar white matter pathway. Thus, it may offer a
novel method for cerebellar and cortical plasticity, relevant
as an intervention method for psychiatric disorders connected to cerebellar dysfunction, including
autism spectrum disorder.
17,18Acknowledgements
The authors would
like to thank The Waterloo Foundation, NIHR Biomedical Research Centre for Mental Health at
the South London and the Maudsley NHS Foundation Trust and Institute of
Psychiatry, Kings College London. M. B. has received funding from the
European Community’s Seventh Framework (FP7/2007-2013) TACTICS. A. A. held a postdoctoral fellowship from the
"Fondation Thérèse et René Planiol".References
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