title: Investigating structural plasticity in musicians’ brains using structural magnetic resonance and diffusion tensor imaging techniques
Creators: name: Abdul-kareem, Ihssan
Publisher: name: University of Liverpool Repository
Year: 2013

description: Neuroplasticity is the ability of the brain to change its structure and/or function in response to environmental stimuli. It is implicated in many processes, such as learning, maturation, skill acquisition, and rehabilitation following brain injury. With the advent of neuroimaging techniques, the study of neuroplasticity and its mechanisms have fascinated researchers given the wide scope with which this process is involved. Musicians have long been considered an ideal model to study neuroplasticity in humans. It has been shown that musicians with their early, intensive, and multimodal skilful practice have structural plasticity in different brain regions. The objective of this work was to extend these structural studies through examining different cohorts of musicians, using a multitude of imaging and morphometric techniques, and performing novel examinations of brain regions essential for enabling high level musical performance such as Broca’s area, corpus callosum (CC), and cerebellum. Three age-, gender- and handedness-matched cohorts were examined. The first cohort included 26 orchestral musicians and 26 non-musicians. High resolution T1-weighted structural MR images were acquired to measure gray and white matter volumes and cortical surface area of Broca’s area subparts: pars opercularis/BA44 and pars triangularis/BA45. The second cohort included 12/12/12 professional musicians/amateur musicians/non-musicians. High resolution T1-weighted MR images were acquired to measure cross-sectional areas of four regions of the midsagittal CC: CC1 (rostrum/ genu/anterior body), CC2 (anterior midbody), CC3 (posterior midbody), and CC4 (isthmus and splenium). In the third cohort, 12/12 musicians and non-musicians were examined. High resolution T1-weighted structural MR images were acquired to measure cross-sectional areas of CC1-CC4 regions; and diffusion tensor imaging-based tractography was used to measure average fractional anisotropy (FA), mean diffusivity (MD), tract volume, and number of streamlines of the same regions. In a subset (10/10) of this cohort, high resolution structural scans were used to measure gray and white matter volumes of cerebellar hemispheres; and diffusion tensor imaging-based tractography was used to measure average FA, tract volume, and number of streamlines of superior (SCP) and middle (MCP) cerebellar peduncles. Outcome measures were compared between groups. Compared to controls, musicians possessed greater gray matter volume and cortical surface area of left pars opercularis/BA44 in the first cohort. The volume of left pars opercularis was positively correlated with years of musical performance. Professional musicians possessed greater cross-sectional area of CC1 and CC4 regions compared to amateurs and non-musicians in the second cohort. In the third cohort, musicians possessed greater cross-sectional area, average FA/tract volume/number of streamlines, and lower MD in CC4 region. There was a negative correlation between cross-sectional area of CC4 region and age of starting musical training. There was a positive correlation between average FA values and cross-sectional area of CC4 region in all subjects. In addition, musicians had increased white matter volume of the right cerebellar hemisphere, increased tract volume and number of streamlines of right SCP, and tract volume of right MCP. I hypothesize that these findings represent use-dependent structural plasticity imposed by musical performance. At the microscopic level, these macroanatomical changes may reflect increased synaptogenesis and dendritic growth, generation of new axon collaterals, and formation of new neurons, which would support enhanced functional demands on musicians’ brains.