as cognitive impairment and depression. White matter hyperintensity are more than often present with vascular dementia, particularly among small vessel/subcortical subtypes of vascular dementia. Volume Smaller volumes (in terms of group averages) of white matter might be associated with larger deficits in attention, declarative memory, executive functions, intelligence, and academic achievement. However, volume change is continuous throughout one's lifetime due to neuroplasticity, and is a contributing factor rather than determinant factor of certain functional deficits due to compensating effects in other brain regions. The integrity of white matter declines due to aging. Nonetheless, regular aerobic exercise appears to either postpone the aging effect or in turn enhance the white matter integrity in the long run. Changes in white matter volume due to inflammation or injury may be a factor in the severity of obstructive sleep apnea. Imaging The study of white matter has been advanced with the neuroimaging technique called diffusion tensor imaging where magnetic resonance imaging (MRI) brain scanners are used. As of 2007, more than 700 publications have been published on the subject. A 2009 paper by Jan Scholz and colleagues used diffusion tensor imaging (DTI) to demonstrate changes in white matter volume as a result of learning a new motor task (e.g. juggling). The study is important as the first paper to correlate motor learning with white matter changes. Previously, many researchers had considered this type of learning to be exclusively mediated by dendrites, which are not present in white matter. The authors suggest that electrical activity in axons may regulate myelination in axons. Or, gross changes in the diameter or packing density of the axon might cause the change. A more recent DTI study by Sampaio-Baptista and colleagues reported changes in white matter with motor learning along with increases in myelination. See also White matter dissection Ventriculomegaly Vascular dementia Vanishing white matter disease Brain atrophy References Further reading External links Central nervous system Neuroanatomy