Tuesday, March 23, 2010

Brain changes caused by forced right-handedness

Klöppel et al. make the interesting observation that plastic changes occur not only in primary sensory-motor cortex but also deep structures of the brain in adult "converted" left-handers who were forced as children to become dextral writers:
Does a conflict between inborn motor preferences and educational standards during childhood impact the structure of the adult human brain? To examine this issue, we acquired high-resolution T1-weighted magnetic resonance scans of the whole brain in adult "converted" left-handers who had been forced as children to become dextral writers. Analysis of sulcal surfaces revealed that consistent right- and left-handers showed an interhemispheric asymmetry in the surface area of the central sulcus with a greater surface contralateral to the dominant hand. This pattern was reversed in the converted group who showed a larger surface of the central sulcus in their left, nondominant hemisphere, indicating plasticity of the primary sensorimotor cortex caused by forced use of the nondominant hand. Voxel-based morphometry showed a reduction of gray matter volume in the middle part of the left putamen in converted left-handers relative to both consistently handed groups. A similar trend was found in the right putamen. Converted subjects with at least one left-handed first-degree relative showed a correlation between the acquired right-hand advantage for writing and the structural changes in putamen and pericentral cortex. Our results show that a specific environmental challenge during childhood can shape the macroscopic structure of the human basal ganglia. The smaller than normal putaminal volume differs markedly from previously reported enlargement of cortical gray matter associated with skill acquisition. This indicates a differential response of the basal ganglia to early environmental challenges, possibly related to processes of pruning during motor development.

1 comment:

  1. Isaac Osobukola4:08 PM

    Hi, I’m Isaac Osobukola, a year 12 student. I am researching into effects of forced change on handedness. Do you really change your natural handedness? To do this I need to collect a lot of data from those who have not been forced to change their handedness and those who have. I assure you that any data you provide is strictly confidential and would not be passed to any 3rd party. Please fill in this quick survey. Thanks for your cooperation. :)