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Characteristics of the aberrant pyramidal tract in comparison with the pyramidal tract in the human brain

Hyeok Gyu Kwon1, Su Min Son1, Min Cheol Chang1, Saeyoon Kim2, Yong Hyun Kwon3 and Sung Ho Jang1*

Author Affiliations

1 Department of Physical Medicine and Rehabilitation, College of Medicine, Yeungnam University, Daegu, Republic of Korea

2 Department of Pediatrics, College of Medicine, Yeungnam University, Daegu, Republic of Korea

3 Department of Physical Therapy, Yeungnam College of Science & Technology, Daegu, Republic of Korea

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BMC Neuroscience 2011, 12:108  doi:10.1186/1471-2202-12-108

Published: 1 November 2011



The aberrant pyramidal tract (APT) refers to the collateral pathway of the pyramidal tract (PT) through the medial lemniscus in the midbrain and pons. Using diffusion tensor tractography (DTT), we investigated the characteristics of the APT in comparison with the PT in the normal human brain.


In thirty-four (18.3%, right hemisphere: 20, left hemisphere: 14) of the 186 hemispheres, the APTs separated from the PT at the upper midbrain level, descended through the medial lemniscus from the midbrain to the pons, and then rejoined with the PT at the upper medulla. Nine (26.5%) of the 34 APTs were found to originate from the primary somatosensory cortex without a primary motor cortex origin. Values of fractional anisotropy (FA) and tract volume of the APT were lower than those of the PT (P < 0.05); however, no difference in mean diffusivity (MD) value was observed (P > 0.05).


We found that the APT has different characteristics, including less directionality, fewer neural fibers, and less origin from the primary motor cortex than the PT.