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Neuroplastic changes within the brains of manganese-exposed welders: recruiting additional neural resources for successful motor performance
  1. Yongmin Chang1,2,
  2. Hui-Jin Song3,
  3. Jae-Jun Lee3,
  4. Jee-Hye Seo3,
  5. Joo-Hyun Kim3,
  6. Hui Joong Lee2,
  7. Hye Jung Kim2,
  8. Yangho Kim4,
  9. Joon-Ho Ahn5,
  10. Sin-Jae Park5,
  11. Jee Hyun Kwon6,
  12. Kyoung Sook Jeong7,
  13. Doo-Kyo Jung8
  1. 1Department of Molecular Medicine, Kyungpook National University College of Medicine, Kyungpook National University Hospital, Daegu, South Korea
  2. 2Department of Radiology, Kyungpook National University College of Medicine, Kyungpook National University Hospital, Daegu, South Korea
  3. 3Department of Medical and Biological Engineering, Kyungpook National University, Daegu, South Korea
  4. 4Department of Occupational and Environmental Medicine, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, South Korea
  5. 5Department of Psychiatry, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, South Korea
  6. 6Department of Neurology, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, South Korea
  7. 7Department of Occupational and Environmental Medicine, Dongguk University-Seoul, Graduate School of Medicine, Goyang, South Korea
  8. 8Department of Neurology, Kyungpook National University College of Medicine, Kyungpook National University Hospital, Daegu, South Korea
  1. Correspondence to Yangho Kim, Department of Occupational and Environmental Medicine, Ulsan University Hospital, University of Ulsan College of Medicine, # 290-3 Cheonha-Dong, Dong-Gu, Ulsan 682-060, South Korea; yanghokm{at}nuri.net

Abstract

Background In a previous study, regional delivery of manganese (Mn)ions within the brain revealed that the metal accumulates in the basal ganglia, where it induces degeneration of the globus pallidus. Degeneration of the basal ganglia impairs motor ability by compromising an important neural circuit involved in the regulation of motor control. Therefore, much research has been devoted to identifying a sensitive and non-invasive imaging marker to evaluate the functional correlates of Mn-related brain dysfunction.

Methods We performed the first-ever sequential finger-tapping functional MRI (fMRI) experiment to investigate the behavioural significance of additionally recruited brain regions in welders with chronic Mn exposure.

Results During the finger tapping task, activation of the bilateral primary sensorimotor cortex (SM1), bilateral supplementary motor area (SMA), bilateral dorsolateral premotor cortex, bilateral superior parietal cortex and ipsilateral dentate nucleus was higher in the welding group (42 welders) than in the control group (26 controls). The pallidal index correlated with the activation observed in the contralateral SM1 for the finger tapping task of the left hand. The fMRI variables correlated with motor behaviour. Grooved Pegboard performances (right hand) correlated with activation, as seen in the ipsilateral and contralateral SMAs obtained during the finger tapping task of the right hand.

Conclusion Our findings suggest that increased brain activation results from the compensational activation of ancillary cortical pathways, which ensures adequate motor function.

  • Manganese (Mn)
  • neurotoxin
  • functional MRI (fMRI)
  • welder
  • motor deficit
  • Occupational health practice
  • Toxicology
  • Neurobehavioural effects
  • Metals
  • Welding

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Footnotes

  • Yongmin Chang and Hui-Jin Song contributed equally to this work.

  • Funding This work was supported by a Korea Science and Engineering Foundation (KOSEF) grant funded by the Korean government (MEST) (no. R01-2007-000-20540-0).

  • Competing interests None.

  • Ethics approval This study was conducted with the approval of Ulsan University Hospital.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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