occurrence of a unilateral stroke. Although the number of
patients studied is too small for firm conclusions to be made,
these observations may have implications for the diagnosis,
prognosis and treatment of stroke related dysphagia.
Considering the brain’s plasticity, and our observations of the
changes to these functional maps, a novel insight from our work
is that increased bilateral activation may indicate a good
prognosis for acute mild or moderate strokes. Furthermore,
improvement in the dysphagia of stroke patients may be
associated with a compensatory recruitment and bilateral
activation of areas that are involved in the cortical representa-
tion of swallowing.
The present study has several limitations. For dysphagic
stroke patients, it may be difficult to complete the water bolus
swallowing task in the supine position. Taking the safety of
patients and older controls into consideration, we only used the
dry swallowing task in this pilot study. Furthermore, these
experimental tests do not accurately represent ‘‘normal’’
swallowing conditions. Subjects were required to swallow
repeatedly while lying supine, for several seconds. Due to the
strict training before study, all subjects showed swallow related
movements, as determined by EMG. Although possible con-
founding variables such as age, lesion location and disease
duration were carefully matched between groups, we acknowl-
edge the modest sample size of this study and recognise that a
large cohort study would be required to verify the current
In conclusion, the fMRI scanning results indicate that the
primary motor and somatosensory areas are consistently active
across healthy adult subjects when swallowing. The anterior
cingulate and insular cortices are also highly active during
swallowing. To further our understanding of the function of
these anatomical regions and systems in swallowing, we
demonstrated that swallowing function in dysphagic stroke
patients is associated with a compensatory recruitment and
activation of regions of the cerebral cortex in the intact
hemisphere. Given that the intact hemisphere plays an
important role in the recovery of swallowing after a stroke,
we are provided with an interesting opportunity to study the
plasticity of an intact pathway. Thus any future rehabilitation
therapies aimed at enhancing the recovery of swallowing should
target reorganisation of the intact side.
Finally, functional MRI is among the fastest growing brain
imaging technologies. It is advantageous because it is minimally
invasive, compared with some other brain imaging systems, and
it is also becoming increasingly accessible to researchers. As a
valuable method for studying swallowing control, this approach
allows assessment of the cerebral activity associated with
functional swallowing, and could serve as a useful prognos-
ticator for dysphagic stroke conditions.
Acknowledgements: The authors acknowledge support from the State Key Lab of
Biotherapy, West China Hospital/West China Medical School of Sichuan University.
We thank all of the participants for their cooperation during the period of the ‘‘5.12’’
earthquake. We are also most grateful to Wei Liao, PhD, for his collaboration and
Funding: This research was supported by the National Natural Science Foundation of
China (grant Nos 30625024, 30728017, 30525030 and 60736029), Key research
project of science and technology of MOE (107097), National Basic Research
Programme of China (973 Programme No 2007CB512305), National High Technology
Programme of China (863 Programme No 2008AA02Z408 and 2007AA02Z482), the
Programme of State Administration of Traditional Chinese Medicine of Zhejiang
Province (No 2006Y016), the Construction Project of Medical Key Subject in Zhejiang
Province of China (Rehabilitation Medicine, 2007.7–2010.7).
Competing interests: None.
Ethics approval: The study protocol was approved by the institutional ethics
committee at Sichuan University.
Provenance and peer review: Not commissioned; externally peer reviewed.
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