The swallow-related cortical areas in healthy adults: an founctional MRI study

Abstract

Objective To investigate the swallow-related brain areas in normal adults with different experimental swallow tasks using founctional MRI (fMRI). Methods Eight healthy volunteers received volitional and reflexive water swallowing during fMRI studies. SPM2 software was used to postprocess functional data and display activated brain mapping. Paired t-test was used to compare the activated brain volume and increased signal of each hemisphere in two swallowing tasks. Results Bilateral primary sensorimotor cortex, premotor cortex, anterior cingnlated gyrus, insular, prefrontal area, posterior parietal lobe, temporal gyms , basal ganglion and cerebellum were detected in volitional water swallowing. However, only few brain areas such as bilateral primary sensorimotor cortex, posterior parietal lobe, frontal opercnlum were activated in reflexive water swallowing task. Volitional swallowing tasks activated much more brain volumes [1213±110 (left) and 1969±133 (right) vs 488±45 (left) and 398±35 (right), in pixels] and increase in signals [4.4±0.4 (left) and 4.1±0.2 (right) vs 2.6±0.3 (left) and 2.5±1.2 (right) at sensorimotor areas, 1.2±0.5 (left) and 1.5±0.6 (right) vs 0.6±0.4 (left) and 0.2±0.1 (right) at insular lobes] than those in reflexive tasks. Different lateralization in activation brain area was observed in swallowing tasks. Lateral index was ( - 16 ±9) % and ( 11 ±5 ) % respectively in volitional and reflexive water swallowing tasks. Conclusions Volitional swallowing task activates much more brain regions and brain volumes as compared to reflexive tasks. The different activated regions between volitional and reflexive swallowing tasks maybe relate to brain activities such as intent, planning, urge and possibly passion during volitional swallowing. Key words: Swallow; Magnetic resonance imaging; Function; Volition; Reflex