OBJECTIVETo investigate the neural representations of normal humans intraoral water stimulation using non-invasive functional magnetic resonance imaging (fMRI) measurement, provide information for intraoral thermosensory study.

METHODS13 healthy right-handed subjects (of which 6 were males) participated in the study to receive 23 degrees C deionized distilled water stimuli in mouth. The experimental protocol consisted of a block-design using 5 stimulus. Water stimuli were delivered to the subject's mouth through self-made polythene tubes that were held between lips. Functional MRI scan covering the whole brain was carried out. The fMRI data was analyzed by SPM99 software with statistic t-test to generate the activation map.

RESULTSSignificant activations existed in peri-sylvian including pre/ post-central gyrus, insular, orbitalfrontal cortex (OFC), anterior cingulate cortex (ACC), frontal gyrus, parietal lobule, midbrain and parietal lobule.

CONCLUSIONWater's ability to activate nonspecific somatosensory, thermal or taste processing. The findings highlight the complex and distributed processing of different aspects of intraoral perception, and emphasize the importance of controlling for the effects of water when investigating the functional neuroanatomy of taste or temperature.