OBJECTIVETo study human vestibular cerebral representations by combining right-sided ice-water stimulation at 0 degree C with blood oxygenation level dependent functional magnetic resonance imaging (BOLD-fMRI) and to evaluate the value of this method in the functional localization of human vestibular cortex.

METHODSTwenty right-handed volunteers (12 men and 8 women) received unilateral irrigation of the right external auditory meatu for 15 s with 15 ml of water at 0 degrees C during fMRI in complete darkness. The functional imaging of brain cortex was acquired with a 1.5-T MRI scanner (Signa Infinity Twin + Excite; General Electric Co., USA). The successive functional images from each subject were analyzed as a group with statistical parametric mapping software (SPM 99).

RESULTSUltimately, data obtained from 17 subjects were analyzed (3 subjects were eliminated from data because of head movement exceeding 2 mm). The group analysis showed bilateral (particularly left-sided) cortical activation, associated with caloric stimulus involving in temporoparietal junction extending into the posterior insula, supramarginal gyrus in the inferior parietal lobe, precuneus, supplementary motor area (SMA), the ventrolateral portion of the occipital lobe, cuneus and lingual gyrus, superior temporal gyrus and cingular cortex.

CONCLUSIONSIce-water stimulation at 0 degree C in fMRI reveals a widespread cortical network involved in vestibular signal processing in human. As the functional localization of vestibular cortex could be determined precisely, ice-water stimulation at 0 degree C in fMRI would hold great promise as a sensitive and reproducible tool for the research in human vestibular cortex.