Galvanic vestibular stimulation activates the parietal and temporal cortex in humans: A functional near‐infrared spectroscopy (fNIRS) study

• Published in: The European journal of neuroscience Vol. 58; no. 1; pp. 2267 - 2277
• Main Authors: Hernández‐Román, Joaquin, Montero‐Hernández, Samuel, Vega, Rosario, Orihuela‐Espina, Felipe, Soto, Enrique
• Format: Journal Article
• Language: English
• Published: France Wiley Subscription Services, Inc 01.07.2023
• Subjects: Balance; Blood pressure; Body temperature; Capacitance; Cerebral cortex; Cortex (parietal); Cortex (temporal); cortical; fNIRS; GVS; haemodynamic; Heart rate; Hemoglobin; Infrared spectroscopy; posture; Spectrum analysis; vestibular; Vestibular system; fNIRS; GVS; vestibular; haemodynamic; posture; cortical
• ISSN: 0953-816X; 1460-9568; 1460-9568
• DOI: 10.1111/ejn.16041

Galvanic vestibular stimulation (GVS) helps stabilize subjects when balance and posture are compromised. This work aimed to define the cortical regions that GVS activates in normal subjects. We used functional near‐infrared spectroscopy (fNIRS) to test the hypothesis that GVS activates similar cortical areas as a passive movement. We used transcranial current stimulation (cathode in the right mastoid process and anode in the FPz frontopolar point) of bipolar direct current (2 mA), false GVS (sham), vibration (neutral stimulus), and back and forth motion (positive control of vestibular movement) in 18 clinically healthy volunteers. Seventy‐two brain scans were performed, applying a crossover‐type experimental design. We measured the heart rate, blood pressure, body temperature, head capacitance, and resistance before and after the experiment. The haemodynamic changes of the cerebral cortex were recorded with an arrangement of 26 channels in four regions to perform an ROI‐level analysis. The back‐and‐forth motion produced the most significant oxygenated haemoglobin (HbO2) increase. The response was similar for the GVS stimulus on the anterior and posterior parietal and right temporal regions. Sham and vibrational conditions did not produce significant changes ROI‐wise. The results indicate that GVS produces a cortical activation coherent with displacement percept. We used functional near‐infrared spectroscopy (fNIRS) to test the hypothesis that galvanic vestibular stimulation (GVS) activates similar cortical areas as a passive movement in healthy humans. The haemodynamic changes of the cerebral cortex were recorded with an arrangement of 26 channels for the fNIRS, grouped into four regions of interest (ROI). Each subject was randomly simulated with GVS, sham GVS, hand vibration, and back‐and‐forth passive movement. The back‐and‐forth motion produced the most significant haemodynamic change in the cerebral cortex. The response was similar for the GVS stimulus. Sham and vibrational conditions did not generate significant changes. Our results show that GVS produced a cortical response that resembles passive movement.