Experimental Brain Research (2018) 236:859–865
Somatosensory modulation of perceptual vestibular detection
· Anne Steinberg
· Elisa Raaella Ferrè
Received: 9 July 2017 / Accepted: 3 January 2018 / Published online: 22 January 2018
© Springer-Verlag GmbH Germany, part of Springer Nature 2018
Vestibular-multisensory interactions are essential for self-motion, navigation and postural stability. Despite evidence suggest-
ing shared brain areas between vestibular and somatosensory inputs, no study has yet investigated whether somatosensory
information inﬂuences vestibular perception. Here, we used signal detection methods to identify whether somatosensory
stimulation might interact with vestibular events in a vestibular detection task. Participants were instructed to detect near-
threshold vestibular roll-rotation sensations delivered by galvanic vestibular stimulation in one-half of experimental trials.
A vibrotactile signal occurred to the index ﬁngers of both hands in half of the trials, independent of vestibular signals. We
found that vibrotactile somatosensory stimulation decreased perceptual vestibular sensitivity. The results are compatible
with a gain regulation mechanism between vestibular and somatosensory modalities.
Keywords Vestibular sensation · Somatosensory processing · Galvanic vestibular stimulation · Multisensory modulation.
GVS Galvanic vestibular stimulation
PIVC Parieto insular vestibular cortex
SII Secondary somatosensory cortex
L-GVS Left-anodal and right-cathodal GVS
R-GVS Right-anodal and left-cathodal GVS
L-SHAM Left-anodal and right-cathodal SHAM
R-SHAM Right-anodal and left-cathodal SHAM.
Vestibular signals are strongly integrated with information
from other sensory modalities, including muscles, joints,
vision, and touch (Lackner and DiZio 2005). The vestibu-
lar system contains two distinct structures: the semicircu-
lar canals and the otolith organs, which are situated in the
inner ear and detect changes in angular and linear accelera-
tion, including gravity. Both semicircular canals and otolith
organs constantly provide information to the brain regarding
the sense of orientation and motion in three-dimensional
space. Thus, vestibular signals are crucial to the perception
of our body in the environment.
Unlike with all other sensory modalities, vestibular pro-
cessing is strongly multimodal. Interactions between the
canals and otoliths inputs occur immediately at the level
of the ﬁrst synapse in the brainstem and cerebellum. Mul-
timodal interactions between visual, somatosensory and
vestibular signals have been described in almost all vestibu-
lar relays, including the vestibular nuclei, the thalamus and
several areas in the cerebral cortex (Lopez et al. 2012; zu
Eulenburg et al. 2012). Electrophysiological studies have
identiﬁed a widespread vestibular network whose core area
is the Parieto Insular Vestibular Cortex (PIVC) (Guldin and
Grüsser 1998; Chen et al. 2010). This area lies in the poste-
rior parietal operculum extending into the posterior insular
lobe (Guldin and Grüsser 1998). The human homologue of
the primate PIVC is a distributed set of regions including
the anterior and posterior insula, superior temporal gyrus,
temporoparietal junction, inferior parietal lobule, and soma-
tosensory cortices (Lopez et al. 2012; zu Eulenberg et al.
2012). The right parietal operculum (area OP2) is consid-
ered the core region of the human cortical vestibular network
(zu Eulenburg et al. 2012).
Somatosensory areas also receive vestibular inputs. Elec-
trophysiological studies demonstrated that stimulating the
peripheral vestibular nerve triggered neuronal responses
in the secondary somatosensory cortex (SII) (Fredrickson
et al. 1966). Guldin and Grüsser (1998) estimated that about
Katerina Cabolis and Anne Steinberg equally contributed.
* Elisa Raﬀaella Ferrè
Department of Psychology, Royal Holloway University
of London, Egham, Surrey TW20 0EX, UK