The Effect of Galvanic Vestibular Stimulation on Visuospatial Cognition in an Incomplete Bilateral Vestibular Deafferentation Mouse Model

Abstract

ObjectivesTo evaluate the efficacy of galvanic vestibular stimulation (GVS) for recovering from the locomotor and spatial memory deficits of a murine bilateral vestibular deafferentation (BVD) model.MethodsMale C57BL/6 mice (n = 36) were assigned to three groups: bilateral labyrinthectomy with (BVD_GVS group) and without (BVD_non-GVS group) the GVS intervention, and a control group with the sham operation. We used the open field and Y maze, and Morris water maze (MWM) tests to assess locomotor and visuospatial cognitive performance before (baseline) and 3, 7, and 14 days after surgical bilateral labyrinthectomy. For the GVS group, a sinusoidal current at the frequency at 1 Hz and amplitude 0.1 mA was delivered for 30 min daily from the postoperative day (POD) 0 to 4 via electrodes inserted subcutaneously close to both the bony labyrinths.ResultsShort-term spatial memory was significantly impaired in bilaterally labyrinthectomized mice (BVD_non-GVS group), as reflected by decreased spontaneous alternation performance in the place recognition test and time spent in the novel arm and increased same arm return in the Y-maze test, compared with the control. Long-term spatial memory was also impaired, as indicated by a longer escape latency in the hidden platform trial and a lower percentage of time spent in the target quadrant in the probe trial of the MWM. GVS application significantly accelerated the recovery of locomotion and short-term and long-term spatial memory deficits in the BVD mice.ConclusionsOur data demonstrate that locomotion, short-term, and long-term (at least 2 weeks) spatial memory were impaired in BVD mice. The early administration of sinusoidal GVS accelerated the recovery of those locomotion and spatial memory deficiencies. GVS could be applied to patients with BVD to improve their locomotion and vestibular cognitive functioning.

Central vestibular networking for sensorimotor control, cognition, and emotion

“…Over the last decades, especially in the last 3 years, there has been increasing evidence from studies in animals [50][51][52] and humans [53][54][55][56] that the central vestibular system has numerous connections with brain areas related to memory, such as thalamic head direction cells, hippocampal place cells, and entorhinal grid cells [57 & ]. Disorders of 'higher' vestibular functions involve more than one sensory modality and cognitive domain and include, for example, hemispatial neglect and room-tilt illusion with a less favourable course if elicited by lesions in the vestibular-dominant right hemisphere [58].…”

Vestibular contribution to spatial orientation and navigation

“…Recently, it could be shown that the implantation of a vestibular prosthesis can inversely improve spatial orientation in animals with vestibular deficits [ 22 ]. Galvanic vestibular stimulation in mice had some effect on visuospatial cognition, if the bilateral peripheral vestibular deficits were incomplete [ 23 ▪ ]. However, it is unclear how persistent such an effect would be, as repetitive subthreshold noisy galvanic vestibular stimulation (nGVS) in rats with incomplete bilateral vestibular loss had no enduring effect on the movement pattern in an open field and no modulatory effects on hippocampal energy metabolism in vivo [ 24 ▪ ].…”