Dynamic arm movements attenuate the perceptual distortion of visual vertical induced during prolonged whole-body tilt.
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ABSTRACT:
SUBMITTER: Tani K
PROVIDER: S-EPMC8087117 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:ObjectiveTo examine the validity of head roll-tilt subjective visual vertical (HT-SVV) in diagnosing persistent postural-perceptual dizziness (PPPD).Study designRetrospective review.SettingTertiary referral center.PatientsSixty-one patients with PPPD, 10 with unilateral vestibular hypofunction (UVH), and 11 with psychogenic dizziness (PD), showing chronic vestibular symptoms for >3 months.InterventionsHead-tilt perception gain (HTPG, i.e., mean perceptual gain [perceived/actual tilt angle]) during right or left head tilt of approximately 30° (HT-SVV) and conventional head-upright SVV (UP-SVV) were measured. Bithermal caloric testing, cervical and ocular vestibular-evoked myogenic potentials (cVEMP and oVEMP), and posturography were conducted.Main outcome measuresMultiple comparisons were performed for the HT-SVV and other vestibular tests among the disease groups. A receiver operating characteristic curve was created to predict PPPD using HTPG.ResultsHTPG was significantly greater in the PPPD group than in the UVH and PD groups. There were no significant differences in UP-SVV, cVEMP, oVEMP, and posturography (foam ratio and Romberg ratio on foam) among the disease groups, while the UVH group had the highest canal paresis compared to the other two groups. The area under the curve of the receiver operating characteristic curve for predicting PPPD was 0.764, and the HTPG value of 1.202 had a specificity of 95.2% for diagnosing PPPD.ConclusionsWhile conventional vestibular tests including UP-SVV, VEMPs, and posturography did not show abnormalities in PPPD, high HTPG in the HT-SVV test, an excessive perception of head tilt, can be a specific marker for discriminating PPPD from other chronic vestibular diseases.
| S-EPMC8584214 | biostudies-literature
Project description:Performing accurate actions such as goal-directed arm movements requires taking into account visual and body orientation cues to localize the target in space and produce appropriate reaching motor commands. We experimentally tilted the body and/or the visual scene to investigate how visual and body orientation cues are combined for the control of unseen arm movements. Subjects were asked to point toward a visual target using an upward movement during slow body and/or visual scene tilts. When the scene was tilted, final pointing errors varied as a function of the direction of the scene tilt (forward or backward). Actual forward body tilt resulted in systematic target undershoots, suggesting that the brain may have overcompensated for the biomechanical movement facilitation arising from body tilt. Combined body and visual scene tilts also affected final pointing errors according to the orientation of the visual scene. The data were further analysed using either a body-centered or a gravity-centered reference frame to encode visual scene orientation with simple additive models (i.e., 'combined' tilts equal to the sum of 'single' tilts). We found that the body-centered model could account only for some of the data regarding kinematic parameters and final errors. In contrast, the gravity-centered modeling in which the body and visual scene orientations were referred to vertical could explain all of these data. Therefore, our findings suggest that the brain uses gravity, thanks to its invariant properties, as a reference for the combination of visual and non-visual cues.
| S-EPMC4055731 | biostudies-literature
Project description:To measure the static visual vertical and the effect of visual rotation on the perception of visual vertical in migraine and vestibular migraine subjects. By so doing, we may better understand the vestibular contribution to the pathophysiology of migraine, as well as the capacity for visual compensation.The perception of visual vertical in the presence of static and dynamic visual cues was prospectively studied in 10 subjects with migraine, 6 subjects with vestibular migraines, and 10 controls. Subjects used a dial to rotate a fluorescent green line to the vertical position. Static visual vertical (SVV) was measured with a black background, as well as with a static random-dot visual pattern. This pattern was then rotated at various velocities to measure dynamic visual vertical (DVV).Migraine subjects had greater deviation from true vertical than controls in SVV (P < 0.05). The DVV in migraine subjects was greater than controls when rotated in the counterclockwise at -5°/s (P < 0.01), -20°/s (P < 0.01), and -80°/s (P < 0.01), but not when the line was rotated clockwise. Vestibular migraine subjects did not deviate significantly from controls in SVV (P < 0.37, P < 0.22), but did show greater deviation in the DVV tasks at -80 and -20°/s (P < 0.05, P < 0.03). Migraine and vestibular migraine subjects demonstrated a wider range of vertical deviance when compared to controls (P < 0.02).This study demonstrates a significant deviation of the perceived static as well as dynamic visual vertical in migraine subjects. Moving stimuli may have a greater influence on migraine and vestibular migraine subjects, which suggests an underlying sensory integration disorder.
| S-EPMC5544022 | biostudies-other
Project description:Humans maintain a stable representation of the visual world effortlessly, despite constant movements of the eyes, head, and body, across multiple planes. Whereas visual stability in the face of saccadic eye movements has been intensely researched, fewer studies have investigated retinal image transformations induced by head movements, especially in the frontal plane. Unlike head rotations in the horizontal and sagittal planes, tilting the head in the frontal plane is only partially counteracted by torsional eye movements and consequently induces a distortion of the retinal image to which we seem to be completely oblivious. One possible mechanism aiding perceptual stability is an active reconstruction of a spatiotopic map of the visual world, anchored in allocentric coordinates. To explore this possibility, we measured the positional motion aftereffect (PMAE; the apparent change in position after adaptation to motion) with head tilts of ?42° between adaptation and test (to dissociate retinal from allocentric coordinates). The aftereffect was shown to have both a retinotopic and spatiotopic component. When tested with unpatterned Gaussian blobs rather than sinusoidal grating stimuli, the retinotopic component was greatly reduced, whereas the spatiotopic component remained. The results suggest that perceptual stability may be maintained at least partially through mechanisms involving spatiotopic coding.NEW & NOTEWORTHY Given that spatiotopic coding could play a key role in maintaining visual stability, we look for evidence of spatiotopic coding after retinal image transformations caused by head tilt. To this end, we measure the strength of the positional motion aftereffect (PMAE; previously shown to be largely spatiotopic after saccades) after large head tilts. We find that, as with eye movements, the spatial selectivity of the PMAE has a large spatiotopic component after head rotation.
| S-EPMC5310234 | biostudies-literature
Project description:Perception of upright is often assessed by aligning a luminous line to the subjective visual vertical (SVV).Here we investigated the effects of visual line rotation and viewing eye on SVV responses and whether there was any change with head tilt.SVV was measured using a forced-choice paradigm and by combining the following conditions in 22 healthy subjects: head position (20° left tilt, upright and 20° right tilt), viewing eye (left eye, both eyes and right eye) and direction of visual line rotation (clockwise [CW] and counter clockwise [CCW]).The accuracy and precision of SVV responses were not different between the viewing eye conditions in all head positions (P> 0.05, Kruskal-Wallis test). The accuracy of SVV responses was % significantly different between the CW and CCW line rotations (p ? 0.0001; Kruskal-Wallis test) and SVV was tilted in the same direction as the line rotation. This effect of line rotation was however not consistent across head tilts and was only present in the upright and right tilt head positions. The accuracy of SVV responses showed a higher variability among subjects in the left head tilt position with no significant difference between the CW and CCW line rotations (P> 0.05; post-hoc Dunn's test).In spite of the challenges to the estimate of upright with head tilt, normal subjects did remarkably well irrespective of the viewing eye. The physiological significance of the asymmetry in the effect of line rotation between the head tilt positions is unclear but it %may suggest suggests a lateralizing effect of head tilt on the visual perception of upright.
| S-EPMC4890624 | biostudies-literature
Project description:Perceptual learning, the ability to improve the sensitivity of sensory perception through training, has been shown to exist in all sensory systems but the vestibular system. A previous study found no improvement of passive self-motion thresholds in the dark after intense direction discrimination training of either yaw rotations (stimulating semicircular canals) or y-translation (stimulating otoliths). The goal of the present study was to investigate whether perceptual learning of self-motion in the dark would occur when there is a simultaneous otolith and semicircular canal input, as is the case with roll tilt motion stimuli. Blindfolded subjects (n = 10) trained on a direction discrimination task with 0.2-Hz roll tilt motion stimuli (9 h of training, 1,800 trials). Before and after training, motion thresholds were measured in the dark for the trained motion and for three transfer conditions. We found that roll tilt sensitivity in the 0.2-Hz roll tilt condition was increased (i.e., thresholds decreased) after training but not for controls who were not exposed to training. This is the first demonstration of perceptual learning of passive self-motion direction discrimination in the dark. The results have potential therapeutic relevance as 0.2-Hz roll thresholds have been associated with poor performance on a clinical balance test that has been linked to more than a fivefold increase in falls.
| S-EPMC7297830 | biostudies-literature
Project description:Traditionally, brain-machine interfaces (BMIs) extract motor commands from a single brain to control the movements of artificial devices. Here, we introduce a Brainet that utilizes very-large-scale brain activity (VLSBA) from two (B2) or three (B3) nonhuman primates to engage in a common motor behaviour. A B2 generated 2D movements of an avatar arm where each monkey contributed equally to X and Y coordinates; or one monkey fully controlled the X-coordinate and the other controlled the Y-coordinate. A B3 produced arm movements in 3D space, while each monkey generated movements in 2D subspaces (X-Y, Y-Z, or X-Z). With long-term training we observed increased coordination of behavior, increased correlations in neuronal activity between different brains, and modifications to neuronal representation of the motor plan. Overall, performance of the Brainet improved owing to collective monkey behaviour. These results suggest that primate brains can be integrated into a Brainet, which self-adapts to achieve a common motor goal.
| S-EPMC4497496 | biostudies-literature
Project description:Myopia is significantly growing eye disease which accompanies various ocular pathologies including glaucoma. Understanding visual field (VF) and retinal nerve fiber layer (RNFL) damage observed in myopic eyes is important. Therefore, we evaluated optic disc margin anatomy using spectral-domain (SD) optical coherence tomography (OCT). We enrolled 40 healthy myopic patients and 64 myopic patients with RNFL defects in the superonasal region of the optic disc on red-free photographs and OCT. Optic disc stereophotographs were co-localized to SD-OCT images, and we analyzed the frequency with which the disc margin identified in photographs coincided with Bruch's membrane (BM) opening, BM/border tissue, or border tissue. For each scan, the presence of border tissue overhang beyond the clinical disc margin and the end of Bruch's membrane was identified. Among 64 myopic eyes with RNFL defects, 42 had corresponding inferotemporal VF defects. Border tissue overhang was found from 25 to 60% of myopic eyes with RNFL defect at all clock positions. However, border tissue overhang was found from 86 to 97% at 1, 2, 11 and 12 o'clock position in myopic eyes with VF defects. This was significantly different from myopic healthy eyes. We suggest that the OCT structure at the disc margin might contribute to VF damage in myopic patients.
| S-EPMC6401376 | biostudies-other
Project description:We continuously move our eyes when we inspect a visual scene. Although this leads to a rapid succession of discontinuous and fragmented retinal snapshots, we perceive the world as stable and coherent. Neural mechanisms underlying visual stability may depend on internal monitoring of planned or ongoing eye movements. In the macaque brain, a pathway for the transmission of such signals has been identified that is relayed by central thalamic nuclei. Here, we studied a possible role of this pathway for perceptual stability in a patient with a selective lesion affecting homologous regions of the human thalamus. Compared with controls, the patient exhibited a unilateral deficit in monitoring his eye movements. This deficit was manifest by a systematic inaccuracy both in successive eye movements and in judging the locations of visual stimuli. In addition, perceptual consequences of oculomotor targeting errors were erroneously attributed to external stimulus changes. These findings show that the human brain draws on transthalamic monitoring signals to bridge the perceptual discontinuities generated by our eye movements.
| S-EPMC2824294 | biostudies-literature
Project description:Most people easily learn to recognize new faces and places, and with more extensive practice they can become experts at visual tasks as complex as radiological diagnosis and action video games. Such perceptual plasticity has been thoroughly studied in the context of training paradigms that require constant fixation. In contrast, when observers learn under more natural conditions, they make frequent saccadic eye movements. Here we show that such eye movements can play an important role in visual learning. Observers performed a task in which they executed a saccade while discriminating the motion of a cued visual stimulus. Additional stimuli, presented simultaneously with the cued one, permitted an assessment of the perceptual integration of information across visual space. Consistent with previous results on perisaccadic remapping [M. Szinte, D. Jonikaitis, M. Rolfs, P. Cavanagh, H. Deubel, J. Neurophysiol. 116, 1592-1602 (2016)], most observers preferentially integrated information from locations representing the presaccadic and postsaccadic retinal positions of the cue. With extensive training on the saccade task, these observers gradually acquired the ability to perform similar motion integration without making eye movements. Importantly, the newly acquired pattern of spatial integration was determined by the metrics of the saccades made during training. These results suggest that oculomotor influences on visual processing, long thought to subserve the function of perceptual stability, also play a role in visual plasticity.
| S-EPMC7149482 | biostudies-literature