visual dependence
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2021 ◽  
Vol 10 (18) ◽  
pp. 4274
Author(s):  
Iole Indovina ◽  
Luca Passamonti ◽  
Viviana Mucci ◽  
Giuseppe Chiarella ◽  
Francesco Lacquaniti ◽  
...  

Persistent postural-perceptual dizziness (PPPD), defined in 2017, is a vestibular disorder characterized by chronic dizziness that is exacerbated by upright posture and exposure to complex visual stimuli. This review focused on recent neuroimaging studies that explored the pathophysiological mechanisms underlying PPPD and three conditions that predated it. The emerging picture is that local activity and functional connectivity in multimodal vestibular cortical areas are decreased in PPPD, which is potentially related to structural abnormalities (e.g., reductions in cortical folding and grey-matter volume). Additionally, connectivity between the prefrontal cortex, which regulates attentional and emotional responses, and primary visual and motor regions appears to be increased in PPPD. These results complement physiological and psychological data identifying hypervigilant postural control and visual dependence in patients with PPPD, supporting the hypothesis that PPPD arises from shifts in interactions among visuo-vestibular, sensorimotor, and emotional networks that overweigh visual over vestibular inputs and increase the effects of anxiety-related mechanisms on locomotor control and spatial orientation.


2021 ◽  
Vol 10 (17) ◽  
pp. 3787
Author(s):  
Augusto Pietro Casani ◽  
Francesco Lazzerini ◽  
Ottavia Marconi ◽  
Nicola Vernassa

(1) Background: Visually induced vertigo (i.e., vertigo provoked by moving visual scenes) can be considered a noticeable feature of vestibular migraines (VM) and can be present in patients suffering from acute unilateral vestibulopathy (AUV). Hypersensitivity to moving or conflicting visual stimulation is named visual dependence. (2) Methods: Visuo-vestibular interactions were analyzed via the functional Head Impulse Test (fHIT) with and without optokinetic stimulation (o-fHIT) in 25 patients with VM, in 20 subjects affected by AUV, and in 20 healthy subjects. We calculated the percentage of correct answers (%CA) without and with the addition of the optokinetic background (OB). (3) In VM groups, the %CA on the fHIT was 92.07% without OB and 73.66% with OB. A significant difference was found between %CA on the deficit side and that on the normal side in AUV, both without OB and with OB. (4) Conclusions: The fHIT results in terms of %CA with and without OB could be useful to identify the presence of a dynamic visual dependence, especially in patients suffering from VM. The difference in %CA with and without OB could provide instrumental support to help correctly identify subjects suffering from VM. We propose the use of the fHIT in clinical practice whenever there is a need to highlight a condition of dynamic visual dependence.


2021 ◽  
Author(s):  
Richard Tolulope Ibitoye ◽  
Emma-Jane Mallas ◽  
Niall J Bourke ◽  
Diego Kaski ◽  
Adolfo Miguel Bronstein ◽  
...  

Area OP2 in the posterior peri-sylvian cortex has been proposed to be the core human vestibular cortex. We defined the functional anatomy of OP2 using spatially constrained independent component analysis of functional MRI data from the Human Connectome Project. Ten distinct subregions were identified. Most subregions showed significant connectivity to other areas with vestibular function: the parietal opercula, the primary somatosensory cortex, the supracalcarine cortex, the left inferior parietal lobule and the anterior cingulate cortex. OP2 responses to vestibular and visual-motion were analysed in 17 controls and 17 right-sided unilateral vestibular lesion patients (vestibular neuritis) who had previously undergone caloric and optokinetic stimulation during functional MRI. In controls, a posterior part of right OP2 showed: (a) direction-selective responses to visual motion; and (b) activation during caloric stimulation that correlated positively with perceived self-motion, and negatively with visual dependence. Patients showed abnormal OP2 activity, with an absence of visual or caloric activation of the healthy ear and no correlations with dizziness or visual dependence despite normal brainstem responses to caloric stimulation (slow-phase nystagmus velocity). A lateral part of right OP2 showed activity that correlated with chronic dizziness (situational vertigo) in patients. Our results define the functional anatomy of OP2 in health and disease. A posterior subregion of right OP2 shows strong functional connectivity to other vestibular regions and a visuo-vestibular profile that becomes profoundly disrupted after vestibular disease. In vestibular patients, a lateral subregion of right OP2 shows responses linked to the challenging long-term symptoms which define poorer clinical outcomes.


Healthcare ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 723
Author(s):  
Nina Smyth ◽  
Monica Milani ◽  
Lisa Thorn ◽  
Maria Flynn ◽  
John F. Golding ◽  
...  

There are known links between the hypothalamic–pituitary–adrenal (HPA) axis and systems responsible for regulating posture. Our aim was to explore directly, for the first time, whether an aspect of circadian HPA axis activity (the cortisol awakening response: CAR) was associated with greater visual dependency in postural control. For measurement of the CAR, electronically monitored saliva samples were collected by participants following morning awakening in their home environment. On the afternoons of the same days, postural sway was measured in the laboratory by exposing participants to static (control) and moving visual stimuli whilst standing still and upright on a force platform. Visual dependence was assessed as the increase in postural sway (path length) during exposure to the moving compared with the static condition. The 44 measurement days were derived from four days for each of eleven healthy participants (mean ± SD age: 51.18 ± 3.3 years). As expected, postural sway was greater when exposed to moving versus static cues. Mixed regression modelling showed that participants with smaller four day average CARs had greater deterioration in postural sway when presented with moving stimuli. These data are the first to document associations between the CAR and visual dependency in postural sway.


2021 ◽  
Vol 13 ◽  
Author(s):  
Milda Totilienė ◽  
Virgilijus Uloza ◽  
Vita Lesauskaitė ◽  
Gytė Damulevičienė ◽  
Rima Kregždytė ◽  
...  

Aging affects the vestibular system and may disturb the perception of verticality and lead to increased visual dependence (VD). Studies have identified that abnormal upright perception influences the risk of falling. The aim of our study was to evaluate subjective visual vertical (SVV) and VD using a mobile virtual reality-based system for SVV assessment (VIRVEST) in older adults with falls and evaluate its relationship with clinical balance assessment tools, dizziness, mental state, and depression level. This study included 37 adults >65 years who experienced falls and 40 non-faller age-matched controls. Three tests were performed using the VIRVEST system: a static SVV, dynamic SVV with clockwise and counter-clockwise background stimulus motion. VD was calculated as the mean of absolute values of the rod tilt from each trial of dynamic SVV minus the mean static SVV rod tilt. Older adults who experienced falls manifested significantly larger biases in static SVV (p = 0.012), dynamic SVV (p < 0.001), and VD (p = 0.014) than controls. The increase in static SVV (odds ratio = 1.365, p = 0.023), dynamic SVV (odds ratio = 1.623, p < 0.001) and VD (odds ratio = 1.460, p = 0.010) tilt by one degree significantly related to falls risk in the faller group. Fallers who had a high risk of falling according to the Tinetti test exhibited significantly higher tilts of dynamic SVV than those who had a low or medium risk (p = 0.037). In the faller group, the increase of the dynamic SVV tilt by one degree was significantly related to falls risk according to the Tinetti test (odds ratio = 1.356, p = 0.049). SVV errors, particularly with the dynamic SVV test (i.e., greater VD) were associated with an increased risk of falling in the faller group. The VIRVEST system may be applicable in clinical settings for SVV testing and predicting falls in older adults.


2021 ◽  
Author(s):  
Augusto-Pietro Casani ◽  
Francesco Lazzerini ◽  
Nicola Ducci ◽  
Ottavia Marconi ◽  
Nicola Vernassa

Abstract Visually induced vertigo (i.e., vertigo provoked by moving visual scenes) could be considered as a noticeable feature of Vestibular Migraine (VM) and could be present in patients suffering from Acute Unilateral Vestibulophaty (AUV). The hypersensitivity to moving or conflicting visual stimulations is named Visual Dependence. The visuo-vestibular interactions were analyzed using functional Head Impulse Test (fHIT) with and without optokinetic stimulation (o-fHIT) in 25 patients with VM and 20 subjects affected by AUV. We calculated the percentage of correct answer (%CA) without and with the addition of confounding screen (CS). In VM groups the %CA at fHIT was 92,07% without CS and 73,66% with CS. A significant difference has been found between %CA on the deficit side and the normal side in AUV, both without CS and with CS). The results of fHIT in term of %CA with and without CS could be very useful to identify the presence of visual dependence especially in patients suffering from VM. The difference of %CA with and without CS could provide an instrumental support to correctly identify patients with VM. We propose the use of fHIT in clinical practice whenever there is a need to highlight a condition of visual dependence.


2021 ◽  
pp. 1-8
Author(s):  
Doaa S. Al-Sharif ◽  
Pamela Roehm ◽  
T. Logan Lindemann ◽  
Levent Dumenci ◽  
Emily A. Keshner

BACKGROUND: Dizziness affects 20–30%of the general population. A subgroup of dizzy patients with chronic migraine suffers vertigo implying that the migraine has a vestibular component. Vestibular migraine remains a diagnosis of exclusion based on history. OBJECTIVE: A link between headaches and dizziness suggests that these individuals would demonstrate dizziness and instability in complex, dynamic visual environments as a result of an inability to correctly process conflicting visual and vestibular signals. METHODS: A convenience sample of 74 patients (22 men and 52 women; average age 56.2 years) who presented with complaints of dizziness participated. Effects of Visual-Vestibular Mismatch (VVM) were measured using a modified VVM questionnaire. Visual dependence was measured as the error to subjective visual vertical using a computerized Rod and Frame test. RESULTS: Forty-two participants (56.8%) tested positive for VVM. Of these, 68.9%were patients with concomitant complaints of headaches. Visual dependence was present in 41.5%of all patients but showed no significant correlation with headache. 22.2%of patients had visual dependence and complained of headaches. CONCLUSIONS: These results demonstrate that sensory reweighting occurs in patients experiencing dizziness and headache, supports the role of vestibular involvement in this disorder, and provides future direction for novel interventions.


Author(s):  
Giovanni Bertolini ◽  
Fausto Romano ◽  
Dominik Straumann ◽  
Katharine Keller ◽  
Antonella Palla ◽  
...  

AbstractConcussed patients with chronic symptoms commonly report dizziness during exposure to environments with complex visual stimuli (e.g. supermarket aisles, busy crossroads). Such visual induced dizziness is well-known in patients with vestibular deficits, in whom it indicates an overreliance on visual cues in sensory integration. Considering that optokinetic after-nystagmus (OKAN) reflects the response of the central network integrating visual and vestibular self-motion signals (velocity storage network), we investigated OKAN in 71 patients [17 (23.9%) females, 30.36 ± 9.05 years old] who suffered from persistent symptoms after a concussion and presented clinical signs suggesting visual dependence. Data were retrospectively compared with 21 healthy individuals [13 (61.9%) females, 26.29 ± 10.00 years old]. The median values of the slow cumulative eye position and of the time constant of OKAN were significantly higher in patients than in healthy individuals (slow cumulative eye position: 124.15 ± 55.61° in patients and 77.87 ± 45.63° in healthy individuals—p = 0.012; time constant: 25.17 ± 10.27 s in patients and 13.95 ± 4.92 s in healthy individuals—p = 0.003). The receiving operating curve (ROC) estimated on the time constant had an overall area under the curve of 0.73. Analysis of the ROC suggests that a test measuring the OKAN time constant could obtain a sensitivity of 0.73 and specificity of 0.72 in determining the origin of the visual-related disturbances in those patients (threshold 16.6 s). In a subset of 43 patients who also performed the Sensory Organization Test (SOT), the proposed OKAN test was twice as sensitive as the SOT. This study suggests that concussed patients with persisting visual symptoms may have an underlying impairment of the velocity storage mechanism and that measuring the OKAN time constant can objectify such impairment.


2020 ◽  
Vol 41 (3) ◽  
pp. 323-336 ◽  
Author(s):  
Mario R. Ruiz-Monachesi ◽  
Soledad Valdecantos ◽  
Félix B. Cruz

Abstract Animals employ a wide variety of communication tactics that rely on distinct sensory modalities. Lizards are characterized by their heightened dependence on chemical and visual communication. Some authors have proposed that a reduced number of chemical secretory pores may be associated with an increased visual dependence in some species. Here, we study two species of Liolaemus lizards with different chemical features to compare their visual and chemical communication. The first species, L. coeruleus, does not have precloacal pores in either sex, while L. albiceps has precloacal pores in both sexes. We expect that L. coeruleus will principally adhere to the visual modality, while L. albiceps will show greater chemical responses. We filmed the lizard’s response to different chemical and visual stimuli. In the trials, both species demonstrated chemical self-recognition, L. albiceps exhibited less total time in motion but more behavioural displays in the presence of conspecific scents, suggesting conspecific chemical recognition too. On the other hand, visuals results showed that L. coeruleus reacted more to the presence of conspecifics than L. albiceps. These observations suggest that L. coeruleus relies more on visual signalization, while L. albiceps has a greater dependence on chemical communication. Our results may indicate a correspondence between precloacal secretions and the response to these by conspecifics in both species studied.


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