Idiosyncratic viewing patterns of social scenes reflect individual preferences

In general, humans preferentially look at conspecifics in naturalistic images. However, such group-based effects might conceal systematic individual differences concerning the preference for social information. Here, we investigated to what degree fixations on social features occur consistently within observers and whether this preference generalizes to other measures of social prioritization in the laboratory as well as the real world. Participants carried out a free viewing task, a relevance taps task that required them to actively select image regions that are crucial for understanding a given scene, and they were asked to freely take photographs outside the laboratory that were later classified regarding their social content. We observed stable individual differences in the fixation and active selection of human heads and faces that were correlated across tasks and partly predicted the social content of self-taken photographs. Such relationship was not observed for human bodies indicating that different social elements need to be dissociated. These findings suggest that idiosyncrasies in the visual exploration and interpretation of social features exist and predict real-world behavior. Future studies should further characterize these preferences and elucidate how they shape perception and interpretation of social contexts in healthy participants and patients with mental disorders that affect social functioning.

Rehabilitation to Improve Gaze and Postural Stability in People With Multiple Sclerosis: A Randomized Clinical Trial

BACKGROUND

People with multiple sclerosis (PwMS) frequently experience dizziness and imbalance that may be caused by central vestibular system dysfunction. Vestibular rehabilitation may offer an approach for improving dysfunction in these people.

OBJECTIVE

To test the efficacy of a gaze and postural stability (GPS) retraining intervention compared to a strength and endurance (SAE) intervention in PwMS.

METHODS

About 41 PwMS, with complaints of dizziness or history of falls, were randomized to either the GPS or SAE groups. Following randomization participants completed 6-weeks of 3×/week progressive training, delivered one-on-one by a provider. Following intervention, testing was performed at the primary (6-weeks) and secondary time point (10-weeks). A restricted maximum likelihood estimation mixed effects model was used to examine changes in the primary outcome of the Dizziness Handicap Inventory (DHI) between the 2 groups at the primary and secondary time point. Similar models were used to explore secondary outcomes between groups at both timepoints.

RESULTS

Thirty-five people completed the study (17 GPS; 18 SAE). The change in the DHI at the primary time point was not statistically different between the GPS and SAE groups (mean difference = 2.33 [95% CI -9.18, 12.85]). However, both groups demonstrated significant improvement from baseline to 6-weeks (GPS -8.73; SAE -7.31). Similar results were observed for secondary outcomes and at the secondary timepoint.

CONCLUSIONS

In this sample of PwMS with complaints of dizziness or imbalance, 6-weeks of GPS training did not result in significantly greater improvements in dizziness handicap or balance compared to 6-weeks of SAE training.

Assessment of Saccades and Gaze Stability in the Diagnosis of Pediatric Concussion

OBJECTIVE

To evaluate the discriminatory ability of different repetition increments of saccades and gaze stability testing for diagnosing concussion in adolescents.

DESIGN

Cross-sectional.

SETTING

Suburban high school and academic pediatric tertiary care center.

PARTICIPANTS

Sixty-nine adolescent athletes within 28 days of a sports- or recreation-related concussion and 69 adolescent athletes without recent concussion.

ASSESSMENT OF INDEPENDENT VARIABLES

Symptom provocation with horizontal and vertical saccades and gaze stability testing performed up to 30 repetitions.

MAIN OUTCOME MEASURES

Sensitivity and specificity at 10-repetition increments (≤10, ≤20, ≤30) and area under the receiver operating characteristic curves (AUC) of a visio-vestibular examination (VVE) subscore, scored 0 to 4 based on the number of assessments with symptom provocation, at each repetition increment.

RESULTS

Sensitivity improved when increasing from ≤10 to ≤20 to ≤30 repetitions for horizontal (25% to 50% to 69%) and vertical (32% to 52% to 74%) saccades and horizontal (19% to 45% to 71%) and vertical (23% to 45% to 72%) gaze stability. Specificity was comparable at ≤10 and ≤20 repetitions, but decreased at ≤30 repetitions across assessments. For a VVE subscore (0-4) based on the number of symptomatic assessments, the discriminatory ability of the test was highest at ≤20 repetitions (AUC of 0.79) with an optimal subscore of one (sensitivity 59%, specificity 96%).

CONCLUSIONS

A VVE including a higher threshold level of repetitions for saccades and gaze stability has improved discriminatory ability for concussion, with an optimized AUC of 0.79 at ≤20 repetitions.

CLINICAL RELEVANCE

The findings in this study suggest that a higher threshold level of repetitions of 2 commonly used visio-vestibular assessments enables clinicians to more accurately diagnose youth concussion.

Evaluation of Fixational Behavior throughout Life

Background: To quantify development of gaze stability throughout life during short and long fixational tasks using eye tracking technology. Methods: Two hundred and fifty-nine participants aged between 5 months and 77 years were recruited along the study. All participants underwent a complete ophthalmological assessment. Fixational behavior during long and short fixational tasks was analyzed using a DIVE (Device for an Integral Visual Examination), a digital test assisted with eye tracking technology. The participants were divided into ten groups according to their age. Group 1, 0–2 years; group 2, 2–5 years; group 3, 5–10 years; group 4, 10–20 years; group 5, 20–30 years; group 6, 30–40 years; group 7, 40–50 years; group 8, 50–60 years; group 9, 60–70 years; and group 10, over 70 years. Results: Gaze stability, assessed by logBCEA (log-transformed bivariate contour ellipse area), improved with age from 5 months to 30 years (1.27 vs. 0.57 deg² for long fixational task, 0.73 vs. −0.04 deg² for short fixational task), while fixations tend to be longer (1.95 vs. 2.80 msec for long fixational tasks and 0.80 vs. 1.71 msec for short fixational tasks). All fixational outcomes worsened progressively from the fifth decade of life. Log-transformed bivariate contour ellipse area (0.79, 0.83, 0.91, 1.42 deg² for long fixational task and 0.01, 0.18, 0.28, 0.44 deg² for short fixational task, for group 7, 8, 9, and 10 respectively). Stimuli features may influence oculomotor performance, with smaller stimuli providing prolonged fixations. Conclusions: Fixational behavior can be accurately assessed from 5 months of age using a DIVE. We report normative data of gaze stability and duration of fixations for every age group. Currently available technology may increase the accuracy of our visual assessments at any age.

Report of oscillopsia in ataxia patients correlates with activity, not vestibular ocular reflex gain

BACKGROUND

Patients with cerebellar ataxia report oscillopsia, "bouncy vision" during activity, yet little is known how this impacts daily function. The purpose of this study was to quantify the magnitude of oscillopsia and investigate its relation to vestibulo-ocular reflex (VOR) function and daily activity in cerebellar ataxia.

METHODS

19 patients diagnosed with cerebellar ataxia and reports of oscillopsia with activity were examined using the video head impulse test (vHIT), Oscillopsia Functional Index (OFI), and clinical gait measures. Video head impulse data was compared against 40 healthy controls.

RESULTS

OFI scores in ataxia patients were severe and inversely correlated with gait velocity (r = -0.55, p <  0.05), but did not correlate with VOR gains. The mean VOR gain in the ataxic patients was significantly reduced and more varied compared with healthy controls. All patients had abnormal VOR gains and eye/head movement patterns in at least one semicircular canal during VHIT with passive head rotation.

CONCLUSIONS

Patients with cerebellar ataxia and oscillopsia have impaired VOR gains, yet severity of oscillopsia and VOR gains are not correlated. Patients with cerebellar ataxia have abnormal oculomotor behavior during passive head rotation that is correlated with gait velocity, but not magnitude of oscillopsia.

Suppression of motion vision during course-changing, but not course-stabilizing, navigational turns

From mammals to insects, locomotion has been shown to strongly modulate visual-system physiology. Does the manner in which a locomotor act is initiated change the modulation observed? We performed patch-clamp recordings from motion-sensitive visual neurons in tethered, flying Drosophila. We observed motor-related signals in flies performing flight turns in rapid response to looming discs and also during spontaneous turns, but motor-related signals were weak or non-existent in the context of turns made in response to brief pulses of unidirectional visual motion (i.e., optomotor responses). Thus, the act of a locomotor turn is variably associated with modulation of visual processing. These results can be understood via the following principle: suppress visual responses during course-changing, but not course-stabilizing, navigational turns. This principle is likely to apply broadly-even to mammals-whenever visual cells whose activity helps to stabilize a locomotor trajectory or the visual gaze angle are targeted for motor modulation.

The Gaze Stabilization Test Following Concussion

BACKGROUND

Concussion can cause vestibular dysfunction and oculomotor abnormalities which can lead to dizziness and protracted recovery time. There are few clinically useful, functional measures of the vestibulo-ocular reflex (VOR) post-concussion.

PURPOSE

The purpose of this study was to examine the gaze stabilization test (GST) in those referred for vestibular physical therapy following concussion, to determine the association between GST and other measures of recovery following concussion, and to examine the effect of demographic variables on GST performance.

RESEARCH DESIGN

Retrospective chart review.

STUDY SAMPLE

One hundred fifty-eight individuals who sustained a concussion and were referred to vestibular physical therapy.

DATA COLLECTION AND ANALYSIS

Horizontal and vertical GST scores (HGST and VGST), neurocognitive testing results, and demographic data were extracted retrospectively from the patient health record. Correlations between GST velocity and neurocognitive test results and between GST and patient-reported outcomes were examined. Differences in GST performance among patient subgroups were examined using one-way analysis of variance.

RESULTS

Subjects included individuals aged 12 to 43 years (mean = 20, standard deviation [SD] = 7), with most having sport-related concussion (67%). The mean time from injury to GST was 215 days (SD = 241) and the mean time from physical therapy evaluation to GST was 48 days (SD = 54). HGST and VGST had a weak positive correlation to the Activities-Specific Balance Confidence Scale (r = 0.20, r = 0.21) and weak negative correlation to the Dizziness Handicap Inventory (r = -0.18, r = -0.22). HGST had a weak positive correlation to the visual motor processing speed domain of the immediate post-concussion assessment and cognitive test (r = 0.20). Male patients achieved significantly higher velocities than female patients on HGST and VGST (p = 0.02, p = 0.01).

CONCLUSIONS

The present study details the use of GST in patients with concussion and demonstrates an association with common outcome measures in vestibular rehabilitation. Results indicate that patients who achieved higher velocities on GST perceived lower handicap due to dizziness and had higher confidence in their balance. GST may be a relevant test of VOR in this population, as it is a more functional test of the VOR required for sports. Future work is needed to further evaluate the role of GST in concussion management.

Eye Movements Are Correctly Timed During Walking Despite Bilateral Vestibular Hypofunction

Individuals with bilateral vestibular hypofunction (BVH) often report symptoms of oscillopsia (the perception that the world is bouncing or unstable) during walking. Efference copy/proprioception contributes to locomotion gaze stability in animals, sometimes inhibiting the vestibulo-ocular reflex (VOR). Gaze stability requires both adequate eye velocity and appropriate timing of eye movements. It is unknown whether eye velocity (VOR gain), timing (phase), or both are impaired for individuals with BVH during walking. Identifying the specific mechanism of impaired gaze stability can better inform rehabilitation options. Gaze stability was measured for eight individuals with severe BVH and eight healthy age- and gender-matched controls while performing a gaze fixation task during treadmill walking. Frequency response functions (FRF) were calculated from pitch eye and head velocity. A one-way ANOVA was conducted to determine group differences for each frequency bin of the FRF. Pearson correlation coefficients were calculated to determine the relationship between the real and imaginary parts of the FRF and the Oscillopsia Visual Analog Scale (oVAS) scores. Individuals with BVH demonstrated significantly lower gains than healthy controls above 0.5 Hz, but their phase was ideally compensatory for frequencies below 3 Hz. Higher oVAS scores were correlated with lower gain. Individuals with BVH demonstrated ideal timing for vertical eye movements while walking despite slower than ideal eye velocity when compared to healthy controls. Rehabilitation interventions focusing on enhancing VOR gain during walking should be developed to take advantage of the intact timing reported here. Specifically, training VOR gain while walking may reduce oscillopsia severity and improve quality of life.

Normative Scores for the NIH Toolbox Dynamic Visual Acuity Test from 3 to 85 Years

As part of the National Institutes of Health Toolbox initiative, a computerized test of dynamic visual acuity (cDVA) was developed and validated as an easy-to-administer, cost- and time-efficient test of vestibular and visual function. To establish normative reference values, 3,992 individuals, aged 3–85 years, without vestibular pathology underwent cDVA testing at multiple clinical research testing facilities across the United States. Test scores were stratified by sociodemographic characteristics. cDVA was worse in males (p < 0.001) and those subjects 50 years or older, while there was no difference in dynamic visual acuity across age groups binned from 3 to 49 years. Furthermore, we used these normative cDVA data as a criterion reference to compare both the long (validated) and short versions of the test. Both versions can distinguish between those with and without vestibular pathology (p = 0.0002 long; p = 0.0025 short). The intraclass correlation coefficient between long- and short-cDVA tests was 0.86.

Vestibular rehabilitation therapy: review of indications, mechanisms, and key exercises

Vestibular rehabilitation therapy (VRT) is an exercise-based treatment program designed to promote vestibular adaptation and substitution. The goals of VRT are 1) to enhance gaze stability, 2) to enhance postural stability, 3) to improve vertigo, and 4) to improve activities of daily living. VRT facilitates vestibular recovery mechanisms: vestibular adaptation, substitution by the other eye-movement systems, substitution by vision, somatosensory cues, other postural strategies, and habituation. The key exercises for VRT are head-eye movements with various body postures and activities, and maintaining balance with a reduced support base with various orientations of the head and trunk, while performing various upper-extremity tasks, repeating the movements provoking vertigo, and exposing patients gradually to various sensory and motor environments. VRT is indicated for any stable but poorly compensated vestibular lesion, regardless of the patient's age, the cause, and symptom duration and intensity. Vestibular suppressants, visual and somatosensory deprivation, immobilization, old age, concurrent central lesions, and long recovery from symptoms, but there is no difference in the final outcome. As long as exercises are performed several times every day, even brief periods of exercise are sufficient to facilitate vestibular recovery. Here the authors review the mechanisms and the key exercises for each of the VRT goals.