Rod and frame alignment times increase when the frame is tilted.

The Rod and Frame test measures an individual’s subjective assessment of visual vertical and horizontal in the presence of a surrounding tilted frame. Attention has focused upon the effects of the surrounding frame upon spatial accuracy (Spatial Frame Effect). We have investigated if the tilted frame also affects the time that subjects take to make the alignment (Temporal Frame Effect). Results: 125 subjects performed a computerised Rod and Frame test to investigate the effects of a tilted frame on subjective visual vertical and horizontal. In addition the program recorded the time taken to make each alignment. For most subjects the mean Spatial Frame Effect was small (vertical 1.62, SD 0.93; horizontal 1.9, SD 1.43). The mean time taken to make alignments in the presence of a tilted frame was longer than when the frame was not tilted (vertical, +3.4s, SD 4.4; horizontal, +3.2s, SD 4.5). Differences in the times taken when the rod and frame were presented congruently and incongruently could be fully accounted for by the differences in steps needed to move the rod to its final alignment. No relationship was found between the spatial accuracy and the time to make the alignment and there was no relationship between the Spatial and Temporal Frame Effects. Conclusions: This study suggests that the Spatial, and Temporal, Frame Effects provide information about different aspects of the process of resolving conflicting visual information when making judgments on alignment. In everyday functions such as the maintenance of balance or susceptibility to motion sickness, the increased time taken may be as important as spatial accuracy

Young and Older Adults Differ in Integration of Sensory Cues for Vertical Perception.

Introduction: The subjective visual vertical (SVV) measures the perception of a person's spatial orientation relative to gravity. Weighted central integration of vestibular, visual, and proprioceptive inputs is essential for SVV perception. Without any visual references and minimal proprioceptive contribution, the static SVV reflects balance of the otolith organs. Normal aging is associated with bilateral and progressive decline in otolith organ function, but age-dependent effects on SVV are inconclusive. Studies on sensory reweighting for visual vertical and multisensory integration strategies reveal age-dependent differences, but most studies have included elderly participants in comparison to younger adults. The aim of this study was to compare young adults with older adults, an age group younger than the elderly. Methods: Thirty-three young and 28 older adults (50-65 years old) adjusted a tilted line accurately to their perceived vertical. The rod's final position from true vertical was recorded as tilt error in degrees. For otolithic balance, visual vertical was recorded in the dark without any visual references. The rod and frame task (RFT) with tilted disorienting visual frames was used for creating visuovestibular conflict. We adopted Nyborg's analysis method to derive the rod and frame effect (RFE) and trial-to-trial variability measures. Rod alignment times were also analyzed. Results: There was no age difference in signed tilts of SVV without visual reference. There was an age effect on RFE and on overall trial-to-trial variability of rod tilt, with older adults displaying larger frame effects and greater variability in rod tilts. Alignment times were longer in the tilted-frame conditions for both groups and in the older adults compared to their younger counterparts. The association between tilt accuracy and tilt precision was significant for older adults only during visuovestibular conflict, revealing an increase in RFE with an increase in tilt variability. Correlation of σSVV, which represents vestibular input precision, with RFE yielded exactly the same contribution of σSVV to the variance in RFE for both age groups. Conclusions: Older adults have balanced otolithic input in an upright position. Increased reliance on visual cues may begin at ages younger than what is considered elderly. Increased alignment times for older adults may create a broader time window for integration of relevant and irrelevant sensory information, thus enhancing their multisensory integration. In parallel with the elderly, older adults may differ from young adults in their integration of sensory cues for visual vertical perception

Inspiratory Conductance does not vary with Height, Weight, Body Mass Index, Age, Sex or Spirometric Volumes in Healthy Adults

Introduction and objective: We previously showed that inspiratory conductance (IC) can be calculated from early inspiratory pressure fall and initial acceleration of the inspiratory air column. To characterize IC further we conducted a study to determine whether its value varies with height, weight, BMI, age, sex and lung volumes. Methods: We measured IC, height, weight, FEV1, FVC and PEFR in 147 healthy volunteers’ age 18-50 years. Results: During tidal breathing at rest the mean (SD) IC was 8.31 (3.15) L s-1 kPa-1. No significant correlation was found between IC and height (r=0.04), weight (r=0.142), BMI (r=0.058), FEV1 (r=0.275), FVC (r=0.019), PEFR (r=0.182) or age (r=0.017) and there was no significant difference between men and women. The same was found for IC measured during slow deep breathing and rapid breathing. Conclusion: IC is independent of age, sex, height, weight, BMI and spirometric lung volumes so there is no imperative to correct for those factors in an individual. Within-subject directional changes in IC within the context of a short clinical timeframe might be the best potential for clinical application

Is spatial orientation affected by Ramadan fasting?

Purpose: Ramadan intermittent fasting (RIF) has produced heterogeneous and domain-specific effects on cognitive function. This study aims to investigate the effect of RIF on verticality perception or estimation of subjective visual vertical (SVV) in young adults. The significance of SVV is that it is essential for spatial orientation, upon which many daily activities depend. Methodology Verticality perception was assessed with a computerized rod and frame test (CRFT) in two visual conditions: without a surrounding frame and with a distracting tilted frame. The tilted frame condition measures level of visual dependence or reliance of visual cues for posture and orientation. In total, 39 young adult men were recruited at different stages of Ramadan fasting: 21 were tested at the end of the first week (Week 1) and 18 others at the end of the third week (Week 3) of Ramadan. Also, 39 participants were recruited to serve as a non-fasting control group. Factorial ANOVA analyses were conducted to identify the main effects of fasting status, time-of-day and the interaction between them on blood glucose levels, nocturnal sleep duration and vertical alignment errors. Findings The main effect of fasting status on glucose level was significant (p = 0.03). There was a significant time-of-day main effect on glucose levels (p = 0.007) and sleep duration (p = 0.004) only in fasting participants. Neither the main effects of fasting status nor time-of-day were significant for rod alignment errors in both visual conditions. The interaction of fasting status and time-of-day was not significant either. This may indicate that any negative effect of Ramadan fasting on activities that are critically dependent on verticality perception and spatial orientation, such as sports and driving, may not be due to verticality misperception. Originality The present study was the first to investigate the effect of Ramadan fasting on spatial orientation. It demonstrated robustness of verticality perception to fasting status and the point of fasting during Ramadan. Verticality perception was also unaffected by time-of-day effects in non-fasting and fasting groups at two different points of Ramadan. This study corroborates others reporting heterogeneous effects of Ramadan fasting on cognitive function

Perceptual visual dependence for spatial orientation in patients with schizophrenia

BACKGROUND: Patients with schizophrenia are reported to have vestibular dysfunction and to weigh vestibular input to a lesser extent compared to healthy controls. Such deficits may increase visual dependence (VD) for spatial orientation at a perceptual level in these patients. The aim of this study is to compare VD levels between healthy control and patients with schizophrenia and to explore associations between VD and clinical measures in these patients. Relation of VD to antipsychotic drug treatment is also discussed. METHOD: 18 patients with schizophrenia and 19 healthy controls participated in this study. The Rod and Disc Test (RDT) was used to create an optokinetic surround around a centrally located rod. Participants aligned the rod to their subjective visual vertical (SVV) in both static and dynamic disc conditions. VD was calculated as the difference in SVV between these two conditions. RESULTS: There was no group difference or gender difference in static or dynamic SVV as well as VD. There was no correlation between VD and any of the Positive and Negative Syndrome Scale (PANSS) scores, however VD was significantly correlated to illness duration in the patient group. CONCLUSIONS: Schizophrenia is not associated with greater VD levels at a perceptual level, compared to controls, indicating adequate visuo-vestibular integration for judging line verticality in these patients. Patients with greater chronicity of the disease are more visually dependent than those less chronically ill, consistent with previous reports of possible vestibular dysfunction in patients with schizophrenia. This may affect their daily functioning in dynamic visual environments

A human gene encoding morphine modulating peptides related to NPFF and FMRFamide

AbstractFMRFamide-related peptides have been isolated from both invertebrates and vertebrates and exhibit a wide range of biological effects in rats. We show here that in humans 2 FMRFamide-related peptides are encoded by a single gene expressed as a spliced mRNA. The larger predicted peptide (AGEGLNSQFWSLAAPQRFamide) differs from the peptide isolated from bovines (AGEGLSSPFWSLAAPQRFamide) by the substitutions of 2 amino acids. The shorter predicted peptide (NPSF, SQAFLFQPQRFamide) is 3 amino acids longer than the bovine 8 amino-acid NPFF (FLFQPQRFamide) or the human NPFF peptide isolated from serum [5], suggesting that the encoded protein is subject to cleavage by a tripeptidyl peptidase or by a novel processing mechanism. On rat spinal cord, the larger peptide is indistinguishable in activity from the equivalent bovine peptide whereas the smaller extended peptide is inactive

A comparison of two methods for estimating odds ratios: Results from the National Health Survey

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