Choosing sides: lateralization in line trisection and quadrisection as a function of reading direction and handedness

It might be intuited that a person's reading direction will impact linguistic and/or oculomotor tasks. Whether it also influences nonlanguage tasks, and by what means, is less clear. A novel technique to probe this effect is introduced in this paper, and the affirmative results are presented. The line bisection task has been a standard bedside diagnostic technique for assessing hemifield spatial neglect for many years. In recent years, numerous studies have also examined how normal subjects perform on this task. A recent line of study has focused on the reading habits of the subjects and the effect it has on line bisection. Most European languages are read from left to right, and it is thus postulated that readers of those languages will scan a line from left to right. On the other hand, Hebrew is read from right to left. These previous studies have yielded intriguing results about the role that reading direction plays in nonlanguage tasks. The present study utilized two other line partition tasks, line trisection and line quadrisection, and subjects whose principal reading language was either right-to-left or left-to-right. These tasks are ambiguous when used without instructing the subject on which side to perform the line transection. It was found that principal language was correlated with the side on which the subject chose to trisect or quadrisect the line. However, there was no correlation between preferred side and writing hand and there was no significant difference in accuracy between the preferred side and the secondary side. Thus, the preferred side in this nonlanguage task does not seem to be influenced by writing hand or accuracy but rather would seem to depend exclusively upon the earliest legitimate point, as determined by reading direction.     

Visual assessment in children with cerebral palsy: implementation of a functional questionnaire

Aim The aim of this study was to evaluate an interdisciplinary visual assessment for multiply challenged children diagnosed with cerebral palsy (CP). Method A comprehensive ophthalmological assessment together with a visual classification scale (VCS) and a questionnaire evaluating daily visual function were completed regarding 77 children (41 females, 36 males; age range 3–20y; mean age 8y 3mo [SD 4y 3mo]; Gross Motor Function Classification System [GMFCS] level V; Manual Ability Classification System level V) who were diagnosed with CP (79.2% spastic quadriplegia, 6.5% athetoid quadriplegia, 10.4% mixed type, 3.9% hemiplegia). All participants had severe to profound motor and intellectual disability and an inability to communicate consistently through either verbal or assisted communication. The interrater and test–retest reliability of the questionnaire and its validity in comparison with the VCS were examined. In addition, the contribution of ophthalmological testing in predicting daily visual function was assessed. Results The ophthalmological examination revealed three diagnostic subgroups: a group with cerebral visual impairment (CVI), a group with optic atrophy, and a group without visual impairment. The questionnaire was found to have high values of interrater reliability (interclass correlation coefficient [ICC]=0.873; 95% confidence interval [CI] 0.762–0.935) and test–retest reliability (ICC=0.988; 95% CI 0.964–0.996). Validity was established for the questionnaire factors: task‐orientated visual function (r=0.802; 95% CI 0.669–0.885) and basic visual skills (r=0.691; 95% CI 0.504–0.816). The questionnaire provided information about daily visual performance not available from one‐time ophthalmological testing, particularly for participants diagnosed with CVI. The visual performance scale significantly predicted daily visual function for all groups. Interpretation This study highlights the benefits of implementing a diagnostic performance scale as well as a reliable functional questionnaire to achieve a precise visual assessment of children with severe neurological impairment.     

Bisections in two languages: when number processing, spatial representation, and habitual reading direction interact

Calabria and Rossetti (2005) demonstrated that spatial biases related to the mental number line can be seen even when bisecting strings of number words. Strings of smaller magnitude number words were bisected further to the left than strings of larger magnitude number words.The current study investigated whether the left-to-right mental number line associated with number processing will result in similar spatial biases despite a habitual, right-to-left reading direction. Monolingual left-to-right readers were compared to bidirectional readers of English and Hebrew. Strings of Arabic numerals and of number words (e.g., THREE, EIGHT) were presented in separate conditions of English and Hebrew. Significant rightward biases were seen among native Hebrew readers, regardless of English reading level; whereas native English readers (both bidirectional and monodirectional) did not show significant biases to either the left or the right. The spatial bias in bisecting either Arabic numeral strings or number words was related to the habitual reading direction of the participant. There was no difference in spatial bias or for frequency of spatial bias based on numerical magnitude for either condition. We discuss the influence of cultural factors, such as reading direction and proficiency, on the representation of spatial and numerical material.     

Dynamic properties of horizontal and vertical eye movements in parkinsonian syndromes

We studied dynamic properties of horizontal, vertical, and oblique eye movements in 23 patients with the following parkinsonian syndromes: idiopathie parkinsonism (PD), multiple system atrophy (MSA), pure akinesia (PA), progressive supranuclear palsy (PSP), and cortical-basal ganglionic degeneration (CBGD). Compared with age-matched controls, only PSP patients showed slowing of saccades. Patients in all groups showed saccadic hypometria that was most marked vertically. The trajectories of saccades made to diagonal target jumps were deviated toward the horizonal plane, due to the vertical hypometria; this was most marked in PA and PSP groups. Saccade latency was only increased in the CBGD group. Sinusoidai smooth pursuit did not differentiate between controls and patients; however, with step-ramp stimuli, pursuit eye acceleration was impaired in all patient groups compared with controls. The vestibulo-ocular reflex, with or without visual enhancement, was similar in patients and controls. These findings indicate that (1) in parkinsonian syndromes apart from PSP, the saccade-generating brainstem burst neurons are probably spared, but the signals that they receive, specifying the size and direction of saccades, are flawed; and (2) measurements of the gain and trajectory of oblique saccades, and initiation of smooth pursuit, may aid in diagnosing these different types of parkinsonism.     

Comprehensive computerized assessment of cognitive sequelae of a complete 12-16 hour fast

Food deprivation has been shown to deleteriously affect human cognition, but findings are equivocal, and few studies have examined several cognitive domains. In this study, the authors used computerized testing to describe the profile of shifts in cognition attributable to short-term religious fasting. Multiple cognitive domains were evaluated at midday and late afternoon following complete abstention from eating and drinking beginning at midnight. Cross-domain, fasting-related deficits were found for tasks requiring perception of spatial relations. Fasting-related information processing deficits were found for response time but not accuracy for test levels of intermediate difficulty. Time-of-day effects often reflected poorer afternoon performance. These findings provide a detailed profile of cognitive consequences of food deprivation, affected by time of day, task demands, and type of outcome.     

The Duncker illusion: intersubject variability, brief exposure, and the role of eye movements in its generation

PURPOSE: The Duncker illusion, also known as induced motion, is the illusory component of an object's motion that results from background movement. The origins of this robust phenomenon are still subject to debate. The goal of this study was to examine the role eye movements play in its generation. METHODS: The Duncker illusion was generated by rear-projecting an LED target and a random-dot background onto a semitranslucent screen. Each moved under independent control of mirror galvanometers. The background was either stationary or moved vertically, whereas the target moved horizontally with various degrees of a vertical component. Using a two-alternative, forced-choice cancellation paradigm involving multiple interleaved staircases, seven human subjects quantified the illusion under a variety of conditions. These conditions included varying the exposure time from 50 to 200 ms. RESULTS: The strength of the illusion did not decrease, even when exposures too brief to generate eye movement were used. Four of the subjects showed no difference between long and short exposures (P > 0.12). In two the illusion was stronger for short exposures (P < 0.05), and in one the illusion was not quantifiable. There was little intrasubject variability across trial types, yet there was a large intersubject variability in the strength of the illusion. CONCLUSIONS: The illusion is robust in that it is perceived under a wide variety of conditions by all observers. By varying the parameters, it was possible to demonstrate that eye movements do not play a role in generating the illusion and that this robust illusion is most likely caused by the visual system attributing relative motion between target and background to target motion and ignoring any true background movement. The mechanism by which this occurs varies in degree between individuals.     

Seeing the forest without losing sight of the trees: details are processed despite reversal insensitivity in structure from motion

Presenting a subject with two random-dot flow fields produces a persuasive 3D percept of a rotating cylinder whose perceived direction of rotation is bi-stable and reverses spontaneously. When real reversals are introduced subjects rarely perceive them. It is possible that although these reversals are consciously ignored, they are registered and available to the visual system for potential later use. We tested this prediction by comparing the number of spontaneously perceived reversals with and without real reversals. We found that although the actual reversals were usually not perceived, they nonetheless increased the number of spontaneous flips. The visual system apparently prefers to retain global structure rather than perceive a motion change of every element in the stimulus. However, it does not completely ignore the changes and incorporates them into other emerging interpretations. These findings argue against the fatigue hypothesis of spontaneous reversals which would predict a decrease in the number of reversals and can be interpreted as supporting the information-processing view by noting that due to the real reversals, the visual system continues to accrue data that argues against the current representation and facilitates switching to the rival representation.     

Confronting the bomber: coping at the site of previous terror attacks

Terror exposure has become commonplace in Israel, with civilians needing to develop appropriate coping mechanisms. This study investigated coping mechanisms of those who are able to return to leisure activity at sites of previous terror attacks. A specially designed questionnaire, exploring knowledge of the terror event, previous terror exposure, coping mechanisms, state of anxiety, and mood, was administered to 93 restaurant attendees at sites of well-known recent terror attacks (2001-2005). Most respondents were aware of the previous terror attack (92.3%) and most reported no fear at revisiting (70.3%), with 20.9% reporting some anxiety and 5.5% reporting moderate or severe anxiety. Sixty percent reported that they have no fear that a terror attack will reoccur at the same place. Some (27.7%) reported change in practices or decrease in one or more activity, especially use of public transport (18%). The most helpful reported resource for facilitating stress coping following a suicide bombing was to "call or be in touch with friends or relatives," and least helpful was "medicines." Over half of respondents (53%) reported that the current security climate affected their mood. Older individuals and females were more affected by terror events. Study observations confirm that resilience develops in the general population in response to ongoing terror attacks. Response to terror is heterogeneous with a range of coping mechanisms expressed.     

Restless legs syndrome as side effect of second generation antidepressants

Although of clinical interest, the question is still not fully answered whether antidepressants (AD) can cause or exacerbate restless legs syndrome (RLS). The literature provides contradictory information. This study addresses this problem for the class of second generation AD.In four neurological offices, all patients treated for the first time with an AD were prospectively observed with regard to the question of whether RLS occurred or pre-existing RLS worsened as a result of the medication. Because initial treatment in the participating offices is mainly executed with “modern” selective AD, the study was restricted to these drugs (fluoxetine, paroxetine, citalopram, sertraline, escitalopram, venlafaxine, duloxetine, reboxetine, and mirtazapine).In 9% of patients, RLS was recorded as a side effect related to the administration of AD. The frequency of this side effect varied among the drugs. The problem is most pronounced with mirtazapine provoking or deteriorating RLS in 28% of patients. By contrast, no case occurred during use of reboxetine. As for the other AD, the rate of newly occurred and deteriorated RLS, ranged from 5% to 10%. Typically, RLS occurred during the initial days of treatment.