Oblique saccades in internuclear ophthalmoplegia.

PURPOSE: Oblique saccades often display component stretching, in which the shorter vector in one cardinal direction is slowed so that its duration matches that of the longer vector in the orthogonal direction, resulting in a straighter trajectory. In internuclear ophthalmoplegia, adducting saccades are typically slowed while vertical saccades are unaffected. It is not known whether these slowed adducting movements are accompanied by adaptive component stretching of the vertical vector during oblique saccades. This was a cross-sectional study. We recorded the saccadic eye movement in 5 patients with right or bilateral internuclear ophthalmoplegia from multiple sclerosis and 17 healthy controls, using an EyeLink 1000 machine. The target stimulus was located at varying angles (0-360) and amplitudes (4, 8, 12 degrees). For each saccade we have calculated the curvature index as the main outcome measure, which is the area between the actual and ideal straight trajectory for oblique saccadic eye movements, divided by the square of the length of the straight trajectory, to give a unit-less metric for curvature. In the 17 control subjects, curvature showed a strong positive correlation between adducting saccades and the yoked abducting saccades of the other eye. In internuclear ophthalmoplegia, adducting saccades showed a strong curvature concave to the horizontal meridian, indicating inadequate component stretching, while abducting saccades did not differ from controls. This new sign of oblique saccadic curvature in internuclear ophthalmoplegia indicates a limitation of the range of central adaptive changes in response to distal lesions affecting transmission of the saccadic command.

Supporting Mental Health During the COVID-19 Pandemic Using a Digital Behavior Change Intervention: An Open-Label, Single-Arm, Pre-Post Intervention Study.

BACKGROUND: The COVID-19 pandemic is taking a toll on people's mental health, particularly as people are advised to adhere to social distancing, self-isolation measures, and government-imposed national lockdowns. Digital health technologies have an important role to play in keeping people connected and in supporting their mental health and well-being. Even before the COVID-19 pandemic, mental health and social services were already strained. OBJECTIVE: Our objective was to evaluate the 12-week outcomes of the digitally delivered Gro Health intervention, a holistic digital behavior change app designed for self-management of mental well-being, sleep, activity, and nutrition. METHODS: The study used a quasi-experimental research design consisting of an open-label, single-arm, pre-post intervention engagement using a convenience sample. Adults who had joined the Gro Health app (intervention) and had a complete baseline dataset (ie, 7-item Generalized Anxiety Disorder scale, Perceived Stress Scale, and 9-item Patient Health Questionnaire) were followed up at 12 weeks (n=273), including 33 (12.1%) app users who reported a positive COVID-19 diagnosis during the study period. User engagement with the Gro Health platform was tracked by measuring total minutes of app engagement. Paired t tests were used to compare pre-post intervention scores. Linear regression analysis was performed to assess the relationship between minutes of active engagement with the Gro Health app and changes in scores across the different mental health measures. RESULTS: Of the 347 study participants, 273 (78.67%) completed both the baseline and follow-up surveys. Changes in scores for anxiety, perceived stress, and depression were predicted by app engagement, with the strongest effect observed for changes in perceived stress score (F1,271=251.397; R2=0.479; P<.001). CONCLUSIONS: A digital behavior change platform that provides remote mental well-being support can be effective in managing depression, anxiety, and perceived stress during times of crisis such as the current COVID-19 pandemic. The outcomes of this study may also support the implementation of remote digital health apps supporting behavior change and providing support for low levels of mental health within the community.

The effects of task instructions on pro and antisaccade performance.

In the antisaccade task participants are required to overcome the strong tendency to saccade towards a sudden onset target, and instead make a saccade to the mirror image location. The task thus provides a powerful tool with which to study the cognitive processes underlying goal directed behaviour, and has become a widely used index of "disinhibition" in a range of clinical populations. Across two experiments we explored the role of top-down strategic influences on antisaccade performance by varying the instructions that participants received. Instructions to delay making a response resulted in a significant increase in correct antisaccade latencies and reduction in erroneous prosaccades towards the target. Instructions to make antisaccades as quickly as possible resulted in faster correct responses, whereas instructions to be as spatially accurate as possible increased correct antisaccade latencies. Neither of these manipulations resulted in a significant change in error rate. In a second experiment, participants made fewer errors in delayed pro and antisaccade tasks than in a standard antisaccade task. The implications of these results for current models of antisaccade performance, and the interpretation of antisaccade deficits in clinical populations are discussed.

Dopamine replacement remediates risk aversion in Parkinson's disease in a value-independent manner.

INTRODUCTION: Clinical evidence suggests that Parkinson's Disease (PD) patients are risk averse. Dopaminergic therapy has been reported to increase risk tolerance, but the underlying mechanisms are unclear. Some studies have suggested an amplification of subjective reward value, consistent with the role of dopamine in reward value coding. Others have reported value-independent risk enhancement. We evaluated the value-dependence of the effects of PD and its therapy on risk using tasks designed to sensitively measure risk over a wide range of expected values. METHOD: 36 patients with idiopathic PD receiving levodopa monotherapy and 36 healthy matched controls performed two behavioural economic tasks aimed at quantifying 1) risk tolerance/aversion in the gain frame and 2) valuation of potential gains relative to losses. PD patients performed the tasks on and off their usual dose of levodopa in randomized order; controls performed the same tasks twice. RESULTS: Relative to the controls, unmedicated PD patients showed significant value-independent risk aversion in the gain frame, which was normalized by levodopa. PD patients did not differ from controls in their valuation of gains relative to losses. However, across both tasks and regardless of medication, choices of the patients were more determined by expected values of the prospects than those of controls. CONCLUSION: Dopamine deficiency in PD was associated with risk aversion, and levodopa promoted riskier choice in a value-independent manner. PD patients also showed an increased sensitivity to expected value, which was independent of levodopa and does not appear to result directly from dopamine deficiency.

What makes icons appealing? The role of processing fluency in predicting icon appeal in different task contexts.

Although icons appear on almost all interfaces, there is a paucity of research examining the determinants of icon appeal. The experiments reported here examined the icon characteristics determining appeal and the extent to which processing fluency - the subjective ease with which individuals process information - was used as a heuristic to guide appeal evaluations. Participants searched for, and identified, icons in displays. The initial appeal of icons was held constant while ease of processing was manipulated by systematically varying the complexity and familiarity of the icons presented and the type of task participants were asked to carry out. Processing fluency reliably influenced users' appeal ratings and appeared to be based on users' unconscious awareness of the ease with which they carried out experimental tasks.

The effects of homonymous hemianopia in experimental studies of alexia.

Pure alexia is characterized by an increased word-length effect in reading. However, this disorder is usually accompanied by right homonymous hemianopia, which itself can cause a mildly increased word-length effect. Some alexic studies have used hemianopic patients with modest word-length effects: it is not clear (a) whether they had pure alexia and (b) if not, whether their results could be explained by the field defect. Our goal was to determine if impairments in visual processing claimed to be related to alexia could be replicated in homonymous hemianopia alone. Twelve healthy subjects performed five experiments used in two prior studies of alexia, under both normal and simulated hemianopic conditions, using a gaze-contingent display generated by an eye-tracker. We replicated the increased word-length effect for reading time with right homonymous hemianopia, and showed a similar effect for a lexical decision task. Simulated hemianopia impaired scanning accuracy for letter or number strings, and slowed object part processing, though the effect of configuration was not greater under hemianopic viewing. Hemianopia impaired the identification of words whose letters appeared and disappeared sequentially on the screen, with better performance on a cumulative presentation in which the letters remained on the screen. The reporting of trigrams was less accurate with hemianopia, though syllabic structure did not influence the results. We conclude that some impairments that have been attributed to the processing defects underlying alexia may actually be due to right homonymous hemianopia. Our results underline the importance of considering the contribution of accompanying low-level visual impairments when studying high-level processes.

Visuo-spatial representations of the alphabet in synaesthetes and non-synaesthetes.

Visuo-spatial representations of the alphabet (so-called 'alphabet forms') may be as common as other types of sequence-space synaesthesia, but little is known about them or the way they relate to implicit spatial associations in the general population. In the first study, we describe the characteristics of a large sample of alphabet forms visualized by synaesthetes. They most often run from left to right and have salient features (e.g., bends, breaks) at particular points in the sequence that correspond to chunks in the 'Alphabet Song' and at the alphabet mid-point. The Alphabet Song chunking suggests that the visuo-spatial characteristics are derived, at least in part, from those of the verbal sequence learned earlier in life. However, these synaesthetes are no faster at locating points in the sequence (e.g., what comes before/after letter X?) than controls. They tend to be more spatially consistent (measured by eye tracking) and letters can act as attentional cues to left/right space in synaesthetes with alphabet forms (measured by saccades), but not in non-synaesthetes. This attentional cueing suggests dissociation between numbers (which reliably act as attentional cues in synaesthetes and non-synaesthetes) and letters (which act as attentional cues in synaesthetes only).