Untangling letter confusability and word length effects in pure alexia.

Pure alexia is an acquired neuropsychological disorder that follows damage to the occipito-temporal lobe. This brain damage results in a severe reading impairment in which previously literate individuals are no longer able to efficiently read words, but are still able to perform other language tasks. The present study sought to identify factors of words that make it more difficult for pure alexic individuals to read, such as letter confusability and word length. Eye-tracking methodology was paired with a naming task to examine whether word length or letter confusability is a better predictor of processing difficulty. It was found that word length was a significant predictor of reading time, while summed letter confusability was not significant. This study contradicts some previous research and shows that when an orthogonal set of stimuli is used, letter confusability is not a significant factor driving this reading impairment in all individuals with pure alexia.

Classroom demonstration of the visual effects of eye diseases.

An understanding of the visual system is a fundamental aspect of many neuroscience and psychology courses. These classes often cover a variety of visual diseases that are correlated with the anatomy of the visual system, e.g., cataracts are caused by a clouding of the lens. Here, we describe an easy way to modify standard laboratory glasses/goggles to simulate the various perceptual deficits that accompany vision disorders such as astigmatism, cataracts, diabetic retinopathy, glaucoma, optic neuritis, posterior vitreous detachment, and retinitis pigmentosa. For example, when teaching about cataracts, students can put on glasses that mimic how severe cataracts affect one's vision. Using the glasses will allow students to draw connections between the disorder, its perceptual deficits, and the underlying anatomy. We also discuss floaters in the eye and provide an easy method to allow students to detect their own floaters. Together, these demonstrations make for a more dynamic and interactive class on the visual system that will better link diseases of the eye to anatomy and perception, and allow undergraduate students to develop a better understanding of the visual system as a whole.

Virtual Reality Tools for Assessing Unilateral Spatial Neglect: A Novel Opportunity for Data Collection.

Unilateral spatial neglect (USN) is a syndrome characterized by inattention to or inaction in one side of space and affects between 23-46% of acute stroke survivors. The diagnosis and characterization of these symptoms in individual patients can be challenging and often requires skilled clinical staff. Virtual reality (VR) presents an opportunity to develop novel assessment tools for patients with USN. We aimed to design and build a VR tool to detect and characterize subtle USN symptoms, and to test the tool on subjects treated with inhibitory repetitive transcranial magnetic stimulation (TMS) of cortical regions associated with USN. We created three experimental conditions by applying TMS to two distinct regions of cortex associated with visuospatial processing- the superior temporal gyrus (STG) and the supramarginal gyrus (SMG) - and applied sham TMS as a control. We then placed subjects in a virtual reality environment in which they were asked to identify the flowers with lateral asymmetries of flowers distributed across bushes in both hemispaces, with dynamic difficulty adjustment based on each subject's performance. We found significant differences in average head yaw between subjects stimulated at the STG and those stimulated at the SMG and marginally significant effects in the average visual axis. VR technology is becoming more accessible, affordable, and robust, presenting an exciting opportunity to create useful and novel game-like tools. In conjunction with TMS, these tools could be used to study specific, isolated, artificial neurological deficits in healthy subjects, informing the creation of VR-based diagnostic tools for patients with deficits due to acquired brain injury. This study is the first to our knowledge in which artificially generated USN symptoms have been evaluated with a VR task.

The Relationship Between Multiple Sclerosis Symptom Severity Measures and Performance on Driving Variability Metrics in a Virtual Reality Simulator.

OBJECTIVE: Driving ability can be compromised in individuals with multiple sclerosis (MS); however, the progressive nature of multiple sclerosis makes it difficult for clinicians to assess when performance on functional tasks, such as driving, has started to decline. The aim of the study was to evaluate the relationship between two measures of multiple sclerosis severity, the Expanded Disability Status Scale and the Multiple Sclerosis Functional Composite, and minor driving errors in a virtual reality driving simulator. DESIGN: Symptom severity was measured in 31 active drivers with multiple sclerosis using the Expanded Disability Status Scale and Multiple Sclerosis Functional Composite. Driving performance was measured using a standardized virtual reality driving simulator route. Executive functioning, a cognitive function commonly related to driving, was evaluated using the Trail Making Test B. RESULTS: Greater impairment on the Multiple Sclerosis Functional Composite was related to increased difficulty maintaining lane positioning (r = -0.49, P = 0.01) and poorer executive functioning (r = -0.52, P < 0.01). In contrast, the Expanded Disability Status Scale was not related to either measure. CONCLUSIONS: These findings suggest that poorer performance on the Multiple Sclerosis Functional Composite, and not the Expanded Disability Status Scale, may indicate vulnerability to minor driving errors as an early sign of driving compromise. The use of screening tools, such as the Multiple Sclerosis Functional Composite, could help clinicians identify increased driving risk and consider comprehensive driving evaluations earlier, before a major driving violation or accident occurs. TO CLAIM CME CREDITS: Complete the self-assessment activity and evaluation online at http://www.physiatry.org/JournalCME CME OBJECTIVES: Upon completion of this article, the reader should be able to: (1) Describe the relationship between symptom severity and driving performance in a virtual reality driving simulator, and how the relationship may vary based on which symptom severity measure is used; (2) Identify nuanced differences between two commonly used multiple sclerosis (MS) symptom severity measures when assessing functional abilities such as driving; and (3) Utilize symptom severity screeners that can assist in monitoring symptom progression and assessing whether further driving evaluation is needed. LEVEL: Advanced. ACCREDITATION: The Association of Academic Physiatrists is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.The Association of Academic Physiatrists designates this Journal-based CME activity for a maximum of 1.0 AMA PRA Category 1 Credit(s)™. Physicians should only claim credit commensurate with the extent of their participation in the activity.