Exploring number space by random digit generation

There is some evidence that human subjects preferentially select small numbers when asked to sample numbers from large intervals "at random”. A retrospective analysis of single digit frequencies in 16 independent experiments with the Mental Dice Task (generation of digits 1-6 during 1min) confirmed the occurrence of small-number biases (SNBs) in 488 healthy subjects. A subset of these experiments suggested a spatial nature of this bias in the sense of a "leftward” shift along the number line. First, individual SNBs were correlated with leftward deviations in a number line bisection task (but unrelated to the bisection of physical lines). Second, in 20 men, the magnitude of SNBs significantly correlated with leftward attentional biases in the judgment of chimeric faces. Finally, cognitive activation of the right hemisphere enhanced SNBs in 20 different men, while left hemisphere activation reduced them. Together, these findings provide support for a spatial component in random number generation. Specifically, they allow an interpretation of SNBs in terms of "pseudoneglect in number space.” We recommend the use of random digit generation for future explorations of spatial-attentional asymmetries in numerical processing and discuss methodological issues relevant to prospective design

Head turns bias the brain's internal random generator

SummaryNumerical and spatial cognition rely on common functional circuits in the parietal lobes of the brain [1]. While previous work has established that the mere perception of numbers can bias a subject's attention in space [2], the method of random digit generation has only recently been introduced to a rapidly growing literature exploring asymmetries in number space [3]. Here we show that human subjects' attempts to generate numbers ‘at random’ are systematically influenced by lateral head turns, which are known to reallocate spatial attention in the outside world. Specifically, while facing left, subjects produced relatively small numbers, whereas while facing right they tended to produce larger numbers. These results support current concepts of parietal cortex as mediating the interplay between spatial attention and abstract thought [4]

Reading on the right when there’s nothing left? Probabilistic tractography reveals hemispheric asymmetry in pure alexia

We present a patient with reading inexpertise and right hemianopia following left posterior cerebral artery (PCA) stroke. We examine the extent of disruption to reading performance and the extent of white matter tract damage relative to a patient with more limited PCA infarction and isolated right hemianopia. We show white matter disconnection of the temporal occipital fusiform cortex in our pure alexia patient. Connectivity-based laterality indices revealed right hemisphere laterality in the alexia patient; this was not associated with improved reading function. We speculate that the degree of premorbid laterality may be a critical factor affecting the extent of reading dysfunction in alexia

The psychological impact of instrumental activities of daily living on people with simulated age-related macular degeneration

BACKGROUND: People with age-related macular degeneration (AMD) can report reduced mental health. There is also evidence that they struggle with daily tasks because of vision loss. AIMS: The purpose of this study was to assess the psychological impact of instrumental activities of daily living on people with simulated AMD. METHOD: Twenty-four normally sighted participants completed 12 household tasks, in a simulated home environment, under a moderate-to-severe AMD simulation. Participants’ psychological state was measured through self-report questionnaires and physiological measurements related to anxiety and stress. Tasks were completed twice, under counterbalanced vision conditions (normal and simulated AMD). RESULTS: Linear mixed models on vision condition (normal versus simulated AMD) and trial order (trial 1 versus trial 2) revealed a significant large negative effect of the AMD simulation on time to complete tasks, and the anxiety, task engagement and distress self-reports (all P 0.177). There were also significant medium-large effects of trial order on time, task incompletion, task errors, and the anxiety and task engagement self-reports (all P 0.130), whereby the results improved during the second attempt at the tasks. No physiological measures were significant (all P > 0.05). CONCLUSIONS: Completing instrumental activities of daily living under an AMD simulation had a negative impact on participants’ self-reported mental state. The observed trial order effects also illuminated how practice with tasks could ease anxiety and stress over time

Parietal cortex connectivity as a marker of shift in spatial attention following continuous theta burst stimulation

Non-invasive brain stimulation is a useful tool to probe brain function and provide therapeutic treatments in disease. When applied to the right posterior parietal cortex (PPC) of healthy participants, it is possible to temporarily shift spatial attention and mimic symptoms of spatial neglect. However, the field of brain stimulation is plagued by issues of high response variability. The aim of this study was to investigate baseline functional connectivity as a predictor of response to an inhibitory brain stimulation paradigm applied to the right PPC. In fourteen healthy adults (9 female, aged 24.8 ± 4.0 years) we applied continuous theta burst stimulation (cTBS) to suppress activity in the right PPC. Resting state functional connectivity was quantified by recording electroencephalography and assessing phase consistency. Spatial attention was assessed before and after cTBS with the Landmark Task. Finally, known determinants of response to brain stimulation were controlled for to enable robust investigation of the influence of resting state connectivity on cTBS response. We observed significant inter-individual variability in the behavioral response to cTBS with 53.8% of participants demonstrating the expected rightward shift in spatial attention. Baseline high beta connectivity between the right PPC, dorsomedial pre-motor region and left temporal-parietal region was strongly associated with cTBS response (R² = 0.51). Regression analysis combining known cTBS determinants (age, sex, motor threshold, physical activity, stress) found connectivity between the right PPC and left temporal-parietal region was the only significant variable (p = 0.011). These results suggest baseline resting state functional connectivity is a strong predictor of a shift in spatial attention following cTBS. Findings from this study help further understand the mechanism by which cTBS modifies cortical function and could be used to improve the reliability of brain stimulation protocols.Jessica Mariner, Tobias Loetscher and Brenton Hordacr

Disentangling input and output-related components of spatial neglect

Spatial neglect is a heterogeneous disorder with a multitude of manifestations and subtypes. Common clinical paper and pencil neglect tests fail to differentiate between these subtypes. For example, neglect patients typically bisect lines to the right. This bias can be caused by an underestimation of the left half of the line (input-related deficit), by the failure to direct actions toward the left side of space (output-related deficit), or by a mixture of these impairments. To disentangle these impairments, we used a test consisting of a line bisection task on a touch screen monitor (manual motor task) and the subsequent judgment of one's own bisection performance (visual perceptual task). It was hypothesized that patients with mainly output-related neglect should be better able to recognize their misbisected lines than patients with purely input-related neglect. In a group of 16 patients suffering from spatial neglect after right brain damage, we found that patients were three times more likely to suffer from a predominantly input-related than from an output-related subtype. The results thus suggest that neglect is typically an input-related impairment. Additional analysis of the line bisection task revealed that temporal (slowness in initiation and execution of contralateral movements) and spatial (insufficient movement amplitude toward the contralesional side) aspects of output-related neglect were mutually unrelated. This independence raises the possibility that a fine-grained differentiation of output-related neglect is required. That is, impairments in lateralized temporal and spatial aspects of movements may underlie different neglect subtypes

Simulating Macular Degeneration to Investigate Activities of Daily Living: A Systematic Review

Purpose: Investigating difficulties during activities of daily living is a fundamental first step for the development of vision-related intervention and rehabilitation strategies. One way to do this is through visual impairment simulations. The aim of this review is to synthesize and assess the types of simulation methods that have been used to simulate age-related macular degeneration (AMD) in normally sighted participants, during activities of daily living (e.g., reading, cleaning, and cooking).Methods: We conducted a systematic literature search in five databases and a critical analysis of the advantages and disadvantages of various AMD simulation methods (following PRISMA guidelines). The review focuses on the suitability of each method for investigating activities of daily living, an assessment of clinical validation procedures, and an evaluation of the adaptation periods for participants.Results: Nineteen studies met the criteria for inclusion. Contact lenses, computer manipulations, gaze contingent displays, and simulation glasses were the main forms of AMD simulation identified. The use of validation and adaptation procedures were reported in approximately two-thirds and half of studies, respectively.Conclusions: Synthesis of the methodology demonstrated that the choice of simulation has been, and should continue to be, guided by the nature of the study. While simulations may never completely replicate vision loss experienced during AMD, consistency in simulation methodology is critical for generating realistic behavioral responses under vision impairment simulation and limiting the influence of confounding factors. Researchers could also come to a consensus regarding the length and form of adaptation by exploring what is an adequate amount of time and type of training required to acclimatize participants to vision impairment simulations

Cognitive rehabilitation for attention deficits following stroke

BackgroundMany survivors of stroke report attentional impairments, such as diminished concentration and distractibility. However, the effectiveness of cognitive rehabilitation for improving these impairments is uncertain.This is an update of the Cochrane Review first published in 2000 and previously updated in 2013.ObjectivesTo determine whether people receiving cognitive rehabilitation for attention problems 1. show better outcomes in their attentional functions than those given no treatment or treatment as usual, and 2. have a better functional recovery, in terms of independence in activities of daily living, mood, and quality of life, than those given no treatment or treatment as usual.Search methodsWe searched the Cochrane Stroke Group Trials Register, CENTRAL, MEDLINE, Embase, CINAHL, PsycINFO, PsycBITE, REHABDATA and ongoing trials registers up to February 2019. We screened reference lists and tracked citations using Scopus.Selection criteriaWe included controlled clinical trials (CCTs) and randomised controlled trials (RCTs) of cognitive rehabilitation for impairments of attention for people with stroke. We did not consider listening to music, meditation, yoga, or mindfulness to be a form of cognitive rehabilitation. We only considered trials that selected people with demonstrable or self‐reported attentional deficits. The primary outcomes were measures of global attentional functions, and secondary outcomes were measures of attentional domains (i.e. alertness, selective attention, sustained attention, divided attention), functional abilities, mood, and quality of life.Data collection and analysisTwo review authors independently selected trials, extracted data, and assessed the risk of bias. We used the GRADE approach to assess the certainty of evidence for each outcome.Main resultsWe included no new trials in this update. The results are unchanged from the previous review and are based on the data of six RCTs with 223 participants. All six RCTs compared cognitive rehabilitation with a usual care control.Meta‐analyses demonstrated no convincing effect of cognitive rehabilitation on subjective measures of attention either immediately after treatment (standardised mean difference (SMD) 0.53, 95% confidence interval (CI) –0.03 to 1.08; P = 0.06; 2 studies, 53 participants; very low‐quality evidence) or at follow‐up (SMD 0.16, 95% CI –0.23 to 0.56; P = 0.41; 2 studies, 99 participants; very low‐quality evidence).People receiving cognitive rehabilitation (when compared with control) showed that measures of divided attention recorded immediately after treatment may improve (SMD 0.67, 95% CI 0.35 to 0.98; P < 0.0001; 4 studies, 165 participants; low‐quality evidence), but it is uncertain that these effects persisted (SMD 0.36, 95% CI –0.04 to 0.76; P = 0.08; 2 studies, 99 participants; very low‐quality evidence). There was no evidence for immediate or persistent effects of cognitive rehabilitation on alertness, selective attention, and sustained attention.There was no convincing evidence for immediate or long‐term effects of cognitive rehabilitation for attentional problems on functional abilities, mood, and quality of life after stroke.Authors' conclusionsThe effectiveness of cognitive rehabilitation for attention deficits following stroke remains unconfirmed. The results suggest there may be an immediate effect after treatment on attentional abilities, but future studies need to assess what helps this effect persist and generalise to attentional skills in daily life. Trials also need to have higher methodological quality and better reporting

The Mobility Assessment Course for the Diagnosis of Spatial Neglect: Taking a Step Forward?

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.Spatial neglect after stroke can be a challenging syndrome to diagnose under standard neuropsychological assessment. There is now sufficient evidence that those affected might demonstrate neglect behavior in everyday settings despite showing no signs of neglect during common neglect tasks. This discrepancy is attributed to the simplified and unrealistic nature of common pen and paper based tasks that do not match the demanding, novel, and complex environment of everyday life. As such, increasing task demands under more ecologically valid scenarios has become an important method of increasing test sensitivity. The main aim of the current study was to evaluate the diagnostic utility of the Mobility Assessment Course (MAC), an ecological task, for the assessment of neglect. If neglect becomes more apparent under more challenging task demands the MAC could prove to be more diagnostically accurate at detecting neglect than conventional methods, particularly as the time from initial brain damage increases. Data collected by Guide Dogs of SA/NT were retrospectively analyzed. The Receiver Operating Characteristic (ROC) curve, a measure of sensitivity and specificity, was used to investigate the diagnostic utility of the MAC and a series of paper and pencil tests in 67 right hemisphere stroke survivors. While the MAC proved to be a more sensitive neglect test (74.2%) when compared to the Star Cancellation (43.3%) and Line Bisection (35.7%) tests, this was at the expense of relatively low specificity. As a result, the ROC curve analysis showed no statistically discernable differences between tasks (p > 0.12), or between subacute and chronic groups for individual tasks (p > 0.45). It is concluded that, while the MAC is an ecologically valid alternative for assessing neglect, regarding its diagnostic accuracy, there is currently not enough evidence to suggest that it is a big step forward in comparison to the accuracy of conventional tests

Factors associated with cognitive decline and delirium after transcatheter aortic valve implantation: Preliminary evidence

Background: Transcatheter aortic valve implantation (TAVI) has become the standard for treating severe symptomatic aortic stenosis in those with prohibitive surgical risk. Cognitive complications, including delirium and cognitive decline are common following TAVI, yet an understanding of pre-procedural factors associated with these outcomes is lacking. This prospective observational study set out to identify geriatric pre-procedural factors associated with post-procedural delirium and cognitive decline in patients undergoing TAVI. / Methods: Cognitive outcomes of TAVI patients aged ≥60 years (N=32) were measured over one-year post-TAVI. Pre-procedural measures included frailty, gait, visual symptoms, voice pitch, dysphagia, blink rate, mood, and sleep. Primary outcomes were post-procedural delirium and cognitive decline. / Results: Delirium was present in 25% of patients over two days following TAVI and 26% experienced cognitive decline in the year post-TAVI. Daily physical activity was a protective factor against cognitive decline, and worse baseline visual memory was associated with delirium. While non-significant and with very large confidence intervals, moderate to large effect sizes were found for associations between slowed gait speed, pre-existing atrial fibrillation, and dysphagia for delirium, and slower gait speed, higher blink rate, pre-existing atrial fibrillation for cognitive decline. / Conclusion: Though underpowered, measures of considerable effect size were identified (although non-significant and with large variability). In larger studies, these novel geriatric factors could further be explored for predicting cognitive complications following TAVI. Improvement of risk prediction for cognitive decline and delirium following TAVI could assist with early identification of those at risk, informing clinical decision-making and allowing for targeted intervention to reduce post-procedural incidence of these complications