Prose Reading in Neglect

Attentional and lexical factors underlying word-centred neglect dyslexia errors in healthy readers

Word-centred neglect dyslexia is most commonly conceptualised as a deficit caused by attentional biases within spatially coded internal representations of words. However, recent research has suggested that at least some cases of word-centred neglect dyslexia are unrelated to visuospatial neglect and may instead be modulated by self-inhibition and lexical factors. Here, we set out to provide novel insight into potential underlying mechanisms modulating the occurrence of word-centred lateralised reading errors in healthy participants. A sample of 47 healthy readers completed a novel attentional cueing paradigm in which they sequentially identified lateral cues and read presented words under limited exposure conditions. Reading responses were analysed to determine whether word-centred neglect dyslexia could be simulated in healthy readers, to compare the strengths of induced biases, and to identify systematic differences in lexical characteristics between target words and neglect dyslexia reading errors. Healthy participants produced frequent lateralised reading errors in both horizontal and vertical reading stimuli with > 50% of errors classed as neglect dyslexic. Cues appended to word beginnings elicited significantly more reading errors than cues at word ends, illustrating the interaction between existing reading spatial attentional biases and cue-induced biases. Neglect dyslexia reading errors were found to contain significantly more letters per word and had higher concreteness ratings than target words. These findings demonstrate that word-centred neglect dyslexia can be simulated using attentional cues in healthy readers. These results provide important insight into the mechanisms underlying word-centred neglect dyslexia and further fundamental understanding of this syndrome.

Neglect dyslexia: whole-word and within-word errors with parafoveal and foveal viewing

Patients with left-sided neglect dyslexia often omit whole words positioned on the left, termed whole-word errors, or commit errors on the left-sided letters of words, termed unilateral paralexias. In addition, the errors have been shown to be exacerbated by simultaneously presented distractors, which has been interpreted as a failure of selective attention. In two experiments, we examined the dependency of these error types on parafoveal versus foveal viewing. The first experiment used a paradigm with parafoveal targets and distractors; the second a paradigm with foveal targets and parafoveal distractors. This enabled a separate evaluation of the influences of stimulus position within an egocentric frame, a two-word allocentric frame, and a within-word allocentric frame. First, regarding whole-word errors, we found the expected spatial and distractor effects with parafoveal targets and distractors. With foveal targets and parafoveal distractors, however, the spatial effect was effectively eliminated. Surprisingly, intrusions from the distractor word were common in distractor conditions. This is consistent with an egocentric account and not a two-word allocentric account. Second, we found that unilateral paralexias remained largely consistent regardless of spatial position or the presence of a distractor. Thus, there is a contrast in spatial and distractor effects between whole-word errors and unilateral paralexias. These results are consistent with three distinct deficits: an egocentric deficit across space resulting in whole-word errors, a failure of selective attention that results in whole-word intrusion errors, and a within-word allocentric deficit resulting in unilateral paralexias.

The 3s Spreadsheet Test version 2 for assessing egocentric viewer-centered and allocentric stimulus-centered spatial neglect

The present study established the norms of the 3 s Spreadsheet Test version 2 (3S-v2 Test) with 186 healthy adults, compared performance of 23 individuals with spatial neglect after right brain stroke to the norms, and examined the extent that allocentric neglect is independent from egocentric neglect. The task required in the 3S-v2 Test is to cross out the target digit "3" in a spreadsheet that contained 10 columns and 14 rows of digit strings, including 120 target digits and 720 non-target digits. Each target is categorized with respect to its location on the page (egocentric viewer-centered) and its position within the digit string (allocentric stimulus-centered). Patients completed the 3S-v2 Test, the Apples Test, and Scene Copying Test (a five-object figure copying test). Based on the neglect classification criteria of these three tests, 18 patients (78.3%) were identified with both forms of neglect, three patients (13.0%) had isolated egocentric neglect, and two (8.7%) had isolated allocentric neglect. Among patients who were determined as having allocentric neglect by a given test, we found no significant correlation between severity of allocentric neglect and stimulus location in the egocentric reference frame. Based on the present findings, we suggest that including the 3S-v2 Test, a functionally relevant task and different from the currently available tests, may increase the comprehensiveness of neglect assessment. In addition, allocentric neglect symptoms are independent of egocentric locations.

Reading and alexia

Alexia refers to a reading disorder caused by some form of acquired brain pathology, most commonly a stroke or tumor, in a previously literate subject. In neuropsychology, a distinction is made between central alexia (commonly seen in aphasia) and peripheral alexia (a perceptual or attentional deficit). The prototypical peripheral alexia is alexia without agraphia (pure alexia), where patients can write but are impaired in reading words and letters. Pure alexia is associated with damage to the left ventral occipitotemporal cortex (vOT) or its connections. Hemianopic alexia is associated with less extensive occipital damage and is caused by a visual field defect, which creates problems reading longer words and passages of text. Reading impairment can also arise due to attentional deficits, most commonly following right hemisphere or bilateral lesions. Studying patients with alexia, along with functional imaging studies of normal readers, has improved our understanding of the neurobiological processes involved in reading. A key question is whether an area in the left ventral occipitotemporal cortex is specialized for or selectively involved in word processing, or whether reading relies on tuning of more general purpose perceptual areas. Reading deficits may also be observed in dementia and traumatic brain injury, but often with less consistent deficit patterns than in patients with focal lesions.

Prevalence of spatial neglect post-stroke: A systematic review

OBJECTIVE

Spatial neglect (SN) impedes stroke rehabilitation progress, slows functional recovery, and increases caregiver stress and burden. The estimation of SN prevalence varies widely across studies.

BACKGROUND

We aimed to establish the prevalence of SN based on the injured cerebral hemisphere, recovery stage post-stroke, and diagnostic methodology.

MATERIALS AND METHODS

All journal articles published up to February 27, 2019 from CINAHL, PsycINFO, PubMed and Web of Science were searched. We selected original research articles that described observational studies, included both individuals with left brain damage (LBD) and those with right brain damage (RBD) post-stroke, and reported specific diagnostic methods for SN. All authors reached consensus for the final selection of 41 articles. Time post-stroke, patient selection criteria, study setting, SN diagnostic methods were extracted.

RESULTS

A total of 6324 participants were included: 3411 (54%) with RBD and 2913 (46%) with LBD. Without considering time post-stroke or diagnostic methods, the occurrence rate of SN was 29% (38% after RBD and 18% after LBD). Using ecological assessments resulted in higher prevalence than using tests not directly related to daily life activities (53% vs. 24%). Using methods based on a single-cutoff criterion led to lower occurrence of SN than using multi-test methods (27% vs. 33%). The prevalence decreased from the acute to chronic stage post-stroke.

CONCLUSIONS

The estimated prevalence of SN after unilateral stroke is 30%. SN is more common after RBD than after LBD, but SN after LBD is still quite common. Using ecological assessments and multi-test methods to detect SN is preferred to using a single-cutoff criterion of a test that is not directly related to daily function. The decrease in SN prevalence over time is evident, but the exact prevalence in later stages cannot be estimated. More research is needed to better understand chronic SN.

Dissociating spatial attention from neglect dyslexia: A single case study

Word-centred neglect dyslexia is generally thought to be caused by a visuospatial neglect-like attentional deficit which impacts orientation-canonical representations of visual stimuli. However, the relationship between word-centred neglect dyslexia and more general attentional processes is not well described. Here, we investigated the impact of attentional load manipulations within a case of word-centred neglect dyslexia. This study presents data from a single case, Patient CD, who exhibited ipsilesional word-centred neglect dyslexia in conjunction with severe, contralesional allocentric neglect. CD demonstrated an intact ability to name all letters in visually presented words, but committed neglect dyslexia errors when subsequently asked to read the same word as a whole. The severity of patient CD's neglect dyslexia was not found to be impacted by attentional manipulations. We found no effect of exposure time or visual crowding on the frequency of neglect dyslexia errors. This absence of an apparent, right-lateralised perceptual deficit, comorbid left-lateralised object-centred neglect, and insensitivity to attentional load manipulations suggests that the deficit underlying word-centred neglect dyslexia is not related to broad visuo-spatial attention. These findings suggest that neglect dyslexia and domain-general visuospatial neglect may not be as related as previously asserted.

The Verbal Judgement Task: Normative data of verbal abstract reasoning in a sample of 18- to 40-years old

In this study, normative data for the age-range 18-40 years have been provided for the Verbal Judgment Test (VJT), which underpins abstract reasoning on the basis of four subtests: "Differences", "Proverbs", "Absurdities" and "Classifications". 554 participants (280 males and 274 females) were recruited and the following data were provided: means and standard deviations divided by gender, educational level (8, 13 and 18 years) and age group (18-20 years, 21-25 years, 26-30 years, 31-35 years and 36-40 years) for each subtest and the total score; percentiles for each subtest, divided by age group, and, when appropriate, educational level and/or gender; Rho correlations between age group, gender, educational level, intelligence and VJT scores. Age-, education- and gender differences were also assessed carrying out non parametric tests. Results showed that age and education positively affected performance in the subtests of Differences, Proverbs and Classifications, which are mostly based on previous knowledge, experience, and crystallized intelligence, but did not affect performance in the Absurdities subtest, which encompasses to some extent fluid intelligence. In addition, males showed higher scores than females in the subtests of Differences and Proverbs and in the total VJT, probably reflecting higher knowledge acquisition. Implications for future research are briefly discussed.

Exploratory examination of lexical and neuroanatomic correlates of neglect dyslexia

OBJECTIVE

This study examined lexical and neuroanatomic correlates of reading errors in individuals with spatial neglect, defined as a failure to respond to stimuli in the side of space opposite a brain lesion, causing functional disability.

METHOD

One-hundred and ten participants with left spatial neglect after right-hemisphere stroke read aloud a list of 36 words. Reading errors were scored as "contralesional" (error in the left half of the word) or as "other." The influence of lexical processing on neglect dyslexia was studied with a stepwise regression using word frequency, orthographic neighborhood (number of same length neighbors that differ by 1 letter), bigram and trigram counts (number of words with the same 2- and 3-letter combinations), length, concreteness, and imageability as predictors. MRI/CT images of 92 patients were studied in a voxelwise lesion-symptom analysis (VLSM).

RESULTS

Longer length and more trigram neighbors increased, while higher concreteness reduced, the rate of contralesional errors. VLSM revealed lesions in the inferior temporal sulcus, middle temporal and angular gyri, precuneus, temporal pole, and temporo-parietal white matter associated with the rate of contralesional errors.

CONCLUSIONS

Orthographic competitors may decrease word salience, while semantic concreteness may help constrain the selection of available word options when it is based on degraded information from the left side of the word. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Dissociations within neglect-related reading impairments: Egocentric and allocentric neglect dyslexia

Consistently lateralized reading errors are commonly understood as side-effects of visuospatial neglect impairment. There is however a qualitative difference between systematically omitting full words presented on one side of passages (egocentric neglect dyslexia) and lateralized errors when reading single words (allocentric neglect dyslexia). This study aims to investigate the relationship between egocentric and allocentric neglect dyslexia and visuospatial neglect.

1209 stroke survivors completed standardized reading and cancellation tests. Stringent criteria identified unambiguous cases of allocentric neglect dyslexia (N = 17) and egocentric neglect dyslexia (N = 35). These conditions were found to be doubly dissociated with all cases of egocentric and allocentric neglect dyslexia occurring independently. Allocentric neglect dyslexia was dissociated from both egocentric and allocentric visuospatial neglect. Additionally, two cases of allocentric neglect dyslexia which co-occurred with oppositely lateralized domain-general visuospatial neglect were identified. Conversely, all cases of egocentric neglect dyslexia were found in the presence of domain-general visuospatial neglect. These findings suggest that allocentric neglect dyslexia cannot be fully understood as a consequence of visuospatial neglect. In contrast, we found no evidence for a dissociation between egocentric neglect dyslexia and visuospatial neglect. These findings highlight the need for new, neglect dyslexia specific rehabilitation strategies to be designed and tested.

Impact of visuospatial neglect post-stroke on daily activities, participation and informal caregiver burden: A systematic review

OBJECTIVES

Visuospatial neglect (VSN) is a common cognitive disorder after stroke. The primary aim of this systematic review was to provide an overview of the impact of VSN in 3 aspects: (1) activities of daily living (ADL), (2) participation, and (3) caregiver burden. The second aim was to investigate the differences in studies focusing on populations with mean age<65 versus≥65 years.

METHODS

PubMed, EMBASE, Web of Science, Cochrane Library, Emcare, PsychINFO, Academic Search Premier and CENTRAL were searched systematically. Quality was assessed with the Mixed Methods Appraisal Tool.

RESULTS

Of the 115 included studies, 104 provided outcomes on ADL, 15 on participation (4 studies with mean age≥65), and 2 on caregiver burden (1 study with mean age≥65). Quality assessment yielded scores ranging from 0 to 100%. VSN had a negative impact on ADL (i.e., independence during ADL and performance in self-care, household tasks, reading, writing, walking, wheelchair navigation) and participation (i.e., driving, community mobility, orientation, work). The impact of VSN on fulfilling social roles was unclear. VSN had a negative effect on caregiver burden. We found no clear age-related differences.

CONCLUSIONS AND IMPLICATIONS

VSN has a negative impact not only on patients' independence but particularly on the performance of ADL. Despite the far fewer studies of VSN as compared with ADL, VSN also seems to hamper participation and increase caregiver burden, but further research is needed. Because of the large impact, VSN should be systematically and carefully assessed during rehabilitation. A considerable number of different instruments were used to diagnose VSN. Diagnosing VSN at more than one level [function (i.e., pen-and-paper test), activities, and participation] is strongly recommended. Consensus is needed on how to assess VSN and its negative impact for research and rehabilitation practice.

SYSTEMATIC REVIEW REGISTRATION NO

PROSPERPO Registration No. CRD42018087483.

Disruption of the ascending arousal system and cortical attention networks in post-stroke delirium and spatial neglect

Delirium is an acute attention and cognitive dysfunction, adversely affecting functional outcomes and mortality. As many as half of hospitalized right brain stroke survivors may develop delirium. Further, about 50% of right stroke patients experience spatial neglect, impairing safety and recovery. In this review we explore the brain mechanisms, which may explain the high incidence of delirium and spatial neglect after right-brain stroke. We suggest that brain networks for spatial attention and arousal, composed of ascending projections from the midbrain nuclei and integrating dorsal and ventral cortical and limbic components, may underlie impairments in delirium and spatial neglect. We propose that lateralized deficits in spatial neglect may arise because cortical and limbic components of these functional networks are disproportionally impaired by right-brain strokes, and that spatial neglect may lower the threshold for developing delirium. An improved understanding of the brain basis of delirium and spatial neglect could provide a critical biomarker for initiating preventive care in stroke patients at high risk of hospital morbidity and loss of independence.

Impaired oculo-motor behaviour affects both reading and scene perception in neglect patients

Unilateral spatial neglect (USN) is a common neuropsychological disorder following a right-sided brain lesion. Although USN is mostly characterized by symptoms involving the left hemispace, other symptoms are not left lateralized. Recently, it was shown that patients with neglect dyslexia, a reading disturbance that affects about 40% of USN patients, manifest a non-lateralized impairment of eye movement behaviour in association with their reading deficit when they read aloud and perform non-verbal saccadic tasks (Primativo et al., 2013). In the present paper, we aimed to demonstrate that the eye movement impairment shown by some USN patients reflects a more general oculo-motor disorder that is not confined to orthographic material, the horizontal axis or constrained saccadic tasks. We conjectured that inaccurate oculo-motor behaviour in USN patients indicates the presence of a reading deficit. With this aim we evaluated 20 patients, i.e., 10 right-sided brain-damaged patients without neglect and 10 patients affected by USN. On the basis of the patients' eye movement patterns during a scene exploration task, we found that 4 out of the 10 USN patients presented an abnormal oculo-motor pattern. These same four patients (but not the others) also failed in performing 5 different saccadic tasks and produced neglect dyslexia reading errors in both single words and texts. First, we show that a large proportion of USN patients have inaccurate eye movement behaviour in non-reading tasks. Second, we demonstrate that this exploratory deficit is predictive of the reading impairment. Thus, we conclude that the eye movement deficit prevents reading and impairs the performance on many other perceptual tests, including scene exploration. The large percentage of patients with impaired eye-movement pattern suggests that particular attention should be paid to eye movement behaviour during the diagnostic phase in order to program the best rehabilitation strategy for each patient.