Lack of contextual-word predictability during reading in patients with mild Alzheimer disease (original) (raw)
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Diagnosis of mild Alzheimer disease through the analysis of eye movements during reading
Journal of Integrative Neuroscience, 2015
Reading requires the integration of several central cognitive subsystems, ranging from attention and oculomotor control to word identi¯cation and language comprehension. Reading saccades and¯xations contain information that can be correlated with word properties. When reading a sentence, the brain must decide where to direct the next saccade according to what has been read up to the actual¯xation. In this process, the retrieval memory brings information about the current word features and attributes into working memory. According to this information, the prefrontal cortex predicts and triggers the next saccade. The frequency and cloze predictability of the¯xated word, the preceding words and the upcoming ones a®ect when and where the eyes will move next. In this paper we present a diagnostic technique for early stage cognitive impairment detection by analyzing eye movements during reading proverbs. We performed a case-control study involving 20 patients with probable Alzheimer's disease and 40 age-matched, healthy control patients. The measurements were analyzed using linear mixed-e®ects models, revealing that eye movement behavior while reading can provide valuable information about whether a person is cognitively impaired. To the best of our knowledge, this is the¯rst study using word-based properties, proverbs and linear mixed-e®ect models for identifying cognitive abnormalities.
Eye Movement Alterations During Reading in Patients With Early Alzheimer Disease
Investigative Ophthalmology & Visual Science, 2013
PURPOSE. Eye movements follow a reproducible pattern during normal reading. Each eye movement ends up in a fixation point, which allows the brain to process the incoming information and to program the following saccade. Alzheimer disease (AD) produces eye movement abnormalities and disturbances in reading. In this work, we investigated whether eye movement alterations during reading might be already present at very early stages of the disease. METHODS. Twenty female and male adult patients with the diagnosis of probable AD and 20 age-matched individuals with no evidence of cognitive decline participated in the study. Participants were seated in front of a 20-inch LCD monitor and single sentences were presented on it. Eye movements were recorded with an eye tracker, with a sampling rate of 1000 Hz and an eye position resolution of 20 arc seconds. RESULTS. Analysis of eye movements during reading revealed that patients with early AD decreased the amount of words with only one fixation, increased their total number of firstand second-pass fixations, the amount of saccade regressions and the number of words skipped, compared with healthy individuals (controls). They also reduced the size of outgoing saccades, simultaneously increasing fixation duration. CONCLUSIONS. The present study shows that patients with mild AD evidenced marked alterations in eye movement behavior during reading, even at early stages of the disease. Hence, evaluation of eye movement behavior during reading might provide a useful tool for a more precise early diagnosis of AD and for dynamical monitoring of the pathology.
Reading Latency of Words and Nonwords in Alzheimer's Patients
Cortex, 2000
Contrasting data on reading ability in Alzheimer's disease patients have been reported in the literature. Recently Patterson, found that irregular words were misread by demented subjects, while regular words were read correctly. The present study hypothesizes that reading latency may be a sensitive measure of Alzheimer's patients reading impairment. Fifteen Alzheimer's patients were compared with 17 elderly normal subjects on three tasks that used the same set of concrete, regular words: a picture naming task, a word-picture matching task and a word-nonword reading task. The results of the study indicate that reading latency is longer in Alzheimer's patients than in normal subjects, and that misnamed and mismatched words are read with the same mechanism as nonwords.
Psychology and aging, 2017
Previous eye-tracking research has characterized older adults' reading patterns as "risky," arguing that compared to young adults, older adults skip more words, have longer saccades, and are more likely to regress to previous portions of the text. In the present eye-tracking study, we reexamined the claim that older adults adopt a risky reading strategy, utilizing the boundary paradigm to manipulate parafoveal preview and contextual predictability of a target word. Results showed that older adults had longer fixation durations compared to young adults; however, there were no age differences in skipping rates, saccade length, or proportion of regressions. In addition, readers showed higher skipping rates of the target word if the preview string was a word than if it was a nonword, regardless of age. Finally, the effect of predictability in reading times on the target word was larger for older adults than for young adults. These results suggest that older adults' rea...
Aphasiology, 2017
Background: Mild reading difficulties are a pervasive symptom of aphasia. Whilst much research in aphasia has been devoted to the study of single word reading, little is known about the process of (silent) sentence reading. Reading research in the non-brain damaged population has benefited from the use of eye tracking methodology, allowing inferences on cognitive processing without participants making an articulatory response. This body of research identified two factors, which strongly influence reading at the sentence level: word frequency and contextual predictability (influence of context).
Length, frequency and predictability effects of words on eye movements in reading
Eye movements and …, 2004
Tested the effects of word length, frequency, and predictability on inspection durations (first fixation, single fixation, gaze duration, and reading time) and inspection probabilities during first-pass reading (skipped, once, twice) for a corpus of 144 German sentences (1138 words) and a subset of 144 target words uncorrelated in length and frequency, read by 33 young and 32 older adults. For corpus words, length and frequency were reliably related to inspection durations and probabilities, predictability only to inspection probabilities. For first-pass reading of target words all three effects were reliable for inspection durations and probabilities. Low predictability was strongly related to second-pass reading. Older adults read slower than young adults and had a higher frequency of regressive movements. The data are to serve as a benchmark for computational models of eye movement control in reading.
Stimulus Contrast and Word Reading Speed in Alzheimer's Disease
Experimental Aging Research, 2005
The oral word reading speed of patients with Alzheimer's disease (AD) and healthy young and older control participants was evaluated across a broad range of stimulus contrast levels in two experiments. The impact of stimulus repetition on reading speed also was examined. It was found that the older adult participants, and particularly the AD patients, were more sensitive to contrast reductions. Each subject group was able to read repeated words more rapidly than novel words but this repetition effect emerged only at lower stimulus contrast levels. It was concluded that AD patients have feature extraction speeds comparable to nondemented older adults but only when the stimuli are presented at a relatively high contrast. These findings suggest that the automatic encoding processes involved in word recognition remain intact in mildly demented AD patients given stimuli of sufficient strength.
Word length, frequency, and predictability count among the most influential variables during reading. Their effects are well-documented in eye movement studies, but pertinent evidence from neuroimaging primarily stem from single-word presentations. We investigated the effects of these variables during reading of whole sentences with simultaneous eye-tracking and functional magnetic resonance imaging (fixation-related fMRI). Increasing word length was associated with increasing activation in occipital areas linked to visual analysis. Additionally, length elicited a U-shaped modulation (i.e., least activation for medium-length words) within a brain stem region presumably linked to eye movement control. These effects, however, were diminished when accounting for multiple fixation cases. Increasing frequency was associated with decreasing activation within left inferior frontal, superior parietal, and occipito-temporal regions. The function of the latter region—hosting the putative visual word form area—was originally considered as limited to sublexical processing. An exploratory analysis revealed that increasing predictability was associated with decreasing activation within middle temporal and inferior frontal regions previously implicated in memory access and unification. The findings are discussed with regard to their correspondence with findings from single-word presentations and with regard to neurocognitive models of visual word recognition, semantic processing, and eye movement control during reading.
Neuropsychologia, 2005
Individuals with semantic dementia (SD) were differentiated neuropsychologically from individuals with dementia of the Alzheimer type (DAT) at very mild-to-mild stages (clinical dementia rating 0.5 or 1). A picture naming and recognition memory experiment provided a particularly useful probe for early identification, with SD individuals showing preserved picture recognition memory and impaired naming, and DAT individuals tending to show the reverse dissociation. The identification of an early SD group provided the opportunity to inform models of reading by exploring the influence of isolated lexical semantic impairment on reading regular words. Results demonstrated prolonged latency in both SD and DAT group reading compared to a control group but exaggerated influence of frequency and length only for the SD group. The SD reading pattern was associated with focal atrophy of the left temporal pole. These cognitive-neuroanatomical findings suggest a role for the left temporal pole in lexical/semantic components of reading and demonstrate that cortical thickness differences in the left temporal pole correlate with prolonged latency associated with increased reliance on sublexical components of reading.