Gerardo Fernández

Eye movements during reading proverbs and regular sentences: the incoming word predictability effect

Reading is an everyday activity requiring the efficient integration of several central cognitive subsystems ranging from attention and oculomotor control to word identification and language comprehension. Effects of frequency, length and cloze predictability of words on reading times reliably indicate local processing difficulty of fixated words; also, a readers expectation about an upcoming word apparently influences fixation duration even before the eyes reach this word. Moreover, this effect has been reported as non-canonical (i.e., longer fixation durations on word N when word N+1 is of high cloze predictability). However, this effect is difficult to observe because in natural sentences the fluctuations in predictability in content words are very small. To overcome this difficulty we investigated eye movements while reading proverbs as well as sentences constructed for high- and low-average cloze predictability. We also determined for each sentence a word at which predictability of words jumps from a low to high value. Fixation durations while reading proverbs and high-predictable sentences exhibited significant effects of the change in predictability along the sentence (when the successive word is more predictable than the fixated word). Results are in agreement with the proposal that cloze predictability of upcoming words exerts an influence on fixation durations via memory retrieval.

Registering eye movements during reading in Alzheimer’s disease: Difficulties in predicting upcoming words

Reading requires the fine integration of attention, ocular movements, word identification, and language comprehension, among other cognitive parameters. Several of the associated cognitive processes such as working memory and semantic memory are known to be impaired by Alzheimer’s disease (AD). This study analyzes eye movement behavior of 18 patients with probable AD and 40 age-matched controls during Spanish sentence reading. Controls focused mainly on word properties and considered syntactic and semantic structures. At the same time, controls’ knowledge and prediction about sentence meaning and grammatical structure are quite evident when we consider some aspects of visual exploration, such as word skipping, and forward saccades. By contrast, in the AD group, the predictability effect of the upcoming word was absent, visual exploration was less focused, fixations were much longer, and outgoing saccade amplitudes were smaller than those in controls. The altered visual exploration and the absence of a contextual predictability effect might be related to impairments in working memory and long-term memory retrieval functions. These eye movement measures demonstrate considerable sensitivity with respect to evaluating cognitive processes in Alzheimer’s disease. They could provide a user-friendly marker of early disease symptoms and of its posterior progression.

Diagnosis of mild Alzheimer disease through the analysis of eye movements during reading.

Reading requires the integration of several central cognitive subsystems, ranging from attention and oculomotor control to word identification and language comprehension. Reading saccades and fixations 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 fixation. 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 fixated word, the preceding words and the upcoming ones affect 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 Alzheimers disease and 40 age-matched, healthy control patients. The measurements were analyzed using linear mixed-effects 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 first study using word-based properties, proverbs and linear mixed-effect models for identifying cognitive abnormalities.

Eye Movement Alterations During Reading in Patients With Early Alzheimer Disease

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 first- and 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.

Lack of contextual-word predictability during reading in patients with mild Alzheimer disease

In the present work we analyzed the effect of contextual word predictability on the eye movement behavior of patients with mild Alzheimer disease (AD) compared to age-matched controls, by using the eyetracking technique and lineal mixed models. Twenty AD patients and 40 age-matched controls participated in the study. We first evaluated gaze duration during reading low and highly predictable sentences. AD patients showed an increase in gaze duration, compared to controls, both in sentences of low or high predictability. In controls, highly predictable sentences led to shorter gaze durations; by contrary, AD patients showed similar gaze durations in both types of sentences. Similarly, gaze duration in controls was affected by the cloze predictability of word N and N+1, whereas it was the same in AD patients. In contrast, the effects of word frequency and word length were similar in controls and AD patients. Our results imply that contextual-word predictability, whose processing is proposed to require memory retrieval, facilitated reading behavior in healthy subjects, but this facilitation was lost in early AD patients. This loss might reveal impairments in brain areas such as those corresponding to working memory, memory retrieval, and semantic memory functions that are already present at early stages of AD. In contrast, word frequency and length processing might require less complex mechanisms, which were still retained by AD patients. To the best of our knowledge, this is the first study measuring how patients with early AD process well-defined words embedded in sentences of high and low predictability. Evaluation of the resulting changes in eye movement behavior might provide a useful tool for a more precise early diagnosis of AD.

Patients with mild Alzheimer’s disease produced shorter outgoing saccades when reading sentences

In the present work we analyzed forward saccades of thirty five elderly subjects (Controls) and of thirty five mild Alzheimers disease (AD) during reading regular and high-predictable sentences. While they read, their eye movements were recorded. The pattern of forward saccade amplitudes as a function of word predictability was clearly longer in Controls. Our results suggest that Controls might use stored information of words for enhancing their reading performance. Further, cloze predictability increased outgoing saccades amplitudes, as this increase stronger in high-predictable sentences. Quite the contrary, patients with mild AD evidenced reduced forward saccades even at early stages of the disease. This reduction might reveal impairments in brain areas such as those corresponding to working memory, memory retrieval, and semantic memory functions that are already present at early stages of AD. Our findings might be relevant for expanding the options for the early detection and monitoring of in the early stages of AD. Furthermore, eye movements during reading could provide a new tool for measuring a drugs impact on patients behavior.

Word processing during reading sentences in patients with schizophrenia: evidences from the eyetracking technique

PURPOSE The current study analyze the effect of word properties (i.e., word length, word frequency and word predictability) on the eye movement behavior of patients with schizophrenia (SZ) compared to age-matched controls. METHOD 18 SZ patients and 40 age matched controls participated in the study. Eye movements were recorded during reading regular sentences by using the eyetracking technique. Eye movement analyses were performed using linear mixed models. FINDINGS Analysis of eye movements revealed that patients with SZ decreased the amount of single fixations, increased their total number of second pass fixations compared with healthy individuals (Controls). In addition, SZ patients showed an increase in gaze duration, compared to Controls. Interestingly, the effects of current word frequency and current word length processing were similar in Controls and SZ patients. The high rate of second pass fixations and its low rate in single fixation might reveal impairments in working memory when integrating neighbor words. In contrast, word frequency and length processing might require less complex mechanisms, which were functioning in SZ patients. CONCLUSION To the best of our knowledge, this is the first study measuring how patients with SZ process dynamically well-defined words embedded in regular sentences. The findings suggest that evaluation of the resulting changes in eye movement behavior may supplement current symptom-based diagnosis.

Helping Hispanic Dementia Caregivers Cope with Stress Using Technology-Based Resources

ABSTRACT Objectives: The objectives of this study were to develop and evaluate a culturally appropriate intervention for Hispanic/Latino caregivers of individuals with dementia, using a structured online program without professional involvement to improve well-being, decrease stress, and reduce depression. Methods: The Webnovela Mirela, an online Spanish-language telenovela, was designed specifically to teach caregivers how to cope with dementia caregiving. A prototype of Webnovela Mirela was tested in a pilot study with 25 Hispanic/Latino dementia caregivers, 19 of whom completed the study. Results: Data were analyzed using paired-samples t-tests. Results indicated a significant decrease from pre- to post-treatment in levels of stress and symptoms of depression (p = .045). Conclusions: The pilot study indicated high potential of the Webnovela Mirela to help the target population and demonstrated that the telenovela format is acceptable and helpful for Hispanic dementia caregivers. Clinical Implications: Study outcomes suggested that self-paced approaches with culturally relevant content in an appealing format for the target population have the potential to implement effective interventions. Furthermore, technology enables support programs to reach a broader audience in a cost-effective manner. Of note is the fact that minimal professional and/or personal assistance was required for caregivers to complete this intervention.

Contextual predictability enhances reading performance in patients with schizophrenia

In the present work we analyzed fixation duration in 40 healthy individuals and 18 patients with chronic, stable SZ during reading of regular sentences and proverbs. While they read, their eye movements were recorded. We used lineal mixed models to analyze fixation durations. The predictability of words N-1, N, and N+1 exerted a strong influence on controls and SZ patients. The influence of the predictabilities of preceding, current, and upcoming words on SZ was clearly reduced for proverbs in comparison to regular sentences. Both controls and SZ readers were able to use highly predictable fixated words for an easier reading. Our results suggest that SZ readers might compensate attentional and working memory deficiencies by using stored information of familiar texts for enhancing their reading performance. The predictabilities of words in proverbs serve as task-appropriate cues that are used by SZ readers. To the best of our knowledge, this is the first study using eyetracking for measuring how patients with SZ process well-defined words embedded in regular sentences and proverbs. Evaluation of the resulting changes in fixation durations might provide a useful tool for understanding how SZ patients could enhance their reading performance.

OCULOMOTOR RESPONSES PROVIDE EVIDENCE OF NEURODEGENERATIVE MECHANISMS UNDERPINNING MEMORY BINDING IMPAIRMENTS IN ALZHEIMER’S DISEASE

be useful as diagnostic and prognostic biomarkers for FTD. Methods: EV-associated microRNA levels were determined in 96 CSF samples from patients within the FTD spectrum (9 with semantic variant-FTD; 28 with behavioral variant-FTD; 11 with motor neuron disease-FTD), 20 patients with Alzheimer’s disease and 28 neurologically healthy controls. EVs were characterized by bead-based flow cytometry, using three exosome markers: tetraspanins CD9, CD63 and CD81. MicroRNA levels were quantified by quantitative real-time PCR, using oligonucleotides with Locked Nucleid Acids. The study comprised a screening (752-microRNA panels) in a subset of samples and a subsequent analysis of potential candidates (26-microRNA panels) in the whole study group. Results:All three tetraspanins were present in the EV-enriched fraction isolated from 250mL CSF [Fig1]. The amount of RNA extracted from the EV-enriched fraction proved to be enough to obtain a consistent signal for microRNA quantification. Up to 130 EV-associated microRNAs (17.3%) were detected in CSF [Fig2]. A total of 26 microRNAs from the screening were selected for further analysis, including previously described microRNAs related to FTD proteins, such as miR-9, miR-34c, miR-107 and miR-124 [Fig3]. Few candidate microRNAs appeared to be differently expressed in healthy controls and FTD patients. Conclusions: The use of highly sensitive techniques allows the detection of EV-associated microRNAs in small volumes of biofluids. Differences in the microRNA profile between healthy controls and FTD patients show their potential as diagnostic biomarkers. Further studies are warranted to assess their possible role as biomarkers and to disentangle the mechanisms involved in the etiology of FTD.