Poster C17, Wednesday, August 21, 2019, 10:45 am – 12:30 pm, Restaurant Hall
Eye Gaze as a Predictor of Visual Confrontation Naming Impairment in Progressive Disorders of Semantic Memory
Maurice Flurie1, Molly Ungrady2, Bonnie Zuckerman1, Daniel Mirman3, Jamie Reilly1;1Temple University, 2University of Pennsylvania, 3University of Edinburgh
Introduction: Progressive naming impairment (i.e., anomia) is among the most debilitating and prominent symptoms of Alzheimer’s Disease (AD) and Primary Progressive Aphasia (PPA). Patterns of naming impairment and analyses of naming errors in these clinical populations have provided integral converging evidence for the contribution of anterior and inferolateral temporal lobe regions to the neurobiology of confrontation naming. AD and PPA patients typically experience temporal lobe pathologies that differ from that of stroke aphasia. In turn, it is believed that patterns of naming in AD and PPA reflect a stronger correlation between ‘naming and knowing’ than is evident in the classical cortical aphasia taxonomy. That is, anomia in PPA tends to have a semantic basis rooted in a fundamental lack of ‘knowing’. As such, anomia in these populations tends to be a powerful proxy measure for semantic memory and its systematic deterioration. Here we examined gaze patterns during visual confrontation naming in patients with PPA or AD over the span of two years. We hypothesized that semantic impairment associated with temporal lobe pathology would compromise core elements of visual feature integration. Thus, evidence for semantic impairment would emerge almost instantaneously prior to lexical access. Methods: We tracked eye movements using a portable table-mounted infrared eye-tracker (RED-M 120 Hz, SMI, Inc) as patients (N=10) named familiar people and objects over the span of two years. We windowed gaze analyses to 2500-3000ms. Responses were classified as either correct or incorrect. We eliminated trials characterized by excessive blinks, off-screen looking, or unscorable responses. These data cleaning procedures yielded 4,110 discrete naming trials. We conducted a logistic mixed effects analysis predicting item accuracy (1 or 0) with diagnosis (AD, svPPA, lvPPA, or bvPPA) and MoCA score included as control variables and eye-tracking measures as fixed effects of interest. The unique effects of the eye-tracking measures were evaluated based on improvement in model fit (change in log-likelihood, aka, likelihood ratio test) when the measure was added to a model that already included the two control variables and the other three eye-tracking measures. The model also included crossed random effects of participants and items. Results: In accordance with our hypothesis, picture naming accuracy was significantly associated with eye movement behavior: fixation count (χ2(1)=10.7, p < 0.01), fixation dispersion (χ2(1)=4.8, p < 0.05), saccade count (χ2(1)=21.2, p < 0.001), and saccade velocity (χ2(1)=26.5, p < 0.001). Specifically, compared to correct responses, incorrect responses were associated with fewer fixations and more fixation dispersion, and more saccades and greater saccade velocity. Conclusion: Abnormal gaze patterns index the PPA patient’s inability to rely on their semantic storage of concepts for confrontation naming. With a reduced number of fixations and increased number of saccades in incorrect responses, individuals were not able rely on their extant knowledge to focus on salient information for automatized naming responses, but rather, labored responses reflecting bottom-up processing. Taken together, these findings provide empirical support for reduction of semantic representation, specifically in the early stages of processing external information.
Themes: Disorders: Acquired, Control, Selection, and Executive Processes
Method: Eye Tracking