Gerardo Fernandez, Facundo Manes, Luis E. Politi, David Orozco, Marcela Schumacher, Liliana Castro, Osvaldo Agamennoni, Nora P. Rotstein. Patients with Mild Alzheimer's Disease Fail When Using Their Working Memory: Evidence from the Eye Tracking Technique. J Alzheimers Dis. 2016.

Patients with Mild Alzheimer’s Disease Fail When Using Their Working Memory: Evidence from the Eye Tracking Technique.

Autores Gerardo Fernandez, Facundo Manes, Luis E. Politi, David Orozco, Marcela Schumacher, Liliana Castro, Osvaldo Agamennoni, Nora P. Rotstein.
Año 2016
Journal  J Alzheimers Dis
Volumen 2016 Jan 13;50(3):827-38. doi: 10.3233
Abstract Patients with Alzheimer’s disease (AD) develop progressive language, visuoperceptual, attentional, and oculomotor changes that can have an impact on their reading comprehension. However, few studies have examined reading behavior in AD, and none have examined the contribution of predictive cueing in reading performance. For this purpose we analyzed the eye movement behavior of 35 healthy readers (Controls) and 35 patients with probable AD during reading of regular and high-predictable sentences. The cloze predictability of words N - 1, and N + 1 exerted an influence on the reader’s gaze duration. The predictabilities of preceding words in high-predictable sentences served as task-appropriate cues that were used by Control readers. In contrast, these effects were not present in AD patients. In Controls, changes in predictability significantly affected fixation duration along the sentence; noteworthy, these changes did not affect fixation durations in AD patients. Hence, only in healthy readers did predictability of upcoming words influence fixation durations via memory retrieval. Our results suggest that Controls used stored information of familiar texts for enhancing their reading performance and imply that contextual-word predictability, whose processing is proposed to require memory retrieval, only affected reading behavior in healthy subjects. In AD patients, this loss reveals impairments in brain areas such as those corresponding to working memory and memory retrieval. These findings might be relevant for expanding the options for the early detection and monitoring in the early stages of AD. Furthermore, evaluation of eye movements during reading could provide a new tool for measuring drug impact on patients’ behavior.
Resumen Los pacientes con enfermedad de Alzheimer desarrollan cambios progresivos en el lenguaje, percepción visual, atención, y cambios oculomotores que pueden tener un impacto en la comprensión de la lectura. En esta investigación evaluamos con tecnología de seguimiento ocular a pacientes con Enfermedad de Alzheimer durante la lectura y sugerimos esta tecnica como una posible nueva herramienta para sumar a las opciones diagnosticas y de seguimiento en las primeras etapas de la enfermedad.

Sedeño L, Couto B, García-Cordero I, Melloni M, Baez S, Morales Sepúlveda JP, Fraiman D, Huepe D, Hurtado E, Matallana D, Kuljis R, Torralva T, Chialvo D, Sigman M, Piguet O, Manes F, Ibanez A. Brain Network Organization and Social Executive Performance in Frontotemporal Dementia. J Int Neuropsychol Soc. 2016.

Brain Network Organization and Social Executive Performance in Frontotemporal Dementia.

Autores Sedeño L, Couto B, García-Cordero I, Melloni M, Baez S, Morales Sepúlveda JP, Fraiman D, Huepe D, Hurtado E, Matallana D, Kuljis R, Torralva T, Chialvo D, Sigman M, Piguet O, Manes F, Ibanez A.
Año 2016
Journal J Int Neuropsychol Soc
Volumen 2016 Feb;22(2):250-62. doi: 10.1017
Abstract Abstract
OBJECTIVES:
Behavioral variant frontotemporal dementia (bvFTD) is characterized by early atrophy in the frontotemporoinsular regions. These regions overlap with networks that are engaged in social cognition-executive functions, two hallmarks deficits of bvFTD. We examine (i) whether Network Centrality (a graph theory metric that measures how important a node is in a brain network) in the frontotemporoinsular network is disrupted in bvFTD, and (ii) the level of involvement of this network in social-executive performance.
METHODS:
Patients with probable bvFTD, healthy controls, and frontoinsular stroke patients underwent functional MRI resting-state recordings and completed social-executive behavioral measures.
RESULTS:
Relative to the controls and the stroke group, the bvFTD patients presented decreased Network Centrality. In addition, this measure was associated with social cognition and executive functions. To test the specificity of these results for the Network Centrality of the frontotemporoinsular network, we assessed the main areas from six resting-state networks. No group differences or behavioral associations were found in these networks. Finally, Network Centrality and behavior distinguished bvFTD patients from the other groups with a high classification rate.
CONCLUSIONS:
bvFTD selectively affects Network Centrality in the frontotemporoinsular network, which is associated with high-level social and executive profile. (JINS, 2016, 22, 250-262).
Resumen En este estudio mostramos, mediante técnicas avanzadas para el estudio de la red cerebral, que la conectividad funcional de las áreas de atrofia (redes fronto-temporo-insulares) de la variante conductual de la demencia frontotemporal (VcDFT) se encuentra selectivamente afectada en comparación a un grupo de controles sanos. Además, esta afectación es específica de la VcDFT ya que estos pacientes también se diferencian de pacientes con accidentes cerebro-vasculares en regiones fronto-insulares. Por último, la alteración de la conectividad de las áreas de atrofia en VcDFT se asocia con déficits característicos de esta enfermedad en procesos cognitivos de alto nivel como las funciones ejecutivas y la cognición social.