Mise à jour le 28 nov. 2022
Publié le 28 novembre 2022 Mis à jour le 28 novembre 2022

Financement ANR
2009 - 2013
Porté par Hanna Chainay

The present proposal aims to study the effects of emotion and attention on memory in Alzheimer's disease (AD). Particularly, we are interested in combined effects of emotion and attention on this function. This is the main novelty of this project. We combine the expertise of researchers with a multidisciplinary scientific basis (cognitive psychology, geriatrics, neuropsychology and neuroimaging) and with multi-domain basis (attention, emotion, memory) in order to respond to the following questions: (1) Do Alzheimer's patients memorize and recognize better emotionally significant information' (2) How attention modulates retention and recognition of emotionally significant information in AD' (3) What is the role of amygdala in retention and recognition of emotionally significant versus emotionally neutral information in AD and normal elderly subjects' Emotions are thought to play an important role in encoding and retrieval of memories, as expressed by emotional memory enhancement (EME) of performance. This enhancement is probably mediated by amygdala, the structure involved in emotional processing. Recent studies point out that pathological changes affect amygdala early in the Alzheimer's disease. Thus it is important to understand the effects of emotional processes on memory in AD. The existing data are rather controversial. Particularly, the nature of the memory task (implicit/explicit) may be involved in a discrepancy of results. The question we ask here has not been systematically investigated to date. Usually, studies examine EME in AD either with explicit or implicit tasks. We propose to investigate this discrepancy by using two experimental tasks and by varying instructions given to subjects in order to cross explicit and implicit encoding with explicit and implicit recall. The tasks will be categorization and recognition of emotionally significant or neutral stimuli. In order to better understand the role of amygdala in the EME a volumetric measure of amygdala will be performed in AD patients and control elderly subjects, and a correlation between its volume and the memory performance will be examined. In addition, we will use the fMRI approach to study implication of amygdala in EME with normal elderly subjects. Attention seems central to all cognitive activities and this raises-up the question of relation between attention and mnemonic processes. Recent studies suggest greater functional and neuropathological changes in the frontal lobes in AD than it was though. Attention deficits in this population are predominant when the situation requires inhibition of irrelevant information or cognitive control over highly active but inappropriate responses, or requires prioritizing of information. Thus, an understanding of AD related changes in memory cannot be achieve without an understanding of AD related changes in selective attention, particularly in inhibition. However, there is few evidence of how impairment of inhibition and impairment of prioritizing might influence memory performance in AD. We will use tasks inspired from psychophysical experimental paradigms. The main paradigm will, in a first part, constrain subjects to respond to some stimuli and to inhibit other according to their physical characteristics. In addition, some of the stimuli will be characterised by priority physical characteristic. In a second part we will investigate subjects' recognition of stimuli in function of their inhibition and their priority physical information. Selective attention may be modulated by emotional nature of the information. Thus, we will study the combined effects of the emotional valence of information and attention abilities of AD patients on their memory performance. The same paradigms, as here above, will be used and in addition we will vary emotional valance of the stimuli. This project, studying influence of emotional and attentional processes on memory in AD, should contribute to a better understanding of memory function in this population. We expect to clarify the discrepancy of results concerning emotional memory enhancement. The second part of this project should precise involvement of inhibitory and prioritizing processes in memory impairment in AD. The third part of this protocol attempts to bring together usually separated investigations. Exploration of combined influences of emotional and attentional processes on memory in AD patients may bring new insight on the memory impairment in these patients and on the normal memory function. Functional neuroimaging study and Voxel Based Morphometry will precise the role of amygdala in memory processes of emotional stimuli. Eventually, better understanding of emotional memory enhancement in Alzheimer's patients may help in elaboration of memory remediation programs.