Emma Delhaye

University of Liège | ulg · GIGA-CRC In-Vivo Imaging

Although long-term visual memory (LTVM) has a remarkable capacity, the fidelity of its episodic representations can be influenced by at least two intertwined interference mechanisms during the encoding of objects belonging to the same category: the capacity to hold similar episodic traces (e.g., different birds ) and the conceptual similarity of th...

Familiarity is the strange feeling of knowing that something has already been seen in our past. Over the past decades, several attempts have been made to model familiarity using artificial neural networks. Recently, two learning algorithms successfully reproduced the functioning of the perirhinal cortex, a key structure involved during familiarity:...

The perirhinal cortex (PrC) stands among the first brain areas to deteriorate in Alzheimer's disease (AD). This study tests to what extent the PrC is involved in representing and discriminating confusable objects based on the conjunction of their perceptual and conceptual features. To this aim, AD patients and control counterparts performed 3 tasks...

Multiple neuropathological changes are involved in Alzheimer’s disease (AD). The current study investigated the concurrence of neurodegeneration, increased iron content, atrophy, and demyelination in AD. Quantitative multiparameter MRI maps providing neuroimaging biomarkers for myelination and iron content along with synaptic density measurements u...

Initial neuropathology of early Alzheimer’s disease accumulates in the transentorhinal cortex. We review empirical data suggesting that tasks assessing cognitive functions supported by the transenthorinal cortex are impaired as early as the preclinical stages of Alzheimer’s disease. These tasks span across various domains, including episodic memory...

acoby and Whitehouse (JW) (1989) showed that feeling of oldness for words can be manipulated by presenting a prime[1, 2] (repetition; e.g. cat – CAT, or semantic; e.g. cat - DOG) less than 50 ms before the word to be recognised, eliciting more correct (hits) or incorrect (false alarms) recognitions. These ‘old’ responses can rely on familiarity (se...

Concept typicality is a key semantic dimension supporting the categorical organization of items based on their features, such that typical items share more features with other members of their category than atypical items, which are more distinctive. Typicality effects manifest in better accuracy and faster response times during categorization task...

Initial neuropathology of early Alzheimer’s disease accumulates in the transentorhinal cortex. We review empirical data suggesting that tasks that assess cognitive functions supported by the transenthorinal cortex are impaired as early as the preclinical stages of Alzheimer’s disease. These tasks span across various domains, including episodic memo...

Typicality is a key semantic dimension supporting the categorical organization of items based on their features. Typical items share more features with other members of their category than atypical items, which are more distinctive. Typicality influences episodic recollection. Yet, the neural substrates of this effect have never been studied. This...

Recent advances in multivariate neuroimaging analyses have made possible the examination of the similarity of the neural patterns of activations measured across participants, but it has not been investigated yet whether such measure is age-sensitive. Here, in the scanner, young and older participants viewed scene pictures associated with labels. At...

The purpose of this exploratory research is to provide data on synaptopathy in the behavioral variant of frontotemporal dementia (bvFTD). Twelve patients with probable bvFTD were compared to 12 control participants and 12 patients with Alzheimer’s disease (AD). Loss of synaptic projections was assessed with [ ¹⁸ F]UCBH-PET. Total distribution volum...

(GIGA-Cyclotron Research Center -in vivo imaging, University of Liege, Belgium / Cognitive Psychology and Neuropsychology Department, University of Mons, Belgium *The first two authors contributed equally to this presentation) Abstract : Alzheimer's disease patients (AD) show an impairment of recognition memory, mainly characterized by deficient r...

Competitive trace theory holds that semanticization following reactivation is characterised by a fidelity loss in the memory representation due to the competition between different traces formed after each occurrence of a given stimulus. This is manifested in the Mnemonic Similarity Task as an increase in hits and in false recognition of similar lu...

Background The behavioural variant of fronto‐temporal dementia (FTD) is characterized by clinical symptoms including behavioural and cognitive changes and by neurodegenerative involvement of the anterior part of the brain. The objective was to study the in vivo distribution of synaptic loss. Method 12 patients with possible FTD and frontotemporal...

Commented Poster presented at the annual conference of BAPS (Belgian Association of Psychological Sciences) Collaborative research between : - GIGA-Cyclotron Research Center -in vivo imaging, University of Liege, Belgium - Cognitive Psychology and Neuropsychology Department, University of Mons, Belgium The first two authors contributed equally t...

Purpose Loss of brain synapses is an early pathological feature of Alzheimer’s disease. The current study assessed synaptic loss in vivo with positron emission tomography and an 18F-labelled radiotracer of the synaptic vesicle protein 2A, [18F]UCB-H. Methods Twenty-four patients with mild cognitive impairment or Alzheimer’s disease and positive [1...

Recollection allows humans to recall past events in detail, whereas familiarity indicates whether an object, person, or place has been encountered before. The Integrative Memory model describes the distributed and interactive neurocognitive architecture of representations and operations underlying recollection and familiarity (Bastin et al., 2019)....

When recollecting events, older adults typically report similar memory vividness levels as young adults, while they actually retrieve fewer episodic details. This suggests that young and older adults use episodic details differently to calibrate their vividness judgements. Capitalizing on the idea that remembering reactivates brain regions that ini...

Background: Aging is characterized by a decline in associative memory. However, under some conditions, such as in the presence of semantic relatedness within the association, the age-related associative decline can be attenuated. In this study, we evaluated whether the nature of the semantic relationship between the memoranda (taxonomic versus them...

The age-related associative memory deficit can be alleviated, under some conditions, when to-be-remembered associations are semantically related. In this study, we explored the experimental conditions in which older adults benefited from semantic relatedness and those that hindered any associative memory improvement. We did so by manipulating the l...

The detection and processing of novelty plays a critical role in memory function. Despite this, relatively little is known about how novelty influences memory in Alzheimer's disease (AD). This review sought to address whether AD patients are still sensitive to novelty; whether novelty triggers memory processes as is observed in healthy subjects; an...

Humans can recollect past events in details (recollection) and/or know that an object, person or place has been encountered before (familiarity). During the last two decades, there has been intense debate about how recollection and familiarity are organized in the brain. Here, we propose an Integrative Memory model which describes the distributed a...

Objectives: Although the influence of prior knowledge on associative memory in healthy aging has received great attention, it has never been studied in Alzheimer's disease (AD). This study aimed at assessing whether AD patients could benefit from prior knowledge in associative memory and whether such benefit would be related to the integrity of th...

The integrative memory model formalizes a new conceptualization of memory in which interactions between representations and cognitive operations within large-scale cerebral networks generate subjective memory feelings. Such interactions allow to explain the complexity of memory expressions, such as the existence of multiples sources for familiarity...

Unitization, that is, the encoding of an association as one integrated entity, has been shown to improve associative memory in populations presenting with associative memory deficit due to hippocampal dysfunction, such as amnesic patients with focal hippocampal lesions and healthy older adults. One reason for this benefit is that encoding of unitiz...

Unitization, the capacity to encode associations as one integrated entity, can enhance associative memory in populations with an associative memory deficit by promoting familiarity-based associative recognition. Patients with Alzheimer's disease (AD) are typically impaired in associative memory compared with healthy controls but do not benefit from...

Novelty detection is essential to adapt to changes. However, the relationship between novelty detection and visual recognition memory remains unclear. To characterize the temporal dynamics of novelty and its connection to familiarity, we probed early behavioural performance of novelty and familiarity in 31 participants using a speeded go/no-go reco...

Memory for episodic associations declines in aging, ostensibly due to decreased recollection abilities. Accordingly, associative unitization - the encoding of associated items as one integrated entity - may potentially attenuate age-related associative deficits by enabling familiarity-based retrieval, which is relatively preserved in aging. To test...

Aging is accompanied by a decline in associative memory that can, however, be attenuated when associations are unitized at encoding, that is, when they form an integrated entity. Unitization is thought to promote familiarity-based recognition memory, which is preserved in aging. We examined whether preexperimentally unitized associations (compound...

La création d'un souvenir épisodique requiert un encodage des différents éléments composant l'événement cible, ainsi que des associations entre ces éléments individuels afin de former un souvenir global et complexe. Cette capacité à lier les éléments entre eux diminue dans le vieillissement normal engendrant un déclin en mémoire épisodique qualifié...