References of "Genon, Sarah"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailDisrupted Self in Alzheimer’s disease: beyond midline structures: Commentary on Wong et al.
Genon, Sarah ULiege; Salmon, Eric

in Cortex : A Journal Devoted to the Study of the Nervous System & Behavior (in press)

Detailed reference viewed: 24 (3 ULiège)
Full Text
Peer Reviewed
See detailThe heterogeneity of the left dorsal premotor cortex evidenced by multimodal connectivity-based parcellation and functional characterization
Genon, Sarah ULiege; Reid, Andrew; Li, Hai et al

in NeuroImage (in press)

Despite the common conception of the dorsal premotor cortex (PMd) as a single brain region, its diverse connectivity profiles and behavioral heterogeneity argue for a differentiated organization of the ... [more ▼]

Despite the common conception of the dorsal premotor cortex (PMd) as a single brain region, its diverse connectivity profiles and behavioral heterogeneity argue for a differentiated organization of the PMd. A previous study revealed that the right PMd is characterized by a rostro-caudal and a ventro-dorsal distinction dividing it into five subregions: rostral, central, caudal, ventral and dorsal. The present study assessed whether a similar organization is present in the left hemisphere, by capitalizing on a multimodal data-driven approach combining connectivity-based parcellation (CBP) based on meta-analytic modeling, resting- state functional connectivity, and probabilistic diffusion tractography. The resulting PMd modules were then characterized based on multimodal functional connectivity and a quantitative analysis of associated behavioral functions. Analyzing the clusters consistent across all modalities revealed an organization of the left PMd that mirrored its right counterpart to a large degree. Again, caudal, central and rostral modules reflected a cognitive- motor gradient and a premotor eye-field was found in the ventral part of the left PMd. In addition, a distinct module linked to abstract cognitive functions was observed in the rostro- ventral left PMd across all CBP modalities, implying greater differentiation of higher cognitive functions for the left than the right PMd. [less ▲]

Detailed reference viewed: 41 (1 ULiège)
Peer Reviewed
See detailSelf in Dementia
Antoine, Nicolas ULiege; Genon, Sarah ULiege; Bastin, Christine ULiege et al

in Mishara; Corlett, P.; Fletcher, P. (Eds.) et al Phenomenological Neuropsychiatry, How Patient Experience Bridges Clinic with Clinical Neuroscience (in press)

Detailed reference viewed: 150 (31 ULiège)
Full Text
Peer Reviewed
See detailEvaluation of Non-negative matrix Factorization of grey matter in age prediction
Varikuti, Deepthi; Genon, Sarah ULiege; Sotiras, Aristeidis et al

Poster (2017, June)

Introduction: It has been shown that machine-learning methods applied to voxel-based morphometry (VBM) data allows the prediction of brain age [1]. Dimensionality reduction is a critical aspect of such ... [more ▼]

Introduction: It has been shown that machine-learning methods applied to voxel-based morphometry (VBM) data allows the prediction of brain age [1]. Dimensionality reduction is a critical aspect of such brain-based prediction of phenotypical characteristics to counter the curse of dimensionality associated with voxel-wise analysis. While previous age-predictions have employed PCA based compression, non-negative matrix factorization (NNMF) has recently been suggested as a plausible factorization of high-dimensional VBM data [4]. Non-negativity and sparsity of the components obtained from NNMF facilitate relatively more optimal solution than the PCA based compression [4]. Here, we evaluate, i) whether NNMF compression allows predictions of biological age that reproduce those from previously reported analyses [2], ii) the impact of the NNMF’s granularity on the prediction accuracy, iii) the possible effect of the factorizations derived from different datasets on the prediction, and iv) whether explicit adjustment can address the model bias inherent to many brain-based predictions. Methods: VBM8 preprocessing (using only non-linear modulation and 8 mm FWHM smoothing [3]) was used to compute voxel-wise GM volumes for two datasets, 1) 693 healthy older adults (age: 55-75 years) scanned at a single site (“1000BRAINS) [1], 2) 1084 healthy adults (age: 18-81 years), scanned at multiple sites (“Mixed”) (Fig 1A). NNMF solutions for both groups were derived at different levels of granularity. Age prediction was performed by fitting LASSO regression models either on the coefficient matrix from the respective NNMF or by those that were derived from projecting a group’s data on the respective other groups components. Model generalization was evaluated by 10-fold cross-validation replicated 25 times. To address the known bias towards the mean, i.e., overestimation of young and underestimation of older subjects, we additionally tested models that explicitly fitted the regression-slope between the real and predicted training set and used this to adjust the expected slope of the test set to 45 degrees. Results: In both datasets, NNMF components resembled neurobiologically reasonable patterning of the brain (Fig 1B). Prediction accuracy based on the projection of data on the components from either group was virtually identical (Fig 2A). For both datasets, mean absolute errors (MAE) declined with higher granularity of the components and reached values well comparable to previous approaches even when using components derived from an independent sample (MAE: 3.6 years for 1000BRAINS; 6.4 years for Mixed). Plotting the prediction error relative to the biological age of the subjects revealed the bias towards the mean across both datasets (Fig 2B). Adjusting for the slope estimated in the training set allows removing this bias, though it needs to be noted that this comes at the cost of reduced precision, i.e., unbiased estimates yield a slightly higher MAE. Conclusion: NNMF allows the definition of co-variation patterns in VBM data. Due to the non- negativity and sparseness, NNMF enable substantially easier and higher biological interpretation than other methods for data compression such as PCA [4]. We showed that NNMF compression of VBM data over the lifespan allows predicting previously unseen subjects’ age with a precision that is comparable to earlier reports using PCA for data compression [2], while offering the potential for neurobiological interpretation. Importantly, accuracy seems to be independent of whether the components were derived from the same dataset or from a dataset that is not only independent but also different in age distribution. We note that accuracies tend to continuously decrease with higher granularity, although performance tends to plateau at about 300 components. Finally, adjusting the inherent bias of sparse regression models yields unbiased out-of-sample predictions but comes at the expense of slightly higher mean errors. [less ▲]

Detailed reference viewed: 56 (2 ULiège)
Full Text
Peer Reviewed
See detailProfiling inferior left dorsal premotor cortex: when Area 55b meets Premotor Eye-Field
Genon, Sarah ULiege; Reid, Andrew; Langner, Robert et al

Poster (2017, June)

Detailed reference viewed: 31 (1 ULiège)
Full Text
See detailMétacognition lors de la récupération en mémoire chez les patients Alzheimer
Genon, Sarah ULiege

Scientific conference (2017, May 19)

Detailed reference viewed: 28 (2 ULiège)
Full Text
Peer Reviewed
See detailAnosognosia for behavioral disorder is related to confidence for false self-related memories in Alzheimer’s disease
Mélon, Marlène; Collette, Fabienne ULiege; Salmon, Eric ULiege et al

Poster (2017, March 24)

Impaired self-awareness (i.e. anosognosia) and altered metacognitive monitoring in memory tasks have both been evidenced in AD. Furthermore, cognitive studies showed disrupted interaction between self and ... [more ▼]

Impaired self-awareness (i.e. anosognosia) and altered metacognitive monitoring in memory tasks have both been evidenced in AD. Furthermore, cognitive studies showed disrupted interaction between self and memory cognitive systems in AD, reducing cognitive advantages of self-related memories (i.e. decreasing self reference effect, SRE) in these patients. However, how anosognosia relates to impaired metacognitive monitoring in AD, particularly for self-related memories, is still an open question. To investigate this question, an ecological memory task based on face-name associations was administrated to 20 healthy older controls (HC) and 20 mild AD patients. The influence of self-reference at encoding was assessed on subsequent name recall and recollective experience, as well as on predictive (feeling-of-knowing, FOK) and postretrieval (judgments-of-confidence, JOC) metacognitive judgments on name recognition in all participants. Furthermore relationships between metacognitive outcomes and awareness of daily cognitive and behavioral impairment was examined in AD. Altered SRE was evidenced in name recall and recollective experience in AD. Patients also showed impaired FOK and JOC, as well as lower awareness of their daily functioning impairment (anosognosia). Nevertheless, differential effect of self on metacognitive judgment in AD and HC was only observed on JOC for false memories. Importantly, anosognosia for behavioral disorders was related to post-retrieval confidence for false recognition of self-related items in AD patients. Thus, anosognosia concerning behavioral disorder and altered post-retrieval monitoring of self-related memories appear to be related in AD. We hypothesized that impaired monitoring of personal false memories may lead AD patients to rely on distorted recent reality when providing judgment about their everyday behavioral functioning. [less ▲]

Detailed reference viewed: 71 (1 ULiège)
Full Text
Peer Reviewed
See detailRelating pessimistic memory predictions to Alzheimer’s disease brain structure
Genon, Sarah ULiege; Simon, Jessica ULiege; Bahri, Mohamed Ali ULiege et al

Poster (2017, March 23)

Patients with Alzheimer’s disease (AD) show impairment of episodic memory and related metacognitive processes. The present study examined subjective metacognitive judgments preceding objective memory ... [more ▼]

Patients with Alzheimer’s disease (AD) show impairment of episodic memory and related metacognitive processes. The present study examined subjective metacognitive judgments preceding objective memory retrieval and investigated the neural correlates of pessimistic predictions for successfully retrieved memories in AD patients. AD patients and healthy older participants provided predictive judgements on their recognition performance before retrieval of famous (semantic) and recently learned (episodic) names. Correlations between grey matter volume (GMV) in T1 images and behavioural scores were examined with multivariate (PLS) and univariate (GLM) analyses in AD patients. AD patients showed a significant proportion of successful name recognition preceded by pessimistic prediction (Prediction_low_hits) in episodic memory. PLS revealed that behavioural pattern in AD patients was related with a mainly right lateralized pattern of GMV decrease including medial temporal lobe and posterior cingulate cortex, but also right ventrolateral prefrontal cortex (VLPFC). GLM further confirmed that pessimistic prediction negatively correlated with GMV in VLPFC. Thus, impaired monitoring processes (possibly influenced by inaccurate beliefs) allowing inferences about one’s own memory performance are primarily related to decrease GMV in VLPFC in AD patients. [less ▲]

Detailed reference viewed: 37 (2 ULiège)
Full Text
Peer Reviewed
See detailSearching for behavior relating to grey matter volume in a-priori defined right dorsal premotor regions: lessons learned.
Genon, Sarah ULiege; Wensing, Tobias; Reid, Andrew et al

in NeuroImage (2017)

Recently, we showed that the functional heterogeneity of the right dorsal premotor (PMd) cortex could be better understood by dividing it into five subregions that showed different behavioral associations ... [more ▼]

Recently, we showed that the functional heterogeneity of the right dorsal premotor (PMd) cortex could be better understood by dividing it into five subregions that showed different behavioral associations according to task-based activations studies. The present study investigated whether the revealed behavioral profile could be corroborated and complemented by a structural brain behavior correlation approach in two healthy adults cohorts. Grey matter volume within the five volumes of interest (VOI-GM) was computed using voxel-based morphometry. Associations between the inter-individual differences in VOI-GM and performance across a range of neuropsychological tests were assessed in the two cohorts with and without correction for demographical variables. Additional analyses were performed in random smaller subsamples drawn from each of the two cohorts. In both cohorts, correlation coefficients were low; only few were significant and a considerable number of correlations were counterintuitive in their directions (i.e., higher performance related to lower GMV). Furthermore, correlation patterns were inconsistent between the two cohorts. Subsampling revealed that correlation patterns could vary widely across small samples and that negative correlations were as likely as positive correlations. Thus, the structural brain/behavior approach did not corroborate the functional profiles of the PMd subregions inferred from activation studies, suggesting that local recruitment by fMRI studies does not necessarily imply covariance of local structure with behavioral performance in healthy adults. We discuss the limitations of such studies and related recommendations for future studies. [less ▲]

Detailed reference viewed: 27 (4 ULiège)
Full Text
See detailCo-activation mapping and Parcellation
Genon, Sarah ULiege; Müller, Veronika; Eickhoff, Simon

Learning material (2017)

Detailed reference viewed: 10 (1 ULiège)
Full Text
Peer Reviewed
See detailAnosognosie et monitoring des souvenirs associés au « soi » dans la Maladie d’Alzheimer
Genon, Sarah ULiege; Mélon, Marlène; Collette, Fabienne ULiege et al

Conference (2017)

Chez les patients atteints de maladie d’Alzheimer (MA), on observe dès les stades débutants d’une part un phénomène d’anosognosie, qui peut être considéré comme une altération de la conscience de soi, et ... [more ▼]

Chez les patients atteints de maladie d’Alzheimer (MA), on observe dès les stades débutants d’une part un phénomène d’anosognosie, qui peut être considéré comme une altération de la conscience de soi, et d’autre part un dysfonctionnement des processus de monitoring mnésique [1]. En outre, l’interaction entre le soi et la mémoire (conférant un bénéfice mnésique pour les informations associées à soi), apparaît significativement altérée dans la MA. Dans la présente étude, nous avons examiné les relations entre l’anosognosie et le monitoring lors de la récupération en mémoire d’informations expérimentalement associées à soi. Nous avons évalué les processus de monitoring lors de la récupération en mémoire à l’aide d’une tâche expérimentale de 32 paires visage-prénom, ainsi que l’anosognosie à l’aide du questionnaire d’anosognosie dans la démence (AQD, [2]) chez 20 patients MA et 20 personnes âgées contrôles (AC). Durant la phase d’encodage, les paires visage-prénom ont été présentées aux participants soit comme des personnes faisant partie de leur famille (soi) soit comme des personnes faisant partie de la famille de l’expérimentateur (autrui). Ensuite, nous avons évalué les jugements de « sentiment de savoir » (FOK), les performances de rappel et de reconnaissance, ainsi que les jugements de confiance (JOC) des participants pour le nom de chaque personne lorsque son visage était présenté. Nos résultats ont confirmé l’altération de la conscience de soi (c’est-à-dire l’anosognosie mesurée par l’AQD), l’altération du bénéfice mnésique pour les informations associées à soi, ainsi que l’altération des processus de monitoring lors de la récupération en mémoire (FOK et JOC) chez les patients MA. Néanmoins, une modification de l’interaction entre le soi et les processus de monitoring chez ces patients a été observée uniquement au niveau des sentiments de confiance pour des souvenirs erronés. Nous avons également observé que l’anosognosie des troubles comportementaux était significativement corrélée à la proportion de sentiments de confiance pour des reconnaissances erronées sur les items associés à soi. En conclusion, notre étude suggère que l’altération de la conscience des troubles comportementaux chez les patients MA pourrait être liée à un déficit de monitoring des souvenirs liés à soi. C’est-à-dire que la conscience altérée du dysfonctionnement au quotidien pourrait s’appuyer sur des souvenirs personnels déformés. [less ▲]

Detailed reference viewed: 76 (1 ULiège)
Full Text
Peer Reviewed
See detailResting-state test–retest reliability of a priori defined canonical networks over different preprocessing steps
Varikuti, Deepthi; Hoffstaedter, Felix; Genon, Sarah ULiege et al

in Brain Structure & Function (2017), 222(3), 1447-1468

Resting-state functional connectivity analysis has become a widely used method for the investigation of human brain connectivity and pathology. The measurement of neuronal activity by functional MRI ... [more ▼]

Resting-state functional connectivity analysis has become a widely used method for the investigation of human brain connectivity and pathology. The measurement of neuronal activity by functional MRI, however, is impeded by various nuisance signals that reduce the stability of functional connectivity. Several methods exist to address this predicament, but little consensus has yet been reached on the most appropriate approach. Given the crucial importance of reliability for the development of clinical applications, we here investigated the effect of various confound removal approaches on the test–retest reliability of functional connectivity estimates in two previously defined functional brain networks. Our results showed that gray matter masking improved the reliability of connectivity estimates, whereas denoising based on principal components analysis reduced it. We additionally observed that refraining from using any correction for global signals provided the best test–retest reliability, but failed to reproduce anti-correlations between what have been previously described as antagonistic networks. This suggests that improved reliability can come at the expense of potentially poorer biological validity. Consistent with this, we observed that reliability was proportional to the retained variance, which presumably included structured noise, such as reliable nuisance signals (for instance, noise induced by cardiac processes). We conclude that compromises are necessary between maximizing test–retest reliability and removing variance that may be attributable to non-neuronal sources. [less ▲]

Detailed reference viewed: 42 (1 ULiège)
Full Text
Peer Reviewed
See detailThe right dorsal premotor mosaic: organization, functions, and connectivity
Genon, Sarah ULiege; Li, Hai; Fan, Lingzhong et al

in Cerebral Cortex (2017), 27(3), 2095-2110

The right dorsal premotor cortex (PMd) of humans has been reported to be involved in a broad range of motor and cognitive functions. We explored the basis of this behavioral heterogeneity by performing a ... [more ▼]

The right dorsal premotor cortex (PMd) of humans has been reported to be involved in a broad range of motor and cognitive functions. We explored the basis of this behavioral heterogeneity by performing a connectivity-based parcellation using meta-analytic approach applied to PMd coactivations. We compared our CBP results to parcellations obtained through resting-state functional connectivity and probabilistic diffusion tractography,. Functional connectivity profiles and behavioral decoding of the resulting PMd subregions allowed characterizing their respective behavior profile. These procedures divided the right PMd into five distinct subregions that formed a cognitive-motor gradient along a rostro-caudal axis. In particular, we found (i) a rostral subregion functionally connected with prefrontal cortex, which likely supports high-level cognitive processes, such as working memory (ii) a central subregion showing a mixed behavioral profile and functional connectivity to parietal regions of the dorsal attention network, and (iii) a caudal subregion closely integrated with the motor system. Additionally, we found (iv) a dorsal subregion, preferentially related to hand movements and connected to both cognitive and motor regions, and (v) a ventral subregion, whose functional profile fits the concept of an eye-movement related field. In conclusion, right PMd may be considered as a functional mosaic formed by five subregions. [less ▲]

Detailed reference viewed: 129 (3 ULiège)
Full Text
See detailNeurobiologische Korrelate von exekutiver Kontrolle im alternden Gehirn
Overhage, Sina; Eickhoff, Simon; Jockwitz, Christiane et al

Poster (2017)

Detailed reference viewed: 43 (1 ULiège)
Full Text
Peer Reviewed
See detailRelating pessimistic memory predictions to Alzheimer’s disease brain structure
Genon, Sarah ULiege; Simon, Jessica ULiege; Bahri, Mohamed Ali ULiege et al

in Cortex : A Journal Devoted to the Study of the Nervous System & Behavior (2016), 85

Patients with Alzheimer’s disease (AD) show impairment of episodic memory and related metacognitive processes. The present study examined subjective metacognitive judgments preceding objective memory ... [more ▼]

Patients with Alzheimer’s disease (AD) show impairment of episodic memory and related metacognitive processes. The present study examined subjective metacognitive judgments preceding objective memory retrieval and investigated the neural correlates of pessimistic predictions for successfully retrieved memories in AD patients. AD patients and healthy older participants provided predictive judgements on their recognition performance before retrieval of famous (semantic) and recently learned (episodic) names. Correlations between grey matter volume (GMV) in T1 images and behavioural scores were examined with multivariate (PLS) and univariate (GLM) analyses in AD patients. AD patients showed a significant proportion of successful name recognition preceded by pessimistic prediction (Prediction_low_hits) in episodic memory. PLS revealed that behavioural pattern in AD patients was related with a mainly right lateralized pattern of GMV decrease including medial temporal lobe and posterior cingulate cortex, but also right ventrolateral prefrontal cortex (VLPFC). GLM further confirmed that pessimistic prediction negatively correlated with GMV in VLPFC. Thus, impaired monitoring processes (possibly influenced by inaccurate beliefs) allowing inferences about one’s own memory performance are primarily related to decrease GMV in VLPFC in AD patients. [less ▲]

Detailed reference viewed: 91 (14 ULiège)
Full Text
See detailMultimodal Connectivity-Based Parcellation of the Brain
Reuter, Niels; Plachti, Anna; Genon, Sarah ULiege et al

Poster (2016, October)

Detailed reference viewed: 35 (2 ULiège)
Full Text
See detailL’anosognosie dans la maladie d’Alzheimer: Soi, mémoire et jugement
Genon, Sarah ULiege

Speech/Talk (2016)

Detailed reference viewed: 35 (2 ULiège)
Full Text
Peer Reviewed
See detailDisrupted interaction between self and memory in patients with Alzheimer’s disease
Genon, Sarah ULiege; Salmon, Eric ULiege; Collette, Fabienne ULiege et al

Conference (2016, July)

In humans, self and memory processes interact as evidenced by the self reference (SRE) and self reference recollection effects (SRRE). However, in patients with Alzheimer’s disease (AD), this relationship ... [more ▼]

In humans, self and memory processes interact as evidenced by the self reference (SRE) and self reference recollection effects (SRRE). However, in patients with Alzheimer’s disease (AD), this relationship can be disrupted. This was evidenced by impaired SRE and SRRE in AD for recognition of adjectives previously judged for self-relevance, as well as recall of names of people previously linked to the self. For both materials, a qualitative impairment of the recollective experience for the self-related items was also observed in AD. A neuroimaging approach suggested that reduced SRE is related to decreased grey matter volume in the lateral prefrontal cortex (lPFC). Thus, retrieval of recent self-related memories is impaired in relation to altered high-order processes in lPFC in AD. [less ▲]

Detailed reference viewed: 89 (4 ULiège)
Full Text
See detailMapping cortical modules, their connectivity and functions
Genon, Sarah ULiege; Eickhoff, Simon

Conference (2016, April)

Detailed reference viewed: 25 (2 ULiège)