Biology subjects

Renoult, L.

Publications and source records attributed to Renoult, L..

6 recordsLinked to original sources

bioRxiv2026

The role of the Angular Gyrus in the Elaboration of Specific and Categoric Memories

This study investigated the role of the angular gyrus (AG) and its subregions in the elaboration of specific and categoric autobiographical memories (AMs). Using a cue-word fMRI paradigm, thirty-nine participants retrieved and elaborated on episodic (specific) and semantic (categoric) memories, rating the amount of detail of each recollection. Parametric analyses revealed that AG activity, particularly in posterior AG, was positively associated with the amount of detail retrieved, regardless of memory type. Specific memories elicited greater activation in right AG subregions compared to categoric memories. These findings support the AGs involvement in both episodic and semantic memory retrieval and suggest functional differentiation between its subregions.

neuroscience↗

bioRxiv2025

Testing for Interactions in Multivariate Data

Factorial designs are a mainstay of the scientific paradigm, allowing the effects of multiple experimental factors and their interactions to be efficiently studied within a single experiment. In brain imaging, however, multivariate data analyses commonly proceed using multivariate decoding and we argue that the standard "difference of accuracies" test is not a true test of interactions. To remedy this situation we propose an encoding method based on a Bayesian Multivariate Linear model which is ideally suited to the factorial analysis of such data. We show how it can be used to test for multivariate main effects and interactions using data from EEG studies of Reward Learning and Declarative Memory. This approach additionally allows for null hypotheses to be accepted and allows one to infer whether multivariate effects are driven by collections of univariate effects or voxel dependencies. We also propose that those wishing to pursue tests for interactions using decoding methods use an "accuracy of differences" test. Author summaryOur understanding of human brain function has been transformed by non-invasive imaging methods such as functional Magnetic Resonance Imaging and Electroencephalography. Statistical modelling has been central to this endeavour with foundational work employing a univariate encoding method in which multiple characteristics of participants behaviour (the stimuli they are exposed to, the decisions they make, the events they remember) are used to predict brain activity at a single point or voxel element (pixel/voxel) in a brain recording, and this process repeats for all voxels in an image. Subsequent work has used multivariate decoding methods which identify categorical behavioural variables from multivariate brain imaging data. Here we propose a new type of multivariate encoding approach in which a Bayesian multivariate linear model is used to predict multivariate image data from multivariate behavioural variables. This approach has three advantages (i) it can correctly test for interactions among experimental factors, (ii) we can quantify the experimental evidence in support of no experimental effects being present and (iii) we can make inferences about the nature of the multivariate effects.

neuroscience↗

bioRxiv2022

Cluster-Based Inference for Memory-Based Cognition

This paper proposes a model of hippocampal-based category learning using a cluster-based inference framework which produces two systems (i) an extendable cluster-based memory module (CMM) that provides representations of learning episodes with strong pattern separation, and supports online decision making during that learning, (ii) cluster-based task modules (CTMs) which consolidate clusters learnt by CMM to support higher-accuracy decision making in the mid-term. Learning in CMMs optimises the joint probability of stimuli and category labels, whereas learning in CTMs optimises the probability of categories given stimuli. The latter system learns from the former via a process of "cluster consolidation". We apply the model to data from a behavioral learning task and find that, as well as improving categorisation performance, cluster consolidation decreases recognition scores for old cues but increases them for novel cues. This model-based perspective explains forgetting and false memory effects as serving future categorisation performance. The paper also expresses a view that models of memorybased cognition should provide human-level performance on complex categorisation tasks, and do so with minimal labelled data. In working toward this goal we therefore compared the accuracy of CMM- and CTM-based decision making to standard Softmax Regression approaches on benchmark machine learning datasets. This produced mixed results. We found some significant improvements of CMM over Softmax Regression and of CTM over CMM. Overall, our framework reconciles complementary learning systems theory with more recent findings from cognitive neuroscience of generative replay and hippocampal-based generalisation.

neuroscience↗

bioRxiv2021

Expectation-Based Gist Facilitation: Rapid Scene Understanding and the Role of Top-Down Information

Scene meaning is processed rapidly, with gist extracted even when presentation duration spans a few dozen milliseconds. This has led some to suggest a primacy of bottom-up information. However, gist research has typically relied on showing successions of unrelated scene images, contrary to our everyday experience in which the world unfolds around us in a predictable manner. Thus, we investigated whether top-down information - in the form of observers predictions of an upcoming scene - facilitates gist processing. Within each trial, participants (N=336) experienced a series of images, organised to represent an approach to a destination (e.g., walking down a sidewalk), followed by a final target scene either congruous or incongruous with the expected destination (e.g., a store interior or a bedroom). Over a series of behavioural experiments, we found that: appropriate expectations facilitated gist processing; inappropriate expectations interfered with gist processing; the effect of congruency was driven by provision of contextual information rather than the thematic coherence of approach images, and; expectation-based facilitation was most apparent when destination duration was most curtailed. We then investigated the neural correlates of predictability on scene processing using ERP (N=26). Congruency-related differences were found in a putative scene-selective ERP component, related to integrating visual properties (P2), and in later components related to contextual integration including semantic and syntactic coherence (N400 and P600, respectively). Taken together, these results suggest that in real-world situations, top-down predictions of an upcoming scene influence even the earliest stages of its processing, affecting both the integration of visual properties and meaning.

neuroscience↗

bioRxiv2019

Encoding Variability: When Pattern Reactivation Does Not Benefit Context Memory

A growing body of evidence suggests that neural pattern reactivation supports successful memory formation across multiple study episodes. Previous studies investigating the beneficial effects of repeated encoding typically presented the same stimuli repeatedly under the same encoding task instructions. In contrast, repeating stimuli in different contexts is associated with superior item memory, but poorer memory for contextual features varying across repetitions. In the present functional magnetic-resonance imaging (fMRI) study, we predicted dissociable mechanisms to underlie the successful formation of context memory when the context in which stimuli are repeated is either held constant or varies at each stimulus presentation. Twenty participants studied names of famous people four times, either in the same task repeatedly, or in four different encoding tasks. This was followed by a surprise recognition memory test, including a source judgement about the encoding task. Behaviourally, different task encoding compared to same task encoding was associated with fewer correct context memory judgements but also better item memory, as reflected in fewer misses. Searchlight representational similarity analysis revealed fMRI pattern reactivation in the posterior cingulate cortex to be higher for correct compared to incorrect source memory judgements in the same task condition, with the opposite pattern being observed in the different task condition. It was concluded that higher levels of pattern reactivation in the posterior cingulate cortex index generalisation across context information, which in turn may improve item memory performance during encoding variability but at the cost of contextual features.

neuroscience↗

bioRxiv2018

A central component of the N1 event-related brain potential could index the early and automatic inhibition of the actions systematically activated by objects

Stimuli of the environment, like objects, systematically activate the actions they are associated to. These activations occur extremely fast. Nevertheless, behavioural data reveal that, in most cases, these activations are then automatically inhibited, around 100 ms after the occurrence of the stimulus. We thus tested whether this early inhibition could be indexed by a central component of the N1 event-related brain potential (ERP). To achieve that goal, we looked at whether this ERP component is greater in tasks that could increase the inhibition and in trials where reaction times happen to be long. The illumination of a real space bar of a keyboard out of the dark was used as a stimulus. To maximize the modulation of the inhibition, the task participants had to performed was manipulated across blocks. A look-only task and a count task were used to increase inhibition and an immediate press task was used to decrease it. ERPs of the two block-conditions where presses had to be prevented and where the largest central N1s were predicted were compared to those elicited in the press task, differentiating the ERPs to the third of the trials where presses were the slowest from the ERPs to the third of the trials with the fastest presses. Despite larger negativities due to motor potentials and despite greater attention likely in immediate press-trials, central N1s were found to be minimal for the fastest presses, intermediate for the slowest ones and maximal for the two no-press conditions. These results thus provide a strong support for the idea that the central N1 indexes an early and short lasting automatic inhibition of the actions systematically activated by objects. They also confirm that the strength of this automatic inhibition spontaneously fluctuates across trials and tasks. On the other hand, just before N1s, parietal P1s were found greater for fastest presses. They might thus index the initial activation of these actions. Finally, consistent with the idea that N300s index late inhibition processes, that occur preferentially when the task requires them, these ERPs were quasi absent for fast presses trials and much larger in the three other conditions.\n\nHighlightsEvent-related brain potentials (ERPs) elicited by a real object\n\nSmaller parietal P1s and greater central N1s for slowest than for fastest motor responses\n\nEven greater central N1s for tasks without such responses\n\nCentral N1s may index early inhibition of stimulus-activated actions\n\nN300s could index late inhibition of stimulus-activated actions

animal behavior and cognition↗