Maximilien Chaumon

Institut du cerveau · CENIR

Brain regions that process affect are strongly connected with visual regions, but the functional consequences of this structural organization have been relatively unexplored. How does the momentary affect of an observer influence perception? We induced either pleasant or unpleasant affect in participants and then recorded their neural activity usin...

The brain exhibits organized fluctuations of neural activity, even in the absence of tasks or sensory input. A prominent type of such spontaneous activity is the alpha rhythm, which influences perception and interacts with other ongoing neural activity. It is currently hypothesized that states of decreased prestimulus α oscillations indicate enhanc...

Significance statement: Spontaneous fluctuations of brain activity explain why a faint sensory stimulus is sometimes perceived and sometimes not. The prevailing view is that heightened neural excitability, indexed by decreased alpha oscillations, promotes better perceptual performance. Here, we provide evidence that heightened neural excitability...

Electroencephalographic data are easily contaminated by signals of non-neural origin. Independent component analysis (ICA) can help correct EEG data for such artifacts. Artifact independent components (ICs) can be identified by experts via visual inspection. But artifact features are sometimes ambiguous or difficult to notice, and even experts may...

In this study, we used EEG to investigate how visual stimulus dynamics (i.e. flicker) affect the mechanisms of duration perception. Previous studies have demonstrated that flickering visual stimuli are judged longer than equally long non-flickering stimuli. We tested whether this effect of flicker on duration judgments is mediated by changes in tem...

The cerebral cortex responds to stimuli of a wide range of intensities. Previous studies have demonstrated that undetectably weak somatosensory stimuli cause a functional deactivation or inhibition in somatosensory cortex. In the present study, we tested whether invisible visual stimuli lead to similar responses, indicated by an increase in EEG alp...

The ongoing state of the brain radically affects how it processes sensory information. How does this ongoing brain activity interact with the processing of external stimuli? Spontaneous oscillations in the alpha range are thought to inhibit sensory processing, but little is known about the psychophysical mechanisms of this inhibition. We recorded o...

The passage of time is inseparably linked to any subjective experience, but time cannot be perceived itself. Since humans lack a sensory organ for time, time perception is constructed based on the percepts of the existent senses, such as lights or tones. Biases in these percepts can lead to biases in temporal perception, which explains why subjecti...

Predicting upcoming events from incomplete information is an essential brain function. The orbitofrontal cortex (OFC) plays a critical role in this process by facilitating recognition of sensory inputs via predictive feedback to sensory cortices. In the visual domain, the OFC is engaged by low spatial frequency (LSF) and magnocellular-biased inputs...

Ongoing brain oscillations in the alpha frequency range (8-12 Hz) strongly affect perception and neuronal responses to incoming visual stimuli. However, the nature of their effect on perception remains largely unknown. Mechanisms of cognitive processes that affect perception and neuronal responses – such as attention or perceptual learning – have b...

Semantic processing of verbal and visual stimuli has been investigated in semantic violation or semantic priming paradigms in which a stimulus is either related or unrelated to a previously established semantic context. A hallmark of semantic priming is the N400 event-related potential (ERP)--a deflection of the ERP that is more negative for semant...

Objects are more easily recognized in their typical context. However, is contextual information activated early enough to facilitate the perception of individual objects, or is contextual facilitation caused by postperceptual mechanisms? To elucidate this issue, we first need to study the temporal dynamics and neural interactions associated with co...

Memory and perception are two tightly interrelated cognitive processes, but the neural level of their interaction remains a matter of debate. Proponents of a late interaction emphasize feedback memory effects on visual processing, whereas others suggest that feed forward processing is affected by memory. In the visual domain, unconscious memory for...

Oscillatory synchrony in the gamma band (30-120 Hz) has been involved in various cognitive functions including conscious perception and learning. Explicit memory encoding, in particular, relies on enhanced gamma oscillations. Does this finding extend to unconscious memory encoding? Can we dissociate gamma oscillations related to unconscious learnin...

In mammals, the visual field is split along the midline, each hemisphere representing the contralateral hemifield. We determined that, in the ferret, an 8- to 10-deg-wide strip of visual field near the midline is represented in both hemispheres. Bright squares (1.5 deg) were flashed at different azimuths within the central 20 deg of the visual fiel...

Searching for an object in a cluttered environment takes advantage of different cues, explicit attentional cues, such as arrows, and visual cues, such as saliency, but also memory. Behavioral studies manipulating the spatial relationships between context and target in visual search suggest that the memory of context-target associations could be ret...

Neural oscillatory synchrony could implement grouping processes, act as an attentional filter, or foster the storage of information in short-term memory. Do these findings indicate that oscillatory synchrony is an unspecific epiphenomenon occurring in any demanding task, or that oscillatory synchrony is a fundamental mechanism involved whenever neu...

Le contexte guide la perception de manière inconsciente. En vision, il est utilisé pour faciliter la reconnaissance et la recherche d’objets. Nous avons élaboré un protocole expérimental nouveau pour étudier l’influence du contexte sur la recherche visuelle en magnéto-encéphalographie (MEG). Une étude chez des sujets sains nous a permis d’observer...