Biology subjects

Rossion, B.

Publications and source records attributed to Rossion, B..

8 recordsLinked to original sources

bioRxiv2018

Teaching methods shape neural tuning to visual words in beginning readers

The impact of global vs. phonics teaching methods for reading on the emergence of left hemisphere neural specialization for word recognition is unknown in children. We tested 42 first graders behaviorally and with electroencephalography with Fast Periodic Visual Stimulation to measure selective neural responses to letter strings. Letter strings were inserted periodically (1/5) in pseudofonts in 40sec sequences displayed at 6Hz and were either words globally taught at school, eliciting visual whole-word form recognition (global method), or control words/pseudowords eliciting grapheme-phoneme mappings (phonic method). Selective responses (F/5, 1.2Hz) were left lateralized for control stimuli but bilateral for globally taught words, especially in poor readers. These results show that global method instruction induces activation in the right hemisphere, involved in holistic processing and visual object recognition, rather than in the specialized left hemisphere for reading. Poor readers, given their difficulties in automatizing grapheme-phoneme mappings, mostly rely on this alternative inadequate strategy.

neuroscience↗

bioRxiv2018

Immediate stimulus repetition abolishes stimulus expectation and surprise effects in fast periodic visual oddball designs

Oddball designs are widely used to investigate the sensitivity of the visual system to statistical regularities in sensory environments. However, the underlying mechanisms that give rise to visual mismatch responses remain unknown. Much research has focused on identifying separable, additive effects of stimulus repetition and stimulus appearance probability (expectation/surprise) but findings from non-oddball designs indicate that these effects also interact. We adapted the fast periodic visual stimulation (FPVS) unfamiliar face identity oddball design (Liu-Shuang et al., 2014) to test for both additive and interactive effects of stimulus repetition and stimulus expectation. In two experiments, a given face identity was presented at a 6 Hz periodic rate; a different identity face (the oddball) appeared as every 7th image in the sequence (i.e., at 0.857 Hz). Electroencephalographic (EEG) activity was recorded during these stimulation sequences. In Experiment 1, we tested for surprise responses evoked by unexpected face image repetitions by replacing 10% of the commonly-presented oddball faces with exact repetitions of the base rate face identity image. In Experiment 2, immediately repeated or unrepeated face identity oddballs were presented in high and low presentation probability contexts (i.e., expected or surprising), allowing assessment of expectation effects on responses to both repeated and unrepeated stimuli. Across both experiments objective (i.e., frequency-locked) visual mismatch responses driven by stimulus expectation were only found for oddball faces of a different identity to base rate faces (i.e., unrepeated identity oddballs). Our results show that immediate stimulus repetition (i.e., repetition suppression) can reduce or abolish expectation effects as indexed by EEG responses in visual oddball designs.\n\nHighlights- We studied visual mismatch responses with a fast periodic oddball design\n- Our design cleanly separates immediate stimulus repetition and expectation effects\n- Stimulus expectation effects were only present for unrepeated stimuli\n- Immediate stimulus repetition reduced EEG expectation effects

neuroscience↗

bioRxiv2018

The impact of stimulus size and orientation on individual face decoding in monkey face-selective cortex.

Face-selective neurons in the monkey temporal cortex discharge at different rates in response to pictures of different faces. Here we tested whether the population response of neurons in the face-selective area ML (located in the middle Superior Temporal Sulcus) tolerates two affine transformations; one, picture-plane inversion, known to have a deleterious impact on the average response of face-selective neurons and the other, stimulus size, thought to have little or no impact on face-selective neurons. We recorded the response of 57 ML neurons in two monkeys. Face stimuli were presented at two sizes (10 and 5 degrees of visual angle) and two orientations (upright and inverted). The results indicate that different faces elicited distinct patterns of activity across ML neurons that were tolerant of changes in size. However, the results of the orientation manipulation were mixed; despite observing a reduced response to inverted faces, classifier performance was above chance for both upright and inverted faces and the classification score did not differ significantly for inverted and upright faces. We conclude that population responses in area ML to different faces are dependent on stimulus orientation but are more tolerant to changes in stimulus size.

neuroscience↗

bioRxiv2017

Functional selectivity for face processing in the temporal voice area of early deaf individuals

Brain systems supporting face and voice processing both contribute to the extraction of important information for social interaction (e.g., person identity). How does the brain reorganize when one of these channels is absent? Here we explore this question by combining behavioral and multimodal neuroimaging measures (magneto-encephalography and functional imaging) in a group of early deaf humans. We show enhanced selective neural response for faces and for individual face coding in a specific region of the auditory cortex that is typically specialized for voice perception in hearing individuals. In this region, selectivity to face signals emerges early in the visual processing hierarchy, shortly following typical face-selective responses in the ventral visual pathway. Functional and effective connectivity analyses suggest reorganization in long-range connections from early visual areas to the face-selective temporal area in individuals with early and profound deafness. Altogether, these observations demonstrate that regions that typically specialize for voice processing in the hearing brain preferentially reorganize for face processing in born deaf people. Our results support the idea that cross-modal plasticity in case of early sensory deprivation relates to the original functional specialization of the reorganized brain regions.

neuroscience↗

bioRxiv2017

A Face Identity Hallucination (Palinopsia) Generated By Intracerebral Stimulation Of The Face-Selective Right Lateral Fusiform Cortex

We report the case of a patient (MB, young female human subject) who systematically experiences confusion between perceived facial identities when electrically stimulated inside the lateral section of the right fusiform gyrus. In the presence of a face stimulus (an experimenter or a photograph), intracerebral electrical stimulation in this region generates a perceptual hallucination of an individual facial part integrated within the whole perceived face, i.e. facial palinopsia. In the presence of a distracting stimulus (visual scene or object picture), the patient also experiences an individual face percept superimposed on the non-face stimulus. The stimulation site evoking this category-selective transient palinopsia is localized in a region showing highly selective responses to faces both with functional magnetic resonance imaging (\"Fusiform Face Area\", \"FFA\") and intracerebral electrophysiological recordings during fast periodic visual stimulation (FPVS). Importantly, the largest electrophysiological response to fast periodic changes of facial identity is also found at this location. Altogether, these observations suggest that a local face-selective region of the right lateral fusiform gyrus suffices to generate a vivid percept of an individual face, supporting the active role of this region in individual face representation.

neuroscience↗

bioRxiv2017

Fast Periodic Stimulation (FPS): A Highly Effective Approach In fMRI Brain Mapping

Functional magnetic resonance imaging (fMRI) is a major technique for human brain mapping. We present a Fast Periodic Stimulation (FPS) fMRI approach, demonstrating its high effectiveness in defining category-selective brain regions. Observers see a dynamic stream of widely variable natural object images alternating at a fast rate (6 images/sec). Every 9 seconds, a short burst of variable face images contrasting with objects in pairs induces an objective 0.111 Hz face-selective neural response in the ventral occipito-temporal cortex and beyond. A model-free Fourier analysis achieves a two-fold increase in signal-to-noise ratio compared to a conventional block-design approach with identical stimuli. Periodicity of category contrast and random variability among images minimize low-level visual confounds while preserving naturalness of the stimuli, leading to the highest values (80-90%) of test-retest reliability yet reported in this area of research. FPS-fMRI opens a new avenue for understanding brain function with low temporal resolution methods.\n\nHighlightsFPS-fMRI achieves a two-fold increase in peak SNR over conventional approach\n\nFPS-fMRI reveals comprehensive extended face-selective areas including ATL\n\nFPS-fMRI achieves high specificity by minimizing influence of low-level visual cues\n\nFPS-fMRI achieves very high test-retest reliability (80%-90%) in spatial activation map\n\neTOC BlurbIn Brief\n\nGao et al. present a novel FPS-fMRI approach, which achieves a two-fold increase in peak signal-to-noise ratio in defining the neural basis of visual categorization while preserving ecological validity, minimizing low-level visual confounds and reaching very high (80%-90%) test-retest reliability.

neuroscience↗

bioRxiv2017

The Non-Linear Development Of The Right Hemispheric Specialization For Human Face Perception

The developmental origins of human adults right hemispheric specialization for face perception remain unclear. On the one hand, infant studies have generally shown a right hemispheric advantage for face perception. On the other hand, the adult right hemispheric lateralization for face perception is thought to slowly emerge during childhood, due to reading acquisition, which increases left lateralized posterior responses to competing written material (i.e., visual letters and words). Since methodological approaches used in infant and children usually differ, resolving this issue has been difficult. Here we tested 5-year-old preschoolers varying in their level of visual letter knowledge with the same fast periodic visual stimulation (FPVS) paradigm leading to strongly right lateralized electrophysiological occipito-temporal face-selective responses in 4- to 6-month-old infants (de Heering & Rossion, 2015). Childrens face-selective response was much larger and more complex than in infants, but did not differ across hemispheres. However, there was a small positive correlation between preschoolers letter knowledge and their right hemispheric specialization for faces. These observations suggest that several factors contribute to the adult right hemispheric lateralization for faces, and point to the value of FPVS coupled with electroencephalography to assess specialized face perception processes throughout development with the same methodology.

neuroscience↗

bioRxiv2017

Category-Selective Human Brain Processes Elicited In Fast Periodic Visual Stimulation Streams Are Immune To Temporal Predictability

Recording direct neural activity when periodically inserting exemplars of a particular category in a rapid visual stream of other objects offers an objective and efficient way to quantify perceptual categorization and characterize its spatiotemporal dynamics. However, since periodicity entails predictability, perceptual categorization processes identified within this framework may be partly generated or modulated by temporal expectations. Here we present a stringent test of the hypothesis that temporal predictability generates or modulates category-selective neural processes. In Experiment 1, we compare neurophysiological responses to periodic and nonperiodic (i.e., unpredictable) variable face stimuli in a fast (12 Hz) visual stream of nonface objects. In Experiment 2, we assess potential responses to rare (10%) omissions of periodic face events (i.e., violations of periodicity) in the same fast visual stream. Overall, our observations indicate that long duration category(face)-selective processes elicited in a fast periodic stream of visual objects are immune to temporal predictability. These observations do not support a predictive coding framework interpretation of category-change detection in the human brain and have important implications for understanding human perceptual categorization in a rapidly changing (i.e., dynamic) visual scene.

neuroscience↗