Le 23 septembre
Organisé par Marion Vincent, IGR Université de Lille – SCALab, FR-SCV
Séminaires le 23/09 sur le site FR-SCV et en visio de 13 à 15h30
Boris Cheval (Univ. Genève)
Aliette Lochy (Univ. Luxembourg)
Milena Dzhelyova (UC Louvain)
Boris Cheval (Univ. Genève) – Effort Minimization in Physical Activity
While the automatic attraction to effort minimization has been widely evidenced in multiple fields, its potential role in explaining the pandemic of physical inactivity has been overlooked. In this presentation, I will first introduce the Theory of Effort Minimization in Physical Activity (TEMPA), a theory that aims to provide a more accurate understanding of the neuropsychological determinants of movement-based behaviors. Then, I will present behavioral, psychophysiological, and large-scale longitudinal data supporting the TEMPA. Finally, I will discuss the implications in terms of interventions aiming to tackle the pandemic of physical inactivity.
14:30-15:30 Dans le cadre du workshop Steady-state
Aliette Lochy (Univ. Luxembourg) – Developing cortical specialization for visual word recognition: EEG studies with fast periodic visual stimulation
A crucial question in reading development is to understand how and when emerges the specialization of neural circuits for reading, how it changes with schooling, and if teaching methods impact brain networks for letters and words. To examine this issue, we used fast periodic visual stimulation (FPVS) EEG in a series of studies in young children investigating selective visual responses to letters and words. Base stimuli are presented at a fast rate (e.g., pseudofonts at 6Hz), and a categorical change is introduced periodically (e.g., words every 5 items, at 1.2Hz). If the visual system discriminates between the two categories, a response is measurable at the frequency of the categorical change. In a few minutes of recordings only, our results show that letter-selective responses are left-lateralized in posterior regions even in 5 years-old preschoolers with only rudimentary letter knowledge. Furthermore, (pre)reading abilities correlate with letter-selective responses. In a longitudinal study following young beginning readers during early formal reading education (from the 1st to the 2nd grade), an increase in letter-selective response as well as an increase in left lateralization was found, with no yet lexical responses. As reading is only acquired via instruction, it is crucial to assess the influence of different teaching methods on the developing brain responses for reading. We recently investigated in French the impact of the global method, which aims at developing mappings between whole visual word forms and corresponding lexical items. We found that poor readers, who knew only a few letters-sound mappings, were more heavily impacted than good readers, revealing engagement of the right hemisphere when processing words globally. This result showed that teaching method may impact the neural networks for reading, especially in poor readers who rely on alternative strategies like rote-visual recognition, rather than on the left hemisphere mechanisms necessary for developing the reading network. Our findings support an early emergence of ventral occipito-temporal cortex specialization for visual recognition of letters, and point to the sensitivity of FPVS-EEG approach to track its development and to assess the impact of reading interventions or educational practices.
Milena Dzhelyova (UC Louvain) – Decoding Human Facial Expression
The past four decades have seen a large amount of scientific research carried out to understand how the human central nervous system decodes facial expressions of emotion. However, valid spatio-temporal markers that uniquely define the processing of each of the different facial expressions have been extremely difficult to obtain. To address these issues, a high-density electroencephalogram (EEG) was recorded in 18 participants presented with a neutral-expression face at a rate of 5.88 Hz (F) for 80 s. Every five faces, the face changed expression to fear, disgust or happiness (different stimulation sequences). The resulting 1.18 Hz (F/5) EEG response and its harmonics objectively indexed detection of a brief change of facial expression. This response was recorded in every participant in a few minutes but was largely reduced for inverted faces, indicating that it reflects high-level processes. Although this response focused on occipito-temporal sites, different expression changes evoked reliably distinct topographical maps, pointing to partly distinct neural generators. Following this, I examined the extent to which the 6 basic human facial expressions perceptually differ from one another. While fearful faces presented as repeated stimuli led to the smallest deviant responses from all other basic expressions, deviant fearful faces were well discriminated overall, and to a larger extent than expressions of sadness and anger. Expressions of happiness do not differ quantitatively as much in EEG as for behavioral subjective judgments, suggesting that the clear dissociation between happy and other expressions typically observed in behavioral studies reflect higher-order processes. However, this expression differs from all others in terms of scalp topography, pointing to a qualitative difference when switching from a negative to a positive expression compared to switching within negative expressions. Despite these differences, we found very tight relationship between the strength of the neural discrimination response and behavioral similarity among the expression. These results were extended with more subtle expressions and in (a)typical children revealing the potential of the method to understanding facial expression discrimination in developmental, intercultural, and clinical populations.