Pierre-Marie Baudonnière

Evidence of a visual-to-auditory cross-modal sensory gating phenomenon as reflected by the human P50 event-related brain potential modulation

We investigated the existence of a cross-modal sensory gating reflected by the modulation of an early electrophysiological index, the P50 component. We analyzed event-related brain potentials elicited by audiovisual speech stimuli manipulated along two dimensions: congruency and discriminability. The results showed that the P50 was attenuated when visual and auditory speech information were redundant (i.e. congruent), in comparison with this same event-related potential component elicited with discrepant audiovisual dubbing. When hard to discriminate, however, bimodal incongruent speech stimuli elicited a similar pattern of P50 attenuation. We concluded to the existence of a visual-to-auditory cross-modal sensory gating phenomenon. These results corroborate previous findings revealing a very early audiovisual interaction during speech perception. Finally, we postulated that the sensory gating system included a cross-modal dimension.

COGNITIVE EFFECTS ON VISUALLY INDUCED BODY MOTION IN CHILDREN

Cognitive effects on linear sagittal vection in children were investigated. Forty children (7 and 11 years old) were exposed to a bilateral backward optical flow in a single physical condition (seated in a stationary armchair) but in two contrasted cognitive conditions. In one cognitive condition, the children were precisely informed that the armchair could move. In the other, they were informed that the armchair could not move. In each age group, half the children were assigned to one cognitive condition, the other half to the other condition. The results indicate that knowledge about the plausibility of a physical displacement does not affect the probability of obtaining vection. However, at both ages, the latencies for reporting vection were shorter when the physical displacement was known to be possible than when it was known to be impossible. The present results indicate that exclusively cognitive factors do not affect vection occurrence but can modulate latencies for reporting vection.

Feedback in Hypothesis Testing: An ERP Study

We used event-related potentials (ERPs) to probe the effects of feedback in a hypothesis testing (HT) paradigm. Thirteen college students serially tested hypotheses concerning a hidden rule by judging its presence or absence in triplets of digits and revised them on the basis of an exogenous performance feedback. ERPs time-locked to performance feedback were then examined. The results showed differences between responses to positive and negative feedback at all cortical sites. Negative feedback, indicating incorrect performance, was associated to a negative deflection preceding a P300-like wave. Spatiotemporal principal component analysis (PCA) showed the interplay between early frontal components and later central and posterior ones. Lateralization of activity was selectively detectable at frontal sites, with a left frontal dominance for both positive and negative feedback. These results are discussed in terms of a proposed computational model of trial-to-trial feedback in HT in which the cognitive and emotive aspects of feedback are explicitly linked to putative mediating brain mechanisms. The properties of different feedback types and feedback-related deficits in depression are also discussed.

Development of Communicative Competencies in Early Childhood: A Model and Results

During the past 5 years, investigations of social development at the Laboratoire de Psychobiologie de l’Enfant in Paris have centered on the ontogeny of communicative competence during early childhood. This general theme has been subdivided into a number of more specific topics that have become the particular interest of different research groups at the laboratory. Children’s capacities to initiate socially directed behaviors, to respond to actions that have been directed to themselves, to synchronize these social exchanges, and to successfully transmit messages to social partners emerge progressively from birth during the course of social interaction with familiar others.

Feedback modulates gamma oscillations in a hypothesis testing paradigm

We analyzed the time-varying modulation of gamma (>30 Hz) electroencephalographic (EEG) activity exerted by positive and negative feedback in a hypothesis testing paradigm. Ten college students serially tested hypotheses concerning a hidden rule by judging its presence or absence in triplets of digits and revised them on the basis of an exogenous performance feedback. The EEG signal was convolved with a family of complex wavelets and brain potentials were extracted in the gamma range. Feedback-related modulations were found as early as 100 ms after feedback onset, as well as in the 300-600 ms time-window. The results were discussed in terms of functional and neurophysiological models of feedback.