Biomedical subjects

Beatrice de Gelder

Publications and source records attributed to Beatrice de Gelder.

27 records · Page 2Linked to original sources

PubMed2003

Seeing fearful body expressions activates the fusiform cortex and amygdala.

Darwin's evolutionary approach to organisms' emotional states attributes a prominent role to expressions of emotion in whole-body actions. Researchers in social psychology [1,2] and human development [3] have long emphasized the fact that emotional states are expressed through body movement, but cognitive neuroscientists have almost exclusively considered isolated facial expressions (for review, see [4]). Here we used high-field fMRI to determine the underlying neural mechanisms of perception of body expression of emotion. Subjects were presented with short blocks of body expressions of fear alternating with short blocks of emotionally neutral meaningful body gestures. All images had internal facial features blurred out to avoid confounds due to a face or facial expression. We show that exposure to body expressions of fear, as opposed to neutral body postures, activates the fusiform gyrus and the amygdala. The fact that these two areas have previously been associated with the processing of faces and facial expressions [5-8] suggests synergies between facial and body-action expressions of emotion. Our findings open a new area of investigation of the role of body expressions of emotion in adaptive behavior as well as the relation between processes of emotion recognition in the face and in the body.

Amygdala↗

PubMed2003

A modulatory role for facial expressions in prosopagnosia.

Brain-damaged patients experience difficulties in recognizing a face (prosopagnosics), but they can still recognize its expression. The dissociation between these two face-related skills has served as a keystone of models of face processing. We now report that the presence of a facial expression can influence face identification. For normal viewers, the presence of a facial expression influences performance negatively, whereas for prosopagnosic patients, it improves performance dramatically. Accordingly, although prosopagnosic patients show a failure to process the facial configuration in the interest of face identification, that ability returns when the face shows an emotional expression. Accompanying brain-imaging results indicate activation in brain areas (amygdala, superior temporal sulcus, parietal cortex) outside the occipitotemporal areas normally activated for face identification and lesioned in these patients. This finding suggests a modulatory role of these areas in face identification that is independent of occipitotemporal face areas.

Adult↗

PubMed2003

Audio-visual integration in schizophrenia.

Integration of information provided simultaneously by audition and vision was studied in a group of 18 schizophrenic patients. They were compared to a control group, consisting of 12 normal adults of comparable age and education. By administering two tasks, each focusing on one aspect of audio-visual integration, the study could differentiate between a spatial integration deficit and a speech-based integration deficit. Experiment 1 studied audio-visual interactions in the spatial localisation of sounds. Experiment 2 investigated integration of auditory and visual speech. The schizophrenic group performed as the control group on the sound localisation task, but in the audio-visual speech task, there was an impairment in lipreading as well as a smaller impact of lipreading on auditory speech information. Combined with findings about functional and neuro-anatomical specificity of intersensory integration, the data suggest that there is an integration deficit in the schizophrenic group that is related to the processing of phonetic information.

Adult↗

PubMed2003

Face processing in adolescents with autistic disorder: the inversion and composite effects.

Two experiments with upright and inverted face and object images were carried out to investigate whether face processing in autism is more feature-based than in individuals with typical development. Participants were 17 high-ability adolescents with autistic disorder (16-24 years), 24 typically developing children (9-10 years) and 16 adults (18-33 years). In Experiment 1, a normal inversion effect was found for the adolescents with autism in a standard face recognition paradigm with reduced memory demands, except for a subgroup with low social intelligence who were not better in recognizing upright relative to inverted photographs of faces. In Experiment 2, the group with autism did not show the composite effect like the adult group did: they recognized face halves as well in aligned composite faces as in non-aligned composite faces. The results on the inversion task suggest that most adolescents with autism form a normal configuration-based face representation, but the absence of the composite effect indicates that they are less prone to use the contextual information of the face in a visual-search task.

Adolescent↗

PubMed2003

Visual motion influences the contingent auditory motion aftereffect.

In this study, we show that the contingent auditory motion aftereffect is strongly influenced by visual motion information. During an induction phase, participants listened to rightward-moving sounds with falling pitch alternated with leftward-moving sounds with rising pitch (or vice versa). Auditory aftereffects (i.e., a shift in the psychometric function for unimodal auditory motion perception) were bigger when a visual stimulus moved in the same direction as the sound than when no visual stimulus was presented. When the visual stimulus moved in the opposite direction, aftereffects were reversed and thus became contingent upon visual motion. When visual motion was combined with a stationary sound, no aftereffect was observed. These findings indicate that there are strong perceptual links between the visual and auditory motion-processing systems.

Attention↗

PubMed2002

Semantic factors influence multisensory pairing: a transcranial magnetic stimulation study.

It is traditionally assumed that temporal and spatial factors determine whether information provided by different sensory modalities is combined in a single percept. However, neuropsychological reports of selective damage to audio-visual integration and recent neurophysiological results suggest that semantic factors related to the content of the stimuli could also play a role. As a means of extending evidence provided by neuropsychological dissociations we set up a direct comparison of two kinds of audio-visual pairs with different semantic properties and used transcranial magnetic stimulation (TMS). We investigated the selective impact of TMS on two kinds of audio-visual pairings presented under identical spatio-temporal conditions (face-voice and tone-shape pairings). Our results show that TMS applied over the left posterior parietal cortex at 200 ms disrupted audio-visual integration for the tone-shape pairings but not for the face-voice ones. Our data are consistent with neuropsychological findings and indicate that besides the well-known dimensions of spatial and temporal contiguity, content is an important determinant of audio-visual integration. Our study also illustrates the usefulness of TMS for addressing the role of semantic factors in multi-sensory perception

Acoustic Stimulation↗

PubMed2002

Fear recognition in the voice is modulated by unconsciously recognized facial expressions but not by unconsciously recognized affective pictures.

Multisensory integration is a powerful mechanism for increasing adaptive responses, as illustrated by binding of fear expressed in a face with fear present in a voice. To understand the role of awareness in intersensory integration of affective information we studied multisensory integration under conditions of conscious and nonconscious processing of the visual component of an audiovisual stimulus pair. Auditory-event-related potentials were measured in two patients (GY and DB) who were unable to perceive visual stimuli consciously because of striate cortex damage. To explore the role of conscious vision of audiovisual pairing, we also compared audiovisual integration in either naturalistic pairings (a facial expression paired with an emotional voice) or semantic pairings (an emotional picture paired with the same voice). We studied the hypothesis that semantic pairings, unlike naturalistic pairings, might require mediation by intact visual cortex and possibly by feedback to primary cortex from higher cognitive processes. Our results indicate that presenting incongruent visual affective information together with the voice translates as an amplitude decrease of auditory-event-related potentials. This effect obtains for both naturalistic and semantic pairings in the intact field, but is restricted to the naturalistic pairings in the blind field.

Acoustic Stimulation↗

PubMed2002

Neural basis of prosopagnosia: an fMRI study.

Brain imaging research has identified at least two regions in human extrastriate cortex responding selectively to faces. One of these is located in the mid-fusiform gyrus (FFA), the other in the inferior occipital gyrus (IOG). We studied activation of these areas using fMRI in three individuals with severely impaired face recognition (one pure developmental and two childhood prosopagnosics). None of the subjects showed the normal pattern of higher fMRI activity to faces than to objects in the FFA and IOG or elsewhere. Moreover, in two of the patients, faces and objects produced similar activations in the regions corresponding to where the FFA and IOG are found in normal subjects. Our study casts light on the important role of FFA and IOG in the network of areas involved in face recognition, and indicates limits of brain plasticity.

Adult↗

PubMed2002

Facial expressions modulate the time course of long latency auditory brain potentials.

Long latency auditory brain potentials were recorded while subjects listened to bi-syllabic words spoken with an emotional expression and concurrently viewed congruent or incongruent facial expressions. Analysis of the auditory waveforms suggests the existence of a positive deflection around 240 ms post-stimulus with a clear posterior topography (the P2b component). This potential is subsequent upon the modality-specific auditory N1-P2 components and precedes the amodal N2-P3 complex. Congruent face-voice trials elicited an earlier P2b component than incongruent trials suggesting that auditory processing is delayed in the presence of an incongruent facial context. These electrophysiological results are consistent with previous behavioural studies showing an acceleration of reaction times for rating voice expressions that are part of congruent bimodal stimulus pairs. A source localisation analysis performed on the scalp EEG during the time-window corresponding to the P2b component disclosed a single dipole solution in the anterior cingulate cortex.

Acoustic Stimulation↗