Evidence for distinct roles of posterior superior temporal sulcus and inferior frontal areas in audiovisual action recognition.
Georg F Meyer, Sophie Wuerger
Poster
Time: 2009-06-30 09:00 AM – 10:30 AM
Last modified: 2009-06-04
Abstract
INTRODUCTION: We previously reported significant interactions in BOLD response for congruent and incongruent semantic audiovisual action sequences (whole-body actions and speech actions) in bilateral pSTS (BA 22), left SMA (BA6), left IFG (BA44) and IPL (BA 40). We found strong activation but no interaction in bilateral premotor areas (BA 6) or in conditions where meaningful actions were paired with meaningless stimuli.
Here we present the results from a high density EEG study that complement the fMRI data and suggests distinct roles for pSTS and left IFG in the integration of bimodal action sequences.
METHODS: 11 subjects (7 female, age range 20-43 yrs, all right handed) were presented with audio-visual displays of whole-body actions and speech syllables. The stimuli could be congruent or incongruent (body motion in one modality, speech in the other). Subjects were asked to respond to stimulus repetition in one or both modalities (10% of stimuli).
EEG data was recorded with a 129 channel dense sensor net (Electrical Geodesics Inc, Eugene OR, USA). Ocular artefact removal and statistical channel and epoch selection (SCADS, Junghöfer et al., Psychophysiol, 2000) was used to obtain artefact free epochs. The pooled ERPs for the two conditions were compared to identify areas and times of significant difference. Dipoles were fitted (BESA, MEGIS Software GmbH, Munich) to associate the time windows of interference with activity in source locations.
RESULTS: Responses to congruent stimuli are larger between 250ms and 350ms after stimulus onset in left frontotemporal electrodes. The response to incongruent stimuli is larger in left inferior frontal electrode positions from 600ms after stimulus onset. The difference around 300ms can be explained by a modulation of sources in the superior temporal area while the response difference after 600ms is consistent with an increase of activity in the left IFG.
CONCLUSIONS: Our results are consistent with a model that postulates early recognition of congruent audiovisual actions in the pSTS, perhaps as a sensory memory buffer, and a role of the IFG, perhaps in a generative capacity, in reconciling incongruent signals.
Here we present the results from a high density EEG study that complement the fMRI data and suggests distinct roles for pSTS and left IFG in the integration of bimodal action sequences.
METHODS: 11 subjects (7 female, age range 20-43 yrs, all right handed) were presented with audio-visual displays of whole-body actions and speech syllables. The stimuli could be congruent or incongruent (body motion in one modality, speech in the other). Subjects were asked to respond to stimulus repetition in one or both modalities (10% of stimuli).
EEG data was recorded with a 129 channel dense sensor net (Electrical Geodesics Inc, Eugene OR, USA). Ocular artefact removal and statistical channel and epoch selection (SCADS, Junghöfer et al., Psychophysiol, 2000) was used to obtain artefact free epochs. The pooled ERPs for the two conditions were compared to identify areas and times of significant difference. Dipoles were fitted (BESA, MEGIS Software GmbH, Munich) to associate the time windows of interference with activity in source locations.
RESULTS: Responses to congruent stimuli are larger between 250ms and 350ms after stimulus onset in left frontotemporal electrodes. The response to incongruent stimuli is larger in left inferior frontal electrode positions from 600ms after stimulus onset. The difference around 300ms can be explained by a modulation of sources in the superior temporal area while the response difference after 600ms is consistent with an increase of activity in the left IFG.
CONCLUSIONS: Our results are consistent with a model that postulates early recognition of congruent audiovisual actions in the pSTS, perhaps as a sensory memory buffer, and a role of the IFG, perhaps in a generative capacity, in reconciling incongruent signals.