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Decoding social signals in the infant brain : a look at gamma band oscillatory activity in response to eye gaze cues| old_uid | 3094 |
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| title | Decoding social signals in the infant brain : a look at gamma band oscillatory activity in response to eye gaze cues |
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| start_date | 2007/06/25 |
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| schedule | 12h |
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| online | no |
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| location_info | salle 341-344 |
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| details | Hôte : Nathalie George |
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| summary | In this talk, I will present a series of experiments in which gamma band oscillatory brain activity was measured to examine the neural basis of young infants’ perception of eye gaze direction. In a first study, infants were presented with photographic images of upright and inverted female faces directing their gaze towards them or to the side. Direct gaze compared to averted gaze in upright faces elicited increased early evoked gamma activity at occipital channels indicating enhanced neural processing during the earliest steps of face encoding. Direct gaze also elicited a later induced gamma burst over right prefrontal channels, suggesting that eye contact detection might recruit very similar cortical regions as in adults. An induced gamma burst in response to averted gaze was observed over right posterior regions, which might reflect neural processes associated with shifting spatial attention. Inverted faces did not produce such effects, confirming that the gamma band oscillations observed in response to gaze direction are specific to upright faces. In a second study, the question was addressed how flexibly infants can use eye gaze cues even if the head is oriented away from them. The results revealed that although the effects of gaze direction on the early evoked occipital gamma and posterior induced gamma were replicated, perception of direct gaze did not result in a prefrontal induced gamma response. Therefore, in a third study, it was examined whether biological motion (i.e. gaze shift) would help infants to detect eye contact in the context of an averted head. Indeed, when dynamic gaze cues were provided an induced prefrontal gamma effect was observed in response to direct gaze. All in all, these data demonstrate the use of gamma band oscillations in examining the development of social gaze perception and suggest an early specialization of cortical regions known to process eye gaze. These findings will be discussed in the light of behavioural work with newborn infants and neuro-imaging findings with adults. |
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| responsibles | Baillet |
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