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Early Left Parietal Activity Elicited by Direct Gaze: A High-Density EEG Study

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ABSTRACT

Gaze is one of the most important cues for human communication and social interaction. In particular, gaze contact is the most primary form of social contact and it is thought to capture attention. A very early-differentiated brain response to direct versus averted gaze has been hypothesized. Here, we used high-density electroencephalography to test this hypothesis. Topographical analysis allowed us to uncover a very early topographic modulation (40–80 ms) of event-related responses to faces with direct as compared to averted gaze. This modulation was obtained only in the condition where intact broadband faces–as opposed to high-pass or low-pas filtered faces–were presented. Source estimation indicated that this early modulation involved the posterior parietal region, encompassing the left precuneus and inferior parietal lobule. This supports the idea that it reflected an early orienting response to direct versus averted gaze. Accordingly, in a follow-up behavioural experiment, we found faster response times to the direct gaze than to the averted gaze broadband faces. In addition, classical evoked potential analysis showed that the N170 peak amplitude was larger for averted gaze than for direct gaze. Taken together, these results suggest that direct gaze may be detected at a very early processing stage, involving a parallel route to the ventral occipito-temporal route of face perceptual analysis.

No MeSH data available.


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Example stimulus under each experimental condition of picture filtering (broadband / high spatial frequency / low spatial frequency) and gaze direction (direct / averted).These avatar faces were created with FaceGen Modeller 3.5 (see [45] for details).
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pone.0166430.g001: Example stimulus under each experimental condition of picture filtering (broadband / high spatial frequency / low spatial frequency) and gaze direction (direct / averted).These avatar faces were created with FaceGen Modeller 3.5 (see [45] for details).

Mentions: The same stimuli as in Burra et al. (2013) were used (Fig 1). In brief, there were six different avatar face identities (3 male), each with direct and (right + left) averted gaze. Each picture was 512 pixels by 512 pixels (~6 degrees of visual angle). We used a wavelet decomposition to obtain the high (> 32 cycles/image) and low (< 6 cycles/image) spatial frequency versions of the faces [47].


Early Left Parietal Activity Elicited by Direct Gaze: A High-Density EEG Study
Example stimulus under each experimental condition of picture filtering (broadband / high spatial frequency / low spatial frequency) and gaze direction (direct / averted).These avatar faces were created with FaceGen Modeller 3.5 (see [45] for details).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5120811&req=5

pone.0166430.g001: Example stimulus under each experimental condition of picture filtering (broadband / high spatial frequency / low spatial frequency) and gaze direction (direct / averted).These avatar faces were created with FaceGen Modeller 3.5 (see [45] for details).
Mentions: The same stimuli as in Burra et al. (2013) were used (Fig 1). In brief, there were six different avatar face identities (3 male), each with direct and (right + left) averted gaze. Each picture was 512 pixels by 512 pixels (~6 degrees of visual angle). We used a wavelet decomposition to obtain the high (> 32 cycles/image) and low (< 6 cycles/image) spatial frequency versions of the faces [47].

View Article: PubMed Central - PubMed

ABSTRACT

Gaze is one of the most important cues for human communication and social interaction. In particular, gaze contact is the most primary form of social contact and it is thought to capture attention. A very early-differentiated brain response to direct versus averted gaze has been hypothesized. Here, we used high-density electroencephalography to test this hypothesis. Topographical analysis allowed us to uncover a very early topographic modulation (40&ndash;80 ms) of event-related responses to faces with direct as compared to averted gaze. This modulation was obtained only in the condition where intact broadband faces&ndash;as opposed to high-pass or low-pas filtered faces&ndash;were presented. Source estimation indicated that this early modulation involved the posterior parietal region, encompassing the left precuneus and inferior parietal lobule. This supports the idea that it reflected an early orienting response to direct versus averted gaze. Accordingly, in a follow-up behavioural experiment, we found faster response times to the direct gaze than to the averted gaze broadband faces. In addition, classical evoked potential analysis showed that the N170 peak amplitude was larger for averted gaze than for direct gaze. Taken together, these results suggest that direct gaze may be detected at a very early processing stage, involving a parallel route to the ventral occipito-temporal route of face perceptual analysis.

No MeSH data available.


Related in: MedlinePlus