ORCID Profile
0000-0002-7693-768X
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Publisher: Elsevier BV
Date: 05-2014
DOI: 10.1016/J.NEUROPSYCHOLOGIA.2014.04.003
Abstract: In social interactions, the location of relevant stimuli is often indicated by the orientation of gaze. It has been proposed that the direction of gaze might produce an automatic cueing of attention, similar to what is observed with exogenous cues. However, several reports have challenged this claim by demonstrating that the behavioral gain that arises with gaze cueing could be explained by shifts of attention, which are intentional and not automatic. We reasoned that if cueing by gaze was truly automatic, it should occur without awareness and should be sustained by subcortical circuits, including the amygdalae, independently of the main geniculo-striate visual pathway. We presented a cross-modal version of the Posner cueing paradigm to a patient (TN) with bilateral lesions of occipital cortex (Burra et al., 2013 Pegna, Khateb, Lazeyras, & Seghier, 2005). TN was asked to localize a sound using a key press. The location of the sound was congruent or incongruent with the direction of gaze of a face-cue. In groups of healthy young and age-matched participants, we observed significantly longer response times for incongruent than congruent sounds, suggesting that gaze direction interfered with processing of localized sounds. By contrast, TN׳s performance was not affected by sound-gaze congruence. The results suggest that the processing of gaze orientation cannot occur in the absence of geniculo-striate processing, suggesting that it is not automatic.
Publisher: California Digital Library (CDL)
Date: 29-10-2017
Abstract: Gender categorisation of human faces is facilitated when gaze is directed toward the observer (i.e., a direct gaze), compared to situations where gaze is averted or the eyes are closed (Macrae, Hood, Milne, Rowe, & Mason, 2002). However, the temporal dynamics underlying this phenomenon remain to some extent unknown. Here, we used electroencephalography (EEG) to assess the neural correlates of this effect, focusing on the event-related potential (ERP) components known to be sensitive to gaze perception, i.e., P1, N170, and P3b. We first replicated the seminal findings of Macrae et al. (Experiment 1) regarding facilitated gender discrimination, and subsequently measured the underlying neural responses. Our data revealed an early preferential processing of direct gaze as compared to averted gaze and closed eyes at the P1, which reverberated at the P3b (Experiment 2). Critically, using the same material, we failed to reproduce these effects when gender categorisation was not required (Experiment 3). Taken together, our data confirm that direct gaze enhances both early and late cortical responses to face processing, although this effect appears to be task-dependent.
Publisher: Society for Neuroscience
Date: 19-06-2013
Publisher: Elsevier BV
Date: 05-2017
DOI: 10.1016/J.NEUROPSYCHOLOGIA.2017.10.009
Abstract: The human brain can process facial expressions of emotions rapidly and without awareness. Several studies in patients with damage to their primary visual cortices have shown that they may be able to guess the emotional expression on a face despite their cortical blindness. This non-conscious processing, called affective blindsight, may arise through an intact subcortical visual route that leads from the superior colliculus to the pulvinar, and thence to the amygdala. This pathway is thought to process the crude visual information conveyed by the low spatial frequencies of the stimuli. In order to investigate whether this is the case, we studied a patient (TN) with bilateral cortical blindness and affective blindsight. An fMRI paradigm was performed in which fearful and neutral expressions were presented using faces that were either unfiltered, or filtered to remove high or low spatial frequencies. Unfiltered fearful faces produced right amygdala activation although the patient was unaware of the presence of the stimuli. More importantly, the low spatial frequency components of fearful faces continued to produce right amygdala activity while the high spatial frequency components did not. Our findings thus confirm that the visual information present in the low spatial frequencies is sufficient to produce affective blindsight, further suggesting that its existence could rely on the subcortical colliculo-pulvino-amygdalar pathway.
Publisher: Springer Science and Business Media LLC
Date: 07-05-2018
DOI: 10.3758/S13415-018-0605-5
Abstract: Gender categorisation of human faces is facilitated when gaze is directed toward the observer (i.e., a direct gaze), compared with situations where gaze is averted or the eyes are closed (Macrae, Hood, Milne, Rowe, & Mason, Psychological Science, 13(5), 460-464, 2002). However, the temporal dynamics underlying this phenomenon remain to some extent unknown. Here, we used electroencephalography (EEG) to assess the neural correlates of this effect, focusing on the event-related potential (ERP) components known to be sensitive to gaze perception (i.e., P1, N170, and P3b). We first replicated the seminal findings of Macrae et al. (2002, Experiment 1) regarding facilitated gender discrimination, and subsequently measured the underlying neural responses. Our data revealed an early preferential processing of direct gaze as compared with averted gaze and closed eyes at the P1, which reverberated at the P3b (Experiment 2). Critically, using the same material, we failed to reproduce these effects when gender categorisation was not required (Experiment 3). Taken together, our data confirm that direct gaze enhances the early P1, as well as later cortical responses to face processing, although the effect appears to be task dependent.
Publisher: Elsevier BV
Date: 02-2018
DOI: 10.1016/J.NEULET.2017.11.031
Abstract: The distribution of retino-tectal projections is dissimilar depending on whether the receptors are situated in the nasal and temporal visual hemiretinas. Indeed, it has been claimed that the superior colliculus receives a greater proportion of its input from the temporal visual hemifield (nasal hemi-retina) relative to the nasal hemifield (temporal hemi-retina). In order to investigate whether these subcortical projections influence face processing, we investigated the early cortical ERP responses to faces and houses presented in the temporal and nasal retinas using monocular viewing. Neutral or fearful faces were presented concurrently with houses on either side of a central fixation cross, while participants were asked to discriminate changes in luminance at the center. Results showed that the lateralized N170, computed as the contralateral-ipsilateral electrode difference, was greater for faces appearing in the nasal relative to the temporal visual hemifield. This was due to a greater ipsilateral N170 for temporal relative to nasal presentations. By contrast, no difference was found across emotional expressions. The enhanced ERP response to faces appearing in the temporal visual field, suggests that the retinotectal pathway modulates cortical processing, most likely through activation of a colliculo-pulvino-amygdalar pathway, with subsequent back-projections from the amygdala to visual cortical regions. However, unattended facial expressions do not seem to modulate the response, at least at these angles of eccentricity.
No related grants have been discovered for Nicolas Burra.