Abstract
Classification of neural signals at the single-trial level and the study of their relevance in affective and cognitive neuroscience are still in their infancy. Here we investigated the neurophysiological correlates of conditions of increasing social scene complexity using 3D human models as targets of attention, which may also be important in autism research. Challenging single-trial statistical classification of EEG neural signals was attempted for detection of oddball stimuli with increasing social scene complexity. Stimuli had an oddball structure and were as follows: 1) flashed schematic eyes, 2) simple 3D faces flashed between averted and non-averted gaze (only eye position changing), 3) simple 3D faces flashed between averted and non-averted gaze (head and eye position changing), 4) animated avatar alternated its gaze direction to the left and to the right (head and eye position), 5) environment with 4 animated avatars all of which change gaze and one of which is the target of attention. We found a late (> 300 ms) neurophysiological oddball correlate for all conditions irrespective of their complexity as assessed by repeated measures ANOVA. We attempted single-trial detection of this signal with automatic classifiers and obtained a significant balanced accuracy classification of around 79%, which is noteworthy given the amount of scene complexity. Lateralization analysis showed a specific right lateralization only for more complex realistic social scenes. In sum, complex ecological animations with social content elicit neurophysiological events which can be characterized even at the single-trial level. These signals are right lateralized. These finding paves the way for neuroscientific studies in affective neuroscience based on complex social scenes, and given the detectability at the single trial level this suggests the feasibility of brain computer interfaces that can be applied to social cognition disorders such as autism.
Highlights
Investigating the sensitivity of neurophysiological responses to complex social scenes is becoming an increasingly recognized topic in affective neuroscience [1,2]
Latency analysis showed that latencies were significantly higher at frontal and central sites comparing to parietal sites in the less salient condition (‘Flashed Face—Eye position change’ paradigm)
The goal of the present study was to study and identify the neurophysiological correlates of attention to realistic social scenes which degree of complexity was defined in a defined ordinal manner (Table 1), taking into account the number of items in the scene, elements that define the trajectory of social object and presence of movement
Summary
Investigating the sensitivity of neurophysiological responses to complex social scenes is becoming an increasingly recognized topic in affective neuroscience [1,2]. It is of PLOS ONE | DOI:10.1371/journal.pone.0121970. Neural Signals of Increasing Social Scene Complexity disorders, Overall budget ∼6 million euros, UC budget 850.000 Euros; Hometec QREN –Assisted Living Autism 811417,85; Bial 133/2012 A direct test of the binding by synchrony hypothesis in humans: the neural correlates of coherent object perception, Bial Foundation, 2013, 44.000 Euros; and Bial 133/2012 The role of the core and extended face networks in visual perception and high level social cognition, Bial Foundation, 2013, 46.000 Euros; and grant FCT-UID/ NEU/04539/2013, which covers the publication costs. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
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