Poster #: 71
Topic: Memory and perception
Thursday, Sep 10, 2015
Emotional face discrimination as revealed by electrophysiological periodic visual responses: an alternative to the vMMN approach
1Psychology, UCLouvain, Louvain la Neuve, Belgium
2p, UCLouvain, Louvain la Neuve, Belgium
Being able to read social information is vital for an individual. A wealth of social cues is provided by the face, particularly emotional expressions. To address the question of how the brain discriminates emotional faces, we recorded electroencephalogram from 18 participants during a fast periodic oddball paradigm (Liu-Shuang et al., 2014, Neuropsychologia, 52, 57-72), which provides an objective, implicit and robust quantifiable measure of visual discrimination. The same face with a neutral expression was presented at a rate of 5.88 Hz during an 80 sec sequence. Every five faces, the same face but displaying an emotional expression of fear, disgust or happiness (in different sequences), was presented, resulting in a sequence NNNNFNNNNFNNNNF (e.g., neutral-fear oddball sequence). The oddball 1.18Hz (5.88Hz/5) response and its harmonics (e.g., 2f = 2.36 Hz) were used to measure emotional face discrimination. This emotional face discrimination response was observed bilaterally at occipito-temporal sites. Furthermore, inverting the faces significantly reduced the brain response over the occipito-temporal regions for the oddball frequency, suggesting that it reflected high level processes related to the emotional faces. A time domain analysis revealed several subsequent components discriminating neutral from emotional faces rather than a single MMN: a positivity, peaking at 120 ms; a negativity, peaking at 170 ms and another positivity, peaking at 250 ms after stimulus onset. These observations highlight the power of the fast periodic oddball paradigm to understand high-level visual discrimination responses such as facial expression or other social cues of faces.