Attention inhibition of early cortical activation to fearful faces

Abstract

Several lines of evidence demonstrate that processing facial expression can occur in the first 130 ms following a face presentation, but it remains unclear how this is modulated by attention. We presented neutral, fearful and happy faces to subjects who attended either to repeated identity or to repeated emotions. Brain activity was recorded using magnetoencephalography (MEG) and analyzed with event-related beamforming, providing both temporal and spatial information of processing in the brain. The first MEG component, at 90 ms (M90), was sensitive to facial expression, but only when attention was not directed to expression; non-attended fearful faces increased activation in occipital and right middle frontal gyri. Around 150 ms, activity in several brain regions, regardless of the direction of attention, was larger to emotional compared to neutral faces; attention directed to facial expressions increased activity in the right fusiform gyrus and the anterior insula bilaterally. M220 was not modulated by individual facial expressions; however, attention directed to facial expressions enhanced activity in the right inferior parietal lobe and precuneus, while attention directed to identity enhanced posterior cingulate activity.These data demonstrate that facial expression processing involves frontal brain areas as early as 90 ms. Attention directed to emotional expressions obscured this early automatic processing but increased the M170 activity. The M220 sources varied with the direction of attention. Thus, the pattern of neural activation to faces varied with attention to emotions or to identity, demonstrating separate and only partially overlapping networks for these two facets of information contained in faces.