RT Journal Article
SR Electronic
T1 The Faces of Predictive Coding
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 8997
OP 9006
DO 10.1523/JNEUROSCI.1529-14.2015
VO 35
IS 24
A1 Alla Brodski
A1 Georg-Friedrich Paasch
A1 Saskia Helbling
A1 Michael Wibral
YR 2015
UL http://www.jneurosci.org/content/35/24/8997.abstract
AB Recent neurophysiological accounts of predictive coding hypothesized that a mismatch of prediction and sensory evidence—a prediction error (PE)—should be signaled by increased gamma-band activity (GBA) in the cortical area where prediction and evidence are compared. This hypothesis contrasts with alternative accounts where violated predictions should lead to reduced neural responses. We tested these hypotheses by violating predictions about face orientation and illumination direction in a Mooney face-detection task, while recording magnetoencephalographic responses in a large sample of 48 human subjects. The investigated predictions, acquired via lifelong experience, are known to be processed at different time points and brain regions during face recognition.Behavioral responses confirmed the induction of PEs by our task. Beamformer source analysis revealed an early PE signal for unexpected orientation in visual brain areas followed by a PE signal for unexpected illumination in areas involved in 3D shape from shading and spatial working memory. Both PE signals were reflected by increases in high-frequency (68–140 Hz) GBA. In high-frequency GBA we also observed a late interaction effect in visual brain areas, probably corresponding to a high-level PE signal. In addition, increased high-frequency GBA for expected illumination was observed in brain areas involved in attention to internal representations. Our results strongly support the hypothesis that increased GBA signals PEs. Additionally, GBA may represent attentional effects.