Experience-dependent coding of facial expression in superior temporal sulcus.
Sensory information from the external world is inherently ambiguous, necessitating prior experience as a constraint on perception. Prolonged experience (adaptation) induces perception of ambiguous morph faces as a category different from the adapted category, suggesting sensitivity in underlying neural codes to differences between input and recent experience. Using magnetoencephalography, we investigated the neural dynamics of such experience-dependent visual coding by focusing on the timing of responses to morphs after facial expression adaptation. We show that evoked fields arising from the superior temporal sulcus (STS) reflect the degree to which a morph and adapted expression deviate. Furthermore, adaptation effects within STS predict the magnitude of behavioral aftereffects. These findings show that the STS codes expressions relative to recent experience rather than absolutely and may bias perception of expressions. One potential neural mechanism for the late timing of both effects appeals to hierarchical models that ascribe a central role to backward connections in mediating predictive codes.
Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, 12 Queen Square, London WC1N 3BG, United Kingdom. n.furl@fil.ion.ucl.ac.uk
Nicholas
N
Furl
Nicola J
NJ
van Rijsbergen
Alessandro
A
Treves
Karl J
KJ
Friston
Raymond J
RJ
Dolan
D005145:Face; D006801:Humans; D015225:Magnetoencephalography; D013702:Temporal Lobe / Q000502:physiology*