[Abstract Title]. - Society for Neuroscience

Poster
260. Objects and Faces in Humans II
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 260.5/BB17
Topic: D.04.j. Processing of objects and faces
Title: Enhanced activation in face regions during false categorisation of Mooney images as
faces
Authors: *E. GENC 1,2 , C. TILLMANN 1,2,3 , W. SINGER 1,2,4 , P. UHLHAAS 1,2,3 , A.
KOHLER 1,2 ;
1 Dept. of Neurophysiol., Max Planck Inst., Frankfurt am Main, Germany; 2 Brain Imaging Ctr.,
Frankfurt am Main, Germany; 3 Lab. for Neurophysiol. und Neuroimaging, 4 Frankfurt Inst. for
Advanced Studies, J.W. Goethe Univ., Frankfurt am Main, Germany
Abstract: There is a large body of evidence that several areas in the ventral temporal cortex are
involved in face processing. Research has focused on a region in the fusiform gyrus that
responds stronger to faces compared to other objects. To date, there are few studies addressing
the whole network that subserves face perception. Here, we used fMRI and ambiguous face
stimuli to study the neural correlates of categorizing stimuli as faces.
Functional MR images with standard BOLD contrast were obtained from 22 healthy subjects.
Using a rapid event-related design, subjects were presented with a random sequence of upright
and inverted-scrambled Mooney stimuli. Mooney stimuli are degraded pictures of human faces
in which contrast is maximized to black-and-white. Stimulus duration was 200 ms and subjects
indicated whether they detected a face or not via button press after each stimulus. Subjects
performed four functional runs within one scanning session. High-resolution anatomical images
for coregistration and display of functional data were obtained from each subject in the same
session.
Four stimulus-response constellations were considered for analysis: i.e. upright stimuli
recognized as faces („hits‟, 83% of the trials), upright stimuli classified as non-faces („misses‟,
14%), inverted stimuli recognized as non-faces („correct rejections‟, 82%), and inverted stimuli
classified as faces („false alarms‟, 14%). BOLD signal time courses for the different
constellations were estimated with a deconvolution analysis, based on a general linear model.
Following previous studies using Mooney stimuli (Andrews & Schluppeck, 2004), the difference
in BOLD activity was computed for events when a face was perceived (hits and false alarms)
compared to when no face was perceived (misses and correct rejections). This contrast revealed
an increase in BOLD activity in the fusiform face area (FFA) (bilateral), the superior temporal
sulcus (STS) (right hemisphere), and the occipital face area (OFA) (right hemisphere). Amygdala
and orbito-frontal areas also showed significant increases in activity when a face was perceived.