Amygdala
activation at 3T in response to human and avatar facial expressions
of emotions.
Moser
E.ab, Derntl B.ac, Robinson S.a,
Fink B.d, Gur R.C.b, Grammer K.e
a MR Centre
of Excellence, Medical University of Vienna, Vienna, Austria
b Department for Psychiatry, University of Pennsylvania Medical Centre,
Philadelphia, PA, USA
c Faculty of Psychology, University of Vienna, Vienna, Austria
d Department for Sociobiology/Anthropology, University of Goettingen,
Goettingen, Germany
e Ludwig-Boltzmann-Institute for Urban Ethology, Vienna, Austria
Journal
of Neuroscience Methods. 2006 Nov 24; [Epub ahead of print]PMID:
17126910
Facial expressions
of emotions are important in nonverbal communication. Although numerous
neural structures have been identified to be involved
in emotional face processing, the amygdala is thought to be a core
moderator. While previous studies have relied on facial images
of humans, the present study is concerned with the effect of computer-generated
(avatar) emotional faces on amygdala activation. Moreover, elicited activation
patterns in response to viewing avatar faces are compared with the neuronal
responses to human facial expressions of emotions.
Twelvehealthy subjects (five females) performed facial emotion recognition
tasks with optimized 3T event-related fMRI. Robust amygdala activation
was apparent in response to both human and avatar emotional faces, but
the response was significantly stronger to human faces in face-sensitive
structures, i.e. fusiform gyri. We suggest that avatars could be a useful
tool in neuroimaging studies of facial expression processing because
they elicit amygdala activation similarly to human faces, yet have the
advantage of being highly manipulable and fully controllable. However,
the finding of differences between human and avatar faces in face-sensitive
regions indicates the presence of mechanisms by which human brains can
differentiate between them. This mechanism merits further investigation.
In our view
this a breakthrough in stimulus generation for emotions in fmri research.
.
On
the left the reactions to the avatar are shown, on the right those
to the real faces. Note that although both stimuli types
activate almost the same brainregions, the reactions to the avatars (virtual
3d faces) are more differentiated but natural faces evoke higher responses
in face sensitive regions. |
