Amygdala and fusiform gyrus temporal dynamics: Responses to negative facial expressions
1 Psychiatric Neuroimaging Research Program and Martinos Biomedical Imaging Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
2 Department of Psychology, Tufts University, Medford, MA, USA
3 Department of Psychology, Boston College, Chestnut Hill, MA, USA
4 Current: McLean Hospital, Belmont, MA, USA
5 Division of Cognitive and Behavioral Neurology, Department of Neurology, Brigham and Women's Hospital, Boston, MA, USA
BMC Neuroscience 2008, 9:44 doi:10.1186/1471-2202-9-44Published: 12 May 2008
The amygdala habituates in response to repeated human facial expressions; however, it is unclear whether this brain region habituates to schematic faces (i.e., simple line drawings or caricatures of faces). Using an fMRI block design, 16 healthy participants passively viewed repeated presentations of schematic and human neutral and negative facial expressions. Percent signal changes within anatomic regions-of-interest (amygdala and fusiform gyrus) were calculated to examine the temporal dynamics of neural response and any response differences based on face type.
The amygdala and fusiform gyrus had a within-run "U" response pattern of activity to facial expression blocks. The initial block within each run elicited the greatest activation (relative to baseline) and the final block elicited greater activation than the preceding block. No significant differences between schematic and human faces were detected in the amygdala or fusiform gyrus.
The "U" pattern of response in the amygdala and fusiform gyrus to facial expressions suggests an initial orienting, habituation, and activation recovery in these regions. Furthermore, this study is the first to directly compare brain responses to schematic and human facial expressions, and the similarity in brain responses suggest that schematic faces may be useful in studying amygdala activation.