Lower effective connectivity between amygdala and parietal regions in response to fearful faces in schizophrenia

Behavioral abnormalities related to processing negative emotions such as fear have been demonstrated in schizophrenia. The amygdala is strongly associated with fear processing, and alterations in amygdala function and structure have been demonstrated in schizophrenia. Further, functional disconnectivity has been attributed as key to the etiology of schizophrenia, with a number of lines of evidence supporting this theory. In the present study, we examine the effective connectivity corresponding to fear processing, from the amygdala to the whole brain, and compare this between patients with schizophrenia and control participants. An implicit facial emotion processing task was performed by 19 patients with schizophrenia and 24 matched controls during fMRI scanning. During the task, participants made gender judgments from facial images with either neutral or fearful emotion. Neural response to fearful images versus neutral was used as contrast of interest to estimate effective connectivity between the amygdala and the whole brain using the psycho-physiological interactions approach. This connectivity was compared between patients with schizophrenia and healthy controls. We show that when looking at fearful compared to neutral faces patients with schizophrenia show significantly reduced effective connectivity from the amygdala to a large cluster of regions including parts of the precuneus and parietal lobe, compared to healthy controls. These regions have been associated with emotion processing and high level social cognition tasks involving self related processing and mental representations about other people. The reduced amygdala connectivity in schizophrenia shown here further illuminates the neural basis for the behavioral abnormalities in emotional and social function found in the disorder.