Differentiating patterns of amygdala-frontal functional connectivity in schizophrenia and bipolar disorder

Abstract

Background: Insight into the neural mechanisms underlying the shared and disparate features of schizophrenia (SZ) and bipolar disorder (BD) is limited. The amygdala and prefrontal cortex (PFC) appear to have crucial roles in SZ and BD, yet abnormalities appear to manifest differently in the 2 disorders.

Methods: Eighteen participants with SZ, 18 participants with BD, and 18 healthy controls (HC) underwent resting-state functional magnetic resonance imaging. Resting-state functional connectivity (rsFC) between the PFC and the amygdala divided into 3 subregions (the laterobasal, centromedial, and superficial amygdala) was examined using probabilistic anatomic maps. For each participant, rsFC maps of the 3 amygdala subregions were computed and compared across the 3 groups.

Results: Compared with the HC group, we found significant differences in rsFC between the amygdala and PFC in the SZ and BD groups. In direct comparison between the SZ and BD groups, distinct patterns of rsFC between the amygdala and PFC were observed, particularly in the superficial amygdala. RsFC between the amygdala and the dorsal lateral PFC was significantly decreased in the SZ group, whereas rsFC between the amygdyala and the ventral PFC was significantly decreased in the BD group.

Conclusions: These results strongly suggest dorsal vs ventral PFC differentiation in amygdala-PFC neural system abnormalities between SZ and BD. These regional differences in SZ and BD may give rise to the differences in clinical characteristics observed in SZ and BD, and may implicate potential avenues for differentiating the 2 disorders during early stages of illness.

Keywords: amygdala; bipolar disorder; functional connectivity; prefrontal cortex; resting state; schizophrenia.

Fig. 1.

Functional connectivity between the laterobasal amygdala and dorsal lateral prefrontal cortex in direct comparison between SZ and BD groups. (a) Functional connectivity between the laterobasal amygdala and pregenual anterior cingulate cortex and rostral prefrontal cortex in direct comparison between SZ and BD groups. (b) Error bars represent standard deviation of Z-values at the peak voxel.

Fig. 2.

Functional connectivity between the centromedial amygdala and dorsal lateral prefrontal cortex in the direct comparison between the SZ and BD groups. Error bars represent standard deviation of Z-values at the peak voxel.

Fig. 3.

Functional connectivity between the superficial amygdala and dorsal lateral prefrontal cortex in direct comparison between SZ and BD groups. (a) Top panel: right dorsal lateral prefrontal cortex; bottom panel: left dorsal lateral prefrontal cortex. Functional connectivity between the superficial amygdala and pregenual/ventral anterior cingulate cortex (ACC) and rostral prefrontal cortex and orbitofrontal cortex in direct comparison between the SZ and BD groups. (b) Top panel: right orbitofrontal cortex; middle panel: pregenual/ventral ACC and rostral prefrontal cortex; bottom panel: left orbitofrontal cortex. Error bars represent standard deviation of Z-values at the peak voxel.