Abstract
Functional connectivities of the amygdala support emotional and cognitive processing. Life-span development of resting-state functional connectivities (rsFC) of the amygdala may underlie age-related differences in emotion regulatory mechanisms. To date, age-related changes in amygdala rsFC have been reported through adolescence but not as thoroughly for adulthood. This study investigated age-related differences in amygdala rsFC in 132 young and middle-aged adults (19–55 years). Data processing followed published routines. Overall, amygdala showed positive rsFC with the temporal, sensorimotor and ventromedial prefrontal cortex (vmPFC), insula and lentiform nucleus, and negative rsFC with visual, frontoparietal, and posterior cingulate cortex and caudate head. Amygdala rsFC with the cerebellum was positively correlated with age, and rsFCs with the dorsal medial prefrontal cortex (dmPFC) and somatomotor cortex were negatively correlated with age, at voxel p < 0.001 in combination with cluster p < 0.05 FWE. These age-dependent changes in connectivity appeared to manifest to a greater extent in men than in women, although the sex difference was only evident for the cerebellum in a slope test of age regressions (p = 0.0053). Previous studies showed amygdala interaction with the anterior cingulate cortex (ACC) and vmPFC during emotion regulation. In region of interest analysis, amygdala rsFC with the ACC and vmPFC did not show age-related changes. These findings suggest that intrinsic connectivity of the amygdala evolved from young to middle adulthood in selective brain regions, and may inform future studies of age-related emotion regulation and maladaptive development of the amygdala circuits as an etiological marker of emotional disorders.
Highlights
A phylogenetically old nucleus nestled deep in the temporal lobe, the amygdala plays an important role in processing negative emotions
Amygdala resting-state functional connectivities (rsFC) with the bilateral cerebellum and left temporal gyrus increased with age and amygdala rsFC with the right somatomotor cortex and left superior/inferior frontal gyrus decreased with age in men and women combined
In contrast to previous reports of increased amygdala rsFC with the ventromedial prefrontal cortex (vmPFC) from childhood to young adulthood (Gabard-Durnam et al, 2014; Alarcón et al, 2015), the current findings showed that amygdala rsFC with the anterior cingulate cortex (ACC) and vmPFC did not vary with age from young and middle adulthood
Summary
A phylogenetically old nucleus nestled deep in the temporal lobe, the amygdala plays an important role in processing negative emotions. Other studies showed that the amygdala is involved in reward-related learning in a variety of behavioral tasks (Baxter and Murray, 2002). In resting state fMRI the amygdala showed positive connectivity with the ventromedial prefrontal cortex (vmPFC), temporal cortex and subcortical regions, and negative connectivity with the parietal and occipital cortex (Roy et al, 2009; Veer et al, 2012). Increased vmPFC along with decreased amygdala activation may reflect regulation of emotional responses to negative stimuli (Urry et al, 2006). Our earlier work demonstrated that vmPFC activity negatively correlated with and Granger caused skin conductance level, an index of physiological arousal, in support of vmPFC regulation of amygdala response to saliency (Zhang et al, 2012, 2013)
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