  Background: Real-time functional magnetic resonance imaging neurofeedback
(rtfMRI-nf) has proven to be a powerful technique to help subjects to gauge and
enhance emotional control. Traditionally, rtfMRI-nf has focused on emotional
regulation through self-regulation of amygdala. Recently, rtfMRI studies have
observed that regulation of a target brain region is accompanied by
connectivity changes beyond the target region. Therefore, the aim of present
study is to investigate the use of connectivity between amygdala and prefrontal
regions as the target of neurofeedback training in healthy individuals and
subjects with a life-time history of major depressive disorder (MDD) performing
an emotion regulation task. Method: Ten remitted MDD subjects and twelve
healthy controls (HC) performed an emotion regulation task in 4 runs of
rtfMRI-nf training followed by one transfer run without neurofeedback conducted
in a single session. The functional connectivity between amygdala and
prefrontal cortex was presented as a feedback bar concurrent with the emotion
regulation task. Participants' emotional state was measured by the Positive and
Negative Affect Schedule (PANAS) prior to and following the rtfMRI-nf.
Psychological assessments were used to determine subjects' history of
depression. Results: Participants with a history of MDD showed a trend of
decreasing functional connectivity across the four rtfMRI-nf runs, and there
was a marginally significant interaction between the MDD history and number of
training runs. The HC group showed a significant increase of frontal cortex
activation between the second and third neurofeedback runs. Comparing PANAS
scores before and after connectivity-based rtfMRI-nf, we observed a significant
decrease in negative PANAS score in the whole group overall, and a significant
decrease in positive PANAS score in the MDD group alone.
