The neural substrate of bias mood-processing in patients with first-episode depression: a functional magnetic resonance imaging study with emotional picture stimuli

Abstract

Objeefive To explore the neural substrate of bias mood-processing in depression by probing the differences of neural activation associated with reactivity to different affective stimuli clues.Methods Forteen patients with depressive disorder and 14 healthy subjects were scanned with functional magnetic resonance imaging(fMRI)on three occasions based on block-design,during whicn positive,neutral and negative affective visual stimuli from International Affective Pictures System(IAPS)were presented Patients were then treated with venlafaxine(75-150 mg/d)for 12 weeks,and the symptoms were evaluated with the Hamilton Depression Scale(HAMD17).The Analyze of functional neural xmage (AFNI)was used to examine the fMRI data.Results The respective response rates were 58%and 92%after 8-and 12-week venlafaxine treatment,with the total reduction rate of HAMD17 score of 60%. The activated cerebral regions in both patients and controls included bilateral middle frontal gyrus,bilateral dorsolateral prefrontal cortex,lefl thalamus,bilateral insular,bilateral temporal,bilateral amygdale and hippocampus.For positive pictures,the activation intensity levels in right middle frontal gynm,left middle frontal gyrus and left thalamus in patients were 0.11%.0.09%and 0.31%respectively.which were significantly lower than that in controls(0.98%,1.17%and 1.32%respectively;P＜0.05).and the activation intensity levels in left insular,risht amygdale and left amygdale were 1.03%,0.47%and 0.11%in patients,which were significantly hisher than that in controls(0.45%. -0.34%and-0.49%respectively;P＜0.05).For negative pictures,the activation intensity levels in left middle frontal gyrus,left dorsolateral prefrontal cortex,left insular,left temporal and risht amygdale were 2.77%,0.18%,1.36%,0.33%and 0.44%,which were hisher than that in controls(1.91%,-0.32%,0.91%,-0.31%,-0.29%respectively;P＜0.05);the activation intensity level in left thalamus was lower than that of the control(-0.79%vs.1.15%;P＜0.05).After venlafaxine treatment,for positive pictures.the increases of the activation intensity levels in bilateral middle frontal gyrus and left thaiamus were 1.21%,1.14%and 1.23%respectively(P＜0.05),and for negative pictures.the decreases of the activation intensity levels in left middle frontal gyrus.left dorsolateral prefrontal cortex and left insular were 2.05%,-0.42%and 0.73%respectively(P＜0.05).Conclusions The abnormal activation in prefrontal lobe,left insular,left temporal,amygdale and left thalamus stimulated by different kinds of mood inducing clues may be associated with bias mood processing in the patients with depression.And the abnormal activation of prefrontal lobe.left insular and thalamus can be regulated after venlafaxine treatment. Key words: Depressive disorder; Magnetic resonance imaging; International affective pictures system; Venlafaxine