Cortical Inefficiency in Patients with Unipolar Depression: An Event-Related fMRI Study with the Stroop Task

Prefrontal mechanisms for executive control over emotional distraction are altered in major depression

“…Decreased activation was observed in response to targets overall collapsing the target subtypes in bilateral MFG, indicating the task importance in influencing fMRI results in MDD. Two recent studies in medication-free MDD patients revealed increased prefrontal activation during effortful cognitive tasks compared to the controls (Matsuo et al, 2006, Wagner et al, 2006. Although antidepressant medication use may influence the fMRI findings in MDD (Mayberg et al, 2000, Davidson et al, 2003, Fu et al, 2004, task differences may also greatly contribute to the discrepancy in findings across studies as evident by our current study (discrepancy of activation in the MFG to overall targets and target subtypes).…”

“…Based on the model proposed by Cohen and colleagues , multiple representations of stimuli would increase the activity in dorsolateral PFC. Alternatively, the increased activation to the Target-after-Sad stimuli in MDD might be a compensatory effect for the insufficient conflict control and inhibition in the left ACC and right IFG (Harvey et al, 2005, Wagner et al, 2006. Nevertheless, the increased activation in the MDD group is limited to the targets following sad stimuli.…”

Enhanced rostral anterior cingulate cortex activation during cognitive control is related to orbitofrontal volume reduction in unipolar depression

“…9 In our previous study with the Stroop Color-Word Test (SCWT), 10 an established neuropsychological test taxing cognitive inhibition processes, we directly tested the hypothesis of disrupted prefrontal and anterior cingulate functions. 11 Our main finding was that patients showed a behavioural performance and dorsal ACC (dACC) activity comparable to healthy control subjects but a relative hyperactivity in the rostral ACC (rACC) and left DLPFC. The rACC activity correlated positively with the Stroop interference (more time spent to inhibit the word reading during the incongruent v. the congruent condition) and with left DLPFC activity.…”

“…We described the several analysis steps in detail in our previous paper. 11 The functional data were corrected for differences in time acquisition by sinc interpolation, realigned at the first image of every session, normalized to the Montreal Neurological Institute (MNI) reference brain and smoothed with a Gaussian kernel (10 mm, full width at half maximum [FWHM]). The data were subsequently analyzed voxel-wise within the general linear model to calculate statistical parametric maps of t statistics for condition-specific effects.…”

“…Although the meaning of this physiological baseline is not fully understood, there are suggestions that this activity in the midline cortical areas can be interpreted in terms of continuous self-referential processing. 18 One prominent area within the default mode brain network is the VMPFC including the rACC; in our previous fMRI study, 11 activity relative to baseline was elevated in patients and decreased in healthy control subjects during the Stroop task.…”