Ema Thomas - Academia.edu (original) (raw)

Papers by Ema Thomas

Frontiers in Human Neuroscience, 2009

regions. However, changes in cortical regions are less consistently observed and depend on the ex... more regions. However, changes in cortical regions are less consistently observed and depend on the experimental paradigm used. This view is supported by another meta-analysis (Fitzgerald et al., 2006), focusing specifi cally on studies reporting dorsolateral prefrontal cortex (DLPFC) abnormalities. They concluded that while abnormalities were reported relatively consistently, the direction and laterality of observed changes varied depending on the challenge used. Broadly speaking, cognitive challenges used in functional neuroimaging of depression can be divided into non-emotional challenges and emotional challenges, requiring either overt or covert affective processing. NON-EMOTIONAL COGNITIVE NEUROIMAGING IN CURRENT DEPRESSION Executive function and working memory Relatively few studies have examined the neural substrates of nonemotional cognitive defi cits in unipolar depression. These have typically focused on executive tasks that depend on functional integrity of the prefrontal cortices. Elliott et al. (1997a) used positron emission tomography to compare neural activity in controls and depressed participants performing a complex planning task. They found that while the groups showed similar overall patterns of activity, this was globally attenuated in depressed subjects, particularly in caudate, thalamus, anterior cingulate (ACC), DLPFC and ventrolateral prefrontal cortex (VLPFC). Task performance in the depressed group was also impaired, suggesting that these attenuations may have refl ected poorer performance. By contrast, Fitzgerald et al. (2008) used a similar planning task with fMRI and reported that depressed participants showed increased activity in regions including right VLPFC, DLPFC and angular gyrus/cuneus. Unlike patients in the Elliott et al. (1997a) study, their performance accuracy was normal. This discrepancy may explain the activation differences, with Fitzgerald et al.'s COGNITIVE ACTIVATION STUDIES IN DEPRESSION Haldane and Frangou (2006) reviewed functional neuroimaging studies in mood disorders and concluded that most report associations between depression and increased activity in limbic

Frontiers in Human Neuroscience, 2009

regions. However, changes in cortical regions are less consistently observed and depend on the ex... more regions. However, changes in cortical regions are less consistently observed and depend on the experimental paradigm used. This view is supported by another meta-analysis (Fitzgerald et al., 2006), focusing specifi cally on studies reporting dorsolateral prefrontal cortex (DLPFC) abnormalities. They concluded that while abnormalities were reported relatively consistently, the direction and laterality of observed changes varied depending on the challenge used. Broadly speaking, cognitive challenges used in functional neuroimaging of depression can be divided into non-emotional challenges and emotional challenges, requiring either overt or covert affective processing. NON-EMOTIONAL COGNITIVE NEUROIMAGING IN CURRENT DEPRESSION Executive function and working memory Relatively few studies have examined the neural substrates of nonemotional cognitive defi cits in unipolar depression. These have typically focused on executive tasks that depend on functional integrity of the prefrontal cortices. Elliott et al. (1997a) used positron emission tomography to compare neural activity in controls and depressed participants performing a complex planning task. They found that while the groups showed similar overall patterns of activity, this was globally attenuated in depressed subjects, particularly in caudate, thalamus, anterior cingulate (ACC), DLPFC and ventrolateral prefrontal cortex (VLPFC). Task performance in the depressed group was also impaired, suggesting that these attenuations may have refl ected poorer performance. By contrast, Fitzgerald et al. (2008) used a similar planning task with fMRI and reported that depressed participants showed increased activity in regions including right VLPFC, DLPFC and angular gyrus/cuneus. Unlike patients in the Elliott et al. (1997a) study, their performance accuracy was normal. This discrepancy may explain the activation differences, with Fitzgerald et al.'s COGNITIVE ACTIVATION STUDIES IN DEPRESSION Haldane and Frangou (2006) reviewed functional neuroimaging studies in mood disorders and concluded that most report associations between depression and increased activity in limbic