Fronto-limbic circuitry in euthymic bipolar disorder: Evidence for prefrontal hyperactivation

Atypical right hemispheric functioning in the euthymic state of bipolar affective disorder

“…In line with previous neuroimaging studies on euthymic BD patients (e.g., Wessa et al, 2007;Robinson et al, 2008;Chen et al, 2010;Keener et al, 2012) our results suggest that right hemisphere dysfunction is not necessarily related to BD symptoms.…”

“…For example, Chen et al (2010) reported increased activation in the right amygdala and right orbitofrontal cortex in euthymic BD patients relative to healthy controls during a facial emotion task in which participants were explicitly asked to rate the affective intensity of faces depicting one of six emotion types (happiness, sadness, disgust, fear, surprise, and anger). Atypical increase in right prefrontal activation in euthymic BD patients was also found with an emotional face matching task (Robinson et al, 2008), and an emotional go/no-go paradigm where subjects responded to a target emotional face (Wessa et al, 2007).…”

“…If this were to be true, the question arises as to how such an adaptive strategy is achieved. One explanation is that hyperactivation of the right hemisphere, as frequently reported in BD (e.g., Wessa et al, 2007;Robinson et al, 2008;Chen et al, 2010), might simply indicate an increased effort of the right hemisphere in emotion processing (Morris et al, 2012).…”

“…Although only a few previous studies differentiated between symptomatic and euthymic BD patients (e.g., Wessa et al, 2007;Robinson et al, 2008;Chen et al, 2010;Keener et al, 2012), the majority of these studies also found atypical functional hemispheric asymmetries in emotion perception involving the right fronto-amygdala network in symptom free BD patients. For example, Chen et al (2010) reported increased activation in the right amygdala and right orbitofrontal cortex in euthymic BD patients relative to healthy controls during a facial emotion task in which participants were explicitly asked to rate the affective intensity of faces depicting one of six emotion types (happiness, sadness, disgust, fear, surprise, and anger).…”

Reward Processing in Unipolar and Bipolar Depression: A Functional MRI Study

“…An alternative interpretation of these results could be greater abnormal regulation processes in BD. Different studies reported changes in prefrontal regulation in affective disorders that differentiates UD and BD, particular connectivity patterns between the orbital frontal cortex and the amygdala (Almeida et al, 2009;Robinson et al, 2008). Similar processes could be in play in the context of reward processing, meaning that the reported result of a most blunted NAcc activity is not necessarily related to reward outcome, but with regulation abnormalities that take part before the outcome processing.…”