Abnormal response to performance feedback

Another concept related to cognitive processing of emotional material and to mood-congruent bias is that of reinforcement or reward. It has been argued that the manifold signs and symptoms of manic depression may be viewed in terms of dysregulation of three major neurobiological systems: those that involve reinforcement—reward functions, central pain mechanisms and psychomotor activity (Carroll, 1994). Although research has yet to demonstrate a disturbance of reinforcement—reward systems in bipolar disorder, a series of related studies has suggested that such systems may be disrupted in patients with major depression (Beats et al, 1996; Elliott et al, 1996, 1997a). Sahakian and colleagues have suggested that an abnormal response to negative feedback may contribute to the poor performance often observed in individuals with depression. Specifically, Elliott et al (1996) found that on two CANTAB computerised neuropsychological tasks, which tap different cognitive functions and involve different neural substrates, failure on one problem appeared to elevate the probability of failure on the immediately subsequent problem, suggesting that negative feedback may have a detrimental effect on subsequent performance. This effect was specific to patients with depression and was not observed in any of the other clinical groups examined, i.e. those with Parkinson's disease, schizophrenia or neurosurgical legions of the frontal or temporal lobes (Elliott et al, 1997a). The investigators suggested that this effect may represent an important link between negative affect and the cognitive impairments associated with depression. Whether this type of effect is specific to depression or extends to patients who are manic at the time of testing, however, remains to be determined. In this regard, it is worth mentioning that in a study investigating the neural response to performance feedback, the presence of feedback increased blood flow in the ventromedial/orbitofrontal cortex for a guessing but not for a planning task (Elliott et al, 1997b, 1998).

Also relevant is a study by Corwin et al (1990) that investigated response bias (i.e. the decision rule subjects adopt when uncertain) on a task of recognition memory in patients with unipolar depression, bipolar mania and controls. An abnormally conservative response bias was associated with depression — whereas a liberal response bias was associated with mania, regardless of severity of illness. Consequently it seems that cognitive performance in depression and mania may be influenced by different emotional or affective responses to task stimuli.

Previous SectionNext Section