Abnormal, affect-specific modulatory effects on early auditory processing in schizophrenia: magnetoencephalographic evidence.

Abnormalities in the perception and identification of emotions have frequently been reported in schizophrenia. Hemodynamic neuroimaging studies found functional abnormalities in cortical and subcortical brain circuits that are involved in normal affective processing, but the temporal dynamics of abnormal emotion processing in schizophrenia remain largely elusive. To investigate this issue, we recorded early auditory evoked field components by means of whole-head magnetoencephalography that were in response to emotion-associated tones in seventeen patients with schizophrenia and in seventeen healthy, matched controls. Forty-two click-like tones (conditioned stimuli; CS) acquired differential emotional meaning through an affective associative learning procedure by pairing each CS three times with either pleasant, unpleasant or neutral auditory scenes. As expected, differential affect-specific modulation in patients vs. controls was evident, starting at the auditory N1m onset latency of approximately 70ms, extending to 230ms. While controls showed the expected enhanced processing of emotion associated CS, patients revealed an inverted pattern with reduced processing of arousal, when compared to neutral stimuli, in the right prefrontal cortex. The present finding suggests impairments in the prioritization of emotionally salient vs. non-salient stimuli in patients with schizophrenia. Dysfunction in higher cognitive processes and behavior in schizophrenia may therefore reflect dysfunction in fundamental, early emotion processing stages.

Implicit and explicit procedural learning in patients recently remitted from severe major depression.

In acute depression a high prevalence of deficits in learning and memory performance has been reported. Still, it is unclear whether these cognitive deficits are present after remission of clinical symptoms of depression. The present study compared 20 inpatients recently remitted from severe major depressive disorder (MDD) with 20 healthy matched control participants on two sequence learning tasks: a modified serial reaction-time task (SRT) for implicit learning, which is sensitive to subcortical and frontal impairments, and a serial generation task (SGT) for explicit learning. As compared with performance in healthy controls, implicit and explicit learning were not impaired in recently remitted inpatients with depression. Intentional acquisition of new information was related to the severity of depressive symptoms as patients with higher scores on Beck's Depression Inventory (BDI) showed poorer explicit learning. In contrast to findings in acute depression, our results suggest a normal degree of learning in remitted depression; these findings are consistent with unimpaired fronto-striatal functioning. However, although not statistically significant, patients remitted from melancholic MDD revealed poorer implicit learning performance compared with patients remitted from non--melancholic MDD. Longitudinal studies in patients with melancholic vs. non-melancholic MDD are needed to investigate the course of cognitive functioning during the recovery from MDD.