Impact of emotional valence on mismatch negativity in the course of cortical face processing.

Various aspects of cortical face processing have been studied by assessing event related potentials (ERP). It has been described in the literature that mismatch negativity (MMN), a well-studied ERP, is not only modulated by sensory features but also emotional valence. However, the exact impact of emotion on the temporo-spatial profile of visual MMN during face processing remains inconsistent. By employing a sequential oddball paradigm using both neutral and emotional deviants, we were able to differentiate two distinct vMMN subcomponents. While an early subcomponent at 150-250 ms is elicited by emotional salient facial stimuli, the later subcomponent at 250-400 ms seems to reflect the detection of regularity violations in facial recognition per se, unaffected by emotional salience. Our results suggest that emotional valence is encoded in vMMN signal strength at an early stage of facial processing. Furthermore, we assume that of facial processing consists of temporo-spatially distinct, partially overlapping levels concerning different facial aspects.

Motor cognition in schizophrenia: Control of automatic imitation and mapping of action context are reduced.

The ability to imitate is considered impaired in schizophrenia patients. This assumption, however, is based on heterogeneous studies mostly targeting voluntary imitation, e.g., pantomime. Studies on automatic imitation, however, and on underlying mechanisms of top-down inhibition of automatic imitation and contextual modulation in schizophrenia are highly limited. We employed two sensorimotor paradigms to examine imitation-inhibition and action context mapping in 37 schizophrenia patients and 36 matched controls. In the first experiment, participants performed finger lifts while observing a hand executing compatible or incompatible finger lifts from the third-person perspective. The compatibility or incompatibility of these finger lifts affected participants' reaction times (RTs). The comparison of between-condition RT differences shows a larger movement compatibility effect in schizophrenia than in controls. The second experiment involved finger lifts while watching a still hand, from the first-person perspective, with constrained fingers that either corresponded or did not correspond to the participants' response fingers. Here, schizophrenia patients showed a diminished RT slowing in corresponding constraint trials. While the former results provide evidence for an impaired control of imitation in patients with schizophrenia, the latter results indicate a reduced encoding of action context. In conclusion, this study provides the first evidence for deficits of top-down control of imitation and motor context processing in the same sample of schizophrenia patients.

Mapping adaptation, deviance detection, and prediction error in auditory processing.

Various studies have suggested that auditory deviance detection is organized in a hierarchical manner with ascending levels of complexity. Event-related potentials (ERP) are considered to reflect different cortical processing stages. In the current electroencephalographic study, we employed an auditory sequence oddball paradigm to investigate different levels of cortical auditory processing and the contribution of neuronal habituation and prediction error mechanism to N1 and Mismatch Negativity (MMN). Our findings suggest that N1 reflects a lower cortical process primarily involved in the encoding of simple physical features and is thus mainly modulated by neuronal attenuation and not complex top-down mechanisms. By analyzing within-sequence signal differences, we divided the MMN into distinct subcomponents reflecting different hierachical levels of auditory processing. We determined a "first-order" MMN that reflects the processing of simple deviant features (such as frequency) and "higher-order" MMNs that occur at regularity violation of complex patterns or unexpected inputs that do not allow further predictions. In our source localization analysis, both the primary auditory cortex and left IFG were primarily involved in the detection of simple, physically deviant features, while the right IFG was associated with the processing of novel, unexpected auditory inputs and the ACC with regularity violation of known patterns. Summarizing, our results might contribute to a better understanding of the different complexities of neuronal habituation and prediction error mechanisms at different levels of cortical auditory processing.