Reduced P300 and P600 amplitude in the hollow-mask illusion in patients with schizophrenia.

Illusions provide a useful tool to study the mechanisms by which top-down and bottom-up processes interact in perception. Patients suffering from schizophrenia are not as subject to the hollow-mask illusion as healthy controls, since studies have shown that controls perceive a hollow mask as a normal face, while patients with schizophrenia do not. This insusceptibility to the illusion is indicating a weakened top-down processing in schizophrenia and little is understood about the neurobiology of this phenomenon. We used event-related potentials to investigate the hollow-mask illusion in patients with schizophrenia and healthy controls. We hypothesized that there would be a visible reduction of top-down processing in the patients' group and that this reduction would occur in the late stages of processing. We found significantly decreased amplitudes in the P300 and P600 components in the patients' group, indicating that visual information does not benefit from frontal, parietal or temporal activity for perceiving incoming stimuli. We propose that a deficit in functional connectivity may be responsible for impaired top-down visual processing in schizophrenia. These data further the understanding of the time course of top-down processing in patients with schizophrenia.

No departure to "Pandora"? Using critical phenomenology to differentiate "naive" from "reflective" experience in psychiatry and psychosomatic medicine (a comment on Schwartz and Wiggins, 2010).

The mind-body problem lies at the heart of the clinical practice of both psychiatry and psychosomatic medicine. In their recent publication, Schwartz and Wiggins address the question of how to understand life as central to the mind-body problem. Drawing on their own use of the phenomenological method, we propose that the mind-body problem is not resolved by a general, evocative appeal to an all encompassing life-concept, but rather falters precisely at the insurmountable difference between "natural" and a "reflective" experience built into phenomenological method itself. Drawing on the works of phenomenologically oriented thinkers, we describe life as inherently "teleological" without collapsing life with our subjective perspective, or stepping over our epistemological limits. From the phenomenology it can be demonstrated that the hypothetical teleological qualities are a reflective reconstruction modelled on human behavioural structure.

Spontaneous recovery from progressive multifocal leukoencephalopathy in a patient with non-active sarcoidosis.

We report the case of a 50-year-old female patient with non-active sarcoidosis and no kind of immunosuppression, admitted to our hospital because of increasing confusion and focal neurological deficits. Initially a tumor, herpes encephalitis, or neurosarcoidosis were suspected, but surprisingly biopsy revealed progressive multifocal leukoencephalopathy, additionally confirmed by JC-positive PCR in cerebrospinal fluid. Cases of sarcoidosis and progressive multifocal leukoencephalopathy have been reported before. This is the first case of a patient with no sign of active sarcoidosis and without immunosuppressive therapy who recovered spontaneously with a follow-up time of nearly 3 years.

Understanding why patients with schizophrenia do not perceive the hollow-mask illusion using dynamic causal modelling.

Patients suffering from schizophrenia are less susceptible to various visual illusions. For example, healthy participants perceive a hollow mask as a normal face, presumably due to the strength of constraining top-down influences, while patients with schizophrenia do not (Schneider, U., Leweke, F.M., Sternemann, U., Weber, M.M., Emrich, H.M., 1996. Visual 3D illusion: a systems-theoretical approach to psychosis. Eur. Arch. Psychiatry Clin. Neurosci. 246, 256-260; Scheider, U., Borsutzky, M., Seifert, J., Leweke, F.M., Huber, T.J., Rollnik J.D., Emrich, H.M., 2002. Reduced binocular depth inversion in schizophrenic patients. Schizophrenia Research 53, 101-108.; Emrich, H.M., Leweke, F.M., Schneider, U., 1997. Towards a cannabinoid hypothesis of schizophrenia: cognitive impairments due to a dysregulation of the endogenous cannabinoid system. Pharmacol. Biochem. Behav. 56, 803-807). However the neural mechanisms underpinning this effect remain poorly understood. We used functional magnetic resonance imaging to investigate the hollow-mask illusion in schizophrenic patients and healthy controls. The primary aim of this study was to use measures of effective connectivity arising from dynamic causal modelling (DCM) to explain differences in both the perception of the hollow-mask illusion and associated differences in neural responses between patients with schizophrenia and controls, which we hypothesised would be associated with difference in the influences of top-down and bottom-up processes between the groups. Consistent with this explanation, we identified differences between the two groups in effective connectivity. In particular, there was a strengthening of bottom-up processes, and weakening of top-down ones, during the presentation of 'hollow' faces for the patients. In contrast, the controls exhibited a strengthening of top-down processes when perceiving the same stimuli. These findings suggest that schizophrenic patients rely on stimulus-driven processing and are less able to employ conceptually-driven top-down strategies during perception, where incoming sensory data are constrained with reference to a generative model that entails stored information from past experience.

[Cortico-limbic mechanisms of affect regulation in the therapy of depression]. / Zur Rolle kortikolimbischer affektregulatorischer Mechanismen bei der Therapie depressiver Erkrankungen.

Complex functional mechanisms underlie the etiopathogenesis of affective disorders. However, therapeutic implications of new insights are still limited. From the neuropsychological perspective therapy focuses on limbic-cortical (bottom-up) processes whereas cortical-limbic regulatory systems (top-down) were rarely mentioned, although first evidence of their relevance was given in the 80ties, e.g. the use of GABAergic anticonvulsants in affective disorders. Meanwhile modern brain imaging studies support a pronounced role of cortical-limbic top-down mechanisms in the regulation of mood and the therapy of depression, e.g. the effects of cognitive behavioural therapy. The article briefly reviews relevant literature focusing on the neuropsychological hypothesis and the therapeutic implications of these and pharmacologic data. Psychotherapy as well as anticonvulsants appear to mainly affect cortico-limbic mechanisms compared to antidepressants which influence mostly limbic-cortical processes. The combination of both regulatory systems, e.g. the combination of antidepressants and anticonvulsants, appear to have synergistic effects. Such combinations may also be effective in low doses of each compound which does, furthermore, reduce the amount of unwanted side-effects. Studies combining classical antidepressants and mood-stabilizing medication (anticonvulsants and newer neuroleptics) should be performed to substantiate these findings.