Biomedical subjects

Georg Northoff

Publications and source records attributed to Georg Northoff.

21 records · Page 2Linked to original sources

PubMed2002

GABA-ergic modulation of prefrontal spatio-temporal activation pattern during emotional processing: a combined fMRI/MEG study with placebo and lorazepam.

Various prefrontal cortical regions have been shown to be activated during emotional stimulation, whereas neurochemical mechanisms underlying emotional processing in the prefrontal cortex remain unclear. We therefore investigated the influence of the GABA-A potentiator lorazepam on prefrontal cortical emotional-motor spatio-temporal activation pattern in a combined functional magnetic resonance imaging/magnetoencephalography study. Lorazepam led to the reversal in orbito-frontal activation pattern, a shift of the early magnetic field dipole from the orbito-frontal to medial prefrontal cortex, and alterations in premotor/motor cortical function during negative and positive emotional stimulation. It is concluded that negative emotional processing in the orbito-frontal cortex may be modulated either directly or indirectly by GABA-A receptors. Such a modulation of orbito-frontal cortical emotional function by lorazepam has to be distinguished from its effects on cortical motor function as being independent from the kind of processing either emotional or nonemotional.

Adult↗

PubMed2002

What catatonia can tell us about "top-down modulation": a neuropsychiatric hypothesis.

Differential diagnosis of motor symptoms, for example, akinesia, may be difficult in clinical neuropsychiatry. Symptoms may be either of neurologic origin, for example, Parkinson's disease, or of psychiatric origin, for example, catatonia, leading to a so-called "conflict of paradigms." Despite their different origins, symptoms may appear more or less clinically similar. Possibility of dissociation between origin and clinical appearance may reflect functional brain organisation in general, and cortical-cortical/subcortical relations in particular. It is therefore hypothesized that similarities and differences between Parkinson's disease and catatonia may be accounted for by distinct kinds of modulation between cortico-cortical and cortico-subcortical relations. Catatonia can be characterized by concurrent motor, emotional, and behavioural symptoms. The different symptoms may be accounted for by dysfunction in orbitofrontal-prefrontal/parietal cortical connectivity reflecting "horizontal modulation" of cortico-cortical relation. Furthermore, alteration in "top-down modulation" reflecting "vertical modulation" of caudate and other basal ganglia by GABA-ergic mediated orbitofrontal cortical deficits may account for motor symptoms in catatonia. Parkinson's disease, in contrast, can be characterized by predominant motor symptoms. Motor symptoms may be accounted for by altered "bottom-up modulation" between dopaminergic mediated deficits in striatum and premotor/motor cortex. Clinical similarities between Parkinson's disease and catatonia with respect to akinesia may be related with involvement of the basal ganglia in both disorders. Clinical differences with respect to emotional and behavioural symptoms may be related with involvement of different cortical areas, that is, orbitofrontal/parietal and premotor/motor cortex implying distinct kinds of modulation--"vertical" and "horizontal" modulation, respectively.

Affective Symptoms↗

PubMedDate not supplied

Executive dysfunction, self, and ego pathology in schizophrenia: an exploratory study of neuropsychology and personality.

Schizophrenic patients show a variety of symptoms, including positive and negative symptoms and ego pathology. Their exact underlying neuropsychological mechanisms as well as related changes in personality, however, remain unclear. We therefore conducted an exploratory study to investigate the relationship among neuropsychological functions, various dimensions in personality, and the different kinds of psychopathological symptoms. We investigated 22 paranoid schizophrenic patients and 22 age- and sex-matched healthy controls using a battery of neuropsychological, personality, and psychopathological tests and scales. Neuropsychological tests included executive function, working memory, and episodic memory, whereas personality assessment relied on the Temperament and Character Inventory by Cloninger (Arch Gen Psychiatry. 1987;44:573-88). Psychopathological rating included the scales for the assessment of positive and negative symptoms and the Ego Pathology Inventory by Scharfetter (Psychol Med. 1981;11(2):273-80). Schizophrenic patients showed significant deficits in executive function, working memory, and episodic memory. In contrast to healthy subjects, no significant correlation between working memory and executive function was observed in schizophrenic patients. Instead, both working memory and executive dysfunction were rather related to deficits in retrieval of episodic memory. Positive and negative symptoms correlated with episodic memory deficits but not with any dimension of the personality, whereas ego pathology, in contrast, correlated with executive dysfunction and working memory deficits. Moreover, schizophrenic patients showed specific changes in the self-dimensions of their personality, which correlated significantly with both executive dysfunction and ego pathology. Schizophrenic patients show deficits in working memory and executive function as well as functional dissociation between both. In contrast to positive and negative symptoms, ego pathology in these patients is specifically related to executive dysfunction and alterations in the self-dimension of their personality. It can therefore be concluded that ego pathology must be distinguished from positive and negative symptoms in both underlying neuropsychological dysfunction and predisposing changes in personality.

Adult↗