PubMed Health⌕ Search

Biomedical subjects

T Zetzsche

Publications and source records attributed to T Zetzsche.

12 recordsLinked to original sources
PubMed2006

Effects of treatment with the atypical neuroleptic quetiapine on working memory function: a functional MRI follow-up investigation.

BACKGROUND: Working memory as a part of higher-order executive functions is defined by the parallel storage and processing of information. Recent functional fMRI studies have revealed a functional, interregional disintegration of a neuronal network connecting cortical, subcortical and cerebellar regions in schizophrenic patients (SZ). Cognitive impairment in working memory is a core psychopathological correlate of schizophrenic symptoms. Atypical neuroleptics such as quetiapine have shown good efficacy in treating positive and negative symptoms. The presented study evaluated the impact of a neuroleptic steady state treatment with quetiapine on the altered working memory activation patterns in schizophrenia. METHODS: Patients were examined by fMRI at baseline and after 12 weeks of steady state treatment with quetiapine. Matched healthy controls (HC) underwent baseline examination. In the scanner, stimuli were presented in a 2-back and 0-back condition of a working memory (wm) paradigm, whereby a degraded and a non-degraded version were used each time. Additionally, behavioural responses (reaction time to target stimuli and error ratio) were measured. RESULTS: At baseline, healthy controls revealed increased activity in the frontal lobe, especially in regions of the prefrontal cortex. Compared to HC, SZ showed hypoactivation in the right dorsolateral prefrontal cortex (DLPFC) and the ventrolateral prefrontal cortex (VLPFC) bilaterally for the 2-back condition. In the 2-back degraded condition there was a hypoactivation in both, the right DLPFC and the VLPFC. Additionally, patients showed bilaterally decreased activation in the basalganglia in the 2-back and in the right caudatus in the 2-back degraded condition compared to healthy controls. After treatment with quetiapine, patients activations patterns were increased. The pre-post comparison of the 2-back condition revealed a significant increase of activation in the left VLPFC at a significance level of 0.001 (uncorrected). The 2-back degraded condition led to a significant activation pattern in the lingual gyrus and the right precuneus. In both wm conditions, at baseline there were no differences in reaction time but only a worse performance in SZ. After treatment, behavioural measurement of responses, including reaction time and performance, showed slight improvements in SZ, although these did not reach statistical significance. CONCLUSIONS: The neuronal networks underlying working memory are clearly altered in schizophrenia. After 12 weeks of treatment with quetiapine monotherapy, patients showed significant clinical improvement and revealed increased BOLD activity in the VLPFC during a working memory task, although there was no improvement of cognitive performance.

Adult↗
PubMed2006

Plexin B3 is genetically associated with verbal performance and white matter volume in human brain.

The presence of genetic influences on cognitive performance and brain volume is well established. However, specific genetic determinants of the variance of these quantitative traits are not yet known. Plexins act as receptors for semaphorins and are implicated in axon guidance, which is a key process in brain development. We have previously shown that plexin B3 is a highly potent stimulator of neurite outgrowth, which makes its gene PLXNB3 an intriguing candidate gene for traits related to human brain development and cerebral connectivity. We identified several polymorphisms in PLXNB3 predicting changes of amino acids (V598I, E1156D and V1596E) conserved at the corresponding positions of the orthologs in mouse and chimpanzee. PLXNB3 was genotyped in 303 healthy volunteers and 42 male patients with schizophrenia. Cognitive performance was measured with the vocabulary test (Wortschatztest (WST)), a method to estimate roughly general intelligence (g). Brain morphology was characterized by magnetic resonance imaging. Compared to subjects not carrying the modern, human-specific haplotype A, carriers of A scored higher in vocabulary test (WST) irrespective of diagnosis (P=0.0004). This effect could be observed in three independent groups (healthy males: P=0.048; schizophrenic males: P=0.034 and healthy females: P=0.037). Additionally, the haplotype A was associated with increased volume of brain white matter that in turn correlated with performance in the vocabulary test. These findings suggest that plexin B3 may influence cognitive performance, and the development of white matter in vivo in a way similar to its known stimulating effect on neurite outgrowth in vitro. These novel observations warrant further replication in independent samples.

Adult↗
PubMed2005

Thalamic volume in first-episode and chronic schizophrenic subjects: a volumetric MRI study.

OBJECTIVE: The thalamus, as a composite of several functionally very different nuclei, is a major relay and filter station in the CNS and is significantly involved in information processing and gating. The aim of our study is to investigate first-episode and chronic patients and controls to shed light on the potential pathogenetic role of the thalamus in schizophrenia and to assess the relationship between thalamic volumes and psychopathology ratings. METHODS: Forty-three male right-handed chronic and 25 male right-handed first-episode schizophrenic patients treated at the psychiatric hospital of the Ludwig-Maximilians University in Munich and 50 male control subjects were enrolled into the study. Demographic information and current symptom profile of all schizophrenic subjects were assessed using a semistructured interview, including a variety of measures relevant to the study. Volumetry of the thalamic gray and white matter was obtained with 1.5 T MRI, using the BRAINS software application. RESULTS: No significant differences regarding thalamic volumes were detected across groups. However, negative symptoms were significantly correlated with thalamic volumes in first-episode patients, whereas duration of illness and extrapyramidal symptoms were related to thalamic volumes in chronic patients. SUMMARY: Our findings indicate that, while the thalamus might be involved in the pathogenesis of negative symptoms, thalamic volume reduction is not a required element in the pathophysiology of the schizophrenic phenotype.

Adult↗
PubMed2001

In-vivo analysis of the human planum temporale (PT): does the definition of PT borders influence the results with regard to cerebral asymmetry and correlation with handedness?

The aim of our study was to examine whether the degree of planum temporale (PT) asymmetry and the possible correlation of morphological PT asymmetries with handedness are influenced by the definition of PT borders. For this reason, we applied three different anatomical PT definitions formerly used in the literature. The PT total (with the end of the Sylvian fissure (SF) as its posterior border) was separated into anterior and posterior regions. The border between anterior and posterior PT was set according to the following definitions: at the end of Heschl's gyrus (1st definition); at the start of the ascending SF ramus according to the 'knife-cut' method (2nd definition); and at the bifurcation of the SF (3rd definition). Thirty right-handed healthy men were recruited. MRI data sets analyzed with the software program BRAINS were used for in vivo PT volumetry. The Edinburgh Handedness Inventory (EHI) and the Hand Dominance Test were used to determine the degree of handedness. In summary, we detected that the type and the degree of asymmetry between left and right PT were strongly dependent on the definition used for PT borders: a left>right asymmetry was found in all PT regions, except a right>left asymmetry of the anterior PT according to our 1st PT definition (lateral to Heschl's gyrus) and a symmetry of the posterior PT according to our 3rd PT definition (posterior to SF bifurcation). In addition, a significant correlation was found between the degree of handedness measured by the EHI and the right posterior PT (3rd definition). We conclude that the influence of the definition of PT borders on the investigated variables may explain some of the variances between former investigations on PT asymmetry and handedness. The possible implications of the correlation between handedness and the extension of the right parietal PT are discussed and have to be elucidated by further studies.

Adolescent↗
PubMed2000

Adhesio interthalamica in male patients with schizophrenia.

OBJECTIVE: The authors investigated whether absence of the adhesio interthalamica in patients with schizophrenia constitutes a marker of early developmental neuropathological changes. METHOD: Thirty male patients with schizophrenia and 30 healthy male subjects were recruited for study. Magnetic resonance imaging was performed, and the presence or absence of the adhesio interthalamica was determined for each subject. The length and volume of the third ventricle were also measured. RESULTS: No differences in the presence or absence of the adhesio interthalamica were found between patients with schizophrenia and normal comparison subjects. Patients without the adhesio interthalamica had significantly higher scores for negative symptoms than patients with the adhesio interthalamica. There was no correlation between absence of the adhesio interthalamica and length and volume of the third ventricle in either patients or comparison subjects. CONCLUSIONS: The findings suggest that patients with schizophrenia who do not have the adhesio interthalamica are characterized by more severe negative symptoms.

Adolescent↗
PubMed1996

Human intestinal trefoil factor is expressed in human hypothalamus and pituitary: evidence for a novel neuropeptide.

Human intestinal trefoil factor, hITF, a secretory polypeptide found mainly in the human gastrointestinal tract, is a member of the newly characterized trefoil factor or P-domain peptide family representing putative growth factors. Here we describe the identification of this gut peptide in the human brain and pituitary. With reverse transcriptase polymerase chain reaction, we were able to isolate and clone the transcript from human hypothalamus. An antibody generated against a synthetic peptide derived from the carboxyl terminus of hITF was used for immunohistochemical studies of appropriate tissue sections. Neurons expressing hITF were identified in two magnocellular hypothalamic nuclei, the paraventricular and periventricular nuclei. hITF polypeptide was also observed in Herring bodies of the neurohypophysis and in secretory cells of the adenohypophysis. Double immunostaining with antigrowth hormone antibody showed partial coexistence in a selected subpopulation of adenohypophysial cells. Localization of hITF in the hypothalamo-neurohypophysial system may suggest a modulatory action on the classical magnocellular nonapeptides vasopressin and oxytocin, and further indicates an adenohypophysial importance of this peptide. It is likely that hITF represents a novel neuropeptide of yet unknown function.

Adult↗
PubMed1992

Glutamate decarboxylase in developing rat neocortex: does it correlate with the differentiation of GABAergic neurons and synapses?

Postnatal development of glutamate decarboxylase was studied in the rat cerebral cortex. Two methods were used: estimation of the enzymatic activity of glutamate decarboxylase in homogenates of developing cortical tissue and visualization of structures containing glutamate decarboxylase-like immunoreactivity. Glutamate decarboxylase-like immunoreactivity appeared first in perikarya and dendrites and only later in axons and axon varicosities. The most rapid increase in the glutamate decarboxylase activity took place during the second postnatal week and this coincided with a rapid increase in the density of axon varicosities containing glutamate decarboxylase-like immunoreactivity but preceded the most rapid phase in the formation of GABAergic synapses by several days. However, there was a change in the characteristics of glutamate decarboxylase which correlated with GABA synaptogenesis: two fractions of glutamate decarboxylase with different sensitivities to the activating effects of Triton X-100 could be distinguished as from about the time when most of the GABAergic synapses are formed.

Animals↗
PubMed1984

Development of GABAergic neurons in rat visual cortex as identified by glutamate decarboxylase-like immunoreactivity.

The development of glutamate decarboxylase (GAD)-like immunoreactivity was studied in albino rats. GAD-positive structures appeared and accumulated in a characteristic temporo-spatial sequence: from embryonic day 18 onwards in lamina (L) I and subplate; after birth in L I-II, L IV-V and deep L VI including white matter; after two weeks in superficial L I, L II to L III-IV border, L V and L VI-white matter. GAD-positive axon varicosities formed perisomatic 'baskets' on L V pyramids on postnatal day 8 and a few days later on those L II-III. During the third week GAD-positive structures attained adult densities and established different laminar patterns in the primary and secondary visual areas.

Animals↗
PubMedDate not supplied

Superior temporal gyrus and P300 in schizophrenia: a combined ERP/structural magnetic resonance imaging investigation.

Decrement of the auditory P300 component of the event-related potentials (ERP) is a robust finding in schizophrenic patients and seems to be most pronounced in the left temporal region. Structural MRI studies support the hypothesis that regional structural brain differences in this patient group include reduced volume in temporal lobe structures. The aim of the presented study was to investigate the possible gray matter volume reductions in the left posterior superior temporal gyrus (STG) and the P300 reduction and left <right topographic asymmetry in schizophrenic patients. Therefore, in 50 male schizophrenic patients and 50 age- and educational level-matched male controls, auditory ERPs and structural MRI measurements of the gray matter volume of the STG were assessed. In the group of patients, the psychopathological symptom of thought disorder was correlated with the electrode site T3 and underlying gray matter of the left posterior superior temporal gyrus. The subgroup of patients with pronounced negative symptoms was analyzed with respect to ERP and structural MRI measurements. Our data revealed no evidence for a reduction of P300 amplitude or left STG gray matter volume in schizophrenic patients. However, the higher amount of thought disorders was related to a small T3 amplitude. No associations between the electrophysiological and structural measurements could be detected. There were also no significant reductions of ERP and MRI measurements within the subgroup of patients with pronounced negative symptoms.

Adult↗