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Emission Tomography Study (emission + tomography_study)
Selected AbstractsLevels of ,-Aminobutyric Acid-Benzodiazepine Receptors in Abstinent, Alcohol-Dependent Women: Preliminary Findings From an 123I-Iomazenil Single Photon Emission Tomography StudyALCOHOLISM, Issue 9 2000A. R. Lingford-Hughes Background: Although alcohol dependence in women is an increasing problem, little is known about the effects of alcohol on the female brain. Evidence from a few structural and functional neuroimaging studies suggests that the female brain may be more susceptible than the male brain to the harmful effects of alcohol. However, no in vivo studies of the neuropharmacology of alcohol dependence in women have been carried out. The aim of this preliminary study was to test the hypothesis that alcohol dependence in women is associated with greater reduction in ,-aminobutyric acid (GABA)-benzodiazepine receptor levels than in men with an equivalent drinking history. Methods: We used single photon emission tomography and 123I-iomazenil to label the central GABA-benzodiazepine receptor and to compare semiquantified levels in 9 abstinent alcohol-dependent and 13 control women. These groups were further compared with equivalent male groups from a previous study. Results: There was a trend toward a reduction in GABA-benzodiazepine receptor levels in alcohol-dependent women, but this did not reach significance. These lower levels were seen primarily in the cerebellum, occipital lobes, and parietal cortex (left > right). This was in marked contrast with the pattern of reduction seen in the previous study of male dependence, where significant reductions were seen primarily in the frontal cortex. Conclusions: Due to the semiquantitative analysis performed and the relatively small number of subjects in this study, which resulted in a nonsignificant trend, we can only comment on the differences in the pattern of lower levels of GABA-benzodiazepine receptors seen in alcohol dependence in men and women. Although we are not able to ascertain whether the female brain is more susceptible to the effects of alcohol, it appears that alcohol has a differential effect on the central GABA-benzodiazepine receptors in men and women. Recent animal evidence supports this hypothesis. Future studies should explore whether other neuropharmacological differences exist between men and women in alcohol dependence that could have implications for pharmacotherapy. [source] Differential contributions of the parahippocampal place area and the anterior hippocampus to human memory for scenesHIPPOCAMPUS, Issue 6 2002Stefan Köhler Abstract Past neuroimaging research has identified a parahippocampal place area (PPA) in the posterior medial temporal lobe (MTL), which responds preferentially to visual scenes and plays a role in episodic memory for this class of stimuli. In the present positron emission tomography study, we examined to what extent the functional characteristics of the PPA resemble those of other, more anterior MTL regions across various learning and recognition-memory tasks. We also determined whether the involvement of the PPA in recognition of previously studied scenes is specific to a particular type of scene information. We found that, like the PPA, anterior hippocampal regions showed a novelty response (higher activation for novel than repeated scenes) and a stimulus-related response (higher activation for scenes than objects) during learning, indicating that MTL structures other than the PPA contribute to the encoding of novel stimulus relationships in scenes. However, these anterior hippocampal regions showed no involvement during recognition of either spatial or nonspatial information contained in scenes. The PPA, by contrast, was consistently involved in recognition of all types of scene details, presumably through interactions with co-activated parietal and occipitotemporal cortices. We suggest that MTL contributions from the PPA are sufficient to support recognition of scenes when the task can be based on a perceptually based familiarity process. Hippocampus 2002;12:718,723. © 2002 Wiley-Liss, Inc. [source] Neurobiological basis of behavioral and psychological symptoms in dementia of the Alzheimer typePSYCHIATRY AND CLINICAL NEUROSCIENCES, Issue 6 2000Kazuhiro Shinosaki MD Abstract Recent dementia studies indicate that behavioral and psychological symptoms of dementia (BPSD) are not merely an epiphenomenon of cognitive impairment, but could be attributed to specific biological brain dysfunction. We describe findings from different research modalities related with BPSD (psychopathological, neuropsychological, neurochemical, and psychophysiological strategies), and attempt to reconcile them into the more integrated form. Characteristics of delusions in dementia patients should be studied in more detail from a psychopathological aspect, aiming for the integration of psychopathology and neurobiology. Imperfect integration of memory function and cognitive function, assigned to the limbic systems and association areas, respectively, may result in BPSD. More intimate collaboration of psychopathological and neurobiological study would be fruitful to promote the research in psychological basis of BPSD. Neurochemical studies indicated that density of extracellular tangles and/or PHF-tau protein have relationships with delusion or misidentification. These changes in neurochemical parameters should be the key to understanding the pathogenesis of BPSD. More importantly, neurochemical and psychological study could be linked by the research in psychophysiology. Computer-assisted electroencephalogram analysis suggests that the right posterior hemisphere shows significant age-associated change earlier than the left in the elderly. Cerebral metabolic rate by positron emission tomography study indicates that paralimbic, left medial temporal, and left medial occipital area are involved in pathogenesis of BPSD in some dementia patients. [source] Extrastriatal dopaminergic dysfunction in tourette syndromeANNALS OF NEUROLOGY, Issue 2 2010Thomas D. L. Steeves MD Objective Tourette syndrome (TS) is a neuropsychiatric disorder presenting with tics and a constellation of nonmotor symptoms that includes attention deficit hyperactivity disorder, obsessive,compulsive disorder, and impulse control disorders. Accumulated evidence from pharmacological trials and postmortem analyses suggests that abnormalities of dopaminergic neurotransmission play a key role in the pathogenesis of TS. A substantial body of evidence has also accrued to implicate regions outside the striatum in the generation of tics. Methods We initiated an [11C]FLB 457 positron emission tomography study in conjunction with an amphetamine challenge to evaluate extrastriatal dopamine (DA) D2/D3 receptor binding and DA release in a group of treatment-naive, adult TS patients compared with a group of age- and sex-matched controls. Results At baseline, TS patients showed decreased [11C]FLB 457 binding potentials bilaterally in cortical and subcortical regions outside the striatum, including the cingulate gyrus, middle and superior temporal gyrus, occipital cortex, insula, and thalamus. Amphetamine challenge induced DA release in both control and TS subjects bilaterally in many cortical regions; however, in TS patients, regions of increased DA release were significantly more widespread and extended more anteriorly to involve anterior cingulate and medial frontal gyri. Conversely, and in contrast to healthy controls, no significant DA release was noted in the thalami of TS patients. Interpretation These abnormalities of dopaminergic function localize to brain regions previously implicated in TS and suggest a mechanism for the hyperexcitability of thalamocortical circuits that has been documented in the disorder. ANN NEUROL 2010;67:170,181 [source] | ||||||||||