Browsing by Author "Weniger, Godehard"

Background: Amygdala and hippocampus show significant structural abnormalities in major depressive disorder (MDD). Individuals with MDD have difficulties in emotional memory. A relationship between emotional memory deficits and structural abnormalities of amygdala and hippocampus in MDD has been proposed but not shown, yet. Methods: The current study assessed memory for emotional faces in 21 young women with recent-onset MDD and 23 matched control subjects. All subjects underwent structural magnetic resonance imaging (3D-MRI) and a clinical and neuropsychological assessment. Results: Depressive subjects had significantly enlarged amygdala size and significantly reduced hippocampal size compared with controls. Depressive subjects were significantly impaired in leaming emotional facial expressions, with deficits being most pronounced for fearful, surprised and disgusted faces. Depressive subjects with amygdala volumes 1 SD or more above the mean of control subjects showed the strongest impairments. Correlation analyses revealed that larger left amygdala volumes were significantly related to worse memory performance and to higher anxiety scores of depressive subjects. Smaller left hippocampal volumes of depressive subjects were related to higher anxiety scores as well. Limitations: All MDD subjects were taking antidepressant medication at the time of the study. Longitudinal studies are needed to clarify whether the behavioral and/or volumetric abnormalities of MDD subjects can be attributed to medication or MDD or both. Conclusions: It might be speculated that amygdala enlargement in young MDD subjects is correlated with amygdalar overactivation and resolves with antidepressant treatment, as was shown for amygdalar over-activation. (c) 2006 Elsevier B.V. All rights reserved.

Present evidence suggests that schizophrenia is associated with explicit memory deficits, whereas implicit memory seems to be largely preserved. Virtual reality studies on declarative allocentric memory in schizophrenia are rare, and studies on implicit egocentric memory in schizophrenia are lacking. However, virtual realities have a major advantage for the assessment of spatial navigation and memory formation, as computer-simulated first-person environments can simulate navigation in a large-scale space. Twenty-five subjects with recent-onset schizophrenia were compared with 25 healthy matched control subjects on two virtual reality tasks affording the navigation and learning of a virtual park (allocentric memory) and a virtual maze (egocentric memory). Compared with control subjects, schizophrenia subjects were significantly impaired in learning the virtual park. However, schizophrenia subjects were as able as control subjects to learn the virtual maze. Stronger disorganized symptoms of schizophrenia subjects were significantly related to more errors on the virtual maze. It is concluded that egocentric spatial learning adds to the many other implicit cognitive skills being largely preserved in schizophrenia. Possibly, the more global neural network supporting egocentric spatial learning is less affected than the declarative hippocampal memory system in early stages of schizophrenia and may offer opportunities for compensation in the presence of focal deficits. (C) 2008 Elsevier B.V. All rights reserved.

Objective: Trauma-exposed individuals with post-traumatic stress disorder (PTSD) display reduced amygdala and hippocampal size and impaired cognition. However, studies on trauma-exposed individuals with dissociative amnesia (DA) or dissociative identity disorder (DID) are lacking. Method: Twenty-three young women who had experienced severe childhood sexual/physical abuse, diagnosed with DA/DID or PTSD, and 25 healthy control subjects were subjected to 3D structural magnetic resonance imaging of amygdala and hippocampus and a clinical and neuropsychological investigation. Results: Compared with controls, trauma-exposed subjects with PTSD (n = 10) displayed significantly reduced amygdala and hippocampal size and significantly impaired cognition. By contrast, trauma-exposed subjects with DA or DID (n = 13) displayed normal amygdala and hippocampal size and normal cognition. Conclusion: We report for the first time volumetric results in subjects with DA/DID without PTSD as comorbid diagnosis. Our results indicate preserved amygdala and hippocampal size and preserved cognition in subjects with these disorders.

To investigate the role of unilateral amygdala lesions on processing emotions, 22 drug-resistant temporal lobe epilepsy (TLE) subjects (12 with left-sided and ten with right-sided focus) were tested, after anterior temporal lobectomy or selective amygdalo-hippocampectomy on two associative learning tasks containing emotional and neutral facial expressions, respectively. Volumetric lesion analysis was performed on the basis of 3-D MR images. No effects of lesion side were found in TLE subjects. Taken thr extent of amygdala damage into account, an interaction effect could be shown between task (learning of neutral facial expressions versus emotional facial expressions) acid group (subjects with little versus considerable amygdala damage), indicating worse performance of subjects with considerable amygdala damage in learning emotional facial expressions. Subjects with considerable amygdala damage were also significantly impaired in learning emotional facial expressions when compared with control subjects. (C) 2001 Elsevier Science Ltd. All rights reserved.

Blood-based tests for the differential diagnosis of Alzheimer's disease (AD) are under intensive investigation and have shown promising results with regard to A beta 40 and A beta 42 peptide species in incipient AD. Moreover, plasma A beta 40 was suggested as an independent cerebrovascular risk factor candidate. These considerations prompted us to analyse a total of 72 plasma samples in vascular dementias (VAD, n = 15), AD with cerebrovascular disease (AD with CVD, n = 7), AD (n = 15), Parkinson's disease and Parkinson's disease dementia (PD/PDD, n = 20) and 15 patients with depression that served as controls (DC) for distinct plasma amyloid-beta (A beta) peptide patterns. For the analysis of plasma we used immunoprecipitation followed by the quantitative ApSDS-PAGE/immunoblot. For comparison, CSF tau and A beta 1 -42 analyses were performed. The major outcome was an increase in A beta 1-40 in plasma of VAD paralleled by a decrease in the ratio of A beta 1-38/A beta 1-40. The ratio A beta 1-38/A beta-1-40 in plasma enabled contrasts of beyond 85% and 80% for discriminating VAD from DC and all other patients, respectively. In CSF, we confirmed the typical CSF biomarker constellation of increased tau and diminished A beta 1-42 levels for AD. The diagnostic accuracy of plasma A beta 1-38/A beta 1-40 for VAD resembled the accuracy of CSF biomarkers for AD. From the presented results, we consider the ratio of plasma A beta 1-38/ A beta 1-40 peptides to be a blood-based biomarker candidate for VAD.

The authors sought to clarify whether lesions in different parts of the cerebellum result in differential cognitive and affective impairment. Six subjects with cerebellar lesions due to posterior inferior cerebellar artery ( PICA) infarction, five subjects with lesions in the SCA vascular territory, and 11 matched controls were administered a battery of standard neuropsychological tests. PICA lesions but not SCA lesions resulted in cognitive and affective deficits pointing to a dominant role of posterior cerebellar regions in cognitive and affective processing.

The goal of this study was to assess facial affect recognition abilities in subjects with various schizophrenia subtypes and subjects with major depression. A total of six disorganized, 21 paranoid and 18 residual subjects with schizophrenia (DSM-IV criteria) were compared with 21 subjects with major depression (DSM-1V criteria) and 30 matched healthy control subjects. Two experimental tasks requiring the sorting and rating of emotional facial expressions were applied. Disorganized and paranoid subjects showed strong impairments in the sorting of emotional facial expressions. Depressive subjects displayed only minor deficits, and residual subjects were unimpaired. Subjects with disorganized schizophrenia rated emotional facial expressions as more aroused, and depressive subjects rated them as less aroused, than the other study groups. Our study demonstrates strong deficits in facial affect recognition in subjects with schizophrenia and pronounced disorganized or psychotic symptoms. Deficits in facial affect recognition are specific to schizophrenia. They may be considered as a state marker of schizophrenia. (C) 2004 Elsevier Ireland Ltd. All rights reserved.

Present evidence suggests that medial temporal cortices subserve allocentric representation and memory, whereas egocentric representation and memory also depends on parietal association cortices and the striatum. Virtual reality environments have a major advantage for the assessment of spatial navigation and memory formation, as computer-simulated first-person environments can simulate navigation in a large-scale space. Twenty-nine patients with amnestic MCI (aMCI) were compared with 29 healthy matched controls on two virtual reality tasks affording to learn a virtual park (allocentric memory) and a virtual maze (egocentric memory). Participants further received a neuropsychological investigation and MRI volumetry at the time of the assessment. Results indicate that aMCI patients had significantly reduced size of the hippocampus bilaterally and the right-sided precuneus and inferior parietal cortex. aMCI patients were severely impaired learning the virtual park and the virtual maze. Smaller volumes of the right-sided precuneus were related to worse performance on the virtual maze. Participants with striatal lacunar lesions committed more errors than participants without such lesions on the virtual maze but not on the virtual park. aMCI patients later converting to dementia (n = 15) had significantly smaller hippocampal size when compared with non-converters (n = 14). However, both groups did not differ on virtual reality task performance. Our study clearly demonstrates the feasibility of virtual reality technology to study spatial memory deficits of persons with aMCI. Future studies should try to design spatial virtual reality tasks being specific enough to predict conversion from MCI to dementia and conversion from normal to MCI. (C) 2010 Elsevier Ltd. All rights reserved.

Present evidence suggests that medial temporal cortices subserve allocentric representation and memory, whereas egocentric representation and memory mainly depends on inferior and superior parietal cortices. Virtual reality environments have a major advantage for the assessment of spatial navigation and memory formation, as computer-simulated first-person environments can simulate navigation in a large-scale space. However, virtual reality studies on allocentric memory in subjects with cortical lesions are rare, and studies on egocentric memory are lacking. Twenty-four subjects with unilateral parietal cortex lesions due to infarction or intracerebral haemorrhage (14 left-sided, 10 right-sided) were compared with 36 healthy matched control subjects on two virtual reality tasks affording to learn a virtual park (allocentric memory) and a virtual maze (egocentric memory). Subjects further received a comprehensive clinical and neuropsychological investigation, and MRI lesion assessment using T(1), T(2) and FLAIR sequences as well as 3D MRI volumetry at the time of the assessment. Results indicate that left- and right-sided lesioned subjects did not differ on task performance. Compared with control subjects, subjects with parietal cortex lesions were strongly impaired learning the virtual maze. On the other hand, performance of subjects with parietal cortex lesions on the virtual park was entirely normal. Volumes of the right-sided precuneus of lesioned subjects were significantly related to performance on the virtual maze, indicating better performance of subjects with larger volumes. It is concluded that parietal cortices support egocentric navigation and imagination during spatial learning in large-scale environments. (C) 2008 Elsevier Ltd. All rights reserved.

Psychotic symptoms in schizophrenia are related to disturbed self-recognition and to disturbed experience of agency. Possibly, these impairments contribute to first-person large-scale egocentric learning deficits. Sixteen inpatients with schizophrenia and 16 matched healthy comparison subjects underwent functional magnetic resonance imaging (fMRI) while finding their way in a virtual maze. The virtual maze presented a first-person view, lacked any topographical landmarks and afforded egocentric navigation strategies. The participants with schizophrenia showed impaired performance in the virtual maze when compared with controls, and showed a similar but weaker pattern of activity changes during egocentric learning when compared with controls. Especially the activity of task-relevant brain regions (precuneus and posterior cingulate and retrosplenial cortex) differed from that of controls across all trials of the task. Activity increase within the right-sided precuneus was related to worse virtual maze performance and to stronger positive symptoms in participants with schizophrenia. We suggest that psychotic symptoms in schizophrenia are related to aberrant neural activity within the precuneus. Possibly, first-person large-scale egocentric navigation and learning designs may be a feasible tool for the assessment and treatment of cognitive deficits related to self-recognition in patients with schizophrenia.

Present neuroimaging findings suggest two subtypes of trauma response, one characterized predominantly by hyperarousal and intrusions, and the other primarily by dissociative symptoms. The neural underpinnings of these two subtypes need to be better defined. Fourteen women with childhood abuse and the current diagnosis of dissociative amnesia or dissociative identity disorder but without posttraumatic stress disorder (PTSD) and 14 matched healthy comparison subjects underwent functional magnetic resonance imaging (fMRI) while finding their way in a virtual maze. The virtual maze presented a first-person view (egocentric), lacked any topographical landmarks and could be learned only by using egocentric navigation strategies. Participants with dissociative disorders (DD) were not impaired in learning the virtual maze when compared with controls, and showed a similar, although weaker, pattern of activity changes during egocentric learning when compared with controls. Stronger dissociative disorder severity of participants with DD was related to better virtual maze performance, and to stronger activity increase within the cingulate gyrus and the precuneus. Our results add to the present knowledge of preserved attentional and visuospatial mnemonic functioning in individuals with DD. (c) 2012 Elsevier Ireland Ltd. All rights reserved.

Longitudinal studies have failed to find progressive hippocampal size reduction in schizophrenia. However, negative results may have been due to follow-up intervals at disease stages where no significant progressive brain changes occur. Furthermore, only male or mixed gender samples have been studied. Forty-six patients with schizophrenia (23 females) and 46 healthy controls (23 females) underwent three-dimensional structural magnetic resonance imaging of the hippocampus and a clinical investigation. Compared with controls, male but not female participants with schizophrenia displayed hippocampal size reduction. Hippocampal size of female but not male schizophrenia patients was related to disorder duration, indicating smaller hippocampal size in female patients with longer disorder duration. Female schizophrenia patients displayed normal hippocampal size at the onset of disorder, but similarly reduced hippocampal size as male schizophrenia patients after some years of illness had passed. Our results suggest preserved hippocampal size in women with schizophrenia during the first years of illness. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

Background. The symptom domain of inattention in attention deficit/hyperactivity disorder (ADHD) suggests that there are neuropsychological fields of attention in which subjects with ADHD express deficits. However, studies using differentiated neuropsychological attentional tests in ADHD are lacking. Method. A consecutive series of 35 subjects with ADHD aged 9-12 years were assessed on a computer-driven neuropsychological test battery for attentional functions. Their performance was classified according to the data of a normative sample of 187 healthy subjects aged 9-12 years, and compared with the performance of 35 matched healthy control subjects. Results. According to normative data, most ADHD subjects performed on all attentional measures within the normal range. Comparisons with the control group revealed that ADHD subjects reacted faster on all attentional tests, yielding statistical significance for the Go/No go test and the Divided Attention test. They also performed with significantly fewer errors on the Divided Attention test. On the Go/No go test, Visual Scanning test and Attentional Shift test ADHD subjects committed significantly more errors than control subjects. Conclusions. Our results suggest a differential pattern rather than a deficit pattern of attentional functions in ADHD. It is suggested that the more rapid response style of ADHD subjects leads to a more erroneous performance in self-paced attentional tasks and to a better performance in externally paced attentional tasks. However, neuropsychological tests of attention do not contribute to the clinical diagnosis of ADHD.

There has been growing interest in the differential role of medial temporal lobe structures in learning and memory. The goal of the present study was to clarify how lesions of hippocampus, parahippocampal gyrus, and amygdala interfere with associative learning and memory. Thirty subjects with pharmacoresistant medial temporal lobe epilepsy (TLE) and temporal lobe removal were compared with 30 matched healthy control subjects. A set of neuropsychological test measures and an associative learning task requiring the learning and recall of objects and faces were administered. The lesions of hippocampus, parahippocampal gyrus, amygdala, and fusiform gyrus of TLE subjects were determined by three-dimensional magnetic resonance imaging (3-D MRI) volumetric assessment. The results indicate that TLE subjects with combined large hippocampal lesions, large parahippocampal gyrus (i.e., perirhinal/entorhinal) lesions, and large amygdala lesions learned and recalled the associative task significantly worse than control subjects or subjects with small lesions of the hippocampus, parahippocampal gyrus, and amygdala. Regression analysis revealed that larger lesions of the parahippocampal gyrus (i.e., perirhinal/entorhinal cortices) were significantly related to increasing deficits on the task, and that hippocampal and amygdala lesion size did not significantly improve the prediction. Our results suggest that perirhinal and entorhinal cortices may contribute predominantly to the associative learning and recall of objects and faces. (C) 2004 Wiley-Liss, Inc.

Recent research indicates that longstanding temporal lobe epilepsy (TLE) is associated with extratemporal, i.e. parietal cortex damage. We investigated egocentric and allocentric memory by use of first-person large-scale virtual reality environments in patients with TLE. We expected that TLE patients with parietal cortex damage were impaired in the egocentric memory task. Twenty-two TLE patients with hippocampal sclerosis (HS) and 22 TLE patients without HS were compared with 42 healthy matched controls on two virtual reality tasks affording to learn a virtual park (allocentric memory) and a virtual maze (egocentric memory). Participants further received a neuropsychological investigation and MRI volumetry at the time of the assessment. When compared with controls, TLE patients with HS had significantly reduced size of the ipsilateral and contralateral somatosensory cortex (postcentral gyrus). When compared with controls or TLE patients without HS, TLE patients with HS were severely impaired learning the virtual maze. Considering all participants, smaller volumes of the left-sided postcentral gyrus were related to worse performance on the virtual maze. It is concluded that the paradigm of egocentric navigation and learning in first-person large-scale virtual environments may be a suitable tool to indicate significant extratemporal damage in individuals with TLE. (C) 2011 Elsevier B.V. All rights reserved.

individuals with schizophrenia have difficulties in emotional information processing. A relationship between behavioral variables of emotional processing and structural amygdala alterations in schizophrenia has been proposed but not shown, yet. Morphological studies of amygdala size in schizophrenia have yielded inconsistent results. The current study assessed paired associates learning of emotional and neutral faces in 16 subjects with schizophrenia during acute episode and in relative remission after 3 months. Sixteen matched controls were studied for comparison. Subjects also underwent structural magnetic resonance imaging (3D-MRI) at the first time of assessment. Subjects with schizophrenia showed a significant decrease (by 13%) in total size of the amygdala compared to controls, which was more pronounced on the right side. Subjects with schizophrenia improved associative learning of facial identities but not of emotional facial expressions after relative remission of psychotic symptoms. Volume of the right amygdala in subjects with schizophrenia and in controls was significantly related to emotional learning, indicating better learning in subjects with larger amygdala size. Our results indicate that subjects with schizophrenia have a deficit to form associations when emotionally loaded material is used. This deficit seems to be trait-like and independent of disease state. It seems to be linked to size reduction of the right amygdala in schizophrenia. (C) 2004 Elsevier B.V. All rights reserved.

The present study attempts to identify cortical lesion sites associated with deficits in the decoding of emotional facial expressions and with changes of emotional states. A consecutive sample of 68 subjects with lesions caused by microsurgical tumor resection or by intracerebral hemorrhage were compared with 16 clinical and 15 healthy control subjects. A set of neuropsychological test measures - two experimental tasks requiring the sorting and rating of emotional facial expressions, and an adjective checklist as a measure of mood state - were administered. An analysis according to the functional properties of the areas with lesions revealed that subjects with combined lesions of heteromodal and limbic/paralimbic cortices of the right hemisphere showed the strongest deficits in the decoding of emotional facial expressions. In contrast, subjects with lesions of limbic/paralimbic cortices alone, or subjects with lesions of unimodal or primary motor or sensory cortices displayed only minor deficits. Subjects with combined lesions of heteromodal and limbic/paralimbic cortices of the left hemisphere showed the most negative mood states. Our results suggest that heteromodal and limbic/paralimbic, i.e. transmodal cortices may he viewed as 'bottleneck' structures for the decoding of emotional facial expressions and for the modulation of mood states. Lesions of transmodal cortices deprive limbic structures of one of their main sources of input and are therefore likely to produce deficits in various forms of complex human emotional-cognitive behaviors and emotional states.

Background: Lesions of the thalamus interfere with cognitive functions mainly in the area of declarative learning and memory. Little is known about the role the thalamus plays in implicit learning. Objective: To study explicit and implicit learning and memory in subjects with thalamic lesions and to analyze the influence of lesion characteristics on cognitive performance. Methods: The authors studied the performance of 15 subjects with focal thalamic infarction or hemorrhage on a comprehensive neuropsychological test battery focusing on tests of explicit memory and learning of a nondeclarative motor skill. Subjects with thalamic lesions were compared to 15 healthy matched control subjects and to a clinical control group of 22 subjects who had sustained basal ganglia lesions. Results: Subjects with thalamic lesions showed well-preserved intellectual and executive functions but demonstrated deficits on measures of attention and psychomotor speed, explicit memory, and implicit visuomotor sequence learning. Lesion size in the thalamus was clearly related to subjects' long-term explicit memory performance. However, few of the neuropsychological deficits found seemed specific to the long-term neuropsychological outcome of focal thalamic infarctions. Subjects with lesions in the basal ganglia demonstrated similar deficits. Conclusions: Focal subcortical lesions in the thalamus and the basal ganglia lead to a similar profile of neuropsychological deficits. Lesions in the thalamus not only affect declarative memory but also interfere with nondeclarative motor skill learning.

As the amygdala is involved in various aspects of emotional processing, its characterization using neuroimaging modalities, such as functional magnetic resonance imaging (fMRI), is of great interest. However, in fMRI, the amygdala region suffers from susceptibility artifacts that are composed of signal dropouts and image distortions. Various technically demanding approaches to reduce these artifacts have been proposed, and most require alterations beyond a mere change of the acquisition parameters and cannot be easily implemented by the user without changing the MR sequence code. In the present study, we therefore evaluated the impact of simple alterations of the acquisition parameters of a standard gradient-echo echo-planar imaging technique at 3 T composed of echo times (TEs) of 27 and 36 ms as well as section thicknesses of 2 and 4 mm while retaining a section orientation parallel to the intercommissural plane and an in-plane resolution of 2 X 2 mm(2). In contrast to previous studies, we based our evaluation on the resulting activation maps using an emotional stimulation paradigm rather than on MR raw image quality only. Furthermore, we tested the effects of spatial smoothing of the functional raw data in the course of postprocessing using spatial filters of 4 and 8 mm. Regarding MR raw image quality, a TE of 27 ms and 2-mm sections resulted in the least susceptibility artifacts in the anteromedial aspect of the temporal lobe. The emotional stimulation paradigm resulted in robust bilateral amygdala activation for the approaches with 2-mm sections only - but with larger activation volumes for a TE of 36 ms as compared with that of 27 ms. Moderate smoothing with a 4-mm spatial filter represented a good compromise between increased sensitivity and preserved specificity. In summary, we showed that rather than applying advanced modifications of the MR sequence, a simple increase in spatial resolution (i.e., the reduction of section thickness) is sufficient to improve the delectability of amygdala activation. (c) 2008 Elsevier Inc. All rights reserved.