Biomedical subjects

Stefanie Brassen

Publications and source records attributed to Stefanie Brassen.

8 recordsLinked to original sources

PubMed2006

Hippocampal-prefrontal encoding activation predicts whether words can be successfully recalled or only recognized.

The main goal of the present fMRI-study was to identify the neural correlates underlying the successful encoding of words which can subsequently be freely recalled or recognized but not recalled. We were particularly interested in common as well as distinct neural substrates of both retrieval modes. To assess qualitatively differently activated brain areas, categorical subsequent memory analyses were applied. In addition, we used linear parametric modulation to detect brain regions associated with "memory-strength". Our findings suggest that the successful verbal encoding of words, which were recognized but not recalled relies on a subset of the regions engaged during successful encoding of freely recalled words. Furthermore, it seems to be dependent on the magnitude of relational binding in a prefrontal-hippocampal circuit whether a word can subsequently be recalled freely or only recognized.

Adult↗

PubMed2006

Combining voxel-based morphometry and diffusion tensor imaging to detect age-related brain changes.

The present study combined optimized voxel-based morphometry and diffusion tensor imaging to detect age-related brain changes. We compared grey matter density maps (grey matter voxel-based morphometry) and white matter fractional anisotropy maps (diffusion tensor imaging-voxel-based morphometry) between two groups of 17 younger and 17 older women. Older women exhibited reduced white matter fractional anisotropy as well as decreased grey matter density most prominently in the frontal, limbic, parietal and temporal lobes. A discriminant analysis identified four frontal and limbic grey and white matter areas that separated the two groups most effectively. We conclude that grey matter voxel-based morphometry and diffusion tensor imaging voxel-based morphometry are well suited for the detection of age-related changes and their combination provides high accuracy when detecting the neural correlates of aging.

Adolescent↗

PubMed2005

Investigation of mood-congruent false and true memory recognition in depression.

The present study investigated the extent of mood-congruent false and true memory recognition in depression. A group of 25 patients with depression and 28 healthy controls completed a variant of the Deese-Roediger McDermott task. Four lists were read to participants in sequence, followed by a recognition task. The words in each list were associated with a central but unmentioned theme word that was either depression-relevant (i.e., loneliness), delusion-relevant (betrayal), positive (holidays), or neutral (window). Whereas it was expected to replicate the conventional mood-congruent effect in depression (better recognition of depression-relevant items), the available literature did not allow strong predictions to be made on the extent of mood-congruent false recognition in depression. Results showed that depressed patients learned emotionally charged material equally well as healthy participants but forgot significantly more neutral material. A conventional mood-congruent memory bias was not found, but relative to healthy controls, patients with depression committed more false recognition errors for emotionally charged words, particularly for depression-relevant items. The results confirm that depressed patients are biased toward emotional material. Reasons for the absence of the expected mood-congruent memory bias are discussed. It is suggested that researchers as well as clinicians should pay more attention to mood-congruent false recollection, because it may undermine the validity of autobiographic reports in depressive patients and may represent a maintenance factor for the disorder.

Adult↗

PubMed2005

Neurocognitive impairment does not predict treatment outcome in obsessive-compulsive disorder.

There is conflicting evidence pertaining to whether or not neurocognitive task performance at baseline predicts treatment response in obsessive-compulsive disorder (OCD). In the present study, we administered a set of executive neurocognitive tests with a putative sensitivity for treatment outcome to a sample of 138 OCD patients. Additionally, subjective neurocognitive dysfunction was determined via a questionnaire. All patients participated in a cognitive-behavioural treatment program (CBT). Results showed that responders (n = 73) did not differ from non-responders (n = 65) on any of the parameters except for decreased performance on the delayed alternation test (p < .1, effect size: .61). A subsidiary analysis revealed that slowing on the Trail-Making Test A and an enhanced rate of perserveration errors on the Wisconsin Card Sorting Test predicted poor outcome for the treatment of compulsions. It is concluded that neurocognitive impairment does not represent a reliable early warning sign for non-response to CBT.

Adult↗

PubMed2005

Long-term behavioural changes after unilateral stereotactic cingulotomy in a case of therapy-resistant alcohol dependence.

We report the case of a female patient who had undergone a unilateral stereotactical anterior cingulotomy (AC) 20 years previously because of refractory alcohol dependence. After AC, the drinking behaviour switched from a chronic to an episodic one with fast losses of control accompanied by abnormal oral impulse-control behaviour. Relapses were stress- but not cue-induced and followed by long-term intervals of abstinence. In addition to an intended lesion of the left dorsal anterior cingulate cortex (ACC), MR images showed additional lesions within the left caudate body and the dorsal medial thalamic nucleus. Applying a neuropsychological test battery, we found disturbed divided attention and impaired executive function. From this, we conclude that the complex lesion pattern may contribute to some of the behavioural changes seen in our patient after AC. This hypothesis is supported by the neuropsychological deficits and the fact that the neuronal circuits, impaired by the lesions, are involved in addiction-specific behaviour. This case report further emphasizes the key role of the ACC and its connections in the maintenance of dependent behaviour.

Aged↗

PubMed2004

Late-onset depression with mild cognitive deficits: electrophysiological evidences for a preclinical dementia syndrome.

Mild cognitive impairment (MCI) is present in up to 60% of patients with late-onset depression and constitutes a major diagnostic problem in geriatric psychiatry. Searching for sensitive markers for the detection of early brain changes suggestive of dementia, we compared this depressive risk population with mildly to moderately demented patients and cognitively unimpaired depressed patients using EEG power and coherence. We found a considerable similarity between Alzheimer's disease patients and cognitively impaired depressed patients regarding the cognitive profile and EEG pattern. Changes in EEG power and coherence at frontotemporal leads in depressive patients with MCI thereby allowed discrimination from cognitively unimpaired patients with a sensitivity of 88% and a specifity of 81%.

Age of Onset↗

PubMed2004

Pedophilia: neuropsychological evidence encouraging a brain network perspective.

Although the vast majority of current pathogenetic theories support a neurobiological understanding of psychiatric disorders, the brain functional correlates of pedophilia are largely unknown. Based on prior behavior genetics research on human sexual orientation and phenomenology as well as the phenotypical intersection of pedophilia with other psychiatric spectrum disorders, we hypothesize the involvement of striato-thalamo-cortical processing loops in the formation of pedophilic urges and behaviors. Data from a current neuropsychological pilot study in four pedophiles encourage our brain functional perspective. As deduced from the network model, all four patients exhibited pronounced and circumscribed deficits in cognitive domains mediated by striato-thalamically controlled areas of the frontal cortex. All patients were especially impaired in neuropsychological functions associated with the prefrontal and motor processing loops (e.g., response inhibition, working memory and cognitive flexibility), with a performance level located up to five standard deviations below the normative data. Contrary to this, neuropsychological performances in cognitive domains without a comparable high frontal loading were in all participants unobtrusive. In future, studying gene by environment interactions in combination with functional neuroimaging and neuropsychological assessment is promising to elucidate the pathophysiological relationship of psychiatric disorders that are characterized by inadequate urges and poor behavioral inhibition.

Adult↗

PubMed2003

Haloperidol challenge in healthy male humans: a functional magnetic resonance imaging study.

Functional magnetic resonance imaging (fMRI) was used to determine the acute blood oxygen level dependent effect (BOLD) of neuroleptic drugs in healthy male subjects. Using a robust simultaneous visuo-acoustic stimulation paradigm fMRI measurements were obtained prior to as well as 1 h and 24 h after intravenous infusion of 5 mg haloperidol to six healthy young men. After the administration, subjects showed significantly reduced BOLD contrast in the middle occipital gyrus while BOLD contrast was increased in the lingual gyrus. This pattern normalised within 24 h. Our results emphasise the necessity to control for interactions through acute medication and confirm fMRI as a non-invasive method for studying cerebral psychopharmacological effects.

Acoustic Stimulation↗