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Biomedical subjects

I Daum

Publications and source records attributed to I Daum.

At least 19 recordsLinked to original sources
PubMed2007

Theory of mind, humour processing and executive functioning in alcoholism.

AIMS: Alcoholism is associated with cognitive deficits, which have been interpreted in terms of a specific vulnerability of the frontal lobes to the toxic effects of alcohol. While executive functions in alcoholism have been investigated extensively, only little work has been carried out on social cognition. The aim of the present study was to investigate the association between executive functions, theory of mind and humour processing in alcoholism. DESIGN, SETTING, PARTICIPANTS AND MEASUREMENTS: A comprehensive neuropsychological test battery was administered to 29 alcoholic patients (Alc) and 29 healthy controls (HC). The test battery included measurements of affect, general intellectual abilities, executive functions, humour processing and theory of mind. The two groups were comparable with respect to affective variables, IQ, gender and age. FINDINGS AND CONCLUSIONS: Group comparisons revealed cognitive as well as affective humour processing deficits of alcoholics in comparison with HC. The observed impairments were related to theory of mind and executive functions. The deficits may contribute to interpersonal problems and are thus of relevance to rehabilitation.

Adult↗
PubMed2006

Cognitive deficits in narcolepsy.

The aim of the investigations was to explore the nature and the severity of cognitive deficits in narcolepsy patients. In two studies, narcolepsy patients were compared with matched control subjects on a range of attention, memory and executive control tasks. Impairments were only observed on attention and executive function tasks which involved higher demands on inhibition or task management abilities whereas relatively routine memory and attention tasks yielded intact performance in narcolepsy patients. The overall pattern of results indicates an executive control deficit in narcolepsy which might be related to a reduction of available cognitive processing resources because of the need for continuous allocation of resources to monitoring and maintenance of vigilance.

Arousal↗
PubMed2005

Neural substrates of manipulation in visuospatial working memory.

The present study aimed to investigate in humans whether similar neuronal mechanisms underlie the manipulation and active processing of visual and visuospatial stimuli. Simultaneous and successive mental rotation and identity judgment of 2-D matrices and 3-D cube figures were contrasted using functional magnetic resonance imaging (fMRI). Results demonstrate that activation patterns during mental rotation with low working memory demands differ depending on stimulus type (2-D vs. 3-D). Comparison of simultaneous mental rotation of matrices and 3-D cubes resulted in activation of frontal as well as inferior and superior parietal cortices. The opposite contrast (mental rotation of 3-D cubes vs. 2-D matrices) yielded only frontal cortex activation. The findings also yield evidence for converging, overlapping activation patterns for 2-D and 3-D stimuli if working memory demands are increased. Results are discussed within the framework of current working memory models.

Adult↗
PubMed2005

The role of the human thalamus in processing corollary discharge.

Corollary discharge signals play an important role in monitoring self-generated movements to guarantee spatial constancy. Recent work in macaques suggests that the thalamus conveys corollary discharge information of upcoming saccades passing from the superior colliculus to the frontal eye field. The present study aimed to investigate the involvement of the thalamus in humans by assessing the effect of thalamic lesions on the processing of corollary discharge information. Thirteen patients with selective thalamic lesions and 13 healthy age-matched control subjects performed a saccadic double-step task in which retino-spatial dissonance was induced, i.e. the retinal vector of the second target and the movement vector of the second saccade were different. Thus, the subjects could not rely on retinal information alone, but had to use corollary discharge information to correctly perform the second saccade. The amplitudes of first and second saccades were significantly smaller in patients than in controls. Five thalamic lesion patients showed unilateral deficits in using corollary discharge information, as revealed by asymmetries compared with the other patients and controls. Three patients with lateral thalamic lesions including the ventrolateral nucleus (VL) were impaired contralaterally to the side of damage and one patient with a lesion in the mediodorsal thalamus (MD) was impaired ipsilaterally to the lesion. The largest asymmetry was found in a patient with a bilateral thalamic lesion. The results provide evidence for a thalamic involvement in the processing of corollary discharge information in humans, with a potential role of both the VL and MD nuclei.

Adult↗
PubMed2005

[Neurocognitive changes and negative symptoms in schizophrenia].

It is widely recognized that schizophrenic disorders are often associated with impairments of cognitive performance. More recently, disorders of higher cognitive control processes ("executive control functions") have captured the attention of researchers as they can considerably impair patients' abilities to live an independent life. Apart from that, considering the heterogeneity of schizophrenia, there have been attempts to relate psychopathological syndromes to changes in distinct cognitive domains. The present review selectively focuses on evidence associating negative symptoms in schizophrenia with deficient performance in specific executive domains. Neurobiological evidence points to biochemical, structural and functional abnormalities in the frontal cortex and associated fronto-subcortical circuits as a common basis of both schizophrenic negative symptoms and disorders of executive control. In a multitude of neuropsychological studies, an association between negative symptoms and problems in the domains of response inhibition, multitasking, cognitive flexibility, contextual updating, problem solving and verbal fluency has been reported. In some cases, however, the disorganization syndrome but not the negative syndrome has been linked with impaired behaviour in these domains. The inconsistencies might be partly due to the unsatisfactory differentiation between the two symptom complexes. Future research should furthermore consider a more precise differentiation between primary and secondary negative symptoms. Finally, the assessment of executive control functions should be both specific and ecologically valid.

Cognition↗
PubMed2004

Cognitive, but not mood dysfunction develops in multiple sclerosis during 7 years of follow-up.

Long-term development of psychological deficits in disability-free early multiple sclerosis (MS) was evaluated in 27 female patients over a period of 7 years and compared with healthy controls. Physical and cognitive parameters deteriorated significantly but not depression scores. In particular, the self-assessed somatic complaints remained non-similar between patients and controls. This indicates that although depression is clinically relevant and frequent in MS, in contrast to cognition it is not related to physical disease progression.

Adolescent↗
PubMed2004

Differential executive control impairments in early Parkinson's disease.

Investigations concerning cognitive functions in early PD have revealed memory and executive function deficits related to dysfunction of fronto-striatal circuitry. Despite the range of data base, many previous investigations are limited because of methodological questions and inconsistencies. Thus the pattern of executive function impairments in early PD is far from being established. In the present investigation, twenty PD patients in early stages of the disease were compared to control subjects on a comprehensive neuropsychological test battery, aiming to explore their cognitive profile across a range of executive subcomponents. Results revealed impairments with respect to initiation, reasoning and planning. In summary, the present investigation shows that PD is associated with a differential executive impairment pattern which is (partly) related to disease characteristics and affective variables.

Aged↗
PubMed2004

Impact of apomorphine on BOLD signal during movement in normals.

Our group investigated modulatory effects of apomorphine on cerebral activation patterns during finger tapping movements in six healthy right-handed volunteers using an established fMRI protocol. Apomorphine application disclosed a reduction of cerebral activation to the contralateral precentral and postcentral gyrus and ipsilateral cerebellum, with a prominent net reduction of BOLD signal in cerebellar areas. These findings contradict those of similar studies performed on dopaminergic function and Parkinson's disease (PD), which predominantly found augmentation of cerebral activation patterns in normal volunteers and PD patients after dopaminergic stimulation. One conceivable explanation for our singular results would be preferred binding of apomorphine to presynaptic dopaminergic receptors, leading to inhibition of endogenous dopamine release and resultant diminished dopaminergic stimulation, reflected in diminished cerebral activation patterns. These findings warrant future consideration and further investigation of possible central inhibitory effects of dopaminergic therapy in functional imaging studies of the dopaminergic system in general and PD in particular.

Adult↗
PubMed2004

Use of sequence information in associative learning in control subjects and cerebellar patients.

Previous studies of our group have shown that cerebellar patients are impaired in their ability to associate a color and a numeral or two colors with a button push. The aim of the present study was to examine whether control subjects make use of sequence information in visuomotor associative learning tasks and if this ability is impaired in cerebellar patients. A group of eight patients with degenerative cerebellar disease and eight age, sex and IQ matched controls were tested. Subjects had to learn the association between pairs of colored squares and a button push. Two colored squares were shown one after the other in a fixed or random order on a computer screen. Control subjects but not cerebellar patients took advantage of the fixed order information of colored squares in order to improve associative learning. Differences between groups could not be explained by differences in verbal and visuospatial short-term memory, color discrimination, affective state or motor disturbances. Results suggest that impaired sequencing of sensory stimuli may contribute to disorders in visuomotor associative learning in cerebellar patients.

Adult↗
PubMed2003

Frontocentral negativity in electroencephalogram reflects motor response evaluation in humans on correct trials.

Recent results suggest that the error-related negativity (ERN/Ne), a negative scalp potential which has so far been associated with error-related processing, is also found for correct responses. This potential is thought to be generated in the anterior cingulate cortex (ACC). To investigate the functional significance of the ERN/Ne, a modified Continuous Performance Task was used. Data analysis was carried out using conventional averaging techniques as well as source localization with low resolution brain electromagnetic tomography (LORETA). Results showed a pronounced negativity associated with correct responses at a frontocentral electrode position, if an expected second imperative stimulus was not presented. LORETA analysis yielded evidence for a source located within the ACC on such trials. Results suggest that a negative scalp potential may be elicited by errorless responses and yield evidence for an evaluative role of the ACC.

Adolescent↗
PubMed2003

The cerebellum and cognition. Intellectual function in spinocerebellar ataxia type 6 (SCA6).

The aim of this study was to assess cognitive function in patients with spinocerebellar ataxia type 6 (SCA6), an autosomal-dominantly inherited disease leading to a progressive cerebellar syndrome. In contrast to other SCA types, the pathological changes are mostly restricted to the cerebellum. Cognitive function was studied in 12 patients with genetically confirmed SCA6 (mean duration of disease: 9.2 +/- 11.6 years) and 12 age- and IQ-matched controls using a test battery comprising tests for IQ, attention, verbal and visuospatial memory, as well as executive function. While none of the SCA6 subjects had features of general intellectual impairment, only mild deficits in single subtests especially in fronto-executive tasks were observed, but without reaching statistical significance. Thus the current findings do not demonstrate severe cognitive dysfunction in SCA6.

Adult↗
PubMed2003

Cognitive deficits in spinocerebellar ataxia type 1, 2, and 3.

Cognitive impairment was studied in distinct types of spinocerebellar ataxia (SCA): eleven SCA1, 14 SCA2, and 11 SCA3 individuals and 8 age- and IQ- matched controls. All were submitted to a neuropsychological test battery that comprised tests for IQ, attention, executive function, verbal and visuospatial memory. Executive dysfunction was prominent in SCA1 as compared with controls and all other SCA types. Mild deficits of verbal memory were present in SCA1, SCA2 and SCA3. The neuropathological pattern in different SCA types suggests that these cognitive deficits are not likely to be contingent upon cerebellar degeneration but to result from disruption of a cerebrocerebellar circuitry presumably at the pontine level.

Age of Onset↗
PubMed2003

Depressed mood and executive dysfunction in early Parkinson's disease.

OBJECTIVES: Studies on neuropsychological functions in early Parkinson's disease (PD) have reported changes with respect to memory and executive control related to dysfunction of fronto-striatal circuitry. The question has been raised, however, whether these findings are at least partly influenced by depression, which as such can also lead to cognitive impairments that depend on the functional integrity of the prefrontal cortex. MATERIAL AND METHODS: In the present investigation early non-depressed PD patients (NPD), early PD patients with mild depressive symptoms (DPD), patients with primary depression (DEP) and healthy controls (HC) completed a range of neuropsychological tests. RESULTS: Group comparisons revealed impairments of DPD patients in comparison with HC with respect to verbal fluency, short-term memory and concept formation. In addition they showed mild working-memory deficits. CONCLUSIONS: In summary the present results indicate that depressed mood in early PD may exacerbate cognitive impairments. Thus careful assessment of affective variables in PD should be an integral part of the treatment of PD.

Depressive Disorder↗
PubMed2003

Depression and cognitive functioning in alcoholism.

AIMS: Studies on cognitive processes in alcoholism have reported changes with respect to executive functions and memory, which have been interpreted within the context of different neuropsychological models. The aims of the present study were to investigate (1) the validity of these models and (2) the influence of depression on cognitive functioning in alcoholism. DESIGN, SETTING AND PARTICIPANTS: In the present investigation, patients suffering from alcoholism (Alc; n = 30), patients with depression but without alcoholism (Dep; n = 28) and healthy controls (HC; n = 28) were compared on a neuropsychological test battery. MEASUREMENTS: The test battery included measurements of mood, memory and executive functions. The possible cumulative effect of alcohol and depression was analysed by comparison of depressed alcoholic patients (Dalc) and non-depressed alcoholic patients (NDAlc). FINDINGS: Group comparisons revealed impairments of alcoholic patients with respect to response inhibition, reasoning and free recall, irrespective of depression. Priming, short-term memory as well as verbal fluency abilities were unaffected. Depressive patients showed verbal fluency as well as free recall deficits. However, there was no difference in performance between depressed and non-depressed alcoholics. CONCLUSIONS: The specific pattern of neuropsychological deficits of the alcoholic patients supports the frontal lobe hypothesis. The results of the present investigation suggest that these deficits are not generally exacerbated by comorbid depressive symptoms. Further studies, however, are desirable to investigate the relation between executive deficits and depression in alcoholics with evidence of major depression.

Adult↗
PubMed2002

Fear conditioned changes of heart rate in patients with medial cerebellar lesions.

Fear conditioned changes of heart rate and skin conductance responses were investigated in patients with medial cerebellar lesions. A classical conditioning paradigm with a tone as the conditioned stimulus (CS) and an electrical shock as the unconditioned stimulus (US) was tested on five patients with medial cerebellar lesions due to surgery for astrocytoma and five controls. The CS preceded the US by 5900 ms and coterminated with the US. Changes in heart rate and skin conductance responses were obtained as measures for autonomic fear responses. Effects of conditioning were quantified by comparison of the habituation and extinction phases. Controls, but not cerebellar patients, showed a significant decrease of heart rate during fear conditioning. However, there were no significant fear conditioned changes in electrodermal responses in either group. In summary, the medial cerebellum seems to be involved in fear-conditioned bradycardia in humans.

Adolescent↗
PubMed2001

Attentive and preattentive processing in narcolepsy as revealed by event-related potentials (ERPs).

Narcolepsy is a neurological disorder, characterised by excessive daytime sleepiness, sleep attacks, cataplexy and abnormal manifestations of rapid eye movement sleep. Recent studies suggest that neuropsychological impairments in narcolepsy may include memory and attention deficits due to a monoaminergic or cholinergic transmitter dysfunction. To explore the nature of cognitive problems, the P300 and mismatch negativity (MMN) event-related potentials were investigated in narcoleptic patients and matched controls. Narcoleptics showed significantly increased P300 amplitudes relative to controls, especially at frontal recording sites. While control subjects exhibited typically larger MMN over the right than the left hemisphere, in particular at frontal and central electrodes, narcoleptics did not show this asymmetry. These results are interpreted as possible alterations in cognitive preattentive and attentive processing associated with altered functioning of the prefrontal cortex in narcolepsy.

Acoustic Stimulation↗
PubMed2001

Impaired perception of vocal emotions in Parkinson's disease: influence of speech time processing and executive functioning.

Little is known about the underlying dimensions of impaired recognition of emotional prosody that is frequently observed in patients with Parkinson's disease (PD). Because patients with PD also suffer from working memory deficits and impaired time perception, the present study examined the contribution of (a) working memory (frontal executive functioning) and (b) processing of the acoustic parameter speech rate to the perception of emotional prosody in PD. Two acoustic parameters known to be important for emotional classifications (speech duration and pitch variability) were systematically varied in prosodic utterances. Twenty patients with PD and 16 healthy controls (matched for age, sex, and IQ) participated in the study. The findings imply that (1) working memory dysfunctions and perception of emotional prosody are not independent in PD, (2) PD and healthy control subjects perceived vocal emotions categorically along two acoustic manipulation continua, and (3) patients with PD show impairments in processing of speech rate information.

Affect↗