PubMed Health⌕ Search

Biomedical subjects

G Juckel

Publications and source records attributed to G Juckel.

At least 19 recordsLinked to original sources
PubMed2005

Serotonergic effects of smoking are independent from the human serotonin transporter gene promoter polymorphism: evidence from auditory cortical stimulus processing.

BACKGROUND: Cigarette smoking has been associated with mood enhancing properties and modulating effects on serotonin activity. The loudness dependence (LD) of the auditory-evoked N1/P2-component has been related to serotonergic neurotransmission, i. e. the allelic variants in the promoter of the 5-hydroxytryptamine-transporter (5-HTT) gene (SCL6A4). Moreover, smoking behavior has been associated to the 5-HTT-genotype. It was hypothesized that cigarette smoking modulates the LD and this effect was expected to interact with the 5-HTT-genotype. METHODS: 5-HTT-genotype and LD were determined in 63 healthy smokers and 114 nonsmokers. RESULTS: LD was significantly affected by smoking status (p = 0.008) and 5-HTT-genotype (p = 0.045) but not by smoking*genotype-interaction or daily cigarette consumption. Current smokers exhibited a significantly weaker LD compared to nonsmokers. 5-HTT-genotype showed no significant effect on smoking behavior. DISCUSSION: The results indicate a higher serotonergic activity in smokers as compared to nonsmokers independent of 5-HTT-genotype. Since former smokers and never smokers showed similar LDs, the serotonin enhancing effect of smoking seems to be a characteristic state, which may contribute to the maintenance of smoking behavior.

Acoustic Stimulation↗
PubMed2005

EEG coherence reflects regional corpus callosum area in Alzheimer's disease.

OBJECTIVE: Correlations between corpus callosum size and interhemispheric EEG coherence were investigated as measures of interhemispheric connectivity in patients with Alzheimer's disease. METHODS: 11 patients underwent both magnetic resonance imaging and quantitative electroencephalography to assess corpus callosum size and interhemispheric coherence. For comparison, corpus callosum size was measured in 24 healthy elderly control subjects. RESULTS: Corpus callosum cross sectional area was significantly reduced in Alzheimer patients relative to controls. Posterior interhemispheric coherence (alpha and beta frequencies) correlated significantly with the size of posterior corpus callosum area, and anterior coherence (delta, theta, and alpha frequencies) with the size of anterior corpus callosum area in the Alzheimer patients. CONCLUSION: Region specific correlations between corpus callosum size and EEG coherence suggest that the decline in interhemispheric connectivity in Alzheimer's disease results from a specific loss of cortical association neurones projecting through the corpus callosum.

Aged↗
PubMed2005

Kinematical analysis of emotionally induced facial expressions: a novel tool to investigate hypomimia in patients suffering from depression.

OBJECTIVE: A novel technique for the kinematic analysis of emotionally induced facial expressions was applied to detect subtle mimic dysfunction in patients with depression. METHODS: Using ultrasound markers at certain points on the face, facial movements were exactly measured while subjects watched a witty sketch ("Mr Bean"). Twenty five medicated patients with depression (11 men, 14 women; mean age, 55.8 years; mean total Hamilton Depression Rating Scale score, 17.1) and 25 healthy controls, matched by sex distribution and handedness, were studied. RESULTS: Depressed patients were characterised by abnormally slow velocity at the beginning of laughing and voluntary facial movements, in addition to reduced laughing frequency. A higher severity of symptoms of depression was significantly associated with slow initial velocity of laughing movements of the left mouth angle (r = -0.45). CONCLUSION: The execution of voluntary and non-voluntary facial movements is abnormally slow in depressed patients, reflecting hypomimia. This mimic slowing is closely associated with the severity of depression. The response of depressed patients to emotional stimuli is also abnormally low, but emotional estimation of the stimuli is similar to normals. This pattern parallels the motor-emotional features known from patients with Parkinson's disease.

Adult↗
PubMed2004

Depletion and restoration of endogenous monoamines affects beta-CIT binding to serotonin but not dopamine transporters in non-human primates.

The radioligand [123I]beta-CIT binds to dopamine transporters in striatum and to serotonin transporters in brainstem. Endogenous dopamine or serotonin may compete with radioligand binding at monoamine transporters. We used alpha-methyl-p-tyrosine (AMPT) to block dopamine production and measured [123I]beta-CIT binding before and after endogenous dopamine was restored by IV administration of the dopamine precursor L-dihydroxyphenylalanine (L-DOPA) in rhesus monkeys. P-chlorophenylalanine (pCPA) was used to inhibit serotonin production, and [123I]beta-CIT binding was assessed before and after IV administration of the serotonin precursor 5-hydroxy-L-tryptophan (L-5-HTP) restored endogenous serotonin. Pretreatment with benserazide blocked peripheral decarboxylization in both paradigms. Serotonin restoration measurably displaced [123I]beta-CIT binding to brainstem serotonin transporters but not to striatal dopamine transporters. Restoration of dopamine apparently did not affect [123I] beta-CIT binding to striatal dopamine transporters. However, dopamine restoration reduced radioligand binding to brainstem serotonin transporters, most likely due to dopamine release from serotonin neurons following L-DOPA administration. The higher striatal density of dopamine transporters relative to dopamine concentrations may explain why [123I] beta-CIT displacement by endogenous dopamine was not observed. This study indicates that [123I]beta-CIT binding in brainstem (raphe area) is affected by endogenous serotonin release in vivo and that L-DOPA treatment may cause serotonin neurons in the brainstem to corelease dopamine.

5-Hydroxytryptophan↗
PubMed2004

The neural basis of the P300 potential. Focus on the time-course of the underlying cortical generators.

The locations and time-courses of the neural generators of the event-related P300 potential have been well described using intracranial recordings. However, this invasive method is not adequate for usage in healthy volunteers or psychiatric patients and not all brain regions can be covered well with this approach. With functional MRI, a non-invasive method with high spatial resolution, most of these locations could be found again. However, the time-course of these activations can only be roughly determined with this method, even if an event-related fMRI design has been chosen. Therefore, we have now tried to analyse the time-course of the activations using EEG data providing a better time resolution. We have used Low Resolution Electromagnetic Tomography (LORETA) in the analysis of P300 data (27 electrodes) of healthy volunteers (n = 50) in the time frame 230-480 ms and found mainly the same activations that have been described using intracranial recordings or fMRI, i. e. the inferior parietal lobe/temporo-parietal junction (TPJ), the supplementary motor cortex (SMA) and the anterior cingulate cortex (ACC), the superior temporal gyrus (STG), the insula and the dorsolateral prefrontal cortex. In these selected regions, an analysis of the activation time-courses has been performed.

Acoustic Stimulation↗
PubMed2004

Kinematical analysis of handwriting movements in depressed patients.

OBJECTIVE: Motor disturbances are a relevant aspect of depression. Kinematical analysis of movements can be applied to explore which type of motor dysfunction is associated with depression. We hypothesized that depressed patients draw and write significantly slower than controls and that motor disturbances become more pronounced under bi-manual demands. METHOD: We examined 37 depressed patients and 37 healthy controls using a digitizing graphic tablet and subsequent kinematical analysis of handwriting and rapid drawing movements. RESULTS: Depressed patients performed drawing with significantly less regular velocity than controls (P < 0.001), but normal velocity. Motor differences between patients and controls did not increase under bi-manual demands. Handwriting of patients was abnormally slow (P = 0.04). CONCLUSION: Irregular patterns of velocity peaks in depressed patients point to basal ganglia dysfunction and/or deficient activity of the sensorimotor cortex and the supplementary motor area as a possible substrate of hand-motor disturbances in depression.

Adult↗
PubMed2004

Loudness dependence of primary auditory-cortex-evoked activity as predictor of therapeutic outcome to prophylactic lithium treatment in affective disorders--a retrospective study.

INTRODUCTION: Lithium has been found to be very effective in prophylactic treatment of affective disorders. However, approximately one-third of patients do not respond to this treatment, which does not become apparent until after a year or more of treatment. Therefore, predictors are needed to avoid a long and unsuccessful therapy with risk of severe side effects. Since lithium acts as a serotonin agonist in prophylactic treatment, a predictor of being able to identify patients with low serotonergic activity, who may be responders to lithium, is promising. To determine whether the loudness dependence (LDAEP) of primary, but not of secondary, auditory-cortex-evoked activity, which is inversely related to central serotonergic neurotransmission, could be such a predictor, responders and non-responders to prophylactic lithium treatment were compared. METHODS: Thirty patients with uni- and bipolar affective disorders, who have taken a prophylactic lithium medication continuously for at least 3 years, were included in the study. Patients were classified as responders if they had no hospitalization within the past 3 years. Dipole source analysis allowing us to separate evoked activity of the primary and secondary auditory cortex was used. RESULTS: The LDAEP of the primary, but not of the secondary, auditory cortex was significantly stronger in the responders to the lithium treatment than in the non-responders, implicating low serotonergic function in these patients. DISCUSSION: This finding, which is in line with previous studies, suggests that loudness dependence of primary auditory-cortex-evoked activity could be a clinically relevant predictor of prophylactic treatment with lithium in affective disorders.

Adult↗
PubMed2003

Kinematical analysis of emotionally induced facial expressions in patients with obsessive-compulsive disorder.

UNLABELLED: BACKGROUND; Motor function is deficient in many patients with obsessive-compulsive disorder (OCD), especially in the face. To investigate subtle motor dysfunction, kinematical analysis of emotional facial expressions can be used. Our aim was to investigate facial movements in response to humorous film stimuli in OCD patients. METHOD: Kinematical analysis of facial movements was performed. Ultrasound markers at defined points of the face provided exact measurement of facial movements, while subjects watched a humorous movie ('Mr Bean'). Thirty-four OCD patients (19 male, 15 female; mean (S.D.) age: 35.8 (11.5) years; mean (S.D.) total Y-BOCS score: 25.5 (5.9)) were studied in unmedicated state and after a 10-week treatment with the SSRI sertraline. Thirty-four healthy controls (19 male, 15 female; mean (S.D.) age: 37.5 (13.1) years) were also investigated. RESULTS: At baseline, OCD patients showed significantly slower velocity at the beginning of laughing than healthy controls and a reduced laughing frequency. There was a significant negative correlation between laughing frequency and severity of OCD symptoms. Ten weeks later a significant increase of laughing frequency and initial velocity during laughing was found. CONCLUSIONS: Execution of adequate facial reactions to humour is abnormally slow in OCD patients. Susceptibility of OCD patients with regard to emotional stimuli is less pronounced than in healthy subjects. This phenomenon is closely correlated to OCD symptoms and is state-dependent.

Adult↗
PubMed2003

Molecular brain imaging and the neurobiology and genetics of schizophrenia.

It has been hypothesized that schizophrenia is related to dysfunction in temporolimbic-prefrontal neuronal networks, which is acquired early in an individual's development. After puberty, relatively reduced prefrontal control of striatal dopaminergic neurotransmission may lead to unmodulated striatal dopamine (DA) activity, and the positive symptoms of acute psychosis. Brain imaging studies support the notion of prefrontal dysfunction in schizophrenia and correlated upregulation of presynaptic striatal DA activity. Recent molecular brain imaging studies have combined genetic assessments with a multimodal neuroimaging approach to further refine our understanding of the pathophysiologic architecture of the disorder. We review the literature on functional brain imaging in schizophrenia and discuss genotype effects on core psychotic symptoms. A promising research strategy is the identification of genetic and environmental factors that contribute to intermediate phenotypes such as working memory deficits in schizophrenia. Molecular brain imaging can help to unravel the complex interactions between genes and environment and its association with neuronal network dysfunction in schizophrenia.

Animals↗
PubMed2003

Anhedonia, self-experience in schizophrenia, and implications for treatment.

Anhedonia - the inability to experience pleasure - is a symptom of several psychiatric disorders such as depression, drug and alcohol dependence, but also schizophrenia. The concept of anhedonia played a major role in psychiatric and psychoanalytic explanations of psychotic behavior. The relationship between notions of anhedonia and of mental evolution and regression (in the work of Myerson and Bleuler) is discussed. The non-evolutionist views of Rado and Meehl are described. Then the concept of anhedonia is discussed in relationship to the phenomenological approach of Sass and Parnas, who view anhedonia as one manifestation of a self-disturbance or self-disorder that is fundamental in schizophrenia. Concerning treatment of anhedonia, it was often hypothesized that anhedonia is associated with a dysfunction of the mesolimbic dopaminergic reward system. However, studies in humans and non-human animal models indicate that dysfunction of central dopaminergic neurotransmission interferes with the process of motivation rather than with the ability to experience pleasure; the latter may be more mediated by the opioidergic and serotonergic neurotransmission. Understanding the neurobiological correlates of motivation and pleasure may provide new options to treat anhedonia in patients with schizophrenia.

Animals↗
PubMed2002

Comparison between the analysis of the loudness dependency of the auditory N1/P2 component with LORETA and dipole source analysis in the prediction of treatment response to the selective serotonin reuptake inhibitor citalopram in major depression.

OBJECTIVES: The loudness dependency of the auditory evoked potentials (LDAEP) is used as an indicator of the central serotonergic system and predicts clinical response to serotonin agonists. So far, LDAEP has been typically investigated with dipole source analysis, because with this method the primary and secondary auditory cortex (with a high versus low serotonergic innervation) can be separated at least in parts. METHODS: We have developed a new analysis procedure that uses an MRI probabilistic map of the primary auditory cortex in Talairach space and analyzed the current density in this region of interest with low resolution electromagnetic tomography (LORETA). LORETA is a tomographic localization method that calculates the current density distribution in Talairach space. RESULTS: In a group of patients with major depression (n=15), this new method can predict the response to an selective serotonin reuptake inhibitor (citalopram) at least to the same degree than the traditional dipole source analysis method (P=0.019 vs. P=0.028). The correlation of the improvement in the Hamilton Scale is significant with the LORETA-LDAEP-values (0.56; P=0.031) but not with the dipole source analysis LDAEP-values (0.43; P=0.11). CONCLUSIONS: The new tomographic LDAEP analysis is a promising tool in the analysis of the central serotonergic system.

Adult↗
PubMed2002

Simultaneous ERP and event-related fMRI: focus on the time course of brain activity in target detection.

The event-related P300 potential has been widely used in neurophysiological research. It is usually evoked with an oddball paradigm. One main reason for its broad application in neurophysiological research is the fact that in several brain/mental diseases, such as Alzheimer's disease or schizophrenia, attenuations of the P300 amplitude and latency have been described. However, a precise correlation of the scalp data to the underlying brain regions was not possible, as the correct localization of the generators of scalp-measured electroencephalogram (EEG) data was limited, due to the low spatial resolution of EEG-data. With the availability of modern imaging technologies, functional Magnetic Resonance Imaging (fMRI) in particular, the underlying brain activations could be detected using an oddball task. Although the spatial resolution of fMRI is excellent, the time resolution is restricted. For a comprehensive understanding of the brain activity underlying the P300 paradigm, we have used a combination of EEG and fMRI to get a precise localization and a high-time resolution of the underlying brain activity.

Acoustic Stimulation↗
PubMed2001

Corpus callosum and P300 in schizophrenia.

Functional abnormalities in the interhemispheric transfer via the corpus callosum in schizophrenia may result in filtering problems and information processing problems, which may in turn be related to the synchronization of cortical event-related activity. To explore whether a relationship exists between corpus callosum (CC) size, measured with in-vivo magnetic resonance imaging, and late auditory event-related P300 potentials, 50 patients with schizophrenia as well as 50 healthy controls were examined. The absolute CC size and subregional areas, as well as the CC areas adjusted for total brain volume, were not significantly different between patients with schizophrenia and controls. While no significant group differences were observed for P3a-, P3b-, PSW-amplitudes and P3b-latencies, P3a- and PSW-latencies were significantly prolonged for patients with schizophrenia. Absolute CC total size was significantly correlated with P3b-amplitudes in healthy controls (r=0.29; P=0.044). In patients with schizophrenia, significant correlations were observed between the subregion of the posterior body of the CC and positive slow wave (PSW; r=0.47; P=0.001). P3a-, P3b- and PSW-latencies were not significantly correlated to CC size in either patients with schizophrenia or healthy controls. The results are discussed in terms of the possibility that abnormalities in interhemispheric transfer may underlie the mechanisms of schizophrenia.

Adult↗
PubMed2001

P300 and symptom improvement in schizophrenia.

RATIONALE: A reduced amplitude of the auditory evoked P300 was interpreted as a trait marker of schizophrenia but reports about correlations between schizophrenic psychopathology and P300 amplitude indicate also a state character. OBJECTIVES: To shed light upon these trait and state aspects a longitudinal study was performed to investigate the influence of symptom improvement and atypical neuroleptics on the amplitudes of the P300 and their subcomponents. METHODS: P300 was recorded in 17 schizophrenic patients before and after 4 weeks under either clozapine or olanzapine in a double-blind controlled design. For comparison, 17 age- and sex-matched healthy subjects were investigated. Parietal and frontal P300 subcomponents were investigated separately using dipole source analysis. RESULTS: Schizophrenic patients had smaller parietal (temporo-basal dipole) but not frontal subcomponent amplitudes (temporo-superior dipole) than controls. For the whole sample subcomponent amplitudes did not change over 4 weeks despite clinical improvement but patients with a pronounced improvement of the PANSS positive score showed a slight enhancement of both subcomponents. This was not significant when the P300 amplitude was measured at a single electrode (Pz). No significant difference between clozapine and olanzapine concerning effects on P300 amplitudes were observed. CONCLUSIONS: The results indicate that P300 subcomponents are modulated by changes of positive but not by changes of negative symptoms or different neuroleptics. This result was obvious for P300 subcomponents but not for Pz electrode measurement, which may be due to a higher reliability of the dipole source activity. The results can be integrated into a hypothetical model containing two pathophysiological subgroups of schizophrenia.

Adult↗
PubMed2001

Assessment of handedness using a digitizing tablet: a new method.

The assessment of handedness is of interest in some psychiatric populations, above all in schizophrenic patients, because there may be a relationship between neurodevelopmental, hemispheric damage and psychiatric disease processes (Crow TJ. Schizophrenia Bulletin 1990;16:433-443; Tyler M, Diamond J, Lewis S. Schizophrenia Research 1995;18:37-41). Various methods to assess handedness have been proposed. In order to detect the most precise instrument for the assessment of handedness, two different measures, a questionnaire and a computational procedure for movement analysis, were compared in a group of healthy subjects. The ability of the methods to discriminate not only between the groups of right-handers (n=12) and left-handers (n=23), but also between left-handers trained in school to use the non-dominant right hand ('inconsistent' left-handers; n=11) and those allowed to use their left hand for writing ('consistent' left-handers; n=12) was investigated. For future investigations, our main concern was to determine if one method had superiority over the other. The results revealed that the Edinburgh Handedness Inventory (EHI) distinguishes just as well as the computational method between right-handers and non-right-handers. However, more precise discrimination between the subgroups of 'consistent' and 'inconsistent' left-handers is possible using digitized analysis of hand-motor performance. According to our results handedness should be assessed not only with the EHI, but also with the computer-aided analysis of hand-movements.

Adult↗
PubMed2001

Event-related potentials. Do they reflect central serotonergic neurotransmission and do they predict clinical response to serotonin agonists?

The increasing knowledge concerning anatomical structures and cellular processes underlying event-related potentials (ERP) as well as methodological advances in ERP data analysis (e.g. dipole source analysis) begin to bridge the gap between ERP and neurochemical aspects. Reliable indicators of the serotonin system are urgently needed because of its role in pathophysiology and as target of pharmacotherapeutic interventions in psychiatric disorders. Converging arguments from preclinical and clinical studies support the hypothesis that the loudness dependence of the auditory evoked N1/P2-response (LDAEP) is regulated by the level of central serotonergic neurotransmission. Dipole source analysis represents an important methodological advance in this context, because the two N1/P2-subcomponents, generated by the primary and secondary auditory cortex known to be differentially innervated by serotonergic fibers, can be separated. A pronounced LDAEP of primary auditory cortices is supposed to reflect low central serotonergic neurotransmission, and vice versa. LDAEP is a parameter with potential clinical value since subgroups of patients with a serotonergic dysfunction can be identified and can be treated more specifically. In depressed patients, a significant relationship between strong LDAEP, indicating low serotonergic function, and a favorable response to SSRI has been found. Additionally, there is evidence from several studies with patients with affective disorders implicating a strong LDAEP as a predictor of favorable response to a preventive lithium treatment.

Arousal↗