Biomedical subjects

G Juckel

Publications and source records attributed to G Juckel.

45 records · Page 3Linked to original sources

PubMed1995

The Tridimensional Personality Questionnaire and the intensity dependence of auditory evoked dipole source activity.

The relationship between the tridimensional personality questionnaire's (TPQ) dimensions "novelty seeking," "harm avoidance," and "reward dependence" and the intensity dependence of the auditory evoked N1/P2-component was investigated in healthy subjects. Using dipole source analysis, evoked activity of the primary auditory cortex (tangential dipole) could be analyzed at least in part separately from that of secondary auditory areas (radial dipole). It was found that the intensity dependence of the tangential dipole was positively correlated to the TPQ dimension "novelty seeking," but not to "harm avoidance" and "reward dependence." This is in line with findings concerning similar personality traits like "sensation seeking," "impulsivity," or "extraversion." It is therefore concluded that a strong intensity dependence may characterize subjects with an action-oriented and extroverted personality style. The results are discussed within the concept that a low central serotonergic neurotransmission is underlying both an impulsive personality type and a strong intensity dependence of the tangential dipole.

Adult↗

PubMed1995

Antisocial tendencies and cortical sensory-evoked responses in alcoholism.

Alcohol-dependent patients with antisocial, aggressive, and impulsive behaviors form a subgroup, in which a dysfunction of the brain serotonin system is discussed as a pathogenetic factor. Early onset and a transmission from fathers to sons (type II alcoholism; Cloninger, 1987) are supposedly further characteristics of this subgroup. The response pattern of primary auditory cortices to auditory stimuli with different intensities is discussed as a noninvasive indicator of the level of central serotonergic neurotransmission. A strong intensity dependence of these responses is supposed to indicate low serotonergic neurotransmission and vice versa. A strong intensity dependence is therefore expected to characterize patients with antisocial tendencies. Auditory-evoked potentials (N1/P2 component) to stimuli in five different intensities were recorded in 53 hospitalized patients after 1 week of withdrawal. Dipole source analysis was performed to separate responses of primary and secondary auditory cortices. Patients with antisocial tendencies showed a significantly stronger intensity dependence of their evoked responses of primary auditory cortices (tangential dipoles). Age at onset and family history were not related to the intensity dependence of the evoked responses. The results support the notion that alcohol-dependent patients with strong intensity dependence and antisocial tendencies form a subgroup with a serotonergic hypofunction. These patients may respond favorably to a relapse prevention with serotonergic drugs.

Adult↗

PubMed1995

Schizophrenics with small P300: a subgroup with a neurodevelopmental disturbance and a high risk for tardive dyskinesia?

Schizophrenics with a neurodevelopmental disturbance resulting in micro- and macroanatomical cortical abnormalities are supposed to form a subgroup clinically characterized by low premorbid adjustment, early onset, incomplete remission, poor outcome, male predominance and high risk for tardive dyskinesia. A small amplitude of the event-related P3 (P300) potential could be a marker of this subgroup, because the cortical neurons and their orderly laminar arrangement are crucial for the electrogenesis of P3. In a 2-year follow-up study, auditory evoked P3 was recorded in 89 stabilized schizophrenic outpatients. Patients who developed tardive dyskinesia during the follow-up had smaller P3 than matched controls. Furthermore, a small P3 was associated with low premorbid adjustment, pronounced residual symptoms, low relapse rate, and male predominance. These findings indicate that schizophrenic patients with a reduced P3 have a higher risk of developing tardive dyskinesia and correspond clinically to a schizophrenic subgroup with a supposedly neurodevelopmental disturbance.

Adult↗

PubMed1994

Ventricle size and P300 in schizophrenia.

Both ventricular enlargement and reduced P3 amplitudes are consistent findings in schizophrenic patients, suggesting that the two measures reflect a common underlying pathophysiological process in schizophrenia. Investigating 14 stabilized schizophrenic outpatients, a relationship between the size of the lateral ventricles as well as of the third ventricle on CT scans and the auditory event-related P3 amplitude was, however, not found. This negative result suggests that ventricular enlargement and reduced P3 amplitudes in schizophrenics reflect different pathophysiological processes. It is assumed that the P3 amplitude is related rather to abnormalities in the temporal lobe of schizophrenic patients.

Adult↗

PubMed1994

Auditory evoked dipole source activity: indicator of central serotonergic dysfunction in psychiatric patients?

Event-related potentials reflect postsynaptic effects of cortical neurotransmitters and may be useful as indicators of the function of neurochemical systems. Arguments are presented for the hypothesis that the stimulus-intensity dependence of the auditory-evoked N1/P2 component may be a noninvasive indicator of behaviorally relevant aspects of central serotonergic activity. Converging evidence from our own studies as well as from the literature suggest that a pronounced intensity dependence of this component reflects low central serotonergic neurotransmission and vice versa. Dipole source analysis represents an important methodological advance in this context, because N1/P2 subcomponents generated by different cortical structures with different serotonergic innervation can be separated.

Auditory Cortex↗

PubMed1994

Auditory-evoked dipole source activity as indicator of withdrawal severity in alcoholic patients.

The relationship between auditory-evoked potentials and the ethanol withdrawal syndrome was investigated in alcoholic inpatients using dipole source analysis. It was found that the increase in N1/P2 amplitude during withdrawal was positively correlated to the general severity of the withdrawal, but not to single symptoms such as seizures. Monitoring of initial changes in the auditory-evoked N1/P2 amplitude may be of predictive value concerning the withdrawal severity of alcoholic patients.

Adult↗

PubMed1994

Evoked potentials, serotonin, and suicidality.

The link between suicidality and serotonergic dysfunction is a consistent finding in biological psychiatry. In three independent studies we found weak intensity dependence of auditory evoked potentials, which may be related to high serotonergic activity, in psychiatric patients with a history of suicide attempts. This result seems to contradict studies reporting low serotonergic activity in acute suicidal patients. As an explanation for this discrepancy we propose that serotonergic activity may be low only in acute suicidal states, and that high serotonergic activity, as reflected by a weak intensity dependence, may characterize high-risk patients, in whom a transient decrease of serotonergic activity is accompanied by acute suicidality.

Alcoholism↗

PubMed1993

Intensity dependence of auditory evoked potentials as an indicator of central serotonergic neurotransmission: a new hypothesis.

Because of the increasing importance of the central serotonergic neurotransmission for pathogenetic concepts and its role as a target of pharmacotherapeutic interventions in psychiatry, reliable indicators of this system are needed. It is proposed that the stimulus intensity dependence of auditory evoked N1/P2-component, which is probably modulated by cortical serotonergic innervation, may be a useful and noninvasive indicator of behaviorally relevant aspects of serotonergic activity. Converging evidence from our own studies as well as from the literature suggests that a pronounced intensity dependence of auditory evoked N1/P2-component reflects low central serotonergic neurotransmission. Recent findings concerning general functional aspects of the brain serotonin system reveal that this system is well qualified for adjusting individual levels of sensory processing ("set the tone"), especially in the primary auditory cortex in which the N1/P2-component is mainly generated. Dipole source analysis represents an important methodological advance in this context because it allows the separation of N1/P2-subcomponents generated in the primary auditory cortex from those generated in secondary auditory areas.

Arousal↗

PubMedDate not supplied

Superior temporal gyrus and P300 in schizophrenia: a combined ERP/structural magnetic resonance imaging investigation.

Decrement of the auditory P300 component of the event-related potentials (ERP) is a robust finding in schizophrenic patients and seems to be most pronounced in the left temporal region. Structural MRI studies support the hypothesis that regional structural brain differences in this patient group include reduced volume in temporal lobe structures. The aim of the presented study was to investigate the possible gray matter volume reductions in the left posterior superior temporal gyrus (STG) and the P300 reduction and left <right topographic asymmetry in schizophrenic patients. Therefore, in 50 male schizophrenic patients and 50 age- and educational level-matched male controls, auditory ERPs and structural MRI measurements of the gray matter volume of the STG were assessed. In the group of patients, the psychopathological symptom of thought disorder was correlated with the electrode site T3 and underlying gray matter of the left posterior superior temporal gyrus. The subgroup of patients with pronounced negative symptoms was analyzed with respect to ERP and structural MRI measurements. Our data revealed no evidence for a reduction of P300 amplitude or left STG gray matter volume in schizophrenic patients. However, the higher amount of thought disorders was related to a small T3 amplitude. No associations between the electrophysiological and structural measurements could be detected. There were also no significant reductions of ERP and MRI measurements within the subgroup of patients with pronounced negative symptoms.

Adult↗