Matthias Lochmann

The thalamus as the generator and modulator of EEG alpha rhythm: a combined PET/EEG study with lorazepam challenge in humans.

BACKGROUND Purpose of this study was to investigate the functional relationship between electroencephalographic (EEG) alpha power and cerebral glucose metabolism before and after pharmacological alpha suppression by lorazepam. METHODS Ten healthy male volunteers were examined undergoing two F18-fluorodeoxyglucose (18-FDG) positron emission tomography (PET) scans with simultaneous EEG recording: 1x placebo, 1x lorazepam. EEG power spectra were computed by means of Fourier analysis. The PET data were analyzed using SPM99, and the correlations between metabolism and alpha power were calculated for both conditions. RESULTS The comparison lorazepam versus placebo revealed reduced glucose metabolism of the bilateral thalamus and adjacent subthalamic areas, the occipital cortex and temporo-insular areas (P < 0.001). EEG alpha power was reduced in all derivations (P < 0.001). Under placebo, there was a positive correlation between alpha power and metabolism of the bilateral thalamus and the occipital and adjacent parietal cortex (P < 0.001). Under lorazepam, the thalamic and parietal correlations were maintained, whereas the occipital correlation was no longer detectable (P < 0.001). The correlation analysis of the difference lorazepam-placebo showed the alpha power exclusively correlated with the thalamic activity (P < 0.0001). CONCLUSIONS These results support the hypothesis of a close functional relationship between thalamic activity and alpha rhythm in humans mediated by corticothalamic loops which are independent of sensory afferences. The study paradigm could be a promising approach for the investigation of cortico-thalamo-cortical feedback loops in neuropsychiatric diseases.

Prognostic Factors Determining Long-Term Survival in Well-Differentiated Thyroid Cancer: An Analysis of Four Hundred Eighty-Four Patients Undergoing Therapy and Aftercare at the Same Institution

OBJECTIVES Identification of the prognostic factors relevant for long-term survival in differentiated thyroid cancer in a homogenously treated patient cohort in order to allow a better initial risk stratification. METHODS Four hundred eighty-four (358 females/126 males) patients with differentiated thyroid cancer (330 papillary [68.2%]; 154 follicular [31.8%]) were included. Inclusion criteria consisted of treatment with a uniform therapy scheme and continuous aftercare in the same institution. Initial diagnosis was between 1975-1995 (age at diagnosis, 14-84 years, median, 49.7). Tumor stage: pT1, n = 92; pT2, 211; pT3, 58; pT4, 123. Low-risk: <or=pT3 NX M0, 331; high-risk pT4 and/or M1, 153. After thyroidectomy all patients had at least two (131)I therapies (4-month interval; first, 2-4 GBq; second, 3.7-8 GBq). The median follow-up was 7.6 years (range, 0.2-23.9). The role of eight variables as prognostic factors was tested by regression analysis. RESULTS The corrected cause-specific 5-, 10-, and 20-year survival rates in the whole cohort were 0.95, 0.90, 0.83, respectively; for the low risk-category of papillary cancer, 0.99, 0.97, 0.89; for follicular cancer, 0.98, 0.89, 0.89 (difference papillary/follicular p = 0.0004). The cause-specific survival rates in the high-risk category of papillary cancer were 0.89, 0.85, and 0.85; for follicular cancer, 0.88, 0.73 and 0.52 (p = 0.0016). Variables with significant negative influence on survival were distant metastases, persisting elevated human thyroglobulin levels after one (131)I therapy, age greater than 45 and gender in follicular cancer. Locoregional external radiotherapy did not improve survival but was associated with comorbidity. The aggressiveness of the initial operative resection was also not a prognostic factor for survival. pT4 NX M0 patients of our patient cohort did not exert significant differences in long-term survival compared to pT13 NX M0. This was also true for patients older than 45 years, where the 5- and 10-year survival rates for pT4 NX M0 were 0.93 and 0.90. CONCLUSION Our therapy and aftercare strategy results in a high long-term survival rate especially for high-risk patients. In our patient sample radical initial lymph node resection did not extend long-term survival.

Metabolic changes in vestibular and visual cortices in acute vestibular neuritis

Five right‐handed patients with a right‐sided vestibular neuritis were examined twice with fluorodeoxyglucose positron emission tomography while lying supine with eyes closed: once during the acute stage (mean, 6.6 days) and then 3 months later when central vestibular compensation had occurred. Regional cerebral glucose metabolism (rCGM) was significantly increased (p < 0.001 uncorrected) during the acute stage in multisensory vestibular cortical and subcortical areas (parietoinsular vestibular cortex in the posterior insula, posterolateral thalamus, anterior cingulate gyrus [Brodmann area 32/24], pontomesencephalic brainstem, hippocampus). Simultaneously, there was a significant rCGM decrease in the visual (Brodmann area 17 to 19) and somatosensory cortex areas in the postcentral gyrus as well as in parts of the auditory cortex (transverse temporal gyrus). Fluorodeoxyglucose positron emission tomography thus allows imaging of the cortical activation pattern that is induced by unilateral peripheral vestibular loss. It was possible to demonstrate that the central vestibular system including the vestibular cortex exhibits a visual‐vestibular activation–deactivation pattern during the acute stage of vestibular neuritis similar to that in healthy volunteers during unilateral labyrinthine stimulation. Contrary to experimental vestibular stimulation, the activation of the vestibular cortex was not bilateral but was unilateral and contralateral to the right‐sided labyrinthine failure. Ann Neurol 2004

Acute alcohol effects on neuronal and attentional processing: striatal reward system and inhibitory sensory interactions under acute ethanol challenge.

The acute influence of ethanol on cerebral activity induces complex psycho-physiological effects that are considerably more pronounced during acute ethanol influx than during maximal blood alcohol concentration (elimination phase). Despite the psychiatric and forensic relevance of these different ethanol effects, the underlying neuronal mechanisms are still unclear. In total, 20 male healthy volunteers were investigated each with three different experimental conditions in a randomized order using an intravenous ethanol challenge (40 g bolus infusion): during influx phase, elimination phase, and under placebo condition. During and after the ethanol (or placebo) infusion, neuropsychological testing of divided attention for visual and auditory stimuli was performed with subsequent 18-FDG PET acquisition. The PET data were analysed using SPM99. Ethanol influx and elimination phase showed focal activations in the bilateral striatum and frontal cortex and deactivations in the occipital cortex. The comparison of influx phase vs elimination phase revealed activations in the anterior cingulate and right prefrontal cortex, relevant deactivations were found in the left superior temporal cortex including Wernickes area. Neuropsychological testing showed an attentional impairment under ethanol influx compared to ethanol elimination and placebo with an inverse correlation of the attentional performance for auditory stimuli to occipital activity and for visual stimuli to the left temporal (including auditory) cortex. Acute ethanol administration in healthy volunteers stimulates those striatal regions that are considered to have a particular relevance for alcohol craving (‘reward system’). Modality specific reciprocal inhibition of sensory cortex activity seems to be relevant for attentional performance during acute alcohol impact.

High precision hyperfine measurements in Bismuth challenge bound-state strong-field QED

Electrons bound in highly charged heavy ions such as hydrogen-like bismuth 209Bi82+ experience electromagnetic fields that are a million times stronger than in light atoms. Measuring the wavelength of light emitted and absorbed by these ions is therefore a sensitive testing ground for quantum electrodynamical (QED) effects and especially the electron–nucleus interaction under such extreme conditions. However, insufficient knowledge of the nuclear structure has prevented a rigorous test of strong-field QED. Here we present a measurement of the so-called specific difference between the hyperfine splittings in hydrogen-like and lithium-like bismuth 209Bi82+,80+ with a precision that is improved by more than an order of magnitude. Even though this quantity is believed to be largely insensitive to nuclear structure and therefore the most decisive test of QED in the strong magnetic field regime, we find a 7-σ discrepancy compared with the theoretical prediction.

First observation of the ground-state hyperfine transition in 209Bi80+

The long sought after ground-state hyperfine transition in lithium-like bismuth 209Bi80+ was observed for the first time using laser spectroscopy on relativistic ions in the experimental storage ring at the GSI Helmholtz Centre in Darmstadt. Combined with the transition in the corresponding hydrogen-like ion 209Bi82+, it will allow extraction of the specific difference between the two transitions that is unaffected by the magnetic moment distribution in the nucleus and can therefore provide a better test of bound-state QED in extremely strong magnetic fields.

Laser cooling of relativistic heavy-ion beams for FAIR

Laser cooling is a powerful technique to reduce the longitudinal momentum spread of stored relativistic ion beams. Based on successful experiments at the experimental storage ring at GSI in Darmstadt, of which we show some important results in this paper, we present our plans for laser cooling of relativistic ion beams in the future heavy-ion synchrotron SIS100 at the Facility for Antiproton and Ion Research in Darmstadt.

Detection system for forward emitted photons at the Experimental Storage Ring at GSI

A single photon counting system has been developed for efficient detection of forward emitted fluorescence photons at the Experimental Storage Ring (ESR) at GSI. The system employs a movable parabolic mirror with a central slit that can be positioned around the ion beam and a selected low noise photomultiplier for detection of the collected photons. Compared to the previously used system of mirror segments installed inside the ESR the collection efficiency for forward-emitted photons is improved by more than a factor of 5. No adverse effects on the stored ion beam have been observed during operation besides a small drop in the ion current of about 5% during movement of the mirror into the beam position. The new detection system has been used in the LIBELLE experiment at ESR and enabled for the first time the detection of the ground-state hyperfine M1 transition in lithium-like bismuth (209Bi80+) in a laser-spectroscopy measurement.

Corrigendum to “The thalamus as the generator and modulator of EEG alpha rhythm: A combined PET/EEG study with lorazepam challenge in humans” [NeuroImage 22 (2004) 637–644]

Department of Psychiatry, Johannes Gutenberg–University Mainz, 55131 Mainz, GermanyAvailable online 2 May 20061053-8119/

Improved accuracy of in-ring laser spectroscopy by in-situ electron cooler voltage measurement

- see front matter D 2006 Elsevier Inc. All rights reserved.doi:10.1016/j.neuroimage.2006.03.007DOI of original article:10.1016/j.neuroimage.2004.01.047.* Corresponding author. Department of Nuclear Medicine, Johannes Gutenberg–University Mainz, Langenbeckstr. 1, 55131 Mainz, Germany. Fax: +496131 17 2448.E-mail address: schreckenberger@nuklear.klinik.uni-mainz.de (M. Schreckenberger).Available online on ScienceDirect (www.sciencedirect.com).