Lüder Deecke | Medical University of Vienna (original) (raw)

Papers by Lüder Deecke

Springer eBooks, 1989

In humans, registration of regional cerebral blood flow (rCBF) and electrophysiological recording... more In humans, registration of regional cerebral blood flow (rCBF) and electrophysiological recordings offer the possibility to (a) study directly parameters of brain activity and (b) establish functional-anatomical relations in behavioral tasks. Current trends in imaging of brain functions include the use of scalp-recorded negative DC potential shifts which are time-locked to the performance of cognitive or motor tasks. A reason for utilizing this phenomenon is the notion of the physiological significance of DC potential shifts as recordable from the scalp surface; it has clearly been established that excitatory synaptic currents of cortical neurons generate electrical dipoles that are negative on the surface and positive at depth. The spatial resolution of scalp-recorded DC potential shifts is limited but is, for example, sufficient for separating neuronal activity of circumscribed cortical areas involved in the execution of movements of different parts of the body (Boschert and Deecke 1986). Spatial transformations of EEG recordings (e.g., Laplacian) can offer additional possibilities for estimating current sources contributing to surface-recorded electrical shifts and may help to distinguish different sources underlying these shifts.

Journal of Neurology, Jul 1, 1988

Progressive decline of anterograde memory functions has been increasingly recognized as a frequen... more Progressive decline of anterograde memory functions has been increasingly recognized as a frequent symptom in chronic multiple sclerosis. In order to investigate the brain structures involved, magnetic resonance imaging was performed in 20 patients. Neuropsychological assessment included the WAIS and WMS subtests information, picture completion, similarities, digit span, logical memory, and paired associate learning. All patients with severely impaired memory functions (n = 5) showed bilateral lesions in the medial temporal lobe, whereas in those patients with moderate (n = 10) or no measurable impairment of memory testing (n = 5) either no lesions were seen in the medial temporal lobes or these lesions were restricted to one side. A post hoc cluster analysis strikingly confirmed these results. The differences could not be related to the age of the patients, the disease duration, or the level of education. Extensive lesions in the white matter of the frontal lobes, thinning and lining of the corpus callosum, and bilateral involvement of the anterior cingulate gyrus had no bearing on the neuropsychological results. These findings indicate that bilateral demyelination in the hippocampal regions is the most likely explanation for the impairment of anterograde memory in such patients.

Neuroscience Letters, 1991

Sources of neural activity identified using non-invasive measurements of cerebral magnetic fields... more Sources of neural activity identified using non-invasive measurements of cerebral magnetic fields (magnetoencephalography) were found to confirm the somatotopic organization of primary motor cortex for movements of different parts of the body in normal human subjects. Somatotopic maps produced with this technique showed slight differences to the 'classic' homunculus obtained from studies using direct cortical stimulation. These findings indicate that neuromagnetie recordings are capable of localizing cortical activity associated with voluntarily produced movements without the use of external stimulation and provide a new method for studying the functional organization of human motor cortex and its role in voluntary movement.

Experimental Brain Research, Mar 1, 1990

Intensive Care Medicine, Mar 1, 1991

Management of patients presenting with traumatic persistent vegetative state (PVS) calls for exte... more Management of patients presenting with traumatic persistent vegetative state (PVS) calls for extensive resources. The ability to predict whether or not a patient is likely to recover is a critical issue. In 12 patients with PVS admitted consecutively for early rehabilitation after head injury, pattern of brain activity was measured by 99mTc-hexamethyl-propylenamineoxime (99mTc-HM-PAO) brain SPECT (single photon emission computer tomography). All patients were re-investigated after a mean observation period of 3 years. A global reduction of cortical blood flow was a reliable predictor of poor long-term outcome, but the demonstration of only focal deficits did not reliably indicate a favourable outcome. Brain SPECT may help to improve outcome prediction in patients with traumatic PVS.

Journal of Neurology, Mar 1, 1989

Twenty-three patients with a clinical diagnosis of Alzheimer's disease were examined with a set o... more Twenty-three patients with a clinical diagnosis of Alzheimer's disease were examined with a set of neuropsychological tests and with 99mTc-hexamethyl-propyleneamineoxime (HMPAO) single photon emission computed tomography (SPECT). Correlations between test results and indices of regional HMPAO distribution were analysed by multidimensional scaling (MDS). Test results covaried positively with relative H M P A O uptake of frontal, inferior parietal and superior temporal regions but not, or in a negative way, with the remainder of the regions. When only positive correlations were analysed, MDS suggested two dimensions of organization: one was related to a dichotomy between frontal and temporo-parietal regions. The relationship of test results to this dimension was largely consistent with common neuropsychological knowledge. A second, less stringent dimension of organization opposed right and left hemisphere regions. The ordering of test results with respect to this dimension was only partly consistent with what is known about the lateralization of neuropsychological deficits from the study of localized brain lesions. The possibility is considered that these inconsistencies may reflect the effect of disproportionally severe involvement of extended cortical systems which modulates the sequels of localized brain damage.

Experimental Brain Research, Dec 1, 1991

Previous studies by magnetoencephalography (MEG) failed to consistently localize the activity of ... more Previous studies by magnetoencephalography (MEG) failed to consistently localize the activity of the supplementary motor area (SMA) prior to voluntary movements in healthy human subjects. Based on the assumption that the SMA of either hemisphere is active prior to voluntary movements, the negative findings of previous studies could be explained by the hypothesis that magnetic fields of current dipole sources in the two SMAs may cancel each other. The present MEG study was performed in a patient with a complete vascular lesion of the right SMA. In this case it was possible to consistently localize a current dipole source in the intact left SMA starting about 1200 msec prior to the initiation of voluntary movements of the right thumb. Starting at about 600 msec prior to movement onset the assumption of a current dipole source in the left primary motor cortex was needed to account for the observed fields. Measurements of brain potentials were consistent with MEG findings of activity of the left SMA starting about 1200 msec prior to movement onset.

Journal of Head Trauma Rehabilitation, Sep 1, 1993

Thirty six patients (31 male, 5 female) who had suffered severe closed head injury were reexamine... more Thirty six patients (31 male, 5 female) who had suffered severe closed head injury were reexamined at an average of 39-3 (SD 12-8, range 7-66) months after the injury. Behavioural symptoms were measured using the Giessen test. The relatives' reports were used for data analysis to ensure that results were valid. The neurophysical impairment subscale of the Glasgow assessment schedule was completed by two neurologists, and the number connection test was completed by each patient. The adjective mood scale was

Biomedizinische Technik, 2001

Neuroscience Letters, Apr 1, 1991

In early blind mammals, the deprived visual cortex undergoes anatomical and functional alteration... more In early blind mammals, the deprived visual cortex undergoes anatomical and functional alterations. Its functional role was investigated in the early human blind by using patterns of cortical activation as measured by scalp-recorded event-related slow negative DC potential shifts. The blind showed higher occipital negativity than did sighted persons both during a tactile reading task and a non-reading tactile control task. Results point to a possible role for the blind's visual cortex in tactile processes.

International Journal of Psychophysiology, Feb 1, 1993

Springer eBooks, 1990

Volitional movements are preceded by the Bereitschaftspotential (BP: Kornhuber and Deecke 1965) a... more Volitional movements are preceded by the Bereitschaftspotential (BP: Kornhuber and Deecke 1965) and accompanied by sustained negative DC shifts (performance-related, negative DC shifts; Lang et al. 1988).

Neuropsychologia, Feb 1, 1997

According to studies in brain-lesioned patients, the cortical substrate subserving the reading of... more According to studies in brain-lesioned patients, the cortical substrate subserving the reading of digitally presented time displays seems to differ from that of reading analogue displays. While the right hemisphere has been assumed to be important for reading analogue displays, reading digital displays is attributed to the left hemisphere. This study attempts to localize the cortical substrate of reading analogue versus digital time displays in the intact human brain using scalp-recorded event-related slow negative DC potential shifts. In the arithmetic tasks, subjects had to judge whether or not the time conveyed by the last out of three tachistoscopically presented (analogue or digital) slides was the exact difference between the time conveyed by the first and the second slide. In the control condition, subjects only had to attend to (analogue or digital) time displays. With analogue slides, frontolateral recording sites revealed a right hemispheric preponderance of DC shifts measured in the interval between the second and third slide. Anterior temporal recording sites revealed a right hemispheric preponderance only when calculations were performed. By contrast, there was no hemispheric lateralization with digital slides. The arithmetic versus control manipulation modulated waveforms, but did not influence hemispheric laterality.

Springer eBooks, 1993

Negative shifts of the cortical DC potential can be conceived as valid indicators of cortical act... more Negative shifts of the cortical DC potential can be conceived as valid indicators of cortical activity. DC shifts are associated with excitatory post-synaptic potentials which arise in dendritic trees of neurons located in superficial layers of the cortex (Caspers et al., 1980). Although being of neural origin, DC shifts may be mediated to some degree by glial cells which serve as a local buffer for potassium (Bauer, this volume; Laming, this volume) or, in scalp recordings, by regulatory mechanisms of the blood-brain barrier. Surface-recorded DC shifts seem to be more directly linked to neural activity than are, for example, measurements of blood flow and metabolism obtained by PET (Positron Emission Tomography) or SPECT (Single Photon Emission Computerised Tomography). Joint studies of DC shifts and regional cerebral blood flow, as carried out by our group, revealed converging results between those methods but that of DC shifts showed a higher sensitivity to event-related patterns of cortical activity (Lang et al., 1988a; Goldenberg et al., 1989; Uhl et al., 1990a). This has motivated us to use DC shifts for functional localisation.

International Journal of Psychophysiology, Aug 1, 1989

Neuroradiology, Jul 22, 1998

Hämostaseologie, 1986

Zusammenfassung165 von 172 Patienten mit zerebralen Durchblutungsstörungen auf ischämischer Basis... more Zusammenfassung165 von 172 Patienten mit zerebralen Durchblutungsstörungen auf ischämischer Basis wurden nach einem durchschnittlichen Beobachtungszeitraum von 58 Monaten neuerlich klinisch untersucht; 7 Patienten waren nach Reinsulten bereits verstorben.Der Schweregrad der sozialen Beeinträchtigung am Ende des Beobachtungszeitraums wurde semiquantitativ • kategorisiert, allfällige weitere ischämische Ereignisse wurden anamnestisch erfaßt.Um den möglichen Einfluß des Erstmanifestationsalters der zerebrovaskulären Erkrankung auf die Langzeitprognose zu überprüfen, wurden die Ergebnisse von Patienten im Alter von bis zu 40 Jahren mit denen von Patienten im Alter von über 40 Jahren verglichen.Bei den älteren Patienten kam es innerhalb der ersten 12 Monate bzw. auch innerhalb der ersten 3 Jahre nach der Erstmanifestation nicht wesentlich häufiger zu neuerlichen zerebrovaskulären Ereignissen als bei den jüngeren Patienten, allerdings wurden zum Unterschied gegenüber der jüngeren Gruppe v...