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U Mitzdorf

Publications and source records attributed to U Mitzdorf.

14 recordsLinked to original sources
PubMed1999

Why do patients seek treatment in hospitals of complementary medicine?

OBJECTIVE: This exploratory study evaluated patients' reasons for entering a complementary (alternative) medicine hospital by ranking 15 medical and psychosocial factors that were thought to influence this choice. SUBJECTS AND OUTCOME MEASURES: Two hundred patients (200) from two complementary hospitals, one focusing on Traditional Chinese Medicine and one on the Western type of complementary medicine, completed an extensive questionnaire at the beginning of their inpatient treatment. The questionnaire covered personal background; disease parameters; attitude towards conventional medicine; previous experience with, and knowledge of, complementary therapies; expectations concerning the forthcoming treatment; health-related habits; personality traits; and social support. RESULTS: Optimistic attitudes towards treatment and a positive appraisal of alternative doctors were frequently stated reasons (80%), as was the disease severity (long duration: 86%; acute progression or imminent surgery: 70%). Previous successes with complementary therapies, however, ranked relatively low (53%). Negative opinions concerning conventional therapies and conventional doctors' treatments were mentioned by 68% of the patients. Many patients felt themselves to be under considerable psychologic stress (74%). A majority (73%) was well informed about complementary therapies, and 65% were curious about the forthcoming therapies. Sixty-eight percent (68%) indicated good health behaviors. Fewer patients mentioned contemplative and/or religious attitudes (44%) or lack of social support (25%). Age primarily accounted for variations in the ranking weights of the two subgroups. The specific type of complementary medicine was of minor influence. In 14 out of 21 personality dimensions, the current patient group showed significant deviations from the healthy reference, which is in good agreement with findings from conventionally treated patients.

Adolescent↗
PubMed1994

Mass-action view of single-cell responses to stimulation of the receptive field and/or beyond: exemplification with data from the rabbit primary visual cortex.

Whereas single cells in the visual cortex prefer moving light bars, mass-action responses are evoked better by diffuse luminance changes. This discrepancy was investigated by quantitatively comparing the response properties of individual cells with those of a representative group of cells. The latter responses were derived from the single-cell responses, which were obtained from recording in the rabbit. These quantitative estimates of mean responses resolve the discrepancy between the single-cell domain and the mass-action domain: from the single-cell point of view, a properly oriented moving-bar stimulus is much more effective than a diffuse-light stimulus. The corresponding mass-action response to one common moving-bar stimulus, however, is as small as the mean response to a diffuse-light stimulus (which may even be presented at retinotopically non-corresponding sites). The peak intensities of these mass responses are even much stronger with the diffuse-light stimuli. The same conclusions are valid for the cat, as could be verified from published data. The restrictions of the local receptive field concept that may be implied by the mass-action view of cortical activity and the potential functional relevance of mass activities are discussed.

Animals↗
PubMed1994

Properties of cortical generators of event-related potentials.

Basic properties of cortical ERP generators, as disclosed by recording within the neocortex of mammalian animals and applying the current source-density analysis, are described. It is argued that all cortical generators are most likely caused by excitatory synaptic mass activities. The spatio-temporal pattern of the generators indicates the procedure of information processing, rather than the specific information being processed. It thus represents the physiological analogue of the uniform anatomical structure of the neocortex. Discordant with conclusions from single-cell studies concerning topography, all generators are tangentially widespread. The variations in the basic cortical activation pattern draw attention to the nonspecific central systems as their presumed main causes.

Animals↗
PubMed1987

Properties of the evoked potential generators: current source-density analysis of visually evoked potentials in the cat cortex.

The depth profiles of visually evoked field potentials were recorded in areas 17 and 18 of the cat visual cortex. For comparison, potential profiles evoked by electrical stimulation of the primary afferents and of the nonspecific reticular system were also recorded. From these profiles the current source-density (CSD) distributions were calculated using the one-dimensional CSD method. CSD distributions evoked by the different types of stimuli differ in their amplitudes and time courses by approximately one and two orders of magnitude. Qualitatively, however, they are very similar. Thus, the CSDs can be interpreted as reflecting the same basic pattern of excitatory synaptic activations. This pattern consists of early activation components in the input layers, followed by excitatory synaptic activations in layer III, then in layer II, and in layer V. The basic pattern of cortical activation was found to be modulated by specific features of the visual stimuli. Modulations reflecting contour-versus contrast-contents as well as those reflecting characteristic features of moving patterns have been identified. Most of the CSD components of the cortical activation sequence were obtained from regions extending well beyond the cellular receptive fields in visual cortex. Thus, they reflect nonretinotopic activities. Parameters other than specific features of the visual stimuli have profound influence on cortical CSDs. Nonspecific parameters which have been considered are the general state of cortical excitability, the temporal interactions of successive activities (which are predominantly facilitatory), and the lateral interactions of simultaneous activations from different regions of the visual field (predominantly inhibitory).

Animals↗
PubMed1984

Functional anatomy of the inferior colliculus and the auditory cortex: current source density analyses of click-evoked potentials.

In the auditory midbrain (inferior colliculus) and cortex (superior temporal gyrus) of awake squirrel monkeys profiles of click-evoked field potentials were recorded. The recording tracks were reconstructed anatomically. From the field potentials the one-dimensional current source density (CSD) distributions were calculated. By comparing the CSD profiles with the anatomical features of the reconstructed recording paths, the components of the CSDs could be attributed to certain anatomical sites. Thus a physiological method for the functional identification of recording sites was obtained. It permits the identification of depth locations of specific laminae in cortex. In the inferior colliculus it permits distinction between central and peripheral regions and between three depth segments. The CSDs in the central nucleus of the inferior colliculus lend functional support to the anatomical division into three distinct parts and, in addition, provide the temporal aspects of the main groups of synaptic activities. The CSDs in the auditory cortex permit determination of five different groups of excitatory synaptic activations. The spatio-temporal distributions of these components are very similar to those obtained in other neocortical areas and thus corroborate the hypothesis that afferent activity is relayed very similarly in all sensory areas of neocortex.

Acoustic Stimulation↗
PubMed1980

Monocular activation of visual cortex in normal and monocularly deprived cats: an analysis of evoked potentials.

The unilaterally induced patterns of prominent excitatory post-synaptic activity within Areas 17 and 18 were investigated in normal and monocularly deprived cats. They were elicited by electrical stimulation of the optic nerves and evaluated with the one-dimensional current source-density method. 1. In Area 18 of normal cats the unilaterally and bilaterally induced current source-density patterns closely resemble each other. None of the mono-, di- or tri-synaptic activities is potentiated by binocular convergence. 2. In Area 18 of monocularly deprived cats the synaptic currents elicited by stimulating the nerve on the deprived side lead to approximately the same spatial and temporal distribution of sinks and sources as those induced from the normal eye; but the amplitudes are considerably smaller. This reduction is similar for mono-, di- and trisynaptic responses which indicates (a) that the imbalance between activity from the deprived and non-deprived eye is mainly due to reduced input to the cortical target cells from the deprived eye and (b) that the activity from the deprived eye still relayed to these cells is passed on to supra- and infragranular layers without diminution and in the same way as activity from the normal eye. 3. The imbalance of afferent activity from the deprived and non-deprived eye is apparent in the evoked potentials recorded from the white matter. This indicates that activity from the deprived eye is already strongly reduced in the thalamo-cortical fibres. 4. In monocularly deprived, but not in normal cats the monosynaptic activities from the two eyes are often segregated in depth within layer IV. 5. In Area 17 of both normal and deprived cats only a small fraction of the potential monosynaptic activity can be elicited by electrical stimulation of the optic nerves because of transmission failure in the lateral geniculate nucleus. Comparison of the current source-density patterns elicited from the normal and deprived nerve in monocularly deprived cats indicates that activity produced by fast conducting afferents is more affected (reduced) by deprivation that that conveyed by slower afferents.

Animals↗
PubMed1980

Effects of monocular deprivation in the lateral geniculate nucleus of the cat: an analysis of evoked potentials.

The effects of monocular deprivation on excitatory post-synaptic activity in the lateral geniculate nucleus and on the afferent activity to the geniculate in the cat were examined. Field potentials elicited by electrical stimulation of the optic nerves were recorded and analysed. This approach revealed that the most severe effects of deprivation originate at the input stage to the lateral geniculate nucleus. 1. The membrane currents resulting from excitatory post-synaptic activity in the geniculate are at least a factor of two smaller in amplitude in the deprived than in the non-deprived laminae, indicating a severe reduction of synaptic strength. This effect is equally pronounced for activity mediated by the X- and the Y-system and has to be considered as the major origin of the imbalance of activity from the deprived and non-deprived eye apparent in cortex. 2. Judged from amplitudes and latencies of compound action potentials in the optic tract, afferent Y-activity is not affected by deprivation. This indicates that the number of afferents from the retina of the deprived eye to the geniculates is not significantly reduced by deprivation. 3. During several periods of recording conduction block in the afferents from both eyes was observed.

Animals↗
PubMed1979

Excitatory synaptic ensemble properties in the visual cortex of the macaque monkey: a current source density analysis of electrically evoked potentials.

The spatio-temporal distributions of excitatory synaptic ensemble activities in A17 and A18 of the visual cortex of the macaque monkey have been investigated. The synaptic activities were elicited by electrical stimulation of the primary efferents and were localized by applying the current source density analysis to the intracortically recorded field potentials. The principal results are as follows: 1. In A17, two groups of activity, evoked by fast and slow afferents, respectively, were distinguishable. 2. The fast afferents induced monosynaptic activity in layer IV C alpha and layer VI, disynaptic activity in layer IV C alpha and in the supragranular layers and trisynaptic activity in layer IV B. 3. The slow efferents induced monosynaptic activity in lower layers IV C beta and layer VI, disynaptic activity via strong connections in upper layer IV C beta, further disynaptic activity in layers III and IV B and trisynaptic activity in layers V A and II. 4. With the exception that the CSD data reveal more polysynaptic activity within layer IV, there is good agreement between the spatio-temporal distribution of synaptic activities and the cortical circuit diagrams proposed in anatomical studies. 5. In A18, activities from the slow and fast conducting afferent systems are revealed in layer IV, both most likely mediated by the monosynaptically activated target cells of A17. These activities are passed on to the supra-and infragranular layers. 6. In the lateral geniculate nucleus the safety factor of transmission is higher for activity conveyed by slow-than by fast-conducting retinal afferents. 7. The spatial distribution of monocularly evoked surface potentials failed to reveal the ocular dominance columns. 8. Comparison with the cat indicates that, with respect to the intracortical circuitry and LHN-transmission, there are more similarities between the fast-group activity in the monkey and the y-system in the cat and between the slow-group activity in the monkey and the x-system in the cat than vice versa.

Animals↗
PubMed1978

Prominent excitatory pathways in the cat visual cortex (A 17 and A 18): a current source density analysis of electrically evoked potentials.

The current source density (CSD) method in its one-dimensional approximation is used to analyze the field potentials in visual areas 18 and 17 of the cat, which were elicited by stimulating electrodes in the optic chiasm (OX), the optic radiation (OR) or in the respective cortical area itself. The CSD analysis reveals the basic pattern of excitatory postsynaptic activity. 1. In both visual areas the basic specific excitatory activity flows along three different intracortical pathways, all starting in layer IV: The first pathway relays activity from layer IV to supragranular pyramidal cells via strong, local connections to layer III and from there through long-distance connections to layer II. The second pathway conveys activity from layer IV to layer V, where it mainly contacts apical dendrites of layer VI pyramidal cells. This infragranular polysynaptic activity is not clearly resolvable into separate components, suggesting that it is conveyed by various groups of axons, among them long-distance horizontal connections. The third pathway has one synaptic relay within layer IV and then conveys activity to layer III. In addition, monosynaptic activity is revealed in layers VI and I. 2. In A 18 one coherent, fast-conducting group of afferents induces this basic activity pattern. In A 17 no such fast conducting input is resolvable; the supragranular activity is induced by a small group of afferents with intermediate conduction velocity, which terminate in the upper part of layer IV. The infragranular activity is induced by afferents with slower and widely scattered conduction velocities, which terminate in the lower part of layer IV. The layer VI input is very prominent in A 17 and also has a wide latency scatter. 3. The supragranular activity is more prominent in A 18 than in A 17 and the respective layers appear thicker, in accordance with anatomy. In A 17 the infragranular activity prevails and layers IV and VI appear very broad, again in accordance with anatomy. 4. Comparison of the CSDs with the original evoked potentials shows that the surface evoked potentials over A 18 reflect the three dipolar sink/source distributions of the coherent monosynaptic activity in layer IV and of the two prominent polysynaptic activities in layers III and II. The widely scattered activity in the lower part of layer IV in A 17 and all infragranular activities in both areas generate smaller, partly closed-field potentials; those are not discernible from the strong far-field potentials which originate from the supragranular activity and--especially in A 17--from farther distant events.

Animals↗