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Biomedical subjects

B Opitz

Publications and source records attributed to B Opitz.

At least 37 records · Page 2Linked to original sources
PubMed1998

A new concept for EEG/MEG signal analysis: detection of interacting spatial modes.

We propose a new concept for analyzing EEG/MEG data. The concept is based on a projection of the spatiotemporal signal into the relevant phase space and the interpretation of the brain dynamics in terms of dynamical systems theory. The projection is obtained by a simultaneous determination of spatial modes and coefficients of differential equations. The resulting spatiotemporal model can be characterized by stationary points and corresponding potential field maps. Brain information processing can be interpreted by attraction and repulsion of spatial field distributions given by these stationary points. This allows an objective and quantitative characterization of the brain dynamics. We outline this concept and the underlying algorithm. Results of the application of this method to an event related potential (ERP) study of auditory memory processes are discussed.

Algorithms↗
PubMed1997

Semantic aspects of novelty detection in humans.

The ability to detect unusual and novel events is an important prerequisite for storage of information in memory. Non-tonal novel sounds that deviate from an ongoing auditory environment elicit a positive event-related potential (ERP) component, the so-called novel P3. Though there is converging evidence on the neuronal network engaged in novelty detection, little attention has been paid to the properties of novel sounds, such as their typicality or relationship to mental concepts. Here we report the ERPs evoked by two types of generically novel stimuli, namely identifiable (meaningful) and non-identifiable (non-meaningful) novel sounds. The ERP analysis revealed a novel P3 for both types of sounds. However, when subjects actively attended to the stimuli only identifiable novel sounds evoked a right-lateralized negativity (N4) that peaked shortly after the novel P3. We conclude that novelty detection not only includes the registration of deviancy but also fast access and identification of related semantic concepts.

Adult↗
PubMed1997

Differential effects of communal rearing and preweaning handling on open-field behavior and hot-plate latencies in mice.

On day 2 after delivery, dams of the DBA/1 mouse inbred strain (n = 20/group) with their litter were allocated to one of the following groups: NH21, nonhandling, housed 1 litter/cage, weaned on postnatal day (PND) 21;H21, handling, housed 1 litter/cage, weaned on PND 21; NH30, nonhandling, group-housed (5 litters/cage), weaned on PND 30; H30, handling, group-housed (5 litters/cage), weaned on PND 30. Two male pups of each litter were color marked on PND 2. From PND 8-21 they were removed from their cage, gently held in the experimenter's hand for 5 min/day. The two marked males of each litter were housed together after weaning, and tested in the open-field on PNDs 51-53, and one of each of these siblings was tested for hot-plate latencies on PND 54. Being raised in group-housing and weaned on PND 30 resulted in offspring exhibiting shorter latencies to initiate behavior and higher percentages of centerfield entries in the open field, hot-plate latencies, however, remained unaffected. Preweaning handling increased hot-plate latencies and the number of grooming episodes in the open field, and it decreased defecation, percent centerfield entries and open-field activity in general. It is concluded that the two forms of early experience have different effects on neurobehavioral endpoints 8 weeks after birth.

Animals↗
PubMed1994

[Not Available].

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Germany↗
PubMed1990

[The problem history of the toxin-antitoxin theory in medical microbiology].

The paper presents the history of the toxin-antitoxin theory. It covers the working hypotheses of the pathological-anatomical and clinical research (Virchow and Oertel), the experimental evidence of the diphtheria toxin by Roux and Yersin, up to the discovery of the antitoxin effect by Behring. The differences between an experimental based theory and the speculative conceptions of that time are discussed.

Abrin↗
PubMed1985

An inexpensive apparatus for simultaneous automatic measurement of oxygen consumption in six small laboratory animals.

A closed-circuit system for the simultaneous measurement of oxygen consumption in six small laboratory animals is described. The system consisted of six glass chambers in a big water bath of constant temperature, an oxygen-supply unit, six pressure sensors, a microcomputer and a printer, or, optionally, a desk-top calculator. Ventilation within the chambers provided rapid equilibration of air temperature and humidity conditions. Easily sealing glass lids facilitated operation and maintenance of the system. Carbon dioxide was absorbed inside the chambers by soda lime. At 6-min intervals the consumed oxygen in each chamber was automatically replaced with oxygen from a low-pressure tank. The microcomputer, a self-constructed piece of equipment containing a Z 80 A central processing unit, received pressure data from the separately operating sensors, determined the decrements in chamber pressure due to oxygen consumption by the animal sitting in the chamber, and stored the calculated values in a 2 Kbyte RAM for outprint at the user's request. The apparatus proved to be sensitive, accurate, and easy to operate.

Animals↗