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Biomedical subjects

R Cammann

Publications and source records attributed to R Cammann.

At least 19 recordsLinked to original sources
PubMed1990

[Magnetoencephalography--current trends].

The review deals with the method of magnet-encephalography. The physical principles and the most important technical conditions to put into practice this method are mentioned. Comparing with the electroencephalography this method shows various advantages, what leads to its intensive use for the localisation of components of evoked potentials, for the magnet-encephalographic record of the brain activity of the human fetus, and for the localisation of epileptic foci in therapy resistant epileptics.

Brain Damage, Chronic↗
PubMed1989

Differentiation of motor activity of normally active and hyperactive boys in schools: some preliminary results.

All non-task-related body movements during school hours were listed in 11 normally active and 12 hyperactive boys. The mean number of movements was 48 +/- 7 per 45 minutes in the normal actives and 79 +/- 16 per 45 minutes in the hyperactives. The rather monotonous increment and decrement of motor activity during the 4-hr registration period was noticed only in hyperactive boys. These results could be a consequence of a circadian rhythm, as there was independence of type of school hours and of teacher personality. The cyclical level of activity in hyperactive boys was sometimes in the range of the normal actives.

Attention Deficit Disorder with Hyperactivity↗
PubMed1987

[Heart rate and visual evoked potentials during figuring arithmetic problems in boys acquired in early childhood with minimal brain damage].

Changes of the pattern reversal EP and heart rate (HR) during calculating were studied on 32 boys with minimal brain damage and a control group (n 27) matched in age, sex and intelligence. The introduction of a reference period and repetition of the calculation period should improve the value of all results and should give simultaneously a first insight in the course of the parameters investigated, during mental loading. Both groups reached the same results in calculating, yet only the brain damaged boys simultaneously showed significant longer latencies of the EP. This result was interpreted as an effect of the higher loading of the damaged subjects. The task-depended increase of the HR was significant in both groups. The HR-level was getting lower with the increasing number of brain damage criteria. The results of intercorrelation between in physiologic parameters and datas of subjective feeling and results of calculating was negative in all cases. These findings were interpreted on the basis of several difficulties to find out clear cut patterns of reaction for different clinical groups.

Arousal↗
PubMed1985

[Effect of psychosocial risks on the maturation of EEG background activity in early childhood brain-damaged children].

Age-dependent changes in EEG activity were assessed in a comparison of EEG recordings taken from 102 children at the ages of 6 and 10 years. Of the 2-to-13-cycle-a-second activity recorded from the left occipital region, the fast alpha frequencies (10 to 13 cycles a second) showed a significant increase at the expense of all slower frequencies. The children were divided into two groups according to whether they had been exposed to a small or large number of biological risks; in the latter group the extent of the increase in fast alpha activity was negatively related to the number of additional psychosocial risks. This effect was even more pronounced in the group of brain-damaged children, where the smallest age-dependent shift in the EEG frequencies was seen in the group with both minimal brain damage and a high psychosocial risk factor. These data suggest that the exposure of children with minimal brain damage to multiple psychosocial risks may lead to a delay in the maturation of the brain that can be detected by neurophysiological methods.

Alpha Rhythm↗
PubMed1985

[Problems in the clinical use of steady state response].

Frequent stimulation induces a state of permanent evoked activity, i.e. the Steady State Response (SSR). An attempt was undertaken to assess the effects of various parameters on the SSR-configuration. 23 boys with normal brains and normal intelligence were studied under constant conditions. Light flashes were delivered in trains of 1 s at a flash repetition rate of 8 c/s. 60 trains were averaged. Three intensities of stimulation (1,2; 0,6; 0,3 Joule) were used. SSR could be observed in 87% of all volunteers (using intensity 1,2 Joule). Independently of the intensities of the stimulation a well-shaped SSR was found after the 3rd or 4th stimulus of the train. Considering the number of deflections four different types of SSR were detectable. There was a slight coherence between the types of SSR and the dominant alpha-frequency. Continuous enhancement of amplitude with increasing stimulus intensity was found only in 50%. Furthermore changing of the SSR-type was found in 5 cases. Taking into account the variability of SSR in healthy probands using of this method for clinical applications on a larger scale remains to be seen.

Cerebral Cortex↗
PubMed1985

[Use of visual evoked potentials in neurology--a review. I].

In 1972, Halliday and co-workers [13] inaugurated the rotary mirror method for producing the visually evoked potential (VEP) by means of pattern reversal. The so-called pattern reversal VEP (PRVEP) is at present frequently obtained by means of a television monitor (TV stimulation) or light-emitting diode system (LED system). Independent of its special advantages and disadvantages, the stimulation by means of these systems as compared to the simple flash stimulation potentials seems to evoke with considerably better reproduceable latency indices, which enables a clearer separation of normal and pathological values. This is in particular true of the P100 component, which is the most prominent part of the VEP. The size of the individual squares of the chess-board pattern, of the whole stimulus field, the brightness and the intensity of the contrasts exert an influence on amplitudes and latencies of the PRVEP. The hitherto lacking standardisation of the recording technique makes it necessary that laboratory develops its own standard values. The domain of the PRVEP at the time being is the demonstration of demyelinising processes in the region of the optical nerve. That is why the PRVEP plays an important role in the diagnosis of multiple sclerosis, especially in subclinical processes and seemingly only spinal symptoms. Extension of the P100 latency, however, are not specific of multiple sclerosis and can also be caused by other lesions of the optical nerve or by a delayed maturing of the neuronal systems generating the VEP.

Blindness↗
PubMed1985

[Use of visual evoked potentials in neurology--a review. II].

Visual potentials evoked by whole-field pattern reversal (PRVEP) are most frequently used for the diagnosis of damage of the optic nerve. Already in monocular whole-field stimulation typical PRVEP findings could also be observed in case of a damage of the visual pathway in its further course (chiasm or lesion of the optic tract). The application of a hemi-field stimulation led to a distinct improvement of the information value with respect to the presence of a damage of the optic chiasm. A reduction of the amplitudes at the beginning of the disease, the subsequent extension of the P100 latency and the disappearance of a response to the stimulus are considered to be typical. In recent time, the combined application of whole- and hemi-field stimulation also in the diagnosis of lesions of the posterior visual pathway (especially in the region of the occipital lobe) has brought about a certain advance. The results still are contradictory in some respects and require further clarification. The introduction of the VEP into clinical practice as a non-invasive neurophysiological method involving hardly any stress has led to a considerable enrichment of clinical diagnostics and one can still expect a strengthening of this position in conjunction with the increasing perfection of the examination technique.

Dominance, Cerebral↗
PubMed1985

[Frequency of the P3 component of the acoustic ERP in children with normal or diminished concentration ability].

The occurrence of the P3 component of the acoustic vertex ERP after an appropriate stimulus was recorded for 27 male children (including 6 with early brain damage) with normal and 37 (including 33 with early brain damage) with below-normal concentration. Both groups had the same mean age and intelligence. A P3 component was found in the case of 18 subjects with normal and 9 with below-normal concentration. The rearrangement of the subjects to give one group with, and one without, brain damage yielded smaller differences. The significant difference (p less than 1%) in the frequencies with which the P3 component occurred, taking the mean concentration into account, leads to the assumption that the internal processing of the stimulus is disturbed in boys with poor concentration.

Arousal↗