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Biomedical subjects

H Kehr

Publications and source records attributed to H Kehr.

At least 19 recordsLinked to original sources
PubMed1994

Stimulus-specific fast oscillations at zero phase between visual areas V1 and V2 of awake monkey.

Synchronization of fast cortical oscillations (35-90 Hz) has been proposed as a basis of sensory integration. This hypothesis requires stimulus specific oscillations that occur synchronously in different cortical areas of awake animals. Here, we demonstrate the presence of, and phase-locking between, high amplitude stimulus specific oscillations (50-90 Hz) in striate (V1) and extra striate (V2) visual cortex of an awake monkey. Oscillations of multiple unit spikes and local field potentials occurred with an average V1-V2 phase difference near zero. This finding was unexpected because V1 and V2 are thought to be serially arranged in the primate's visual processing stream. However, near zero-phase synchronization among cortical areas might enable fast and effective communication via the many reciprocal cortico-cortical connections for processes such as sensory integration.

Animals↗
PubMed1993

High frequency (60-90 Hz) oscillations in primary visual cortex of awake monkey.

It has been proposed that synchronized oscillations play a key role in perceptual feature linking and sensory integration. This idea was supported by the discovery of strongly synchronized stimulus-specific oscillations in the visual cortex of anaesthetized cats. The 'synchronization hypothesis' was controversial because in the visual cortex of awake monkeys either only weak or no oscillations were found. We have now recorded high amplitude synchronized oscillation at the level of spike activity and local field potential from the primary visual cortex of an awake monkey. The dominant frequencies (70-80 Hz) were considerably higher than those observed previously in cats and monkeys (30-50 Hz). However, stimulus specificities of the oscillations were comparable to and amplitudes even higher than those in cats.

Animals↗
PubMed1979

[Electromagnetic fields and alternating current, do they accelerate bone healing? (author's transl)].

The effects of combined treatment with electromagnetic fields and alternating current according to the method of Kraus is investigated in two groups at bone-nonunions of 21 beagle-dogs. Identical atrophic nonunions of both ulnae are stabilized with plates and treated electrically for eight weeks at one side only, the other side serves as control. The second group gets an additional cancellous bone graft. Qualitative and quantitative evaluation of X-rays and histology of undecalcified bone shows better bone healing in the group with cancellous bone graft on the treated side compared with the control. The first group shows no remarkable differences between both sides, except an increased periosteal bone formation around the active implants.

Animals↗
PubMed1977

[Corrective osteotomies at posttraumatic deformities of the femur (author's transl)].

The importance of the posttraumatic deformities is apart from the aesthetic point of view also due to the "praearthrotic deformity" according to Hackenbroch. Certain cases require operative correction, the indication of which being corresponding to the diagnosis possibilities. On account of examples the technique of osteotomies at the femur has been pointed out which should always be done in combination with a Compressionosteosynthesis.

Adolescent↗