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Biomedical subjects

B Dubrovsky

Publications and source records attributed to B Dubrovsky.

At least 55 records · Page 3Linked to original sources
PubMed1979

Impairments in limb actions after dorsal funiculi section in cats.

A study of the forces exerted by cats against the ground when jumping from a platform equipped with force transducers, was carried out. The study, complemented by film analysis of the jump, attempted to disclose some of the mechanisms underlying the decrease in efficiency and accuracy in releasing a moving piece of liver observed after dorsal funiculi section above C1 level. The results showed that after the lesion, peak force and height of jump were significantly reduced. However, angle of take-off, an index of force distribution in the three axes of rectangular coordinates remained unchanged. Intact cats consistently extend their forelimbs in a smooth and progressive way toward the liver in order to release it. The distance between the tips of the forelimbs remained more or less constant during the flight. Postoperatively, instead of the regular pattern described, the extension of the limbs was interrupted by fast marked flexion movements and the distance between their tips increased significantly during the flight. Peak extension of the forelimbs was also decreased after surgery. The results are interpreted in terms of the different disruption of the various components (proprio and exteroceptive) that make up fasciculus gracilis and cuneatus of the dorsal funiculi.

Animals↗
PubMed1978

Characteristics of the contingent negative variation in patients suffering from specific phobias.

The essential clinical feature of phobic neurosis is the anticipatory fear of certain objects and situations. Since an important factor in the generation of the contingent negative variation (CNV) is the anticipation of the imperative stimulus, records of CNVs were used as an indicator of electrocortical activity in a group of 14 patients suffering from specific phobias. After clinical evaluation, a CNV to a picture of a nondisturbing object was obtained. The amplitude of the CNV and duration of the PINV (postimperative negative variation) were taken as reference values against which response to the phobic objects were evaluated. Reaction time was automatically measured between the period of S2 and the button press. Significant differences, viz., larger CNV amplitude, longer PINV duration, and shorter reaction time, were found with phobogenic than with nondisturbing stimuli. After behavioral recovery with behavior therapy, no differences were noted in the CNVs obtained with the presentation of non-disturbing and the ones that were phobogenic stimuli. The significance of the results for an understanding of phobic neurosis and behavior therapy are discussed.

Adult↗
PubMed1976

Lateralization of language and spatial functions in left-handed populations.

The level of performance in the execution of a tactual-linguistic task was studied in two left-handed populations, one with language lateralized to the left and the other with language lateralized to the right hemisphere, according to Kimura's dichotic digit test. The results showed that left-handers with speech most likely lateralized to the left hemisphere performed significantly better in the tactual-linguistic task with the left hand, while the ones with speech probably lateralized to the right hemisphere, did better with the right hand. The data suggest that integration of functions asymmetrically represented is facilitated by their differential lateralization.

Adolescent↗
PubMed1976

Effects of changes in carbon dioxide tension in abnormally prolonged contingent negative variation (CNV).

The effects of changes in pCO2 in the development and resolution of normal (return to base line within 2 sec after S2) and abnormal (return to base line in more than 2 sec after S2) CNVs were studied. Decreased pCO2 produced by hyperventilation induced a significant reduction in the duration of the post-imperative negative variation (PINV) without significantly affecting the amplitude of the CNV. Increased pCO2, by inhalation of 5% CO2, on the contrary, produced prolongation of the PINV in two subjects. Control subjects with normal CNVs did not show significant changes in the amplitude or in the duration of the CNV wave when pCO2 was altered. The results are discussed in terms of the possible independence and higher sensitivity to metabolic changes of the PINV brain generators compared with the generators of the CNV wave per se.

Administration, Intranasal↗
PubMed1975

Distribution, metabolism and biological activity of deoxycorticosterone in the central nervous system.

Intravenously injected [1,2-3H]deoxycorticosterone (DOC) readily enters all parts of the central nervous system. In intact and eviscerated rats the highest concentration of radioactive label was recovered from areas corresponding to the reticular formation from the brain stem. In addrenalectomized animals, in addition to high brain stem concentration, there was also a marked increase in the uptake of radioactivity in the septum, hippocampus and pituitary. Data from the eviscerated rat point to a uniform distribution of [1,2-3H]DOC in neural tissues and suggest that the higher levels of radioactivity found in the brain stem may be due to a DOC metabolite with the chromatographic characteristics of allo-tetrahydro-DOC, an anaesthetic-type steroid. A decrease in the amplitude of evoked sciatic potentials in brain stem sites but not in the thalamic relay nucleus was observed in 52% of the cases studied, following the i.v. injection of 100-150 mug DOC.

Adrenalectomy↗