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At least 199 records · Page 11Linked to original sources
PubMed1989

[Effect of adequate stimulation of the vestibular apparatus on the locomotor activity of the fore- and hindlimb muscles in guinea pigs. Movements relative to the vertical axis].

Influence of the adequate vestibular stimulation on the muscular locomotor activity evoked by stimulation of the mesencephalic locomotor region was investigated in decerebrated guinea pig. Vestibular stimulation was performed by linear sinusoidal shifts along the vertical axis with frequencies of 0.08, 0.2, 0.4, 0.8 Hz, peak accelerations of 0.010, 0.063, 0.252, 1.010 m s-2, respectively. The downward shift was followed by an increase in the activity of fore- and hindlimb extensor muscles observed in the stance phase and by a decrease in the activity of flexor muscles observed in the swing phase of the locomotor cycle. The upward shift was followed by opposite changes in the activity of locomotor muscles. Threshold acceleration that evoked changes in the muscular activity was 0.063 m.s-2, i.e. 0.006 g. Changes in the activity of locomotor muscles lagged input acceleration. Phase lags in the activity of fore- and hindlimb extensor muscles at 0.8 Hz were 63 and 86 degrees, respectively. Changes in the activity of flexor muscles were opposite to those mentioned above and their lags were 264 and 275 degrees, respectively. Vestibular influences on the locomotor activity of muscles are discussed.

Animals↗
PubMed1990

[Pressure wave-induced damage of the vestibular apparatus in guinea pigs. A transmission electron microscopic study].

Guinea pigs were exposed to pressure wave with a peak pressure value of 175.3dB (SPL). Vestibular test and stereoscopic and TEM observations were performed after the exposure. Vestibular function was normal. Within 48 hours of exposure, slight mechanical injuries of the sensory cells in both the creista and macula were observed, such as displacement of the otolithic membrane, distortion and fusion of cilia and protrusion of the cytoplasm. On the 7th and 14th day, these changes became less marked, but a few cells showed swelling of mitochondria and nerve chalice and abnormalities of afferent nerve terminals, which were supposed to be resulted from metabolic disorders. The significance of these changes was discussed.

Animals↗
PubMed1992

Vestibular apparatus disorders after external radiation therapy for head and neck cancers.

External irradiation of different head and neck cancers may involve parts of the ear. The vestibular function of 25 patients in which the inner ear was comprised in the irradiated volume was investigated by electronystagmography (ENG). Doses administered to the vestibular system ranged between 2800 and 5120 cGy. Five patients suffered subjective vertigo or dizziness. Eleven patients (three out of five with vertigo) showed vestibular abnormalities to ENG (44% of the total). Altered responses to specific tests were as follow: six patients to the bithermal caloric stimulation, two to the pendular-sinusoidal test and the other three to both of them. Patients were evaluated 3 and 6 months after the ending of the radiation therapy course. At the first evaluation, abnormalities to caloric test were noted in three patients (12%) and to sinusoidal rotatory test in one patient (4%). At the second evaluation, rates of abnormal response increased to 36% and 20%, respectively. Vestibular disorders seemed to be scantly related to the total radiation dose. Data of literature are discussed in order to identify possible implications on treatment planning.

Adult↗
PubMed1987

[Effect of adequate stimulation of the vestibular apparatus on the locomotor activity of the muscles in the fore- and hindlimbs of the guinea pig. Rotation relative to the lateral axis].

Influence of adequate vestibular stimulation by tilting about a transverse axis on the locomotor activity of fore- and hindlimb muscles was investigated in precollicularly decerebrated guinea pigs. The locomotor activity was evoked by electrical stimulation of the mesencephalic locomotor region. An increase in the forelimb extensors activity and a decrease in the hindlimb extensors activity in the support phase of the locomotor cycle were observed during head downward position, opposite changes of these activities were observed during head upward position. A decrease in the forelimb flexor activity in swing phase during head downward position and an increase in this activity during head upward position was registered. Phase shifts of the locomotor activity changes of forelimb extensors altered from 60 to -30 degrees, hindlimb extensors--from -150 to -220 degrees, forelimb flexors--from -140 to -220 degrees during sinusoidal tilting in frequency range of 0.02-0.4 Hz and amplitude +/- 20 degrees. Mechanisms of observed changes in the locomotor activity of muscles are discussed.

Animals↗