Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ADAPTATION, OCULAR”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 775 records · Page 43Linked to original sources
PubMed1989

Behavior of floccular Purkinje cells correlated with adaptation of vestibulo-ocular reflex in pigmented rabbits.

The responsiveness of floccular Purkinje cells to head oscillations was examined in alert pigmented rabbits subjected to adaptation of horizontal vestibulo-ocular reflex (HVOR) under three different combinations of turntable and screen oscillations. Purkinje cells involved in the HVOR control (H-zone cells) were identified by local stimulation effects that induced horizontal eye movements. In control states, simple spike discharges of H-zone cells were modulated predominantly out of phase with the velocity of sinusoidal turntable oscillation (0.1Hz, 5 degrees peak-to-peak). A sustained 180 degrees outphase combination (5 degrees turntable and 5 degrees screen oscillation) was found to increase the average HVOR gain by 0.16, at which point the majority of H-zone cells increased the outphase simple spike modulation. A sustained inphase combination (5 degrees turntable and 5 degrees screen oscillation) decreased the average HVOR gain by 0.09, with the majority of H-zone cells decreasing the outphase simple spike modulation or becoming converted to the inphase modulation. With a vision-reversal combination (5 degrees turntable and 10 degrees screen oscillation), there was no change in the gain of the HVOR, but a moderate advancement in the phase. In this case, H-zone cells showed no appreciable changes in their simple spike modulation. Complex spike discharges of all H-zone cells tested were modulated in response to optokinetic stimuli involved in the combinations of turntable and screen oscillations. These results support the hypothesis that H-zone cells adaptively control HVOR dynamic characteristics through modification of mossy fiber responsiveness to head oscillation under influences of retinal error signals conveyed by climbing fiber afferents.

Action Potentials↗
PubMed1990

[Ocular prosthesis production in Norway].

Individually adapted acrylic ocular prostheses are presented as an alternative to glass prostheses, which up to now have been the technique available to Norwegian patients who have lost an eye. The article describes the technique used to produce acrylic eyes and sums up the advantages of acrylic eyes compared with prostheses of glass.

Acrylic Resins↗
PubMed2005

The role of gravity in adaptation of the vertical angular vestibulo-ocular reflex.

The gain of the vertical angular vestibulo-ocular reflex (aVOR) was adapted in side-down and prone positions in two monkeys and tested in four planes: left-/right-side down; forward/backward; and two intermediate planes that lie approximately in the planes of the vertical semicircular canal pairs, left anterior/right posterior (LA/RP) and right anterior/left posterior (RA/LP). Gain changes, expressed as a percent of preadapted values, were plotted as a function of head orientation in the planes of tilt, and fitted with sinusoids to obtain the gravity-dependent (amplitude) and gravity-independent (bias) components of adaptation. Gravity-dependent gain changes were always maximal when tested in a plane that included the head orientation in which the aVOR gain had been adapted. Changes were minimal when the head was tilted in a plane orthogonal to the plane of adaptation, and were smaller but still significant when tested in the two intermediate planes. Gravity-independent VOR gain changes were uniform over all planes of head tilt. Thus, the gravity-dependent and gravity-independent components could be separated experimentally. The aVOR gain changes from the head tilts in different directions were utilized to reconstruct the gain changes in three dimensions. They formed a continuous surface, which peaked in and around the position of adaptation. These studies support the postulate that gain adaptation has both gravity-independent and gravity-dependent components, and further show that these gain changes have a three-dimensional structure. These results are similar to those in humans, indicating that the gravity-dependent adaptation of the aVOR is likely to be a common phenomenon across species.

Acclimatization↗
PubMed1992

Factors influencing accommodative adaptation.

Previous studies have ascertained that a broad range of parameters have the facility to induce or modify accommodative adaptation, i.e., the post-task shift in dark accommodation (DA) which may be observed after a period of sustained fixation. This paper reviews the optical (i.e., related to a change in the form of the retinal image) and nonoptical (i.e., independent of the composition of the retinal image) stimuli which can influence the degree of adaptation. It is concluded that DA probably represents an aggregate response resulting from multiple inputs whose interactions may be too complex to allow the isolation and measurement of any single nonoptical component. Accordingly, the exact mechanism of accommodative adaptation remains unclear at the present time.

Accommodation, Ocular↗
PubMed1985

Adaptation of saccadic and vestibulo-ocular systems after extraocular muscle tenectomy.

Adaptation of saccadic magnitude and vestibulo-ocular reflex gain (VOR) was examined in six monkeys that had undergone a tenectomy of the medial and lateral recti of one eye. After the tenectomy, when the normal eye was patched, a conjugate increase in saccadic magnitude and VOR was observed in both eyes. Subsequent unpatching resulted in selective (nonconjugate) changes in the two eyes such that control values of saccadic magnitude and VOR gain were eventually reestablished in both eyes. Evidence that this return to normal was mediated by a selective adaptation of the neural innervation to one eye was provided by the following observations: (1) saccades in the normal eye were of a lower peak velocity and longer duration after normalization than prior to the tenectomy; and (2) repatching the tenectomized eye after normalization produced a selective return of deficits in that eye over a period of a few days. Thus, the saccadic and vestibulo-ocular systems can be adapted in both a conjugate and a selective or nonconjugate fashion.

Animals↗