Abstract
Abstract: :
Purpose:The retinal synaptic network continues its development after birth. This postnatal development is experience-dependent and might have a critical period during which the retina shows evidence of plasticity. We studied the developmental changes of the ERG in cyclic light-reared mice as well as the effect of light deprivation on ERG's oscillatory potentials (OP) and its reversibility. Methods:Two groups of wild type C57BL/6 mice were born and reared in darkness until 30 and 60 days respectively. A third group of mice were dark-reared from birth to P60 and then were transferred to cyclic lighting conditions for 10 days. All groups had controls of age-matched mice reared in cyclic light conditions. Cyclic light-reared mice were dark adapted for at least 30 min before ERG recording. Results:In cyclic light-reared mice, the amplitudes of a-wave, b-wave and the OPs decrease after P30. The amplitude of the a-wave, b-wave and the OPs at P70 are respectively 61.9%, 70.2% and 43.4% of their values at P30. Dark rearing suppressed the OPs to 68% of their control values at P30 (P= .01). With prolonged dark rearing to P60, OPs were 61.6% of their control and the difference continues to be significant(p= .001). This suppression recovers completely when the mature 60 days old mice are exposed to cyclic-light exposure for 10 days. Conclusion:ERG components, reflecting the activity of subsets of retinal cells, continue their maturation after birth. The a-wave, b-wave and OPs amplitudes decrease gradually after P30. Light-deprivation causes decrease of the oscillatory potentials, which are thought to reflect the inner retinal function. This effect is present as long as animals are kept in dark. The fact that this change is reversed by light exposure even in the mature P60 mice suggests the persistence of activity-dependent plasticity in inner retinal synapses.
Keywords: 520 plasticity • 564 retinal development • 396 electroretinography: non-clinical