GABAergic regulation of spontaneous spike patterns in the developing rabbit retina

• Retinal wave dynamics undergoes a profound transition from stage II to stage III.
• The waves become smaller and more localized in spatial domain after the transition.
• The wave pattern becomes more diverse in temporal domain after the transition.
• GABAA receptor-mediated inhibition plays an important role in these changes.

Spontaneous retinal waves play a critical role in the establishment of precise neuronal connections in the developing visual system. Retinal waves in mammals progress through three distinct developmental stages prior to eye opening. Using multielectrode array (MEA) recording from the rabbit retina, this study found characteristic changes in the spontaneous spike pattern in the ganglion cell layer during the transition from stage II to stage III retinal waves. These changes led to an increased diversity in the spatiotemporal pattern of the spontaneous activity, consistent with a potential role of stage III retinal waves in the establishment of diverse, cell type-specific neuronal connectivity during visual system development. The study also showed that GABAergic inhibition, predominantly mediated by GABAA receptors, was critical in breaking down large waves of ganglion cell spiking into spatially restricted and temporally diverse spike patterns at stage III, suggesting an important role of amacrine cells in shaping the diverse spontaneous activity patterns of developing ganglion cells.