Influence of spontaneous activity and visual experience on developing retinal receptive fields

Area of Science:

• Neuroscience
• Developmental Biology
• Retinal Physiology

Background:

• The influence of early neural activity on retinal function remains unclear.
• Developing vertebrate retinas exhibit spontaneous ganglion cell bursts before visual experience.
• These bursts typically cease around birth or eye-opening.

Purpose of the Study:

• To investigate the impact of early spontaneous bursting and visual experience on receptive field development in turtle retinal ganglion cells.
• To determine if spontaneous neural activity is essential for receptive field expansion.

Main Methods:

• Monitored spontaneous bursting and receptive field size in developing turtles under normal and dark-reared conditions.
• Utilized curare, a nicotinic cholinergic antagonist, delivered via slow-release polymer implants to chronically block acetylcholine-dependent spontaneous bursting.
• Assessed receptive field development in hatchlings with blocked spontaneous activity.

Main Results:

• Dark-reared turtles showed persistent spontaneous bursting and over twice the normal receptive field expansion.
• Chronic curare treatment abolished dark-induced receptive field expansion.
• In normal light/dark cycles, curare treatment resulted in smaller receptive fields than normal.

Conclusions:

• Early, acetylcholine-dependent spontaneous bursts are critical regulators of receptive-field outgrowth in retinal ganglion cells.
• Visual experience onset triggers the cessation of spontaneous bursts, stabilizing receptive fields to mature sizes.
• Spontaneous neural activity plays a key role in shaping visual system development.