How does dark adaptation change centre-surround inhibition in retinal receptive fields?

During dark adaptation, the physiological organization of retinal receptive fields undergoes a significant change regarding centre-surround inhibition. In a light-adapted state, these fields exhibit a concentric structure where the central region and the surrounding annular ring exert mutual inhibition, which helps the retina detect local contrast and maintain sensitivity control.12

As the eye undergoes dark adaptation, the surrounding area of opposite activity becomes ineffective. This reduction in inhibitory interaction between the centre and the periphery causes the receptive field to effectively shrink in terms of its inhibitory influence. Consequently, this removal of inhibition allows for greater functional convergence, meaning the regions over which the retina can summate signals actually increase. This process is a key factor in the increased sensitivity of the eye in low-light conditions, as it allows the retina to collect impulses over a larger area, effectively lowering the threshold for detecting light.13