Contrast Adaptation is in Part an Intrinsic Membrane Property
A. Presentation of a 20-60-20% contrast adaptation protocol results in a typical decrease in neuronal response during the adaptation that persists following return to the lower contrast stimulus. B. Replacement of the high contrast stimulus with the intracellular injection of a 2 Hz sine wave stimulus also results in adaptation and a remarkable decrease in the response to the visual stimulus. C. Similarly, presentation of the high contrast stimulus results in a decrease in the response to the intracellular injection of a low amplitude 2 Hz sinewave.
This result indicates that adaptation to a visual stimulus can be induced merely through the intracellular injection of current and the generation of action potentials. Likewise, adaptation to a visual stimulus reduces the response to intracellular current injection. Therefore a major component of adaptation is mediated by intrinsic membrane properties and not synaptic or presynaptic networks.