Adaptive Coding in Retinal Ganglion Cells

Sensory systems show many aspects of adaptation. The chicken retinal ganglion cells examined in our study showed typical light adaptation and contrast adaptation. The prolonged presence of contrast or luminance stimuli reduced the firing rate of retinal ganglion cells during the adaptation phase. However, further experimental results suggest that the information about stimulation might be stored in the retinal neural network in spite of the reduction in firing rate during the adaptation process. We found that the application of background light may result in some modification for retina sensitivity, in an illumination level dependent manner. This may indicate a novel adaptive mechanism underlying the phenomena of that contrast discrimination improved when the background illumination was increased. Inspired by the physiological mechanisms, a simple and biophysically realistic model was then employed, where the spiking neuron could change their membrane properties, especially the ion channel activity, during the process of adaptation or synaptic modification. Our analyses reveal that activity-dependent regulation of membrane properties contributes to sensitivity adaptation, which may be potentially useful for neural signal detection and information processing