Spatialtemporal Correlated Firing Patterns Of Gnaglion Cells In Frog Retina

The retina is the first stage for visual information processing. Photoreceptors transmit the light stimulus into electrical signals which are further processed by retinal circuits. Retinal ganglion cells send all the visual information to the brain via spikes transmitted through their axons. Generally, visual scenes to be processed by retina are complicated, and the retina is constrained by the anatomic bottleneck structure of visual pathway, the noise within neuronal circuits and so on. Spatial-temporal coding pattern is considered as an efficient way of information processing under such constraint. In the present study, spatial-temporal encoding properties was investigated based on bullfrog retinal ganglion cells activities recorded via multi-electrode array system in response to particular visual stimulus.The main results include two parts:(1) Temporal correlation indices of neurons were estimated based on information theory; neurons'spatial correlation indices were also calculated. Data analysis revealed that, for each single neuron, temporal and spatial correlation indices were associated with each other: larger temporal correlation index was linked to bigger spatial correlation index. Further more, burst activities (inter-spike intervals < 6 ms) played an important role in retinal spatial-temporal firing patterns: a neuron firing more burst spikes usually corresponded to bigger temporal and spatial correlation indices, which reflected strong temporal and spatial correlations. Model analysis suggested that spatial-temporal correlations were helpful for predicting neurons'spiking time precisely. (2) Spatial correlation based on different kinds of spike activities was analyzed. Each single spike train was split into two distinct subsequences: burst-like spikes (inter-spike interval≤30 ms), solitary spikes (inter-spike interval > 30 ms); It's found that burst-like activities shared stronger spatial correlation as compared to that of solitary spikes; in addition, correlated burst-like spikes represent smaller receptive field than that of solitary spikes, indicating capability of encoding detailed visual information.In short, spatial-temporal firing pattern contributes to retinal visual information processing, and burst activities contribute significantly in modulating the spatial-temporal firing pattern.