Temporal aspects of neural coding in the retina and lateral geniculate.

The early stages of visual processing provide excellent models for the study of how information is represented in, and processed by, the activity of neurons. The fact that the retina contains both non-spiking and spiking neurons leads us to frame questions about neural coding in a general fashion, rather than in a manner specific either to point processes or continuous signals. In particular, we ask about the role of the statistical structure of the response, the extent to which the neural representation is 'literal', and how information content can be estimated from laboratory data. The broad theme that emerges from a review of experimental data is that each stage of visual processing is accompanied by new features, including adaptive filtering, feedback, rectification and spike generation. These dynamical elements allow an increasingly rich set of strategies for the representation and processing of visual information at retinal and thalamic levels.