MULTI-NEURONAL SIGNALS FROM THE RETINA - ACQUISITION AND ANALYSIS

Throughout the central nervous system, information about the outside w orld is represented collectively by large groups of cells, often arran ged in a series of 2-dimensional maps connected by tracts with many fi bers. To understand how such a circuit encodes and processes informati on, one must simultaneously observe the signals carried by many of its cells. This article describes a new method for monitoring the simulta neous electrical activity of many neurons in a functioning piece of re tina. Extracellular action potentials are recorded with a planar array of 61 microelectrodes, which provides a natural match to the flat mos aic of retinal ganglion cells. The voltage signals are processed in re al time to extract the spike trains from up to 100 neurons. We also pr esent a method of visual stimulation and data analysis that allows a r apid characterization of each neuron's visual response properties. A r andomly flickering display is used to elicit spike trains from the gan glion cell population. Analysis of the correlations between each spike train and the flicker stimulus results in a simple description of eac h ganglion cell's functional properties. The combination of these tool s will allow detailed study of how the population of optic nerve fiber s encodes a visual scene.