Figure 6.
Visual information encoded by the state of the cell. A, The state information Istate is that visual information that can only be decoded by identifying which of the visually triggered responses were bursts (see Materials and Methods). Each symbol shows Istate in units of bits per second for the responses of one cell to the white-noise stimulus (x-axis) versus the natural stimulus (y-axis). The symbol size is proportional to the burst rate of the cell, averaged across the two stimulus conditions. Dotted lines indicate x = 0, y = 0, and x = y. Information rate estimates were empirically corrected for finite data size (see Materials and Methods). Filled symbols indicate cells for which this correction was small and linear under both stimulus conditions. Open symbols indicate cells that did not pass this criterion. Results shown are for spike trains binned at 2 ms resolution and words of length 8 bins; extrapolating to infinite word length gave qualitatively similar results. B, The state information expressed in bits per burst (Istate in bits per second divided by burst rate in bursts per second) compared with the trigger information expressed in bits per response (Itrigger in bits per second divided by response rate in responses per second, in which a response is either a single spike or an entire burst). Each symbol represents the response of a single cell to either the natural stimulus (○) or the white-noise stimulus (Δ). The symbol size is proportional to the burst rate of the cell for that stimulus. Filled and open symbols defined as in A. Calculation parameters as in A.