Figure 8.

Delayed acquisition of CS− implies safety learning. A, An additional phase was performed where the CS− was now reinforced. Shown is a direct comparison between acquired CRs (blinks) during the acquisition phase for the CS+ (solid line), and during the reversal phase for the CS−, dashed line. Learning was delayed and reduced, implying the CS− acquired safety value. B, Raster plots overlaid with PSTHs for two different neurons (rows) that signal safety during late acquisition (left column, response to the CS−), but stop responding when this cue becomes a CS+ during reversal (right column).