Habituation of distraction to a tone in the absence of neocortex in rats.

Normal rats and rats with in excess of 95% of neocortex surgically removed (decorticated) were trained to push a food tray door on a Fixed Ratio schedule. Once the behaviour was established a 3720 Hz, 70 dB tone was presented 4 times per session and the duration of distraction from the operant baseline was recorded. Both groups of rats habituated to the presence of the tone within a single session and the effects were retained over a 24 h interval. The decorticates, but not the normal animals, showed a partial spontaneous recovery of the habituated response between sessions. It was concluded that neocortex is not required for either short-term or long-term habituation in this situation though long-term habituation is more complete when neocortex is present.