Morphine catalepsy as an adaptive reflex state in rats.

@article{Ryck1984MorphineCA,
  title={Morphine catalepsy as an adaptive reflex state in rats.},
  author={Marc De Ryck and Philip Teitelbaum},
  journal={Behavioral neuroscience},
  year={1984},
  volume={98 2},
  pages={243-61}
}
These experiments demonstrate that morphine-induced catalepsy consists of two complementary, but opposite, behavioral extremes (rigid immobility and sudden locomotor bursts), each of which can be controlled by distinct classes of external stimuli. When stimuli that involve pain and/or nonnociceptive skin pressure are tonic (continuous), morphine-induced electroencephalographic (EEG) deactivation and behavioral immobility are potentiated, even to the extent that a stimulation-bound reversible… CONTINUE READING