Caudate nucleus lesion selectively increases paradoxical sleep episodes in the rat.

The EMG, ECG and the behavioral activity of seven rats were recorded for three days previous to and 24 hours after lesioning both caudate-putamen complexes. Following the lesion, the paradoxical sleep stage lengthened by about 248%, without noticeable changes in the slow wave sleep or in the waking stages. The greatest increase was obtained with lesions placed in the mediomedial portion of the caudate-putamen complex. In other six rats submitted to the above procedure except that the lesions were placed in the anterior cerebral cortex, and also in five more rats implanted in both caudate-putamen complexes but not lesioned, no change was noted in the waking, paradoxical sleep or slow wave sleep stages.