Different functions of rat's pedunculopontine tegmental nucleus are reflected in cortical EEG

Previous investigations suggest a crucial role of the pedunculopontine tegmental nucleus (PPTg) in elicitation of cortical EEG alterations during paradoxical sleep. In order to reveal a participation of this nucleus in the regulation of the cortical EEG also during waking states and slow wave sleep unilateral ibotenic acid lesions of this nucleus were made in 12 Long-Evans rats. The lesion induced alterations of the frontal and occipital EEG were determined by FFT spectral power analysis. The lesion caused ipsilaterally a suppression of the hippocampal theta rhythm recorded on the occipital cortex during exploratory sniffing. During head washing the frontal delta waves were found to be elevated ipsilaterally. Suppressions of the slow sleep waves were found in the contralateral occipital as well as in the frontal EEG. The results indicate involvements of the PPTg in the regulation of the hippocampal and of the motor activity in waking states as well as in the regulation of the sleep delta waves.