THE PEDUNCULOPONTINE TEGMENTAL NUCLEUS - A ROLE IN COGNITIVE-PROCESSES

The cholinergic pedunculopontine tegmental nucleus, located in the bra instem and part of the reticular formation, has been traditionally lin ked to motor function: arousal and sleep. Its anatomical connections, however, raise the possibility that the pedunculopontine tegmental nuc leus is also involved in other aspects of behaviour such as motivation , attention and mnemonic processes. This is of obvious importance, sin ce the pedunculopontine tegmental nucleus undergoes degeneration in hu man neurodegenerative disorders also characterized by attentional and/ or mnemonic deficits. Moreover, recent behavioural animal work suggest s that cognitive processes may be represented in the pedunculopontine tegmental nucleus. The difficulty that faces research in this area, ho wever, is the possible influence of cognition by other processes, such as arousal state, motivation and motor function. Nevertheless, by rev iewing the literature, the pedunculopontine tegmental nucleus seems to be involved in attentional and possibly also in learning processes. T hese processes could be mediated by influencing cortical fuction via t he thalamus, basal forebrain and basal ganglia. The involvement of the pedunculopontine tegmental nucleus in mechanisms of memory, however, seems to be rather unlikely.