Pedunculopontine nucleus

The pedunculopontine nucleus (PPN) (or pedunculopontine tegmental nucleus, PPTN or PPTg) is located in the brainstem, caudal to the substantia nigra and adjacent to the superior cerebellar peduncle. It has two divisions, one containing cholinergic neurons, the pars compacta, and one containing mostly glutamatergic neurons, the pars dissipata. The PPN is one of the main components of the reticular activating system. It was first described in 1909 by Louis Jacobsohn-Lask, a neuroanatomist born in Bydgoszcz.