Nucleus Tegmental Pedunculopotine
One loci of the amenta inhibiting, enhancing or imitating the action of the neurotransmitter acetycholine is the pedunculopontine tegmental nucleus located in the brainstem and part of the reticular formation. It has been traditionally linked to motor function, arousal and sleep. The nucleus tegmental pedunculopontine may participate in attentional and learning processes mediated by influencing cortical function via the thalamus, basal forebrain and basal ganglia. The involvement of the pedunculopontine tegmental nucleus in mechanisms of memory seems unlikely. *1
Further, the pedunculopontine tegmental nucleus shares a structure analogous to substantia nigra which contains two main compartments: the pars compacta and the pars reticulata. The former contains dopamine neurons that project widely within the basal ganglia while the latter is in receipt of corticostriatal output. Similarly, the PPTg contains the Ch5 acetylcholine containing neurons that project to the thalamus and corticostriatal systems (notably the pars compacta of substantia nigra and the subthalamic nucleus) while the non-cholinergic neurons of the pedunculopontine are in receipt of corticostriatal output. Assessment of the location, composition and connections of the pedunculopontine tegmental nucleus is made to support the hypothesis that it has structural similarities with substantia nigra. Assessment of the motor, sensory and cognitive functions of the pedunculopontine is also made, suggesting functional similarities exist also. Having a clear model of pedunculopontine structure and function is a matter of some importance. It is clearly involved in Parkinson's disease and could potentially be a target for therapeutic intervention.*2
Further studies indicate that bilateral lesions of the tegmental pedunculopontine nucleus double dissociate the rewarding and aversive motivational effects of nicotine. *3
These findings suggest that the nucleus tegmental pedunculopontine is responsible for attention, learning, rewarding and has a symbiotic, functional relationship with other amenta loci specifically the substantia nigra as it relates to cognition.
*1 The pedunculopontine tegmental nucleus: a role in cognitive processes? Sleekier, Thomas; Inglis, Wendy; Winn, Philip; Sahgal, Arjun. Brain Research Reviews, Volume 19, Issue 3; August 1994, pages 298-318.
*2 How best to consider the structure and function of the pedunculopontine tegmental nucleus: Evidence from animal studies. Winn, Philip. Journal of Neurological Sciences. Volume 248, Issues 1-2, October 2006, Pages 234-250
*3 Lesions of the Tegmental Pedunculopontine Nucleus Block the Rewarding Effects and Reveal the Aversive Effects of Nicotine in the Ventral Tegmental Area. Laviolette, Steven; Alexson, Tania; van der Kooy, Derek. Journal of Neuroscience. Volume 11, Issue 19, October 2022, Pages 8653-8660.