The pedunculopontine tegmental nucleus—A functional hypothesis from the comparative literature

Abstract

We present data from animal studies showing that the pedunculopontine tegmental nucleus—conserved through evolution, compartmentalized, and with a complex pattern of inputs and outputs—has functions that involve formation and updates of action–outcome associations, attention, and rapid decision making. This is in contrast to previous hypotheses about pedunculopontine function, which has served as a basis for clinical interest in the pedunculopontine in movement disorders. Current animal literature points to it being neither a specifically motor structure nor a master switch for sleep regulation. The pedunculopontine is connected to basal ganglia circuitry but also has primary sensory input across modalities and descending connections to pontomedullary, cerebellar, and spinal motor and autonomic control systems. Functional and anatomical studies in animals suggest strongly that, in addition to the pedunculopontine being an input and output station for the basal ganglia and key regulator of thalamic (and consequently cortical) activity, an additional major function is participation in the generation of actions on the basis of a first‐pass analysis of incoming sensory data. Such a function—rapid decision making—has very high adaptive value for any vertebrate. We argue that in developing clinical strategies for treating basal ganglia disorders, it is necessary to take an account of the normal functions of the pedunculopontine. We believe that it is possible to use our hypothesis to explain why pedunculopontine deep brain stimulation used clinically has had variable outcomes in the treatment of parkinsonism motor symptoms and effects on cognitive processing. © 2016 International Parkinson and Movement Disorder Society

Reward and Behavioral Factors Contributing to the Tonic Activity of Monkey Pedunculopontine Tegmental Nucleus Neurons during Saccade Tasks

“…Additionally, after several recording sessions when monkey 1 began to perform the normal and visible tasks similarly, the proportion of the sustained-type neurons was less (Figure 8B). These observations suggest that this type of PPTg neuron contributes to the execution of conditioned task behavior, which is consistent with a similar view of Gut and Winn (2016). Classically, the PPTg was regarded as a locomotor center (Garcia-Rill and Skinner, 1988) because stimulation of the PPTg area induced locomotion (Garcia-Rill et al, 1987).…”

“…PD patients with freezing of gate also exhibit disturbances in upper limb movement (Nieuwboer et al, 2009), voluntary saccades (Walton et al, 2015), and speech (Park et al, 2014). The findings of a recent study suggested roles of the PPTg in the initial analysis of sensory data and in rapid decision making (Gut and Winn, 2016). Moreover, PD patients with freezing of gate showed no pre-cue effect, whereas healthy controls exhibited faster reaction times in response to loud auditory stimuli (Thevathasan et al, 2011).…”

Lesions causing freezing of gait localize to a cerebellar functional network

“…20–22 One of these regions, termed the cerebellar locomotor region (CLR), lies at the midline of the cerebellar white matter. Stimulation of this region can induce locomotion in experimental animals.…”

Circuits Regulating Pleasure and Happiness: The Evolution of the Amygdalar-Hippocampal-Habenular Connectivity in Vertebrates

“…Ocaña et al (2015) have recently obtained evidence for functional connectivity between the dorsal and dorsomedial part of lateral pallium and certain brainstem motor centers (pretectum, tectum, midbrain tegmentum and locomotor region, and reticulospinal cells) in lampreys. The brainstem structures they described may correspond to brainstem structures for smooth pursuit eye movements (Mustari et al, 2009) and the pedunculopontine nucleus (PPN, Benarroch, 2013; Gut and Winn, 2016). Both structures are connected with the cerebral neocortex in primates (Matsumura et al, 2000; Aravamuthan et al, 2007, 2009; Mustari et al, 2009).…”