Functional Parcellation of the Lateral Mesencephalus

Abstract

The mesencephalic locomotor region (MLR), which includes the pedunculopontine nucleus (PPN) and the cuneiform nucleus (CN), has been recently identified as a key structure for locomotion and gait control in mammals. However, the function and the precise anatomy of the MLR remain unclear in humans. To study the lateral mesencephalus, we used fMRI in 15 right-handed healthy volunteers performing two tasks: imagine walking in a hallway and imagine an object moving along the same hallway. Both tasks were performed at two different speeds: normal and 30% faster. We identified two distinct networks of cortical activation: one involving motor/premotor cortices and the cerebellum for the walking task and the other involving posterior parietal and dorsolateral prefrontal cortices for the object moving task. In the lateral mesencephalus, we found that two different but anatomically connected parts of the MLR were activated during the fast condition of each task. The CN and the dorsal part of the PPN were activated during the fast imaginary walking task, whereas the ventral part of the PPN and the ventral part of the reticular formation were activated while subjects were imagining the object moving fast. Our data suggest that the lateral mesencephalus participates in different aspects of gait in humans, with the CN and dorsal PPN controlling motor aspects of locomotion and the ventral PPN being involved in integrating sensory information.

Neural substrates of levodopa‐responsive gait disorders and freezing in advanced Parkinson's disease: A kinesthetic imagery approach

“…EMG recordings confirmed that the motor activations seen during MI did not result from actual movements. Such motor activations during gait imagery have already been reported [Karachi et al, ; Malouin et al, ; Miyai et al, ; Sacco et al, ; van der Meulen et al, ], and could thus be specifically related to the use of kinesthetic MI.…”

“…Because of a priori hypotheses regarding the involvement of cortical (mainly in frontal, premotor, and motor areas), subcortical (thalamus and BG), and brainstem regions, an uncorrected threshold (P < 0.001) for multiple comparisons across the whole brain (Z-scores > 3.10) was applied at the voxel level using flexible factorial design with the linear contrasts defined above. This level of significance has been used in previous neuroimaging studies having used MI method with a similar, or higher, number of subjects [e.g., Guillot et al, 2009;Jahn et al, 2004;Karachi et al, 2010Karachi et al, , 2012Malouin et al, 2003;Samuel et al, 2001;Thobois et al, 2000Thobois et al, , 2002van der Meulen et al, 2014]. Only voxels exceeding a threshold of a P-value < 0.001 uncorrected and clusters of a minimum of 20 contiguous voxels were considered significant.…”

“…In recent years, MI has been increasingly used to investigate the neural control of normal and parkinsonian gait Bakker et al, 2008;Cr emers et al, 2011Cr emers et al, , 2012Karachi et al, 2010Karachi et al, , 2012 Malouin et al, 2003;Peterson et al, 2014a,b;Snijders et al, 2011;Wai et al, 2012; see review by Maillet et al, 2012a]. Overall, these studies have confirmed the involvement of frontoparietal areas, basal ganglia (BG), cerebellum, and brainstem during MI of natural gait in controls.…”

Resting‐state functional connectivity of subcortical locomotor centers explains variance in walking capacity

“…(Allali et al, 2014, Bakker et al, 2008, Cremers et al, 2012, Godde and Voelcker-Rehage, 2010, Iseki et al, 2008, Hanakawa et al, 1999, Jaeger et al, 2014, Jaeger et al, 2016, Jahn et al, 2008, Jahn et al, 2004, Karachi et al, 2012, la Fougere et al, 2010, Martinez et al, 2016, van der Meulen et al, 2014, Wagner et al, 2008, Wutte et al, 2012, Zwergal et al, 2012) The ALE significance map (p<0.01, uncorrected) included 6,790 voxels (54,320 mm 3 ) distributed across the brain with the largest clusters in the anterior, superior, medial cerebellum, medial motor cortices, and bilateral anterior insular cortices (Supplemental Figure 1). Eighty-one out of 296 parcels (27%) from the BnS atlas had ≥15 voxels (120 mm 3 ) with gait-related ALE p<0.01.…”

Continuous stimulation of the pedunculopontine tegmental nucleus at 40Hz affects preparative and executive control in a delayed sensorimotor task and reduces rotational movements induced by apomorphine in the 6-OHDA parkinsonian rat

“…However, besides affecting motor performance, PPTg-DBS has remarkable consequences on non-motor functions, in particular in regulating REM sleep and arousal mechanisms [2][3][4]6,27].…”