Involvement of the human pedunculopontine nucleus region in voluntary movements.

Division of Brain Imaging & Behaviour Systems-Neuroscience, Toronto Western Hospital, McLaughlin Pavilion, Toronto, Ontario M5T 2S8, Canada.
Neurology (Impact Factor: 8.3). 09/2010; 75(11):950-9. DOI: 10.1212/WNL.0b013e3181f25b35
Source: PubMed

ABSTRACT The pedunculopontine nucleus region (PPNR) is being investigated as a target for deep brain stimulation (DBS) in Parkinson disease (PD), particularly for gait and postural impairment. A greater understanding of how PPNR activities and oscillations are modulated with voluntary movements is crucial to the development of neuromodulation strategies.
We studied 7 patients with PD who underwent DBS electrode implantations in the PPNR. PPNR local field potential and EEG were recorded while patients performed self-paced wrist and ankle movements.
Back-averaging of the PPNR recording showed movement-related potentials before electromyography onset. Frequency analysis showed 2 discrete movement-related frequency bands in the theta (6- to 10-Hz) and beta (14- to 30-Hz) ranges. The PPNR theta band showed greater event-related desynchronization with movements in the ON than in the OFF medication state and was coupled with the sensorimotor cortices in the ON state only. Beta event-related desynchronization was observed in the PPNR during the premovement and movement execution phases in the OFF state. In contrast, premovement PPNR beta event-related synchronization occurred in the ON state. Moreover, beta band coherence between the PPNR and the midline prefrontal region was observed during movement preparation in the ON but not the OFF state.
Activities of PPNR change during movement preparation and execution in patients with PD. Dopaminergic medications modulate PPNR activities and promote the interactions between the cortex and PPNR. Beta oscillations may have different functions in the basal ganglia and PPNR, and may be prokinetic rather than antikinetic in the PPNR.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The rapid release of prepared movements by a loud acoustic stimulus capable of eliciting a startle response has been termed the StartReact effect (Valls-Solé et al., 1999), and premotor reaction times (PMTs) of <70 ms are often observed. Two explanations have been given for these short latency responses. The subcortical storage and triggering hypothesis suggests movements that can be prepared in advance of a “go” signal are stored and triggered from subcortical areas by a startling acoustic stimulus (SAS) without cortical involvement. Alternatively, it has been hypothesized that the SAS can trigger movements from cortical areas through a faster pathway ascending from subcortical structures. Two experiments were designed to examine the possible role of primary motor cortex in the StartReact effect. In Experiment 1, we used suprathreshold transcranial magnetic stimulation (TMS) during the reaction time (RT) interval to induce a cortical silent period in the contralateral primary motor cortex (M1). Thirteen participants performed 20° wrist extension movements as fast as possible in response to either a control stimulus (82dB) or SAS (124 dB). PMTs for startle trials were faster than control trials, while TMS significantly delayed movement onset compared to No TMS or Sham TMS conditions. In Experiment 2, we examined the StartReact effect in a highly cortically represented action involving speech of a consonant-vowel (CV) syllable. Similar to previous work examining limb movements, a robust StartReact effect was found. Collectively, these experiments provide evidence for cortical (M1) involvement in the StartReact effect.
    Neuroscience 03/2014; · 3.33 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This brief review resolves a number of persistent conflicts regarding the location and characteristics of the mesencephalic locomotor region, which has in the past been described as not locomotion-specific and is more likely the pedunculopontine nucleus (PPN). The parameters of stimulation used to elicit changes in posture and locomotion we now know are ideally suited to match the intrinsic membrane properties of PPN neurons. The physiology of these cells is important not only because it is a major element of the reticular activating system, but also because it is a novel target for the treatment of gait and postural deficits in Parkinson's disease (PD). The discussion explains many of the effects reported following deep brain stimulation (DBS) of the PPN by different groups and provides guidelines for the determination of long-term assessment and effects of PPN DBS. A greater understanding of the physiology of the target nuclei within the brainstem and basal ganglia, amassed over the past decades, has enabled increasingly better patient outcomes from DBS for movement disorders. Despite these improvements, there remains a great opportunity for further understanding of the mechanisms through which DBS has its effects and for further development of appropriate technology to effect these treatments. We review the scientific basis for one of the newest targets, the PPN, in the treatment of PD and other movement disorders, and address the needs for further investigation.
    Journal of Neural Transmission 06/2014; · 2.87 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Background: Deep brain stimulation (DBS) for the treatment of movement disorders has provided researchers with an opportunity to record electrical oscillatory activity from electrodes implanted in deep brain structures. Extracellular activity recorded from a population of neurons, termed local field potentials (LFPs), has shed light on the pathophysiology of movement disorders and holds the potential to lead to refinement in existing treatments. Objective: This paper reviews the clinical significance of LFPs recorded from macroelectrodes implanted in basal ganglia and thalamic targets for the treatment of Parkinson's disease, essential tremor and dystonia. Methods: Neural population dynamics and subthreshold events, which are undetectable by single-unit recordings, can be examined with frequency band analysis of LFPs (frequency range: 1-250 Hz). Results: Of clinical relevance, reliable correlations between motor symptoms and components of the LFP power spectrum suggest that LFPs may serve as a biomarker for movement disorders. In particular, Parkinson's rigidity has been shown to correlate with the power of beta oscillations (13-30 Hz), and essential tremor coheres with oscillations of 8-27 Hz. Furthermore, evidence indicates that the optimal contacts for DBS programming can be predicted from the anatomic location of beta and gamma bands (48-200 Hz). Conclusion: LFP analysis has implications for improved electrode targeting and the development of a real-time, individualized, 'closed-loop' stimulation system. © 2014 S. Karger AG, Basel.
    Stereotactic and Functional Neurosurgery 08/2014; 92(4):251-263. · 1.46 Impact Factor

Full-text (2 Sources)

Available from
May 28, 2014