Somatosensory evoked potentials recorded from the human pedunculopontine nucleus region

Abstract

The pedunculopontine nucleus region (PPNR) is an integral component of the midbrain locomotor region and has widespread connections with the cortex, thalamus, brain stem, cerebellum, spinal cord, and especially, the basal ganglia. No previous study examined the somatosensory connection of the PPNR in human. We recorded somatosensory evoked potentials (SEP) from median nerve stimulation through deep brain stimulation (DBS) electrodes implanted in the PPNR in 8 patients (6 with Parkinson's disease, 2 with progressive supranuclear palsy). Monopolar recordings from the PPNR contacts showed triphasic or biphasic potentials. The latency of the largest negative peak was between 16.8 and 18.7 milliseconds. Bipolar derivation revealed phase reversal with median nerve stimulation contralateral to the DBS electrode in 6 patients. There was no difference in SEP amplitude and latency between on and off medication states. We also studied the high frequency oscillations (HFOs) by filtering the signal between 500 and 2,500 Hz. The HFOs could be identified only from contralateral stimulation and had intraburst frequencies of 1061 ± 121 Hz, onset latencies of 13.8 ± 1.2 milliseconds, and burst durations of 7.3 ± 1.1 milliseconds. Among the 10 recordings with HFOs, only 1 had possible phase reversal in the bipolar derivation. Our results suggest that there are direct somatosensory inputs to the PPNR. The slow components and HFOs of the SEP have different origins.

The integrative role of the pedunculopontine nucleus in human gait

“…These ascending projections may account for reports that PPN-DBS patients experience enhanced alertness during stimulation (Stefani et al, 2013). Such a function likely extends beyond the visual modality, as PPN neurons can also be modulated at short latency by auditory (Reese et al, 1995;Dormont et al, 1998), vestibular (Aravamuthan and Angelaki, 2012), nociceptive (Carlson et al, 2004) and somatosensory (Yeh et al, 2010) stimuli, suggesting that this structure integrates a variety of ongoing sensory information that may be useful for adapting locomotor behaviour to environmental demands (Rossignol et al, 2006). Further experiments are necessary to determine whether individual neurons integrate multimodal sensory information, and how these responses are related to preparatory, associative or cognitive processes linking sensory stimuli and movement.…”

Pedunculopontine Nucleus Region Deep Brain Stimulation in Parkinson Disease: Surgical Techniques, Side Effects, and Postoperative Imaging

“…Yeh et al [48] recorded somatosensory evoked potentials after median nerve stimulation. These were triphasic or biphasic potentials with latencies to the largest negative peak in the order of 16.8 and 18.7 ms.…”

Long-term follow-up of deep brain stimulation of peduncolopontine nucleus in progressive supranuclear palsy: Report of three cases

“…The heterogeneity in clinical outcome might be related to the topographic variability of the PPN and the degree of atrophy of the PPN and damage of interconnected basal ganglia structures. [53031] Further methodological diversity, such as single versus multiple target stimulation, targeting methods and consequently different anatomical location of implanted electrodes in the rostral brainstem may explain the different clinical results. [1213]…”