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• Both muscular and cutaneous somatosensory input arrives at the cuneate nucleus. • Muscle somatosensory input dose not evoke any low-frequency response from the cuneate nucleus. • Subcortical high-frequency oscillations include both presynaptic and postsynaptic components. To investigate the subcortical somatosensory evoked potentials (SEPs) to electrical stimulation of either muscle or cutaneous afferents. SEPs were recorded in 6 patients suffering from Parkinson's disease (PD) who underwent electrode implantation in the pedunculopontine (PPTg) nucleus area. We compared SEPs recorded from the scalp and from the intracranial electrode contacts to electrical stimuli applied to: 1) median nerve at the wrist, 2) abductor pollicis brevis motor point, and 3) distal phalanx of the thumb. Also the high-frequency oscillations (HFOs) were analysed. After median nerve and pure cutaneous (distant phalanx of the thumb) stimulation, a P1-N1 complex was recorded by the intracranial lead, while the scalp electrodes recorded the short-latency far-field responses (P14 and N18). On the contrary, motor point stimulation did not evoke any low-frequency component in the PPTg traces, nor the N18 potential on the scalp. HFOs were recorded to stimulation of all modalities by the PPTg electrode contacts. Stimulus processing within the cuneate nucleus depends on modality, since only the cutaneous input activates the complex intranuclear network possibly generating the scalp N18 potential. Our results shed light on the subcortical processing of the somatosensory input of different modalities. [ABSTRACT FROM AUTHOR]

• Single stimuli applied to the pedunculopontine tegmental nucleus (PPTg) modulate the blink reflex (BR) in Parkinson's disease. • The action of the PPTg on the BR differs from the action exerted by other basal ganglia nuclei. • The PPTg has a critical role in the pathway mediating the prepulse inhibition of the BR. To investigate the effects on the blink reflex (BR) of single stimuli applied to the pedunculopontine tegmental nucleus (PPTg). The BR was evoked by stimulating the supraorbital nerve (SON) in fifteen patients suffering from idiopathic Parkinson's disease (PD) who had electrodes monolaterally or bilaterally implanted in the PPTg for deep brain stimulation (DBS). Single stimuli were delivered to the PPTg through externalized electrode connection wires 3–4 days following PPTg implantation. PPTg stimuli increased the latency and reduced duration, amplitude and area of the R2 component of the BR in comparison to the response recorded in the absence of PPTg stimulation. These effects were independent of the side of SON stimulation and were stable for interstimulus interval (ISI) between PPTg prepulse and SON stimulus from 0 to 110 ms. The PPTg-induced prepulse inhibition of the BR was bilaterally present in the brainstem. The R1 component was unaffected. The prepulse inhibition of the R2 component may be modulated by the PPTg. These findings suggest that abnormalities of BR occurring in PD may be ascribed to a reduction of basal ganglia-mediated inhibition of brainstem excitability. [ABSTRACT FROM AUTHOR]

Abstract: Fourteen patients, suffering from chronic pain resistant to pharmacological treatment, underwent epidural electrode implant on the cervical spinal cord (CSC) for neuromodulation. After the median nerve stimulation, somatosensory evoked potentials (SEPs) were recorded from the epidural electrode contacts, from the frontal and the parietal regions contralateral to the stimulated side, from an electrode placed over the sixth cervical vertebra and from the Erb''s point. SEPs were recorded at rest and during a voluntary flexion–extension movement of the stimulated wrist. The epidural electrode contacts recorded a triphasic potential (P1–N1–P2). The epidural potential amplitude was significantly decreased during voluntary movement compared with the rest, thus suggesting that the effect of movement on SEPs occurs also at CSC level. [Copyright &y& Elsevier]

Objectives The study aimed to investigate the site of the movement related inhibition of the human dorsal column nuclei. Methods Median nerve somatosensory evoked potentials (SEPs) were recorded from 18 patients suffering from Parkinson’s disease, who underwent electrode implantation in the pedunculopontine (PPTg) nucleus. SEPs were recorded at rest and during active or passive movement of the thumb of the stimulated wrist. Results The PPTg electrode recorded a triphasic potential generated in the cuneate nucleus. The PPTg potential was subtended by 2 high frequency oscillation (HFO) components: (1) an earlier one with 1000 Hz frequency and (2) a later one with 1700 Hz frequency. Both HFO components were reduced by movement. No major difference between the effects of either active or passive movement was found. Discussion PPTg electrode can record SEPs generated in the dorsal column nuclei (DCN). We suggest that the 1000 Hz and 1700 Hz HFO bursts are generated at pre- and post-synaptical level, respectively. Conclusion Movement exerts both pre- and post-synaptic inhibition on dorsal column nuclei. Significance Investigating the effect of movement on the DCN activity by an intracerebral electrode located at the human PPTg level confirms what early studies in animals suggested. [ABSTRACT FROM AUTHOR]

Objectives To investigate the effect of pure passive movement on both cortical and subcortical somatosensory evoked potentials (SEPs). Methods Median nerve SEPs were recorded in 8 patients suffering from Parkinson’s disease (PD) and two patients with essential tremor. PD patients underwent electrode implantation in the subthalamic (STN) nucleus (3 patients) and pedunculopontine (PPTg) nucleus (5 patients), while 2 patients with essential tremor were implanted in the ventral intermediate nucleus (VIM) of the thalamus. In anesthetized patients, SEPs were recorded at rest and during a passive movement of the thumb of the stimulated wrist from the intracranial electrode contacts and from the scalp. Also the high-frequency oscillations (HFOs) were analyzed. Results Amplitudes of both deep and scalp components were decreased during passive movement, but the reduction was higher at cortical than subcortical level. Also the HFOs were reduced by movement. Conclusion The different amount of the movement-related decrease suggests that the cortical SEP gating is not only the result of a subcortical somatosensory volley attenuation, but a further mechanism acting at cortical level should be considered. Significance Our results are important for understanding the physiological mechanism of the sensory–motor interaction during passive movement. [ABSTRACT FROM AUTHOR]

Objective To investigate the generators of the somatosensory evoked potential (SEP) components recorded from the Pedunculopontine Tegmental nucleus (PPTg). Methods Twenty-two patients, suffering from Parkinson’s disease (PD), underwent electrode implantation in the PPTg area for deep brain stimulation (DBS). SEPs were recorded from the DBS electrode contacts to median nerve stimulation. Results SEPs recorded from the PPTg electrode contacts could be classified in 3 types, according to their waveforms. (1) The biphasic potential showed a positive peak (P16) whose latency (16.05 ± 0.61 ms) shifted of 0.18 ± 0.07 ms from the lower to the upper contact of the electrode. (2) The triphasic potential showed an initial positive peak (P15) whose latency (15.4 ± 0.2 ms) did not change across the DBS electrode contacts. (3) In the last SEP configuration (mixed biphasic and triphasic waveform), the positive peak was bifid including both the P15 and P16 potentials. Conclusion While the P16 potential is probably generated by the somatosensory volley travelling along the medial lemniscus, the P15 response represents a far-field potential probably generated at the cuneate nucleus level. Significance Our results show the physiological meaning of the somatosensory responses recorded from the PPTg nucleus area. [ABSTRACT FROM AUTHOR]

Abstract: Objective: To investigate the effect of the voluntary movement on the amplitude of the somatosensory evoked potentials (SEPs) recorded by an epidural electrode at level of the dorsal column nuclei (DCN). Methods: Five patients, suffering from chronic pain resistant to pharmacological treatment, underwent an epidural electrode implant at high cervical spinal cord level (C2) for neuromodulation. After tibial nerve stimulation, SEPs were recorded from the epidural electrode contacts, from a Cz lead, and from two electrodes placed over the 12th dorsal vertebra and 4th lumbar vertebra, respectively. SEPs were recorded at rest and during a voluntary flexo-extension movement of the stimulated foot. Beyond the low-frequency SEPs, also the high-frequency oscillations (HFOs), obtained by filtering the recorded traces by means of a 1000–2000Hz bandpass offline, were analysed. Results: The epidural electrode contacts recorded a triphasic potential (P1–N1–P2), whose negative peak showed a latency similar to that of the P30 far-field response obtained from the scalp. The epidural potential amplitude was significantly decreased by the voluntary movement, as compared to the rest (p <0.01). A main HFO peak, identifiable at around 1200Hz, was significantly lower in amplitude during movement than at rest (p =0.008). Conclusions: Our findings suggest that the epidural C2 triphasic wave is a potential arising from DCN. The low-frequency epidural SEP component is subtended by a 1200Hz HFO, probably generated by post-synaptic events. Significance: The amplitude reduction of the DCN response during movement is possibly due to decreased excitability of the DCN neurons receiving the somatosensory ascending input. [Copyright &y& Elsevier]

Abstract: Objective: To investigate the effect of the voluntary movement on the amplitude of the somatosensory evoked potentials (SEPs) recorded by an epidural electrode at level of the cervical spinal cord (CSC). Methods: Fourteen patients underwent an epidural electrode implant at CSC level for pain relief. After the median nerve stimulation, SEPs were recorded from the epidural electrode and from 4 surface electrodes (in frontal and parietal regions contralateral to the stimulated side, over the 6th cervical vertebra, and on the Erb’s point). SEPs were recorded at rest and during a voluntary flexo-extension movement of the stimulated wrist. Beyond the low-frequency SEPs, also the high-frequency oscillations (HFOs) were analysed. Results: The epidural electrode contacts recorded a triphasic potential (P1–N1–P2), whose negative peak showed the same latency as the cervical N13 response. The epidural potential amplitude was significantly decreased during the voluntary movement, as compared to the rest. Two main HFOs were identifiable: (1) the 1200Hz HFO which was significantly lower in amplitude during movement than at rest, and (2) the 500Hz HFO which was not modified by the voluntary movement. Conclusions: The low-frequency cervical SEP component is subtended by HFOs probably generated by: (1) postsynaptic potentials in the dorsal horn neurones (1200Hz), and (2) presynaptic ascending somatosensory inputs (500Hz). Significance: Our findings show that the voluntary movement may affect the somatosensory input processing also at CSC level. [Copyright &y& Elsevier]

Background: Contemporary definitions of bleeding endpoints are restricted mostly to clinically overt events. Whether hemoglobin drop per se, with or without overt bleeding, adversely affects the prognosis of patients with acute coronary syndrome (ACS) remains unclear.Objectives: The aim of this study was to examine in the MATRIX (Minimizing Adverse Haemorrhagic Events by Transradial Access Site and Systemic Implementation of Angiox) trial the incidence, predictors, and prognostic implications of in-hospital hemoglobin drop in patients with ACS managed invasively stratified by the presence of in-hospital bleeding.Methods: Patients were categorized by the presence and amount of in-hospital hemoglobin drop on the basis of baseline and nadir hemoglobin values and further stratified by the occurrence of adjudicated in-hospital bleeding. Hemoglobin drop was defined as minimal (<3 g/dl), minor (≥3 and <5 g/dl), or major (≥5 g/dl). Using multivariate Cox regression, we modeled the association between hemoglobin drop and mortality in patients with and without overt bleeding.Results: Among 7,781 patients alive 24 h after randomization with available hemoglobin data, 6,504 patients (83.6%) had hemoglobin drop, of whom 5,756 (88.5%) did not have overt bleeding and 748 (11.5%) had overt bleeding. Among patients without overt bleeding, minor (hazard ratio [HR]: 2.37; 95% confidence interval [CI]: 1.32 to 4.24; p = 0.004) and major (HR: 2.58; 95% CI: 0.98 to 6.78; p = 0.054) hemoglobin drop were independently associated with higher 1-year mortality. Among patients with overt bleeding, the association of minor and major hemoglobin drop with 1-year mortality was directionally similar but had wider CIs (minor: HR: 3.53 [95% CI: 1.06 to 11.79]; major: HR: 13.32 [95% CI: 3.01 to 58.98]).Conclusions: Among patients with ACS managed invasively, in-hospital hemoglobin drop ≥3 g/dl, even in the absence of overt bleeding, is common and is independently associated with increased risk for 1-year mortality. (Minimizing Adverse Haemorrhagic Events by Transradial Access Site and Systemic Implementation of Angiox; NCT01433627). [ABSTRACT FROM AUTHOR]

The pedunculopontine tegmental nucleus (PPTg) relays basal ganglia signals to the thalamus, lower brainstem and spinal cord. Using the 6-hydroxydopamine (6-OHDA) rat model of parkinsonism, we investigated whether deep brain stimulation (DBS) of the PPTg (40Hz, 60μs, 200-400μA) may influence the preparative and executive phases in a conditioned behavioural task, and the motor asymmetries induced by apomorphine. In the conditioned task, rats had to press two levers according to a fixed delay paradigm. The 6-OHDA lesion was placed in the right medial forebrain bundle, i.e. contralaterally to the preferred forepaw used by rats to press levers in the adopted task. The stimulating electrode was implanted in the right PPTg, i.e. contralateral to left side, which was expected to be most affected. The lesion significantly reduced correct responses from 63.4% to 16.6%. PPTg-DBS effects were episodic; however, when rats successfully performed in the task (18.9%), reaction time (468.8±36.5ms) was significantly increased (589.9±45.9ms), but not improved by PPTg-DBS (646.7±33.8ms). Movement time was significantly increased following the lesion (649.2±42.6ms vs. 810.9±53.0ms), but significantly reduced by PPTg-DBS (820.4±39.4ms) compared to sham PPTg-DBS (979.8±47.6ms). In a second group of lesioned rats, rotations induced by apomorphine were significantly reduced by PPTg-DBS compared to sham PPTg-DBS (12.2±0.6 vs. 9.5±0.4 mean turns/min). Thus, it appears that specific aspects of motor deficits in 6-OHDA-lesioned rats may be modulated by PPTg-DBS. [ABSTRACT FROM AUTHOR]

Abstract: The present paper was aimed at investigating the effect of low-frequency electrical stimulation (25 Hz) of the peduncolopontine (PPN) area on working memory (WM) functioning in patients with Parkinson''s disease (PD). Five PD patients who underwent simultaneous PPN area- and subthalamic nucleus-deep brain stimulation (DBS) implantation participated in the study. PD patients were evaluated in the morning at least 12 h after antiparkinsonian therapy withdrawal in two conditions: i) after continuous PPN area stimulation (Off Therapy/On PPN: “On” condition); ii) at least 120 min after PPN area had been switched “Off” (Off Ther/Off PPN: “Off” condition). The experimental WM task consisted of an n-back paradigm with verbal and visual-object stimuli. PD patients showed a consistent response time decrease on both the verbal and the visual-object tasks passing from the “Off” to the “On” condition (p < 0.05). However, the accuracy score did not significantly differ between the two experimental conditions. The present findings, although preliminary, suggest that PPN area stimulation facilitates the speed processing of information in the content of WM, possibly through the modulation of the attentional resources. [Copyright &y& Elsevier]

Abstract: Combined deep brain stimulation of the subthalamic (STN) and pedunculopontine (PPN) nuclei has been recently proposed as surgical treatment of advanced Parkinson''s disease. STN stimulation alone has been shown to provide selective improvement of the grammatical aspect of language. We studied five advanced Parkinson''s disease patients who underwent combined deep brain stimulation (STN + PPN). Overall cognitive profile did not change. On the contrary, an interesting trend towards reduction of ungrammatical errors (particularly substitution of free and inflectional morphemes) was found when stimulating the STN, and also the PPN, when the STN was switched off. These findings replicate previous observations on the STN, and provide the rationale for further investigation of the role of the PPN in processing linguistic grammar. [Copyright &y& Elsevier]

Abstract: Objective: To investigate whether recording from deep intracerebral (IC) electrodes can disclose laser evoked potential (LEP) components generated under the cerebral cortex. Methods: LEPs were recorded to hand and/or perioral region stimulation from 7 patients suffering from Parkinson’s disease, who underwent implant of IC electrodes in the globus pallidum pars interna (GPi), in the subthalamic nucleus (STN) and in the pedunculopontine nucleus (PPN). LEPs were obtained from the IC electrode contacts and from the Cz vertex, referred to the nose. Results: The scalp traces showed a triphasic response (P1-N2-P2). The IC electrodes recorded two main components (ICP2 and ICN2), showing the same latencies as the scalp N2 and P2 potentials, respectively. The ICP2-ICN2 complex was sometimes preceded by a ICP1 wave at the same latency of the scalp P1 response. Conclusions: The LEP components recorded from the IC electrodes mirrored the ones picked up from the Cz lead, thus suggesting that they are probably generated by the opposite pole of the same cortical sources producing the scalp responses. Significance: In the IC traces, there was no evidence of earlier potentials possibly generated within the thalamus or of subcortical far-field responses. This means that the nociceptive signal amplification occurring within the cerebral cortex is necessary to produce identifiable LEP components. [Copyright &y& Elsevier]

Abstract: The intra-laminar (IL) thalamic complex, composed of centromedian (CM) and parafascicular (Pf) nucleus, is a strategic crossroad for the activity of the basal ganglia and is recently regaining its position has a putative neurosurgical target for Parkinsonian syndromes. The multi-target approach we have encouraged since the late nineties has allowed the combined implantation of a standard target (the subthalamic nucleus—STN or the internal pallidus—GPi) plus an innovative one (CM/Pf) in well-identified Parkinson’s disease (PD) patients; hence, it is possible to study, in the same PD patients, the specific target-mediated effects on different clinical signs. Here, we focus on the potential usefulness of implanting the CM/Pf complex when required in the management of contra-lateral tremor (resistant to standard deep brain stimulation—DBS – in STN – , n =2) and disabling involuntary movements, partially responsive to GPi–DBS (n =6). When considering global UPDRS scores, CM/Pf–DBS ameliorate extra-pyramidal symptoms but not as strongly as STN (or GPi) does. Yet, CM/Pf acts very powerfully on tremor and contributes to the long-term management of l-Dopa-induced involuntary movements. The lack of cognitive deficits and psychic impairment associated with the improvement of their quality of life, in our small cohort of CM/Pf implanted patients, reinforces the notion of CM/Pf as a safe and attractive area for surgical treatment of advanced PD, possibly affecting not only motor but also associative functions. [Copyright &y& Elsevier]

Objective: To investigate whether the reduction of amplitude of the scalp somatosensory evoked potentials (SEPs) during movement (gating) is due to an attenuation of the afferent volley at subcortical level.Methods: Median nerve SEPs were recorded from 9 patients suffering from Parkinson''s disease, who underwent implant of intracerebral (IC) electrodes in the subthalamic nucleus or in the globus pallidum. SEPs were recorded from Erb''s point ipsilateral to stimulation, from the scalp surface and from the IC leads, at rest and during a voluntary flexo-extension movement of the stimulated wrist. The recorded IC traces were submitted to an off-line filtering by a 300–1500 bandpass to obtain the high-frequency SEP bursts.Results: IC leads recorded a triphasic component (P1–N1–P2) from 14 to 22 ms of latency. The amplitudes of the scalp N20, P20 and N30 potentials and of the IC triphasic component were significantly decreased during movement, while the peripheral N9 amplitude remained unchanged. Also the IC bursts, whose frequency was around 1000 Hz, were reduced in amplitude by the voluntary movement.Conclusions: Since the IC triphasic component is probably generated by neurons of the thalamic ventro-postero-lateral nucleus, which receive the somatosensory afferent volley, the P1–N1 amplitude reduction during movement suggests that the gating phenomenon involves also the subcortical structures. [Copyright &y& Elsevier]

Here we seek to establish whether there are activities in the human pallidum that may predict a specific aspect of performance, timing. When recording from two patients with Parkinson''s disease and primary generalised dystonia following functional neurosurgery we found that the amplitude of oscillatory pallidal activity occurring prior to the completion of a bimanual timing task was strongly correlated with eventual task duration. The frequency of this oscillatory activity was around 25 Hz. We conclude that the human pallidum may be involved in the prediction of movement timings and that such internal estimates may be reflected in amplitude modulation of oscillatory activity around 25 Hz. [Copyright &y& Elsevier]