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1.
Public Health ; 193: 126-138, 2021 Apr.
Article in English | MEDLINE | ID: mdl-33831694

ABSTRACT

OBJECTIVES: A systematic narrative literature review was undertaken to assess the acceptability of childhood screening interventions to identify factors to consider when planning or modifying childhood screening programs to maximize participation and uptake. STUDY DESIGN: This is a systematic narrative literature review. METHODS: Electronic databases were searched (MEDLINE, EMBASE, PsycINFO via Ovid, CINAHL, and Cochrane Library) to identify primary research studies that assessed screening acceptability. Studies were categorized using an existing theoretical framework of acceptability consisting of seven constructs: affective attitude, burden, ethicality, intervention coherence, opportunity costs, perceived effectiveness, and self-efficacy. A protocol was developed and registered with PROSPERO (registration no. CRD42018099763) RESULTS: The search identified 4529 studies, and 46 studies met the inclusion criteria. Most studies involved neonatal screening. Programs identified included newborn blood spot screening (n = 22), neonatal hearing screening (n = 13), Duchenne muscular dystrophy screening (n = 4), cystic fibrosis screening (n = 3), screening for congenital heart defects (n = 2), and others (n = 2). Most studies assessed more than one construct of acceptability. The most common constructs identified were affective attitude (how a parent feels about the program) and intervention coherence (parental understanding of the program, and/or the potential consequences of a confirmed diagnosis). CONCLUSIONS: The main acceptability component identified related to parental knowledge and understanding of the screening process, the testing procedure(s), and consent. The emotional impact of childhood screening mostly explored maternal anxiety. Further studies are needed to examine the acceptability of childhood screening across the wider family unit. When planning new (or refining existing) childhood screening programs, it is important to assess acceptability before implementation. This should include assessment of important issues such as information needs, timing of information, and when and where the screening should occur.


Subject(s)
Mass Screening , Parents/psychology , Patient Acceptance of Health Care/statistics & numerical data , Child , Humans , Infant , Infant, Newborn , Neonatal Screening
2.
Neurobiol Dis ; 128: 19-30, 2019 08.
Article in English | MEDLINE | ID: mdl-29524600

ABSTRACT

The interest in the pedunculopontine tegmental nucleus (PPTg), a structure located in the brainstem at the level of the pontomesencephalic junction, has greatly increased in recent years because it is involved in the regulation of physiological functions that fail in Parkinson's disease and because it is a promising target for deep brain stimulation in movement disorders. The PPTg is highly interconnected with the main basal ganglia nuclei and relays basal ganglia activity to thalamic and brainstem nuclei and to spinal effectors. In this review, we address the functional role of the main PPTg outputs directed to the basal ganglia, thalamus, cerebellum and spinal cord. Together, the data that we discuss show that the PPTg may influence thalamocortical activity and spinal motoneuron excitability through its ascending and descending output fibers, respectively. Cerebellar nuclei may also relay signals from the PPTg to thalamic and brainstem nuclei. In addition to participating in motor functions, the PPTg participates in arousal, attention, action selection and reward mechanisms. Finally, we discuss the possibility that the PPTg may be involved in excitotoxic degeneration of the dopaminergic neurons of the substantia nigra through the glutamatergic monosynaptic input that it provides to these neurons.


Subject(s)
Basal Ganglia/physiology , Neurons/physiology , Pedunculopontine Tegmental Nucleus/physiology , Animals , Attention/physiology , Humans , Neural Pathways/physiology , Reward
3.
J Appl Microbiol ; 125(1): 36-44, 2018 Jul.
Article in English | MEDLINE | ID: mdl-29573309

ABSTRACT

AIMS: To evaluate the survival of Mycobacterium avium subsp. paratuberculosis (MAP) during anaerobic digestion (AD), we studied two different biogas plants loaded with manure and slurry from paratuberculosis-infected dairy herds. METHODS AND RESULTS: Both plants were operating under mesophilic conditions, the first with a single digester and the second with a double digester. Mycobacterium avium subsp. paratuberculosis detection was performed by sampling each stage of the process, specifically the prefermenter, fermenter, liquid digestate and solid digestate stages, for 11 months. In both plants, MAP was isolated from the prefermenter stage. Only the final products, the solid and liquid digestates, of the one-stage plant showed viable MAP, while no viable MAP was detected in the digestates of the two-stage plant. CONCLUSIONS: Mycobacterium avium subsp. paratuberculosis showed a significant decrease during subsequent steps of the AD process, particularly in the two-stage plant. We suggest that the second digester maintained the digestate under anaerobic conditions for a longer period of time, thus reducing MAP survival and MAP load under the culture detection limit. SIGNIFICANCE AND IMPACT OF THE STUDY: Our data are unable to exclude the presence of MAP in the final products of the biogas plants, particularly those products from the single digester; therefore, the use of digestates as fertilizers is a real concern related to the possible environmental contamination with MAP.


Subject(s)
Biofuels , Bioreactors/microbiology , Mycobacterium avium subsp. paratuberculosis/isolation & purification , Plants/metabolism , Animals , Cattle , Manure/microbiology , Microbial Viability , Paratuberculosis/microbiology
4.
J Neural Transm (Vienna) ; 123(7): 737-750, 2016 07.
Article in English | MEDLINE | ID: mdl-27194228

ABSTRACT

The use of robotics in neurosurgery and, particularly, in stereotactic neurosurgery, is becoming more and more adopted because of the great advantages that it offers. Robotic manipulators easily allow to achieve great precision, reliability, and rapidity in the positioning of surgical instruments or devices in the brain. The aim of this work was to experimentally verify a fully automatic "no hands" surgical procedure. The integration of neuroimaging to data for planning the surgery, followed by application of new specific surgical tools, permitted the realization of a fully automated robotic implantation of leads in brain targets. An anthropomorphic commercial manipulator was utilized. In a preliminary phase, a software to plan surgery was developed, and the surgical tools were tested first during a simulation and then on a skull mock-up. In such a way, several tools were developed and tested, and the basis for an innovative surgical procedure arose. The final experimentation was carried out on anesthetized "large white" pigs. The determination of stereotactic parameters for the correct planning to reach the intended target was performed with the same technique currently employed in human stereotactic neurosurgery, and the robotic system revealed to be reliable and precise in reaching the target. The results of this work strengthen the possibility that a neurosurgeon may be substituted by a machine, and may represent the beginning of a new approach in the current clinical practice. Moreover, this possibility may have a great impact not only on stereotactic functional procedures but also on the entire domain of neurosurgery.


Subject(s)
Brain Diseases/surgery , Brain/surgery , Neurosurgery/instrumentation , Neurosurgery/methods , Robotics , Stereotaxic Techniques , Animals , Humans , Reproducibility of Results , Stereotaxic Techniques/instrumentation , Swine , Therapy, Computer-Assisted/instrumentation
5.
BMC Pulm Med ; 16: 16, 2016 Jan 22.
Article in English | MEDLINE | ID: mdl-26801409

ABSTRACT

BACKGROUND: The Lung Cancer Risk Test (LCRT) trial is a prospective cohort study comparing lung cancer incidence among persons with a positive or negative value for the LCRT, a 15 gene test measured in normal bronchial epithelial cells (NBEC). The purpose of this article is to describe the study design, primary endpoint, and safety; baseline characteristics of enrolled individuals; and establishment of a bio-specimen repository. METHODS/DESIGN: Eligible participants were aged 50-90 years, current or former smokers with 20 pack-years or more cigarette smoking history, free of lung cancer, and willing to undergo bronchoscopic brush biopsy for NBEC sample collection. NBEC, peripheral blood samples, baseline CT, and medical and demographic data were collected from each subject. DISCUSSION: Over a two-year span (2010-2012), 403 subjects were enrolled at 12 sites. At baseline 384 subjects remained in study and mean age and smoking history were 62.9 years and 50.4 pack-years respectively, with 34% current smokers. Obstructive lung disease (FEV1/FVC <0.7) was present in 157 (54%). No severe adverse events were associated with bronchoscopic brushing. An NBEC and matched peripheral blood bio-specimen repository was established. The demographic composition of the enrolled group is representative of the population for which the LCRT is intended. Specifically, based on baseline population characteristics we expect lung cancer incidence in this cohort to be representative of the population eligible for low-dose Computed Tomography (LDCT) lung cancer screening. Collection of NBEC by bronchial brush biopsy/bronchoscopy was safe and well-tolerated in this population. These findings support the feasibility of testing LCRT clinical utility in this prospective study. If validated, the LCRT has the potential to significantly narrow the population of individuals requiring annual low-dose helical CT screening for early detection of lung cancer and delay the onset of screening for individuals with results indicating low lung cancer risk. For these individuals, the small risk incurred by undergoing once in a lifetime bronchoscopic sample collection for LCRT may be offset by a reduction in their CT-related risks. The LCRT biospecimen repository will enable additional studies of genetic basis for COPD and/or lung cancer risk. TRIAL REGISTRATION: The LCRT Study, NCT 01130285, was registered with Clinicaltrials.gov on May 24, 2010.


Subject(s)
Epithelial Cells/metabolism , Lung Diseases, Obstructive/epidemiology , Lung Neoplasms/epidemiology , Occupational Exposure/statistics & numerical data , Smoking/epidemiology , Aged , Aged, 80 and over , Agriculture , Asbestos , Biological Specimen Banks , Bronchi/cytology , Bronchi/metabolism , Bronchoscopy , Cohort Studies , Early Detection of Cancer , Female , Forced Expiratory Volume , Genetic Predisposition to Disease , Humans , Incidence , Lung Diseases, Obstructive/physiopathology , Lung Neoplasms/diagnostic imaging , Lung Neoplasms/genetics , Male , Middle Aged , Prospective Studies , Respiratory Mucosa/cytology , Respiratory Mucosa/metabolism , Risk Assessment/methods , Tomography, Spiral Computed , Vital Capacity
6.
Neuroscience ; 317: 12-22, 2016 Mar 11.
Article in English | MEDLINE | ID: mdl-26762800

ABSTRACT

In spite of the existence of pedunculopontine tegmental nucleus (PPTg) projections to cerebellar nuclei, their nature and functional role is unknown. These fibers may play a crucial role in postural control and may be involved in the beneficial effects induced by deep-brain stimulation (DBS) of brainstem structures in motor disorders. We investigated the effects of PPTg microstimulation on single-unit activity of dentate, fastigial and interpositus nuclei. The effects of PPTg stimulation were also studied in rats whose PPTg neurons were destroyed by ibotenic acid and subsequently subjected to iontophoretically applied cholinergic antagonists. The main response recorded in cerebellar nuclei was a short-latency (1.5-2 ms) and brief (13-15 ms) orthodromic activation. The dentate nucleus was the most responsive to PPTg stimulation. The destruction of PPTg cells reduced the occurrence of PPTg-evoked activation of dentate neurons, suggesting that the effect was due to stimulation of cell bodies and not due to fibers passing through or close to the PPTg. Application of cholinergic antagonists reduced or eliminated the PPTg-evoked response recorded in the dentate nucleus. The results show that excitation is exerted by the PPTg on the cerebellar nuclei, in particular on the dentate nucleus. Taken together with the reduction of nicotinamide adenine dinucleotide phosphate-diaphorase-positive neurons in lesioned animals, the iontophoretic experiments suggest that the activation of dentate neurons is due to cholinergic fibers. These data help to explain the effects of DBS of the PPTg on axial motor disabilities in neurodegenerative disorders.


Subject(s)
Acetylcholine/metabolism , Cerebellar Nuclei/physiology , Neural Pathways/physiology , Neurons/drug effects , Pedunculopontine Tegmental Nucleus/cytology , Pedunculopontine Tegmental Nucleus/physiology , Action Potentials/drug effects , Animals , Biophysics , Cholinergic Agents/pharmacology , Cholinergic Fibers , Electric Stimulation , Iontophoresis , Male , NADPH Dehydrogenase/metabolism , Neurons/physiology , Patch-Clamp Techniques , Rats , Rats, Wistar , Reaction Time
7.
Gait Posture ; 40(3): 357-62, 2014 Jul.
Article in English | MEDLINE | ID: mdl-24908195

ABSTRACT

The pedunculopontine tegmental nucleus (PPTg) is a component of the locomotor mesencephalic area. In recent years it has been considered a new surgical site for deep brain stimulation (DBS) in movement disorders. Here, using objective kinematic and spatio-temporal gait analysis, we report the impact of low frequency (40 Hz) unilateral PPTg DBS in ten patients suffering from idiopathic Parkinson's disease with drug-resistant gait and axial disabilities. Patients were studied for gait initiation (GI) and steady-state level walking (LW) under residual drug therapy. In the LW study, a straight walking task was employed. Patients were compared with healthy age-matched controls. The analysis revealed that GI, cadence, stride length and left pelvic tilt range of motion (ROM) improved under stimulation. The duration of the S1 and S2 sub-phases of the anticipatory postural adjustment phase of GI was not affected by stimulation, however a significant improvement was observed in the S1 sub-phase in both the backward shift of centre of pressure and peak velocity. Speed during the swing phase, step width, stance duration, right pelvic tilt ROM phase, right and left hip flexion-extension ROM, and right and left knee ROM were not modified. Overall, the results show that unilateral PPTg DBS may affect GI and specific spatio-temporal and kinematic parameters during unconstrained walking on a straight trajectory, thus providing further support to the importance of the PPTg in the modulation of gait in neurodegenerative disorders.


Subject(s)
Deep Brain Stimulation/methods , Gait Disorders, Neurologic/physiopathology , Parkinson Disease/physiopathology , Pedunculopontine Tegmental Nucleus/physiology , Adult , Aged , Antiparkinson Agents/therapeutic use , Biomechanical Phenomena/drug effects , Case-Control Studies , Dopamine/therapeutic use , Drug Resistance , Gait Disorders, Neurologic/therapy , Humans , Male , Middle Aged , Parkinson Disease/therapy
8.
Vet Immunol Immunopathol ; 148(3-4): 369-72, 2012 Aug 15.
Article in English | MEDLINE | ID: mdl-22771195

ABSTRACT

Mycobacterium bovis recognizes as hosts a wide spectrum of animal species. In particular epidemiological situations, high prevalence of infection is found also in pigs. In the present study, we evaluated the capability of the interferon-gamma (IFN-γ) assay to identify pigs infected with M. bovis. The results of the immune-diagnosis were correlated to the findings of the post mortem inspection and the bacterial culture of lymph nodes. Blood samples of 146 pigs, belonging to a local breed of Sicily reared in free or semi-free roaming conditions, were collected to assess the specificity and the sensibility of the IFN-γ assay. Thirty-one pigs, from M. bovis free herds, did not react to the IFN-γ assay, yielding a specificity of 100%. The IFN-γ assay identified 15 out of 19 animals positive to the bacterial culture and 22 out of 26 animals with tuberculous lesions, with a sensibility of 78.9-84.6%, respectively. Out of 26 reactors to the test, 15 pigs (57.7%) confirmed to be infected after the bacterial culture and 22 (84.6%) had tuberculous lesions. The IFN-γ assay was able to reveal 4 animals with no visible lesions (NVL). Together, these findings support the feasible use of the IFN-γ assay as an intra vitam tool for the surveillance and management of M. bovis infection in swine populations.


Subject(s)
Interferon-gamma/blood , Swine Diseases/diagnosis , Tuberculosis/veterinary , Animals , Female , Male , Mycobacterium bovis , Sensitivity and Specificity , Swine/immunology , Swine/microbiology , Swine Diseases/blood , Swine Diseases/immunology , Swine Diseases/microbiology , Tuberculosis/blood , Tuberculosis/diagnosis , Tuberculosis/immunology
9.
J Neural Transm (Vienna) ; 118(10): 1477-86, 2011 Oct.
Article in English | MEDLINE | ID: mdl-21904896

ABSTRACT

In Parkinson's disease (PD), the effects of deep brain stimulation of the pedunculopontine nucleus (PPTg-DBS) on gait has been object of international debate. Some evidence demonstrated that, in the late swing-early stance phase of gait cycle, a reduced surface electromyographic activation (sEMG) of tibialis anterior (TA) is linked to the striatal dopamine deficiency in PD patients. In the present study we report preliminary results on the effect of PPTg-DBS on electromyographic patterns during gait in individual PD patients. To evaluate the sEMG amplitude of TA, the root mean square (RMS) of the TA burst in late swing-early stance phase (RMS-A) was normalized as a percent of the RMS of the TA burst in late stance-early swing (RMS-B). We studied three male patients in the following conditions: on PPTg-DBS/on L: -dopa, on PPTg-DBS/off L: -dopa, off PPTg-DBS/on L: -dopa, off PPTg-DBS/off L: -dopa. For each assessment the UPDRS III was filled in. We observed no difference between on PPTg-DBS/off L: -dopa and off PPTg-DBS/off L: -dopa in UPDRS III scores. In off PPTg-DBS/off L: -dopa, patient A (right implant) showed absence of the right and left RMSA, respectively, in 80% and 83% of gait cycles. Patient B (right implant) showed absence of the right RMS-A in 86% of cycles. RMS-A of the patient C (left implant) was bilaterally normal. In on PPTg- DBS/off L: -dopa, no patient showed reduced RMS-A. Although the very low number of subjects we evaluated, our observations suggest that PPTg plays a role in modulating TA activation pattern during the steady state of gait.


Subject(s)
Deep Brain Stimulation/methods , Evoked Potentials, Motor/physiology , Functional Laterality/physiology , Gait Disorders, Neurologic/etiology , Gait Disorders, Neurologic/therapy , Parkinson Disease/complications , Pedunculopontine Tegmental Nucleus/physiology , Aged , Electromyography , Humans , Imaging, Three-Dimensional , Magnetic Resonance Imaging , Male , Middle Aged , Muscle, Skeletal/physiopathology , Reaction Time/physiology
10.
J Neural Transm (Vienna) ; 118(10): 1423-9, 2011 Oct.
Article in English | MEDLINE | ID: mdl-21479864

ABSTRACT

The pedunculopontine nucleus (PPTg) is constituted by a heterogeneous cluster of neurons located in caudal mesencephalic tegmentum which projects to the thalamus to trigger thalamocortical rhythms and the brainstem to modulate muscle tone and locomotion. It has been investigated as potential deep brain stimulation (DBS) target for treating Parkinson's disease (PD) symptoms. Neurophysiological studies conducted in humans using DBS electrodes for exploring functional properties of PPTg in vivo, reviewed in this paper, demonstrated that the functional connections between PPTg and cortex, basal ganglia, brainstem network involved in sleep/wake control, and spinal cord can be explored in vivo and provided useful insights about the physiology of this nucleus and pathophysiology of PD.


Subject(s)
Neurons/physiology , Neurophysiology , Pedunculopontine Tegmental Nucleus/cytology , Pedunculopontine Tegmental Nucleus/physiology , Brain/anatomy & histology , Brain/physiology , Electroencephalography , Humans , Neural Pathways/physiology , Positron-Emission Tomography , Sleep, REM/physiology
11.
J Neural Transm (Vienna) ; 118(10): 1391-6, 2011 Oct.
Article in English | MEDLINE | ID: mdl-21188437

ABSTRACT

This issue is dedicated to a potential new target for the treatment of movement disorders, the pedunculopontine tegmental nucleus (PPTg), or, more simply, the pedunculopontine nucleus, that some authors abbreviate as PPN. We provide an overview of the field as an introduction to the general reader, beginning with the clinical experience to date of Mazzone and co-workers in Rome, some basic questions that need to be addressed, and potential future directions required in order to ensure that the potential benefits of this work are realized.


Subject(s)
Deep Brain Stimulation/methods , Deep Brain Stimulation/trends , Parkinson Disease/therapy , Pedunculopontine Tegmental Nucleus/physiology , Humans
13.
Brain Res ; 1287: 192-205, 2009 Sep 01.
Article in English | MEDLINE | ID: mdl-19539613

ABSTRACT

Active and passive tobacco smoke are associated with the dysfunction of endothelial physiology and vascular impairment. Studies correlating the effects of smoking and the brain microvasculature at the blood-brain barrier (BBB) level have been largely limited to few selective compounds that are present in the tobacco smoke (TS) yet the pathophysiology of smoking has not been unveiled. For this purpose, we characterized the physiological response of isolated human brain microvascular endothelial cells (HBMEC) and monocytes to the exposure of whole soluble TS extract. With the use of a well established humanized flow-based in vitro blood-brain barrier model (DIV-BBB) we have also investigated the BBB physiological response to TS under both normal and impaired hemodynamic conditions simulating ischemia. Our results showed that TS selectively decreased endothelial viability only at very high concentrations while not significantly affecting that of astrocytes and monocytes. At lower concentrations, despite the absence of cytotoxicity, TS induced a strong vascular pro-inflammatory response. This included the upregulation of endothelial pro-inflammatory genes, a significant increase of the levels of pro-inflammatory cytokines, activated matrix metalloproteinase, and the differentiation of monocytes into macrophages. When flow-cessation/reperfusion was paired with TS exposure, the inflammatory response and the loss of BBB viability were significantly increased in comparison to sham-smoke condition. In conclusion, TS is a strong vascular inflammatory primer that can facilitate the loss of BBB function and viability in pathological settings involving a local transient loss of cerebral blood flow such as during ischemic insults.


Subject(s)
Blood-Brain Barrier/physiopathology , Endothelium, Vascular/physiopathology , Microvessels/physiopathology , Tobacco Smoke Pollution/adverse effects , Vascular Diseases/etiology , Vascular Diseases/physiopathology , Blood-Brain Barrier/pathology , Blood-Brain Barrier/physiology , Cell Line, Tumor , Cell Survival/physiology , Cells, Cultured , Endothelium, Vascular/pathology , Endothelium, Vascular/physiology , Humans , Microvessels/pathology , Microvessels/physiology
14.
Exp Brain Res ; 194(4): 661-4, 2009 Apr.
Article in English | MEDLINE | ID: mdl-19319509

ABSTRACT

Paired associative stimulation (PAS), in which peripheral nerve stimuli are followed by transcranial magnetic stimulation (TMS) of the motor cortex, may produce a long lasting change in cortical excitability. At an interstimulus interval slightly shorter than the time needed for the afferent inputs to reach cerebral cortex (10 ms), motor cortex excitability decreases. Indirect data support the hypothesis that PAS at this interval (PAS10) involves LTD like-changes in cortical synapses. The aim of present paper was to investigate more directly PAS10 effects. We recorded corticospinal descending volleys evoked by single pulse TMS before and after PAS10 in two conscious subjects who had a high cervical epidural electrode implanted for pain control. These synchronous volleys provide a measure of cortical synaptic activity. PAS10 significantly reduced the amplitude of later descending waves while the earliest descending wave was not modified. Present results confirm the cortical origin of the effect of PAS10.


Subject(s)
Long-Term Synaptic Depression/physiology , Motor Cortex/physiology , Neuronal Plasticity/physiology , Electric Stimulation , Electrodes, Implanted , Evoked Potentials, Motor , Humans , Middle Aged , Transcranial Magnetic Stimulation , Ulnar Nerve/physiology
15.
Clin Neurophysiol ; 120(4): 834-9, 2009 Apr.
Article in English | MEDLINE | ID: mdl-19268631

ABSTRACT

OBJECTIVE: A loss of inhibition in central motor circuits resulting in abnormal motor control is the hypothesised cause of dystonia. So far, changes in inhibitory function of cerebral cortex in dystonia, have been revealed only indirectly by recording muscle responses evoked by transcranial magnetic stimulation (TMS) of the brain. The aim of present study was to evaluate more directly cerebral cortex changes in dystonia. We had the almost unique opportunity to record directly motor cortex output after brain stimulation, in a dystonic patient who had epidural electrodes implanted in the upper cervical cord. METHODS: We evaluated descending activity evoked by single and paired pulse TMS together with the inhibitory effects produced by afferent stimuli on TMS evoked activity, and compared the results with those obtained in thirteen subjects with no central nervous system abnormality who also had cervical spinal electrodes. RESULTS: The intrinsic inhibitory activity produced by paired TMS of the motor cortex, and the inhibitory effects produced by afferent inputs, were suppressed in the patient with dystonia. CONCLUSIONS: These findings provide a direct evidence of the abnormality in motor cortex inhibitory systems in dystonia. SIGNIFICANCE: The abnormality in cortical inhibitory system might have a role in the pathophysiology of dystonia.


Subject(s)
Cerebral Cortex/physiopathology , Dystonia/pathology , Dystonia/physiopathology , Neural Inhibition/physiology , Adult , Aged , Analysis of Variance , Biophysics , Electroencephalography , Evoked Potentials, Motor/physiology , Female , Humans , Middle Aged , Pyramidal Tracts/physiopathology , Reaction Time/physiology , Sensory Thresholds , Transcranial Magnetic Stimulation
16.
Cereb Cortex ; 19(10): 2326-30, 2009 Oct.
Article in English | MEDLINE | ID: mdl-19176639

ABSTRACT

Previous studies have shown that paired associative stimulation (PAS) protocol, in which peripheral nerve stimuli are followed by transcranial magnetic stimulation (TMS) of the motor cortex at intervals that produce an approximately synchronous activation of cortical networks, enhances the amplitude of motor evoked potentials (MEPs) evoked by cortical stimulation. Indirect data support the hypothesis that the enhancement of MEPs produced by PAS involves long-term potentiation like changes in cortical synapses. The aim of present paper was to investigate the central nervous system level at which PAS produces its effects. We recorded corticospinal descending volleys evoked by single pulse TMS of the motor cortex before and after PAS in 4 conscious subjects who had an electrode implanted in the cervical epidural space for the control of pain. The descending volleys evoked by TMS represent postsynaptic activity of corticospinal neurones that can provide indirect information about the effectiveness of synaptic inputs to these neurones. PAS significantly enhanced the amplitude of later descending waves, whereas the earliest descending wave was not significantly modified by PAS. The present results show that PAS may increase the amplitude of later corticospinal volleys, consistent with a cortical origin of the effect of PAS.


Subject(s)
Evoked Potentials, Motor/physiology , Motor Cortex/physiopathology , Neuronal Plasticity/physiology , Neurons/physiology , Pyramidal Tracts/physiopathology , Adult , Aged , Analysis of Variance , Electric Stimulation , Electrodes, Implanted , Electrophysiology , Female , Humans , Male , Middle Aged , Pain, Intractable/physiopathology , Signal Processing, Computer-Assisted , Transcranial Magnetic Stimulation
17.
Br J Neurosurg ; 22 Suppl 1: S33-40, 2008.
Article in English | MEDLINE | ID: mdl-19085351

ABSTRACT

The nucleus tegmenti pedunculopontine (PPTg) is a new target for deep brain stimulation (DBS) in Parkinson's disease (PD), in particular for ameliorating postural abnormalities and gait disturbances. The objective of the study is to describe the pre-operative planning, the surgical procedures and results of the DBS of PPTg in humans. Thirteen patients were considered. The surgical approach evolved from the traditional 'indirect' method based on stereotactic ventriculography (5 patients) to a more recent 'direct' method, based on both a digital elaboration of axial stereotactic CT scan and on the 'direct' visual 3D representation of the PPTg (8 patients). No major complication occurred. The direct approach allowed to eliminate the major sources of variability caused by the use of the traditional stereotactic approach. The DBS of PPTg induced a significant amelioration of the following clinical symptoms: gait disturbances, freezing on, speech and arising from the chair. These symptoms are usually not improved by levodopa treatment. The implantation of PPTg proved safe and effective in the treatment of levodopa resistant PD patients. The classic determination of stereotactic coordinates, through a proportional system based on ventriculography, utilising as landmark the CA-CP line and the top of the thalamus, and stereotactic atlases, can hardly be applied to brainstem surgery. The 'direct' method, based on both a digital elaboration of axial stereotactic CT scan and, on the 'direct' visualisation of brainstem borders as well as on the 3D representation of the PPTg, permits a better adaptation to individual anatomic features.


Subject(s)
Deep Brain Stimulation/methods , Parkinson Disease/surgery , Pedunculopontine Tegmental Nucleus/surgery , Pons/surgery , Aged , Female , Humans , Male , Middle Aged , Stereotaxic Techniques
18.
J Physiol ; 586(18): 4481-7, 2008 Sep 15.
Article in English | MEDLINE | ID: mdl-18653655

ABSTRACT

Previous studies have shown that low-frequency repetitive transcranial magnetic stimulation (rTMS) suppresses motor-evoked potentials (MEPs) evoked by single pulse TMS. The aim of the present paper was to investigate the central nervous system level at which rTMS produces a suppression of MEP amplitude. We recorded corticospinal volleys evoked by single pulse TMS of the motor cortex before and after 1 Hz rTMS in five conscious subjects who had an electrode implanted in the cervical epidural space for the control of pain. One of the patients had Parkinson's disease and was studied on medication. Repetitive TMS significantly suppressed the amplitude of later I-waves, and reduced the amplitude of concomitantly recorded MEPs. The earliest I-wave was not significantly modified by rTMS. The present results show that 1 Hz rTMS may decrease the amplitude of later descending waves, consistent with a cortical origin of the effect of 1 Hz rTMS on MEPs.


Subject(s)
Evoked Potentials, Motor , Motor Cortex/physiology , Transcranial Magnetic Stimulation , Adult , Aged , Aged, 80 and over , Humans , Middle Aged
19.
Eur J Neurosci ; 28(8): 1686-95, 2008 Oct.
Article in English | MEDLINE | ID: mdl-18657185

ABSTRACT

It is unclear how subthalamic nucleus activity is modulated by the cerebral cortex. Here we investigate the effect of transcranial magnetic stimulation (TMS) of the cortex on oscillatory subthalamic local field potential activity in the 8-35 Hz (alpha/beta) band, as exaggerated synchronization in this band is implicated in the pathophysiology of parkinsonism. We studied nine patients with Parkinson's disease (PD) to test whether cortical stimulation can modulate synchronized oscillations in the human subthalamic nucleus. With patients at rest, single-pulse TMS was delivered every 5 s over each primary motor area and supplementary motor area at intensities of 85-115% resting motor threshold. Subthalamic local field potentials were recorded from deep brain stimulation electrodes implanted into this nucleus for the treatment of PD. Motor cortical stimulation suppressed beta activity in the subthalamic nucleus from approximately 0.2 to 0.6 s after TMS (repeated measures anova; main effect of time, P < 0.01; main effect of side, P = 0.03), regardless of intensity. TMS over the supplementary motor area also reduced subthalamic beta activity at 95% (P = 0.05) and 115% resting motor threshold (P = 0.01). The oscillatory activity decreased to 80 +/- 26% of baseline (averaged across sites and stimulation intensities). Suppression with subthreshold stimuli confirmed that these changes were centrally driven and not due to peripheral afference. The results may have implications for mechanisms underlying the reported therapeutic benefits of cortical stimulation.


Subject(s)
Beta Rhythm , Biological Clocks/physiology , Motor Cortex/physiology , Neural Inhibition/physiology , Subthalamic Nucleus/physiology , Transcranial Magnetic Stimulation/methods , Action Potentials/physiology , Aged , Deep Brain Stimulation , Electrodes, Implanted , Evoked Potentials/physiology , Female , Humans , Male , Middle Aged , Motor Cortex/anatomy & histology , Neural Pathways/anatomy & histology , Neural Pathways/physiology , Neurons/physiology , Parkinson Disease/physiopathology , Parkinson Disease/therapy , Subthalamic Nucleus/anatomy & histology
20.
J Physiol ; 586(16): 3871-9, 2008 Aug 15.
Article in English | MEDLINE | ID: mdl-18566003

ABSTRACT

Theta burst stimulation (TBS) is a form of repetitive transcranial magnetic stimulation (TMS). When applied to motor cortex it leads to after-effects on corticospinal and corticocortical excitability that may reflect LTP/LTD-like synaptic effects. An inhibitory form of TBS (continuous, cTBS) suppresses MEPs, and spinal epidural recordings show this is due to suppression of the I1 volley evoked by TMS. Here we investigate whether the excitatory form of TBS (intermittent, iTBS) affects the same I-wave circuitry. We recorded corticospinal volleys evoked by single pulse TMS of the motor cortex before and after iTBS in three conscious patients who had an electrode implanted in the cervical epidural space for the control of pain. As in healthy subjects, iTBS increased MEPs, and this was accompanied by a significant increase in the amplitude of later I-waves, but not the I1 wave. In two of the patients we tested the excitability of the contralateral cortex and found a significant suppression of the late I-waves. The extent of the changes varied between the three patients, as did their age. To investigate whether age might be a significant contributor to the variability we examined the effect of iTBS on MEPs in 18 healthy subjects. iTBS facilitated MEPs evoked by TMS of the conditioned hemisphere and suppressed MEPs evoked by stimulation of the contralateral hemisphere. There was a slight but non-significant decline in MEP facilitation with age, suggesting that interindividual variability was more important than age in explaining our data. In a subgroup of 10 subjects we found that iTBS had no effect on the duration of the ipsilateral silent period suggesting that the reduction in contralateral MEPs was not due to an increase in ongoing transcallosal inhibition. In conclusion, iTBS affects the excitability of excitatory synaptic inputs to pyramidal tract neurones that are recruited by a TMS pulse, both in the stimulated hemisphere and in the contralateral hemisphere. However the circuits affected differ from those influenced by the inhibitory, cTBS, protocol. The implication is that cTBS and iTBS may have different therapeutic targets.


Subject(s)
Biological Clocks/physiology , Evoked Potentials, Motor/physiology , Long-Term Potentiation/physiology , Motor Cortex/physiology , Neuronal Plasticity/physiology , Pyramidal Tracts/physiology , Transcranial Magnetic Stimulation/methods , Aged , Aged, 80 and over , Female , Humans , Male , Middle Aged
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