Several Transcranial Magnetic Stimulation (TMS) techniques can be applied to noninvasively measure cortical excitability and brain plasticity in humans. TMS has been used to assess neuroplastic ...changes in Alzheimer's disease (AD), corroborating findings that cortical physiology is altered in AD due to the underlying neurodegenerative process. In fact, many TMS studies have provided physiological evidence of abnormalities in cortical excitability, connectivity, and plasticity in patients with AD. Moreover, the combination of TMS with other neurophysiological techniques, such as high‐density electroencephalography (EEG), makes it possible to study local and network cortical plasticity directly. Interestingly, several TMS studies revealed abnormalities in patients with early AD and even with mild cognitive impairment (MCI), thus enabling early identification of subjects in whom the cholinergic degeneration has occurred. Furthermore, TMS can influence brain function if delivered repetitively; repetitive TMS (rTMS) is capable of modulating cortical excitability and inducing long‐lasting neuroplastic changes. Preliminary findings have suggested that rTMS can enhance performances on several cognitive functions impaired in AD and MCI. However, further well‐controlled studies with appropriate methodology in larger patient cohorts are needed to replicate and extend the initial findings. The purpose of this paper was to provide an updated and comprehensive systematic review of the studies that have employed TMS/rTMS in patients with MCI and AD.
The OLYMPUS Collaboration reports on a precision measurement of the positron-proton to electron-proton elastic cross section ratio, R_{2γ}, a direct measure of the contribution of hard two-photon ...exchange to the elastic cross section. In the OLYMPUS measurement, 2.01 GeV electron and positron beams were directed through a hydrogen gas target internal to the DORIS storage ring at DESY. A toroidal magnetic spectrometer instrumented with drift chambers and time-of-flight scintillators detected elastically scattered leptons in coincidence with recoiling protons over a scattering angle range of ≈20° to 80°. The relative luminosity between the two beam species was monitored using tracking telescopes of interleaved gas electron multiplier and multiwire proportional chamber detectors at 12°, as well as symmetric Møller or Bhabha calorimeters at 1.29°. A total integrated luminosity of 4.5 fb^{-1} was collected. In the extraction of R_{2γ}, radiative effects were taken into account using a Monte Carlo generator to simulate the convolutions of internal bremsstrahlung with experiment-specific conditions such as detector acceptance and reconstruction efficiency. The resulting values of R_{2γ}, presented here for a wide range of virtual photon polarization 0.456<ε<0.978, are smaller than some hadronic two-photon exchange calculations predict, but are in reasonable agreement with a subtracted dispersion model and a phenomenological fit to the form factor data.
Background
Status epilepticus (SE) is a neurological emergency with high mortality and often a poor functional outcome amongst survivors. So far, only status epilepticus severity score (STESS) is ...available to predict individual outcomes. STESS is based on weighted sum scores of age, type of seizure, level of consciousness and history of previous seizures. Weighting factors were based on a priori assumptions.
Methods
We tested in an explorative, hypothesis generating approach, whether epidemiological data (i.e. mortality rates) can be combined to form a score (Epidemiology-based Mortality score in SE—EMSE), and further, which combination of aetiology, age, comorbidity, EEG, duration and level of consciousness yields highest test performance. Positive and negative predictive value, and correctly classified were compared to STESS (with different cut-off levels: STESS-3, STESS-4). Score points for each parameter, e.g. age, were derived from previously published specific mortality rates. For each combination of parameters, the lowest sum-score of deceased individuals was taken as cut-off. Ninety-two consecutive non-hypoxic patients (age range 20–90 years), with various forms of SE admitted to a tertiary care neurological intensive care unit were investigated retrospectively.
Results
EMSE using a combination of aetiology, age, comorbidity and EEG (NPV = 100 %, PPV = 68.8 %, correctly classified 89.1 %) was superior to STESS-3 and STESS-4 (
p
= 0.0022 or lower).
Conclusion
EMSE explained individual mortality in almost 90 % of cases, and performed significantly better than previous scores. This explorative study needs external prospective corroboration. EMSE may be a valuable tool for risk stratification in interventional studies in the future.
In this study we investigated the hypothesis whether P2-related differences tested in a visual priming paradigm are associated with theta phase-locking. We recorded the EEG from 31 electrodes and ...calculated phase-locking index and total power differences for frequencies between 2 and 20
Hz. ERPs (event-related potentials) were analyzed for P1, N1 and P2 components. P2 showed strongest task-related amplitude differences between congruent and incongruent targets. A source analyses was performed for the P2 component using sLoreta that revealed local generators of the P2 in parieto–occipital regions. Phase-locking analyses showed specific effects in the theta range (4–6
Hz) appearing in time windows at around the P2 component. We draw the conclusion that phase-locked theta reflect top-down regulation processes mediating information between memory systems and is in part involved in the modulation of the P2 component.
Repetitive transcranial magnetic stimulation study.
The analgesic effects of repetitive transcranial magnetic stimulation (rTMS) in chronic pain have been the focus of several studies. In particular, ...rTMS of the premotor cortex/dorsolateral prefrontal cortex (PMC/DLPFC) changes pain perception in healthy subjects and has analgesic effects in acute postoperative pain, as well as in fibromyalgia patients. However, its effect on neuropathic pain in patients with traumatic spinal cord injury (SCI) has not been assessed.
Merano (Italy) and Salzburg (Austria).
In this study, we performed PMC/DLPFC rTMS in subjects with SCI and neuropathic pain. Twelve subjects with chronic cervical or thoracic SCI were randomized to receive 1250 pulses at 10 Hz rTMS (n=6) or sham rTMS (n=6) treatment for 10 sessions over 2 weeks. The visual analog scale, the sensory and affective pain rating indices of the McGill Pain Questionnaire (MPQ), the Hamilton Depression Rating Scale and the Hamilton Anxiety Rating Scale were used to assed pain and mood at baseline (T0), 1 day after the first week of treatment (T1), 1 day (T2), 1 week (T3) and 1 month (T4) after the last intervention.
Subjects who received active rTMS had a statistically significant reduction in pain symptoms in comparison with their baseline pain, whereas sham rTMS participants had a non-significant change in daily pain from their baseline pain.
The findings of this preliminary study in a small patient sample suggest that rTMS of the PMC/DLPFC may be effective in relieving neuropathic pain in SCI patients.
A
bstract
A comprehensive set of azimuthal single-spin and double-spin asymmetries in semi-inclusive leptoproduction of pions, charged kaons, protons, and antiprotons from transversely polarized ...protons is presented. These asymmetries include the previously published HERMES results on Collins and Sivers asymmetries, the analysis of which has been extended to include protons and antiprotons and also to an extraction in a three-dimensional kinematic binning and enlarged phase space. They are complemented by corresponding results for the remaining four single-spin and four double-spin asymmetries allowed in the one-photon-exchange approximation of the semi-inclusive deep-inelastic scattering process for target-polarization orientation perpendicular to the direction of the incoming lepton beam. Among those results, significant non-vanishing cos (
ϕ−ϕ
S
) modulations provide evidence for a sizable worm-gear (II) distribution,
g
1
T
q
x
p
T
2
. Most of the other modulations are found to be consistent with zero with the notable exception of large sin (
ϕ
S
) modulations for charged pions and
K
+
.
Azimuthal single-spin asymmetries of leptoproduced pions and charged kaons were measured on a transversely polarized hydrogen target. Evidence for a naive-T-odd, transverse-momentum-dependent parton ...distribution function is deduced from nonvanishing Sivers effects for pi(+), pi(0), and K(+/-), as well as in the difference of the pi(+) and pi(-) cross sections.
Topical review of the literature.
The objective of this review article was to assess indications and usefulness of various neurophysiological techniques in diagnosis and management of cervical ...spondylogenic myelopathy (CSM).
The MEDLINE, accessed by Pubmed and EMBASE electronic databases, was searched using the medical subject headings: 'compressive myelopathy', 'cervical spondylotic myelopathy (CSM)', 'cervical spondylogenic myelopathy', 'motor evoked potentials (MEPs)', 'transcranial magnetic stimulation', 'somatosensory evoked potentials (SEPs)', 'electromyography (EMG)', 'nerve conduction studies (NCS)' and 'cutaneous silent period (CSP)'.
SEPs and MEPs recording can usefully supplement clinical examination and neuroimaging findings in assessing the spinal cord injury level and severity. Segmental cervical cord dysfunction can be revealed by an abnormal spinal N13 response, whereas the P14 potential is a reliable marker of dorsal column impairment. MEPs may also help in the differential diagnosis between spinal cord compression and neurodegenerative disorders. SEPs and MEPs are also useful in follow-up evaluation of sensory and motor function during surgical treatment and rehabilitation. EMG and NCS improve the sensitivity of cervical radiculopathy detection and may help rule out peripheral nerve problems that can cause symptoms that are similar to those of CSM. CSP also shows a high sensitivity for detecting CSM.
Neuroimaging, especially magnetic resonance imaging, represents the procedure of choice for the diagnosis of CSM, but a correct interpretation of morphological findings can be achieved only if they are correlated with functional data. The studies reported in this review highlight the crucial role of the electrophysiological studies in diagnosis and management of CSM.
Randomized, double-blind, crossover, sham-controlled trial.
Repetitive transcranial magnetic stimulation (rTMS) over the primary motor cortex (M1) leads to a significant reduction of spasticity in ...subjects with spinal cord injury (SCI), but the physiological basis of this effect is still not well understood. The purpose of this study was to evaluate the disynaptic reciprocal Ia inhibition of soleus motoneurons in SCI patients.
Department of Neurology, Merano, Italy and TMS Laboratory, Paracelsus Medical University, Salzburg, Austria.
Nine subjects with incomplete cervical or thoracic SCI received 5 days of daily sessions of real or sham rTMS applied over the contralateral M1. We compared the reciprocal inhibition, the Modified Ashworth Scale and the Spinal Cord Injury Assessment Tool for Spasticity at baseline, after the last session and 1 week later in the real rTMS and sham stimulation groups.
We found that real rTMS significantly reduced lower limb spasticity and restored the impaired excitability in the disynaptic reciprocal inhibitory pathway.
In a small proof-of-concept study, rTMS strengthened descending projections between the motor cortex and inhibitory spinal interneuronal circuits. This reversed a defect in reciprocal inhibition after SCI, and reduced leg spasticity.
We report the first measurement of the average of the electron-proton and positron-proton elastic scattering cross sections. This lepton charge-averaged cross section is insensitive to the leading ...effects of hard two-photon exchange, giving more robust access to the proton's electromagnetic form factors. The cross section was extracted from data taken by the OLYMPUS experiment at DESY, in which alternating stored electron and positron beams were scattered from a windowless gaseous hydrogen target. Elastic scattering events were identified from the coincident detection of the scattered lepton and recoil proton in a large-acceptance toroidal spectrometer. The luminosity was determined from the rates of Møller, Bhabha, and elastic scattering in forward electromagnetic calorimeters. The data provide some selectivity between existing form factor global fits and will provide valuable constraints to future fits.
PDF
