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Relaxation from a voluntary contraction is preceded by increased excitability of motor cortical inhibitory circuits.
No full textCreutzfeldt-Jakob disease presenting as corticobasal degeneration: a neurophysiological study
No full textCreutzfeldt-Jakob disease (CJD) can occasionally present with a clinical picture resembling a corticobasal degeneration (CBD). Transcallosal inhibition, as tested by focal transcranial magnetic stimulation, is frequently absent or highly disrupted in CBD patients. We report a case of CJD presenting at the beginning of the disease as a CBD in which the ipsilateral silent period (iSP) was present and well detectable. This brief report shows that study of the iSP may be a useful diagnostic tool in order to differentiate CBD from syndromes presenting with similar clinical features
Differential modulation of motor evoked potential and silent period by activation of intracortical inhibitory circuits.
No full textObjectives: To investigate the effect of activation of intracortical inhibitory circuits, as tested by short interval (3 ms) paired-pulse transcranial magnetic stimulation (TMS) with a conditioning-test paradigm, on the electromyographic (EMG) pause (silent period, SP) following the motor evoked potential (MEP) in normal subjects.
Methods: SPs and MEPs were recorded from the right first dorsal interosseous (FDI) muscle during a tonic voluntary contraction (from 70 to 90% of the maximum). Using a focal coil, we compared the SP duration after single-pulse TMS, paired-pulse TMS and single-pulse TMS of reduced intensity such as to evoke MEPs matched in size to the conditioned ones after paired-pulse TMS. In addition, we compared in a control experiment the duration of the SP following matched size MEPs evoked, respectively, by focal TMS with preferential activation of indirect I1- or I3-waves.
Results: SP duration after paired-pulse TMS was significantly longer than after single-pulse TMS evoking MEPs of a similar size. In no case the SP duration was longer when focal TMS preferentially activated I1-waves.
Conclusions: The conditioning sub-threshold stimulus is more powerful in reducing the MEP size than in cutting down the subsequent EMG silence, suggesting that the neural circuits underlying MEP and SP are, at least in part, different
Abnormalities of motor cortical excitability are not correlated with clinical features in atypical parkinsonism
No full textObjective: To evaluate the specificity of motor cortical excitability changes in parkinsonian syndromes and their relevance to the pathophysiology of cardinal parkinsonian features.
Methods: Paired transcranial magnetic stimulation (TMS) was used to assess cortico-cortical inhibition (CCI) and facilitation (CCF) in the opponens pollicis muscle of patients with atypical, non-L-dopa- (LD) responsive parkinsonism.
Results: Compared with age-matched normal control subjects, CCI (interstimulus interval [ISI], 3 ms) was significantly reduced in 10 patients with predominantly parkinsonian multiple system atrophy (MSA-P) and in seven with vascular parkinsonism (VP), but not in four with predominantly cerebellar MSA. No significant change of CCF (ISI, 12 ms) was observed. No correlation was found between the amount of CCI and clinical status as evaluated with the Unified Parkinson's Disease Rating Scale (UPDRS). In 10 patients (5 MSA-P, 5 VP), CCI was significantly increased by LD acute administration without concurrent clinical changes.
Conclusions: Abnormalities of CCI are not peculiar to idiopathic Parkinson's disease and seem unlikely to underlie any specific parkinsonian feature, but rather possibly reflect a nonspecific imbalance of inhibitory and facilitatory motor cortical circuits
Responses to transcran1al magnetic stimulation (TMS) in the masseter muscles of patients with amyotrophic lateral sclerosis (ALS)
No full textTMS of the motor cortex can document abnormalities of cortico-spinal system conductivity and excitability in ALS. The motor potentials evoked (MEPs) by TMS in muscles supplied by cranial nerves have not been extensively investigated in ALS, despite the frequent impairment of the bulbar region. We recorded MEPs from the masseter muscles of 30 ALS patients (16 M - 14 F; aged 42-86 ys.) as compared to 22 age-matched normal controls and 9 patients with spondylothic myelopathy. R-MEPs to direct stimulation of the trigeminal root were normal in ALS. Responses evoked by cortical stimulation in the preinnervated jaw-closing muscles (C-MEPs) were absent or delayed in 63.3% of ALS. Abnormalities of masseter CMEPs were observed in patients both with (77.8%) and without (41.7%) clinical bulbar signs. C-MEPs were normal in patients with spondylotic myelopathy. The investigation of corticobulbar projections may disclose frequent abnormalities in ALS, useful in the differential diagnosis between ALS and other spinal cord disorders
GEOGRAPHICAL ORIGIN AND BREED DISCRIMINATION OF APULIAN LAMB MEAT SAMPLES BY MEANS OF ANALYTICAL AND SPECTROSCOPIC DETERMINATIONS
No full textAbnormalities of sensorimotor integration in focal dystonia: a transcranial magnetic stimulation study
No full textIt has been postulated that sensorimotor integration is abnormal in dystonia. We investigated changes in motor cortical excitability induced by peripheral stimulation in patients with focal hand dystonia (12 patients with hand cramps) and with cervical dystonia (nine with spasmodic torticollis) compared with 16 age-matched normal controls. Motor evoked potentials (MEP) to focal (figure-of-eight coil) transcranial magnetic stimulation of the hand area were recorded from the right abductor pollicis brevis (APB), first dorsal interosseus (FDI), flexor carpi radialis and extensor carpi radialis muscles. Changes of test MEP size following conditioning stimulation of the right median nerve (or of the index finger) at conditioning-test (C-T) intervals of 50, 200, 600 and 1000 ms were analysed. Peripheral stimulation significantly reduced test MEP size in the APB and FDI muscles of normal control and spasmodic torticollis patients. The inhibitory effect was larger upon median nerve stimulation and reached a maximum at the C-T interval of 200 ms. On the contrary, hand cramp patients showed a significant facilitation of test MEP size. This study suggests that MEP suppression following peripheral stimulation is defective in patients with focal hand dystonia. Central processing of sensory input is abnormal in dystonia and may contribute to increased motor cortical excitability
Hydrogen peroxide LSPR sensing with unoxidised CuNPs-Tween® 60
No full textCopper nanoparticles (CuNPs) as well as those of other noble metals show unique features that are not observed in bulk copper. Despite the enormous potential of CuNPs, their use is limited by their susceptibility to oxidation during and after synthesis. Here, an innovative method based on wet synthesis protocol was developed to produce an aqueous colloidal solution of CuNPs capped with Tween® 60 (Polyoxyethylene sorbitan monostearate) capable of being stable and non-oxidised for several months. The CuNPs colloidal solution was tested for the detection of hydrogen peroxide (H2O2) showing a detection limit of 10–11 M. This result may provide the basis for the design of a rapid, practical, and easy-to-use colorimetric sensor to detect H2O2 in the future. Graphical abstract: [Figure not available: see fulltext.
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