Hemispheric lateralization of the corticostriatal glutamatergic system in the rat

Little is known about hemispheric lateralization of subcortical structures. Here, we show a higher expression of the subunit NR2A of the NMDA receptor mRNA in the striatum and of vGluT1 mRNA in the cingulate cortex, in the left hemisphere compared to the right one. This suggests a lateralization of the glutamatergic cortico-subcortical system, at the level of postsynaptic receptors as well as at the level of corticostriatal projections. Such lateralization could play a role in asymmetric diseases like Parkinson's diseas

Monoclonal gammopathy missed by capillary zone electrophoresis

Background: Serum protein electrophoresis is used as a screening test for monoclonal gammopathies. Here, we present a case of a high-concentration monoclonal immunoglobulin (M-protein) that was missed by serum protein electrophoresis on a Capillarys 2 capillary zone electrophoresis system. The aim of our study was to identify the reason for the failure of the system to detect the M-protein. Methods: M-protein solubility was examined in response to temperature, pH, ionic strength, the chaotropic agent urea and the reducing agent 2-mercaptoethanol. Results: Precipitation of the M-protein was not cold-induced, but solubility decreased at pH 8.5 or higher, when the pH approached the apparent isoelectric point. The M-protein also precipitated in alkaline Capillarys 2 electrophoresis buffer (pH 10), which was the reason for the false-negative electrophoresis result. Precipitation of the M-protein was not related to the ionic strength of the buffer. Solubility improved in presence of urea. Pre-treatment of serum with 2-mercaptoethanol revealed the missing M-protein peak of 36g/L on the electropherogram. Conclusions: This case shows that insolubility of M-proteins in alkaline buffer is one possible cause of false-negative results on capillary zone electrophoresis systems. False-negative results should be considered, especially when accompanying laboratory results are inconsistent with the electropherogra

Oscillatory Activity in the Cortex, Motor Thalamus and Nucleus Reticularis Thalami in Acute TTX and Chronic 6-OHDA Dopamine-Depleted Animals

The motor thalamus (MTh) and the nucleus reticularis thalami (NRT) have been largely neglected in Parkinson's disease (PD) research, despite their key role as interface between basal ganglia (BG) and cortex (Cx). In the present study, we investigated the oscillatory activity within the Cx, MTh, and NRT, in normal and different dopamine (DA)-deficient states. We performed our experiments in both acute and chronic DA-denervated rats by injecting into the medial forebrain bundle (MFB) tetrodotoxin (TTX) or 6-hydroxydopamine (6-OHDA), respectively. Interestingly, almost all the electroencephalogram (EEG) frequency bands changed in acute and/or chronic DA depletion, suggesting alteration of all oscillatory activities and not of a specific band. Overall, δ (2–4 Hz) and θ (4–8 Hz) band decreased in NRT and Cx in acute and chronic state, whilst, α (8–13 Hz) band decreased in acute and chronic states in the MTh and NRT but not in the Cx. The β (13–40 Hz) and γ (60–90 Hz) bands were enhanced in the Cx. In the NRT the β bands decreased, except for high-β (Hβ, 25–30 Hz) that increased in acute state. In the MTh, Lβ and Hβ decreased in acute DA depletion state and γ decreased in both TTX and 6-OHDA-treated animals. These results confirm that abnormal cortical β band are present in the established DA deficiency and it might be considered a hallmark of PD. The abnormal oscillatory activity in frequency interval of other bands, in particular the dampening of low frequencies in thalamic stations, in both states of DA depletion might also underlie PD motor and non-motor symptoms. Our data highlighted the effects of acute depletion of DA and the strict interplay in the oscillatory activity between the MTh and NRT in both acute and chronic stage of DA depletion. Moreover, our findings emphasize early alterations in the NRT, a crucial station for thalamic information processing

Interference during the implicit learning of two different motor sequences

It has been demonstrated that learning a second motor task after having learned a first task may interfere with the long-term consolidation of the first task. However, little is known about immediate changes in the representation of the motor memory in the early acquisition phase within the first minutes of the learning process. Therefore, we investigated such early interference effects with an implicit serial reaction time task in 55 healthy subjects. Each subject performed either a sequence learning task involving two different sequences, or a random control task. The results showed that learning the first sequence led to only a slight, short-lived interference effect in the early acquisition phase of the second sequence. Overall, learning of neither sequence was impaired. Furthermore, the two processes, sequence-unrelated task learning (i.e. general motor training) and the sequence learning itself did not appear to interfere with each other. In conclusion, although the long-term consolidation of a motor memory has been shown to be sensitive to other interfering memories, the present study suggests that the brain is initially able to acquire more than one new motor sequence within a short space of time without significant interferenc

Additivity of the mechanical properties of Al-Sn pseudoalloys

The influence of deformation on the mechanical properties of sintered Al-Sn composites was investigated. It was found that under compression test the strength of investigated materials is an additive value and determined by the rule of mixture. After processing by ECAP the strength of sintered Al-Sn composites increases by more than 2 times but remains additive value. During ECAP, the strengthening of the composites is caused by grinding of the grain structure of the aluminum matrix

Impairment of sleep homeostasis in cervical dystonia patients.

Alterations in brain plasticity seem to play a role in the pathophysiology of cervical dystonia (CD). Since evidences indicate that sleep regulates brain plasticity, we hypothesized that an alteration in sleep homeostatic mechanisms may be involved in the pathogenesis of CD. We explored sleep in control subjects (CTL) and CD patients before (Tpre-BoNT) and after (Tpost-BoNT) botulinum toxin (BoNT) treatment. A physiological slow wave activity (SWA) power decrease throughout the night was observed in CTL but not in CD at Tpre-BoNT. BoNT restored the physiological SWA decrease in CD at Tpost-BoNT. Furthermore, in the first part of the night, CD at Tpost-BNT showed a frontal increase and parietal decrease in SWA power compared to CD at Tpre-BoNT, with a SWA distribution comparable to that observed in CTL. Our data highlighted a pathophysiological relationship between SWA during sleep and CD and provided novel insight into the transient central plastic effect of BoNT

Imagined paralysis reduces motor cortex excitability.

Mental imagery is a powerful capability that engages similar neurophysiological processes that underlie real sensory and motor experiences. Previous studies show that motor cortical excitability can increase during mental imagery of actions. In this study, we focused on possible inhibitory effects of mental imagery on motor functions. We assessed whether imagined arm paralysis modulates motor cortical excitability in healthy participants, as measured by motor evoked potentials (MEPs) of the hand induced by near-threshold transcranial magnetic stimulation (TMS) over the primary motor cortex hand area. We found lower MEP amplitudes during imagined arm paralysis when compared to imagined leg paralysis or baseline stimulation without paralysis imagery. These results show that purely imagined bodily constraints can selectively inhibit basic motor corticospinal functions. The results are discussed in the context of motoric embodiment/disembodiment

Monoclonal gammopathy missed by capillary zone electrophoresis

Serum protein electrophoresis is used as a screening test for monoclonal gammopathies. Here, we present a case of a high-concentration monoclonal immunoglobulin (M-protein) that was missed by serum protein electrophoresis on a Capillarys 2 capillary zone electrophoresis system. The aim of our study was to identify the reason for the failure of the system to detect the M-protein

Cortical slow wave activity correlates with striatal synaptic strength in normal but not in Parkinsonian rats

Urethane-induced cortical slow wave activity (SWA) spreads into the basal ganglia in dopamine (DA)-depleted rat models of Parkinson's disease (PD). During physiological sleep, SWA is powerfully expressed at the beginning of night and progressively reduced during sleep-time reflecting the sleep need. However, its underlying slow oscillations may contribute directly to modulate cortical plasticity. In order to determine the impact of the SWA on synaptic strength and its interplay with DA, we simultaneously recorded the electrocorticogram (ECoG) and the corticocortical- and corticostriatal-evoked potentials (CC-EPs, CS-EPs) during eight hours of robust urethane-induced SWA in both normal and PD animals. A subgroup of PD rats was assessed with repetitive apomorphine (APO) administrations. Normal animals showed a progressive reduction of SWA power during urethane-induced SWA. Compared to normal animals, PD animals showed lower SWA power at the start of anesthesia without a significant reduction over time. Accordingly, synaptic strength measured by CC- and CS-EP amplitudes decreased in normal but not in Parkinsonian rats. The PD animals treated with APO showed a CS-EP amplitude reduction comparable to normal animals. Interestingly, SWA power directly correlated with CS-EP amplitude in normal animals. These data support the hypothesis that cortical SWA is directly associated with the regulation of synaptic efficacy in which DA exerts a crucial role

Amyloid detection and typing yield of skin biopsy in systemic amyloidosis and polyneuropathy.

OBJECTIVE Disease-modifying therapies are available for amyloidosis but are ineffective if end-organ damage is severe. As small fiber neuropathy is an early and common feature of amyloidosis, we assessed detection and typing yield of skin biopsy for amyloid in patients with confirmed systemic amyloidosis and neuropathic symptoms. METHODS In this case-control study, patients with transthyretin and light chain amyloidosis (ATTRv, ATTRwt, and AL) were consecutively recruited. They were sex and age-matched to three control groups (1) non-neuropathic controls (NNC), (2) monoclonal gammopathy of undetermined significance (MGUS), and (3) other neuropathic disease controls (ONC). Patients underwent a double 3 mm skin biopsy in proximal and distal leg. Amyloid index and burden, protein typing by immuno-electron microscopy, intraepidermal nerve fiber density, electroneuromyography, and clinical characteristics were analyzed. RESULTS We studied 15 subjects with confirmed systemic amyloidosis, 20 NNC, 18 MGUS, and 20 ONC. Amyloid was detected in 100% of patients with amyloidosis (87% in ankle and 73% in thigh). It was not detected in any of the control groups. A small fiber neuropathy was encountered in 100% of amyloidosis patients, in 80% of MGUS, and in 78% of ONC. Amyloid burden was higher in ATTRv, followed by AL and ATTRwt. The ultrastructural examination allowed the identification of the precursor protein by immunotyping in most of the cases. INTERPRETATION Skin biopsy is a minimally invasive test with optimal sensitivity for amyloid. It allows amyloid typing by electron microscope to identify the precursor protein. The diagnostic work up of systemic amyloidosis should include a skin biopsy