Asymmetry of parietal interhemispheric connections in humans

Visuospatial abilities are preferentially mediated by the right hemisphere. Although this asymmetry of function is thought to be due to an unbalanced interaction between cerebral hemispheres, the underlying neurophysiological substrate is still largely unknown. Here, using a method of trifocal transcranial magnetic stimulation, we show that the right, but not left, human posterior parietal cortex exerts a strong inhibitory activity over the contralateral homologous area by a short-latency connection. We also clarify, using diffusion-tensor magnetic resonance imaging, that such an interaction is mediated by direct transcallosal projections located in the posterior corpus callosum. We argue that this anatomo-functional network may represent a possible neurophysiological basis for the ongoing functional asymmetry between parietal cortices, and that its damage could contribute to the clinical manifestations of neglect

Reversal of TMS-induced motor twitch by training is associated with a reduction in excitability of the antagonist muscle

Background: A single session of isolated repetitive movements of the thumb can alter the response to transcranial magnetic stimulation (TMS), such that the related muscle twitch measured post-training occurs in the trained direction. This response is attributed to transient excitability changes in primary motor cortex (M1) that form the early part of learning. We investigated; (1) whether this phenomenon might occur for movements at the wrist, and (2) how specific TMS activation patterns of opposing muscles underlie the practice-induced change in direction. Methods: We used single-pulse suprathreshold TMS over the M1 forearm area, to evoke wrist movements in 20 healthy subjects. We measured the preferential direction of the TMS-induced twitch in both the sagittal and coronal plane using an optical goniometer fixed to the dorsum of the wrist, and recorded electromyographic (EMG) activity from the flexor carpi radialis (FCR) and extensor carpi radialis (ECR) muscles. Subjects performed gentle voluntary movements, in the direction opposite to the initial twitch for 5 minutes at 0.2 Hz. We collected motor evoked potentials (MEPs) elicited by TMS at baseline and for 10 minutes after training. Results: Repetitive motor training was sufficient for TMS to evoke movements in the practiced direction opposite to the original twitch. For most subjects the effect of the newly-acquired direction was retained for at least 10 minutes before reverting to the original. Importantly, the direction change of the movement was associated with a significant decrease in MEP amplitude of the antagonist to the trained muscle, rather than an increase in MEP amplitude of the trained muscle. Conclusions: These results demonstrate for the first time that a TMS-twitch direction change following a simple practice paradigm may result from reduced corticospinal drive to muscles antagonizing the trained direction. Such findings may have implications for training paradigms in neurorehabilitation

Biodegradazione della bagassa di guayule con "White-Rot Fungi" finalizzata alla produzione di zuccheri di 2° generazione per il progetto "ALBE"

The biodegradation pretreatment of guayule bagasse by White Rot Fungi (WRF) using two lignin-lytic strains belonging to the Pleurotus ostreatus and Fomitiporia mediterranea species (Basidiomycotina) was studied under in vitro conditions for assessing the released 2nd-generation fermentable sugars suitable for producing bio-elastomers into “ALBE” Project (partnership among ENEA and VERSALIS). Guayule bagasse is an important and recalcitrant lignin-cellulosic co-product obtained from guayule crop, an alternative plant to caucciù tree for the industrial production of rubber, after industrial extraction of rubber and resin. In this research work were: 1) selected two strains of Pleurotus ostreatus and Fomitiporia mediterranea provided by the collection of University of Bari under laboratory condition on the basis of their growth performances; 2) analyzed guayule bagasse samples after resin extraction; 3) optimized the parameters of the biodegradation process by using liquid cultures under rotary shaking; 4) performed the releasing of fermentable sugars from guayule bagasse. The determination of glucose and other minor secondary metabolites were carried out by analytical standard methods after hydrolysis enzymatic of the crude cultural filtrates of each fungus. The results showed that the released sugars from guayule bagasse by biodegradation with WRF was significantly increased if compared to control, nevertheless more researches of this topic are needed.In questo lavoro, svolto nell’ambito del Progetto di Ricerca ENEA-VERSALIS “ALBE”, sono descritti la metodologia sperimentale e i risultati ottenuti su un processo di pretrattamento microbiologico della bagassa di guayule. Il guayule è una coltura alternativa al caucciù (albero della gomma) e può essere utilizzata per la produzione industriale di gomma naturale. Il residuo derivato (bagassa) è un materiale lignocellulosico che può essere valorizzato per la produzione di zuccheri di 2° generazione. In particolare il glucosio può essere utilizzato per la produzione di butandiolo, un building block, per ottenere elastomeri, obiettivo finale del progetto in esame. Nel merito di questo rapporto, il residuo lignocellulosico del guayule è stato caratterizzato e sottoposto ad un pretrattamento microbiologico con l’impiego di due ceppi di funghi Basidiomiceti ligninolitici, agenti della “carie bianca del legno” del tipo “WRF” e appartenenti alle specie Pleurotus ostreatus e Fomitiporia mediterranea. Essi sono stati selezionati in laboratorio per le loro prestazioni di crescita e utilizzati per pretrattare la bagassa di guayule. Dopo il pretrattamento è stata eseguita l’idrolisi enzimatica della cellulosa per l’ottenimento di un brodo zuccherino e di un residuo insolubile a base ligninica. Lo studio ha previsto sia una fase preliminare di ottimizzazione, consistita nel variare la durata del pretrattamento biologico (4-12 giorni) ed il dosaggio enzimatico, sia l’esecuzione di prove rappresentative su idonei quantitativi di bagassa con lo scopo di valutare i rendimenti in zuccheri fermentabili e i relativi flussi di massa. I risultati ottenuti, anche se richiedono un ulteriore approfondimento, hanno permesso di ottenere una preliminare valutazione dell’efficacia di questo tipo di pretrattamento, che ha riguardato una biomassa residuale particolarmente recalcitrante, come la bagassa del guayule, per la produzione di zuccheri di 2° generazione. Le attività sono state svolte in collaborazione con l’Università di Bari

Engineering Dion-Jacobson Perovskites in Polariton Waveguides

Hybrid two-dimensional perovskites hold considerable promise as semiconductors for a wide range of optoelectronic applications. Many efforts are addressed to exploit the potential of these materials by tailoring their characteristics. In this work, the optical properties and electronic band structure in three new Dion-Jacobson (DJ) perovskites (PVKs) are engineered by modulating their structural distortion. Two different interlayer cations: 1-6, Hexamethylendiammonium, HE, and 3-(Dimethylamino)-1-propylammonium, DMPA, have been selected to investigate the role of the cation length and the ammonium binding group on the crystalline structure. This study provides new insights into the understanding of the structure-property relationship in DJ perovskites and demonstrates that exciton characteristics can be easily modulated with the judicious design of the organic cations. DJ PVKs developed in this work were also grown as size-controlled single crystal microwires through a microfluidic-assisted synthesis technique and integrated in a nanophotonic device. The DJ PVK microwire acts as a waveguide exhibiting strong light-matter coupling between the crystal optical modes and DJ PVK exciton. Through the investigation of these polariton waveguides, the nature of the double peak emission, which is often observed in these materials and whose nature is largely debated in the literature, is demonstrated originating from the hybrid polariton state

FMRI resting slow fluctuations correlate with the activity of fast cortico-cortical physiological connections

Recording of slow spontaneous fluctuations at rest using functional magnetic resonance imaging (fMRI) allows distinct long-range cortical networks to be identified. The neuronal basis of connectivity as assessed by resting-state fMRI still needs to be fully clarified, considering that these signals are an indirect measure of neuronal activity, reflecting slow local variations in de-oxyhaemoglobin concentration. Here, we combined fMRI with multifocal transcranial magnetic stimulation (TMS), a technique that allows the investigation of the causal neurophysiological interactions occurring in specific cortico-cortical connections. We investigated whether the physiological properties of parieto-frontal circuits mapped with short-latency multifocal TMS at rest may have some relationship with the resting-state fMRI measures of specific resting-state functional networks (RSNs). Results showed that the activity of fast cortico-cortical physiological interactions occurring in the millisecond range correlated selectively with the coupling of fMRI slow oscillations within the same cortical areas that form part of the dorsal attention network, i.e., the attention system believed to be involved in reorientation of attention. We conclude that resting-state fMRI ongoing slow fluctuations likely reflect the interaction of underlying physiological cortico-cortical connections

Lignocellulosic biomass as carbon source by steam explosion pretreatment

n/

Genetic heterogeneity at the glucose-6-phosphate dehydrogenase locus in southern Italy: a study on a population from the Matera district.

Glucose-6-phosphate dehydrogenase (G6PD) has been analyzed by gel electrophoresis and by quantitative assay in an unselected sample of 1524 schoolboys from the province of Matera (Lucania) in southern Italy. We have identified 43 subjects with a G6PD variant. Of these, 31 had severe G6PD deficiency, nine had mild to moderate deficiency, and three had a non-deficient electrophoretic variant. The overall rate of G6PD deficiency was 2.6%. The frequency of G6PD deficiency, ranging from 7.2% on the Ionian Coast to zero on the eastern side of the Lucanian Apennines, appears to be inversely related to the distance of each town examined from the Ionian Coast, suggesting that this geographic distribution may reflect, at least in part, gene flow from Greek settlers. Biochemical characterization has shown that most of the G6PD deficiency in this population is accounted for by G6PD Mediterranean. In addition, we have found several examples of two other known polymorphic variants (G6PD Cagliari and G6PD A-); three new polymorphic variants, G6PD Metaponto (class III), G6PD Montalbano (class III), and G6PD Pisticci (class IV); and two sporadic variants, G6PD Tursi (class III) and G6PD Ferrandina (class II). These data provide further evidence for the marked genetic heterogeneity of G6PD deficiency within a relatively narrow geographic area and they prove the presence in the Italian peninsula of a gene (GdA-) regarded as characteristically African

Dopaminergic modulation of cortical plasticity in Alzheimer's disease patients

In animal models of Alzheimer's disease (AD), mechanisms of cortical plasticity such as long-term potentiation (LTP) and long-term depression (LTD) are impaired. In AD patients, LTP-like cortical plasticity is abolished, whereas LTD seems to be preserved. Dopaminergic transmission has been hypothesized as a new player in ruling mechanisms of cortical plasticity in AD. We aimed at investigating whether administration of the dopamine agonist rotigotine (RTG) could modulate cortical plasticity in AD patients, as measured by theta burst stimulation (TBS) protocols of repetitive transcranial stimulation applied over the primary motor cortex. Thirty mild AD patients were tested in three different groups before and after 4 weeks of treatment with RTG, rivastigmine (RVT), or placebo (PLC). Each patient was evaluated for plasticity induction of LTP/LTD-like effects using respectively intermittent TBS (iTBS) or continuous TBS protocols. Short-latency afferent inhibition (SAI) protocol was performed to indirectly assess central cholinergic activity. A group of age-matched healthy controls was recruited for baseline comparisons. Results showed that at baseline, AD patients were characterized by impaired LTP-like cortical plasticity, as assessed by iTBS. These reduced levels of LTP-like cortical plasticity were increased and normalized after RTG administration. No effect was induced by RVT or PLC on LTP. LTD-like cortical plasticity was not modulated in any condition. Cholinergic activity was increased by both RTG and RVT. Our findings reveal that dopamine agonists may restore the altered mechanisms of LTP-like cortical plasticity in AD patients, thus providing novel implications for therapies based on dopaminergic stimulation