Modulation of the activity of the locomotor central pattern generator in the rat spinal cord in vitro

The present study has investigated the rhythmic properties of spinal networks in the neonatal rat spinal cord in vitro, by means of intracellular recordings from single motoneurons (MNs) and extracellular recordings from ventral and dorsal roots (VRs;DRs). Distinct subclasses of metabotropic glutamate receptors (mGluRs) on rat spinal neurons mediated complex facilitatory and inhibitory effects. The class I agonist DHPG evoked MN depolarization (via the mGluR1 subtype) mostly at network level and generated sustained, network-dependent oscillations (via the mGluR5 subtype). DHPG also decreased the amplitude of reflex responses induced by DR stimuli, an effect unrelated to depolarization but dependent on glycinergic transmission. Single reflex responses were insensitive to group I mGluRs antagonists, suggesting no phasic activation of group I receptors during this process. Finally, DHPG depressed the glycinergic recurrent IPSP, perhaps by impairing the cholinergic input to Renshaw cells. Thus, the cellular distribution of those mGluRs at strategic circuit connections may determine the functional outcome of the network in terms of excitation or inhibition. Activation of class II or III mGluRs had no direct action on MNs although it strongly blocked evoked synaptic transmission, presumably acting at presynaptic level. To extend our understanding of the network-based properties, which enable a neuronal circuit to produce sustained electrical oscillations, we explored the potential contribution of mGluRs to generate rhythmic discharges. During cumulative depolarization or fictive locomotion, spinal mGluRs were minimally activated by endogenous glutamate, although they could potently modulate these responses once activated by exogenously applied mGluR agonists. Disinhibited bursting was associated with the activation of mGluR1 receptors (facilitating network excitability) and of group II mGluRs (depressing it). We investigated if the K+ channel blocker 4-aminopyridine (4-AP) could facilitate spinal locomotor networks in addition to its well-known effect on motor nerve conduction. 4-AP produced synchronous VR oscillations, which did not develop into fictive locomotion. These oscillations had network origin, required intact glutamatergic transmission and were probably amplified via electrotonic coupling. 4-AP slightly increased input resistance of lumbar MNs, without affecting their action or resting potentials. DR evoked synaptic responses were enhanced by 4-AP without changes in axon conduction. 4-AP accelerated chemically or electrically induced fictive locomotion and facilitated the onset of fictive locomotion in the presence of subthreshold stimuli, that were previously insufficient to activate locomotor patterns. Thus, although 4-AP per se could not directly activate the locomotor network of the spinal cord, it could strongly facilitate the locomotor program initiated by neurochemicals or electrical stimuli. On DRs, 4-AP induced sustained synchronous oscillations smaller than electrically evoked synaptic potentials, persistent after sectioning off the ventral region and preserved in an isolated dorsal quadrant, indicating their dorsal horn origin. 4-AP oscillations were network mediated via glutamatergic, glycinergic and GABAergic transmission. Isolated ventral horn areas could not generate 4-AP oscillations, although their intrinsic, disinhibited bursting was accelerated by the substance. Activation of fictive locomotion by either application of neurochmicals or stimulus trains to a single DR reversibly suppressed DR oscillations induced by 4-AP. The present electrophysiological investigation also examined whether the broad spectrum potassium channel blocker tetraethylammonium (TEA) could generate locomotor-like patterns. Low concentrations of TEA induced irregular, synchronous discharges incompatible with locomotion. Higher concentrations evoked alternating discharges between flexor and extensor motor pools, plus a large depolarization of MNs with spike broadening. The alternating discharges were superimposed on slow, shallow waves of synchronous depolarization. Rhythmic alternating patterns were suppressed by blockers of glutamate, GABAA and glycine receptors, disclosing a background of depolarizing bursts inhibited by antagonism of group I mGluRs. Furthermore, TEA also evoked irregular discharges on DRs. The rhythmic alternating patterns elicited by TEA on VRs were relatively stereotypic, had limited synergy with the fictive locomotion induced by DR stimuli, and were not accelerated by 4-AP. Horizontal section of the spinal cord preserved irregular VR discharges and DR discharges, demonstrating that the action of TEA on spinal networks was fundamentally different from that of 4-AP

Understanding Etruscan art and architecture through 3D modeling: the case of Volterra

Nowadays, archaeology and modern 3D modelling and representation technologies form an unbreakable bond, considered essential and indispensable by many experts and scholars. Although with different goals and purposes, new hardware and software available and specially designed web platforms allow the archaeologist adequately trained to create, visualize, analyze, and share 3D data derived from computer graphics or from image- and range-based acquisition procedures. Currently, a very important topic is the relationship between user and 3D model: from the simple passive fruition, we are moving increasingly towards a real interaction within immersive virtual environments. In this sense, the contribution of the archaeologist is critical to determine what to display and what to interact with, according to the end user and his skills and knowledge. In fact, the following case studies related to sites, monuments and artefacts of the Etruscan town of Volterra represent the evolution of this interaction/relationship, helping to make the fruition of archaeological evidence, that at present is still difficult to access and understanding, easier and more interesting

Understanding Etruscan Art and Architecture through 3D modeling: the case of Volterra

Archaeology and modern 3D modelling and representation technologies form an unbreakable bond, considered essential and indispensable by many experts and scholars. Although with different goals and purposes, new hardware and software available and specially designed web platforms allow the archaeologist adequately trained to create, visualize, analyze, and share 3D data derived from computer graphics or from image- and range-based acquisition procedures. Currently, a very important topic is the relationship between user and 3D model: from the simple passive fruition, we are moving increasingly towards a real interaction within immersive virtual environments. In this sense, the contribution of the archaeologist is critical to determine what to display and what to interact with, according to the end user and his skills and knowledge. In fact, the following case studies related to sites, monuments and artefacts of the Etruscan town of Volterra represent the evolution of this interaction/relationship, helping to make the fruition of archaeological evidence, that at present is still difficult to access and understanding, easier and more interesting

Afferent Input Induced by Rhythmic Limb Movement Modulates Spinal Neuronal Circuits in an Innovative Robotic In Vitro Preparation

Locomotor patterns are mainly modulated by afferent feedback, but its actual contribution to spinal network activity during continuous passive limb training is still unexplored. To unveil this issue, we devised a robotic in vitro setup (Bipedal Induced Kinetic Exercise, BIKE) to induce passive pedaling, while simultaneously recording low-noise ventral and dorsal root (VR and DR) potentials in isolated neonatal rat spinal cords with hindlimbs attached. As a result, BIKE evoked rhythmic afferent volleys from DRs, reminiscent of pedaling speed. During BIKE, spontaneous VR activity remained unchanged, while a DR rhythmic component paired the pedaling pace. Moreover, BIKE onset rarely elicited brief episodes of fictive locomotion (FL) and, when trains of electrical pulses were simultaneously applied to a DR, it increased the amplitude, but not the number, of FL cycles. When BIKE was switched off after a 30-min training, the number of electrically induced FL oscillations was transitorily facilitated, without affecting VR reflexes or DR potentials. However, 90 min of BIKE no longer facilitated FL, but strongly depressed area of VR reflexes and stably increased antidromic DR discharges. Patch clamp recordings from single motoneurons after 90-min sessions indicated an increased frequency of both fast- and slow-decaying synaptic input to motoneurons. In conclusion, hindlimb rhythmic and alternated pedaling for different durations affects distinct dorsal and ventral spinal networks by modulating excitatory and inhibitory input to motoneurons. These results suggest defining new parameters for effective neurorehabilitation that better exploits spinal circuit activity

The sanctuary of Punta Stilo at Kaulonia-Monasterace (Rc, Italy): preliminary results of the close range photogrammetric surveys 2012-2013

During the 2012–2013 excavations at the Sanctuary of Punta Stilo at Kaulonia, carried out by the University of Pisa and the Scuola Normale Superiore of Pisa, close range aerial and terrestrial photogrammetric surveys were tested for the first time. The aim of the test was to verify the accuracy of the site planimetry currently used, dating back also to a century ago. The 3D data obtained have allowed new data to be acquired for correcting and updating the mapping of the site

Rat locomotor spinal circuits in vitro are activated by electrical stimulation with noisy waveforms sampled from human gait

Noisy waveforms, sampled from an episode of fictive locomotion (FL) and delivered to a dorsal root (DR), are a novel electrical stimulating protocol demonstrated as the most effective for generating the locomotor rhythm in the rat isolated spinal cord. The present study explored if stimulating protocols constructed by sampling real human locomotion could be equally efficient to activate these locomotor networks in vitro. This approach may extend the range of usable stimulation protocols and provide a wide palette of noisy waveforms for this purpose. To this end, recorded electromyogram (EMG) from leg muscles of walking adult volunteers provided a protocol named ReaListim (Real Locomotion-induced stimulation) that applied to a single DR successfully activated FL. The smoothed kinematic profile of the same gait failed to do so like nonphasic noisy patterns derived from standing and isometric contraction. Power spectrum analysis showed distinctive low-frequency domains in ReaListim, along with the high-frequency background noise. The current study indicates that limb EMG signals (recorded during human locomotion) applied to DR of the rat spinal cord are more effective than EMG traces taken during standing or isometric contraction of the same muscles to activate locomotor networks. Finally, EMGs recorded during various human motor tasks demonstrated that noisy waves of the same periodicity as ReaListim, could efficiently activate the in vitro central pattern generator (CPG), regardless of the motor task from which they had been sampled. These data outline new strategies to optimize functional stimulation of spinal networks after injury

Commento di Sebastiano Taccola a Un’età contro la storia. Saggio sulla rivoluzione del XXI secolo

«Da cosa è possibile dedurre la natura coerente, sistematica e dialettica del tempo storico? Da quali aspetti inferire lo status dialettico del tempo storico, senza che questo venga naturalizzato e assunto come legge di natura?». Sebastiano Taccola nel suo commento al saggio di Giuseppe Carlo Marino su globalizzazione e crisi del “pensare storico” pone queste domande offrendoci importanti spunti di lettura del mutamento e degli sviluppi delle relazioni tra pensiero dell’uomo e significato della storia.«Where can we possible deduce the coherent systematic dialectical nature, of the historical time from? what aspects can we infer the dialectical status of the historical time, without which it could be normalized and assumed as a nature law from?». In his comment to Giuseppe Carlo Marino’s essay about the globalization and crisis of “historical thought”, Sebastiano Taccola asks these questions by giving us important starting points of the changes and developments of the relationships between men thought and sense of history

Zinc oxide nanoparticles as selective killers of proliferating cells

Background: It has recently been demonstrated that zinc oxide nanoparticles (ZnO NPs) induce death of cancerous cells whilst having no cytotoxic effect on normal cells. However, there are several issues which need to be resolved before translation of zinc oxide nanoparticles into medical use, including lack of suitable biocompatible dispersion protocols and a better understanding being needed of the mechanism of their selective cytotoxic action. Methods: Nanoparticle dose affecting cell viability was evaluated in a model of proliferating cells both experimentally and mathematically. The key issue of selective toxicity of ZnO NPs toward proliferating cells was addressed by experiments using a biological model of noncancerous cells, ie, mesenchymal stem cells before and after cell differentiation to the osteogenic lineage. Results: In this paper, we report a biocompatible protocol for preparation of stable aqueous solutions of monodispersed zinc oxide nanoparticles. We found that the threshold of intracellular ZnO NP concentration required to induce cell death in proliferating cells is 0.4 ± 0.02 mM. Finally, flow cytometry analysis revealed that the threshold dose of zinc oxide nanoparticles was lethal to proliferating pluripotent mesenchymal stem cells but exhibited negligible cytotoxic effects to osteogenically differentiated mesenchymal stem cells. Conclusion: Results confirm the ZnO NP selective cytotoxic action on rapidly proliferating cells, whether benign or malignant