148 research outputs found
The ontogenesis of action syntax
No full textLanguage and action share similar organizational principles. Both are thought to be hierarchical and recursive in nature. Here we address the relationship between language and action from developmental and neurophysiological perspectives. We discuss three major aspects: The extent of the analogy between language and action; the necessity to extend research on the yet largely neglected aspect of action syntax; the positive contribution of a developmental approach to this topic. We elaborate on the claim that adding an ontogenetic approach will help to obtain a comprehensive picture about both the interplay between language and action and its development, and to answer the question whether the underlying mechanisms of detecting syntactic violations of action sequences are similar to or different from the processing of language syntactic violations
Grasping synergies: A motor-control approach to the mirror neuron mechanism
No full textThe discovery of mirror neurons revived interest in motor theories of perception, fostering a number of new studies as well as controversies. In particular, the degree of motor specificity with which others’ actions are simulated is highly debated. Human corticospinal excitability studies support the conjecture that a mirror mechanism encodes object-directed goals or low-level kinematic features of others’ reaching and grasping actions. These interpretations lead to different experimental predictions and implications for the functional role of the simulation of others’ actions. We propose that the representational granularity of the mirror mechanism cannot be any different from that of the motor system during action execution. Hence, drawing from motor control models, we propose that the building blocks of the mirror mechanism are the relatively few motor synergies explaining the variety of hand functions. The recognition of these synergies, from action observation, can be potentially very robust to visual noise and thus demonstrate a clear advantage of using motor knowledge for classifying others’ action
Motor control may support mirror neuron research with new hypotheses and methods. Reply to comments on "Grasping synergies: A motor-control approach to the mirror neuron mechanism"
No full textElectromagnetic imaging of dielectric targets by using a tomographic systems
No full textThe reconstruction of plastic targets by using an electromagnetic imaging system working at microwave frequencies is considered. A prototype of a tomograph is used to measure field scattered data in a multi-illumination multi-view arrangement. The samples of the field are used to retrieve the two-dimensional distributions of the dielectric parameters of the target under test. Experimental results are provided and the overall reconstruction quality is evaluated
Representing tools as hand movements: Early and somatotopic visuomotor transformations
No full textAbstractThe term affordance defines a property of objects, which relates to the possible interactions that an agent can carry out on that object. In monkeys, canonical neurons encode both the visual and the motor properties of objects with high specificity. However, it is not clear if in humans exists a similarly fine-grained description of these visuomotor transformations. In particular, it has not yet been proven that the processing of visual features related to specific affordances induces both specific and early visuomotor transformations, given that complete specificity has been reported to emerge quite late (300–450ms). In this study, we applied an adaptation-stimulation paradigm to investigate early cortico-spinal facilitation and hand movements׳ synergies evoked by the observation of tools. We adapted, through passive observation of finger movements, neuronal populations coding either for precision or power grip actions. We then presented the picture of one tool affording one of the two grasps types and applied single-pulse Transcranial Magnetic Stimulation (TMS) to the hand primary motor cortex, 150ms after image onset. Cortico-spinal excitability of the Abductor Digiti Minimi and Abductor Pollicis Brevis showed a detailed pattern of modulations, matching tools׳ affordances. Similarly, TMS-induced hand movements showed a pattern of grip-specific whole hand synergies. These results offer a direct proof of the emergence of an early visuomotor transformation when tools are observed, that maintains the same amount of synergistic motor details as the actions we can perform on them
Reconstruction of metallic inclusions inside dielectric targets by means of a microwave tomographic system
No full textExperimental results concerning the inspection at microwave frequencies of wood material with metallic inclusions are reported. They have been obtained by inverting samples of the scattered electromagnetic field collected by a prototype of an imaging system. The system is able to acquire multi-illumination multiview data in a tomographic arrangement. The retrieved maps of the dielectric permittivity and electric conductivity of the cross sections of unknown targets are obtained by applying the distorted-wave Born approximation to the electric field integral equation governing the scattering phenomenon
Imaging of dielectric targets with metallic inclusions by means of a prototype of microwave axial tomograph
No full textMicrowave systems are becoming powerful tools for imaging applications. In fact, when designed by taking into account the full scattering phenomena, they are able to directly provide information about the physical properties of the target under test. In this paper, the possibility of detecting metallic inclusions inside dielectric objects is assessed by using a prototype of a microwave axial tomograph, which is able to create images of the dielectric permittivity and of the electric conductivity of the inspected target
Spasmolytic Effects of Aphanizomenon Flos Aquae (AFA) Extract on the Human Colon Contractility.
No full textThe blue-green algae Aphanizomenon flos aquae (AFA), rich in beneficial nutrients, exerts
various beneficial effects, acting in different organs including the gut. Klamin® is an AFA extract
particularly rich in -PEA, a trace-amine considered a neuromodulator in the central nervous
system. To date, it is not clear if -PEA exerts a role in the enteric nervous system. The aims of
the present study were to investigate the effects induced by Klamin® on the human distal colon
mechanical activity, to analyze the mechanism of action, and to verify a -PEA involvement. The
organ bath technique, RT-PCR, and immunohistochemistry (IHC) were used. Klamin® reduced, in a
concentration-dependent manner, the amplitude of the spontaneous contractions. EPPTB, a traceamine
receptor (TAAR1) antagonist, significantly antagonized the inhibitory effects of both Klamin®
and exogenous -PEA, suggesting a trace-amine involvement in the Klamin® effects. Accordingly,
AphaMax®, an AFA extract containing lesser amount of -PEA, failed to modify colon contractility.
Moreover, the Klamin® effects were abolished by tetrodotoxin, a neural blocker, but not by L-NAME,
a nitric oxide-synthase inhibitor. On the contrary methysergide, a serotonin receptor antagonist,
significantly antagonized the Klamin® effects, as well as the contractility reduction induced by 5-HT.
The RT-PCR analysis revealed TAAR1 gene expression in the colon and the IHC experiments showed
that 5-HT-positive neurons are co-expressed with TAAR1 positive neurons. In conclusion, the results
of this study suggest that Klamin® exerts spasmolytic effects in human colon contractility through
-PEA, that, by activating neural TAAR1, induce serotonin release from serotoninergic neurons of
the myenteric plexus
A multistatic tomographic approach to microwave imaging of dielectric targets
No full textIn the last years, the development of microwave imaging systems, aimed at reconstructing images of the dielectric properties of unknown targets from measures of the scattered field, has been a continuously pursued target. There are mainly two topics that must be faced. First of all, it is necessary to create fast and efficient measurement setups for obtaining the samples of the scattered electric field. Secondly, it is necessary to develop numerical methods able to extract from such measured values the needed information. In this paper, a multistatic measurement setup and an efficient reconstruction procedure are presented. Experimental results are provided in order to demonstrate the effectiveness of the proposed system
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