Numbers in Action

Humans show a remarkable tendency to describe and think of numbers as being placed on a mental number line (MNL), with smaller numbers located on the left and larger ones on the right. Faster responses to small numbers are indeed performed on the left side of space, while responses to large numbers are facilitated on the right side of space (spatial-numerical association of response codes, SNARC effect). This phenomenon is considered the experimental demonstration of the MNL and has been extensively replicated throughout a variety of paradigms. Nevertheless, the majority of previous literature has mainly investigated this effect by means of response times and accuracy, whereas studies considering more subtle and automatic measures such as kinematic parameters are rare (e.g., in a reaching-to-grasp movement, the grip aperture is enlarged in responding to larger numbers than in responding to small numbers). In this brief review we suggest that numerical magnitude can also affect the what and how of action execution (i.e., temporal and spatial components of movement). This evidence could have large implications in the strongly debated issue concerning the effect of experience and culture on the orientation of MNL.

High serum uric acid levels increase the risk of metabolic syndrome in elderly women: The PRO.V.A study

BACKGROUND AND AIMS

Serum uric acid (SUA) is the end-product of purine metabolism in humans, and its levels often increase in subjects with metabolic syndrome (MetS). Despite several studies demonstrating a relationship between increased SUA levels and the prevalence of MetS, prospective data on SUA as a predictor of the incidence of MetS in the elderly are limited. Our aim was to conduct a prospective study on the association between SUA concentrations and the onset of MetS in an elderly Italian cohort.

METHODS AND RESULTS

This is a cohort study (Progetto Veneto Anziani; Pro.V.A.) involving community-dwelling subjects aged ≥65 years and followed up for a mean 4.4 years. We included 1128 participants (aged 74.7 ± 7.1 years) without MetS at the baseline. Gender-specific SUA groups according to the standard deviation (SD) from the mean were considered, taking the incidence of MetS as the main outcome. The mean SUA level was significantly higher in men than in women (5.4 ± 1.2 vs. 4.5 ± 1.2 mg/dl; p < 0.0001). Over the 4.4-year follow-up, 496 individuals developed MetS. After adjusting for potential confounders, Cox's regression analysis revealed no relationship between higher baseline SUA concentrations and the incidence of MetS in men or in the sample as whole, while women with SUA levels more than 1 SD above the mean (≥5.7 mg/dl) carried a 58% higher risk (95%CI: 1.03-2.40; p = 0.03) of being newly diagnosed with MetS during the follow-up.

CONCLUSION

High SUA levels significantly and independently predicted MetS in older women, but not in men, over a 4.4-year follow-up.

Kick with the finger: symbolic actions shape motor cortex excitability

A large body of research indicates that observing actions made by others is associated with corresponding motor facilitation of the observer's corticospinal system. However, it is still controversial whether this matching mechanism strictly reflects the kinematics of the observed action or its meaning. To test this issue, motor evoked potentials induced by single-pulse transcranial magnetic stimulation were recorded from hand and leg muscles while participants observed a symbolic action carried out with the index finger, but classically performed with the leg (i.e., a soccer penalty kick). A control condition in which participants observed a similar (but not symbolic) hand movement was also included. Results showed that motor facilitation occurs both in the observer's hand (first dorsal interosseous) and leg (quadriceps femoris) muscles. The present study provides evidence that both the kinematics and the symbolic value of an observed action are able to modulate motor cortex excitability. The human motor system is thus not only involved in mirroring observed actions but is also finely tuned to their symbolic value.

A kinematic study on (un)intentional imitation in bottlenose dolphins

The aim of the present study was to investigate the effect of observing other's movements on subsequent performance in bottlenose dolphins. The imitative ability of non-human animals has intrigued a number of researchers. So far, however, studies in dolphins have been confined to intentional imitation concerned with the explicit request to imitate other agents. In the absence of instruction to imitate, do dolphins (un)intentionally replicate other's movement features? To test this, dolphins were filmed while reaching and touching a stimulus before and after observing another dolphin (i.e., model) performing the same action. All videos were reviewed and segmented in order to extract the relevant movements. A marker was inserted post hoc via software on the videos upon the anatomical landmark of interest (i.e., rostrum) and was tracked throughout the time course of the movement sequence. The movement was analyzed using an in-house software developed to perform two-dimensional (2D) post hoc kinematic analysis. The results indicate that dolphins' kinematics is sensitive to other's movement features. Movements performed for the "visuomotor priming" condition were characterized by a kinematic pattern similar to that performed by the observed dolphin (i.e., model). Addressing the issue of spontaneous imitation in bottlenose dolphins might allow ascertaining whether the potential or impulse to produce an imitative action is generated, not just when they intend to imitate, but whenever they watch another conspecific's behavior. In closing, this will clarify whether motor representational capacity is a by-product of factors specific to humans or whether more general characteristics such as processes of associative learning prompted by high level of encephalization could help to explain the evolution of this ability.

Intersegmental Coordination in the Kinematics of Prehension Movements of Macaques

The most popular model to explain how prehensile movements are organized assumes that they comprise two "components", the reaching component encoding information regarding the object's spatial location and the grasping component encoding information on the object's intrinsic properties such as size and shape. Comparative kinematic studies on grasping behavior in the humans and in macaques have been carried out to investigate the similarities and differences existing across the two species. Although these studies seem to favor the hypothesis that macaques and humans share a number of kinematic features it remains unclear how the reaching and grasping components are coordinated during prehension movements in free-ranging macaque monkeys. Twelve hours of video footage was filmed of the monkeys as they snatched food items from one another (i.e., snatching) or collect them in the absence of competitors (i.e., unconstrained). The video samples were analyzed frame-by-frame using digitization techniques developed to perform two-dimensional post-hoc kinematic analyses of the two types of actions. The results indicate that only for the snatching condition when the reaching variability increased there was an increase in the amplitude of maximum grip aperture. Besides, the start of a break-point along the deceleration phase of the velocity profile correlated with the time at which maximum grip aperture occurred. These findings suggest that macaques can spatially and temporally couple the reaching and the grasping components when there is pressure to act quickly. They offer a substantial contribution to the debate about the nature of how prehensile actions are programmed.

Congruent and Incongruent Corticospinal Activations at the Level of Multiple Effectors

Motor resonance is defined as the subliminal activation of the motor system while observing actions performed by others. However, resonating with another person's actions is not always an appropriate response: In real life, people do not just imitate but rather respond in a suitable fashion. A growing body of neurophysiologic studies has demonstrated that motor resonance can be overridden by complementary motor responses (such as preparing a precision grip on a small object when seeing an open hand in sign of request). In this study, we investigated the relationship between congruent and incongruent corticospinal activations at the level of multiple effectors. The modulation of motor evoked potentials evoked by single-pulse TMS over the motor cortex was assessed in upper and lower limb muscles of participants observing a soccer player performing a penalty kick straight in their direction. Study results revealed a double dissociation: Seeing the soccer player kicking the ball triggered a motor resonance in the observer's lower limb, whereas the upper limb response afforded by the object was overridden. On the other hand, seeing the ball approaching the observers elicited a complementary motor activation in upper limbs while motor resonance in lower limbs disappeared. Control conditions showing lateral kicks, mimicked kicks, and a ball in penalty area were also included to test the motor coding of object affordances. Results point to a modulation of motor responses in different limbs over the course of action and in function of their relevance in different contexts. We contend that ecologically valid paradigms are now needed to shed light on the motor system functioning in complex forms of interaction.

Motor interference in interactive contexts

Action observation and execution share overlapping neural substrates, so that simultaneous activation by observation and execution modulates motor performance. Previous literature on simple prehension tasks has revealed that motor influence can be two-sided: facilitation for observed and performed congruent actions and interference for incongruent actions. But little is known of the specific modulations of motor performance in complex forms of interaction. Is it possible that the very same observed movement can lead either to interference or facilitation effects on a temporally overlapping congruent executed action, depending on the context? To answer this question participants were asked to perform a reach-to-grasp movement adopting a precision grip (PG) while: (i) observing a fixation cross, (ii) observing an actor performing a PG with interactive purposes, (iii) observing an actor performing a PG without interactive purposes. In particular, in the interactive condition the actor was shown trying to pour some sugar on a large cup located out of her reach but close to the participant watching the video, thus eliciting in reaction a complementary whole-hand grasp. Notably, fine-grained kinematic analysis for this condition revealed a specific delay in the grasping and reaching components and an increased trajectory deviation despite the observed and executed movement’s congruency. Moreover, early peaks of trajectory deviation seem to indicate that socially relevant stimuli are acknowledged by the motor system very early. These data suggest that interactive contexts can determine a prompt modulation of stimulus–response compatibility effects.

Complementary actions

Complementary colors are color pairs which, when combined in the right proportions, produce white or black. Complementary actions refer here to forms of social interaction wherein individuals adapt their joint actions according to a common aim. Notably, complementary actions are incongruent actions. But being incongruent is not sufficient to be complementary (i.e., to complete the action of another person). Successful complementary interactions are founded on the abilities: (i) to simulate another person's movements, (ii) to predict another person's future action/s, (iii) to produce an appropriate incongruent response which differ, while interacting, with observed ones, and (iv) to complete the social interaction by integrating the predicted effects of one's own action with those of another person. This definition clearly alludes to the functional importance of complementary actions in the perception-action cycle and prompts us to scrutinize what is taking place behind the scenes. Preliminary data on this topic have been provided by recent cutting-edge studies utilizing different research methods. This mini-review aims to provide an up-to-date overview of the processes and the specific activations underlying complementary actions.

Exploring manual asymmetries during grasping: a dynamic causal modeling approach

Recording of neural activity during grasping actions in macaques showed that grasp-related sensorimotor transformations are accomplished in a circuit constituted by the anterior part of the intraparietal sulcus (AIP), the ventral (F5) and the dorsal (F2) region of the premotor area. In humans, neuroimaging studies have revealed the existence of a similar circuit, involving the putative homolog of macaque areas AIP, F5, and F2. These studies have mainly considered grasping movements performed with the right dominant hand and only a few studies have measured brain activity associated with a movement performed with the left non-dominant hand. As a consequence of this gap, how the brain controls for grasping movement performed with the dominant and the non-dominant hand still represents an open question. A functional magnetic resonance imaging (fMRI) experiment has been conducted, and effective connectivity (dynamic causal modeling, DCM) was used to assess how connectivity among grasping-related areas is modulated by hand (i.e., left and right) during the execution of grasping movements toward a small object requiring precision grasping. Results underlined boosted inter-hemispheric couplings between dorsal premotor cortices during the execution of movements performed with the left rather than the right dominant hand. More specifically, they suggest that the dorsal premotor cortices may play a fundamental role in monitoring the configuration of fingers when grasping movements are performed by either the right and the left hand. This role becomes particularly evident when the hand less-skilled (i.e., the left hand) to perform such action is utilized. The results are discussed in light of recent theories put forward to explain how parieto-frontal connectivity is modulated by the execution of prehensile movements.

The left side of motor resonance

Motor resonance is defined as the internal activation of an observer's motor system, specifically attuned to the perceived movement. In social contexts, however, different patterns of observed and executed muscular activation are frequently required. This is the case, for instance, of seeing a key offered with a precision grip and received by opening the hand. Novel evidence suggests that compatibility effects in motor resonance can be altered by social response preparation. What is not known is how handedness modulates this effect. The present study aimed at determining how a left- and a right-handed actor grasping an object and then asking for a complementary response influences corticospinal activation in left- and right-handers instructed to observe the scene. Transcranial magnetic stimulation (TMS)-induced motor evoked potentials (MEPs) were thus recorded from the dominant hands of left- and right-handers. Interestingly, requests posed by the right-handed actor induced a motor activation in the participants' respective dominant hands, suggesting that left-handers tend to mirror right-handers with their most efficient hand. Whereas requests posed by the left-handed actor activated the anatomically corresponding muscles (i.e., left hand) in all the participants, right-handers included. Motor resonance effects classically reported in the literature were confirmed when observing simple grasping actions performed by the right-handed actor. These findings indicate that handedness influences both congruent motor resonance and complementary motor preparation to observed actions.

An investigation of the neural circuits underlying reaching and reach-to-grasp movements: from planning to execution

Experimental evidence suggests the existence of a sophisticated brain circuit specifically dedicated to reach-to-grasp planning and execution, both in human and non-human primates (Castiello, 2005). Studies accomplished by means of neuroimaging techniques suggest the hypothesis of a dichotomy between a “reach-to-grasp” circuit, involving the anterior intraparietal area, the dorsal and ventral premotor cortices (PMd and PMv – Castiello and Begliomini, 2008; Filimon, 2010) and a “reaching” circuit involving the medial intraparietal area and the superior parieto-occipital cortex (Culham et al., 2006). However, the time course characterizing the involvement of these regions during the planning and execution of these two types of movements has yet to be delineated. A functional magnetic resonance imaging study has been conducted, including reach-to-grasp and reaching only movements, performed toward either a small or a large stimulus, and Finite Impulse Response model (Henson, 2003) was adopted to monitor activation patterns from stimulus onset for a time window of 10 s duration. Data analysis focused on brain regions belonging either to the reaching or to the grasping network, as suggested by Castiello and Begliomini (2008). Results suggest that reaching and grasping movements planning and execution might share a common brain network, providing further confirmation to the idea that the neural underpinnings of reaching and grasping may overlap in both spatial and temporal terms (Verhagen et al., 2013). But, although responsive for both actions, they show a significant predominance for either one of the two actions and such a preference is evident on a temporal scale.

Monkey see, monkey reach: action selection of reaching movements in the macaque monkey

Highly efficient systems are needed to link perception with action in the context of the highly complex environments in which primates move and interact. Another important component is, nonetheless, needed for action: selection. When one piece of fruit from a branch is being chosen by a monkey, many other pieces are within reach and visible: do the perceptual features of the objects surrounding a target determine interference effects? In humans, reaching to grasp a desired object appears to integrate the motor features of the objects which might become potential targets - a process which seems to be driven by inhibitory attention mechanisms. Here we show that non-human primates use similar mechanisms when carrying out goal-directed actions. The data indicate that the volumetric features of distractors are internally represented, implying that the basic cognitive operations allowing for action selection have deep evolutionary roots.

[Candidemia epidemiology in Córdoba Argentina. Surveillance study of five institutions]

The incidence rate of invasive infections due to Candida species has increased drastically in the last 20 years, causing a 40% mortality rate in hospitalized patients. In order to comprehend the epidemiology of Candida bloodstream infection, the study was carried out.

MATERIALS AND METHODS

A retrospective study was done based on microbiology laboratory reports from five terciary care hospitals from the city of Cordoba between January 2010 and August 2012.

RESULTS

158 patients had candidemia, the average age was 55,8 years, and 54% of patients were in the intensive care unit. Candida albicans (44%), Candida parapsilosis (22%) and Candida tropicalis (12%) were the main fungi isolated. Candida parapsilosis was commonly associated with catether infections.

CONCLUSIONS

The data from the city of Cordoba showed that C. albicans, C. parapsilosis y C. tropicalis were the more frequent species isolated from blood cultures. This is similar to what is seen in other series published from Argentina and Latinamerica. This study may have implications when it comes to deciding which empiric antifugal agent is best for the treatment of candidemia.

Corticospinal excitability modulation during action observation

This study used the transcranial magnetic stimulation/motor evoked potential (TMS/MEP) technique to pinpoint when the automatic tendency to mirror someone else's action becomes anticipatory simulation of a complementary act. TMS was delivered to the left primary motor cortex corresponding to the hand to induce the highest level of MEP activity from the abductor digiti minimi (ADM; the muscle serving little finger abduction) as well as the first dorsal interosseus (FDI; the muscle serving index finger flexion/extension) muscles. A neuronavigation system was used to maintain the position of the TMS coil, and electromyographic (EMG) activity was recorded from the right ADM and FDI muscles. Producing original data with regard to motor resonance, the combined TMS/MEP technique has taken research on the perception-action coupling mechanism a step further. Specifically, it has answered the questions of how and when observing another person's actions produces motor facilitation in an onlooker's corresponding muscles and in what way corticospinal excitability is modulated in social contexts.

Reach-to-grasp movements in Macaca fascicularis monkeys: the Isochrony Principle at work

Humans show a spontaneous tendency to increase the velocity of their movements depending on the linear extent of their trajectory in order to keep execution time approximately constant. Termed the isochrony principle, this compensatory mechanism refers to the observation that the velocity of voluntary movements increases proportionally with their linear extension. Although there is a wealth of psychophysical data regarding isochrony in humans, there is none regarding non-human primates. The present study attempts to fill that gap by investigating reach-to-grasp movement kinematics in free-ranging macaques. Video footage of monkeys grasping objects located at different distances was analyzed frame-by-frame using digitalization techniques. The amplitude of arm peak velocity was found to be correlated with the distance to be covered, and total movement duration remained invariant although target distances varied. Like in humans, the "isochrony principle" seems to be operative as there is a gearing down/up of movement velocity that is proportional to the distance to be covered in order to allow for a relatively constant movement duration. Based on a centrally generated temporal template, this mode of motor programming could be functional in macaques given the high speed and great instability of posture and joint kinematics characterizing their actions. The data presented here take research in the field of comparative motor control a step forward as they are based on precise measurements of spontaneous grasping movements by animals living/acting in their natural environment.

Motor resonance in left- and right-handers: evidence for effector-independent motor representations

The idea of motor resonance was born at the time that it was demonstrated that cortical and spinal pathways of the motor system are specifically activated during both action-observation and execution. What is not known is if the human action observation-execution matching system simulates actions through motor representations specifically attuned to the laterality of the observed effectors (i.e., effector-dependent representations) or through abstract motor representations unconnected to the observed effector (i.e., effector-independent representations). To answer that question we need to know how the information necessary for motor resonance is represented or integrated within the representation of an effector. Transcranial magnetic stimulation (TMS)-induced motor evoked potentials (MEPs) were thus recorded from the dominant and non-dominant hands of left- and right-handed participants while they observed a left- or a right-handed model grasping an object. The anatomical correspondence between the effector being observed and the observer's effector classically reported in the literature was confirmed by the MEP response in the dominant hand of participants observing models with their same hand preference. This effect was found in both left- as well as in right-handers. When a broader spectrum of options, such as actions performed by a model with a different hand preference, was instead considered, that correspondence disappeared. Motor resonance was noted in the observer's dominant effector regardless of the laterality of the hand being observed. This would indicate that there is a more sophisticated mechanism which works to convert someone else's pattern of movement into the observer's optimal motor commands and that effector-independent representations specifically modulate motor resonance.

Eicosapentaenoic acid modulates CyA-induced proinflammatory cytokine over-expression in osteoblastic cells in vitro

Several adverse outcomes are reported in subjects undergoing long term Cyclosporin A (CyA) treatment. Severe osteopenia has been described in clinical and experimental reports, while beneficial effects of n-3 polyunsaturated fatty acids (PUFAs) on bone metabolism are recognized. In the present study we investigated the effects of n-3 versus n-6 PUFAs on osteoblastic cells treated with CyA, evaluating the expression of interleukin (IL)-1&#223;, interleukin-6 (IL-6), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) in two different experimental protocols and the production of IL-6, IL-1&#223;, and tumor necrosis factor alpha (TNFalpha) in cells challenged simultaneously with CyA and eicosapentaenoic acid (EPA) for 48h. IL-1&#223; and IL-6 up-regulation, induced by CyA, was counteracted by the addition of EPA in both protocols; on the contrary, arachidonic acid (AA) magnified CyA the effects. COX-2 and iNOS levels were not modified by CyA treatment. These in vitro results, that substantiate clinical reports of CyA-induced osteopenia, demonstrate a beneficial effect of EPA on CyA-altered cytokine profile, opening new perspectives in the non-pharmacological management of adverse outcomes in CyA-treated patients.

Search for a low-mass standard model Higgs boson in the ττ decay channel in pp collisions at sqrt[s]=1.96 TeV

We report on a search for the standard model Higgs boson decaying into pairs of τ leptons in pp collisions produced by the Tevatron at sqrt[s]=1.96  TeV. The analyzed data sample was recorded by the CDFII detector and corresponds to an integrated luminosity of 6.0  fb(-1). The search is performed in the final state with one τ decaying leptonically and the second one identified through its semihadronic decay. Since no significant excess is observed, a 95% credibility level upper limit on the production cross section times branching ratio to the ττ final state is set for hypothetical Higgs boson masses between 100 and 150  GeV/c2. For a Higgs boson of 120  GeV/c2 the observed (expected) limit is 14.6 (15.3) the predicted value.