Effects of the model’s handedness and observer’s viewpoint on observational learning

Observation promotes motor skill learning. However, little is known about the type of model and conditions of observation that can optimize learning. In this study, we investigated the effects of the model’s handedness and the observer’s viewpoint on the learning of a complex spatiotemporal task. Four groups of right-handed participants observed, from either a first- or third-person viewpoint, right- or left-handed models performing the task. Observation resulted in significant learning. More importantly, observation of same-handed models resulted in improved learning as compared with observation of opposite-handed models, regardless of the observer’s viewpoint. This suggests that the action observation network (AON) is more sensitive to the model’s handedness than to the observer’s viewpoint. Our results are consistent with recent studies that suggest that the AON is linked to or involves sensorimotor regions of the brain that simulate motor programming as if the observed movement was performed with one’s own dominant hand.     

Whom to ask for help? Children’s developing understanding of other people’s action capabilities

We often rely on other people’s help to accomplish tasks and to attain goals. People, however, differ in their physical action capabilities. Some persons are therefore better able to provide help than others. We investigated 2.5-, 3.5-, and 5-year-old children’s ability to take other person’s action capabilities in a helping situation into account. To this end, they observed a protagonist who needed the help of friends to accomplish several tasks. For each task, two friends were available, but only one was physically able to provide the help. Children were asked to indicate, which partner the protagonist will ask for help. Our results showed a developmental effect with children in the older two groups performing significantly better than those in the youngest group. Additionally, we found evidence that the 5-year-olds outperformed the younger age groups in their ability to justify their choice. Our findings thus suggest that children’s ability to consider others’ physical action capabilities in helping situations develops around 3 years of age. The results are interpreted in terms of children’s ability to perceive others’ affordances. The implication of these findings for theories on the development of action understanding and joint action are discussed.     

The effect of the Müller-Lyer illusion on saccades is modulated by spatial predictability and saccadic latency

Studies investigating the effect of visual illusions on saccadic eye movements have provided a wide variety of results. In this study, we test three factors that might explain this variability: the spatial predictability of the stimulus, the duration of the stimulus and the latency of the saccades. Participants made a saccade from one end of a Müller-Lyer figure to the other end. By changing the spatial predictability of the stimulus, we find that the illusion has a clear effect on saccades (16%) when the stimulus is at a highly predictable location. Even stronger effects of the illusion are found when the stimulus location becomes more unpredictable (19–23%). Conversely, manipulating the duration of the stimulus fails to reveal a clear difference in illusion effect. Finally, by computing the illusion effect for different saccadic latencies, we find a maximum illusion effect (about 30%) for very short latencies, which decreases by 7% with every 100 ms latency increase. We conclude that spatial predictability of the stimulus and saccadic latency influences the effect of the Müller-Lyer illusion on saccades.     

Dopaminergic effects on the implicit processing of distractor objects in Parkinson’s disease

The aim of the present study was to assess the effects of dopaminergic medication on the selection-for-action mechanisms in Parkinson's disease (PD). PD subjects were tested after not having taken medication for at least 12 h ("Off' state) and then retested 1-2 h after medication ("On" state). A three-dimensional kinematic system (ELITE, BTS, Italy) was used to record reach-to-grasp movements to a target object placed at a reaching distance of 30 cm. The target was presented alone or in the presence of distractor objects, which could be of either the same size (compatible distractor) or a different size (incompatible distractor). PD subjects in the Off state were significantly more affected by the presence of the incompatible distractor than in the On state. These results indicate that dopaminergic medication is of benefit in reducing interference effects when distractor objects evoke motor programs that differ from the motor program elicited by the target. Results are discussed in light of the role played by the striatal and mesocortical dopaminergic systems for response selection in basal ganglia disorders.     

Is visual dominance modulated by the threat value of visual and auditory stimuli?

The simultaneous presentation of a visual and an auditory stimulus can lead to a decrease in people’s ability to perceive or respond to the auditory stimulus. In this study, we investigate the effect that threat has upon this phenomenon, known as the Colavita visual dominance effect. Participants performed two blocks of trials containing 40% visual, 40% auditory, and 20% bimodal trials. The first block of trials was identical for all participants, while in the second block, either the visual stimulus (visual threat condition), auditory stimulus (auditory threat condition), or neither stimulus (control condition) was fear-conditioned using aversive electrocutaneous stimuli. We predicted that, when compared with the control condition, this visual dominance effect would increase in the visual threat condition and decrease in the auditory threat condition. This hypothesis was partially supported by the data. In particular, the results showed that the fear-conditioning of the visual stimulus significantly increased the visual dominance effect relative to the control condition. However, the fear-conditioning of the auditory stimulus did not reduce the visual dominance effect but instead increased it slightly. These findings are discussed in terms of the role that attention and arousal play in the dominance of vision over audition.

Proposal for using time estimation training for the treatment of Parkinson’s disease

Studies have shown an association between time perception and the basal ganglia and cortical areas, suggesting a role for these regions in the perception of seconds, minutes, and hours. We present the hypothesis that time estimation training tasks may change the modulatory activity of dopamine in the basal ganglia and the cortical areas related to temporal perception. Through this mechanism, the estimated training time interval can promote a compensatory effect on motor and cognitive performance via a dynamic neural adaptation process. We believe that the training will develop a competition between neural pathways involved in the process of time perception, positively affecting the brain pathways related to Parkinson’s disease, and thereby minimizing the cognitive and motor deficits caused by the disease.     

Mixed observation favors motor learning through better estimation of the model’s performance

Observation contributes to motor learning. It was recently demonstrated that the observation of both a novice and an expert model (mixed observation) resulted in better learning of a complex spatio-temporal task than the observation of either a novice or an expert model alone. In the present study, we sought to determine whether the advantage of mixed observation resulted from the development of a better error detection mechanism. The results revealed that mixed observation resulted in a better estimation of the model’s performance than that with other regimens of observation. The results also suggest that observational learning is improved when observation with knowledge of the results (KR) is followed by an observation phase without KR.     

Methylation levels of the TNFA gene are different between Graves’ and Hashimoto’s diseases and influenced by the TNFA polymorphism

Graves’ disease (GD) and Hashimoto’s disease (HD) are different pathological types of autoimmune thyroid diseases (AITDs). However, the epigenetic differences between these diseases have not been elucidated. DNA methylation is one of the primary epigenetic modifications that reflect environmental influences on gene expression. In this study, we evaluated the methylation status of six CpG sites in the TNFA promoter using pyrosequencing and analyzed the data in combination with functional polymorphisms (?1031?T/C and?+123?C/T) in the TNFA gene to clarify the role of gene methylation on the prognosis of AITDs. We examined the methylation pattern in 52 patients with GD, 60 patients with HD, and 29 healthy controls by pyrosequencing. Additionally, we also genotyped the polymorphisms from 163 patients with GD, 152 patients with HD, and 94 healthy controls using the restriction fragment length polymorphism (RFLP) method. Each proportion of subjects with low methylation of the ?72 CpG site (≤11.9%), low methylation of the ?49 CpG site (≤15.5%), and low methylation of the ?38 CpG site (≤8.9%) was significantly increased in the groups with high concentration of TNF-α (≥0.134?pg/mL). The methylation level of the ?72 CpG site was significantly higher in GD cases (10.7?±?4.9%) than in healthy controls (6.8?±?3.9%). The methylation level of the ?49 and ?38 CpG sites were significantly higher in patients with GD in remission (20.5?±?9.5%, 17.6?±?8.0%, respectively) than in healthy controls (13.0?±?7.6%, 7.9?±?7.3%, respectively). The frequency of the TNFA???1031C carrier (CT?+?CC) is correlated with higher TNF-α production and was significantly higher in GD (35.0%) and HD (39.5%) cases than in controls (19.1%). In the subjects with the TNFA???1031C carrier (CT?+?CC), the methylation level of the ?72 CpG site was significantly higher in GD (11.5?±?5.7%) than in HD (6.0?±?3.4%). However, there was no difference between GD and HD in patients with the TT genotype. Cumulatively, our data indicate the methylation levels of CpG sites in the TNFA gene may be related to the difference between GD and HD in AITDs and may be influenced by the TNFA gene polymorphism.     

Effects of visual feedback on manual tracking and action tremor in Parkinson’s disease

Visual feedback is one of the key elements in on-line control of smooth manual tracking. To in- vestigate the effects basal ganglia dysfunction have on visual feedback control, we have tested six advanced Parkinson’s disease (PD) patients in comparison with normal controls using visually guided wrist tracking tasks. Tracking performance was assessed under three visual conditions: (1) both guiding target and movement cursor were displayed continuously; (2) the target display was turned off for the second half of each trial; or (3) the cursor display, but not the target, was turned off for the second half of each trial. Thus, for the second half of each trial under conditions 2 and 3, no visual feedback of the relationship between the target and the cursor was available. Results showed that although PD patients had significantly larger tracking errors than controls, and errors significantly increased in both PD patients and controls after withdrawing either visual cue, increases in tracking errors in PD were not significantly different from those in controls. Nor were any significant changes found in the frequency (6–8 Hz) or magnitude of the PD patient’s action tremor after withdrawing visual feedback. These results suggest that on-line movement control of wrist tracking movements in advanced PD is not especially reliant on visual feedback. In conjunction with our previous study of multiple sclerosis (MS) patients, the present results confirm that the basal ganglia is less involved in visual guidance of smooth manual tracking than the cerebellar circuits. Received: 24 February 1999 / Accepted: 27 May 1999     

On the relations between affordance and representation of the agent’s effector

The present study aimed to determine whether the representation of object affordances requires specification of the effector potentially interacting with the object: specifically, in this study, vision of the interacting hand. In Experiment 1 we used an apparatus by which a fruit to be reached and grasped was identified by word reading, whereas another (interfering) fruit was visually perceived at the same location as the target. The apparatus allowed visual presentation of the agent’s interacting hand or prevented it. When visually presented, the hand was perceived as still at the start position even when it moved to grasp the fruit. An interference effect on the grasp congruent with the distractor size was observed only when the hand was visible. In Experiment 2, interference was observed also when a hand different from the agent’s own was visually presented. In both Experiments 1 and 2 the visible fruit interfered with the arm’s reach, but the effect was independent of its size and less dependent on the visually-presented hand. A control experiment (Experiment 3) enabled comparison of the interference of visual stimuli on targets identified by word reading (Experiments 1 and 2) with that of objects identified by word reading on visually-presented targets (Experiment 3). The interference induced by visual stimuli was stronger than the interference induced by objects identified by words (i.e. affordances evoked by visual stimuli were stronger than affordances evoked by semantics). Taken together, the results of the present study suggest that the specification of the agent’s effector is necessary for the elicitation of affordances. However, the elicitation of these affordances was observed for interactions between object and hand (grasp), rather than for interactions between object and arm (reach). Finally, our data confirm the influence of semantics on the control of arm movements, though less strong than that due to visual input.     

Frontal brain maturation and the stability of children’s shyness

Recent evidence suggests that relative to nonshy children, shy children exhibit a lower overall frontal EEG alpha/delta ratio (ADR) during middle childhood, possibly reflecting relatively less frontal brain maturation at this age. We examined this same ADR measure in relation to the stability of observed shyness and parent-reported child social anxiety measured across two laboratory visits separated by approximately 1 year during late childhood in 51 children (33% female, age range 10–16 years). We found that the overall frontal ADR score was significantly lower among children with high, stable observed shyness and parent-reported child social anxiety compared to children in the low, stable class. Findings provide convergent evidence suggesting that the stability of shyness in late childhood may be linked to relatively less overall frontal brain maturation at this age. We speculate on the adaptive function of delaying frontal brain maturation in the origins and maintenance of children's shyness.     

Assessment of left ventricular volumes and function by cine-MR imaging depending on the investigator’s experience

AIMS: To analyze the reproducibility of LV volumes calculated by cardiac magnetic resonance imaging (CMRI) and to compare them to those obtained by conventional ventriculography. METHODS: A total of 30 patients with stable ischemic heart disease were prospectively included. Each underwent CMRI twice and ventriculography. Left ventricular end diastolic volume (EDV), end systolic volume (ESV) and LV ejection fraction (EF) were calculated by two radiologists at different level of experience. Intraobserver, interobserver and interstudy variabilities were assessed. RESULTS: The cut off values were: intraobserver variability (EDV, ESV, EF): 9.4 ml, 5.3 ml, 3.3% for well-trained radiologist; 13.1 ml, 7.5 ml, 4.1% for less-trained radiologist. interobserver variability: EDV: 11.7 and 10.4 ml; ESV: 7.0 and 6.6 ml; EF: 3.9 and 4.2%. interstudy variability (EDV, ESV, EF): 11.6 and 12.6 ml, 7.1 and 7.4 ml, 3.9 and 3.5%, for experienced and less-trained observers. Statistical differences were found between CMRI and ventriculography: CMRI underestimation of EDV and EF, overestimation of ESV. CONCLUSIONS: CMRI volumetric quantification of LV volumes and function is highly reproducible at different levels of experience, but not interchangeable with those obtained by ventriculography.     

Parkinson’s disease and immune system: is the culprit LRRKing in the periphery?

Background

Gold nanoparticles (AuNPs) are finding increased use in therapeutics and imaging. However, their toxic effects still remain to be elucidated. Therefore this study was undertaken to study the biochemical effects of AuNPs on rat brain and identify potential biomarkers of AuNP toxicity.

Methods

Male Wister rats weighing 150?C200 g were injected with 20 ??g/kg body weight of 20-nm gold nanoparticles for 3 days through the intraperitoneal route. The rats were killed by carbon dioxide asphyxiation 24 h after the last dose of gold nanoparticle injection. The parameters studied included lipid peroxidation, glutathione peroxidase, 8- hydroxydeoxyguanosine, caspase-3, heat shock protein70, serotonin, dopamine, gamma amino-butyric acid and interferon-??.

Results

In this study AuNPs caused generation of oxidative stress and a decrease of antioxidant enzyme, viz., glutathione peroxidase activity in rat brain. This was accompanied by an increase in 8-hydroxydeoxyguanosine, caspase-3 and heat shock protein70, which might lead to DNA damage and cell death. Gold nanoparticles also caused a significant decrease in the levels of neurotransmitters like dopamine and serotonin, indicating a possible change in the behavior of the treated animals. There was a significant increase in the cerebral levels of IFN-?? in treated animals.

Conclusion

This study concludes that AuNPs cause generation of oxidative stress and an impairment of the antioxidant enzyme glutathione peroxidase in rat brain. AuNPs also cause generation of 8-hydroxydeoxyguanosine (8OHdG), caspase-3 and heat shock protein70 (Hsp70), and IFN-??, which may lead to inflammation and DNA damage/cell death.     

Improved performance of collagen scaffolds crosslinked by Traut’s reagent and Sulfo-SMCC

Collagen scaffolds are frequently employed for applications in regenerative medicine. In previous studies, we affirmed that Traut’s reagent (2-Iminothiolane hydrochloride) and Sulfo-SMCC (4-(N-Maleimidomethyl) cyclohexane-1-carboxylic acid 3-sulpho-N-hydroxysuccinimide ester sodium salt) could covalently bind growth factors on collagen scaffolds. We also observed that crosslinking formed within the collagen scaffolds with excess dosage of Sulfo-SMCC, which improved the biological performance of collagen scaffolds together with growth factors. In order to evaluate changes in capacity caused by crosslinking, Traut’s reagent and adjusted different concentrations of Sulfo-SMCC (0.263, 1.315, 2.63 and 5.26 mM) were used to construct collagen scaffolds with differing extents of crosslinking in this study. The results demonstrated that resistance of collagen scaffolds to enzymatic digestion, cellularization and vascularization in vivo were enhanced by the crosslinking procedure. The cell culture studies indicated that the crosslinking procedure did not influence biocompatibility. Moreover, there were no statistical differences in the degradation rate, cellularization or vascularization among 1.315, 2.63 and 5.26 mM crosslinked groups. These results demonstrated that crosslinking collagen scaffolds with an appropriate amount of Traut’s reagent and Sulfo-SMCC was an effective and safe method to modify naturally derived collagen scaffolds with notable potential uses in tissue regeneration.     

What is the role of motor simulation in action and object recognition? Evidence from apraxia

An important issue in contemporary cognitive neuroscience concerns the role of motor production processes in perceptual and conceptual analysis. To address this issue, we studied the performance of a large group of unilateral stroke patients across a range of tasks using the same set of common manipulable objects. All patients (n = 37) were tested for their ability to demonstrate the use of the objects, recognize the objects, recognize the corresponding object-associated pantomimes, and imitate those same pantomimes. At the group level we observed reliable correlations between object use and pantomime recognition, object use and object recognition, and pantomime imitation and pantomime recognition. At the single-case level, we document that the ability to recognize actions and objects dissociates from the ability to use those same objects. These data are problematic for the hypothesis that motor processes are constitutively involved in the recognition of actions and objects and frame new questions about the inferences that are merited by recent findings in cognitive neuroscience.     

Harvey,by Hercules! The Hero of the Blood’s Circulation

This article continues the analyses in Medical History 52 (2008), 73–90, 365–86 of William Harvey’s self-understanding as the philosopher and discoverer of the blood’s circulation. Harvey brilliantly and subversively assumed the persona of the mythological Hercules to embody his own anatomical labour in De motu cordis et sanguinis (1628). He reprised the role in self-defence against accusations in the College of Physicians, London, of his breach of faith with medical tradition. Harvey sought to usurp the medical epithet ‘a second Hercules’ by reforming humanist dependence on ancient texts as authoritative medicine. A knowledge of the theory and practice of Renaissance humanism discloses his identification with the Herculean labour of cleansing the Augean stable. He employed anatomical demonstration against Galen’s porous cardiac septum, which admitted blood across the ventricles. Harvey’s oath mehercule swore against Galen’s Dia to assert the necessity of opening an alternate route for the blood flow. His Herculean labour was to dam the cardiac septum and divert the blood flow into a continuous channel through the arteries and veins. His circulation of the blood also imitated Hercules’ successful dependence on the force of the water flow to flush the Augean stable. Harvey’s copia did not denote a quantitative amount but a powerful supply. Harvey aspired to be, like Hercules, immortal, a term which the College belatedly acknowledged. This cultural analysis exposes Harvey’s professional issues and personal ambitions, so to promote a fuller understanding of his historic role in medical discovery. Keywords and phrases : William Harvey, Blood, Circulation of; Septum, Hercules, Augean Stables, SwearingThe virile oath mehercule exceeded the discipline of William Harvey’s masterful Exercitatio anatomica de motu cordis et sanguinis in animalibus [An anatomical exercise on the movement of the heart and the blood in animals] (1628). ¹ Medical texts were not in the habit of swearing. Where they did swear – by Hercules, and by Zeus or Jove – marked the arguments Harvey swore in his ambition to alter the history of medicine from tradition to science. ² Although the exclamation has been credited as ‘colourful prose’, ³ most English translations have avoided its literal sense. Renditions have been ‘by my troth’, ‘in fact’, ‘in faith’, ‘damn it’, ‘damme, and ‘in God’s truth’. ⁴ A single editorial revision told the truth, ‘by Hercules’. ⁵ The translator commissioned by the Royal College of Physicians for the tercentenary version rehearsed previous efforts, then explained his own expletive. ‘It took me two hours to think of “damme” as a sufficiently dramatic translation of “mehercule”, but the Oxford English Dictionary then assured me that in the form “Damn me” it was in use as early as 1645, and I felt that the two hours had been well spent in getting the effect that Harvey had, to my mind, intended by his use of a particular Latin word’. ⁶ Yet the synonym for mehercule in good Renaissance English was ‘by George’, for the dragon slayer and national saint. ⁷ Harvey chose the anachronism deliberately. His rhetoric displayed his personal character and professional end, as he brilliantly but subversively assumed the persona of Hercules to embody his own labours.     

What is the role of motor simulation in action and object recognition? Evidence from apraxia

An important issue in contemporary cognitive neuroscience concerns the role of motor production processes in perceptual and conceptual analysis. To address this issue, we studied the performance of a large group of unilateral stroke patients across a range of tasks using the same set of common manipulable objects. All patients (n = 37) were tested for their ability to demonstrate the use of the objects, recognize the objects, recognize the corresponding object-associated pantomimes, and imitate those same pantomimes. At the group level we observed reliable correlations between object use and pantomime recognition, object use and object recognition, and pantomime imitation and pantomime recognition. At the single-case level, we document that the ability to recognize actions and objects dissociates from the ability to use those same objects. These data are problematic for the hypothesis that motor processes are constitutively involved in the recognition of actions and objects and frame new questions about the inferences that are merited by recent findings in cognitive neuroscience.