Randomizing visual feedback in manual aiming: reminiscence of the previous trial condition and prior knowledge of feedback availability

A trial-by-trial analysis was used to systematically examine the influence of switching visual conditions on visual feedback utilization for a manual aiming movement. In experiment one, vision was randomly manipulated from trial to trial with no more than four consecutive trials in the same visual condition. In experiment two, participants were provided with certainty of visual feedback availability prior to every trial. Results of both studies revealed that movement endpoint variability was most associated with visual feedback availability on the previous trial. Furthermore, correlation analyses comparing movement trajectory at 25, 50 and 75% with movement end (i.e. 100%) revealed that the efficiency of online corrections also depends on the availability of visual feedback on the previous trial. These results suggest that the accuracy of an aiming movement is highly dependent on processing of offline visual information from the preceding trial. This study was supported by a grant from the Natural Sciences and Engineering Research Council of Canada (NSERC) awarded to Luc Tremblay.

---

Methodological problems undermine tests of the ideo-motor conjecture

Recent behavioural research has investigated whether viewing someone perform an action results in activation of that action by the observer. Postulated empirical support for this ‘ideo-motor (IM) conjecture’ typically rests upon two types of experimental paradigm (reaction time and movement tracking tasks). These paradigms purport to show movement facilitation when compatible movements are observed and vice versa, but only for biological stimuli. Unfortunately, these paradigms often contain confounding (and unavoidable) generic stimulus–response compatibility effects that are not restricted to observed human movement. The current study demonstrates in three experiments that equivalent compatibility effects can be produced by non-biological stimuli. These results suggest that existing empirical paradigms may not, and perhaps cannot, support the IM-conjecture.

Modelling the human pharyngeal airway: validation of numerical simulations using in vitro experiments

In the presented study, a numerical model which predicts the flow-induced collapse within the pharyngeal airway is validated using in vitro measurements. Theoretical simplifications were considered to limit the computation time. Systematic comparisons between simulations and measurements were performed on an in vitro replica, which reflects asymmetries of the geometry and of the tissue properties at the base of the tongue and in pathological conditions (strong initial obstruction). First, partial obstruction is observed and predicted. Moreover, the prediction accuracy of the numerical model is of 4.2% concerning the deformation (mean quadratic error on the constriction area). It shows the ability of the assumptions and method to predict accurately and quickly a fluid–structure interaction.

Combining Nonlinear Biometric and Psychometric Models of Cognitive Abilities

It is well-established that genetic factors account for large proportions of individual differences in multiple cognitive abilities. It is also well-established that individual differences in performance on many different cognitive ability measures are strongly correlated. Recent empirical investigations, however, have suggested two interesting qualifications to these well-established findings: Genetic variance in cognitive abilities is higher in richer home environments (gene-by-environment interaction), and common variance in different cognitive abilities is lower at higher levels of overall ability (nonlinear factor structure). Although they have been investigated independently, these two phenomena may interact, because richer environments are routinely associated with higher ability levels. Using simulation we demonstrate how un-modeled nonlinear factor structure can obscure interpretation of gene-by-environment interaction. We then reanalyze data from the National Collaborative Perinatal Project, previously used by Turkheimer et al. (2003; Psychol Science), with a two-step method to model both phenomena.

Dopamine and inhibitory action control: evidence from spontaneous eye blink rates

The inhibitory control of actions has been claimed to rely on dopaminergic pathways. Given that this hypothesis is mainly based on patient and drug studies, some authors have questioned its validity and suggested that beneficial effects of dopaminergic stimulants on response inhibition may be limited to cases of suboptimal inhibitory functioning. We present evidence that, in carefully selected healthy adults, spontaneous eyeblink rate, a marker of central dopaminergic functioning, reliably predicts the efficiency in inhibiting unwanted action tendencies in a stop-signal task. These findings support the assumption of a modulatory role for dopamine in inhibitory action control.

Genetic and Environmental Mediation Between Measures of Personality and Family Environment in Twins Reared Together

In this study we analyzed the etiology of the relationship between personality traits and retrospectively recalled family environment. The data of 226 identical and 168 fraternal twin pairs reared together from the Jena twin study of social attitudes were available. Personality traits were measured using the self- and peer report versions of the German NEO-personality inventory-revised. A German version of Blocks Environmental Questionnaire was applied to measure two broad dimensions of the family environment retrospectively: support and organization. We could replicate earlier findings that retrospective reports of these family environment dimensions were in part genetically influenced. A total of 66% of the genetic variance in support and 24% in organization could be accounted for by heritable variance in self-rated personality. That was replicated by using peer reports of personality, 41% explained genetic variance in support and 17% in organization. Environmental mediations were negligible. This indicates that the relationship between personality and retrospectively recalled family environment is largely genetically mediated.

High genetic diversity of Sappinia-like strains (Amoebozoa, Thecamoebidae) revealed by SSU rRNA investigations

Sappinia diploidea is known as a free-living amoeba of worldwide distribution and has also been reported as causative agent of a brain infection in an immunocompetent young man. In the current study, we were able to isolate eight strains of S. diploidea-like amoebae identified by light microscopy from different habitats. Cultures of all strains were established successfully for molecular characterization. The small subunit ribosomal RNA genes of all strains were sequenced and compared to one another, to the neotype of S. diploidea, and to strains of Sappinia pedata, the only other Sappinia species known to date, from GenBank by multiple sequence alignment and cluster analysis. Altogether, the phylogenetic position of the genus Sappinia within the Thecamoebidae was corroborated; however, it was shown that the genus splits into several well-separated clusters making the establishment of new species within this genus inevitable. Furthermore, two of the S. diploidea-like strains were actually more closely related to S. pedata than to S. diploidea, although the diagnostically relevant standing form which seems to be characteristic for S. pedata was not observed in either of the two strains. Claudia Wylezich and Julia Walochnik have contributed equally to this work.

---

RNAi-dependent and -independent antiviral phenotypes of chromosomally integrated shRNA clones: Role of VASP in respiratory syncytial virus growth

Stable RNA interference (RNAi) is commonly achieved by recombinant expression of short hairpin RNA (shRNA). To generate virus-resistant cell lines, we cloned a shRNA cassette against the phosphoprotein gene of respiratory syncytial virus (RSV) into a polIII-driven plasmid vector. Analysis of individual stable transfectants showed a spectrum of RSV resistance correlating with the levels of shRNA expressed from different chromosomal locations. Interestingly, resistance in a minority of clones was due to mono-allelic disruption of the cellular gene for vasodilator-stimulated phosphoprotein (VASP). Thus, pure clones of chromosomally integrated DNA-directed RNAi can exhibit gene disruption phenotypes resembling but unrelated to RNAi.

Novel preparation techniques for controlling microbubble uniformity: a comparison

In recent years, there has been increasing interest in the use of coated microbubbles as vehicles for ultrasound mediated targeted drug delivery. This application requires a high degree of control over the size and uniformity of microbubbles, in order to ensure accurate dosing of a given drug and to maximise delivery efficiency. Similarly, as more advanced imaging techniques are developed which exploit the complex nonlinear features of the microbubble signal and/or enable quantification of tissue perfusion, the ability to predetermine the acoustic response of a microbubble suspension is becoming increasingly important. Consequently, a number of new preparation technologies have been developed to meet the demand for improved control over microbubble characteristics. The aim of the work described in this paper was to compare a conventional microbubble preparation technique, sonication, with two more recent methods: coaxial electrohydrodynamic atomisation and microfluidic (T-junction) processing, in terms of their ability to produce bubbles which are sufficiently small and stable for in vivo use, microbubble uniformity, relative production rates and other practical and economic considerations.

Primary immune surveillance: some like it hot

The thermal element of fever has been found to be beneficial in models of infectious disease. The contributions of fever-range temperatures to the efficacy of the adaptive immune response have only begun to be delineated. There is accumulating evidence that fever-range thermal stress bolsters primary immune surveillance of lymph nodes and Peyer patches by augmenting lymphocyte extravasation across specialized vessels termed high endothelial venules. Molecular mechanisms have recently come to light by which the thermal component of fever alone may promote lymphocyte trafficking, and thereby the probability of mounting a defense against microbial infection. Acquired knowledge of the molecular changes associated with thermal stress may allow for the development of novel therapies for a variety of disease processes.

Accommodation and Size-Constancy of Virtual Objects

Accommodation has been suspected as a contributor to size illusions in virtual environments (VE) due to the lack of appropriate accommodative stimuli in a VE for the objects displayed. Previous experiments examining size-constancy in VE have shown that monocular cues to depth that accompany the object are a major contributor to correct size perception. When these accompanying cues are removed perceived size varied with the object’s distance from the subject, i.e., visual angle. If accommodation were the dominant mechanism contributing to a visual angle response [due to its action to keep physical objects clear] in this condition, an open-loop accommodation viewing condition might restore size-constancy to this condition. Pinhole apertures were used to open-loop accommodation and examine if size-constancy might be restored when few accompanying monocular cues to depth were present. Visual angle performance when viewing a low cue environment was found with and without the use of the pinhole apertures. Thus, these results signify that accommodation does not play a dominate role in the loss of size-constancy in sparse visual environments often used in VE. These results suggest that size-constancy is driven by the inclusion of the remaining monocular cues to depth in VE as it is in the physical world.

Factor Structure of Planning and Problem-solving: A Behavioral Genetic Analysis of the Tower of London Task in Middle-aged Twins

We examined the genetic architecture of a Tower of London test of planning and problem-solving in 690 middle-aged male twins. Phenotypic analyses revealed only one general factor, but the best-fitting genetic model indicated two correlated genetic factors: speed and efficiency. One variable—number of attempts required to mentally figure the puzzles—loaded on both factors. Shared environmental effects could be dropped with virtually no reduction in model fit. Despite significant nonshared environmental correlations across measures, there was no discernable nonshared environmental factor structure. The correlation between genetic factors (r = 0.46) and the variable loading on both factors could reflect modulation of planning, testing alternatives, and working memory that are required to perform the test. Such coordinated activity is consistent with the notion of a supervisory attentional system, a central executive, or metacognitive ability. The different phenotypic and genetic factor results suggest that relying solely on the former could obscure genetic associations.

Saccadic inhibition underlies the remote distractor effect

The remote distractor effect is a robust finding whereby a saccade to a lateralised visual target is delayed by the simultaneous, or near simultaneous, onset of a distractor in the opposite hemifield. Saccadic inhibition is a more recently discovered phenomenon whereby a transient change to the scene during a visual task induces a depression in saccadic frequency beginning within 70 ms, and maximal around 90–100 ms. We assessed whether saccadic inhibition is responsible for the increase in saccadic latency induced by remote distractors. Participants performed a simple saccadic task in which the delay between target and distractor was varied between 0, 25, 50, 100 and 150 ms. Examination of the distributions of saccadic latencies showed that each distractor produced a discrete dip in saccadic frequency, time-locked to distractor onset, conforming closely to the character of saccadic inhibition. We conclude that saccadic inhibition underlies the remote distractor effect.

A self-paced brain–computer interface for controlling a robot simulator: an online event labelling paradigm and an extended Kalman filter based algorithm for online training

Due to the non-stationarity of EEG signals, online training and adaptation are essential to EEG based brain–computer interface (BCI) systems. Self-paced BCIs offer more natural human–machine interaction than synchronous BCIs, but it is a great challenge to train and adapt a self-paced BCI online because the user’s control intention and timing are usually unknown. This paper proposes a novel motor imagery based self-paced BCI paradigm for controlling a simulated robot in a specifically designed environment which is able to provide user’s control intention and timing during online experiments, so that online training and adaptation of the motor imagery based self-paced BCI can be effectively investigated. We demonstrate the usefulness of the proposed paradigm with an extended Kalman filter based method to adapt the BCI classifier parameters, with experimental results of online self-paced BCI training with four subjects.

A Judd illusion in far-aiming: evidence of a contribution to action by vision for perception

The present study addresses the role of vision for perception in determining the location of a target in far-aiming. Participants (N = 12) slid a disk toward a distant target embedded in illusory Judd figures. Additionally, in a perception task, participants indicated when a moving pointer reached the midpoint of the Judd figures. The number of hits, the number of misses to the left and to the right of the target, the sliding error (in mm) and perceptual judgment error (in mm) served as dependent variables. Results showed an illusory bias in sliding, the magnitude of which was comparable to the bias in the perception of target location. The determination of target location in far-aiming is thus based on relative metrics. We argue that vision for perception sets the boundary constraints for action and that within these constraints vision for action autonomously controls movement execution, but alternative accounts are discussed as well.

Crossmodal interaction in saccadic reaction time: separating multisensory from warning effects in the time window of integration model

In a focused attention task saccadic reaction time (SRT) to a visual target stimulus (LED) was measured with an auditory (white noise burst) or tactile (vibration applied to palm) non-target presented in ipsi- or contralateral position to the target. Crossmodal facilitation of SRT was observed under all configurations and stimulus onset asynchrony (SOA) values ranging from  −500 (non-target prior to target) to 0 ms, but the effect was larger for ipsi- than for contralateral presentation within an SOA range from  −200 ms to 0. The time-window-of-integration (TWIN) model (Colonius and Diederich in J Cogn Neurosci 16:1000, 2004) is extended here to separate the effect of a spatially unspecific warning effect of the non-target from a spatially specific and genuine multisensory integration effect.

Interaction of intensity and order regarding painful events

While stimulus intensity obviously affects degree of pain responding, presentation order effects of stimuli of different intensities on acute pain responses are under-researched. The present study examined the effects of manipulating presentation order of lower and higher pain stimulus intensity. Using 96 undergraduates, this investigation employed a 2 × 2 mixed research design, with pain stimulus sequence as a between-subjects variable and pain stimulus trial as a repeated measure. When the greater pain stimulus intensity was presented last, verbal report of pain was higher. Also, performance of a cognitive task was interrupted the least when the lower stimulus intensity was presented last. Heart rate, however, was highest when the greater stimulus intensity was presented first, and pain tolerance was greatest when the lower stimulus intensity was presented first. Results are discussed in relation to adaptation-level effects, and implications for pain experienced in clinical settings are suggested.

Spontaneous reactions to health risk feedback: a network perspective

Research on the reception of health risk feedback has focused on the analysis of single, researcher-selected cognitive reactions. The full range of spontaneous reactions and their patterns have received little attention. The present paper explores content, interrelations, and adaptivity of spontaneous reactions to health risk feedback from a network perspective. Participants (n = 423) received blood pressure and cholesterol feedback and listed their thoughts afterwards. A network of reactions to health risk feedback was constructed from the responses. Emotions, risk feedback valence, future lifestyle, and expectedness emerged as strong and largely well-connected network nodes, while previously well-researched reactions like feedback acceptance formed small, less connected nodes. The majority of reaction patterns identified through the network appeared adaptive, even after negative feedback. The network provides a potentially useful tool for research and practice, highlighting previously neglected relevant reactions, and providing a group-level background against which individual reactions can be evaluated.