Intrinsic positional memory guides target-specific axon regeneration in the zebrafish vagus nerve

ABSTRACT Regeneration after peripheral nerve damage requires that axons re-grow to the correct target tissues in a process called target-specific regeneration. Although much is known about the mechanisms that promote axon re-growth, re-growing axons often fail to reach the correct targets, resulting in impaired nerve function. We know very little about how axons achieve target-specific regeneration, particularly in branched nerves that require distinct targeting decisions at branch points. The zebrafish vagus motor nerve is a branched nerve with a well-defined topographic organization. Here, we track regeneration of individual vagus axons after whole-nerve laser severing and find a robust capacity for target-specific, functional re-growth. We then develop a new single-cell chimera injury model for precise manipulation of axon-environment interactions and find that (1) the guidance mechanism used during regeneration is distinct from the nerve's developmental guidance mechanism, (2) target selection is specified by neurons' intrinsic memory of their position within the brain, and (3) targeting to a branch requires its pre-existing innervation. This work establishes the zebrafish vagus nerve as a tractable regeneration model and reveals the mechanistic basis of target-specific regeneration.

EXPRESS: Individual Word Activation and Word Frequency Effects during the Processing of Opaque Idiomatic Expressions

Idiom processing studies have paid considerable attention to the relationship between idiomatic expressions as a whole and their constituent words. Although most research focused on the semantic properties of the constituent words, their orthographic form could also play a role in processing. To test this, we assessed both form and meaning activation of individual words during the processing of opaque idioms. In two primed word naming experiments, Dutch native speakers silently read sentences word by word and then named the last word of the sentence. This target word was embedded in either an idiomatic or a literal context, and was either expected/correct in this context (COR), or semantically related (REL) or unrelated (UNREL) to the expected word. The correct target word in the idiomatic context was always part of an opaque idiom. Faster naming latencies for the idiom-final noun than for the unrelated target in the idiomatic context indicated that the idiom was activated as a whole during processing. In addition, semantic facilitation was observed in the literal context (COR<REL<UNREL), but not in the idiomatic context (COR<REL=UNREL). This is evidence that the idiom-final noun was not activated at the meaning level of representation. However, an inhibitory effect of orthographic word frequency of the idiom-final noun indicated that the idiom-final noun was activated at the form level. These results provide evidence in favor of a hybrid model of idiom processing in which the individual words and the idiom as a whole interact on form and meaning levels of representation.

MULTIPLE CLASSIFICATION ALGORITHMS UNIMODAL AND MULTIMODAL TARGET RECOGNITION SYSTEMS

Target recognition is of great importance in military and civil applications – object detection, security and surveillance, access and border control, etc. In the article the general structure and main components of a target recognition system are presented. The characteristics such as availability, distinctiveness, robustness, and accessibility are described, which influence the reliability of a TRS. The graph presentations and mathematical descriptions of a unimodal and multimodal TRS are given. The mathematical models for a probability of correct target recognition in these systems are presented. To increase the reliability of TRS, a new approach was proposed – to use a set of classification algorithms in the systems. This approach permits the development of new kinds of systems - Multiple Classification Algorithms Unimodal and Multimodal Systems (MAUMS and MAMMS). The graph presentations, mathematical descriptions of the MAUMS and MAMMS are described. The evaluation of the correct target recognition was made for different systems. The conditions of systems' effectiveness were established. The modality of the algorithm's recognition probabilitymaximal value determination for an established threshold level of the system's recognition probability was proposed, which will describe the requirements for the quality and, respectively, the costs of the recognition algorithms. The proposed theory permits the system's design depending on a predetermined recognition probability.

Neural specification, targeting, and circuit formation during visual system assembly

Like other sensory systems, the visual system is topographically organized: Its sensory neurons, the photoreceptors, and their targets maintain point-to-point correspondence in physical space, forming a retinotopic map. The iterative wiring of circuits in the visual system conveniently facilitates the study of its development. Over the past few decades, experiments in Drosophila have shed light on the principles that guide the specification and connectivity of visual system neurons. In this review, we describe the main findings unearthed by the study of the Drosophila visual system and compare them with similar events in mammals. We focus on how temporal and spatial patterning generates diverse cell types, how guidance molecules distribute the axons and dendrites of neurons within the correct target regions, how vertebrates and invertebrates generate their retinotopic map, and the molecules and mechanisms required for neuronal migration. We suggest that basic principles used to wire the fly visual system are broadly applicable to other systems and highlight its importance as a model to study nervous system development.

Assessment of Attentional Functioning in Health Professionals of a Brazilian Tertiary Referral Hospital for COVID-19

This study is aimed at assessing differences in basic attentional functioning between substantial and minimal work-related exposure to COVID-19 patients in professionals working in a tertiary referral hospital in Rio de Janeiro, Brazil. Therefore, hospital employees performed a Continuous Visual Attention Test. This test consisted of a 90-second Go/No-Go task with 72 (80%) targets and 18 (20%) nontargets. For each participant, reaction time and intraindividual variability of reaction times of all correct target responses, as well as the number of omission and commission errors, were evaluated. Participants were divided into 2 groups based on their exposure to COVID-19 patients (substantial versus minimal exposure). The substantial exposure group consisted of participants with 24 hours/week or more direct contact with COVID-19 patients. This cut-off was based on the clear division between professionals working and not working with COVID-19 patients and considered that 12-hour and 24-hour daily shifts are common for hospital employees in Brazil. A MANCOVA was performed to examine between-group differences, using age, sleep quality, sex, education level, previous COVID-19 infection, and profession as covariates. Of 124 participants, 80 had substantial exposure and 44 had minimal exposure to COVID-19. The overall MANCOVA reached statistical significance ( P = 0.048 ). Post hoc ANCOVA analysis showed that the substantial exposure group had a statistically significantly higher intraindividual variability of reaction time of all correct target responses ( P = 0.017 , Cohe n ’ s δ = − 0.55 ). This result remained after removing those with a previous COVID-19 infection ( P = 0.010 , Cohe n ’ s δ = − 0.64 ) and after matching groups for sample size ( P = 0.004 , Cohe n ’ s δ = − 0.81 ). No other variables reached statistical significance. Concluding, hospital professionals with a substantial level of exposure to patients with COVID-19 show a significant attention decrement and, thus, may be at a higher risk of accidental SARS-CoV-2 infection.

Automatic target matching

Many photogrametric processes require a large number of points to be collected from numerous digital images. It is imperative that these points be collected accurately, so that precise real-world coordinates may be assigned to points captured in the image. To this end, many techniques have been developed to locate, track and identify image targets. This thesis outlines many of these techniques and presents a target matching solution that has been developed in C++, for the subpixel target location program INDMET . The target matching solution is composed of three elements: an epipolar line program, a cross correlation program and a template least squares matching program. The epipolar line program is used to limit the search area in the right image of a given stereo pair, to the vicinity of a single line. The cross correlation program searches this line to locate possible targets and the template least squares matching program is used to determine the target centre of a black and white image target, once it has been located. It was found that these three programs, working together, had between a 20 and 70 percent chance of locating the correct target, depending on the similarity of elliptical targets in each image. Once found, the program could calculate the target centre to an accuracy of approximately 1/10th of a pixel.

Automatic target matching

Many photogrametric processes require a large number of points to be collected from numerous digital images. It is imperative that these points be collected accurately, so that precise real-world coordinates may be assigned to points captured in the image. To this end, many techniques have been developed to locate, track and identify image targets. This thesis outlines many of these techniques and presents a target matching solution that has been developed in C++, for the subpixel target location program INDMET . The target matching solution is composed of three elements: an epipolar line program, a cross correlation program and a template least squares matching program. The epipolar line program is used to limit the search area in the right image of a given stereo pair, to the vicinity of a single line. The cross correlation program searches this line to locate possible targets and the template least squares matching program is used to determine the target centre of a black and white image target, once it has been located. It was found that these three programs, working together, had between a 20 and 70 percent chance of locating the correct target, depending on the similarity of elliptical targets in each image. Once found, the program could calculate the target centre to an accuracy of approximately 1/10th of a pixel.

Restoring the Patient’s Pre-Arthritic Posterior Slope Is the Correct Target for Maximizing Internal Tibial Rotation When Implanting a PCL Retaining TKA with Calipered Kinematic Alignment

Introduction: The calipered kinematically-aligned (KA) total knee arthroplasty (TKA) strives to restore the patient’s individual pre-arthritic (i.e., native) posterior tibial slope when retaining the posterior cruciate ligament (PCL). Deviations from the patient’s individual pre-arthritic posterior slope tighten and slacken the PCL in flexion that drives tibial rotation, and such a change might compromise passive internal tibial rotation and coupled patellofemoral kinematics. Methods: Twenty-one patients were treated with a calipered KA TKA and a PCL retaining implant with a medial ball-in-socket and a lateral flat articular insert conformity that mimics the native (i.e., healthy) knee. The slope of the tibial resection was set parallel to the medial joint line by adjusting the plane of an angel wing inserted in the tibial guide. Three trial inserts that matched and deviated 2°> and 2°< from the patient’s pre-arthritic slope were 3D printed with goniometric markings. The goniometer measured the orientation of the tibia (i.e., trial insert) relative to the femoral component. Results: There was no difference between the radiographic preoperative and postoperative tibial slope (0.7 ± 3.2°, NS). From extension to 90° flexion, the mean passive internal tibial rotation with the pre-arthritic slope insert of 19° was greater than the 15° for the 2°> slope (p < 0.000), and 15° for the 2°< slope (p < 0.000). Discussion: When performing a calipered KA TKA with PCL retention, the correct target for setting the tibial component is the patient’s individual pre-arthritic slope within a tolerance of ±2°, as this target resulted in a 15–19° range of internal tibial rotation that is comparable to the 15–18° range reported for the native knee from extension to 90° flexion.

Using Virtual Reality to Test for Telepathy: A Proof-of-Concept Study

Telepathy is one of the most commonly reported psi-type experiences and represents the idea that one person can acquire information relating to the thoughts/feelings/intentions of another from a distance via a non-usual route. Typically the procedure involves a Sender and a Receiver who are physically separated whilst the former attempts to relay target information to the latter. Refinements to this paradigm have included placing the Receiver in sensory isolation in an effort to enhance the signal to noise ratio of the signal, as seen in the ganzfeld research. Here the aim was to immerse the Sender in a virtual reality (VR) environment in an effort to boost the transmission of the target whilst keeping the Receiver in partial sensory isolation. Using such a paradigm we tested eleven pairs of participants, each acting as Sender and Receiver across five trials. In each trial the Sender was immersed in a VR environment depicting a positive arousing experience (e.g., skiing downhill, driving a racing car). The Receiver’s task was to identify the correct target image from a set of 5 (i.e., 20% chance) matched for mean valence and arousal. Initial analysis of Receiver performance showed hit rates that did not differ significantly from chance. However, a post-hoc analysis comparing participants top two choices to chance showed a mean hit rate of 52% which was significantly greater than chance (at 40%). Examination of possible associations between hit rate and belief in psi as well as the subjectively rated strength of the relationship between Sender-Receiver pairings only showed a correlation with the psi sub-scale of the RPB. Hence, we argue that participant hit rate is more suggestive than conclusive of a telepathic effect. In addition, we outline a number of methodological refinements which we think could help to improve the viability and effectiveness of using VR.

The Effect of Rewards and Punishments on Learning Action Selection and Execution Components of a Motor Skill

It is unknown whether rewards improve the capability to select appropriate targets for one’s movement (action selection) and/or the movement itself (action execution). Thus, we devised an experimental task wherein participants categorized a complex visual stimulus to determine toward which one of two targets to execute an action (putt a golf ball) on each trial under one of three conditions: reward, punishment, or neutral. After practicing the task under their assigned condition, participants performed an immediate, 24-hr, and 7-day post-test. Results revealed participants putted to the correct target more frequently during the post-tests than the first practice block, and putted more accurately during the post-tests than a pretest. However, the condition in which participants practiced did not moderate post-test performance (for either task component). Additionally, motivation scores explained action selection and action execution for the immediate post-test performance but not long-term retention, suggesting that motivation might be related to immediate performance, but not long-term learning. Further, the present task may be useful for researchers studying action selection and execution, since the task yielded learning effects that could be moderated by factors of interest.