Of maps and grids

Neuroscience has made remarkable advances in accounting for how the brain performs its various functions. Consciousness, too, is usually approached in functional terms: the goal is to understand how the brain represents information, accesses that information, and acts on it. While useful for prediction, this functional, information-processing approach leaves out the subjective structure of experience: it does not account for how experience feels. Here, we consider a simple model of how a “grid-like” network meant to resemble posterior cortical areas can represent spatial information and act on it to perform a simple “fixation” function. Using standard neuroscience tools, we show how the model represents topographically the retinal position of a stimulus and triggers eye muscles to fixate or follow it. Encoding, decoding, and tuning functions of model units illustrate the working of the model in a way that fully explains what the model does. However, these functional properties have nothing to say about the fact that a human fixating a stimulus would also “see” it—experience it at a location in space. Using the tools of Integrated Information Theory, we then show how the subjective properties of experienced space—its extendedness—can be accounted for in objective, neuroscientific terms by the “cause-effect structure” specified by the grid-like cortical area. By contrast, a “map-like” network without lateral connections, meant to resemble a pretectal circuit, is functionally equivalent to the grid-like system with respect to representation, action, and fixation but cannot account for the phenomenal properties of space.

Optimizing the usage of pupillary based indicators for cognitive workload

The Index of Cognitive Activity (ICA) and its open-source alternative, the Index of Pupillary Activity (IPA), are pupillary-based indicators for cognitive workload and are independent of light changes. Both indicators were investigated regarding influences of cognitive demand, fatigue and inter-individual differences. In addition, the variability of pupil changes between both eyes (difference values) were compared with the usually calculated pupillary changes averaged over both eyes (mean values). Fifty-five participants performed a spatial thinking test, the R-Cube-Vis Test, with six distinct difficulty levels and a simple fixation task before and after the R-Cube-Vis Test. The distributions of the ICA and IPA were comparable. The ICA/IPA values were lower during the simple fixation tasks than during the cognitively demanding R-Cube-Vis Test. A fatigue effect was found only for the mean ICA values. The effects of both indicators were larger between difficulty levels of the test when inter-individual differences were controlled using z-standardization. The difference values seemed to control for fatigue and appeared to differentiate better between more demanding cognitive tasks than the mean values. The derived recommendations for the ICA/IPA values are beneficial to gain more insights in individual performance and behavior during, e.g., training and testing scenarios.

A new mandibular anchorage solution inspired from alpinism

In this article, we are presenting a new mandibular anchorage solution through three clinical cases. This method is based on a mountain climbing technique. Thanks to a simple fixation wire insert in the jaw bone, it is now possible to obtain a backward movement of the mandibular arch and a significant uprighting of the incisors.

A Novel Vesicoscopic Bladder Wall Suture Fixation Technique to Aid Endoscopic Vesicostomy Button Insertion

Background: To describe a novel bladder fixation technique for use during endoscopic vesicostomy button insertion. Methods: After standard cystoscopic visualization of the bladder, a standard 18 G intravenous cannula was inserted into the bladder. A non-absorbable suture thread was placed through this intravenous cannula under cystoscopic vision. The proximal end of the suture was then removed using standard ureteroscopic grasping forceps (3 Fr) through another needle (15 G) inserted next to the initial puncture site (following a path at 30 degrees from the initial puncture tract) into the bladder. The suture ends were brought out of the bladder and tied at the skin level, 2 cm from the intended vesicostomy site. Sutures were removed on the second postoperative day. Results: This fixation technique allows for adequate fixation of the bladder dome to the anterior abdominal wall. These sutures also have less potential for cutaneous scarring and pain. No complications were reported. Conclusion: This simple fixation technique is easily performed using materials found in every urology suite. It also avoids the skills required with other previously reported fixation suture techniques, and can also be utilized for bladder fixation in cases of vesicoscopic laparoscopic or robotic assisted laparoscopic procedures.

A simple and rapid method of repeated tie over dressing

ABSTRACTTie overdressing is commonly used to secure the graft against the raw surface and prevent loss due to of hematoma or seroma. A conventional tie over dressing with silk sutures, is a useful method of securing the graft to raw area. Refixation is difficult when repeated tie over dressings are needed. We assessed a low cost repeated tie over dressing method using sterile sample collection containers and silk suture threads in eight patients. After the graft is applied on the bed, tie-over stitches are taken, and paraffin gauze is applied over with adequate padding; the tie over sutures are passed through the container and the lid is tightened over it to complete the dressing. The lid can be unscrewed easily at any time to inspect the graft and can be easily reapplied in the outpatient department. The skin graft take in all the patients was complete without any seroma or hematoma. A novel and low-cost tie over dressing that enables simple fixation of the dressing, to maintain proper position of grafts that require repeated fixation is reported here.

The experimental study of the hybrid fixation in ACL reconstruction

The article is approaching an interesting topic regarding ACL reconstruction using the hamstring tendons (semitendinosus and gracilis) as the graft. The initial graft fixation after ACL reconstruction is mechanical and it must assure the stability of the system until the biologic integration takes place. No fixation system is as strong as the native ACL insertion. Therefore, hibrid fixation like an improvement of simple fixation is a field worth studying. The fixation shown in this article is the Hybrid fixation consisting of direct fixation with interference screw and an extra cortical fixation over a cortical screw.