电触觉的皮肤神经机理仿真及实验验证

触觉学已经在很多领域得到应用,如遥控机器人、手术机器人、假肢、娱乐交互界面以及虚拟现实技术等,以此来增强人对机器或者虚拟物体的操作性。电触觉是现在主要的触觉再现措施,即通过改变恒流/恒压电脉冲的频率、脉宽、强度以及脉冲方向等因素,让人产生不同的触觉感。首先通过人体皮肤神经的建模推导出激励函数,并进行仿真研究,通过改变施加在电刺激阵列的电脉冲方向和强度,设计能分别刺激皮下3种刺激感受器（Meissner触觉小体、Merkel触盘、Pancinian环层小体）的实验范式,同时进行了心理物理学实验。10位受试者参加了实验,对食指进行电触觉刺激。正脉冲时采用不同频率（10、30、70、90 Hz）的电脉冲进行刺激,让受试者产生不同级别的振动感;负脉冲时采用不同脉宽（150、200、250、300 μs）的电脉冲进行刺激,让受试者产生不同级别的压力感。受试者对振动和压力的感觉强度进行主观判断。统计结果表明,该模型下的实验模式能够使触觉强度分级平均识别率高达80%以上,同时可通过对刺激电极分布以及电流大小的分析,找到最佳的刺激模式,保证最佳的触觉再现。     

Efficacy of scleral-fixated 3-looped haptics intraocular lens implantation for surgical management of microspherophakia

AIM: To evaluate the safety and efficacy of scleral-fixated 3-looped haptics intraocular lens (IOL) implantation for surgical management of microspherophakia. METHODS: A retrospective case series include 10 microspherophakic patients (15 eyes) who underwent lens removal plus a modified surgical treatment of scleral-fixated 3-looped haptics IOL implantation. The primary outcomes involved visual acuity, intraocular pressure (IOP). Secondary outcomes were spherical equivalent (SE), anterior chamber depth (ACD), corneal endothelial cell density and postoperative complications. RESULTS: After a postoperative follow-up of 17.60±15.44mo, improved visual outcomes can be observed. The uncorrected distance visual acuity (UCVA) logMAR improved from 1.54±0.59 preoperatively to 0.51±0.35 postoperatively (P=0.001), and best corrected visual acuity (BCVA) logMAR improved from 0.97±0.91 preoperatively to 0.24±0.23 postoperatively (P=0.003). Moreover, the SE decreased from -9.58±7.47D preoperatively to -0.65±2.21 D postoperatively (P<0.001). In terms of safety profile, the average IOP decreased from 21.10±12.94 mm Hg preoperatively to 14.03±3.57 mm Hg postoperatively (P=0.044), and the previously elevated IOP of three eyes decreased to the normal range. The ACD increased from 2.25±1.45 mm preoperatively to 3.35±0.39 mm postoperatively (P=0.017). The density of corneal endothelial cells did not change significantly after surgery (P=0.140). The posterior chamber IOLs were well centered and no severe complications were found. CONCLUSION: Lens removal plus the modified surgical treatment of scleral-fixated 3-looped haptics IOL implantation can help in improvement of visual acuity, which can be regarded as a relative safe method for the surgical management of microspherophakia.     

The look and feel of soft are similar across different softness dimensions

The softness of objects can be perceived through several senses. For instance, to judge the softness of a cat''s fur, we do not only look at it, we often also run our fingers through its coat. Recently, we have shown that haptically perceived softness covaries with the compliance, viscosity, granularity, and furriness of materials (Dovencioglu, Üstün, Doerschner, & Drewing, 2020). However, it is unknown whether vision can provide similar information about the various aspects of perceived softness. Here, we investigated this question in an experiment with three conditions: in the haptic condition, blindfolded participants explored materials with their hands, in the static visual condition participants were presented with close-up photographs of the same materials, and in the dynamic visual condition participants watched videos of the hand-material interactions that were recorded in the haptic condition. After haptically or visually exploring the materials, participants rated them on various attributes. Our results show a high overall perceptual correspondence among the three experimental conditions. With a few exceptions, this correspondence tended to be strongest between haptic and dynamic visual conditions. These results are discussed with respect to information potentially available through the senses, or through prior experience, when judging the softness of materials.     

“Can touch this”: Cross‐modal shape categorization performance is associated with microstructural characteristics of white matter association pathways

Previous studies on visuo‐haptic shape processing provide evidence that visually learned shape information can transfer to the haptic domain. In particular, recent neuroimaging studies have shown that visually learned novel objects that were haptically tested recruited parts of the ventral pathway from early visual cortex to the temporal lobe. Interestingly, in such tasks considerable individual variation in cross‐modal transfer performance was observed. Here, we investigate whether this individual variation may be reflected in microstructural characteristics of white‐matter (WM) pathways. We first trained participants on a fine‐grained categorization task of novel shapes in the visual domain, followed by a haptic categorization test. We then correlated visual training‐performance and haptic test‐performance, as well as performance on a symbol‐coding task requiring visuo‐motor dexterity with microstructural properties of WM bundles potentially involved in visuo‐haptic processing (the inferior longitudinal fasciculus [ILF], the fronto‐temporal part of the superior longitudinal fasciculus [SLF_ft] and the vertical occipital fasciculus [VOF]). Behavioral results showed that haptic categorization performance was good on average but exhibited large inter‐individual variability. Haptic performance also was correlated with performance in the symbol‐coding task. WM analyses showed that fast visual learners exhibited higher fractional anisotropy (FA) in left SLF_ft and left VOF. Importantly, haptic test‐performance (and symbol‐coding performance) correlated with FA in ILF and with axial diffusivity in SLF_ft. These findings provide clear evidence that individual variation in visuo‐haptic performance can be linked to microstructural characteristics of WM pathways. Hum Brain Mapp 38:842–854, 2017. © 2016 Wiley Periodicals, Inc.     

Early experience with a patient‐specific virtual surgical simulation for rehearsal of endoscopic skull‐base surgery

Background

With the help of contemporary computer technology it is possible to create a virtual surgical environment (VSE) for training. This article describes a patient‐specific virtual rhinologic surgical simulation platform that supports rehearsal of endoscopic skull‐base surgery. We also share our early experience with select cases.

Methods

A rhinologic VSE was developed, featuring a highly efficient direct 3‐dimensional (3D) volume renderer with simultaneous stereoscopic feedback during surgical manipulation of the virtual anatomy, as well as high‐fidelity haptic feedback. We conducted a retrospective analysis on 10 patients who underwent various forms of sinus and ventral skull‐base surgery to assess the ability of the rhinologic VSE to replicate actual intraoperative findings.

Results

In all 10 cases, the simulation experience was realistic enough to perform dissections in a similar manner as in the actual surgery. Excellent correlation was found in terms of surgical exposure, anatomical features, and the locations of pathology.

Conclusion

The current rhinologic VSE shows sufficient realism to allow patient‐specific surgical rehearsal of the sinus and ventral skull base. Further validation studies are needed to assess the benefits of performing patient‐specific rehearsal.