Saliency-guided neural prosthesis for visual attention: Design and simulation

Recently the authors showed that a computational model of visual saliency could account for changes in gaze behavior of monkeys with damage in the primary visual cortex. Here we propose a neural prosthesis to restore eye gaze behavior by electrically stimulating the superior colliculus to drive visual attention. The saliency computational model is used to calculate the stimulation parameters from a real-time camera stream. Our simulations demonstrate that electrodes implanted in the superior colliculus at 1.0 mm spacing are, in principle, able to recover specifically those visual attention behaviors which are lost when the primary visual cortex is damaged.     

Branching of mandibular canal on cone beam computed tomography images

BackgroundMandibular neurovascular canal contents may be vulnerable to damage during mandibular surgical procedures. Greater knowledge of the location and configuration of the mandibular canal can help in the safe performance of these procedures in the dental clinic. Cross-sectional CBCT imaging is a good modality for studying the course, location, configuration and accessory branches of the mandibular canal. The aim of this study was to observe the branching of the mandibular canal at different segments of the mandible and mandibular tooth groups.MethodsCBCT images of 116 mandibular halves were included in this study. The presence of secondary branching of the mandibular canal in the ramus, retromolar area, molar and premolar teeth as well as the length, diameter and angle of these branches were observed.Resultssixty nine mandibular halves (59.5%), had a main canal with no branching, There were 36 IAC (31%) with one, 8 (6.9%) with two, 2 (1.7%) with three and 1(0.9%) with 5 accessory branches. Of these secondary branches, 16 (25.4%) were in the ramus, 16(25.4%) in the retromolar, and 31(49.2%) in the molar regions.ConclusionAdvanced cross-sectional imaging modalities especially CBCT is a suitable tool for observing anatomic characteristics of mandibular canal to preserve this vital structure in surgical procedures.     

Caval replacement strategy in pediatric retroperitoneal tumors encasing the vena cava: a single-center experience and review of literature

Background

Complete encasement of the inferior vena cava by retroperitoneal tumors is rare. Although replacement of the vena cava has been considered for various conditions in adults, it is rarely used in children except for challenging resections and as a last chance approach – often aiming more at debulking than cure.

Fate of mandibular canals displaced by enlarged cystic lesions: does the inferior alveolar neurovascular bundle relocate to its original position?

Our aim was to identify the positional changes of the inferior alveolar neurovascular bundle and evaluate the relocation of the displaced mandibular canal after enucleation of a cyst. Seventy patients (72 sites) who had had cysts enucleated were divided into three groups based on the degree of encroachment of the cystic lesion into the mandibular canal and whether a bone graft had been inserted after the cyst had been enucleated. The mean (range) of patients’ ages was 45 (18–75) years, and there were 29 male and 41 female patients. Group A comprised cysts with encroachment on the mandibular canal that were enucleated without a bone graft; Group B consisted of cysts with no encroachment of the mandibular canal, but were enucleated without a bone graft; and Group C comprised cysts with encroachment of the mandibular canal that were enucleated with a bone graft. The displacement of the mandibular canal was identified from analysis of computed tomographic (CT) images. Changes in the position of the mandibular canal were measured on panoramic radiographs. The mandibular canal was repositioned superiorly by a mean (SD) of 2.4 (1.65) mm after enucleation of the cyst, which was significant in Group A (p < 0.001), but not in Groups B and C. These results indicate that the displaced inferior alveolar neurovascular bundles that were not surrounded by bony canal tended to relocate towards a supposedly normal position, and after enucleation of the cyst the mandibular canal was remodelled in this new location. This tendency to relocate was blocked by bone grafting. Bone grafts are therefore recommended in cases where enough bony height is required for future insertion of implants.     

长期服药精神病患者双肾下极脂肪囊的超声评价

目的探讨双肾下极脂肪囊(inferior pole area of perirenal fat,IPAPF)可否作为长期服抗精神病药患者心血管病的危险因素。方法纳入106例长期服药精神病患者作为研究组,112例体检人群作为对照组,比较两组一般资料、血脂及超声测量IPAPF。结果研究组HDL-C明显低于对照组,双肾下极脂肪囊面积明显高于对照组,差异有统计学意义(P<0.05)。两组间TC、TG、LDL-C、FBD差异没有统计学意义(P>0.05)。HDL-C、双肾下极脂肪囊呈负相关(r=-0.37,P<0.01)。结论双肾下极脂肪囊与反映冠心病风险的指标存在相关,因此超声测量双肾下极脂肪囊能反映长期服抗精神病药患者心血管病的风险。     

Dexamethasone promotes regeneration of crushed inferior alveolar nerve by inhibiting NF-κB activation in adult rats

PurposeNuclear factor kappa B (NF-κB), which is closely related to inflammation, has become a topic of interest for research. The aim of this study is to investigate the effects of dexamethasone (Dex), an inhibitor of NF-κB, on inferior alveolar nerve injury in adult rats.Materials and methodsThe crushed inferior alveolar model is established in Wistar rats and they are randomly divided into three groups according to treatment: pyrrolidine dithiocarbamate (PDTC), dexamethasone (Dex), and saline (physiological saline). After treatment, the rats are respectively sacrificed at 3, 7, and 14 d, and inferior alveolar nerves are extracted for histochemical and western blot analysis.ResultCompared with the PDTC and saline groups, nerve fibers in the Dex group are regularly arranged with few vacuoles, which is similar to normal inferior alveolar nerves. Immunofluorescent results show significantly decreased NF-κB expression in the Dex group. Western bolt shows higher expression of GAP-43 and lower expression of NF-κB.ConclusionTaken together, all results show that dexamethasone significantly improved the regeneration of crushed inferior alveolar nerves by inhibiting NF-κB activation in adult rats.     

Subacute sclerosing panencephalitis with bilateral inferior collicular hyperintensity on magnetic resonance imaging brain

Subacute sclerosing panencephalitis (SSPE) is chronic encephalitis occurring after infection with measles virus. An 8-year-old boy presented with progressive behavioral changes, cognitive decline and myoclonic jerks, progressing to a bed bound state over 2 months. Magnetic resonance imaging (MRI) brain showed T2-weighted hyperintensities in the subcortical areas of the left occipital lobe and brachium of the inferior colliculus on both sides. EEG showed bilateral, synchronous periodic discharges. Serum/cerebrospinal fluid measles IgG titer was significantly positive. The overall features were suggestive of SSPE. MRI finding of bilateral inferior colliculus changes on MRI without significant involvement of other commonly involved areas suggests an uncommon/rare imaging pattern of SSPE.     

Age-Related Changes in the Relationship Between Auditory Brainstem Responses and Envelope-Following Responses

Hearing thresholds and wave amplitudes measured using auditory brainstem responses (ABRs) to brief sounds are the predominantly used clinical measures to objectively assess auditory function. However, frequency-following responses (FFRs) to tonal carriers and to the modulation envelope (envelope-following responses or EFRs) to longer and spectro-temporally modulated stimuli are rapidly gaining prominence as a measure of complex sound processing in the brainstem and midbrain. In spite of numerous studies reporting changes in hearing thresholds, ABR wave amplitudes, and the FFRs and EFRs under neurodegenerative conditions, including aging, the relationships between these metrics are not clearly understood. In this study, the relationships between ABR thresholds, ABR wave amplitudes, and EFRs are explored in a rodent model of aging. ABRs to broadband click stimuli and EFRs to sinusoidally amplitude-modulated noise carriers were measured in young (3–6 months) and aged (22–25 months) Fischer-344 rats. ABR thresholds and amplitudes of the different waves as well as phase-locking amplitudes of EFRs were calculated. Age-related differences were observed in all these measures, primarily as increases in ABR thresholds and decreases in ABR wave amplitudes and EFR phase-locking capacity. There were no observed correlations between the ABR thresholds and the ABR wave amplitudes. Significant correlations between the EFR amplitudes and ABR wave amplitudes were observed across a range of modulation frequencies in the young. However, no such significant correlations were found in the aged. The aged click ABR amplitudes were found to be lower than would be predicted using a linear regression model of the young, suggesting altered gain mechanisms in the relationship between ABRs and FFRs with age. These results suggest that ABR thresholds, ABR wave amplitudes, and EFRs measure complementary aspects of overlapping neurophysiological processes and the relationships between these measurements changes asymmetrically with age. Hence, measuring all three metrics provides a more complete assessment of auditory function, especially under pathological conditions like aging.