Influence of skull conductivity perturbations on EEG dipole source analysis

PURPOSE: Electroencephalogram (EEG) source analysis is a noninvasive technique used in the presurgical of epilepsy. In this study, the dipole location and orientation errors due to skull conductivity perturbations were investigated in two groups of three-dimensional head models: A spherical head model and a realistic head model. METHODS: In each group, the head model had a brain-to-skull conductivity ratio (Rsigma) within the range of 10-40. Solving the forward problem in the head model with skull conductivity perturbations along with the inverse problem in the baseline head model with Rsigma=20 permitted the derivation of the dipole estimation errors. RESULTS: Perturbations in the skull conductivity generated dipole location and orientation errors: The larger the perturbations, the larger the errors and the error ranges. The dipole orientation error due to skull conductivity perturbations was not great (maximal mean of 5 mm). CONCLUSIONS: Therefore, the influence of skull conductivity perturbations on EEG dipole source analysis cannot be neglected. This study suggests that it is necessary to measure the skull conductivity of the individual patients in order to achieve accurate EEG source analysis.status: publishe

A morphometrical study on the skull of Padovana chicken

A trial was carried out to study the head and skull characteristics in a crested chicken breed with cerebral hernia located in a frontal bony protuberance, an uncrested chicken hybrid strain and their relative crosses. Males and females from five genotypes were used: two Padovana breed varieties (two colour plumages: Padovana argentata, silver -PA- and Padovana camosciata, chamois -PC-), the relative cross (PCxPA), a commercial single comb medium-growing strain (Berlanda gaina - B) and the cross between PC and B (PCxB). As regards skull dimensions B showed heavier, longer, and wider skull than Padovana group (P<0.001); the cross PCxB had skulls heavier than Padovana purebreds (P<0.05). In the Padovana purebreds the frontal bone height varied from 9.2 to 16.2 mm, whereas in the groups with B component the height ranged from 4.2 to 6.8 mm. The frontal bone height was higher in PC and PCxPA than in PA (P<0.01), whereas B and PCxB did not show any bony protuberance. No correlation resulted in Padovana groups between the frontal bone height and the skull length and width. A positive relationship between frontal bone height and skull height was significant only in PCxPA. For the skull characters of PCxPA both the two genotypes seems to be involved and no predominant and relevant effect of only one genotype was seen. The PCxB cross showed relevant differences in the skull morphometry, particularly in the absence of frontal bony protuberance and in the presence of comb

Multi Agent Modelling: Evolution and Skull Thickness in Hominids

Within human evolution, the period of Homo Erectus is particularly interesting since in this period, our ancestors have carried thicker skulls than the species both before and after them. There are competing theories as to the reasons of this enlargement and its reversal. One of these is the theory that Homo Erectus males fought for females by clubbing each other on the head. The other one says that due to the fact that Homo Erectus’ did not cook their food at all, they had to have strong jaw muscles attached to ridges on either side of the skull which prohibited brain and skull growth but required the skull to be thick. The re-thinning of the skull on the other hand might be due to the fact that a thick skull provided poor cooling for the brain or that as hominids started using tools to cut their food and using fire to cook it, they did not require the strong jaw muscles anymore and this trait was actually selected against since the brain had a tendency to grow and the ridges and a thick skull were preventing this. In this paper we simulated both the fighting and the diet as ways in which the hominid skull grew thicker. We also added other properties such as cooperation, selfishness and vision to our agents and analyzed their changes over generations. Keywords: Evolution, Skull Thickness, Hominids, Multi-Agent Modeling, Genetic Algorithm

Floristics, structure and site characteristics of "Melaleuca viridiflora" (Myrtaceae) dominated open woodlands of the wet tropics lowlands

Tropical lowland plant communities in north-eastern Queensland remain under pressure from continuing clearing, fragmentation, exotic species invasion, inappropriate fire regimes, and altered hydrological patterns. Comparatively little scientific research has been conducted on the highly diverse and ecologically significant range of remnant vegetation types. Additionally, most plant communities remain very poorly represented in the existing conservation reserve system. Melaleuca viridiflora Sol. ex Gaertn. open woodlands were selected for investigation based on their relatively simple structure, compared to other lowland communities, and the large extent to which they have been affected by past clearing patterns. A detailed analysis of community structure and composition was conducted at 24 sites throughout the wet-tropics coastal region between Townsville and Cooktown. Surprisingly, a high diversity of structural and floristic types was recorded, with a total of 127 species documented across the 24 sites. Classification analyses of species composition data produced seven or eight main groups of sites (dependent on the statistical technique used), essentially related to a gradient of latitude and rainfall. These floristic groups were not well explained by either species richness, past fire frequencies or soil types. Structural classification analyses based upon DBH data identified six or seven main groups, the singularly most striking of which were sites with annual fire histories. Ordinations based on both the DBH and species composition data produced groupings that supported those detected by the classification techniques. On closer examination of sites with similar fire histories, soil moisture and soil type were both found to have significant effects on community structure and composition. Many of the woodland types recorded are not adequately included (some not at all) in the existing conservation reserve system

Intraoperative Neurophysiological Monitoring for Endoscopic Endonasal Approaches to the Skull Base: A Technical Guide.

Intraoperative neurophysiological monitoring during endoscopic, endonasal approaches to the skull base is both feasible and safe. Numerous reports have recently emerged from the literature evaluating the efficacy of different neuromonitoring tests during endonasal procedures, making them relatively well-studied. The authors report on a comprehensive, multimodality approach to monitoring the functional integrity of at risk nervous system structures, including the cerebral cortex, brainstem, cranial nerves, corticospinal tract, corticobulbar tract, and the thalamocortical somatosensory system during endonasal surgery of the skull base. The modalities employed include electroencephalography, somatosensory evoked potentials, free-running and electrically triggered electromyography, transcranial electric motor evoked potentials, and auditory evoked potentials. Methodological considerations as well as benefits and limitations are discussed. The authors argue that, while individual modalities have their limitations, multimodality neuromonitoring provides a real-time, comprehensive assessment of nervous system function and allows for safer, more aggressive management of skull base tumors via the endonasal route

On Matching Skulls to Digital Face Images: A Preliminary Approach

Forensic application of automatically matching skull with face images is an important research area linking biometrics with practical applications in forensics. It is an opportunity for biometrics and face recognition researchers to help the law enforcement and forensic experts in giving an identity to unidentified human skulls. It is an extremely challenging problem which is further exacerbated due to lack of any publicly available database related to this problem. This is the first research in this direction with a two-fold contribution: (i) introducing the first of its kind skull-face image pair database, IdentifyMe, and (ii) presenting a preliminary approach using the proposed semi-supervised formulation of transform learning. The experimental results and comparison with existing algorithms showcase the challenging nature of the problem. We assert that the availability of the database will inspire researchers to build sophisticated skull-to-face matching algorithms.Comment: International Joint Conference on Biometrics, 201

Pneumoventricle of Unknown Origin. A Personal Experience and Literature Review of a Clinical Enigma

Pneumocephalus (PC) is an uncommon and life-threatening neurological condition. Air within the ventricular system of the brain is also known as Pneumoventricle (PV). It requires emergency treatments to prevent catastrophic neurological outcomes. Head injury is the most common cause of PV, but there are other well-recognized etiologies in case there is no clear radiological evidence of skull discontinuity. Although this clinical entity has been well described in Literature, our report presents the unique feature of describing a purely ventricular PC without evidence of skull base or cranial vault fracture. Therefore, this case presentation explores mysterious causes of fistulous connections with the atmosphere that may lead to air trapped in and around the cranial vault. The aim of the present paper is to report a case of post-traumatic PV without radiological signs of skull base or convexity fracture in a 72-years-old man, underlining the diagnostic and clinical features, and review the relevant Literature