Amount Of Cortex Research Articles

Obsidian lithic technology: Chaîne opératoire and symbolic meaning in the Northern Hualfín Valley (Northwest Argentina) during the Late Inka period

The main objective of this research is to analyse the lithic technology applied to obsidian, a raw material popular amongst pre-Columbian populations from Northwestern Argentina (NWA) because of its social and symbolic value. The analysed assemblage comes from the archaeological site of Villavil 2 (VV2), located in the Hualfín Valley (Catamarca, Argentina) and distant ca. 100 - 200 kms from the nearest sources of this raw material. VV2 was discovered in 2015 by one of the authors and shows a particular presence of rock art which had not previously been registered in this area. The site was associated to the Late and Inka Period (ca. 10th - 16th centuries CE). So far, we suggest that this was a place of temporal, but periodical use that best fits with what we would call a ceremonial space.
 The assemblage comprises the totality of obsidian elements collected from both superficial and stratigraphic contexts. It was divided into three typological classes: tools (projectile points), flakes with natural sharp edges (FNSE) and waste products (WP). We did not identify the presence of cores. The analysis considered the following variables: knapping methods and techniques, size, amount of cortex, flake type and edge types.
 At VV2, points are the only retouched tools made of obsidian. They correspond to the triangular unstemmed concave-based type, very common during the Late-Inka Periods, and they were shaped using the perimetral bifacial pressure technique, possibly from flake blanks. FNSEs’ size is small, and they present scarce cortex. On the other hand, the abundance of very small-sized WPs is remarkable. They were found in the same stratigraphic context and attest a complete finish of the points (edge retouch).
 The results let us infer that the point-shaping tasks were carried out in situ. Moreover, the implemented technology involved both major production efforts and skills, that contrast with those involved in local raw material knapping. It is possible that this curated strategy was not related to the difficulty of accessing this allochthonous material. Instead, these choices could reflect social and symbolic meanings. According to linguistic and ethnohistoric information, the obsidian brightness and transparency are propitiatory to win the favour of the w'akas. Furthermore, in NWA the obsidian long-distance exchange is an ancient pre-Columbian tradition that lasted for a long time. Obtaining obsidian could display the ability of a social group to access distant resources and legitimize their political status. Nevertheless, we cannot forget that this raw material also was very important for making different artefacts for subsistence activities.

How does the presence of the pathologist affect the tissue adequacy and what are the factors affecting the pathologist in proficiency assessment, during percutaneous kidney biopsy?

Objectives: For optimal histomorphological examination, adequacy of kidney biopsy tissue
 should be obtained. In this study, the effect of a pathologist informing the radiologist about
 tissue adequacy during the biopsy procedure on obtaining tissue adequacy was examined.
 Furthermore, we aimed to determine the criteria that the pathologist considered in determining
 tissue adequacy and the conditions affecting the decision to increase the number of core
 biopsies, as these have not been previously examined in the literature.
 Materials and Methods: Tissues containing less than 10 glomeruli were considered
 inadequate. In some patients, a pathologist accompanied the radiologist during the procedure.
 Tissue adequacy ratios and biopsy sample numbers were calculated between the two
 conditions. In the samples taken with the pathologist, the factors affecting the locality
 decision of the pathologist (cortex/medulla amount, presence of glomerular pathology(global,
 segmental, crescentic glomeruli) presence of tubular injury, proteinuria; interstitial
 inflammation and interstitial fibrosis/tubular atrophy ratios, account of normal glomeruli)
 were examined.
 Results: Giving tissue adequacy information during the biopsy procedure had a positive
 effect on tissue adequacy. The amount of cortex is one of the qualification criteria for the
 pathologist. The presence of proteinuria and 50% or more inflammation in tissues with
 sufficient cortex increased the number of biopsy samples.
 
 Conclusion: Determination of tissue adequacy during kidney biopsy is an important and
 necessary method. The amount of cortex is one of the important parameters in tissue
 adequacy.

Evaluating Invasive EEG Implantations with Structural Imaging Data and Functional Scalp EEG Recordings from Epilepsy Patients.

Seizures in patients with medically refractory epilepsy (MRE) cannot be controlled with drugs. For focal MRE, seizures originate in the epileptogenic zone (EZ), which is the minimum amount of cortex that must be treated to be seizure free. Localizing the EZ is often a laborious process wherein clinicians first inspect scalp EEG recordings during several seizure events, and then formulate an implantation plan for subsequent invasive monitoring. The goal of implantation is to place electrodes into the brain region covering the EZ. Then, during invasive monitoring, clinicians visually inspect intracranial EEG recordings to more precisely localize the EZ. Finally, the EZ is then surgically ablated, removed or treated with electrical stimulation. Unfortunately success rates average at 50%. Such grim outcomes call for analytical assistance in creating more accurate implantation plans from scalp EEG. In this paper, we introduce a method that combines imaging data (CT and MRI scans) with scalp EEG to derive an implantation distribution. Specifically, scalp EEG data recorded over a seizure event is converted into a time-gamma frequency map, which is then processed to derive a spectrally annotated implantation distribution (SAID). The SAID represents a distribution of gamma power in each of eight cortical lobe/hemisphere partitions. We applied this method to 4 MRE patients who underwent treatment, and found that the SAID distribution overlapped more with clinical implantations in success cases than in failed cases. These preliminary findings suggest that the SAID may help in improving EZ localization accuracy and surgical outcomes.

All Regions of Mouse Brain Are Dependent on Selenoprotein P for Maintenance of Selenium

The brain and testis retain selenium better than other tissues during selenium deficiency. Studies of mice with selenoprotein P (Sepp1) deleted (Sepp1−/− mice) showed that brain and testis selenium levels are largely dependent on Sepp1. Therefore, we examined tissue selenium in mice fed varying amounts of selenium and in Sepp1−/− mice to characterize better the role(s) of Sepp1. Mice were fed a selenium-deficient diet for 8 wk supplemented with selenium as selenite from none to 0.25 mg/kg diet and tissue selenium was measured. Brain and testis maintained their selenium better than did liver, kidney, and muscle when dietary selenium was limiting but testis selenium fell sharply in the group fed the deficient diet. Brain retained its selenium well, even in the group fed the deficient diet. After intravenous injection of 75Se-Sepp1 into Sepp1−/− and Sepp1+/+ mice, qualitative differences between brain and testis 75Se uptake were noted, further suggesting differences in their uptake of selenium from Sepp1. Finally, selenium was measured in brain regions of Sepp1−/− and Sepp1+/+ mice fed the diet supplemented with 1 mg selenium/kg and Sepp1+/+ mice fed the deficient diet. Deletion of Sepp1 and selenium deficiency each lowered selenium a similar amount in cortex, midbrain, brainstem, and cerebellum. Selenium in the hippocampus was lowered by deletion of Sepp1 but not by selenium deficiency. These results suggest that Sepp1 is more important for maintaining selenium in the hippocampus than in other brain regions. They also confirm the position of the brain at the apex of the organ selenium hierarchy.

Peripheral influences during development of the CNS

The amount of cortex devoted to the representations of each sensory system varies dramatically between different species of mammal, and these differences usually reflect the species-specific emphasis and elaboration of different sensory organs. Furthermore, the central representations of sensory systems closely preserve details of their associated receptor fields. For example, the pattern of whiskers on the snout of a mouse or a rat is represented first by barrelettes in the brain stem, then by barreloids in the thalamus and finally by barrels in the cortex. And in primates a disproportionately large area of visual cortex is devoted to representing the high density of photoreceptors in the fovea.The developmental specification of cortical areas has a genetic component, although complex interactions with the periphery are also involved. Sensory organs are able to influence the development of their central representations through a variety of mechanisms, including activity-dependent synaptic plasticity and competition for neurotrophic factors. Because information about the density, topographical arrangement and diversity of receptors can be provided online by the periphery, it does not have to be duplicated in the developmental program of the brain. This gives the brain the flexibility to adapt to the body in which it finds itself, allowing variability in the periphery to be accommodated without specific changes to the brain-wiring program.The extent to which the cortex can accommodate changes in the periphery has been demonstrated by recent experiments with North American opossums [1xMassive cross-model cortical plasticity and the emergence of a new cortical area in developmentally blind mammals. Kahn, D.M. and Krubitzer, L. Proc. Natl. Acad. Sci. U. S. A. 2002; 99: 11429–11434Crossref | PubMed | Scopus (79)See all References[1]. A marsupial was chosen because the extended period of extra-uterine development allows direct access to early stages that are intra-uterine in eutherian mammals. Animals were blinded by bilateral enucleation and then allowed to develop to adulthood. Electrophyioslogical and architectonic maps of the cortex revealed marked reorganization of the sensory areas. Primary visual cortex was greatly reduced, whereas the areas of cortex responsive to either somatosensory or auditory stimuli were expanded. In addition, a new cortical field was identified in which cells were responsive to both somatosensory and auditory stimuli. The results show both the dramatic plasticity of the wiring program of the brain and the influence of the sensory periphery on cortical development. They also provide an invaluable hint as to one mechanism by which new cortical areas emerge during evolution.

The organization of neocortex in mammals: are species differences really so different?

By examining a variety of mammals, it is possible to determine common features of cortical organization, and from these infer homologies across species. Such analysis also enables differences in the organization of the neocortex to be identified. Species differ in the amount of cortex that is devoted to a particular sensory system, in the size and configuration of a cortical field, in the number of cortical fields, and in the pattern of connections of homologous fields. It is suggested that the plan of organization that is retained is the result of homologous developmental events, and that modifications to this plan are generated by a limited set of mechanisms. These types of changes to the common network might account for the sensory and behavioural diversity that is observed in extant mammals.

Development of metabolic activity patterns in the somatosensory cortex of cats

1. The development of cortical responses to somatic stimulation was studied in kittens 2-5 wk of age using the 2-deoxyglucose (2DG) technique. During the 2DG experiment each kitten received an innocuous intermittent vertical displacement stimulus to the forepaw. 2. The pattern of metabolic activity was substantially different in young animals compared with adults. In the individual autoradiographs of the 2-wk-old kittens stimulus-evoked 2DG uptake in primary somatosensory cortex was localized to a small spot in the upper portion of the cortex, whereas in the adult the label extended vertically through the cortical layers and appeared more column-like. Individual patches of label were substantially smaller and less dense in young animals. Over a period of several weeks the evoked activity evolved to the more extensive adult pattern. The 2DG uptake displayed a mature distribution by approximately 4-5 wk of age. During this period, the cortical architecture also evolved from an immature to a mature arrangement. 3. The evoked activity was reconstructed into two-dimensional maps; the distribution of label > or = 1.5 SD above background was considered to be stimulus related. In the adult, the pattern appeared as a strip or strips of increased metabolic activity that extended in the rostrocaudal direction for approximately 1 mm. In contrast, the activity pattern in animals 2-4 wk old was less discretely organized into "strips" and was more diffusely spread over several mms of somatosensory cortex. The two-dimensional pattern gradually coalesced into a more localized strip by approximately 4-5 wk of age. Although the pattern of label was more widespread in the young animals, the absolute distance of the spread of activity did not vary substantially, regardless of the age of the animal. 4. Other measurements regarding the distribution of activity at different ages indicate that the amount of cortex activated increases in absolute terms, although the percent of cortex activated by the stimulus decreases. The overall intensity of the 2DG uptake as measured on the two-dimensional maps increases with age, as does the variability of the 2DG uptake; a wider range of intensity values is seen in the adult. Plots created from the individual two-dimensional reconstructions allowed a measure of "patch strength" at different ages. These histograms relate the most intense region of uptake in a given map to the spatial distribution of activity spreading in the medial and lateral directions.(ABSTRACT TRUNCATED AT 400 WORDS)

Age-dependent differences in reorganization of primary somatosensory cortex following low thoracic (T12) spinal cord transection in cats

The organization of primary somatosensory cortex was examined in chronic spinal cats that had sustained cord transection at T12 at 3 ages: 2 and 6 weeks of age, and as adults. Five months to 1 yr following transection, the deprived cortex was mapped electrophysiologically (multiunit recordings). The topographical organization found at each age was compared to that present in normal adults to study effects of developmental age on the ability of the somatosensory system to adjust to changes in afferent input. Cortical responses to deprivation of somatosensory input were age dependent. In animals cord transected at 2 weeks of age, the remaining somatic afferent input excited both its normal cortical area and the area normally reserved for the hindlimb. This resulted in 2 somatotopic maps of the rostral trunk and forelimb. In contrast, in cats spinalized at 6 weeks of age, there was only 1 map for the remaining somatosensory input that was distributed across the mediolateral axis of the primary somatosensory cortex. As a result, the remaining somatosensory input was shifted medially from its normal position and was narrower with respect to the rostrocaudal area driven by light tactile input. The amount of cortex that each body region could excite was essentially the same as in normal animals. In adults, a third response was observed; regions normally devoted to forelimb and trunk appeared to be unchanged, and the region previously serving the hindlimb responded only to a limited extent, and only to tactile stimulation of the trunk. In all cases, however, some sites in the cortex could be excited by parts of the body that in normal animals were served by cortical regions from 3 to 10 mm away, a distance much in excess of the maximum extent of reported thalamocortical overlap. We suggest that the various patterns of cortical organization observed at different ages reflect different developmental processes that are active at the time of transection. Further, we hypothesize that often, in major denervations such as spinal cord transection, a significant component of the reorganization occurs at synaptic levels below the cortex in young animals.

The role of the epidermis and cortex in gravitropic curvature of maize roots.

In order to determine the role of the epidermis and cortex in gravitropic curvature of seedling roots of maize (Zea mays L. cv. Merit), the cortex on the two opposite flanks was removed from the meristem through the growing zone; gravitropic curvature was measured with the roots oriented horizontally with the cut flanks either on the upper and lower side, or on the lateral sides as a wound control. Curvature was slower in both these treatments (53 degrees in 5 h) than in intact roots (82 degrees), but there was no difference between the two orientations in extent and rate of curvature, nor in the latent time, showing that epidermis and cortex were not the site of action of the growth-regulating signal. The amount of cortex removed made no difference in the extent of curvature. Curvature was eliminated when the endodermis was damaged, raising the possibility that the endodermis or the stele-cortex interface controls gravitropic curvature in roots. The elongation rate of roots from which just the epidermis had been peeled was reduced by 0.01 mM auxin (indole-3-acetic acid) from 0.42 to 0.27 mm h-1, contradicting the hypothesis that only the epidermis responds to changes in auxin activity during gravistimulation. These observations indicate that gravitropic curvature in maize roots is not driven by differential cortical cell enlargement, and that movement of growth regulator(s) from the tip to the elongating zone is unlikely to occur in the cortex.

Relation of the heat resistance of bacterial spores to chemical composition and structure II. Relation to cortex and structure

The relation between the amount of cortex, measured as total hexosamine, as diaminopimelic acid and as muramic lactam, and the heat resistance of spores of five different strains of Bacillus stearothermophilus was studied. Electron micrographs of thin sections of the spores were made to relate the structure of the spores to chemical and thermal characteristics. It was found that the amount of the cortex was significantly related to heat resistance of the spores. Strains with more electron-dense and better organized cortices were found to express higher heat resistance.

Relationship between cortex content and properties of Bacillus sphaericus spores

The muramic lactam content of spores of Bacillus sphaericus mutants defective in meso-diaminopimelic acid synthesis increases almost linearly with an increase of meso-diaminopimelic acid concentration in the medium. Since muramic lactam content is a measure of cortex content, the amount of cortex in spores of the mutants can be easily varied by changing the meso-diaminopimelic acid concentration in the medium. Characteristic properties were tested in spores containing different amounts of cortex. Critical amounts of cortex were associated with different spore properties. Refractility and dipicolinic acid accumulation in the spores both required about 20% of the maximum cortex content (although refractility is independent of dipicolinic acid content). For xylene octanol resistance, about 25% of the maximum cortex content was required.

Adenohypophysial corticotrophin and plasma free corticosteroids during regeneration of the enucleated rat adrenal gland.

From planimetric measurements of the total gland and its components, at progressively later intervals following unilateral adrenalectomy and contralateral enucleation in the rat, full regeneration of the cortex was observed to occur within 6–8 weeks. Free corticosteroids disappeared from the plasma within 6–8 hours of the enucleation procedure. Their subsequent rise, already detectable on the 4th day, culminated in a transient and slightly supernormal peak on the 16th day. From a correlation of the plasma free corticosteroid levels to the corresponding amounts of cortex, the secretory activity of the regenerating gland per unit of cortical tissue was estimated at 570% of the paired-weight control base line after 16 days, and at slightly above 200% after 7 weeks, when it leveled off. The pituitary ACTH response to the procedure was characterized by a transient rise within the first 15 minutes, followed by a fall to 35% of the control level after 4 hours, and to 22% after 12, subsequent rise to a crest of 330% on the 16th day, and regression thereafter to near-normal values, recorded on the 184th day. The concomitant rises and falls of pituitary ACTH, cortical secretory index and plasma free corticosteroids, observed in association with cortical deficiency and regeneration, reinforce the conclusion, reached from previous studies, that both release and synthesis of ACTH are accelerated by hypo- and depressed by hypercorticoidism, and that, furthermore, the regulatory effect of steroids is predominantly exerted on synthesis.

THE EFFECT OF THE ADMINISTRATION OF CARBON TETRACHLORIDE ON THE EXTENT OF REGENERATION IN THE ENUCLEATED ADRENAL GLAND OF THE RAT

Enucleation of the adrenal gland of white rats consists of excising the anterior tip of the gland and gently expressing the entire medulla and most of the cortex. The blood supply to the gland is thereby not disturbed, and the capsule and small amounts of glomerular cortex remain in situ. Regeneration of cortical tissue proceeds from the capsule and remnant of zona glomerulosa, and within short periods a volume of cortex equal to, or greater than, that of the original gland will be restored. We recently have shown that the extent of regeneration which occurs in an enucleated gland depends upon the amount of cortical tissue which is present in the body (1). In the presence of one normal gland, only slight amounts of cortex will regenerate in the other enucleated gland. If the normal gland was removed eight weeks after the enucleation of its mate, then regeneration in the hitherto inactive enucleated gland occurred rapidly.

The Relative Amounts of Grey and White Matter in some Normal and Pathological Brains.

The marked complexity of the convolutions of the brain of man, as compared with the lower animals, has suggested to numerous writers that the higher intellectual and other mental faculties characteristic of the human subject are in more or less direct relationship to the amount of grey matter in the brain. Attempts have therefore been made to measure the amount of grey matter in the brains of persons of very different degrees of intelligence and mental development. Owing to the highly complicated nature of the convolutions of the human brain, the method of estimation by direct dissection of the grey matter from the underlying white matter has not been adopted except in the case of a very few brains, most workers having approached the subject by indirect methods. Some observers have directed their attention to the measurement of the surface area of the grey matter, others to the determination of the absolute amount of cortex. Danilewsky, as a result of observations upon the specific gravity of the brain and of the grey and white matter, has calculated that the cortex forms 30 per cent. of the total brain weight. Donaldson, on the other hand, has estimated the grey matter of the hemisphere as forming 50 per cent. of the whole.