Changes In Deep Layers Research Articles

Parvalbumin interneuron activity induces slow cerebrovascular fluctuations in awake mice.

Neuronal regulation of cerebrovasculature underlies brain imaging techniques reliant on cerebral blood flow (CBF) changes. However, interpreting these signals requires understanding their neural correlates. Parvalbumin (PV) interneurons are crucial in network activity, but their impact on CBF is not fully understood. Optogenetic studies show that stimulating cortical PV interneurons induces diverse CBF responses, including rapid increases, decreases, and slower delayed increases. To clarify this relationship, we measured hemodynamic and neural responses to optogenetic stimulation of PV interneurons expressing Channelrhodopsin-2 during evoked and ongoing resting-state activity in the somatosensory cortex of awake mice. Two-photon microscopy (2P) Ca2+ imaging showed robust activation of PV-positive (PV+) cells and inhibition of PV-negative (PV-) cells. Prolonged PV+ cell stimulation led to a delayed, slow CBF increase, resembling a secondary peak in the CBF response to whisker stimulation. 2P vessel diameter measurements revealed that PV+ cell stimulation induced rapid arterial vasodilation in superficial layers and delayed vasodilation in deeper layers. Ongoing activity recordings indicated that both PV+ and PV- cell populations modulate arterial fluctuations at rest, with PV+ cells having a greater impact. These findings show that PV interneurons generate a complex depth-dependent vascular response, dominated by slow vascular changes in deeper layers.

BEHAVIOR OF THE SQUARE WAVE IN BIOLOGICAL STRUCTURES

This study is to experimentally investigate the behavior of quadratic waves in biological structures. Transcutaneous frequency stimulation was regulated so that the system provided high frequency and low electrical voltage to observe possible changes in deeper layers of the anatomical structure analyzed. Electrodes were positioned from the dermis and probing electrodes were positioned at the subdermal, intradermal, skeletal muscle, periosteum, endosteum, and medulla levels. A function generator connected to a digital oscilloscope produced a square wave of 33 kHz at 10µs pulse speed and voltage of 16 volts DC. A voltage decay was observed as the signal reached deeper layers of different tissues. However, the frequency of 33 kHz remained uniform even at the bone marrow level. This observation opens the way for the application of the square electronic frequency as a stimulus for drug activation.

Profile Soil Carbon and Nitrogen Dynamics in Typical Chernozem under Long-Term Tillage Use

For the first time in research literature, this report presents the seasonal changes of total organic carbon (TOC), total nitrogen (TN), and TOC:TN ratio in Chernozem solum (0–100 cm) as effected by 14 years of application of conventional tillage (CTu), deep reduced tillage (DRTu), and reduced tillage (RTu) under barley growing. During the season, TOC content drastically declined in the spring, increased in the summer, decreased in the middle of August, and recovered in October. TN content was gradually decreased during a crop growing season and renewed in the autumn. A trend of TOC:TN changes (vertical peak curve) in 0–30 cm soil layer varied from TOC (S-shaped curve) and TN (unsymmetrical decayed curve). The amplitude of seasonal TOC and TN changes in deeper layers was far fewer related to the upper horizons. The highest amplitude in 0–30, 30–60 and 60–100 cm layers was under: DRTu, CTu, DRTu—for TOC and DRTu, CTu, RTu—for TN correspondently. Tillage practices differently stratified the content of organic carbon and nitrogen in Chernozem profile. Minimum tillage benefited TOC sequestration in 0–5 and 5–10 cm layers: 24.83 ± 0.64- and 24.65 ± 0.57 g kg−1—under RTu, 24.49 ± 0.62- and 24.71 ± 0.47 g kg−1—under DRTu, while CT—deeper than 20 cm: 22.49–15.03 g kg−1. The vertical distribution of TN content repeated TOC trend. TOC:TN ratio upraised from 12.60 in 0–5 to 14.33 in 80–100 cm layer and was the highest in summertime. A total (0–100 cm) profile was much greater under RTu and DRTu—for TN, and CTu, DRTu—for TOC. The correlation coefficient (r) was almost negligible between TOC and: T (air temperature), P (precipitation) and W (soil moisture). The strong and very strong r was found for TN—W, and P—W pairs. The negative r was between: TOC–P, TN–P, TOC:TN-W, TOC:TN–T and P–W pairs.

Fine-root dynamics vary with soil depth and precipitation in a low-nutrient tropical forest in the Central Amazonia.

A common assumption in tropical ecology is that root systems respond rapidly to climatic cues but that most of that response is limited to the uppermost layer of the soil, with relatively limited changes in deeper layers. However, this assumption has not been tested directly, preventing models from accurately predicting the response of tropical forests to environmental change.We measured seasonal dynamics of fine roots in an upper-slope plateau in Central Amazonia mature forest using minirhizotrons to 90cm depth, which were calibrated with fine roots extracted from soil cores.Root productivity and mortality in surface soil layers were positively correlated with precipitation, whereas root standing length was greater during the dry periods at the deeper layers. Contrary to historical assumptions, a large fraction of fine-root standing biomass (46%) and productivity (41%) was found in soil layers deeper than 30cm. Furthermore, root turnover decreased linearly with soil depth.Our findings demonstrate a relationship between fine-root dynamics and precipitation regimes in Central Amazonia. Our results also emphasize the importance of deeper roots for accurate estimates of primary productivity and the interaction between roots and carbon, water, and nutrients.

Monte-Carlo Simulation of Light Tissue Interaction in Medical Hyperspectral Imaging Applications

Abstract In Hyperspectral imaging (HSI) applications in medicine a uniform illumination is used and the illuminated surface is recorded with a camera with spectral resolution. Unlike in tissue reflectance spectroscopy with fixed light source - detector distances, in HSI the contribution of the influence of different tissue layers to the absorption signal is poorly understood. In this work a Monte-Carlo simulation is implemented which simulates the specific HSI illumination and detector geometry. A four-layer tissue model with variable blood volume fraction and oxygen saturation is used. With 5 % blood volume fraction and 75 % oxygen saturation, SaO2, of surrounding tissue, saturation changes in 1 mm and 2 mm deep layers lead to a change in remission of up to 3 % and up to 1 % respectively. Changes in deeper layers are hardly detectable. Further simulations will be focused on different tissue models as the depth resolution is expected to vary with tissue parameters like blood volume fraction.

Genetic Mapping in Mice Reveals the Involvement of Pcdh9 in Long-Term Social and Object Recognition and Sensorimotor Development

BackgroundQuantitative genetic analysis of basic mouse behaviors is a powerful tool to identify novel genetic phenotypes contributing to neurobehavioral disorders. Here, we analyzed genetic contributions to single-trial, long-term social and nonsocial recognition and subsequently studied the functional impact of an identified candidate gene on behavioral development. MethodsGenetic mapping of single-trial social recognition was performed in chromosome substitution strains, a sophisticated tool for detecting quantitative trait loci (QTL) of complex traits. Follow-up occurred by generating and testing knockout (KO) mice of a selected QTL candidate gene. Functional characterization of these mice was performed through behavioral and neurological assessments across developmental stages and analyses of gene expression and brain morphology. ResultsChromosome substitution strain 14 mapping studies revealed an overlapping QTL related to long-term social and object recognition harboring Pcdh9, a cell-adhesion gene previously associated with autism spectrum disorder. Specific long-term social and object recognition deficits were confirmed in homozygous (KO) Pcdh9-deficient mice, while heterozygous mice only showed long-term social recognition impairment. The recognition deficits in KO mice were not associated with alterations in perception, multi-trial discrimination learning, sociability, behavioral flexibility, or fear memory. Rather, KO mice showed additional impairments in sensorimotor development reflected by early touch-evoked biting, rotarod performance, and sensory gating deficits. This profile emerged with structural changes in deep layers of sensory cortices, where Pcdh9 is selectively expressed. ConclusionsThis behavior-to-gene study implicates Pcdh9 in cognitive functions required for long-term social and nonsocial recognition. This role is supported by the involvement of Pcdh9 in sensory cortex development and sensorimotor phenotypes.

Changes in soil organic carbon, nitrogen, pH and bulk density with the development of larch (Larix gmelinii) plantations in China

Under the government of China's environmental program known as Returning Farmland To Forests (RFTF), about 28 million hectares of farmland have been converted to tree plantation. This has led to a large accumulation of biomass carbon, but less is known about underground carbon-related processes. One permanent plot (25 years of observation) and four chronosequence plot series comprising 159 plots of larch (Larix gmelinii) plantations in northeastern China were studied. Both methods found significant soil organic carbon (SOC) accumulation (96.4 g C m−2 yr−1) and bulk density decrease (5.7 mg cm−3 yr−1) in the surface soil layer (0–20 cm), but no consistent changes in deeper layers, indicating that larch planting under the RFTF program can increase SOC storage and improve the physical properties of surface soil. Nitrogen depletion (4.1–4.3 g m−2 yr−1), soil acidification (0.007–0.022 pH units yr−1) and carbon/nitrogen (C/N) ratio increase (0.16–0.46 per year) were observed in lessive soil, whereas no significant changes were found in typical dark-brown forest soil. This SOC accumulation rate (96.4 g m−2 yr−1) can take 39% of the total carbon sink capacity [net ecosystem exchange (NEE)] of larch forests in this region and the total soil carbon sequestration could be 87 Tg carbon within 20 years of plantation by approximating all larch plantations in northeastern China (4.5 Mha), showing the importance of soil carbon accumulation in the ecosystem carbon balance. By comparison with the rates of these processes in agricultural use, the RFTF program of reversing land use for agriculture will rehabilitate SOC, soil fertility and bulk density slowly (< 69% of the depletion rate in agricultural use), so that a much longer duration is needed to rehabilitate the underground function of soil via the RFTF program. Global forest plantations on abandoned farmland or function to protecting farmland are of steady growth and our findings may be important for understanding their underground carbon processes.

Interactions between liposomes and human stratum corneum in vitro: freeze fracture electron microscopical visualization and small angle X-ray scattering studies.

The interactions between three liposomal formulations and human stratum corneum were visualized using freeze fracture electron microscopy. A new replica cleaning method was introduced. Human stratum corneum was submerged for 48 h in liposome suspensions prepared from commercially available phospholipid mixtures. The size, lamellarity and lipid moieties of the liposomes were similar. The main difference between the three phospholipid formulations was the hydrophilicity of the headgroups. The composition dependence of the interactions between these vesicles and human stratum corneum was investigated. In essence, two types of interaction were observed: adsorption of the liposomes on to the outer surface of the stratum corneum, and ultrastructural changes in deeper layers of the stratum corneum caused by mixing of the liposomal constituents and the stratum corneum lipids. The electron microscopic observations were verified with small-angle X-ray scattering. It was found that liposomes composed of phospholipids containing relatively small hydrophilic headgroups showed a marked interaction with the skin lipids of human stratum corneum in vitro. The complexity of the phospholipid mixtures, however, made it very difficult to determine the exact effect each of these headgroups has on the interactions between these vesicles and human stratum corneum.

PANCREATIC HETEROTOPIA AND CYSTIC DYSTROPHY OF DUODENUM, AN UNCOMMON PATHOLOGY AND THE ROLE OF ENDOSCOPIC ULTRASOUND IN THE DIAGNOSIS

Pancreatic heterotopy, a rare entity, is defined as pancreatic tissue lying outside its normal location without anatomical or vascular connections with the pancreas proper. Cystic dystrophy is an uncommon and serious complication of heterotopic pancreas, usually in younger men. The mechanism by which cystic dystrophy develops is poorly understood. It is difficult to diagnose, as lesions deeper in the submucosa or the muscularis propria, are difficult to biopsy. We present an interesting and rare case of pancreatic heterotopia with cystic dystrophy of the duodenal wall, where endoscopic ultrasound clearly shows cystic changes in deeper layers of duodenum, later confirmed by surgery. Case: A 54-yr-old white male presented to the hospital after several bouts of abdominal pain. Prior to presentation, he experienced several episodes of nausea and vomiting. He also had lost approximately 15 lb over the past two months. Past history was significant for non-hodgkins lymphoma, which had been in remission for 6 years. During endoscopy, a sessile mucosal lesion with mass effect was visualized in the second part of the duodenum and biopsies were obtained. Pathology was negative for cancer, but did show edema and lymphangiectasia. Endoscopic ultrasound showed a 1 cm cystic lesion in the wall of duodenum at the second portion. A pancreas-preserving duodenectomy was performed. Duodenal specimens showed a cystic lesion in the wall of duodenum. The mucosa overlying the cyst showed a mix of acute and chronic inflammation of the lamiNaPropria. The cyst was located within the muscularis propria, which was hypertrophied. Focal areas showed an epithelial lining composed of columnar/cuboidal cells with basal nuclei and prominent brush border, suggestive of pancreatic ductal epithelium. Based on these findings, a diagnosis of heterotopic pancreas with cystic dystrophy of the duodenal wall was made. Discussion: Duodenal cystic dystrophy due to heterotopic pancreatic deposit is an uncommon pathology. In the past, it was extremely difficult to diagnose without surgery because there are no specific clinical signs. Our case demonstrates effective use of endoscopic ultrasound in precisely locating cysts in the duodenal wall when other imaging modalities, such as CT scan can not. We will present EUS images, histology slides and a detail discussion about heterotopic pancreatic cyst and the role of different diagnostic modalities.

The “peeling” method to process apparent resistivity data for earthquake precursory monitoring

Considering the fact that there is only one pair of fixed potential poles in one direction used to monitor the resistivity changes under the observatory station which may indicate process of earthquake preparation, based on the precondition that the resistivity structure is 1-dimensional under the observatory station, and by way of equivalent model put forward by the authors, this paper suggests a kind of method trying to separate the resistivity changes in deep layers from that of the shallow layer. Analysis shows that, to obtain the same measured data with the same array, any a multi-layered geo-electrical structure can be equivalently taken as a two-layered one, we call it equivalent model. In this paper, the resistivity and thickness of the upper layer of the equivalent model are equal to that of the first layer of the original one, the resistivity of the lower layer of the equivalent model is obtained with calculation according to the requirement of equivalence, its value is relevant with the resistivities and thicknesses of all layer of the original model except for the first one, so the resistivity change of the equivalent layer can indicate the synthetic effect of variation of all layers of the original model except for the first one. The primary research results show that this method can work well.

Infrared scanning laser tomography of macular cysts

ObjectiveTo perform three-dimensional, noninvasive, quantitative analysis of cystoid macular edema and macular cysts using infrared scanning laser tomography and to correlate findings with visual acuity (VA) as a basis for interventional studies. DesignCross-sectional, nonrandomized study. ParticipantsSeventeen patients (29–86 years of age) with macular cysts associated with a broad spectrum of diseases. InterventionConfocal infrared imaging with scanning laser tomography with the TopSS (790 nm) (Laser Diagnostic Technologies, San Diego, CA) with digitized images was used to perform three-dimensional, quantitative analysis of cysts in the central 5° of the macula. Main outcome measuresMeasurements of macular cyst number, area, volume, depth, slope, height of the surrounding macular elevation, and correlation with VA. ResultsScanning laser tomography detected macular cysts in all patients. The number per patient ranged from 1 through 15. Cysts were accompanied by surrounding macular elevation in 16 patients (mean macular height, 216 μm). The area covered by cysts in the central 5° was 0.087 to 0.969 mm2, and volume was 0.007 to 0.549 mm3. Visual acuity was significantly poorer in patients with greater cyst area (P = 0.0007), cyst volume (P = 0.0009), macular thickening (P = 0.0002), and cyst depth (P = 0.0013). Cyst number, average slope, and maximum slope, however, did not correlate significantly with VA. Grouping of macular cysts according to macular height and average cyst depth revealed that cysts in a more thickened retina were significantly deeper, had steeper slopes, and corresponded to worse VA. Macular height and average cyst depth were highly associated with each other, suggesting that in eyes with surrounding macular edema, cysts were deeper and may reflect more widespread tissue destruction. Individual confocal tomographic images provided additional information. Neither ophthalmoscopy nor fluorescein angiography delineated features such as retinal folds that suggested vitreous traction or changes in deeper layers that suggested occult choroidal new vessels. ConclusionsInfrared scanning laser tomography is a rapid and noninvasive imaging method that provides quantitative analysis of macular cysts in addition to qualitative information not seen clinically. Because poor VA is related to severe involvement of the central retina, scanning laser tomography could provide an objective outcome measure for interventional studies.

Rapid Changes of Optical Parameters in the Human Brain During a Tapping Task

Measures of parameters of the migration of near-infrared photons through the head (attenuation, or intensity, and time-of-flight, or delay) have been proposed as a way of assessing noninvasively and in a quasicontinuous fashion changes in the scattering and absorption properties of brain tissue. These, in turn, may reflect functional changes associated with behavioral tasks. To test this hypothesis, we measured changes of photon migration parameters from scalp locations proximal to the motor cortex from four human subjects, tapping at a rate of 0.8 Hz with their left or right hand, or with their left or right foot. Tapping produced both slow effects (requiring several seconds) and fast effects (tracking the tapping frequency). Slow effects were characterized by increase and delay of the light passing through the hemisphere contralateral to the tapping hand. Fast effects consisted of changes in the light delay during hand tapping. Monte Carlo simulations based on layer models of the brain indicated that fast effects are consistent with changes in deep layers of the head (presumably in the cortex), and that slow effects are consistent with either a shift of absorbing material toward deeper layers or a reduction in scattering. These results suggest that optical parameters can monitor rapid changes of brain activity, matching the contralateral organization of the motor cortex.

Development of rat visual system after prenatal X-irradiation

Summary Rats pregnant for 16 or 19 days (ED 16 or 19) were irradiated with 100 r and killed after 24 hrs or at age 24 or 180 days. The primary influence of X-rays consists in a lethal lesion of cells located in the periventricular zone as well as some of the more differentiated cells in the brain parenchyma. After irradiation on ED 16, the acute damage was greater in the cerebral cortex and the superior colliculus (SC) than in the lateral geniculate nucleus (LGN). Irradiation on ED 19 damaged mainly the cortical part of the visual system. The degree of acute damage is therefore inversely proportional to the degree of histo- and cytodifferentiation of the visual centres (Bruckner et ai. 1976). In adult animals the acute radiation damage results in a deficit in packing density and the total number of neurons. Animals irradiated on ED 16 revealed more pronounced changes in deep layers of the cortex (L VI) than in the superficial layers. The deficit was smaller in the SC, and in the LGN an increase in the packing density of nerve cells was found. In animals irradiated on ED 19, the deficit in neurons density occurred mainly in more superficial layers of the cortex, with a maximum deficit in layer IV. From comparison of acute and final changes it may be concluded that the damage of preneuroblastic cell populations is compensated during later embryonic development, while the damage induced in populations already at early neuroblast stage is irreversible and leads to a permanent deficit. Glia cell population is altered in a similar way as the number of neurons in regions poor in myelin, while in regions rich in myelin the number of glia cells seems to depend on changes in the number of efferent and afferent nerve fibres.

Predicting Soil Moisture in the Southern Appalachians

AbstractSoil moisture was measured for 3.5 years on forested slopes in the mountains of western North Carolina to develop equations for predicting soil moisture content of watersheds. Predictors used were precipitation and easily measured topographic, seasonal, and soil physical factors; among these, sand content and moisture retention at 1‐bar suction were the best predictors of moisture content. Position on slope (height or distance from the stream channel) appeared to be an important factor only in the lower 25% of the slope. The annual cycle of soil moisture in the top 213 cm approximated a sine wave with a maximum during mid‐April and a minimum during mid‐October. As expected, moisture changes in surface layers were correlated best with rainfall weighted toward days immediately preceding observation; changes in deeper layers were better correlated with rainfall during previous weeks. Seasonal changes in soil moisture content at all depths were greatest upslope and least in the lower slope. Equations developed account for about 88% of the variation in soil moisture (standard error approximately 2–3% by volume) and can be used to predict antecedent moisture distribution for hydrologic and other purposes. Results support the “variable source area” concept of streamflow, but even with the neutron method slope gradients in field moisture were not easy to detect.