57 research outputs found
Spatial Stereoresolution for Depth Corrugations May Be Set in Primary Visual Cortex
Stereo â3Dâ depth perception requires the visual system to extract binocular disparities between the two eyes' images. Several current models of this process, based on the known physiology of primary visual cortex (V1), do this by computing a piecewise-frontoparallel local cross-correlation between the left and right eye's images. The size of the âwindowâ within which detectors examine the local cross-correlation corresponds to the receptive field size of V1 neurons. This basic model has successfully captured many aspects of human depth perception. In particular, it accounts for the low human stereoresolution for sinusoidal depth corrugations, suggesting that the limit on stereoresolution may be set in primary visual cortex. An important feature of the model, reflecting a key property of V1 neurons, is that the initial disparity encoding is performed by detectors tuned to locally uniform patches of disparity. Such detectors respond better to square-wave depth corrugations, since these are locally flat, than to sinusoidal corrugations which are slanted almost everywhere. Consequently, for any given window size, current models predict better performance for square-wave disparity corrugations than for sine-wave corrugations at high amplitudes. We have recently shown that this prediction is not borne out: humans perform no better with square-wave than with sine-wave corrugations, even at high amplitudes. The failure of this prediction raised the question of whether stereoresolution may actually be set at later stages of cortical processing, perhaps involving neurons tuned to disparity slant or curvature. Here we extend the local cross-correlation model to include existing physiological and psychophysical evidence indicating that larger disparities are detected by neurons with larger receptive fields (a size/disparity correlation). We show that this simple modification succeeds in reconciling the model with human results, confirming that stereoresolution for disparity gratings may indeed be limited by the size of receptive fields in primary visual cortex
Mobilization of healthy donors with plerixafor affects the cellular composition of T-cell receptor (TCR)-αÎČ/CD19-depleted haploidentical stem cell grafts
Background: HLA-haploidentical hematopoietic stem cell transplantation (HSCT) is suitable for patients lacking related or unrelated HLA-matched donors. Herein, we investigated whether plerixafor (MZ), as an adjunct to G-CSF, facilitated the collection of mega-doses of hematopoietic stem cells (HSC) for TCR-αÎČ/CD19-depleted haploidentical HSCT, and how this agent affects the cellular graft composition. Methods: Ninety healthy donors were evaluated. Single-dose MZ was given to 30 âpoor mobilizersâ (PM) failing to attain â„40 CD34+ HSCs/ÎŒL after 4 daily G-CSF doses and/or with predicted apheresis yields â€12.0x106 CD34+ cells/kg recipientâs body weight. Results: MZ significantly increased CD34+ counts in PM. NaĂŻve/memory T and B cells, as well as natural killer (NK) cells, myeloid/plasmacytoid dendritic cells (DCs), were unchanged compared with baseline. MZ did not further promote the G-CSF-induced mobilization of CD16+ monocytes and the down-regulation of IFN-Îł production by T cells. HSC grafts harvested after G-CSF + MZ were enriched in myeloid and plasmacytoid DCs, but contained low numbers of pro-inflammatory 6-sulfo-LacNAc+ (Slan)-DCs. Finally, children transplanted with G-CSF + MZ-mobilized grafts received greater numbers of monocytes, myeloid and plasmacytoid DCs, but lower numbers of NK cells, NK-like T cells and Slan-DCs. Conclusions: MZ facilitates the collection of mega-doses of CD34+ HSCs for haploidentical HSCT, while affecting graft composition
Variation in dopamine D2 and serotonin 5-HT2A receptor genes is associated with working memory processing and response to treatment with antipsychotics
Dopamine D2 and serotonin 5-HT2A receptors contribute to modulate prefrontal cortical physiology and response to treatment with
antipsychotics in schizophrenia. Similarly, functional variation in the genes encoding these receptors is also associated with these
phenotypes. In particular, the DRD2 rs1076560 T allele predicts a lower ratio of expression of D2 short/long isoforms, suboptimal
working memory processing, and better response to antipsychotic treatment compared with the G allele. Furthermore, the HTR2A T
allele is associated with lower 5-HT2A expression, impaired working memory processing, and poorer response to antipsychotics
compared with the C allele. Here, we investigated in healthy subjects whether these functional polymorphisms have a combined effect
on prefrontal cortical physiology and related cognitive behavior linked to schizophrenia as well as on response to treatment with secondgeneration
antipsychotics in patients with schizophrenia. In a total sample of 620 healthy subjects, we found that subjects with the
rs1076560 T and rs6314 T alleles have greater fMRI prefrontal activity during working memory. Similar results were obtained within the
attentional domain. Also, the concomitant presence of the rs1076560 T/rs6314 T alleles also predicted lower behavioral accuracy during
working memory. Moreover, we found that rs1076560 T carrier/rs6314 CC individuals had better responses to antipsychotic treatment
in two independent samples of patients with schizophrenia (nŒ63 and nŒ54, respectively), consistent with the previously reported
separate effects of these genotypes. These results indicate that DRD2 and HTR2A genetic variants together modulate physiological
prefrontal efficiency during working memory and also modulate the response to antipsychotics. Therefore, these results suggest that
further exploration is needed to better understand the clinical consequences of these genotypeâphenotype relationships
Multimodal population brain imaging in the UK Biobank prospective epidemiological study
Medical imaging has enormous potential for early disease prediction, but is impeded by the difficulty and expense of acquiring data sets before symptom onset. UK Biobank aims to address this problem directly by acquiring high-quality, consistently acquired imaging data from 100,000 predominantly healthy participants, with health outcomes being tracked over the coming decades. The brain imaging includes structural, diffusion and functional modalities. Along with body and cardiac imaging, genetics, lifestyle measures, biological phenotyping and health records, this imaging is expected to enable discovery of imaging markers of a broad range of diseases at their earliest stages, as well as provide unique insight into disease mechanisms. We describe UK Biobank brain imaging and present results derived from the first 5,000 participants' data release. Although this covers just 5% of the ultimate cohort, it has already yielded a rich range of associations between brain imaging and other measures collected by UK Biobank
Pediatric multiple sclerosis: update on diagnostic criteria, imaging, histopathology and treatment choices
Pediatric multiple sclerosis (MS) represents less than 5% of the MS population, but patients with pediatric-onset disease reach permanent disability at a younger age than adult onset patients. Accurate diagnosis at presentation and optimal long-term treatment is vital to mitigate ongoing neuroinflammation and irreversible neurodegeneration.
However, it may be difficult to early differentiate pediatric MS from acute disseminated
encephalomyelitis (ADEM) and neuromyelitis optica spectrum disorders (NMOSD) as they often have atypical presentation that differs from that of adult-onset MS. The
purpose of this review is to summarize the updated views on diagnostic criteria, imaging, histopathology and treatment choices
Certify or not? An analysis of organic food supply chain with competing suppliers
Customers expect companies to provide clear health-related information for the products they purchase in a big data environment. Organic food is data-enabled with the organic label, but the certification cost discourages small-scale suppliers from certifying their product. This lack of a label means that product that satisfies the organic standard is regarded as conventional product. By considering the trade-off between the profit gained from organic label and additional costs of certification, this paper investigates an organic food supply chain where a leading retailer procures from two suppliers with different brands. Customers care about both the brand-value and quality (more specifically, if food is organic or not) when purchasing the product. We explore the organic certification and wholesale pricing strategies for suppliers, and the supplier selection and retail pricing strategies for the retailer. We find that when two suppliers adopt asymmetric certification strategy, the retailer tends to procure the product with organic label. The supplier without a brand name can compensate with organic certification, which leads to more profits than the branded rival. As the risk of being abandoned by the retailer increases, the supplier without a brand name is more eager than the rival to obtain the organic label. If both suppliers certify the product, however, they will fall into a prisonerâs dilemma under situation with low health utility from organic label and high certification cost
Influence of fertilization on the growth of radicchio "Rosso di Chioggia" cultivated in two different environments
This study evaluated the influence of fertilization on some growth
indexes in radicchio "Rosso di Chioggia". The trial was conducted in
Rovigo (Italy) for two years and in Mendoza (Argentina) for one year.
Increasing doses of macronutrients were considered, identified as
N0P0K0, N1P1K1, N2P2K2 and, only in Rovigo, N3P2K2. Some indexes related
to growth analysis: relative growth rate (RGR), net assimilation rate
(NAR), leaf area ratio (LAR), specific leaf area (SLA), leaf weigh ratio
(LWR), crop growth ratio (CGR), leaf area index (LAI) and leaf area
duration (LAD) were calculated during the growing cycle. At Mendoza CGR
was strongly influenced by NAR from transplant until 776 growth degree
days (ODD). After that moment, CGR was affected by LAI that increased
markedly due to favourable environmental conditions. From 1052 to 1653
GDD the high increase of LAI determined a reduction in photosynthetic
efficiency. At Rovigo the trends in index values showed differences
between the two years considered, especially in LAR and SLA. In the
second year CGR had always higher values; mainly due to higher LAI
values, since NAR did not differ significantly during the years. In the
second half of the growing cycle, CGR was instead strongly linked to a
contraction of photosynthetic effectiveness, due to head formation. High
LAI values showed a growing cycle extension to the detriment of early
head formation. It was also observed that when LWR is around 0.35 - 0.40
g g(-1), the plant reaches marketable maturation and is ready to be
harvested. In both environments, no clear effects of fertilization were
observed on the growth indexes. In any case highly fertilized plants
showed higher growing activity especially at the beginning of the
growing cycle
The organization of dorsal frontal cortex in humans and macaques.
The human dorsal frontal cortex has been associated with the most sophisticated aspects of cognition, including those that are thought to be especially refined in humans. Here we used diffusion-weighted magnetic resonance imaging (DW-MRI) and functional MRI (fMRI) in humans and macaques to infer and compare the organization of dorsal frontal cortex in the two species. Using DW-MRI tractography-based parcellation, we identified 10 dorsal frontal regions lying between the human inferior frontal sulcus and cingulate cortex. Patterns of functional coupling between each area and the rest of the brain were then estimated with fMRI and compared with functional coupling patterns in macaques. Areas in human medial frontal cortex, including areas associated with high-level social cognitive processes such as theory of mind, showed a surprising degree of similarity in their functional coupling patterns with the frontal pole, medial prefrontal, and dorsal prefrontal convexity in the macaque. We failed to find evidence for "new" regions in human medial frontal cortex. On the lateral surface, comparison of functional coupling patterns suggested correspondences in anatomical organization distinct from those that are widely assumed. A human region sometimes referred to as lateral frontal pole more closely resembled area 46, rather than the frontal pole, of the macaque. Overall the pattern of results suggest important similarities in frontal cortex organization in humans and other primates, even in the case of regions thought to carry out uniquely human functions. The patterns of interspecies correspondences are not, however, always those that are widely assumed
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Pre-flight integration and characterization of the SPIDER balloon-borne telescope
We present the results of integration and characterization of the Spider instrument after the 2013 pre-flight campaign. SPIDER is a balloon-borne polarimeter designed to probe the primordial gravitational wave signal in the degree-scale B-mode polarization of the cosmic microwave background. With six independent telescopes housing over 2000 detectors in the 94 GHz and 150 GHz frequency bands, SPIDER will map 7.5% of the sky with a depth of 11 to 14 mu K.arcmin at each frequency, which is a factor of similar to 5 improvement over Planck. We discuss the integration of the pointing, cryogenic, electronics, and power sub-systems, as well as pre-flight characterization of the detectors and optical systems. SPIDER is well prepared for a December 2014 flight from Antarctica, and is expected to be limited by astrophysical foreground emission, and not instrumental sensitivity, over the survey region
Organogenesis from shoot segments and via callus of endangered Kosteletzkya pentacarpos (L.) Ledeb.
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