Human visual processing of orientation in broad stimuli.

Recently our lab has shown that with broadband stimuli (either visual noise or natural scenes), performance for detecting oriented content is worst at horizontal, best at the obliques, and intermediate at vertical orientations--an anisotropy (termed the horizontal effect ) quite different from the well-known oblique effect (worst performance obliques) obtained with simple line or grating stimuli. This horizontal effect can be explained by a proposed anisotropic normalization model that operates at the level of striate cortex by implementing the known numerical biases of striate neurons preferring different orientations as well as the strength of those responses from neurons tuned to similar orientations and spatial frequencies (with that strength being dependent on the spatial relationships between different scales and orientations present in the stimuli). To assess how the proposed striate normalization mechanism might operate when the visual system is presented with broadband stimuli containing different amounts of spatial frequency and orientation content, two suprathreshold matching experiments were conducted. Additionally, to provide an estimate of how broadband stimuli might modulate the weights of the proposed model, a series of neural response simulations were carried out on different types of broadband natural scene imagery. The stimuli for the psychophysical experiments were generated by making broadband isotropic visual noise patterns and filtering their amplitude spectra to contain a test increment across a specified range of orientations and spatial frequencies. The extent of the test increment\u27s orientation and frequency bandwidth was systematically varied. A standard psychophysical matching paradigm was used to assess the perceived strength of the oriented structure in a test pattern relative to the oriented structure in a comparison pattern. The results yielded the traditional oblique effect when a fairly small range of orientations and high spatial frequencies were incremented and the horizontal effect was observed for broadband increments of about 20 degrees and 1-octave in frequency and larger. A blend of the two anisotropies was observed at intermediate increment bandwidth. The results of the psychophysical experiments were discussed in the context of the proposed striate normalization model with added insight from the results of the neural response simulations

Disentangling the Independent Contributions of Visual and Conceptual Features to the Spatiotemporal Dynamics of Scene Categorization

Human scene categorization is characterized by its remarkable speed. While many visual and conceptual features have been linked to this ability, significant correlations exist between feature spaces, impeding our ability to determine their relative contributions to scene categorization. Here, we used a whitening transformation to decorrelate a variety of visual and conceptual features and assess the time course of their unique contributions to scene categorization. Participants (both sexes) viewed 2250 full-color scene images drawn from 30 different scene categories while having their brain activity measured through 256-channel EEG. We examined the variance explained at each electrode and time point of visual event-related potential (vERP) data from nine different whitened encoding models. These ranged from low-level features obtained from filter outputs to high-level conceptual features requiring human annotation. The amount of category information in the vERPs was assessed through multivariate decoding methods. Behavioral similarity measures were obtained in separate crowdsourced experiments. We found that all nine models together contributed 78% of the variance of human scene similarity assessments and were within the noise ceiling of the vERP data. Low-level models explained earlier vERP variability (88 ms after image onset), whereas high-level models explained later variance (169 ms). Critically, only high-level models shared vERP variability with behavior. Together, these results suggest that scene categorization is primarily a high-level process, but reliant on previously extracted low-level features

Dynamic Electrode-to-Image (DETI) mapping reveals the human brain’s spatiotemporal code of visual information

A number of neuroimaging techniques have been employed to understand how visual information is transformed along the visual pathway. Although each technique has spatial and temporal limitations, they can each provide important insights into the visual code. While the BOLD signal of fMRI can be quite informative, the visual code is not static and this can be obscured by fMRI’s poor temporal resolution. In this study, we leveraged the high temporal resolution of EEG to develop an encoding technique based on the distribution of responses generated by a population of real-world scenes. This approach maps neural signals to each pixel within a given image and reveals location-specific transformations of the visual code, providing a spatiotemporal signature for the image at each electrode. Our analyses of the mapping results revealed that scenes undergo a series of nonuniform transformations that prioritize different spatial frequencies at different regions of scenes over time. This mapping technique offers a potential avenue for future studies to explore how dynamic feedforward and recurrent processes inform and refine high-level representations of our visual world

The Effects of tDCS Across the Spatial Frequencies and Orientations that Comprise the Contrast Sensitivity Function

Richard B, Johnson AP, Thompson B and Hansen BC (2015) The Effects of tDCS Across the Spatial Frequencies and Orientations that Comprise the Contrast Sensitivity Function. Front. Psychol. 6:1784. doi: 10.3389/fpsyg.2015.01784Transcranial Direct Current Stimulation (tDCS) has recently been employed in traditional psychophysical paradigms in an effort to measure direct manipulations on spatial frequency channel operations in the early visual system. However, the effects of tDCS on contrast sensitivity have only been measured at a single spatial frequency and orientation. Since contrast sensitivity is known to depend on spatial frequency and orientation, we ask how the effects of anodal and cathodal tDCS may vary according to these dimensions. We measured contrast sensitivity with sinusoidal gratings at four different spatial frequencies (0.5, 4, 8, and 12 cycles/°), two orientations (45° Oblique and Horizontal), and for two stimulus size conditions [fixed size (3°) and fixed period (1.5 cycles)]. Only contrast sensitivity measured with a 45° oblique grating with a spatial frequency of 8 cycles/° (period = 1.5 cycles) demonstrated clear polarity specific effects of tDCS, whereby cathodal tDCS increased and anodal tDCS decreased contrast sensitivity. Overall, effects of tDCS were largest for oblique stimuli presented at high spatial frequencies (i.e., 8 and 12 cycles/°), and were small or absent at lower spatial frequencies, other orientations and stimulus size. Thus, the impact of tDCS on contrast sensitivity, and therefore on spatial frequency channel operations, is opposite in direction to other behavioral effects of tDCS, and only measurable in stimuli that generally elicit lower contrast sensitivity (e.g., oblique gratings with period of 1.5 cycles at spatial frequencies above the peak of the contrast sensitivity function).Portions of the current study were funded by a discovery grant from the Natural Sciences and Engineering Research Council (NSERC) to AJ, and by the Colgate Research Council Grant to BH. BR was supported by the Fonds de Recherche du Quebec – Nature et Technologie (FQRNT), and a bursary from the Ministère de l’Éducation, de l’Enseignement supérieur et de la Recherche (MEESR)

Towards a state-space geometry of neural responses to natural scenes: A steady-state approach

Our understanding of information processing by the mammalian visual system has come through a variety of techniques ranging from psychophysics and fMRI to single unit recording and EEG. Each technique provides unique insights into the processing framework of the early visual system. Here, we focus on the nature of the information that is carried by steady state visual evoked potentials (SSVEPs). To study the information provided by SSVEPs, we presented human participants with a population of natural scenes and measured the relative SSVEP response. Rather than focus on particular features of this signal, we focused on the full state-space of possible responses and investigated how the evoked responses are mapped onto this space. Our results show that it is possible to map the relatively high-dimensional signal carried by SSVEPs onto a 2-dimensional space with little loss. We also show that a simple biologically plausible model can account for a high proportion of the explainable variance (~73%) in that space. Finally, we describe a technique for measuring the mutual information that is available about images from SSVEPs. The techniques introduced here represent a new approach to understanding the nature of the information carried by SSVEPs. Crucially, this approach is general and can provide a means of comparing results across different neural recording methods. Altogether, our study sheds light on the encoding principles of early vision and provides a much needed reference point for understanding subsequent transformations of the early visual response space to deeper knowledge structures that link different visual environments

The New Political Economy of EU State Aid Policy

Despite its importance and singularity, the EU’s state aid policy has attracted less scholarly attention than other elements of EU competition policy. Introducing the themes addressed by the special issue, this article briefly reviews the development of EU policy and highlights why the control of state aid matters. The Commission’s response to the current economic crisis notably in banking and the car industry is a key concern, but the interests of the special issue go far beyond. They include: the role of the European Commission in the development of EU policy, the politics of state aid, and a clash between models of capitalism. The special issue also examines the impact of EU policy. It investigates how EU state aid decisions affect not only industrial policy at the national level (and therefore at the EU level), but the welfare state and territorial relations within federal member states, the external implications of EU action and the strategies pursued by the Commission to limit any potential disadvantage to European firms, and the conflict between the EU’s expanding legal order and national

Historical and Projected Municipal and Industrial Water Usage in Utah 1960-2020

This publication reports the results of a municipal and industrial water use inventory. Data reported covers the period 1960 through 1976. Time series information is aggregated from municipal and industrial system level to country and state totals. Total municipal and industrial withdrawals are divided between surface and groundwater sources. Yearly per capital withdrawal rates are estimated for 50 Utah municipalities and for each of Utah’s 29 counties. Per capita withdrawal rates range from a high of over 400 gallons per capita per day (gcd) in the communities of Delta, Fillmore, Hyrum, Logan, and Morgan to a low of 100 gcd in Bountiful, Washington, Terrace, Centerville, and South Ogden. A three year average (1974, 1975, and 1976) of Utah’s per capita withdrawal rate is 262 gcd. Also reported are return flow rates for 13 Utah waste treatment facilities. Withdrawal and return flow rates are also reported for Utah’s major water using industries. These rates are reported in gallons per employee per day (or gallons per unit of output). The publication also discusses methodologies for projecting municipal and industrial usage in Utah to the year 2020. Also reported are population projections for multicounty districts, counties and major cities by ten year intervals from 1960-2020

Palifermin for oral mucositis after intensive therapy for hematologic cancers

BACKGROUND: Oral mucositis is a complication of intensive chemotherapy and radiotherapy with no effective treatment. We tested the ability of palifermin (recombinant human keratinocyte growth factor) to decrease oral mucosal injury induced by cytotoxic therapy. METHODS: This double-blind study compared the effect of palifermin with that of a placebo on the development of oral mucositis in 212 patients with hematologic cancers; 106 patients received palifermin (60 microg per kilogram of body weight per day) and 106 received a placebo intravenously for three consecutive days immediately before the initiation of conditioning therapy (fractionated total-body irradiation plus high-dose chemotherapy) and after autologous hematopoietic stem-cell transplantation. Oral mucositis was evaluated daily for 28 days after transplantation. RESULTS: The incidence of oral mucositis of World Health Organization (WHO) grade 3 or 4 was 63 percent in the palifermin group and 98 percent in the placebo group (P\u3c0.001). Among patients with this degree of mucositis, the median duration of mucositis was 6 days (range, 1 to 22) in the palifermin group and 9 days (range, 1 to 27) in the placebo group. Among all patients, regardless of the occurrence of mucositis, the median duration of oral mucositis of WHO grade 3 or 4 was 3 days (range, 0 to 22) in the palifermin group and 9 days (range, 0 to 27) in the placebo group (P\u3c0.001). As compared with placebo, palifermin was associated with significant reductions in the incidence of grade 4 oral mucositis (20 percent vs. 62 percent, P\u3c0.001), patient-reported soreness of the mouth and throat (area-under-the-curve score, 29.0 [range, 0 to 98] vs. 46.8 [range, 0 to 110]; P\u3c0.001), the use of opioid analgesics (median, 212 mg of morphine equivalents [range, 0 to 9418] vs. 535 mg of morphine equivalents [range, 0 to 9418], P\u3c0.001), and the incidence of use of total parenteral nutrition (31 percent vs. 55 percent, P\u3c0.001). Adverse events, mainly rash, pruritus, erythema, mouth and tongue disorders, and taste alteration, were mild to moderate in severity and were transient. CONCLUSIONS: Palifermin reduced the duration and severity of oral mucositis after intensive chemotherapy and radiotherapy for hematologic cancers

Agriculture, food security and climate change: Outlook for knowledge, tools and action

Agriculture and food security are key sectors for intervention under climate change. Agricultural production is highly vulnerable even to 2C (lowend) predictions for global mean temperatures in 2100, with major implications for rural poverty and for both rural and urban food security. Agriculture also presents untapped opportunities for mitigation, given the large land area under crops and rangeland, and the additional mitigation potential of aquaculture. This paper presents a summary of current scientific knowledge on the impacts of climate change on farming and food systems, and on the implications for adaptation and mitigation. Many of the trends and impacts are highly uncertain at a range of spatial and temporal scales; we need significant advances in predicting how climate variability and change will affect future food security. Despite these uncertainties, it is clear that the magnitude and rate of projected changes will require adaptation. Actions towards adaptation fall into two broad overlapping areas: (1) better management of agricultural risks associated with increasing climate variability and extreme events, for example improved climate information services and safety nets, and (2) accelerated adaptation to progressive climate change over decadal time scales, for example integrated packages of technology, agronomy and policy options for farmers and food systems. Maximization of agriculture’s mitigation potential will require, among others, investments in technological innovation and agricultural intensification linked to increased efficiency of inputs, and creation of incentives and monitoring systems that are inclusive of smallholder farmers. The challenges posed by climate change to agriculture and food security require a holistic and strategic approach to linking knowledge with action. Key elements of this are greater interactions between decision-makers and researchers in all sectors, greater collaboration among climate, agriculture and food security communities, and consideration of interdependencies across whole food systems and landscapes. Food systems faced with climate change need urgent action in spite of uncertainties