The cognitive neuroscience of visual working memory

Visual working memory allows us to temporarily maintain and manipulate visual information in order to solve a task. The study of the brain mechanisms underlying this function began more than half a century ago, with Scoville and Milner’s (1957) seminal discoveries with amnesic patients. This timely collection of papers brings together diverse perspectives on the cognitive neuroscience of visual working memory from multiple fields that have traditionally been fairly disjointed: human neuroimaging, electrophysiological, behavioural and animal lesion studies, investigating both the developing and the adult brain

The light requirements for growth and photosynthesis in seagrasses with emphasis on Texas estuaries : a literature survey

During the last 20 years, seagrass communities throughout the world have experienced decreased productivity and distribution. These declines have often been attributed to decreased water transparency as a result of turbidity or shading by epiphytic algae. Epiphytic shading is often an indication of nutrient enrichment caused by anthropogenic inputs. Although both epiphytes and turbidity occur as natural phenomena, human activities can exacerbate existing natural conditions with adverse effects on seagrass communities. The objectives of this study were (a) to review the existing literature and data available on the effect of natural and anthropogenic factors on the underwater light environment; (b) to examine the relationship between light and seagrass distribution and productivity; and (c) to make recommendations on how to protect seagrass habitats in Texas bays and estuaries. To meet these goals, we have examined the available literature, emphasizing the physiological response of seagrasses to light and temperature. By using data and observations collected on a variety of species from around the world we may be better able to define the light requirements of Texas seagrasses. A knowledge of the minimum annual light requirements for seagrass growth is necessary to maintain the current distribution of Texas species. This information will also be required in the development of a management plan that permits the expansion and establishment of new seagrass habitat.Submitted to United States Environmental Protection Agency, Region 6 ... Dallas, Tx31 July 1993Marine Scienc

Mesocosm experiments quantify the effects of eutrophication on eelgrass, Zostera marina

Outdoor mesocosm experiments were used to examine the response of eelgrass communities to excess nutrient loading and reduced light that simulated coastal eutrophication. A series of replicated manipulations conducted between 1988 and 1990 demonstrated the effects of reduced available light and increased loading of nitrogen plus phosphorus on habitats dominated by eelgrass Zostera marina L. Shade and nutrients each significantly affected eelgrass growth, morphology, density, and biomass. We found no significant interactions between the effects of shade and the effects of nutrients on any plant characteristics except leaf length. The growth rate of individual eelgrass shoots was linearly related to light, increasing throughout the range of available light. Biomass and daily biomass increase, or areal growth, were also linearly related to light, but specific growth showed no response to light. Shoot density increased with the log of light. Excess nutrient loading was shown to significantly reduce eelgrass growth and bed structure through stimulation of various forms of algae that effectively competed with eelgrass for light. The absence of significant interactions between the effects of shade and nutrients on eelgrass density, growth, and biomass suggests that the negative effect of algae on eelgrass occurs primarily through the reduction of light (i.e. shading). The outcome of nutrient enrichment was a shift in plant dominance from eelgrass to three algal forms: phytoplankton, epiphytic algae, and macroalgae. We quantified the effects of eutrophication and demonstrated that increased nutrient loading results in less light for eelgrass and that eelgrass growth linearly decreases with reduced light

Saliency-driven visual search performance in toddlers with low– vs high–touch screen use

During toddlerhood, a peak period of neurocognitive development, increased exposure to sensory stimulation through touch screen use, may influence developing attentional control. While TV’s rapidly changing, noncontingent flow of sensory information has been hypothesized to lead to difficulties voluntarily focusing attention, video gaming’s contingent and cognitively demanding sensory environments may improve visual processing and attention.3 Toddler touch screen use involves both exogenous attention, driven by salient audio-visual features, and endogenous/voluntary control, eg, video selection and app use. The current study compared high– and low–touch screen users on a gaze-contingent visual search paradigm, assessing exogenous, saliency-based attention (single-feature trials), and endogenous attention control (conjunction trials)

Effects of temperature, salinity and seed age on induction of Zostera japonica germination in North America, USA

Seagrasses can colonize unstructured mudflats either through clonal growth or seed germination and survival. Zostera japonicais an introduced seagrass in North America that has rapidly colonized mudflats along the Pacific Coast, leading to active management of the species. Growth and physiology have been evaluated; however, there is little information about the factors influencing seed germination. We examined the effects of storage and induction temperature (10, 15, 20°C) and salinity (0, 10, 20, 30), and storage period (1.5 and 26 months) on germination of seeds of the seagrass Z. japonicacollected from Yaquina Bay, Oregon, USA. Seed germination at 15 and 20 ◦C was 1.24 times higher than at 10°C. Cumulative seed germination at salinity 0 during the first 28 days was 6.5 times greater than at a salinity of 10; similarly, initial seed germination at a salinity of 10 was 7.3 times greater than that observed for salinity 20 and 30. The proportion of germinated seeds collected in 2011 and stored for 26 months was 1.24 times greater than seeds collected in 2013 that were stored for only 6 weeks. Overall average germination rates were 21.6% and 17.1% for 2011 and 2013, respectively. Our experimental results indicate that salinity had a much stronger control over Z. japonica germination than temperature, and the long storage period suggests that Z. japonica is capable of developing a persistent seed bank. We hypothesize that Z. japonica uses seasonal variations in temperature and salinity to avoid competition between generations favoring germination under conditions that are not optimal for the growth of mature plants

Productivity estimation in Halodule wrightii: comparison of leaf-clipping and leaf-marking techniques, and the importance of clip height

We compared estimates of Halodule wrightii leaf growth rates obtained from leaf-clipping and leaf-piercing methods in a south Texas lagoon. Leaf clipping underestimated leaf production from 15 to 37% in winter and 25 to 60% in summer relative to leaf piercing. The underestimation of leaf-clipping derived growth rates were corrected using a linear regression between leaf growth rates determined by leaf-clipping and leaf-piercing methods. To examine the effect of clip height on H. wrightii leaf growth rate estimation, leaves were clipped at 0, 2, 4, 6, and 8 cm above the sediment. Leaves clipped at 2 cm exhibited the fastest leaf growth rate (average = 3.66 mm d–1) while leaves clipped at 8 cm had the slowest rate (average = 2.30 mm d–1). Depressed leaf growth rates for 8 cm clip height were likely due to the slowing of growth rate with increasing leaf age. Reduced growth rate for the 0 cm clip height treatment may be attributable to removal of nearly all photosynthetic tissue and limited below-ground resources. In design of leaf-clipping studies, it is suggested that the selection of clip height and the period of growth after clipping be optimized for each season of a study

Effects of temperature, salinity and seed age on induction of Zostera japonica germination in North America, USA

Seagrasses can colonize unstructured mudflats either through clonal growth or seed germination and survival. Zostera japonicais an introduced seagrass in North America that has rapidly colonized mudflats along the Pacific Coast, leading to active management of the species. Growth and physiology have been evaluated; however, there is little information about the factors influencing seed germination. We examined the effects of storage and induction temperature (10, 15, 20°C) and salinity (0, 10, 20, 30), and storage period (1.5 and 26 months) on germination of seeds of the seagrass Z. japonicacollected from Yaquina Bay, Oregon, USA. Seed germination at 15 and 20 ◦C was 1.24 times higher than at 10°C. Cumulative seed germination at salinity 0 during the first 28 days was 6.5 times greater than at a salinity of 10; similarly, initial seed germination at a salinity of 10 was 7.3 times greater than that observed for salinity 20 and 30. The proportion of germinated seeds collected in 2011 and stored for 26 months was 1.24 times greater than seeds collected in 2013 that were stored for only 6 weeks. Overall average germination rates were 21.6% and 17.1% for 2011 and 2013, respectively. Our experimental results indicate that salinity had a much stronger control over Z. japonica germination than temperature, and the long storage period suggests that Z. japonica is capable of developing a persistent seed bank. We hypothesize that Z. japonica uses seasonal variations in temperature and salinity to avoid competition between generations favoring germination under conditions that are not optimal for the growth of mature plants

Editorial: the cognitive neuroscience of visual working memory, Volume II

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Visual search performance in infants associates with later ASD diagnosis

An enhanced ability to detect visual targets amongst distractors, known as visual search (VS), has often been documented in Autism Spectrum Disorders (ASD). Yet, it is unclear when this behaviour emerges in development and if it is specific to ASD. We followed up infants at high and low familial risk for ASD to investigate how early VS abilities links to later ASD diagnosis, the potential underlying mechanisms of this association and the specificity of superior VS to ASD. Clinical diagnosis of ASD as well as dimensional measures of ASD, attention-deficit/hyperactivity disorder (ADHD) and anxiety symptoms were ascertained at 3 years. At 9 and 15 months, but not at age 2 years, high-risk children who later met clinical criteria for ASD (HR-ASD) had better VS performance than those without later diagnosis and low-risk controls. Although HR-ASD children were also more attentive to the task at 9 months, this did not explain search performance. Superior VS specifically predicted 3 year-old ASD but not ADHD or anxiety symptoms. Our results demonstrate that atypical perception and core ASD symptoms of social interaction and communication are closely and selectively associated during early development, and suggest causal links between perceptual and social features of ASD