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Готові списки джерел за темами / Top-down and bottom-up interactions / Статті в журналах

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Статті в журналах з теми "Top-down and bottom-up interactions"

Автор: Grafiati

Опубліковано: 4 червня 2021

Оновлено: 13 лютого 2022

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1

McQueen, Donald J., John R. Post, and Edward L. Mills. "Trophic Relationships in Freshwater Pelagic Ecosystems." Canadian Journal of Fisheries and Aquatic Sciences 43, no. 8 (August 1, 1986): 1571–81. http://dx.doi.org/10.1139/f86-195.

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Relative impacts of bottom-up (producer controlled) and top-down (consumer controlled) forces on the biomass and size structure of five major components of freshwater pelagic systems (piscivores, planktivores, zooplankton, phytoplankton, and total phosphorus availability) were estimated. Predictions that emerge are (1) maximum biomass at each trophic level is controlled from below (bottom-up) by nutrient availability, (2) this bottom-up regulation is strongest at the bottom of the food web (i.e. phosphorus → phytoplankton) and weakens by a factor of 2 with each succeeding step up the food web, (3) as energy moves up a food web, the predictability of bottom-up interactions decreases, (4) near the top of the food web, top-down (predator mediated) interactions are strong and have low coefficients of variation, but weaken with every step down the food web, (5) variability around the bottom-up regressions can always be explained by top-down forces, and (6) interplay between top-down and bottom-up effects changes with the trophic status of lakes. In eutrophic lakes, top-down effects are strong for piscivore → zooplankton, weaker for planktivore → zooplankton, and have little impact for zooplankton → phytoplankton. For oligotrophic lakes, the model predicts that top-down effects are not strongly buffered, so that zooplankton → phytoplankton interactions are significant.

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2

Ingber, Lester. "Statistical mechanics of neocortical interactions: EEG eigenfunctions of short-term memory." Behavioral and Brain Sciences 23, no. 3 (June 2000): 403–5. http://dx.doi.org/10.1017/s0140525x00273251.

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This commentary focuses on how bottom-up neocortical models can be developed into eigenfunction expansions of probability distributions appropriate to describe short-term memory in the context of scalp EEG. The mathematics of eigenfunctions are similar to the top-down eigenfunctions developed by Nunez, despite different physical manifestations. The bottom-up eigenfunctions are at the local mesocolumnar scale, whereas the top-down eigenfunctions are at the global regional scale. Our respective approaches have regions of substantial overlap, and future studies may expand top-down eigenfunctions into the bottom-up eigenfunctions, yielding a model of scalp EEG expressed in terms of columnar states of neocortical processing of attention and short-term memory.

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3

Zhong, Zhiwei, Xiaofei Li, Dean Pearson, Deli Wang, Dirk Sanders, Yu Zhu, and Ling Wang. "Ecosystem engineering strengthens bottom-up and weakens top-down effects via trait-mediated indirect interactions." Proceedings of the Royal Society B: Biological Sciences 284, no. 1863 (September 20, 2017): 20170894. http://dx.doi.org/10.1098/rspb.2017.0894.

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Trophic interactions and ecosystem engineering are ubiquitous and powerful forces structuring ecosystems, yet how these processes interact to shape natural systems is poorly understood. Moreover, trophic effects can be driven by both density- and trait-mediated interactions. Microcosm studies demonstrate that trait-mediated interactions may be as strong as density-mediated interactions, but the relative importance of these pathways at natural spatial and temporal scales is underexplored. Here, we integrate large-scale field experiments and microcosms to examine the effects of ecosystem engineering on trophic interactions while also exploring how ecological scale influences density- and trait-mediated interaction pathways. We demonstrate that (i) ecosystem engineering can shift the balance between top-down and bottom-up interactions, (ii) such effects can be driven by cryptic trait-mediated interactions, and (iii) the relative importance of density- versus trait-mediated interaction pathways can be scale dependent. Our findings reveal the complex interplay between ecosystem engineering, trophic interactions, and ecological scale in structuring natural systems.

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4

Sivaloganathan, Darshan M., and Mark P. Brynildsen. "Phagosome–Bacteria Interactions from the Bottom Up." Annual Review of Chemical and Biomolecular Engineering 12, no. 1 (June 7, 2021): 309–31. http://dx.doi.org/10.1146/annurev-chembioeng-090920-015024.

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When attempting to propagate infections, bacterial pathogens encounter phagocytes that encase them in vacuoles called phagosomes. Within phagosomes, bacteria are bombarded with a plethora of stresses that often lead to their demise. However, pathogens have evolved numerous strategies to counter those host defenses and facilitate survival. Given the importance of phagosome–bacteria interactions to infection outcomes, they represent a collection of targets that are of interest for next-generation antibacterials. To facilitate such therapies, different approaches can be employed to increase understanding of phagosome–bacteria interactions, and these can be classified broadly as top down (starting from intact systems and breaking down the importance of different parts) or bottom up (developing a knowledge base on simplified systems and progressively increasing complexity). Here we review knowledge of phagosomal compositions and bacterial survival tactics useful for bottom-up approaches, which are particularly relevant for the application of reaction engineering to quantify and predict the time evolution of biochemical species in these death-dealing vacuoles. Further, we highlight how understanding in this area can be built up through the combination of immunology, microbiology, and engineering.

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5

Young, Richard, and Brian Yandell. "TOP-DOWN VERSUS BOTTOM-UP ANALYSES OF INTERLANGUAGE DATA." Studies in Second Language Acquisition 21, no. 3 (September 1999): 477–88. http://dx.doi.org/10.1017/s0272263199003058.

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We are grateful to Hidetoshi Saito for his careful and reasoned critique of the VARBRUL procedure in his article, “Dependence and Interaction in Frequency Data Analysis in SLA Research” (this issue). Saito reanalyzes Young's (1988, 1991) study of -s plural variation in the English interlanguage of native speakers of Chinese. He raises two criticisms of the statistical analyses in the original work: (a) data from all participants were lumped together, resulting in an analysis that ignores possible variation across participants; and (b) interaction between independent variables was not investigated, whereas Saito finds that an interaction term contributes to a statistical model that fits the data better than the original analysis.

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6

Mechelli, A. "Where Bottom-up Meets Top-down: Neuronal Interactions during Perception and Imagery." Cerebral Cortex 14, no. 11 (May 13, 2004): 1256–65. http://dx.doi.org/10.1093/cercor/bhh087.

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7

McMains, S., and S. Kastner. "Interactions of Top-Down and Bottom-Up Mechanisms in Human Visual Cortex." Journal of Neuroscience 31, no. 2 (January 12, 2011): 587–97. http://dx.doi.org/10.1523/jneurosci.3766-10.2011.

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8

M'hamdi, Ahmed, and Mohamed Nemiche. "Bottom-Up and Top-Down Approaches to Simulate Complex Social Phenomena." International Journal of Applied Evolutionary Computation 9, no. 2 (April 2018): 1–16. http://dx.doi.org/10.4018/ijaec.2018040101.

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Social science research is concerned with the study of processes and phenomena in human societies, institutions and organizations. Social phenomena are complex due to many non-linear interactions between their elements. Social simulation represents a new paradigm for understanding social complexity with approaches that use advanced computational capabilities. The success of social simulation is largely due to its capability to test and validate hypotheses of social phenomena by the construction of virtual laboratories. This paper provides an introduction to social simulation and discusses approaches to model complex social phenomena.

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9

Sharoh, Daniel, Tim van Mourik, Lauren J. Bains, Katrien Segaert, Kirsten Weber, Peter Hagoort, and David G. Norris. "Laminar specific fMRI reveals directed interactions in distributed networks during language processing." Proceedings of the National Academy of Sciences 116, no. 42 (September 30, 2019): 21185–90. http://dx.doi.org/10.1073/pnas.1907858116.

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Interactions between top-down and bottom-up information streams are integral to brain function but challenging to measure noninvasively. Laminar resolution, functional MRI (lfMRI) is sensitive to depth-dependent properties of the blood oxygen level-dependent (BOLD) response, which can be potentially related to top-down and bottom-up signal contributions. In this work, we used lfMRI to dissociate the top-down and bottom-up signal contributions to the left occipitotemporal sulcus (LOTS) during word reading. We further demonstrate that laminar resolution measurements could be used to identify condition-specific distributed networks on the basis of whole-brain connectivity patterns specific to the depth-dependent BOLD signal. The networks corresponded to top-down and bottom-up signal pathways targeting the LOTS during word reading. We show that reading increased the top-down BOLD signal observed in the deep layers of the LOTS and that this signal uniquely related to the BOLD response in other language-critical regions. These results demonstrate that lfMRI can reveal important patterns of activation that are obscured at standard resolution. In addition to differences in activation strength as a function of depth, we also show meaningful differences in the interaction between signals originating from different depths both within a region and with the rest of the brain. We thus show that lfMRI allows the noninvasive measurement of directed interaction between brain regions and is capable of resolving different connectivity patterns at submillimeter resolution, something previously considered to be exclusively in the domain of invasive recordings.

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10

Zhang, Jian, Hong Qian, Marco Girardello, Vincent Pellissier, Scott E. Nielsen, and Jens-Christian Svenning. "Trophic interactions among vertebrate guilds and plants shape global patterns in species diversity." Proceedings of the Royal Society B: Biological Sciences 285, no. 1883 (July 25, 2018): 20180949. http://dx.doi.org/10.1098/rspb.2018.0949.

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Trophic interactions play critical roles in structuring biotic communities. Understanding variation in trophic interactions among systems provides important insights into biodiversity maintenance and conservation. However, the relative importance of bottom-up versus top-down trophic processes for broad-scale patterns in biodiversity is poorly understood. Here, we used global datasets on species richness of vascular plants, mammals and breeding birds to evaluate the role of trophic interactions in shaping large-scale diversity patterns. Specifically, we used non-recursive structural equation models to test for top-down and bottom-up forcing of global species diversity patterns among plants and trophic guilds of mammals and birds (carnivores, invertivores and herbivores), while accounting for extrinsic environmental drivers. The results show that trophic linkages emerged as being more important to explaining species richness than extrinsic environmental drivers. In particular, there were strong, positive top-down interactions between mammal herbivores and plants, and moderate to strong bottom-up and/or top-down interactions between herbivores/invertivores and carnivores. Estimated trophic interactions for separate biogeographical regions were consistent with global patterns. Our findings demonstrate that, after accounting for environmental drivers, large-scale species richness patterns in plant and vertebrate taxa consistently support trophic interactions playing a major role in shaping global patterns in biodiversity. Furthermore, these results suggest that top-down forces often play strong complementary roles relative to bottom-up drivers in structuring biodiversity patterns across trophic levels. These findings underscore the importance of integrating trophic forcing mechanisms into studies of biodiversity patterns.

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11

Ochsner, Kevin N., Rebecca R. Ray, Brent Hughes, Kateri McRae, Jeffrey C. Cooper, Jochen Weber, John D. E. Gabrieli, and James J. Gross. "Bottom-Up and Top-Down Processes in Emotion Generation." Psychological Science 20, no. 11 (November 2009): 1322–31. http://dx.doi.org/10.1111/j.1467-9280.2009.02459.x.

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Emotions are generally thought to arise through the interaction of bottom-up and top-down processes. However, prior work has not delineated their relative contributions. In a sample of 20 females, we used functional magnetic resonance imaging to compare the neural correlates of negative emotions generated by the bottom-up perception of aversive images and by the top-down interpretation of neutral images as aversive. We found that (a) both types of responses activated the amygdala, although bottom-up responses did so more strongly; (b) bottom-up responses activated systems for attending to and encoding perceptual and affective stimulus properties, whereas top-down responses activated prefrontal regions that represent high-level cognitive interpretations; and (c) self-reported affect correlated with activity in the amygdala during bottom-up responding and with activity in the medial prefrontal cortex during top-down responding. These findings provide a neural foundation for emotion theories that posit multiple kinds of appraisal processes and help to clarify mechanisms underlying clinically relevant forms of emotion dysregulation.

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12

Zanette, Liana, and Michael Clinchy. "Food supplementation leads to bottom-up and top-down food-host-parasite interactions." Journal of Animal Ecology 79, no. 6 (July 14, 2010): 1172–80. http://dx.doi.org/10.1111/j.1365-2656.2010.01724.x.

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13

Lev-Ari, Tidhar, and Yoram Gutfreund. "Interactions between top-down and bottom-up attention in barn owls (Tyto alba)." Animal Cognition 21, no. 2 (December 6, 2017): 197–205. http://dx.doi.org/10.1007/s10071-017-1150-2.

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14

MORÉN, JAN, ALEŠ UDE, ANSGAR KOENE, and GORDON CHENG. "BIOLOGICALLY BASED TOP-DOWN ATTENTION MODULATION FOR HUMANOID INTERACTIONS." International Journal of Humanoid Robotics 05, no. 01 (March 2008): 3–24. http://dx.doi.org/10.1142/s0219843608001285.

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An adaptive perception system enables humanoid robots to interact with humans and their surroundings in a meaningful context-dependent manner. An important foundation for visual perception is the selectivity of early vision processes that enables the system to filter out low-level unimportant information while attending to features indicated as important by higher-level processes by way of top-down modulation. We present a novel way to integrate top-down and bottom-up processing for achieving such attention-based filtering. We specifically consider the case where the top-down target is not the most salient in any of the used submodalities.

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15

Sinclair, A. R. E., and Charles J. Krebs. "Complex numerical responses to top–down and bottom–up processes in vertebrate populations." Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 357, no. 1425 (September 29, 2002): 1221–31. http://dx.doi.org/10.1098/rstb.2002.1123.

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Population growth rate is determined in all vertebrate populations by food supplies, and we postulate bottom–up control as the universal primary standard. But this primary control system can be overridden by three secondary controls: top–down processes from predators, social interactions within the species and disturbances. Different combinations of these processes affect population growth rates in different ways. Thus, some relationships between growth rate and density can be hyperbolic or even have multiple nodes. We illustrate some of these in marsupial, ungulate and rabbit populations. Complex interactions between food, predators, environmental disturbance and social behaviour produce the myriad observations of population growth in nature, and we need to develop generalizations to classify populations. Different animal groups differ in the combination of these four processes that affect them, in their growth rates and in their vulnerability to extinction. Because conservation and management of populations depend critically on what factors drive population growth, we need to develop universal generalizations that will relieve us from the need to study every single population before we can make recommendations for management.

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16

Lee, Ji Young, and Mark Hedrick. "Interaction of top-down and bottom-up processing on categorical perception." Journal of the Acoustical Society of America 126, no. 4 (2009): 2302. http://dx.doi.org/10.1121/1.3249488.

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17

Mac Ginty, Roger. "Hybrid Peace: The Interaction Between Top-Down and Bottom-Up Peace." Security Dialogue 41, no. 4 (August 2010): 391–412. http://dx.doi.org/10.1177/0967010610374312.

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18

Van Colen, Carl, Simon F. Thrush, Samantha Parkes, Rachel Harris, Sally A. Woodin, David S. Wethey, Conrad A. Pilditch, Judi E. Hewitt, Andrew M. Lohrer, and Magda Vincx. "Bottom–up and top–down mechanisms indirectly mediate interactions between benthic biotic ecosystem components." Journal of Sea Research 98 (April 2015): 42–48. http://dx.doi.org/10.1016/j.seares.2014.10.016.

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19

Butler, Casey D., and John T. Trumble. "Effects of pollutants on bottom-up and top-down processes in insect–plant interactions." Environmental Pollution 156, no. 1 (November 2008): 1–10. http://dx.doi.org/10.1016/j.envpol.2007.12.026.

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20

Stoler, Aaron B., and Rick A. Relyea. "Bottom-up meets top-down: leaf litter inputs influence predator–prey interactions in wetlands." Oecologia 173, no. 1 (February 6, 2013): 249–57. http://dx.doi.org/10.1007/s00442-013-2595-x.

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21

Blum, Michael J. "Environmental Pressures on Top-Down and Bottom-Up Forces in Coastal Ecosystems." Diversity 13, no. 9 (September 16, 2021): 444. http://dx.doi.org/10.3390/d13090444.

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Global change is manifesting new and potent pressures that may determine the relative influence of top-down and bottom-up forces on the productivity of plants that undergird coastal ecosystems. Here, I present a meta-analysis conducted to assess how herbivory, nitrogen enrichment, and elevated salinity influence plant productivity according to the salinity regimes of coastal ecosystems. An examination of 99 studies representing 288 effect sizes across 76 different plant species revealed that elevated salinity negatively affected productivity across all environments, but particularly in freshwater ecosystems. Nitrogen enrichment, on the other hand, positively affected productivity. In agreement with the plant stress hypothesis, herbivory had the greatest negative impact in saline habitats. This trend, however, appears to reverse with nitrogen enrichment, with maximum losses to herbivory occurring in brackish habitats. These findings demonstrate that multiple stressors can yield complex, and sometimes opposite outcomes to those arising from individual stressors. This study also suggests that trophic interactions will likely shift as coastal ecosystems continue to experience nutrient enrichment and sea level rise.

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22

Kingston, John. "Most but not all bottom-up interactions between signal properties improve categorization." Behavioral and Brain Sciences 23, no. 3 (June 2000): 335–36. http://dx.doi.org/10.1017/s0140525x00333246.

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The massive acoustic redundancy of minimally contrasting speech sounds, coupled with the auditory integration of psychoacoustically similar acoustic properties produces a highly invariant percept, which cannot be improved by top-down feedback from the lexicon. Contextual effects are also bottom-up but not all entirely auditory and may thus differ in whether they affect sensitivity or only response bias.

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23

Lynam, Christopher Philip, Marcos Llope, Christian Möllmann, Pierre Helaouët, Georgia Anne Bayliss-Brown, and Nils C. Stenseth. "Interaction between top-down and bottom-up control in marine food webs." Proceedings of the National Academy of Sciences 114, no. 8 (February 6, 2017): 1952–57. http://dx.doi.org/10.1073/pnas.1621037114.

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Climate change and resource exploitation have been shown to modify the importance of bottom-up and top-down forces in ecosystems. However, the resulting pattern of trophic control in complex food webs is an emergent property of the system and thus unintuitive. We develop a statistical nondeterministic model, capable of modeling complex patterns of trophic control for the heavily impacted North Sea ecosystem. The model is driven solely by fishing mortality and climatic variables and based on time-series data covering >40 y for six plankton and eight fish groups along with one bird group (>20 y). Simulations show the outstanding importance of top-down exploitation pressure for the dynamics of fish populations. Whereas fishing effects on predators indirectly altered plankton abundance, bottom-up climatic processes dominate plankton dynamics. Importantly, we show planktivorous fish to have a central role in the North Sea food web initiating complex cascading effects across and between trophic levels. Our linked model integrates bottom-up and top-down effects and is able to simulate complex long-term changes in ecosystem components under a combination of stressor scenarios. Our results suggest that in marine ecosystems, pathways for bottom-up and top-down forces are not necessarily mutually exclusive and together can lead to the emergence of complex patterns of control.

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24

Dorresteijn, Ine, Jannik Schultner, Dale G. Nimmo, Joern Fischer, Jan Hanspach, Tobias Kuemmerle, Laura Kehoe, and Euan G. Ritchie. "Incorporating anthropogenic effects into trophic ecology: predator–prey interactions in a human-dominated landscape." Proceedings of the Royal Society B: Biological Sciences 282, no. 1814 (September 7, 2015): 20151602. http://dx.doi.org/10.1098/rspb.2015.1602.

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Apex predators perform important functions that regulate ecosystems worldwide. However, little is known about how ecosystem regulation by predators is influenced by human activities. In particular, how important are top-down effects of predators relative to direct and indirect human-mediated bottom-up and top-down processes? Combining data on species' occurrence from camera traps and hunting records, we aimed to quantify the relative effects of top-down and bottom-up processes in shaping predator and prey distributions in a human-dominated landscape in Transylvania, Romania. By global standards this system is diverse, including apex predators (brown bear and wolf), mesopredators (red fox) and large herbivores (roe and red deer). Humans and free-ranging dogs represent additional predators in the system. Using structural equation modelling, we found that apex predators suppress lower trophic levels, especially herbivores. However, direct and indirect top-down effects of humans affected the ecosystem more strongly, influencing species at all trophic levels. Our study highlights the need to explicitly embed humans and their influences within trophic cascade theory. This will greatly expand our understanding of species interactions in human-modified landscapes, which compose the majority of the Earth's terrestrial surface.

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25

Greenville, Aaron C., Glenda M. Wardle, Bobby Tamayo, and Chris R. Dickman. "Bottom-up and top-down processes interact to modify intraguild interactions in resource-pulse environments." Oecologia 175, no. 4 (June 8, 2014): 1349–58. http://dx.doi.org/10.1007/s00442-014-2977-8.

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26

SUN, Ze-kun, Jin-yan WANG, and Fei LUO. "Interaction between Pain and Attention: Bottom-up Capture vs. Top-down Modulation." Advances in Psychological Science 23, no. 12 (2015): 2096. http://dx.doi.org/10.3724/sp.j.1042.2015.02096.

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27

Watson, David M. "Fleshing out facilitation – reframing interaction networks beyond top‐down versus bottom‐up." New Phytologist 211, no. 3 (June 20, 2016): 803–8. http://dx.doi.org/10.1111/nph.14052.

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28

Westerhausen, René, Matthias Moosmann, Kimmo Alho, Svyatoslav Medvedev, Heikki Hämäläinen, and Kenneth Hugdahl. "Top–down and bottom–up interaction: manipulating the dichotic listening ear advantage." Brain Research 1250 (January 2009): 183–89. http://dx.doi.org/10.1016/j.brainres.2008.10.070.

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Crowther, Thomas W., Stephen M. Thomas, Daniel S. Maynard, Petr Baldrian, Kristofer Covey, Serita D. Frey, Linda T. A. van Diepen, and Mark A. Bradford. "Biotic interactions mediate soil microbial feedbacks to climate change." Proceedings of the National Academy of Sciences 112, no. 22 (May 18, 2015): 7033–38. http://dx.doi.org/10.1073/pnas.1502956112.

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Decomposition of organic material by soil microbes generates an annual global release of 50–75 Pg carbon to the atmosphere, ∼7.5–9 times that of anthropogenic emissions worldwide. This process is sensitive to global change factors, which can drive carbon cycle–climate feedbacks with the potential to enhance atmospheric warming. Although the effects of interacting global change factors on soil microbial activity have been a widespread ecological focus, the regulatory effects of interspecific interactions are rarely considered in climate feedback studies. We explore the potential of soil animals to mediate microbial responses to warming and nitrogen enrichment within a long-term, field-based global change study. The combination of global change factors alleviated the bottom-up limitations on fungal growth, stimulating enzyme production and decomposition rates in the absence of soil animals. However, increased fungal biomass also stimulated consumption rates by soil invertebrates, restoring microbial process rates to levels observed under ambient conditions. Our results support the contemporary theory that top-down control in soil food webs is apparent only in the absence of bottom-up limitation. As such, when global change factors alleviate the bottom-up limitations on microbial activity, top-down control becomes an increasingly important regulatory force with the capacity to dampen the strength of positive carbon cycle–climate feedbacks.

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30

Folt, Brian, and Craig Guyer. "Habitat-dependent effects of predatory spiders on prey frogs in a Neotropical wet forest." Journal of Tropical Ecology 37, no. 5 (August 16, 2021): 214–21. http://dx.doi.org/10.1017/s0266467421000274.

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AbstractIn seasonal wet Neotropical forests, many studies have suggested that species-rich terrestrial frog assemblages are regulated bottom-up by the abundance of leaf litter. However, terrestrial frogs are prey to a diverse community of predators, and no studies have tested for top-down effects of predators on this or other anuran assemblages. Here, we used an extensive field dataset to model the relative contribution of food resources, microhabitat resources and predators towards the occupancy and detection of two frog species (Craugastor bransfordii and Oophaga pumilio) at La Selva, Costa Rica. Frog occupancy was most strongly influenced by predatory spiders and secondarily influenced by the abundance of leaf litter. Predators exerted stronger effects on frogs than food resources, and frogs avoided predators more as leaf litter decreased. Detection probability was elevated when predators were present. We found support for bottom-up effects of leaf litter on the terrestrial frog assemblage, but top-down effects by predators exerted stronger effects on frog occupancy and detection. Because predator avoidance varied along a resource gradient, predator and resource effects appear to be dependent, supporting interactions between top-down and bottom-up mechanisms. Climate-driven decreases in leaf litter may drive decreased availability of frog refugia and increased interactions between frogs and predators.

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31

Taddei-Ferretti, C., C. Musio, and S. Santillo. "Non-linearity of the interactions between bottom-up and top-down signals in multistable visual perception." Il Nuovo Cimento D 17, no. 7-8 (July 1995): 941–47. http://dx.doi.org/10.1007/bf02451851.

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Bennie, Jonathan, Thomas W. Davies, David Cruse, Richard Inger, and Kevin J. Gaston. "Cascading effects of artificial light at night: resource-mediated control of herbivores in a grassland ecosystem." Philosophical Transactions of the Royal Society B: Biological Sciences 370, no. 1667 (May 5, 2015): 20140131. http://dx.doi.org/10.1098/rstb.2014.0131.

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Artificial light at night has a wide range of biological effects on both plants and animals. Here, we review mechanisms by which artificial light at night may restructure ecological communities by modifying the interactions between species. Such mechanisms may be top-down (predator, parasite or grazer controlled), bottom-up (resource-controlled) or involve non-trophic processes, such as pollination, seed dispersal or competition. We present results from an experiment investigating both top-down and bottom-up effects of artificial light at night on the population density of pea aphids Acyrthosiphon pisum in a diverse artificial grassland community in the presence and absence of predators and under low-level light of different spectral composition. We found no evidence for top-down control of A. pisum in this system, but did find evidence for bottom-up effects mediated through the impact of light on flower head density in a leguminous food plant. These results suggest that physiological effects of light on a plant species within a diverse plant community can have detectable demographic effects on a specialist herbivore.

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Whittington, Miles A. "Gamma rhythms as liminal operators in sensory processing." Behavioral and Brain Sciences 27, no. 6 (December 2004): 807–8. http://dx.doi.org/10.1017/s0140525x04430180.

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Gamma rhythms are associated with external and internal sensory processing. Within the conceptual framework of “top-down” and “bottom-up” processing, this suggests that gamma represents a format common to both camps. As these oscillations facilitate communication in the temporal domain, they may represent a mechanism by which top-down and bottom-up processing can interact. A breakdown in this interaction may lead to hallucinations.

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König, Peter, Carl Chiang, and Astrid von Stein. "Internal context and top-down processing." Behavioral and Brain Sciences 20, no. 4 (December 1997): 691–92. http://dx.doi.org/10.1017/s0140525x97311601.

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Recent experimental work suggests that the concept of contextual fields should be generalized to allow the modulation of local information extraction by both external and internal context. The external context relates to the coherent information of the stimulus; the internal context refers to the parts of this information which are relevant for behavior. This dual interaction, present at every level of the hierarchy, requires a fundamental unit of processing more complex than a single neuron appears today. We argue that the cortical column supplies the required mechanisms for a separate top-down and bottom-up processing and allows for interaction without destructive cross-talk. This flexibility might explain why the same basic architecture of a cortical column is used in the whole isocortex.

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Wallach, Wendell, Colin Allen, and Iva Smit. "Machine morality: bottom-up and top-down approaches for modelling human moral faculties." AI & SOCIETY 22, no. 4 (March 9, 2007): 565–82. http://dx.doi.org/10.1007/s00146-007-0099-0.

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Sridhar, Smriti, Younghoon Kwon MD., Yeilim Cho MD., and Inki Kim PhD. "An Adaptive Fuzzy Modeling of Visual Attention in Real-world Interaction with Health Information System." Proceedings of the Human Factors and Ergonomics Society Annual Meeting 64, no. 1 (December 2020): 249–53. http://dx.doi.org/10.1177/1071181320641059.

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Bottom-up and top-down processes are the two mechanisms of visual attention allocation, which allow people to efficiently spot task-relevant stimuli from cluttered and noisy environments, while staying alert to abnormalities within the visual field of view. This paper presents a preliminary study of the physicians’ real-life interaction with Information Communication Technology (ICT) in their own offices, along with extensively analyzing one case of an hour-long interaction of a physician, in which one performs a daily routine of reviewing patient electronic health records (EHRs) and writing diagnostic notes to the system interface. The physician interactions were captured in a time series data by recording display screen, keystrokes and mouse movements, also by simultaneously tracking eye movements. Then, a fuzzy-based model that can distinguish bottom-up and top-down processes were defined by using statistical random variables in terms of eye-movement patterns. The shift between those two attentional processes was detected by tracking the parametric changes of gaze behaviors as input: significant shift of fixation, sustained gazing, and fixation trajectory over time. Based on those gaze metrics, a random variable was assigned to the discrete probability of low (0), medium (0.5), or high (1.0), for a quantified fuzzy output, which was further machine-learned into an Adaptive Neuro-Fuzzy Inference System (ANFIS) model in order to judge how a physician is likely to be dominated by a bottom-up or top-down processes in performing a task at that instance in time. On training the ANFIS model with three different types of fuzzy membership functions (Gaussian, triangular and trapezoidal), the model performed best with the Gaussian function (after 100 iterations, the predicted root mean-square error (RMSE) converged at 0.07%, yielding a smooth linear curve). For a proof-of concept, the model was implemented by using one physician’s gaze behaviors, of which the average, machine-learned fuzzy output probability indicated that the physician was veering toward bottom-up visual attention. This individualized, task-specific pattern of visual attention has implications for the designs of intelligent interface in ICT. Our ANFIS model can scale up to different physicians and tasks to predict the likelihood of bottom-up or top-down information processing based on real-world gaze behaviors.

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Gailer, Jürgen. "Metal Species in Biology: Bottom-Up and Top-Down LC Approaches in Applied Toxicological Research." ISRN Chromatography 2013 (June 10, 2013): 1–21. http://dx.doi.org/10.1155/2013/801840.

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Since the inception of liquid chromatography (LC) more than 100 years ago this separation technique has been developed into a powerful analytical tool that is frequently applied in life science research. To this end, unique insights into the interaction of metal species (throughout this manuscript “metal species” refers to “toxic metals, metalloid compounds, and metal-based drugs” and “toxic metals” to “toxic metals and metalloid compounds”) with endogenous ligands can be obtained by using LC approaches that involve their hyphenation with inductively coupled plasma-based element specific detectors. This review aims to provide a synopsis of the different LC approaches which may be employed to advance our understanding of these interactions either in a “bottom-up” or a “top-down” manner. In the “bottom-up” LC-configuration, endogenous ligands are introduced into a physiologically relevant mobile phase buffer, and the metal species of interest is injected. Subsequent “interrogation” of the on-column formed complex(es) by employing a suitable separation mechanism (e.g., size exclusion chromatography or reversed-phase LC) while changing the ligand concentration(s), the column temperature or the pH can provide valuable insight into the formation of complexes under near physiological conditions. This approach allows to establish the relative stability and hydrophobicity of metal-ligand complexes as well as the dynamic coordination of a metal species (injected) to two ligands (dissolved in the mobile phase). Conversely, the “top-down” analysis of a biological fluid (e.g., blood plasma) by LC (e.g., using size exclusion chromatography) can be used to determine the size distribution of endogenous metalloproteins which are collectively referred to as the “metalloproteome”. This approach can provide unique insight into the metabolism and the plasma protein binding of metal species, and can simultaneously visualize the dose-dependent perturbation of the metalloproteome by a particular metal species. The concerted application of these LC approaches is destined to provide new insight into biochemical processes which represent an important starting point to advance human health in the 21st century.

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Diaz-Cruz, J. L., W. G. Hollik, and U. J. Saldana-Salazar. "A bottom-up approach to the strong CP problem." International Journal of Modern Physics A 33, no. 14n15 (May 28, 2018): 1850088. http://dx.doi.org/10.1142/s0217751x18500884.

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The strong CP problem is one of many puzzles in the theoretical description of elementary particle physics that still lacks an explanation. While top-down solutions to that problem usually comprise new symmetries or fields or both, we want to present a rather bottom-up perspective. The main problem seems to be how to achieve small CP violation in the strong interactions despite the large CP violation in weak interactions. In this paper, we show that with minimal assumptions on the structure of mass (Yukawa) matrices, they do not contribute to the strong CP problem and thus we can provide a pathway to a solution of the strong CP problem within the structures of the Standard Model and no extension at the electroweak scale is needed. However, to address the flavor puzzle, models based on minimal SU(3) flavor groups leading to the proposed flavor matrices are favored. Though we refrain from an explicit UV completion of the Standard Model, we provide a simple requirement for such models not to show a strong CP problem by construction.

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Yahoodik, Sarah, and Yusuke Yamani. "Attentional Control in Young Drivers: Does Training Impact Hazard Anticipation in Dynamic Environments?" Proceedings of the Human Factors and Ergonomics Society Annual Meeting 64, no. 1 (December 2020): 1986–90. http://dx.doi.org/10.1177/1071181320641478.

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The interaction between top-down and bottom-up processing is a way to characterize control of visual attention, but it has not been extensively applied to the driving domain. The Risk Awareness and Perception Training (RAPT) has been effective in improving drivers’ latent hazard anticipation, a top-down process. However, it is unclear whether RAPT protects drivers from being distracted by salient items on the roadway, diminishing latent hazard anticipation. The current driving simulator study examines the potential interaction between bottom-up and top-down processes by having RAPT-and Placebo-trained drivers navigate simulated environments with latent hazards and a stationary or dynamically moving pedestrian. While RAPT-trained drivers were better able to anticipate latent hazards than Placebo-trained drivers, presence of salient, bottom-up stimuli did not negatively impact hazard anticipation performance in either group. This implies RAPT-trained drivers were able to successfully divide their attention, anticipating latent hazards even in the presence of dynamic, driving-relevant objects.

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Bitan, Tali, Jimmy Cheon, Dong Lu, Douglas D. Burman, and James R. Booth. "Developmental Increase in Top–Down and Bottom–Up Processing in a Phonological Task: An Effective Connectivity, fMRI Study." Journal of Cognitive Neuroscience 21, no. 6 (June 2009): 1135–45. http://dx.doi.org/10.1162/jocn.2009.21065.

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We examined age-related changes in the interactions among brain regions in children performing rhyming judgments on visually presented words. The difficulty of the task was manipulated by including a conflict between task-relevant (phonological) information and task-irrelevant (orthographic) information. The conflicting conditions included pairs of words that rhyme despite having different spelling patterns (jazz–has), or words that do not rhyme despite having similar spelling patterns (pint–mint). These were contrasted with nonconflicting pairs that have similar orthography and phonology (dime–lime) or different orthography and phonology (press–list). Using fMRI, we examined effective connectivity among five left hemisphere regions of interest: fusiform gyrus (FG), inferior frontal gyrus (IFG), intraparietal sulcus (IPS), lateral temporal cortex (LTC), and medial frontal gyrus (MeFG). Age-related increases were observed in the influence of the IFG and FG on the LTC, but only in conflicting conditions. These results reflect a developmental increase in the convergence of bottom–up and top–down information on the LTC. In older children, top–down control process may selectively enhance the sensitivity of the LTC to bottom–up information from the FG. This may be evident especially in situations that require selective enhancement of task-relevant versus task-irrelevant information. Altogether these results provide a direct evidence for a developmental increase in top–down control processes in language processing. The developmental increase in bottom–up processing may be secondary to the enhancement of top–down processes.

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Mechelli, Andrea, Cathy J. Price, Uta Noppeney, and Karl J. Friston. "A Dynamic Causal Modeling Study on Category Effects: Bottom–Up or Top–Down Mediation?" Journal of Cognitive Neuroscience 15, no. 7 (October 1, 2003): 925–34. http://dx.doi.org/10.1162/089892903770007317.

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In this study, we combined functional magnetic resonance imaging (fMRI) and dynamic causal modeling (DCM) to investigate whether object category effects in the occipital and temporal cortex are mediated by inputs from early visual cortex or parietal regions. Resolving this issue may provide anatomical constraints on theories of category specificity— which make different assumptions about the underlying neurophysiology. The data were acquired by Ishai, Ungerleider, Martin, Schouten, and Haxby (1999, 2000) and provided by the National fMRI Data Center (http://www.fmridc.org). The original authors used a conventional analysis to estimate differential effects in the occipital and temporal cortex in response to pictures of chairs, faces, and houses. We extended this approach by estimating neuronal interactions that mediate category effects using DCM. DCM uses a Bayesian framework to estimate and make inferences about the influence that one region exerts over another and how this is affected by experimental changes. DCM differs from previous approaches to brain connectivity, such as multivariate autoregressive models and structural equation modeling, as it assumes that the observed hemodynamic responses are driven by experimental changes rather than endogenous noise. DCM therefore brings the analysis of brain connectivity much closer to the analysis of regionally specific effects usually applied to functional imaging data. We used DCM to estimate the influence that V3 and the superior/inferior parietal cortex exerted over category-responsive regions and how this was affected by the presentation of houses, faces, and chairs. We found that category effects in occipital and temporal cortex were mediated by inputs from early visual cortex. In contrast, the connectivity from the superior/inferior parietal area to the category-responsive areas was unaffected by the presentation of chairs, faces, or houses. These findings indicate that category effects in the occipital and temporal cortex can be mediated by bottom–up mechanisms—a finding that needs to be embraced by models of category specificity.

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Ferreira, Camilo M., Sean D. Connell, Silvan U. Goldenberg, and Ivan Nagelkerken. "Positive species interactions strengthen in a high-CO 2 ocean." Proceedings of the Royal Society B: Biological Sciences 288, no. 1954 (July 7, 2021): 20210475. http://dx.doi.org/10.1098/rspb.2021.0475.

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Negative interactions among species are a major force shaping natural communities and are predicted to strengthen as climate change intensifies. Similarly, positive interactions are anticipated to intensify and could buffer the consequences of climate-driven disturbances. We used in situ experiments at volcanic CO 2 vents within a temperate rocky reef to show that ocean acidification can drive community reorganization through indirect and direct positive pathways. A keystone species, the algal-farming damselfish Parma alboscapularis, enhanced primary productivity through its weeding of algae whose productivity was also boosted by elevated CO 2 . The accelerated primary productivity was associated with increased densities of primary consumers (herbivorous invertebrates), which indirectly supported increased secondary consumers densities (predatory fish) (i.e. strengthening of bottom-up fuelling). However, this keystone species also reduced predatory fish densities through behavioural interference, releasing invertebrate prey from predation pressure and enabling a further boost in prey densities (i.e. weakening of top-down control). We uncover a novel mechanism where a keystone herbivore mediates bottom-up and top-down processes simultaneously to boost populations of a coexisting herbivore, resulting in altered food web interactions and predator populations under future ocean acidification.

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Erdoğan, Şeyda, Meryem Beklİoğlu, Elena Litchman, Elizabeth T. Miller, Etі E. Levі, Tuba Bucak, and Ülkü Nіhan Tavşanoğlu. "Determinants of phytoplankton size structure in warm, shallow lakes." Journal of Plankton Research 43, no. 3 (May 2021): 353–66. http://dx.doi.org/10.1093/plankt/fbab035.

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Abstract Body size is an important trait of any organism, including phytoplankton, because it affects physiological and morphological performance, reproduction, population growth rate and competitive interactions. Understanding how interacting top-down and bottom-up factors influence phytoplankton cell size in different aquatic environments is still a challenge. Structural equation modeling (SEM) is a comprehensive multivariate statistical tool for detecting cause–effect relationship among different variables and their hierarchical structure in complex networks (e.g. trophic interactions in ecosystems). Here, several SEM models were employed to investigate the direct and indirect interaction pathways affecting the phytoplankton size structure in 44 mostly eutrophic and hypereutrophic permanent lakes in western Turkey. Among the 15 environmental variables tested, only rotifers and Carlson’s Trophic Index (TSI) had significant direct positive effect on the mean phytoplankton size and size variance, respectively. The results indicate that both bottom-up and top-down factors significantly affect phytoplankton community size structure in eutrophic and hypereutrophic lakes in warm climates. Rotifer grazing increased the abundance of large-sized phytoplankton species, such as filamentous and colonial cyanobacteria and TSI affected phytoplankton size variance, with a higher size variance in hypereutrophic lakes.

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Intaitė, Monika, Valdas Noreika, Alvydas Šoliūnas, and Christine M. Falter. "Interaction of bottom-up and top-down processes in the perception of ambiguous figures." Vision Research 89 (August 2013): 24–31. http://dx.doi.org/10.1016/j.visres.2013.06.011.

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45

Wilkinson, Marcia. "The need for interaction between the “top-down” and “bottom-up” approaches to migraine." Cephalalgia 13, no. 12_suppl (April 1993): 25–26. http://dx.doi.org/10.1177/0333102493013s1206.

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46

Shah, Priti, and Eric G. Freedman. "Bar and Line Graph Comprehension: An Interaction of Top-Down and Bottom-Up Processes." Topics in Cognitive Science 3, no. 3 (December 11, 2009): 560–78. http://dx.doi.org/10.1111/j.1756-8765.2009.01066.x.

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47

Ruthruff, Eric, Roger W. Remington, and James C. Johnston. "Switching between simple cognitive tasks: The interaction of top-down and bottom-up factors." Journal of Experimental Psychology: Human Perception and Performance 27, no. 6 (2001): 1404–19. http://dx.doi.org/10.1037/0096-1523.27.6.1404.

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48

Oransky, Natalie A., Paula R. Skedsvold, and Arthur D. Fisk. "The Interaction of Bottom-up and Top-down Consistency in the Development of Skills." Proceedings of the Human Factors Society Annual Meeting 31, no. 9 (September 1987): 1044–48. http://dx.doi.org/10.1177/154193128703100927.

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An experiment is reported that was conducted to examine the possible value of higher-order consistency in skill development. Subjects made judgments about ordinal properties of stimuli. The presence or absence of consistency was defined by the type of decision – consistent or varied decisions. In both decision conditions the stimuli were inconsistent at the individual stimulus level; however, subjects making consistent decisions concerning the stimuli could make use of consistent relationships among the stimuli. Subjects in the consistent decision were faster and more accurate at identifying target stimuli when compared with the inconsistent decision subjects. In addition to the quantitative differences, subjects receiving consistent decision training were qualitatively different in performance when compared to the inconsistent decision group. The pattern of results from the present experiment is quite consistent with previous memory/visual search investigations. The experiment supports the suggestion that local level (or stimulus based) consistency is not necessary for automatic process development if task relevant higher-order (or global) consistency can be identified and used by the trainees.

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Macaluso, Emiliano, Uta Noppeney, Durk Talsma, Tiziana Vercillo, Jess Hartcher-O’Brien, and Ruth Adam. "The Curious Incident of Attention in Multisensory Integration: Bottom-up vs. Top-down." Multisensory Research 29, no. 6-7 (2016): 557–83. http://dx.doi.org/10.1163/22134808-00002528.

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The role attention plays in our experience of a coherent, multisensory world is still controversial. On the one hand, a subset of inputs may be selected for detailed processing and multisensory integration in a top-down manner, i.e., guidance of multisensory integration by attention. On the other hand, stimuli may be integrated in a bottom-up fashion according to low-level properties such as spatial coincidence, thereby capturing attention. Moreover, attention itself is multifaceted and can be describedviaboth top-down and bottom-up mechanisms. Thus, the interaction between attention and multisensory integration is complex and situation-dependent. The authors of this opinion paper are researchers who have contributed to this discussion from behavioural, computational and neurophysiological perspectives. We posed a series of questions, the goal of which was to illustrate the interplay between bottom-up and top-down processes in various multisensory scenarios in order to clarify the standpoint taken by each author and with the hope of reaching a consensus. Although divergence of viewpoint emerges in the current responses, there is also considerable overlap: In general, it can be concluded that the amount of influence that attention exerts on MSI depends on the current task as well as prior knowledge and expectations of the observer. Moreover stimulus properties such as the reliability and salience also determine how open the processing is to influences of attention.

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Schmidt, Theresa, Yu Xiang, Xujin Bao, and Tao Sun. "A Paradigm Shift in Tissue Engineering: From a Top–Down to a Bottom–Up Strategy." Processes 9, no. 6 (May 26, 2021): 935. http://dx.doi.org/10.3390/pr9060935.

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Tissue engineering (TE) was initially designed to tackle clinical organ shortage problems. Although some engineered tissues have been successfully used for non-clinical applications, very few (e.g., reconstructed human skin) have been used for clinical purposes. As the current TE approach has not achieved much success regarding more broad and general clinical applications, organ shortage still remains a challenging issue. This very limited clinical application of TE can be attributed to the constraints in manufacturing fully functional tissues via the traditional top–down approach, where very limited cell types are seeded and cultured in scaffolds with equivalent sizes and morphologies as the target tissues. The newly proposed developmental engineering (DE) strategy towards the manufacture of fully functional tissues utilises a bottom–up approach to mimic developmental biology processes by implementing gradual tissue assembly alongside the growth of multiple cell types in modular scaffolds. This approach may overcome the constraints of the traditional top–down strategy as it can imitate in vivo-like tissue development processes. However, several essential issues must be considered, and more mechanistic insights of the fundamental, underpinning biological processes, such as cell–cell and cell–material interactions, are necessary. The aim of this review is to firstly introduce and compare the number of cell types, the size and morphology of the scaffolds, and the generic tissue reconstruction procedures utilised in the top–down and the bottom–up strategies; then, it will analyse their advantages, disadvantages, and challenges; and finally, it will briefly discuss the possible technologies that may overcome some of the inherent limitations of the bottom–up strategy.

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