Functional imaging of the neural components of Drosophila motion detection

In order to safely move through the environment, visually-guided animals use several types of visual cues for orientation. Optic flow provides faithful information about ego-motion and can thus be used to maintain a straight course. Additionally, local motion cues or landmarks indicate potentially interesting targets or signal danger, triggering approach or avoidance, respectively. The visual system must reliably and quickly evaluate these cues and integrate this information in order to orchestrate behavior. The underlying neuronal computations for this remain largely inaccessible in higher organisms, such as in humans, but can be studied experimentally in more simple model species. The fly Drosophila, for example, relies heavily on such visual cues during its impressive flight maneuvers. Additionally, it is genetically and physiologically accessible. Therefore, it is regarded as an ideal model organism for exploring neuronal computations underlying visual processing. During my PhD-thesis, I characterized neurons presynaptic to direction selective lobula plate tangential cells by exploiting the genetic toolbox of the fruit fly in combination with in-vivo imaging. The use of genetically encoded calcium indicators and two-photon microscopy allowed me to directly investigate response properties of small columnar neurons upstream of lobula plate wide field neurons. In the highly collaborative environment of our lab my imaging experiments were complemented by several other approaches, including electrophysiological and behavioral experiments, along with modeling which resulted in the publications that comprise this cumulative dissertation. Measuring calcium signals in T4 and T5 cells in the first study, established that both populations of neurons exhibit direction selective response properties. Furthermore, T4 cells only respond to moving bright edges, whereas T5 cells encode exclusively dark edge motion. Silencing the synaptic output of T4 and T5 separately, we were able to determine that both lobula plate tangential cell responses as well as the turning behavior of walking flies were impaired only to bright or dark edges, respectively. We thus proposed that the detection of the direction of visual motion must happen either presynaptic to, or on the dendrites of T4 and T5 neurons, and that this computation takes place independently for brightness increments and decrements. The second paper published in 2014 was motivated by an anatomical study that found an asymmetric wiring between L2 and L4 cells with the dendrites of Tm2 in the distal medulla. Using two-photon calcium imaging and neuronal silencing combined with postsynaptic electrophysiological recordings, we probed the contribution of L4 and Tm2 in the OFF pathway of Drosophila motion vision. We found that while Tm2 have small, isotropic, laterally inhibited receptive fields, L4 cells respond to both, small and large field darkening. Blocking the output of both cell types resulted in a strong impairment of OFF motion vision. In contrast to the anatomical prediction, we did not observe any directional effects for either of the cells

Accessibility of Thai university websites: Awareness, barriers and drivers for accessible practice

Governments and organizations have to respond to a range of legislative and policy initiatives intended to promote equal opportunity for all. The Thai government has passed a number of laws which aim to protect its citizens from discrimination and from breaches of their human rights by government departments and agencies. The Persons with Disabilities Education Act B.E. 2551 (2008) and the Thailand Information and Communication Technology (ICT) Policy Framework (2011-2020) required government agencies to delivery equal education and access to online information for all Thais. Most Thai universities receive government subsidies, and therefore have an obligation to contribute to national prosperity so that all Thais can benefit from their activities, or as the Ministry of Information and Communication Technology and The National Electronics and Computer Technology Centre (2011, p. 23) states “The creation of content, database, online content which promotes lifelong learning, the development of school websites and other digital content should follow the web accessibility standard”. Given the Thai government’s commitment to lifelong learning and the creation of accessible materials, this thesis sought to investigate to what level Thai universities were implementing web accessibility in their websites and e-learning materials. A mixed method approach was employed in order to explore the level of accessibility awareness, barriers to web accessibility implementation and possible drivers for accessibility uptake which might exist within Thai universities. Quantitative data derived from automated and manual web evaluations was gathered based on WCAG 2.0 guideline in order to determine the actual levels of accessible design apparent in Thai university websites. Fifty representative universities were selected from the top ranked Thai universities and a number webpages were tested from within each of the university websites. In addition, online surveys were conducted with three stakeholder groups within the Thai university sector, namely lecturers, web staff and senior managers. These surveys were design to set the context for quantitative website assessment findings and provide evidence as to these stakeholders understanding of web accessibility as a concept. Finally, follow-up interviews were conducted after the web assessments and surveys were analysed so as to reduce ambiguity and increase understanding, creating a very clear picture of the standing of web accessibility in Thailand’s universities. The findings of the data analysis indicate that Thai universities have low levels of web accessibility implementation in their websites and e-learning materials, even though web accessibility requirements had been embedded in Thai laws and policies for over a decade. In terms of web evaluation, the university webpages had accessibility problems across all aspects of WCAG 2.0’s POUR principles, with not a single tested webpage passing even the lowest level of WCAG 2.0 compliance. The survey and interview data revealed very low levels of awareness of web accessibility amongst Thai university staff members as well as lack of knowledge regarding students with disabilities and their specialised technology needs. Whilst Thai university staff were generally supportive of the concept of web accessibility and supporting students with special needs, this was accompanied by some less supportive views, including students with disabilities being taught only in specialised educational facilities or only where there were sufficient numbers of such students to make the investment in accessibility worthwhile. A number of universities in this study featured university admission requirements which could be classed as a discriminatory and not aligned with the requirements of the Thai government. In fact, this thesis revealed an almost total lack of awareness within the Thai university sector of Thai government policy regarding web accessibility and equality in education. This thesis proposed a Smart Thailand : Accessible Learning model and an associated implementation framework which together might lead to an environment in which Thai universities would be more willing and able to implement the tenets of web accessibility and provide an equitable learning experience for all Thai citizens, especially those with disabilities

Analyze Strategies for Diversifying the Country's Economy Driven by Tourism Using Pattaya, Chonburi, Thailand as a Case Study. To Reduce Fragility and Increase Economic Stability

Purpose: This study investigates ways to enhance economic stability in tourism-dependent regions, using Pattaya, Chonburi, Thailand, as a case study. Theoretical Reference: Thailand's heavy reliance on tourism, constituting about 17% of its GDP, sets the context. The study gathers insights from SMEs in Chonburi Province through in-depth interviews. Method: In-depth interviews with SMEs reveal challenges faced by small hotel businesses, including high taxation and substantial expenses, with a focus on labor costs and pre-existing issues like excessive charges.   Results and Conclusion: Prioritizing the hotel industry over attracting new tourists is key. Post-COVID-19 economic stability in Pattaya's tourism industry requires a comprehensive approach involving industry revitalization, diversification, support for local businesses, sustainable practices, infrastructure investments, marketing, and government-industry collaboration. Implications of Research: This research underscores the importance of addressing challenges in tourism-driven regions during crises and offers practical insights for safeguarding economic stability. Originality/Value: The study's unique focus on Pattaya provides valuable insights for similar regions, offering strategies to mitigate vulnerabilities caused by external shocks like pandemics

Functional imaging of the neural components of Drosophila motion detection

In order to safely move through the environment, visually-guided animals use several types of visual cues for orientation. Optic flow provides faithful information about ego-motion and can thus be used to maintain a straight course. Additionally, local motion cues or landmarks indicate potentially interesting targets or signal danger, triggering approach or avoidance, respectively. The visual system must reliably and quickly evaluate these cues and integrate this information in order to orchestrate behavior. The underlying neuronal computations for this remain largely inaccessible in higher organisms, such as in humans, but can be studied experimentally in more simple model species. The fly Drosophila, for example, relies heavily on such visual cues during its impressive flight maneuvers. Additionally, it is genetically and physiologically accessible. Therefore, it is regarded as an ideal model organism for exploring neuronal computations underlying visual processing. During my PhD-thesis, I characterized neurons presynaptic to direction selective lobula plate tangential cells by exploiting the genetic toolbox of the fruit fly in combination with in-vivo imaging. The use of genetically encoded calcium indicators and two-photon microscopy allowed me to directly investigate response properties of small columnar neurons upstream of lobula plate wide field neurons. In the highly collaborative environment of our lab my imaging experiments were complemented by several other approaches, including electrophysiological and behavioral experiments, along with modeling which resulted in the publications that comprise this cumulative dissertation. Measuring calcium signals in T4 and T5 cells in the first study, established that both populations of neurons exhibit direction selective response properties. Furthermore, T4 cells only respond to moving bright edges, whereas T5 cells encode exclusively dark edge motion. Silencing the synaptic output of T4 and T5 separately, we were able to determine that both lobula plate tangential cell responses as well as the turning behavior of walking flies were impaired only to bright or dark edges, respectively. We thus proposed that the detection of the direction of visual motion must happen either presynaptic to, or on the dendrites of T4 and T5 neurons, and that this computation takes place independently for brightness increments and decrements. The second paper published in 2014 was motivated by an anatomical study that found an asymmetric wiring between L2 and L4 cells with the dendrites of Tm2 in the distal medulla. Using two-photon calcium imaging and neuronal silencing combined with postsynaptic electrophysiological recordings, we probed the contribution of L4 and Tm2 in the OFF pathway of Drosophila motion vision. We found that while Tm2 have small, isotropic, laterally inhibited receptive fields, L4 cells respond to both, small and large field darkening. Blocking the output of both cell types resulted in a strong impairment of OFF motion vision. In contrast to the anatomical prediction, we did not observe any directional effects for either of the cells

The Semantics of Verbal Categories in Nakh-Daghestanian Languages: tense, aspect, evidentiality, mood and modality

[Extract] This book explores the semantics of tense, aspect, modality and evidentiality in Nakh-Daghestanian (North-East Caucasian) languages. From a general point of view, these verbal categories and the conceptual relations between the four semantic domains are interesting for linguists from various theoretical and areal backgrounds as well as for researchers from other fields (philosophy of language, cognition, etc.). Virtually all sentences carry informaiton about tense, aspect, modality, and in many languages also evidentiality. Within individual languages, these domains are commonly formally and functionally interrelated. This raises questions about the categorization and the status of the forms and how we can deal with them when writing grammars of specific languages, expecially when there is no established research tradition for the languages in question

A predictive focus of gain modulation encodes target trajectories in insect vision

Published: 25 July 2017When a human catches a ball, they estimate future target location based on the current trajectory. How animals, small and large, encode such predictive processes at the single neuron level is unknown. Here we describe small target-selective neurons in predatory dragonflies that exhibit localized enhanced sensitivity for targets displaced to new locations just ahead of the prior path, with suppression elsewhere in the surround. This focused region of gain modulation is driven by predictive mechanisms, with the direction tuning shifting selectively to match the target's prior path. It involves a large local increase in contrast gain which spreads forward after a delay (e.g. an occlusion) and can even transfer between brain hemispheres, predicting trajectories moved towards the visual midline from the other eye. The tractable nature of dragonflies for physiological experiments makes this a useful model for studying the neuronal mechanisms underlying the brain's remarkable ability to anticipate moving stimuli.Steven D Wiederman, Joseph M Fabian, James R Dunbier, David C O'Carrol

Responses of Drosophila giant descending neurons to visual and mechanical stimuli

In Drosophila, the paired giant descending neurons (GDNs), also known as giant fibers, and the paired giant antennal mechanosensory descending neurons (GAMDNs), are supplied by visual and mechanosensory inputs. Both neurons have the largest cell bodies in the brain and both supply slender axons to the neck connective. The GDN axon thereafter widens to become the largest axon in the thoracic ganglia, supplying information to leg extensor and wing depressor muscles. The GAMDN axon remains slender, interacting with other descending neuron axons medially. GDN and GAMDN dendrites are partitioned to receive inputs from antennal mechanosensory afferents and inputs from the optic lobes. Although GDN anatomy has been well studied in Musca domestica, less is known about the Drosophila homolog, including electrophysiological responses to sensory stimuli. Here we provide detailed anatomical comparisons of the GDN and the GAMDN, characterizing their sensory inputs. The GDN showed responses to light-on and light-off stimuli, expanding stimuli that result in luminance decrease, mechanical stimulation of the antennae, and combined mechanical and visual stimulation. We show that ensembles of lobula columnar neurons (type Col A) and mechanosensory antennal afferents are likely responsible for these responses. The reluctance of the GDN to spike in response to stimulation confirms observations of the Musca GDN. That this reluctance may be a unique property of the GDN is suggested by comparisons with the GAMDN, in which action potentials are readily elicited by mechanical and visual stimuli. The results are discussed in the context of descending pathways involved in multimodal integration and escape responses

Cтехиометрия и структура планктонных сообществ в литорали и пелагиали двух озер разного трофического статуса в Беларуси

Stoichiometric C : N : P ratios were compared between primary producers in littoral and pelagic ecosystems of mesotrophic relatively shallow lake Obsterno and shallow macrophyte covered low trophic lake Nobisto from May to October over the next two years. Elemental seston ratios of lake Obsterno revealed smaller differences between littoral and pelagic zones in comparison with lake Nobisto in 2017. During the studied period, in the both lakes, the seston C : N and C : P ratios were higher than the Redfield ratio (106 : 16 : 1 C : N : P) on most dates and N : P was always more than 16. Pelagic C : P and N : P ratios in lake Obsterno were the highest in May in 2017, July and September in 2018 with significant differences between littoral and pelagic zones. N : P ratios decreased in October but there were no significant differences among habitats. In lake Nobisto in 2018, seston C : P and N : P ratios increased from May to July in littoral and pelagic zones but then decreased in September to October. Our research shows differences in stoichiometric ratios in littoral and pelagic zones of these two lakes, which indicates food quality (seston C : N : P ratios) differences for zooplankton species depending on season and location.Изучали стехиометрию сестона (соотношения C : N : P) двух мелководных озер разной трофности – мезотрофного озера Обстерно и дистрофного макрофитного типа озера Нобисто в течение двух последовательных лет. Сравнивали сезонные изменения в стехиометрии продуцентов в литоральной и пелагической зонах. Соотношения элементов в сестоне оз. Обстерно выявили меньшие различия между литоральной и пелагической зонами по сравнению с оз. Нобисто в 2017 г. В течение исследуемого периода в обоих озерах соотношения C : N и C : P в сестоне были выше классического соотношения Редфилда (C106  : N16  : P1), а соотношение N : P всегда превышало 16. Соотношения C : P в пелагиали оз. Обстерно имели самые высокие показатели в мае 2017 г., а N : P в июле и сентябре 2018 г. со значимыми различиями между литоральной и пелагической зонами, но соотношения N : P уменьшились в октябре и не различались между местообитаниями. В оз. Нобисто в 2018 г. соотношения C : P и N : P в сестоне увеличивались с мая по июль в прибрежной и пелагической зонах, но затем снижались осенью. Как показали наши исследования, сезонные различия в стехиометрии сестона двух озер (соотношение C : N : P как показатель качества пищи) в разных местообитаниях отражают видовой состав фитопланктона, а также структуру сообществ зоопланктона, изменяющуюся в течение сезона и между местообитаниями

Is 3C111, an apparently normal radio galaxy, the counterpart of 3EG J0416+3650?

The Third EGRET Catalog (3EG) lists 66 high-confidence identifications of sources with Active Galactic Nuclei (AGN). All are classified as belonging to the blazar class, with the only exception of the nearby radio galaxy Centaurus A. We report and strengthen the association of another radio galaxy, 3C111, with the EGRET source 3EG J0416+3650. At the time of the compilation of the 3EG catalogue, 3C111 has been considered as a low-confidence counterpart of 3EGJ0416+3650, being located outside the 99% gamma-ray probability contour. Since this first suggestion, no other counterparts have been reported nor the EGRET error box has been searched for likely candidates. 3C111 has never been considerated or cited in literature as a radiogalaxy counterpart of an EGRET source. We report a detailed multiwavelength study of the EGRET error box as well as for the first time the overall spectral energy distribution of 3C111, which appears to be intriguingly similar to those of blazars, suggesting that the radiogalaxy 3C111 is the likely counterpart of 3EG J0416+3650.Comment: 8 pages, 4 figure, 3 tables, accepted for publication in A&

Modelling Drosophila motion vision pathways for decoding the direction of translating objects against cluttered moving backgrounds

Decoding the direction of translating objects in front of cluttered moving backgrounds, accurately and efficiently, is still a challenging problem. In nature, lightweight and low-powered flying insects apply motion vision to detect a moving target in highly variable environments during flight, which are excellent paradigms to learn motion perception strategies. This paper investigates the fruit fly Drosophila motion vision pathways and presents computational modelling based on cuttingedge physiological researches. The proposed visual system model features bio-plausible ON and OFF pathways, wide-field horizontal-sensitive (HS) and vertical-sensitive (VS) systems. The main contributions of this research are on two aspects: (1) the proposed model articulates the forming of both direction-selective and direction-opponent responses, revealed as principalfeaturesofmotionperceptionneuralcircuits,inafeed-forwardmanner;(2)italsoshowsrobustdirectionselectivity to translating objects in front of cluttered moving backgrounds, via the modelling of spatiotemporal dynamics including combination of motion pre-filtering mechanisms and ensembles of local correlators inside both the ON and OFF pathways, which works effectively to suppress irrelevant background motion or distractors, and to improve the dynamic response. Accordingly, the direction of translating objects is decoded as global responses of both the HS and VS systems with positive ornegativeoutputindicatingpreferred-direction or null-direction translation.The experiments have verified the effectiveness of the proposed neural system model, and demonstrated its responsive preference to faster-moving, higher-contrast and larger-size targets embedded in cluttered moving backgrounds