Browsing by Subject "Motion detection"
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Item Open Access Fizik tedavi egzersizlerinin giyilebilir hareket algılayıcıları işaretlerinden dinamik zaman bükmesiyle sezimi ve değerlendirilmesi(IEEE, 2014-04) Yurtman, Aras; Barshan, BillurGiyilebilir hareket algılayıcılarından kaydedilen sinyalleri işleyerek fizik tedavi egzersizlerini algılamak ve değerlendirmek için özerk bir sistem geliştirilmiştir. Bir fizik tedavi seansındaki bir ya da birden fazla egzersiz tipini algılamak için, temeli dinamik zaman bükmesi (DZB) benzeşmezlik ölçütüne dayanan bir algoritma geliştirilmiştir. Algoritma, egzersizlerin doğru ya da yanlış yapıldığını değerlendirmekte ve varsa hata türünü saptamaktadır. Algoritmanın başarımını degerlendirmek için, beş katılımcı tarafından yapılan sekiz egzersiz hareketinin üç yürütüm türü için birer şablon ve 10’ar sınama yürütümünden oluşan bir veri kümesi kaydedilmiştir. Dolayısıyla, eğitim ve sınama kümelerinde sırasıyla 120 ve 1,200 egzersiz yürütümü bulunmaktadır. Sınama kümesi, boş zaman dilimleri de içermektedir. Öne sürülen algoritma, sınama kümesindeki 1,200 yürütümün % 8.58’ini kaçırmakta ve boş zaman dilimlerinin % 4.91’ini yanlış sezim olarak değerlendirerek toplam 1,125 yürütüm algılamaktadır. Doğruluk, sadece egzersiz sınıflandırması ele alındığında ˘ % 93.46, hem egzersiz hem de yürütüm türü sınıflandırması içinse % 88.65’tir. Sistemin bilinmeyen egzersizlere karşı davranışını sınamak için, algoritma, her egzersiz için, o egzersizin şablonları dışarıda bırakılarak çalıştırılmış ve 1,200 egzersizin sadece 10’u yanlış sezilmiştir. Bu sonuç, sistemin bilinmeyen hareketlere karşı gürbüz olduğunu göstermektedir. Öne sürülen sistem, hem bir fizik tedavi seansının yoğunluğunu kestirmek, hem de hastaya ve fizik tedavi uzmanına geribildirim vermek amacıyla egzersiz hareketlerini değerlendirmek için kullanılabilir.Item Open Access Investigating motion detection of aging zebrafish with optomotor response(Bilkent University, 2021-07) Karaduman, AyşenurVarious aspects of visual functioning including motion perception have been shown to be significantly altered throughout aging. Contrary to the traditional view focusing on structural changes in the eye and retina, accumulating evidence suggests that subtle alterations in neural circuitry and functioning are respon-sible for the age-related changes in visual sensitivity and perception. However, the mechanisms underlying age-related changes in motion perception are still poorly understood. This thesis was aimed to investigate the detection of first-and second-order motion direction during aging by using zebrafish optomotor re-sponses (OMR). Furthermore, exposure-based visual learning was investigated by repeated presentation of first-order motion. The studies included both wild-type and achesb55/+ zebrafish with decreased levels of acetylcholinesterase which has been previously shown to delay age-related cognitive decline. In this way, it was also aimed to explore the possible functional links between cholinergic functioning and age-related changes in visual motion processing. The results indicated that adult zebrafish mainly exhibit negative OMR (i.e., position shift in the opposite direction of visual motion) to drifting first-order gratings which is significantly dependent on spatial frequency and contrast level of the motion. Rather than an overall effect of aging, the results revealed a three-way interaction between the contrast level of first-order motion, genotype, and age. Therefore, the findings pointed out a complex relationship between the physical characteristics of first-order motion stimulation and the cholinergic system during neural aging. Contrary to the first-order motion, the second-order motion did not induce strong optomotor responses in adult zebrafish. Although young and old zebrafish exhibited OMR with different polarities (negative and positive OMR, respectively), future work revealing robust responses will be informative to better understand and characterize age-related changes. Lastly, passive exposure of repeated first-order motion induced significant improvements in negative OMR of young and old zebrafish, suggesting that adult zebrafish can be used as a model organism to study passive forms of visual perceptual learning. Overall, these behavioral results pave the way for a detailed investigation of the functional links between the physical motion characteristics and the cholinergic system in the zebrafish aging model which will ultimately have important implications for developing interventions to improve human visual performance during aging.Item Open Access Magnocellular based visual motion training improves reading in Persian(Nature Publishing Group, 2019-02) Ebrahimi, L.; Pouretemad, H.; Khatibi, Ali; Stein, J.The visual magnocellular system is thought to play a crucial role in learning to read. Here therefore, we examined whether magnocellular based training could improve reading in children with visual reading problems. The participants were 24 male primary school students aged between 9–11 (Mean = 9.76, SD = 0.59) with specific reading difficulty. Experimental and control groups were matched for age, sex, educational level, IQ, reading abilities (measured by APRA), magnocellular performance as assessed by a random dot kinematogram (RDK) paradigm and recordings of their saccadic eye movements. The experimental group received twelve magnocellular based visual motion training sessions, twice a week over 6 weeks. During the same period, the control group played a video game with the help of a practitioner. All measures were made just prior to the training and were repeated at the 6th, 12th training session and one month later. The experimental group showed significant improvements in magnocellular function, visual errors and reading accuracy during the course of intervention. Follow-up assessment confirmed that these effects persisted one month later. Impaired magnocellular functioning appeared to be an important cause of poor reading in Persian. Hence magnocellular based training could help many children with specific reading difficulties. Also testing magnocellular function could be used as screening tool for detecting dyslexia before a child begins to fail at school.Item Open Access Moving region detection in compressed video(Springer, 2004) Töreyin, B. U.; Çetin, A. Enis; Aksay, A.; Akhan, M. B.In this paper, an algorithm for moving region detection in compressed video is developed. It is assumed that the video can be compressed either using the Discrete Cosine Transform (DOT) or the Wavelet Transform (WT). The method estimates the WT of the background scene from the WTs of the past image frames of the video. The WT of the current image is compared with the WT of the background and the moving objects are determined from the difference. The algorithm does not perform inverse WT to obtain the actual pixels of the current image nor the estimated background. In the case of DOT compressed video, the DC values of 8 by 8 image blocks of Y, U and V channels are used for estimating the background scene. This leads to a computationally efficient method and a system compared to the existing motion detection methods. © Springer-Verlag 2004.Item Open Access The optomotor response of aging zebrafish reveals a complex relationship between visual motion characteristics and cholinergic system(Elsevier, 2020-10-23) Karaduman, Ayşenur; Karoğlu-Eravşar, Elif Tuğçe; Kaya, Utku; Aydın, Alaz; Adams, Michelle; Kafalıgönül, HulusiUnderstanding the principles underlying age-related changes in motion perception is paramount for improving the quality of life and health of older adults. However, the mechanisms underlying age-related alterations in this aspect of vision, which is essential for survival in a dynamic world, still remain unclear. Using optomotor responses to drifting gratings, we investigated age-related changes in motion detection of adult zebrafish (wild-type/AB-strain and achesb55/+ mutants with decreased levels of acetylcholinesterase). Our results pointed out negative optomotor responses that significantly depend on the spatial frequency and contrast level of stimulation, providing supporting evidence for the visual motion-driven aspect of this behavior mainly exhibited by adult zebrafish. Although there were no significant main effects of age and genotype, we found a significant three-way interaction between contrast level, age, and genotype. In the contrast domain, the changes in optomotor responses and thus in the detection of motion direction were age- and genotype-specific. Accordingly, these behavioral findings suggest a strong but complicated relationship between visual motion characteristics and the cholinergic system during neural aging.Item Open Access Passive exposure to visual motion leads to short-term changes in the optomotor response of aging zebrafish(Cambridge University Press, 2024-03) Karaduman, Ayşenur; Karaoğlu-Eravşar, Elif Tuğçe; Adams, Michelle M.; Kafalıgönül, HulusiNumerous studies have shown that prior visual experiences play an important role in sensory processing and adapting behavior in a dynamic environment. A repeated and passive presentation of visual stimulus is one of the simplest procedures to manipulate acquired experiences. Using this approach, we aimed to investigate exposure- based visual learning of aging zebrafish and how cholinergic intervention is involved in exposure-induced changes. Our measurements included younger and older wild-type zebrafish and achesb55/+mutants with decreased acetylcholinesterase activity. We examined both within-session and across-day changes in the zebrafish optomotor responses to repeated and passive exposure to visual motion. Our findings revealed short- term (within-session) changes in the magnitude of optomotor response (i.e., the amount of position shift by fish as a response to visual motion) rather than long-term and persistent effects across days. Moreover, the observed short-term changes were age- and genotype-dependent. Compared to the initial presentations of motion within a session, the magnitude of optomotor response to terminal presentations decreased in the older zebrafish. There was a similar robust decrease specific to achesb55/+mutants. Taken together, these results point to short- term (within-session) alterations in the motion detection of adult zebrafish and suggest differential effects of neural aging and cholinergic system on the observed changes. These findings further provide important insights into adult zebrafish optomotor response to visual motion and contribute to understanding this reflexive behavior in the short- and long-term stimulation profiles.Item Embargo Zebrafish optomotor response to second-order motion illustrates that age-related changes in motion detection depend on the activated motion system(Elsevier Inc., 2023-06-10) Karaduman, Ayşenur; Karoğlu-Eravşar, Elif Tuğçe; Kaya, Utku; Aydın, Alaz; Adams, Michelle Marie; Kafalıgönül, HulusiVarious aspects of visual functioning, including motion perception, change with age. Yet, there is a lack of comprehensive understanding of age-related alterations at different stages of motion processing and in each motion system. To understand the effects of aging on second-order motion processing, we investigated optomotor responses (OMR) in younger and older wild-type (AB-strain) and acetylcholinesterase (achesb55/+) mutant zebrafish. The mutant fish with decreased levels of acetylcholinesterase have been shown to have delayed age-related cognitive decline. Compared to previous results on first-order motion, we found distinct changes in OMR to second-order motion. The polarity of OMR was dependent on age, such that second-order stimulation led to mainly negative OMR in the younger group while older zebrafish had positive responses. Hence, these findings revealed an overall aging effect on the detection of second-order motion. Moreover, neither the genotype of zebrafish nor the spatial frequency of motion significantly changed the response magnitude. Our findings support the view that age-related changes in motion detection depend on the activated motion system. © 2023 Elsevier Inc.