scholarly journals Ramp-to-Threshold Dynamics in a Hindbrain Population Controls the Timing of Spontaneous Saccades

2018 ◽  
Author(s):  
Alexandro D. Ramirez ◽  
Emre R.F. Aksay

SummaryOrganisms have the capacity to make decisions based solely on internal drives. However, it is unclear how neural circuits form decisions in the absence of sensory stimuli. Here we provide a comprehensive map of the activity patterns underlying the generation of saccades made in the absence of visual stimuli. We performed calcium imaging in the larval zebrafish to discover a range of responses surrounding spontaneous saccades, from cells that displayed tonic discharge only during fixations to neurons whose activity rose in advance of saccades by multiple seconds. We lesioned cells in these populations and found that ablation of neurons with pre-saccadic rise delayed saccade initiation. We analyzed spontaneous saccade initiation using a ramp-to-threshold model and were able to predict the times of upcoming saccades using pre-saccadic activity. These findings suggest that ramping of neuronal activity to a bound is a critical component of self-initiated saccadic movements.

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Alexandro D. Ramirez ◽  
Emre R. F. Aksay

AbstractOrganisms have the capacity to make decisions based solely on internal drives. However, it is unclear how neural circuits form decisions in the absence of sensory stimuli. Here we provide a comprehensive map of the activity patterns underlying the generation of saccades made in the absence of visual stimuli. We perform calcium imaging in the larval zebrafish to discover a range of responses surrounding spontaneous saccades, from cells that display tonic discharge only during fixations to neurons whose activity rises in advance of saccades by multiple seconds. When we lesion cells in these populations we find that ablation of neurons with pre-saccadic rise delays saccade initiation. We analyze spontaneous saccade initiation using a ramp-to-threshold model and are able to predict the times of upcoming saccades using pre-saccadic activity. These findings suggest that ramping of neuronal activity to a bound is a critical component of self-initiated saccadic movements.


2013 ◽  
Author(s):  
Frederick B. Shipley ◽  
Christopher M. Clark ◽  
Mark J. Alkema ◽  
Andrew M. Leifer

A fundamental goal of systems neuroscience is to probe the dynamics of neural activity that drive behavior. Here we present an instrument to simultaneously manipulate neural activity via Channelrhodopsin, monitor neural response via GCaMP3, and observes behavior in freely moving C. elegans. We use the instrument to directly observe the relation between sensory stimuli, interneuron activity and locomotion in the mechanosensory circuit. Now published as: Front Neural Circuits 8:28, doi:10.3389/fncir.2014.00028


2018 ◽  
Author(s):  
Suryadi ◽  
Ruey-Kuang Cheng ◽  
Suresh Jesuthasan ◽  
Lock Yue Chew

AbstractThe habenula is an evolutionarily conserved structure of the vertebrate brain that is essential for behavioural flexibility and mood control. It is spontaneously active and is able to access diverse states when the animal is exposed to sensory stimuli or reward. Here we analyze two-photon calcium imaging time-series of the habenula of larval zebrafish and find that percolation occurs, indicating the presence of long-range spatial correlations within each side of the habenula, with percolation occurring independently in each side. On the other hand, the analysis of neuronal avalanches suggests that the system is subcritical, implying that the flexibility in its dynamics may result from other dynamical processes.


Dharmakarya ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 145
Author(s):  
Lienda Noviyanti

As the times and technology became more sophisticated, human needs and mobility also increased. One such technology is vehicle. It cannot be denied that motorized vehicles and cars have now become the most important parts of everyday life. Vehicle protection is very important to keep vehicles safe, especially in areas prone to theft. Protection of the vehicle itself is divided into two ways, namely by personal and insurance methods. The fact is that vehicle protection carried out by Desa Sayang residents is still very minimal, which is caused by a lack of knowledge and understanding of citizens about the importance of vehicle protection. Seen from only a few residents who have insurance services to protect their vehicles. Measuring the perceptions of residents of RW 03 Desa Sayang, Jatinangor Subdistrict, Sumedang Regency is divided into 2 things, namely knowledge (cognition) and behavior (konasi). Of the 97 informants interviewed, it was found that people's knowledge of insurance was not good. While their knowledge of vehicle protection in general is quite good. In addition, vehicle ownership also affects individual knowledge of insurance and vehicle protection. Unfortunately, protection of vehicles in the form of insurance is rarely done by residents because most are hampered in terms of costs and feel they do not need it. Therefore, a perception survey and vehicle protection socialization were made in Sayang Village, Jatinangor Sub-District, Sumedang Regency so that residents would be more aware of maintaining their vehicles.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Hope J. Woods ◽  
Ming Fei Li ◽  
Ujas A. Patel ◽  
B. Duncan X. Lascelles ◽  
David R. Samson ◽  
...  

AbstractThe study of companion (pet) dogs is an area of great translational potential, as they share a risk for many conditions that afflict humans. Among these are conditions that affect sleep, including chronic pain and cognitive dysfunction. Significant advancements have occurred in the ability to study sleep in dogs, including development of non-invasive polysomnography; however, basic understanding of dog sleep patterns remains poorly characterized. The purpose of this study was to establish baseline sleep–wake cycle and activity patterns using actigraphy and functional linear modeling (FLM), for healthy, adult companion dogs. Forty-two dogs were enrolled and wore activity monitors for 14 days. FLM demonstrated a bimodal pattern of activity with significant effects of sex, body mass, and age; the effect of age was particularly evident during the times of peak activity. This study demonstrated that FLM can be used to describe normal sleep–wake cycles of healthy adult dogs and the effects of physiologic traits on these patterns of activity. This foundation makes it possible to characterize deviations from normal patterns, including those associated with chronic pain and cognitive dysfunction syndrome. This can improve detection of these conditions in dogs, benefitting them and their potential as models for human disease.


BMC Zoology ◽  
2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Karl Frafjord

Abstract Background Most temperate bats are regular hibernators in the winter. Knowledge about the length of their active season and how they adjust their nightly activity throughout the season, is critical to conservation. The characteristics of these are likely to vary with climate as well as latitude. This study investigated the flight activity of the soprano pipistrelle Pipistrellus pygmaeus in Frafjord, a small valley in the south-western corner of Norway (58° 50′N 6° 18′E) with an oceanic climate. Results Activity was recorded with an ultrasound recorder throughout April 2018 to June 2019 at one site, with supplemental recordings in March to June 2020, i.e., covering all months of the year. Recordings at other nearby sites were made in the summers (June–August) of 2016, 2017, 2019 and 2020, as well as some of the last days in December 2019 to the first days of January 2020. Overall, soprano pipistrelles were recorded flying in all months of the year, but very few in December–March. Regular activity was recorded from late April or early May until late October, and some recordings were also made in November. The highest numbers of recordings were made in August and September. Social calls, i.e. male song flights, were recorded from April to November, with the vast majority in August and September. Nearly all recordings were made between sunset and sunrise. Conclusions The soprano pipistrelle in this region showed regular activity through 6–7 months of the year. It adjusted its activity to the changing night length throughout the year, closely following sunset and sunrise. It was rarely recorded flying before sunset and almost never after sunrise. Most activity was recorded in the middle of the night, and social calls also followed this trend closely. Harems in late summer and autumn were confirmed in a bat box, which was also used for winter hibernation.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Joseph K. E. Ortega ◽  
Revathi P. Mohan ◽  
Cindy M. Munoz ◽  
Shankar Lalitha Sridhar ◽  
Franck J. Vernerey

AbstractThe sporangiophores of Phycomyces blakesleeanus have been used as a model system to study sensory transduction, helical growth, and to establish global biophysical equations for expansive growth of walled cells. More recently, local statistical biophysical models of the cell wall are being constructed to better understand the molecular underpinnings of helical growth and its behavior during the many growth responses of the sporangiophores to sensory stimuli. Previous experimental and theoretical findings guide the development of these local models. Future development requires an investigation of explicit and implicit assumptions made in the prior research. Here, experiments are conducted to test three assumptions made in prior research, that (a) elongation rate, (b) rotation rate, and (c) helical growth steepness, R, of the sporangiophore remain constant during the phototropic response (bending toward unilateral light) and the avoidance response (bending away from solid barriers). The experimental results reveal that all three assumptions are incorrect for the phototropic response and probably incorrect for the avoidance response but the results are less conclusive. Generally, the experimental results indicate that the elongation and rotation rates increase during these responses, as does R, indicating that the helical growth steepness become flatter. The implications of these findings on prior research, the “fibril reorientation and slippage” hypothesis, global biophysical equations, and local statistical biophysical models are discussed.


2019 ◽  
Vol 4 (1) ◽  
pp. 1-19
Author(s):  
Zarisnov Arafat ◽  
Muhammad Gary Gagarin Akbar

Ekstradisi secara universal hingga saat ini mengalami perubahan yang semakin baik, terutama setelah kehidupan bernegara sudah mulai tampak lebih maju sampai abad 20 ini. Hubungan dan pergaulan internasional menemukan bentuk dan substansinya yang baru dan berbeda dengan zaman sebelum Perjanjian Perdamaian Westphalia tahun 1648. Negara-negara yang berdasarkan atas prinsip kemerdekaan kedaulatan dan kedudukan sederajat mulai menata dirinya masing-masing terutama masalah domestik dengan membentuk dan mengembangkan hukum nasionalnya, yang salah satunya di bidang hukum pidana nasional. Hukum pidana nasional masing-masing negara, terutama jenis-jenis kejahatan atau tindak pidananya, disamping pula ada kesamaan dan perbedaannya. Semakin menguat batas wilayah dan kedaulatan teritorial masing-masing negara, semakin menguat pula penerapan hukum nasionalnya di dalam batas wilayah negara masing-masing. Semakin banyaknya perjanjian-perjanjian yang dibuat oleh negara-negara baik bilateral ataupun multilateral untuk mengatur suatu masalah tertentu yang sudah, sedang, dan akan dihadapi. Dalam pembuatan perjanjian tersebut mulai dilakukan pengkhususan atas substansinya, jadi tidak lagi satu perjanjian mencakup berbagai macam substansi yang berbeda-beda. Di Indonesia peraturan mengenai Ekstradisi dibuat pada tahun 1979, mengingat hingga saat ini belum terjadi perubahan di dalam Undang-Undang Nomor 1 Tahun 1979 padahal PBB telah membuat suatu model pembuatan perjanjian ekstradisi pada tahun 1990, sehingga sudah selayaknya peraturan mengenai ekstradisi di Indonesia harus mengalami pembaharuan ke depan yang lebih baik. Kata Kunci: Ekstradisi, Politik Hukum, Hukum Pidana.   Abstract Extradition is universally up to now experiencing increasingly good changes, especially after the state of life has begun to appear more advanced until the 20th century. International relations and relationships find new and different forms and substance from the times before the Treaty of Peace of Westphalia in 1648. Countries that are based on the principle of freedom of sovereignty and equal position begin to organize themselves, especially domestic problems by forming and developing national laws, which one of them is in the field of national criminal law. The national criminal law of each country, especially the types of crime or criminal acts, besides there are similarities and differences. The stronger regional boundaries and territorial sovereignty of each country, the stronger the application of national laws within the borders of each country. The increasing number of agreements made by countries both bilaterally and multilaterally to regulate a particular problem that has been, is being, and will be faced. In making these agreements, specialization of the substance began to be carried out, so no more than one agreement covers a variety of different substances. In Indonesia, the Extradition regulation was made in 1979, considering that until now there had been no changes in Law Number 1 of 1979 even though the United Nations had made a model for making an extradition treaty in 1990, so that proper regulations on extradition in Indonesia must undergo reform better future.                                   Keyword: Extradition, Politics of Law, The Criminal Law.                                                                        


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