scholarly journals Acute Application of Imidacloprid Alters the Sensitivity of Direction Selective Motion Detecting Neurons in an Insect Pollinator

2021 ◽  
Vol 12 ◽  
Author(s):  
Elisa Rigosi ◽  
David C. O’Carroll
Keyword(s):  
Flight Control ◽  
Visual Processing ◽  
Visual Cues ◽  
Visual Motion ◽  
Plant Protection ◽  
Control Treatment ◽  
Wide Field ◽  
General Effect ◽  
The Brain

Cholinergic pesticides, such as the neonicotinoid imidacloprid, are the most important insecticides used for plant protection worldwide. In recent decades, concerns have been raised about side effects on non-target insect species, including altered foraging behavior and navigation. Although pollinators rely on visual cues to forage and navigate their environment, the effects of neonicotinoids on visual processing have been largely overlooked. To test the effect of acute treatment with imidacloprid at known concentrations in the brain, we developed a modified electrophysiological setup that allows recordings of visually evoked responses while perfusing the brain in vivo. We obtained long-lasting recordings from direction selective wide-field, motion sensitive neurons of the hoverfly pollinator, Eristalis tenax. Neurons were treated with imidacloprid (3.9 μM, 0.39 μM or a sham control treatment using the solvent (dimethylsulfoxide) only. Exposure to a high, yet sub-lethal concentration of imidacloprid significantly alters their physiological response to motion stimuli. We observed a general effect of imidacloprid (3.9 μM) increasing spontaneous activity, reducing contrast sensitivity and giving weaker directional tuning to wide-field moving stimuli, with likely implications for errors in flight control, hovering and routing. Our electrophysiological approach reveals the robustness of the fly visual pathway against cholinergic perturbance (i.e., at 0.39 μM) but also potential threatening effects of cholinergic pesticides (i.e., evident at 3.9 μM) for the visual motion detecting system of an important pollinator.

scholarly journals The cholinergic pesticide imidacloprid impairs contrast and direction sensitivity in motion detecting neurons of an insect pollinator

2018 ◽  
Author(s):  
Elisa Rigosi ◽  
David C. O’Carroll
Keyword(s):  
Flight Control ◽  
Visual Processing ◽  
Visual Cues ◽  
Visual Motion ◽  
Plant Protection ◽  
Wide Field ◽  
Insect Pollinator ◽  
Direction Sensitivity ◽  
Spontaneous Firing Rate

AbstractCholinergic pesticides such as the neonicotinoid imidacloprid are the most important insecticides used for plant protection worldwide. In recent decades concerns have been raised about side effects on non-target insect species, including altered foraging behaviour and navigation. Although pollinators rely on visual cues to forage and navigate their environment, the effect of neonicotinoids on visual processing have been largely overlooked. Here we describe a modified electrophysiological setup that allowed recordings of visually evoked responses while perfusing the brain in vivo. Long-lasting recordings from wide-field motion sensitive neurons of the hoverfly pollinator, Eristalis tenax, revealed that sub-lethal exposure to imidacloprid alters their physiological response to motion stimuli. We observed substantially increased spontaneous firing rate, reduced contrast sensitivity and weaker directional tuning to wide-field moving stimuli. This approach reveals sub-lethal effects of imidacloprid in the visual motion detecting system of an important pollinator with likely implications for flight control, hovering and routing.

AN ANALOG VLSI INPLEMENTATION OF A VISUAL INTERNEURON: ENHANCED SENSORY PROCESSING THROUGH BIOPHYSICAL MODELING

1999 ◽  
Vol 09 (05) ◽  
pp. 391-395 ◽  
Author(s):  
REID R. HARRISON ◽  
CHRISTOF KOCH
Keyword(s):  
Sensory Processing ◽  
Visual Processing ◽  
Visual Motion ◽  
Gain Control ◽  
Analog Vlsi ◽  
Neuronal Model ◽  
Wide Field ◽  
Motion Information ◽  
Biophysical Modeling ◽  
Pattern Size

Flies are capable of rapid, coordinated flight through unstructured environments. This flight is guided by visual motion information that is extracted from photoreceptors in a robust manner. One feature of the fly's visual processing that adds to this robustness is the saturation of wide-field motion-sensitive neuron responses with increasing pattern size. This makes the cell's responses less dependent on the sparseness of the optical flow field while retaining motion information. By implementing a compartmental neuronal model in silicon, we add this "gain control" to an existing analog VLSI model of fly vision. This results in enhanced performance in a compact, low-power CMOS motion sensor. Our silicon system also demonstrates that modern, biophysically-detailed models of neural sensory processing systems can be instantiated in VLSI hardware.

scholarly journals Evaluation of two eco-friendly botanical extracts on fruit rot pathogens of orange (Citrus sinesis (L.) Osbeck)

2018 ◽  
Vol 10 (2) ◽  
pp. 107-112
Author(s):  
Thanh Toan Le ◽  
Trong Ky Vo ◽  
Huy Hoang Nguyen
Keyword(s):  
Aspergillus Niger ◽  
Plant Protection ◽  
Current Control ◽  
Fruit Rot ◽  
Alternative Methods ◽  
Control Treatment ◽  
Lesion Length ◽  
Leaf Extracts ◽  
Botanical Extracts

Fruit rot caused by Aspergillus niger and Colletotrichum sp. could cause rapid and severe damage on orange fruits. Current control method of orange fruits is mainly applied by usage of harmful pesticides, leading to chemical residues on fruits, environmental pollution and human poisoning. One of alternative methods of reducing pesticides is to use botanical extracts. This study was conducted to evaluate the in vivo antifungal efficacy of aqueous extracts from the leaves of neem and basket plants against A. niger and Colletotrichum sp. Orange fruits artificially inoculated by fruit rot pathogens were immersed into leaf extracts of 6% (w/v) neem or basket plants for 30 s, and kept for 11 days to record lesion length at room temperature. Orange fruits immersed into sterile distilled water were used as the control treatment. The results showed that at 11 days after inoculation, extracts of neem and basket plants significantly reduced the Aspergillus rot lesions by 109.08 and 124.00 mm, respectively. In addition, anthracnose lesions on orange fruits were statistically inhibited by treatments of neem and basket plants, with the average lesion diameters approximately 160.00 and 154.75 mm, respectively, at day 11 of the conducting experiment. The results of this study showed that leaf extracts of neem and basket plant at the concentration of 6% could be used as a natural alternative to control the in vivogrowth of rot pathogens of orange fruits. These extracts have a bright future in modern plant protection to replace conventional synthetic pesticides in agro-ecosystem. Thối trái bởi Aspergillus niger và Colletotrichum sp. gây ra các thiệt hại nghiêm trọng trên cam. Biện pháp phòng trừ bệnh trên trái cam hiện nay chủ yếu dựa vào thuốc hóa học, dẫn đến tồn dư thuốc trên trái cây, ô nhiễm môi trường và gây độc cho con người. Một trong các phương pháp thay thế giúp giảm sử dụng thuốc hóa học là sử dụng dịch trích thực vật. Nghiên cứu này đã được thưc hiện để đánh giá hiệu quả in vivo của dịch trích ở nồng độ 6% của neem hoặc lược vàng đối với A. niger và Colletotrichum sp. Các trái cam đã lây nhiễm nhân tạo tác nhân gây thối trái thì được nhúng vào dịch trích ở nồng độ 6% của neem hoặc lược vàng trong 30 giây, và giữ đến 11 ngày để ghi nhận chiều dài vết bệnh ở nhiệt độ phòng. Cái trái cam được nhúng vào nước cất thì dùng như nghiệm thức đối chứng. Kết quả cho thấy ở 11 ngày sau khi chủng bệnh, dịch trích neem và lược vàng làm giảm đáng kể vết thối Aspergillus lần lượt là 109,08 và 124,00 mm. Bên cạnh đó, vết bệnh thán thư trên trái cam đã bị ức chế có ý nghĩa thống kê bởi các dịch trích neem và lược vàng, với đường kính trung bình các vết bệnh lần lượt là 160,00 và 154,75 mm, ở ngày 11 của thí nghiệm. Kết quả của nghiên cứu này đã chỉ ra rằng dịch trích neem và lược vàng ở nồng độ 6% có thể sử dụng như một biện pháp thay thế tự nhiên trong việc phòng trừ sự phát triển của tác nhân gây thối trái cam. Các loại dịch trích này có tương lai trong bảo vệ thực vật hiện đại, thay thế các loại thuốc hóa học tổng hợp truyền thống trong hệ sinh thái nông nghiệp.

scholarly journals Disentangling of Local and Wide-Field Motion Adaptation

2021 ◽  
Vol 15 ◽  
Author(s):  
Jinglin Li ◽  
Miriam Niemeier ◽  
Roland Kern ◽  
Martin Egelhaaf
Keyword(s):  
Optic Flow ◽  
Visual Processing ◽  
Visual Motion ◽  
Spatial Scales ◽  
Stimulus Level ◽  
The Other ◽  
Wide Field ◽  
Local Motion ◽  
Motion Direction ◽  
Motion Adaptation

Motion adaptation has been attributed in flying insects a pivotal functional role in spatial vision based on optic flow. Ongoing motion enhances in the visual pathway the representation of spatial discontinuities, which manifest themselves as velocity discontinuities in the retinal optic flow pattern during translational locomotion. There is evidence for different spatial scales of motion adaptation at the different visual processing stages. Motion adaptation is supposed to take place, on the one hand, on a retinotopic basis at the level of local motion detecting neurons and, on the other hand, at the level of wide-field neurons pooling the output of many of these local motion detectors. So far, local and wide-field adaptation could not be analyzed separately, since conventional motion stimuli jointly affect both adaptive processes. Therefore, we designed a novel stimulus paradigm based on two types of motion stimuli that had the same overall strength but differed in that one led to local motion adaptation while the other did not. We recorded intracellularly the activity of a particular wide-field motion-sensitive neuron, the horizontal system equatorial cell (HSE) in blowflies. The experimental data were interpreted based on a computational model of the visual motion pathway, which included the spatially pooling HSE-cell. By comparing the difference between the recorded and modeled HSE-cell responses induced by the two types of motion adaptation, the major characteristics of local and wide-field adaptation could be pinpointed. Wide-field adaptation could be shown to strongly depend on the activation level of the cell and, thus, on the direction of motion. In contrast, the response gain is reduced by local motion adaptation to a similar extent independent of the direction of motion. This direction-independent adaptation differs fundamentally from the well-known adaptive adjustment of response gain according to the prevailing overall stimulus level that is considered essential for an efficient signal representation by neurons with a limited operating range. Direction-independent adaptation is discussed to result from the joint activity of local motion-sensitive neurons of different preferred directions and to lead to a representation of the local motion direction that is independent of the overall direction of global motion.

scholarly journals Differential adaptation to visual motion allows robust encoding of optic flow in the dragonfly

2018 ◽  
Author(s):  
Bernard J E Evans ◽  
David C O'Carroll ◽  
Joseph M Fabian ◽  
Steven D Wiederman
Keyword(s):  
Optic Flow ◽  
Visual Processing ◽  
Visual Motion ◽  
Slow Motion ◽  
Wide Field ◽  
Motion Adaptation ◽  
Early Visual Processing ◽  
Differential Adaptation ◽  
Analysis System ◽  
Great Complexity

An important task for any aerial creature is the ability to ascertain their own movement (ego-motion) through their environment. Neurons thought to underlie this behaviour have been well-characterised in many insect models including flies, moths and bees. However, dragonfly wide-field motion pathways remain undescribed. Some species of Dragonflies, such as Hemicordulia tau, engage in hawking behaviour, hovering in a single area for extended periods of time whilst also engaging in fast-moving patrols and highly dynamic pursuits of prey and conspecifics. These varied flight behaviours place very different constraints on establishing ego-motion from optic flow cues hinting at a sophisticated wide-field motion analysis system capable of detecting both fast and slow motion. We characterised wide-field motion sensitive neurons via intracellular recordings in Hemicordulia dragonflies finding similar properties to those found in other species. We found that the spatial and temporal tuning properties of these neurons were broadly similar but differed significantly in their adaptation to sustained motion. We categorised a total of three different subclasses, finding differences between subclasses in their motion adaptation and response to the broadband statistics of natural images. The differences found correspond well with the dynamics of the varied behavioural tasks hawking dragonflies perform. These findings may underpin the exquisite flight behaviours found in dragonflies. They also hint at the need for the great complexity seen in dragonfly early visual processing.

Effect of pH and inhibitors on beta-amyloid fibril assembly

1996 ◽  
Vol 54 ◽  
pp. 752-753
Author(s):  
Beverly E. Maleeff ◽  
Timothy K. Hart ◽  
Stephen J. Wood ◽  
Ronald Wetzel
Keyword(s):  
Amyloid Fibril ◽  
Peptide Fragment ◽  
Hydrophobic Peptides ◽  
Amyloid Fibril Formation ◽  
Effects Of Ph ◽  
Severity Of The Disease ◽  
Kinetics Of ◽  
The Brain

Alzheimer's disease is characterized post-mortem in part by abnormal extracellular neuritic plaques found in brain tissue. There appears to be a correlation between the severity of Alzheimer's dementia in vivo and the number of plaques found in particular areas of the brain. These plaques are known to be the deposition sites of fibrils of the protein β-amyloid. It is thought that if the assembly of these plaques could be inhibited, the severity of the disease would be decreased. The peptide fragment Aβ, a precursor of the p-amyloid protein, has a 40 amino acid sequence, and has been shown to be toxic to neuronal cells in culture after an aging process of several days. This toxicity corresponds to the kinetics of in vitro amyloid fibril formation. In this study, we report the biochemical and ultrastructural effects of pH and the inhibitory agent hexadecyl-N-methylpiperidinium (HMP) bromide, one of a class of ionic micellar detergents known to be capable of solubilizing hydrophobic peptides, on the in vitro assembly of the peptide fragment Aβ.

Microvascular features that suggest effectors of blood-flow regulation in the brain: Evidence by SEM of corrosion casts of intracerebral vessels

1990 ◽  
Vol 48 (3) ◽  
pp. 274-275
Author(s):  
Enrico D.F. Motti ◽  
Hans-Georg Imhof ◽  
Gazi M. Yasargil
Keyword(s):  
Blood Flow ◽  
Perfusion Pressure ◽  
Corrosion Casts ◽  
Cerebral Microcirculation ◽  
Pial Arteries ◽  
Random Occurrence ◽  
Brain Arteries ◽  
Homogeneous Network ◽  
The Brain

Physiologists have devoted most attention in the cerebrovascular tree to the arterial side of the circulation which has been subdivided in three levels: 1) major brain arteries which keep microcirculation constant despite changes in perfusion pressure; 2) pial arteries supposed to be effectors regulating microcirculation; 3) intracerebral arteries supposed to be deprived of active cerebral blood flow regulating devices.The morphological search for microvascular effectors in the cerebrovascular bed has been elusive. The opaque substance of the brain confines in vivo investigation to the superficial pial arteries. Most morphologists had to limit their observation to the random occurrence of a favorable site in the practically two-dimensional thickness of diaphanized histological sections. It is then not surprising most investigators of the cerebral microcirculation refer to an homogeneous network of microvessels interposed between arterioles and venules.We have taken advantage of the excellent depth of focus afforded by the scanning electron microscope (SEM) to investigate corrosion casts obtained injecting a range of experimental animals with a modified Batson's acrylic mixture.

Automated System for Epileptic Seizures Prediction based on Multi-Channel Recordings of Electrical Brain Activity

2018 ◽  
pp. 115-122 ◽  
Author(s):  
V. A. Maksimenko ◽  
A. A. Harchenko ◽  
A. Lüttjohann
Keyword(s):  
Epileptic Seizure ◽  
Brain Activity ◽  
Epileptic Seizures ◽  
Automated System ◽  
Brain Computer Interfaces ◽  
Electrical Brain Activity ◽  
Computer Interfaces ◽  
Prediction And Prevention ◽  
The Brain

Introduction: Now the great interest in studying the brain activity based on detection of oscillatory patterns on the recorded data of electrical neuronal activity (electroencephalograms) is associated with the possibility of developing brain-computer interfaces. Braincomputer interfaces are based on the real-time detection of characteristic patterns on electroencephalograms and their transformation  into commands for controlling external devices. One of the important areas of the brain-computer interfaces application is the control of the pathological activity of the brain. This is in demand for epilepsy patients, who do not respond to drug treatment.Purpose: A technique for detecting the characteristic patterns of neural activity preceding the occurrence of epileptic seizures.Results:Using multi-channel electroencephalograms, we consider the dynamics of thalamo-cortical brain network, preceded the occurrence of an epileptic seizure. We have developed technique which allows to predict the occurrence of an epileptic seizure. The technique has been implemented in a brain-computer interface, which has been tested in-vivo on the animal model of absence epilepsy.Practical relevance:The results of our study demonstrate the possibility of epileptic seizures prediction based on multichannel electroencephalograms. The obtained results can be used in the development of neurointerfaces for the prediction and prevention of seizures of various types of epilepsy in humans. 

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