scholarly journals Spike bursting in a dragonfly target-detecting neuron

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Joseph M. Fabian ◽  
Steven D. Wiederman
Keyword(s):  
Neuronal Responses ◽  
Moving Targets ◽  
Physiological Mechanisms ◽  
Visual Neurons ◽  
Neuronal Coding ◽  
Advantages And Disadvantages ◽  
Analysis Window ◽  
Neuronal Systems ◽  
Target Detecting ◽  
Spike Bursts

AbstractDragonflies visually detect prey and conspecifics, rapidly pursuing these targets via acrobatic flights. Over many decades, studies have investigated the elaborate neuronal circuits proposed to underlie this rapid behaviour. A subset of dragonfly visual neurons exhibit exquisite tuning to small, moving targets even when presented in cluttered backgrounds. In prior work, these neuronal responses were quantified by computing the rate of spikes fired during an analysis window of interest. However, neuronal systems can utilize a variety of neuronal coding principles to signal information, so a spike train’s information content is not necessarily encapsulated by spike rate alone. One example of this is burst coding, where neurons fire rapid bursts of spikes, followed by a period of inactivity. Here we show that the most studied target-detecting neuron in dragonflies, CSTMD1, responds to moving targets with a series of spike bursts. This spiking activity differs from those in other identified visual neurons in the dragonfly, indicative of different physiological mechanisms underlying CSTMD1’s spike generation. Burst codes present several advantages and disadvantages compared to other coding approaches. We propose functional implications of CSTMD1’s burst coding activity and show that spike bursts enhance the robustness of target-evoked responses.

scholarly journals The labile brain. II. Transients, complexity and selection

2000 ◽  
Vol 355 (1394) ◽  
pp. 237-252 ◽  
Author(s):  
Karl J. Friston
Keyword(s):  
Information Theory ◽  
Brain Function ◽  
Selective Pressure ◽  
Dynamic Instability ◽  
Point Of View ◽  
Brain Dynamics ◽  
Neuronal Responses ◽  
Dynamic Correlations ◽  
Neuronal Systems ◽  
Self Organizing

The successive expression of neuronal transients is related to dynamic correlations and, as shown in this paper, to dynamic instability. Dynamic instability is a form of complexity, typical of neuronal systems, which may be crucial for adaptive brain function from two perspectives. The first is from the point of view of neuronal selection and self–organizing systems: if selective mechanisms underpin the emergence of adaptive neuronal responses then dynamic instability is, itself, necessarily adaptive. This is because dynamic instability is the source of diversity on which selection acts and is therefore subject to selective pressure. In short, the emergence of order, through selection, depends almost paradoxically on the instabilities that characterize the diversity of brain dynamics. The second perspective is provided by information theory.

scholarly journals Simultaneous multi-area recordings suggest that attention improves performance by reshaping stimulus representations

2018 ◽  
Author(s):  
Douglas A. Ruff ◽  
Marlene R. Cohen
Keyword(s):  
Sensory Information ◽  
The Novel ◽  
Neuronal Responses ◽  
Visual Neurons ◽  
Neuronal Mechanisms ◽  
Oculomotor Neurons ◽  
Health And Disease ◽  
Neural Underpinnings ◽  
And Behavior ◽  
The Relationship

AbstractVisual attention dramatically improves subjects’ ability to see and also modulates the responses of neurons in every known visual and oculomotor area, but whether those modulations can account for perceptual improvements remains unclear. We measured the relationship between populations of visual neurons, oculomotor neurons, and behavior during detection and discrimination tasks. We found that neither of the two prominent hypothesized neuronal mechanisms underlying attention (which concern changes in information coding and the way sensory information is read out) provide a satisfying account of the observed behavioral improvements. Instead, our results are more consistent with the novel hypothesis that attention reshapes the representation of attended stimuli to more effectively influence behavior. Our results suggest a path toward understanding the neural underpinnings of perception and cognition in health and disease by analyzing neuronal responses in ways that are constrained by behavior and interactions between brain areas.

scholarly journals Dragonfly visual neurons selectively attend to features in naturalistic scenes

2020 ◽  
Author(s):  
BJE Evans ◽  
JM Fabian ◽  
DC O’Carroll ◽  
SD Wiederman
Keyword(s):  
Neuronal Response ◽  
Visual Presentation ◽  
Difficult Problem ◽  
Target Velocity ◽  
Natural Scenes ◽  
Moving Targets ◽  
Visual Neurons ◽  
Cluttered Environments ◽  
Preferred Direction ◽  
Background Motion

AbstractAerial predators, such as the dragonfly, determine the position and movement of their prey even when embedded in natural scenes. This task is likely supported by a group of optic lobe neurons with responses selective for moving targets of less than a few degrees. These Small Target Motion Detector (STMD) neurons are tuned to target velocity and show profound facilitation in responses to targets that move along continuous trajectories. When presented with a pair of targets, some STMDs competitively select one of the alternatives as if the other does not exist.Here we describe intracellular responses of STMD neurons to the visual presentation of many potential alternatives within cluttered environments comprised of natural scenes. We vary both target contrast and the background scene, across a range of target and background velocities. We find that background motion affects STMD responses indirectly, via the competitive selection of background features. We find that robust target discrimination is limited to scenarios when the target velocity is matched to, or greater than, background velocity. Furthermore, STMD target discriminability is modified by background direction. Backgrounds that move in the neuron’s anti-preferred direction result in the least performance degradation.Significance StatementBiological brains solve the difficult problem of visually detecting and tracking moving features in cluttered environments. We investigated this neuronal processing by recording intracellularly from dragonfly visual neurons that encode the motion of small moving targets subtending less than a few degrees (e.g. prey and conspecifics). However, dragonflies live in a complex visual environment where background features may interfere with tracking by reducing target contrast or providing competitive cues. We find that selective attention towards features drives much of the neuronal response, with background clutter competing with target stimuli for selection. Moreover, the velocity of features is an important component in determining the winner in these competitive interactions.

scholarly journals Real-Time Analysis of Athletes’ Physical Condition in Training Based on Video Monitoring Technology of Optical Flow Equation

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Cuijuan Wang
Keyword(s):  
Optical Flow ◽  
Physical Condition ◽  
Motion Segmentation ◽  
Motion Information ◽  
Moving Targets ◽  
Flow Equations ◽  
Advantages And Disadvantages ◽  
Template Update ◽  
Segmentation Algorithms ◽  
Multiple Frames

This article is dedicated to the research of video motion segmentation algorithms based on optical flow equations. First, some mainstream segmentation algorithms are studied, and on this basis, a segmentation algorithm for spectral clustering analysis of athletes’ physical condition in training is proposed. After that, through the analysis of the existing methods, compared with some algorithms that only process a single frame in the video, this article analyzes the continuous multiple frames in the video and extracts the continuous multiple frames of the sampling points through the Lucas-Kanade optical flow method. We densely sampled feature points contain as much motion information as possible in the video and then express this motion information through trajectory description and finally achieve segmentation of moving targets through clustering of motion trajectories. At the same time, the basic concepts of image segmentation and video motion target segmentation are described, and the division standards of different video motion segmentation algorithms and their respective advantages and disadvantages are analyzed. The experiment determines the initial template by comparing the gray-scale variance of the image, uses the characteristic optical flow to estimate the search area of the initial template in the next frame, reduces the matching time, judges the template similarity according to the Hausdorff distance, and uses the adaptive weighted template update method for the templates with large deviations. The simulation results show that the algorithm can achieve long-term stable tracking of moving targets in the mine, and it can also achieve continuous tracking of partially occluded moving targets.

scholarly journals Robust Master-Slave Synchronization of Neuronal Systems

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Hector Puebla ◽  
Eliseo Hernández-Martínez ◽  
Mariana Rodriguez-Jara ◽  
Cesar S. Lopez-Monsalvo
Keyword(s):  
Simple Structure ◽  
Model Uncertainties ◽  
Physiological Mechanisms ◽  
Control Engineering ◽  
Living Organisms ◽  
Neuronal Systems ◽  
Stimulation Of Nerve ◽  
The Brain ◽  
Insight Into ◽  
Gaining Insight

The desire to understand physiological mechanisms of neuronal systems has led to the introduction of engineering concepts to explain how the brain works. The synchronization of neurons is a central topic in understanding the behavior of living organisms in neurosciences and has been addressed using concepts from control engineering. We introduce a simple and reliable robust synchronization approach for neuronal systems. The proposed synchronization method is based on a master-slave configuration in conjunction with a coupling input enhanced with compensation of model uncertainties. Our approach has two nice features for the synchronization of neuronal systems: (i) a simple structure that uses the minimum information and (ii) good robustness properties against model uncertainties and noise. Two benchmark neuronal systems, Hodgkin-Huxley and Hindmarsh-Rose neurons, are used to illustrate our findings. The proposed synchronization approach is aimed at gaining insight into the effect of external electrical stimulation of nerve cells.

scholarly journals Visual attention mediated by biased competition in extrastriate visual cortex

1998 ◽  
Vol 353 (1373) ◽  
pp. 1245-1255 ◽  
Author(s):  
Robert Desimone
Keyword(s):  
Visual Field ◽  
Visual Attention ◽  
Spatial Location ◽  
Competitive Interactions ◽  
Extrastriate Cortex ◽  
Neuronal Responses ◽  
Top Down ◽  
Biased Competition ◽  
Enhancing Effect ◽  
Neuronal Systems

According to conventional neurobiological accounts of visual attention, attention serves to enhance extrastriate neuronal responses to a stimulus at one spatial location in the visual field. However, recent results from recordings in extrastriate cortex of monkeys suggest that any enhancing effect of attention is best understood in the context of competitive interactions among neurons representing all of the stimuli present in the visual field. These interactions can be biased in favour of behaviourally relevant stimuli as a result of many different processes, both spatial and non–spatial, and both bottom–up and top–down. The resolution of this competition results in the suppression of the neuronal representations of behaviourally irrelevant stimuli in extrastriate cortex. A main source of top–down influence may derive from neuronal systems underlying working memory.

Neuronal responses in the visual cortex of awake cats to stationary and moving targets

1971 ◽  
Vol 12 (4) ◽  
pp. 389-405 ◽  
Author(s):  
H. Noda ◽  
R. B. Freeman ◽  
B. Gies ◽  
O. D. Creutzfeldt
Keyword(s):  
Visual Cortex ◽  
Neuronal Responses ◽  
Moving Targets ◽  
Awake Cats

scholarly journals Help, there are ‘omics’ in my comparative physiology!

2020 ◽  
Vol 223 (24) ◽  
Author(s):  
Alex S. Torson ◽  
Yun-wei Dong ◽  
Brent J. Sinclair
Keyword(s):  
Time Scale ◽  
Experimental Designs ◽  
Comparative Physiology ◽  
Physiological Mechanisms ◽  
Advantages And Disadvantages ◽  
Simultaneous Measurements

Abstract ‘Omics’ methods, such as transcriptomics, proteomics, lipidomics or metabolomics, yield simultaneous measurements of many related molecules in a sample. These approaches have opened new opportunities to generate and test hypotheses about the mechanisms underlying biochemical and physiological phenotypes. In this Commentary, we discuss general approaches and considerations for successfully integrating omics into comparative physiology. The choice of omics approach will be guided by the availability of existing resources and the time scale of the process being studied. We discuss the use of whole-organism extracts (common in omics experiments on small invertebrates) because such an approach may mask underlying physiological mechanisms, and we consider the advantages and disadvantages of pooling samples within biological replicates. These methods can bring analytical challenges, so we describe the most easily analyzed omics experimental designs. We address the propensity of omics studies to digress into ‘fishing expeditions’ and show how omics can be used within the hypothetico-deductive framework. With this Commentary, we hope to provide a roadmap that will help newcomers approach omics in comparative physiology while avoiding some of the potential pitfalls, which include ambiguous experiments, long lists of candidate molecules and vague conclusions.

Cryogenic atomic force microscopy

1991 ◽  
Vol 49 ◽  
pp. 54-55
Author(s):  
K. A. Fisher ◽  
M. G. L. Gustafsson ◽  
M. B. Shattuck ◽  
J. Clarke
Keyword(s):  
Room Temperature ◽  
Rapid Freezing ◽  
Cryogenic Temperatures ◽  
Soft Or ◽  
Electrically Conductive ◽  
Force Microscopy ◽  
Flexible Molecules ◽  
Advantages And Disadvantages ◽  
Atomic Force ◽  
Chemical Perturbation

The atomic force microscope (AFM) is capable of imaging electrically conductive and non-conductive surfaces at atomic resolution. When used to image biological samples, however, lateral resolution is often limited to nanometer levels, due primarily to AFM tip/sample interactions. Several approaches to immobilize and stabilize soft or flexible molecules for AFM have been examined, notably, tethering coating, and freezing. Although each approach has its advantages and disadvantages, rapid freezing techniques have the special advantage of avoiding chemical perturbation, and minimizing physical disruption of the sample. Scanning with an AFM at cryogenic temperatures has the potential to image frozen biomolecules at high resolution. We have constructed a force microscope capable of operating immersed in liquid n-pentane and have tested its performance at room temperature with carbon and metal-coated samples, and at 143° K with uncoated ferritin and purple membrane (PM).

A conduction-cooled stage for high-resolution Cryo-SEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1282-1283
Author(s):  
John G. Sheehan
Keyword(s):  
High Resolution ◽  
Liquid Nitrogen ◽  
Mechanical Stability ◽  
Cooling System ◽  
Cold Trap ◽  
Nitrogen Gas ◽  
Particulate Suspensions ◽  
Advantages And Disadvantages ◽  
Convection Cooling ◽  
Styrene Butadiene

The goal is to examine with high resolution cryo-SEM aqueous particulate suspensions used in coatings for printable paper. A metal-coating chamber for cryo-preparation of such suspensions was described previously. Here, a new conduction-cooling system for the stage and cold-trap in an SEM specimen chamber is described. Its advantages and disadvantages are compared to a convection-cooling system made by Hexland (model CT1000A) and its mechanical stability is demonstrated by examining a sample of styrene-butadiene latex.In recent high resolution cryo-SEM, some stages are cooled by conduction, others by convection. In the latter, heat is convected from the specimen stage by cold nitrogen gas from a liquid-nitrogen cooled evaporative heat exchanger. The advantage is the fast cooling: the Hexland CT1000A cools the stage from ambient temperature to 88 K in about 20 min. However it consumes huge amounts of liquid-nitrogen and nitrogen gas: about 1 ℓ/h of liquid-nitrogen and 400 gm/h of nitrogen gas. Its liquid-nitrogen vessel must be re-filled at least every 40 min.

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