A test for multiplication in insect directional motion detectors

1991 ◽  
Vol 331 (1260) ◽  
pp. 199-204 ◽  
Keyword(s):  
High Resolution ◽  
Stimulus Pattern ◽  
Optic Lobe ◽  
Large Field ◽  
Random Pattern ◽  
Motion Detector ◽  
Directional Response ◽  
Oscilloscope Screen ◽  
Directional Motion ◽  
Motion Detectors

The H1 neuron is a directionally sensitive motion-detector neuron with a large field that is fed by many high-resolution motion detectors in the fly optic lobe. As a stimulus pattern for it we used a random pattern of 50% bright and 50% dark squares on an oscilloscope screen. When this pattern is jumped by a small increment the HI neuron gives a directional response. When the jump is greater than one pixel on the screen the response falls and becomes non-directional because jump direction can no longer be inferred. When the contrast is reversed at the jump, the response is the same for both directions, and is the same as when the contrast is reversed without motion. For the motion receptors this represents a nondirectional ‘on’ or ‘off’ response. The result is discussed with reference to theories of motion perception.

scholarly journals Application of Airy beam light sheet microscopy to examine early neurodevelopmental structures in 3D hiPSC-derived human cortical spheroids

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Dwaipayan Adhya ◽  
George Chennell ◽  
James A. Crowe ◽  
Eva P. Valencia-Alarcón ◽  
James Seyforth ◽  
...  
Keyword(s):  
High Resolution ◽  
Human Brain ◽  
Light Sheet ◽  
Autism Spectrum ◽  
Model Systems ◽  
Large Field ◽  
Autism Spectrum Conditions ◽  
Patient Specific ◽  
Airy Beam

Abstract Background The inability to observe relevant biological processes in vivo significantly restricts human neurodevelopmental research. Advances in appropriate in vitro model systems, including patient-specific human brain organoids and human cortical spheroids (hCSs), offer a pragmatic solution to this issue. In particular, hCSs are an accessible method for generating homogenous organoids of dorsal telencephalic fate, which recapitulate key aspects of human corticogenesis, including the formation of neural rosettes—in vitro correlates of the neural tube. These neurogenic niches give rise to neural progenitors that subsequently differentiate into neurons. Studies differentiating induced pluripotent stem cells (hiPSCs) in 2D have linked atypical formation of neural rosettes with neurodevelopmental disorders such as autism spectrum conditions. Thus far, however, conventional methods of tissue preparation in this field limit the ability to image these structures in three-dimensions within intact hCS or other 3D preparations. To overcome this limitation, we have sought to optimise a methodological approach to process hCSs to maximise the utility of a novel Airy-beam light sheet microscope (ALSM) to acquire high resolution volumetric images of internal structures within hCS representative of early developmental time points. Results Conventional approaches to imaging hCS by confocal microscopy were limited in their ability to image effectively into intact spheroids. Conversely, volumetric acquisition by ALSM offered superior imaging through intact, non-clarified, in vitro tissues, in both speed and resolution when compared to conventional confocal imaging systems. Furthermore, optimised immunohistochemistry and optical clearing of hCSs afforded improved imaging at depth. This permitted visualization of the morphology of the inner lumen of neural rosettes. Conclusion We present an optimized methodology that takes advantage of an ALSM system that can rapidly image intact 3D brain organoids at high resolution while retaining a large field of view. This imaging modality can be applied to both non-cleared and cleared in vitro human brain spheroids derived from hiPSCs for precise examination of their internal 3D structures. This process represents a rapid, highly efficient method to examine and quantify in 3D the formation of key structures required for the coordination of neurodevelopmental processes in both health and disease states. We posit that this approach would facilitate investigation of human neurodevelopmental processes in vitro.

Solid-state VCSEL beam scanner with ultra-large field of view and high resolution

2021 ◽  
Author(s):  
Ruixiao Li ◽  
Zeuku Ho ◽  
Xiaodong Gu ◽  
Satoshi Shinada ◽  
Fumio Koyama
Keyword(s):  
Solid State ◽  
High Resolution ◽  
Field Of View ◽  
Large Field

Orthopteran DCMD neuron: a reevaluation of responses to moving objects. II. Critical cues for detecting approaching objects

1992 ◽  
Vol 68 (5) ◽  
pp. 1667-1682 ◽  
Author(s):  
P. J. Simmons ◽  
F. C. Rind
Keyword(s):  
Moving Objects ◽  
Optic Lobe ◽  
Receptive Fields ◽  
Wide Field ◽  
Motion Detector ◽  
Dark Light ◽  
Subsequent Response ◽  
Object Movement ◽  
Line Movement ◽  
Important Stimulus

1. We examine the critical image cues that are used by the locust visual system for the descending contralateral motion detector (DCMD) neuron to distinguish approaching from receding objects. Images were controlled by computer and presented on an electrostatic monitor. 2. Changes in overall luminance elicited much smaller and briefer responses from the DCMD than objects that appeared to approach the eye. Although a decrease in overall luminance might boost the response to an approaching dark object, movement of edges of the image is more important. 3. When two pairs of lines, in a cross-hairs configuration, were moved apart and then together again, the DCMD showed no preference for divergence compared with convergence of edges. A directional response was obtained by either making the lines increase in extent during divergence and decrease in extent during convergence; or by continually increasing the velocity of line movement during divergence and decreasing velocity during convergence. 4. The DCMD consistently gave a larger response to growing than to shrinking solid rectangular images. An increase compared with a decrease in the extent of edge in an image is, therefore, an important cue for the directionality of the response. For single moving edges of fixed extent, the neuron gave the largest response to edges that subtended 15 degrees at the eye. 5. The DCMD was very sensitive to the amount by which an edge traveled between frames on the display screen, with the largest responses generated by 2.5 degrees of travel. This implies that the neurons in the optic lobe that drive this movement-detecting system have receptive fields of about the same extent as a single ommatidium. 6. For edges moving up to 250 degree/s, the excitation of the DCMD increases with velocity. The response to an edge moving at a constant velocity adapts rapidly, in a manner that depends on velocity. Movement over one part of the retina can adapt the subsequent response to movement over another part of the retina. 7. For the DCMD to track and continue to respond to the image of an approaching object, the edges of the image must continually increase in velocity. This is the second important stimulus cue. 8. Edges of opposite contrasts (light-dark compared with dark-light) are processed in separate pathways that inhibit each other. This would contribute to the reduction of responses to wide-field movements.

The Best of Both Worlds: 3D X-ray Microscopy with Ultra-high Resolution and a Large Field of View

2011 ◽  
Author(s):  
W. Li ◽  
J. Gelb ◽  
Y. Yang ◽  
Y. Guan ◽  
W. Wu ◽  
...  
Keyword(s):  
High Resolution ◽  
Field Of View ◽  
Large Field ◽  
X Ray

scholarly journals Shadow monochromatic backlighting: Large-field high resolution X-ray shadowgraphy with improved spectral tunability

2001 ◽  
Vol 19 (2) ◽  
pp. 285-293 ◽  
Author(s):  
T.A. PIKUZ ◽  
A. YA. FAENOV ◽  
M. FRAENKEL ◽  
A. ZIGLER ◽  
F. FLORA ◽  
...  
Keyword(s):  
High Resolution ◽  
High Spatial Resolution ◽  
Field Of View ◽  
Large Field ◽  
X Ray ◽  
Traditional Scheme ◽  
Wide Range ◽  
Wide Wavelength Range ◽  
Bent Crystals ◽  
First Time

The shadow monochromatic backlighting (SMB) scheme, a modification of the well-known soft X-ray monochromatic backlighting scheme, is proposed. It is based on a spherical crystal as the dispersive element and extends the traditional scheme by allowing one to work with a wide range of Bragg angles and thus in a wide spectral range. The advantages of the new scheme are demonstrated experimentally and supported numerically by ray-tracing simulations. In the experiments, the X-ray backlighter source is a laser-produced plasma, created by the interaction of an ultrashort pulse, Ti:Sapphire laser (120 fs, 3–5 mJ, 1016 W/cm2 on target) or a short wavelength XeCl laser (10 ns, 1–2 J, 1013 W/cm2 on target) with various solid targets (Dy, Ni + Cr, BaF2). In both experiments, the X-ray sources are well localized spatially (∼20 μm) and are spectrally tunable in a relatively wide wavelength range (λ = 8–15 Å). High quality monochromatic (δλ/λ ∼ 10−5–10−3) images with high spatial resolution (up to ∼4 μm) over a large field of view (a few square millimeters) were obtained. Utilization of spherically bent crystals to obtain high-resolution, large field, monochromatic images in a wide range of Bragg angles (35° < Θ < 90°) is demonstrated for the first time.

Motion Detectors

2014 ◽  
pp. 290-310
Keyword(s):  
Visual Motion ◽  
Motion Sensors ◽  
Motion Detector ◽  
Security Systems ◽  
Intelligent Algorithms ◽  
Physical Motion ◽  
Security Personnel ◽  
Irregular Motion ◽  
Detection Capabilities ◽  
Motion Detectors

The first five sections represent the foundation and offer various intelligent algorithms that are the basics for motion detectors and their realization. There are two classes of security system alarm triggers: physical motion sensor and visual motion sensors. Both analog motion detectors and digital motion detectors belong to the group of visual motion sensors. Digital motion detector systems should differentiate between activities that are acceptable and those that breach security. When security-breaching acts occur, the system should identify the individuals and instruct security personnel what to do. Motion detectors can surveil, detect, and assess, as well as analyze information and distribute information to security personnel. Motion detector systems drastically reduce the load of footage that guards must watch for a long period of time. Automated motion detectors are now a standard for serious medium to large security installations; they are necessary for high detection capabilities. All security systems must have an alarming device to signal the guard of irregular motion in a scene, even systems that have a tiny or huge number of cameras.

Introduction to the Six Eye Movement Systems and the Visual Fixation System

2008 ◽  
Author(s):  
Agnes Wong
Keyword(s):  
Visual Acuity ◽  
Eye Movements ◽  
High Resolution ◽  
Information Overload ◽  
Survival Rates ◽  
Large Field ◽  
Field Of Vision ◽  
Very High Spatial Resolution ◽  
Different Characteristics ◽  
The Brain

One main reason that we make eye movements is to solve a problem of information overload. A large field of vision allows an animal to survey the environment for food and to avoid predators, thus increasing its survival rate. Similarly, a high visual acuity also increases survival rates by allowing an animal to aim at a target more accurately, leading to higher killing rates and more food. However, there are simply not enough neurons in the brain to support a visual system that has high resolution over the entire field of vision. Faced with the competing evolutionary demands for high visual acuity and a large field of vision, an effective strategy is needed so that the brain will not be overwhelmed by a large amount of visual input. Some animals, such as rabbits, give up high resolution in favor of a larger field of vision (rabbits can see nearly 360°), whereas others, such as hawks, restrict their field of vision in return for a high visual acuity (hawks have vision as good as 20/2, about 10 times better than humans). In humans, rather than using one strategy over the other, the retina develops a very high spatial resolution in the center (i.e., the fovea), and a much lower resolution in the periphery. Although this “foveal compromise” strategy solves the problem of information overload, one result is that unless the image of an object of interest happens to fall on the fovea, the image is relegated to the low-resolution retinal periphery. The evolution of a mechanism to move the eyes is therefore necessary to complement this foveal compromise strategy by ensuring that an object of interest is maintained or brought to the fovea. To maintain the image of an object on the fovea, the vestibulo-ocular (VOR) and optokinetic systems generate eye movements to compensate for head motions. Likewise, the saccadic, smooth pursuit, and vergence systems generate eye movements to bring the image of an object of interest on the fovea. These different eye movements have different characteristics and involve different parts of the brain.

The Culgoora Magnetograph

1971 ◽  
Vol 43 ◽  
pp. 24-29 ◽  
Author(s):  
J. V. Ramsay ◽  
R. G. Giovanelli ◽  
H. R. Gillett
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Angular Resolution ◽  
Field Of View ◽  
Large Field ◽  
Sensitive Line ◽  
The One ◽  
The Magnetic Field

The magnetograph is based on a high-resolution filter which serves in place of a spectrograph, except that a reasonably large field of view (one-quarter of the Sun's diameter) can be observed at the one instant. Observations are made by obtaining filtergrams of opposite circular polarizations simultaneously in the wing of a magnetically sensitive line. Exposure times are about 0.3 s, the angular resolution of the magnetic field is about 2 arc s, closest frame repetition rates about 8 s. The filtergrams are processed subsequently by photographic or television subtraction. Semiautomatic photographic and/or TV subtractions yield magnetograms suitable for cinematographic projection though the subtractions are not yet as perfect as those obtained by individual subtraction.

Non-directional motion detectors can be used to mimic optic flow dependent behaviors

2010 ◽  
Vol 103 (6) ◽  
pp. 433-446 ◽  
Author(s):  
Jonathan P. Dyhr ◽  
Charles M. Higgins
Keyword(s):  
Optic Flow ◽  
Directional Motion ◽  
Motion Detectors
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