scholarly journals Polarized Skylight Navigation in Insects: Model and Electrophysiology of e-Vector Coding by Neurons in the Central Complex

2008 ◽  
Vol 99 (2) ◽  
pp. 667-682 ◽  
Author(s):  
Midori Sakura ◽  
Dimitrios Lambrinos ◽  
Thomas Labhart
Keyword(s):  
Vision System ◽  
Gain Control ◽  
Central Complex ◽  
Degree Of Polarization ◽  
Insect Brain ◽  
Atmospheric Conditions ◽  
Compass Orientation ◽  
Vector Coding ◽  
Skylight Polarization ◽  
Vector Orientation

Many insects exploit skylight polarization for visual compass orientation or course control. As found in crickets, the peripheral visual system (optic lobe) contains three types of polarization-sensitive neurons (POL neurons), which are tuned to different (∼60° diverging) e-vector orientations. Thus each e-vector orientation elicits a specific combination of activities among the POL neurons coding any e-vector orientation by just three neural signals. In this study, we hypothesize that in the presumed orientation center of the brain (central complex) e-vector orientation is population-coded by a set of “compass neurons.” Using computer modeling, we present a neural network model transforming the signal triplet provided by the POL neurons to compass neuron activities coding e-vector orientation by a population code. Using intracellular electrophysiology and cell marking, we present evidence that neurons with the response profile of the presumed compass neurons do indeed exist in the insect brain: each of these compass neuron-like (CNL) cells is activated by a specific e-vector orientation only and otherwise remains silent. Morphologically, CNL cells are tangential neurons extending from the lateral accessory lobe to the lower division of the central body. Surpassing the modeled compass neurons in performance, CNL cells are insensitive to the degree of polarization of the stimulus between 99% and at least down to 18% polarization and thus largely disregard variations of skylight polarization due to changing solar elevations or atmospheric conditions. This suggests that the polarization vision system includes a gain control circuit keeping the output activity at a constant level.

scholarly journals Skylight Polarization patterns and Animal Orientation

1982 ◽  
Vol 96 (1) ◽  
pp. 69-91 ◽  
Author(s):  
MICHAEL L. BRINES ◽  
JAMES L. GOULD
Keyword(s):  
Rayleigh Scattering ◽  
Polarized Light ◽  
Processing System ◽  
Light Polarization ◽  
Degree Of Polarization ◽  
Atmospheric Conditions ◽  
Apparent Paradox ◽  
Skylight Polarization ◽  
Visible Wavelengths ◽  
Vector Orientation

1. Although many invertebrate animals orient by means of ultraviolet sky-light polarization patterns, existing measurements of these patterns are inadequate for full analysis of the biologically relevant information available from the sky. To fill this gap we have used a precision scanning polarimeter to measure simultaneously the intensity, degree, and direction of vibration (E-vector orientation) of polarized light at 5° intervals over the sky. The resulting sky maps were constructed for u.v. (350 nm) and visible wavelengths (500 and 650 nm) under a variety of atmospheric conditions. 2. Our measurements confirmed that the patterns of radiance and degree of polarization of skylight are highly variable and hence unreliable as orientation cues; but patterns of E-vector orientation are relatively stable and predictable over most of the sky under all but very hazy or overcast conditions. 3. The observed E-vector patterns correspond more closely to predictions based on first order (Rayleigh) scattering at 650 and 500 nm than at 350 nm. This is true both in terms of absolute accuracy and the proportion of the sky with relatively ‘correct’ information. Yet most insects respond to polarization patterns only at u.v. wavelengths. This apparent paradox can perhaps be resolved by assuming that there is no great selective advantage for any particular wavelength when large areas of blue sky are visible, but that under special and difficult conditions ultraviolet has advantages over longer wavelengths. Measurements under partially cloud-covered sky, for instance, or under extensive vegetation, show that both spuriously polarized and unpolarized light resulting from reflexions present more troublesome interference at longer wavelengths than in the u.v. 4. The accuracy of orientation achieved by dancing honey bees appears to be greater than can readily be accounted for by assuming that they use a strictly geometrical or analytical processing system for their orientation to polarized light.

scholarly journals Building a functional connectome of the Drosophila central complex

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Romain Franconville ◽  
Celia Beron ◽  
Vivek Jayaraman
Keyword(s):  
Light Microscopy ◽  
Critical Role ◽  
Central Complex ◽  
Connectivity Matrix ◽  
Insect Brain ◽  
Cell Type ◽  
Functional Connectome ◽  
Wide Range ◽  
Microscopy Images

The central complex is a highly conserved insect brain region composed of morphologically stereotyped neurons that arborize in distinctively shaped substructures. The region is implicated in a wide range of behaviors and several modeling studies have explored its circuit computations. Most studies have relied on assumptions about connectivity between neurons based on their overlap in light microscopy images. Here, we present an extensive functional connectome of Drosophila melanogaster’s central complex at cell-type resolution. Using simultaneous optogenetic stimulation, calcium imaging and pharmacology, we tested the connectivity between 70 presynaptic-to-postsynaptic cell-type pairs. We identified numerous inputs to the central complex, but only a small number of output channels. Additionally, the connectivity of this highly recurrent circuit appears to be sparser than anticipated from light microscopy images. Finally, the connectivity matrix highlights the potentially critical role of a class of bottleneck interneurons. All data are provided for interactive exploration on a website.

scholarly journals An ancestral apical brain region contributes to the central complex under the control offoxQ2in the beetleTribolium castaneum

2019 ◽  
Author(s):  
Bicheng He ◽  
Marita Buescher ◽  
Max Stephen Farnworth ◽  
Frederic Strobl ◽  
Ernst Stelzer ◽  
...  
Keyword(s):  
Gene Regulatory Network ◽  
Regulatory Network ◽  
Subsequent Development ◽  
Central Complex ◽  
Insect Brain ◽  
Neural Cells ◽  
Forkhead Transcription Factor ◽  
Marine Animals ◽  
Enhancer Trap Line ◽  
Gene Regulatory

AbstractThe genetic control of anterior brain development is highly conserved throughout animals. For instance, a conserved anterior gene regulatory network specifies the ancestral neuroendocrine center of animals and the apical organ of marine organisms. However, its contribution to the brain in non-marine animals has remained elusive. Here, we study the function of theTc-foxQ2forkhead transcription factor, a key regulator of the anterior gene regulatory network of insects. We characterized four distinct types ofTc-foxQ2positive neural progenitor cells based on differential co-expression withTc-six3/optix, Tc-six4, Tc-chx/vsx, Tc-nkx2.1/scro, Tc-ey, Tc-rxandTc-fez1. An enhancer trap line built by genome editing markedTc-foxQ2positive neurons, which projected through the primary brain commissure and later through a subset of commissural fascicles. Eventually, they contributed to the central complex. Strikingly, inTc-foxQ2RNAi knock-down embryos the primary brain commissure did not split and subsequent development of midline brain structures stalled. Our work establishesfoxQ2as a key regulator of brain midline structures, which distinguish the protocerebrum from segmental ganglia. Unexpectedly, our data suggest that the central complex evolved by integrating neural cells from an ancestral anterior neuroendocrine center.Summary statementAn ancestral neuroendocrine center contributes to the evolution of the central complex.foxQ2is a gene required for the development of midline structures of the insect brain, which distinguish protocerebrum from segmental ganglia.

scholarly journals Stimulus-dependent orientation strategies in monarch butterflies

2021 ◽  
Author(s):  
Myriam Franzke ◽  
Christian Kraus ◽  
Maria Gayler ◽  
David Dreyer ◽  
Keram Pfeiffer ◽  
...  
Keyword(s):  
Visual Cues ◽  
Danaus Plexippus ◽  
Monarch Butterfly ◽  
Central Complex ◽  
Orientation Behavior ◽  
Compass Orientation ◽  
Monarch Butterflies ◽  
Sun Compass ◽  
Bright Stripe ◽  
Flight Route

Insects are well-known for their ability to keep track of their heading direction based on a combination of skylight cues and visual landmarks. This allows them to navigate back to their nest, disperse throughout unfamiliar environments, as well as migrate over large distances between their breeding and non-breeding habitats. The monarch butterfly (Danaus plexippus) for instance is known for its annual southward migration from North America to certain trees in Central Mexico. To maintain a constant flight route, these butterflies use a time-compensated sun compass for orientation which is processed in a region in the brain, termed the central complex. However, to successfully complete their journey, the butterflies' brain must generate a multitude of orientation strategies, allowing them to dynamically switch from sun-compass orientation to a tactic behavior toward a certain target. To study if monarch butterflies exhibit different orientation modes and if they can switch between them, we observed the orientation behavior of tethered flying butterflies in a flight simulator while presenting different visual cues to them. We found that the butterflies' behavior depended on the presented visual stimulus. Thus, while a dark stripe was used for flight stabilization, a bright stripe was fixated by the butterflies in their frontal visual field. If we replaced a bright stripe by a simulated sun stimulus, the butterflies switched their orientation behavior and exhibited compass orientation. Taken together, our data show that monarch butterflies rely on and switch between different orientation modes, allowing them to adjust orientation to the actual behavioral demands of the animal.

scholarly journals A Novel Skylight Orientation Sensor for Autonomous Navigation

2021 ◽  
Author(s):  
Yuanyi Fan ◽  
Ran Zhang ◽  
Ze Liu ◽  
Jinkui Chu
Keyword(s):  
Autonomous Navigation ◽  
Symmetry Axis ◽  
Angle Measurement ◽  
Degree Of Polarization ◽  
Polarization Distribution ◽  
Reference Axis ◽  
Skylight Polarization ◽  
Application Potential ◽  
Orientation Sensor ◽  
Linear Polarizer

<a></a>The angle of the polarization (AOP) and the degree of polarization (DOP) of the scattered skylight are symmetrically distributed concerning the solar meridian. Based on the symmetry of the skylight polarization distribution pattern, this paper proposes a novel skylight orientation sensor consists of a camera, an S-waveplate, and a linear polarizer. The skylight orientation sensor is using the image polarization encoding capability of the S-waveplate and the linear polarizer to convert the skylight polarization information into the image’s symmetry axis extraction, which has the advantages of no resolution loss and instantaneous field of view error. The symmetry axis in the image is consistent with the solar meridian. Therefore, the angle between the solar meridian and the skylight orientation sensor reference axis can be obtained without calculating the polarization information, which is also beneficial for real-time performance. The angle measurement accuracy and uncertainty of the skylight orientation sensor are verified by numerical simulation and outdoor experiments. The results demonstrate that the skylight orientation sensor has good application potential in autonomous navigation.

Insect Navigation: Neural Basis to Behavior

2018 ◽  
Author(s):  
Stanley Heinze
Keyword(s):  
Path Integration ◽  
Sensory Information ◽  
Central Complex ◽  
Insect Brain ◽  
Head Direction ◽  
Neural Basis ◽  
Long Distance ◽  
Insect Navigation ◽  
Straight Line ◽  
Wide Range

Navigation is the ability of animals to move through their environment in a planned manner. Different from directed but reflex-driven movements, it involves the comparison of the animal’s current heading with its intended heading (i.e., the goal direction). When the two angles don’t match, a compensatory steering movement must be initiated. This basic scenario can be described as an elementary navigational decision. Many elementary decisions chained together in specific ways form a coherent navigational strategy. With respect to navigational goals, there are four main forms of navigation: explorative navigation (exploring the environment for food, mates, shelter, etc.); homing (returning to a nest); straight-line orientation (getting away from a central place in a straight line); and long-distance migration (seasonal long-range movements to a location such as an overwintering place). The homing behavior of ants and bees has been examined in the most detail. These insects use several strategies to return to their nest after foraging, including path integration, route following, and, potentially, even exploit internal maps. Independent of the strategy used, insects can use global sensory information (e.g., skylight cues), local cues (e.g., visual panorama), and idiothetic (i.e., internal, self-generated) cues to obtain information about their current and intended headings. How are these processes controlled by the insect brain? While many unanswered questions remain, much progress has been made in recent years in understanding the neural basis of insect navigation. Neural pathways encoding polarized light information (a global navigational cue) target a brain region called the central complex, which is also involved in movement control and steering. Being thus placed at the interface of sensory information processing and motor control, this region has received much attention recently and emerged as the navigational “heart” of the insect brain. It houses an ordered array of head-direction cells that use a wide range of sensory information to encode the current heading of the animal. At the same time, it receives information about the movement speed of the animal and thus is suited to compute the home vector for path integration. With the help of neurons following highly stereotypical projection patterns, the central complex theoretically can perform the comparison of current and intended heading that underlies most navigation processes. Examining the detailed neural circuits responsible for head-direction coding, intended heading representation, and steering initiation in this brain area will likely lead to a solid understanding of the neural basis of insect navigation in the years to come.

scholarly journals A visual pathway for skylight polarization processing in Drosophila

2020 ◽  
Author(s):  
Ben J. Hardcastle ◽  
Jaison J. Omoto ◽  
Pratyush Kandimalla ◽  
Bao-Chau M. Nguyen ◽  
Mehmet F. Keleş ◽  
...  
Keyword(s):  
Polarized Light ◽  
Fruit Fly ◽  
Visual Pathway ◽  
Central Complex ◽  
Reduced Representation ◽  
Central Processing ◽  
Use Patterns ◽  
Sense Of Direction ◽  
Skylight Polarization ◽  
Central Brain

SUMMARYMany insects use patterns of polarized light in the sky to orient and navigate. Here we functionally characterize neural circuitry in the fruit fly, Drosophila melanogaster, that conveys polarized light signals from the eye to the central complex, a brain region essential for the fly’s sense of direction. Neurons tuned to the angle of polarization of ultraviolet light are found throughout the anterior visual pathway, connecting the optic lobes with the central complex via the anterior optic tubercle and bulb, in a homologous organization to the ‘sky compass’ pathways described in other insects. We detail how a consistent, map-like organization of neural tunings in the peripheral visual system is transformed into a reduced representation suited to flexible processing in the central brain. This study identifies computational motifs of the transformation, enabling mechanistic comparisons of multisensory integration and central processing for navigation in the brains of insects.

Patterns of Skylight Polarization at Different Atmospheric Conditions

2011 ◽  
Vol 483 ◽  
pp. 770-774
Author(s):  
Yan Cui ◽  
Xiao Chen Zou ◽  
Jin Kui Chu ◽  
Qi Sheng Gao
Keyword(s):  
Spectral Range ◽  
Measurement System ◽  
Polarization Measurement ◽  
Cloud Layer ◽  
Atmospheric Conditions ◽  
Clear Sky ◽  
Atmospheric Turbidity ◽  
Skylight Polarization ◽  
Meteorologic Factors

A skylight polarization measurement system has been designed. With the measurement system, the patterns of skylight polarization measured at four kinds of atmospheric conditions at the spectral range 450~475 nm are presented. It is obvious that qualitatively the patterns of skylight polarization in sunny skies are in agreement with Rayleigh model. The stronger atmospheric turbidity, the greater disturbance to the patterns of skylight polarization appears in the atmosphere. The cloudy sky has terrible patterns of skylight polarization, this is mainly because it is overclouded and the sunlight is occluded completely. The degree of the skylight polarization P and the angle of the skylight polarization χ are the greatest in the clear sky. However, some meteorologic factors can disturb the polarized characteristics of skylight. Cloud layer and dust decrease P of skylight polarization and disturb χ of skylight polarization at different atmospheric conditions.

scholarly journals Matched-filter coding of sky polarization results in an internal sun compass in the brain of the desert locust

2020 ◽  
Vol 117 (41) ◽  
pp. 25810-25817
Author(s):  
Frederick Zittrell ◽  
Keram Pfeiffer ◽  
Uwe Homberg
Keyword(s):  
Spatial Orientation ◽  
Matched Filter ◽  
Polarized Light ◽  
Central Complex ◽  
Insect Brain ◽  
The Sun ◽  
Polarization Pattern ◽  
Sun Compass ◽  
Small Spot ◽  
Polarization Compass

Many animals use celestial cues for spatial orientation. These include the sun and, in insects, the polarization pattern of the sky, which depends on the position of the sun. The central complex in the insect brain plays a key role in spatial orientation. In desert locusts, the angle of polarized light in the zenith above the animal and the direction of a simulated sun are represented in a compass-like fashion in the central complex, but how both compasses fit together for a unified representation of external space remained unclear. To address this question, we analyzed the sensitivity of intracellularly recorded central-complex neurons to the angle of polarized light presented from up to 33 positions in the animal’s dorsal visual field and injected Neurobiotin tracer for cell identification. Neurons were polarization sensitive in large parts of the virtual sky that in some cells extended to the horizon in all directions. Neurons, moreover, were tuned to spatial patterns of polarization angles that matched the sky polarization pattern of particular sun positions. The horizontal components of these calculated solar positions were topographically encoded in the protocerebral bridge of the central complex covering 360° of space. This whole-sky polarization compass does not support the earlier reported polarization compass based on stimulation from a small spot above the animal but coincides well with the previously demonstrated direct sun compass based on unpolarized light stimulation. Therefore, direct sunlight and whole-sky polarization complement each other for robust head direction coding in the locust central complex.

scholarly journals Behavioural and physiological mechanisms of polarized light sensitivity in birds

2011 ◽  
Vol 366 (1565) ◽  
pp. 763-771 ◽  
Author(s):  
Rachel Muheim
Keyword(s):  
Physiological Mechanism ◽  
Polarized Light ◽  
Light Sensitivity ◽  
Convincing Evidence ◽  
Polarization Pattern ◽  
Compass Orientation ◽  
Receptor System ◽  
Sun Compass ◽  
Skylight Polarization ◽  
Compass Calibration

Polarized light (PL) sensitivity is relatively well studied in a large number of invertebrates and some fish species, but in most other vertebrate classes, including birds, the behavioural and physiological mechanism of PL sensitivity remains one of the big mysteries in sensory biology. Many organisms use the skylight polarization pattern as part of a sun compass for orientation, navigation and in spatial orientation tasks. In birds, the available evidence for an involvement of the skylight polarization pattern in sun-compass orientation is very weak. Instead, cue-conflict and cue-calibration experiments have shown that the skylight polarization pattern near the horizon at sunrise and sunset provides birds with a seasonally and latitudinally independent compass calibration reference. Despite convincing evidence that birds use PL cues for orientation, direct experimental evidence for PL sensitivity is still lacking. Avian double cones have been proposed as putative PL receptors, but detailed anatomical and physiological evidence will be needed to conclusively describe the avian PL receptor. Intriguing parallels between the functional and physiological properties of PL reception and light-dependent magnetoreception could point to a common receptor system.

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