scholarly journals A new, fluorescence-based method for visualizing the pseudopupil and assessing optical acuity in the dark compound eyes of honeybees and other insects

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Elisa Rigosi ◽  
Eric J. Warrant ◽  
David C. O’Carroll
Keyword(s):  
Fluorescent Dyes ◽  
Imaging Techniques ◽  
Optical Resolution ◽  
Gaze Direction ◽  
Dark Spot ◽  
Compound Eyes ◽  
The Gaze ◽  
Recent Interest ◽  
Frontal Part ◽  
Direct Measures

AbstractRecent interest in applying novel imaging techniques to infer optical resolution in compound eyes underscores the difficulty of obtaining direct measures of acuity. A widely used technique exploits the principal pseudopupil, a dark spot on the eye surface representing the ommatidial gaze direction and the number of detector units (ommatidia) viewing that gaze direction. However, dark-pigmented eyes, like those of honeybees, lack a visible pseudopupil. Attempts over almost a century to estimate optical acuity in this species are still debated. Here, we developed a method to visualize a stable, reliable pseudopupil by staining the photoreceptors with fluorescent dyes. We validated this method in several species and found it to outperform the dark pseudopupil for this purpose, even in pale eyes, allowing more precise location of the gaze centre. We then applied this method to estimate the sampling resolution in the frontal part of the eye of the honeybee forager. We found a broad frontal acute zone with interommatidial angles below 2° and a minimum interommatidial angle of 1.3°, a broader, sharper frontal acute zone than previously reported. Our study provides a new method to directly measure the sampling resolution in most compound eyes of living animals.

scholarly journals Surgical Advances in Osteosarcoma

Cancers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 388
Author(s):  
Marcus J. Brookes ◽  
Corey D. Chan ◽  
Bence Baljer ◽  
Sachin Wimalagunaratna ◽  
Timothy P. Crowley ◽  
...  
Keyword(s):  
Fluorescent Dyes ◽  
Imaging Techniques ◽  
Intraoperative Imaging ◽  
Survival Rates ◽  
Computer Navigation ◽  
Bone Cancer ◽  
Technical Difficulty ◽  
Implant Design ◽  
Patient Specific ◽  
Patient Specific Instruments

Osteosarcoma (OS) is the most common primary bone cancer in children and, unfortunately, is associated with poor survival rates. OS most commonly arises around the knee joint, and was traditionally treated with amputation until surgeons began to favour limb-preserving surgery in the 1990s. Whilst improving functional outcomes, this was not without problems, such as implant failure and limb length discrepancies. OS can also arise in areas such as the pelvis, spine, head, and neck, which creates additional technical difficulty given the anatomical complexity of the areas. We reviewed the literature and summarised the recent advances in OS surgery. Improvements have been made in many areas; developments in pre-operative imaging technology have allowed improved planning, whilst the ongoing development of intraoperative imaging techniques, such as fluorescent dyes, offer the possibility of improved surgical margins. Technological developments, such as computer navigation, patient specific instruments, and improved implant design similarly provide the opportunity to improve patient outcomes. Going forward, there are a number of promising avenues currently being pursued, such as targeted fluorescent dyes, robotics, and augmented reality, which bring the prospect of improving these outcomes further.

External Design and Field of View of the Compound Eyes in a Raptorial Neuropteran Insect, Mantispa Styriaca

1990 ◽  
Vol 148 (1) ◽  
pp. 353-365 ◽  
Author(s):  
U. EGGENREICH ◽  
K. KRAL
Keyword(s):  
Dark Adaptation ◽  
Visual Fields ◽  
Field Of View ◽  
Compound Eyes ◽  
Praying Mantis ◽  
Binocular Field ◽  
Frontal Part

Visual fields and ommatidial angles of the compound eyes of Mantispa styriaca were determined using luminous pseudopupil and histological-anatomical techniques. The maximal horizontal overlap averaged 42.7° in femalesand 52.4° in males; females had only one overlap maximum, whereas males had two. In the dorsoventral direction, the binocular field had an overlap of 135.2° in the female and 142° in the male. In light-adapted eyes, optical acceptance angles reached values of 2.0°, and they reached 3.6° with dark adaptation; interommatidial angles were between 1.8° and 2.3°. The angles were very similar over the entire eye; no acute zone was found in the frontal part of the eye, as the large binocular overlap would suggest. The results are compared with those for the praying mantis: this animal is in no way related to Mantispa but resembles it in appearance and capture behaviour.

scholarly journals Fear-specific leftward bias in gaze direction judgment

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yue Zhang ◽  
Qiqi Hu ◽  
Xinwei Lai ◽  
Zhonghua Hu ◽  
Shan Gao
Keyword(s):  
Judgment Task ◽  
Gaze Direction ◽  
Emotional Information ◽  
Cerebral Lateralization ◽  
Low Level ◽  
The Gaze ◽  
Fearful Faces ◽  
Perception Bias ◽  
Behavioural Experiments ◽  
Direction Judgment

AbstractPrevious studies have shown that humans have a left spatial attention bias in cognition and behaviour. However, whether there exists a leftward perception bias of gaze direction has not been investigated. To address this gap, we conducted three behavioural experiments using a forced-choice gaze direction judgment task. The point of subjective equality (PSE) was employed to measure whether there was a leftward perception bias of gaze direction, and if there was, whether this bias was modulated by face emotion. The results of experiment 1 showed that the PSE of fearful faces was significantly positive as compared to zero and this effect was not found in angry, happy, and neutral faces, indicating that participants were more likely to judge the gaze direction of fearful faces as directed to their left-side space, namely a leftward perception bias. With the response keys counterbalanced between participants, experiment 2a replicated the findings in experiment 1. To further investigate whether the gaze direction perception variation was contributed by emotional or low-level features of faces, experiment 2b and 3 used inverted faces and inverted eyes, respectively. The results revealed similar leftward perception biases of gaze direction in all types of faces, indicating that gaze direction perception was biased by emotional information in faces rather than low-level facial features. Overall, our study demonstrates that there a fear-specific leftward perception bias in processing gaze direction. These findings shed new light on the cerebral lateralization in humans.

scholarly journals What is unique about the human eye? Comparative image analysis on the external eye morphology of human and nonhuman great apes

2021 ◽  
Author(s):  
Fumihiro Kano ◽  
Takeshi Furuichi ◽  
Chie Hashimoto ◽  
Christopher Krupenye ◽  
Jesse G Leinwand ◽  
...  
Keyword(s):  
Image Analysis ◽  
Eye Gaze ◽  
Great Apes ◽  
Gaze Direction ◽  
Human Eye ◽  
The Gaze ◽  
Eye Morphology ◽  
New Findings ◽  
Heated Debate ◽  
Signaling Hypothesis

The gaze-signaling hypothesis and the related cooperative-eye hypothesis posit that humans have evolved special external eye morphology, including exposed white sclera (the white of the eye), to enhance the visibility of eye-gaze direction and thereby facilitate conspecific communication through joint-attentional interaction and ostensive communication. However, recent quantitative studies questioned these hypotheses based on new findings that humans are not necessarily unique in certain eye features compared to other great ape species. Therefore, there is currently a heated debate on whether external eye features of humans are distinguished from those of other apes and how such distinguished features contribute to the visibility of eye-gaze direction. This study leveraged updated image analysis techniques to test the uniqueness of human eye features in facial images of great apes. Although many eye features were similar between humans and other species, a key difference was that humans have uniformly white sclera which creates clear visibility of both eye outline and iris; the two essential features contributing to the visibility of eye-gaze direction. We then tested the robustness of the visibility of these features against visual noises such as darkening and distancing and found that both eye features remain detectable in the human eye, while eye outline becomes barely detectable in other species under these visually challenging conditions. Overall, we identified that humans have distinguished external eye morphology among other great apes, which ensures robustness of eye-gaze signal against various visual conditions. Our results support and also critically update the central premises of the gaze-signaling hypothesis.

How Neurons Communicate: Gap Junctions and Neurosecretion

The Neuron ◽  
2015 ◽  
pp. 153-186
Author(s):  
Irwin B. Levitan ◽  
Leonard K. Kaczmarek
Keyword(s):  
Synaptic Vesicles ◽  
Fluorescent Dyes ◽  
Imaging Techniques ◽  
Electrical Coupling ◽  
Snare Complex ◽  
Biologically Active ◽  
Nerve Terminals ◽  
Capacitance Measurements ◽  
Complex Process ◽  
Cytoplasmic Vesicles

Two ways that neurons communicate with one another are by direct electrical coupling and by the secretion of neurotransmitters. Electrical coupling arises from the existence of proteins, known as connexins, that form pores linking the cytoplasm of adjacent cells. Ions and small molecules can carry signals from one cell to another through these pores. Neurosecretion is a more complex process whereby different categories of molecules are sorted into cytoplasmic vesicles. Chemical processes within these vesicles ensure that they contain biologically active transmitters or hormones. SNARE complex proteins cooperate with other proteins to allow synaptic vesicles containing neurotransmitter to release their components into the external medium following calcium entry into nerve terminals. Such exocytosis of synaptic vesicles can be monitored with imaging techniques using fluorescent dyes or proteins, or by capacitance measurements. A second set of molecules retrieves the membrane of synaptic vesicles back from the plasma membrane through endocytosis.

Effects of Gaze Direction in Vision and Audition

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 137-137
Author(s):  
W H Ehrenstein ◽  
J Lewald ◽  
L Schlykowa
Keyword(s):  
Visual Cues ◽  
Posterior Parietal Cortex ◽  
Reaction Times ◽  
Visual Sensitivity ◽  
Gaze Direction ◽  
The Gaze ◽  
Visual Shift ◽  
Stimulus Speed ◽  
Posterior Parietal ◽  
Visual Reference

We asked to what extent the respective gaze direction influences (i) the spatial congruence of perceived direction of auditory and visual cues, and (ii) the discrimination of the direction of target motion. With fixed head position, subjects directed their gaze in various positions and localised auditory targets (band-pass noise, 2 kHz) presented at one of nine positions (straight ahead, or four symmetric positions to the left or right separated by 2.75 deg, respectively). Forced-choice judgements, whether the sound was perceived to the left or right of a visual reference light, show that the azimuth of the sound was perceived as slightly shifted to the left of a visual reference when the gaze was directed to the left, and vice versa. The maximum of this relative auditory - visual shift was 4.7 deg over a range of 45 deg (left or right) of gaze directions. In (ii), a spot of light started at the centre of a monitor and moved at 2 or 12 deg s−1 leftward or rightward. Subjects reported the direction by pressing a key; their gaze was directed at 0, 8, or 16 deg to the left or right. Mean choice-reaction times increased with increasing gaze eccentricity, but differently depending on stimulus direction and speed: with left fixation they were shorter for leftward than rightward motion; with right fixation they were shorter for rightward motion. This effect was stronger for the slow than for the fast stimulus speed. Thus, facilitation occurs when stimuli move with moderate velocity toward the direction of gaze. While the auditory-visual shift in (i) may reflect an incomplete transformation of spatial (craniocentric and oculocentric) coordinates as suggested by recordings in the primate midbrain, the results in (ii) conform with reports of specialised units in the posterior parietal cortex (areas LIP, 7a, MST) that, in registering oculomotor position, modulate visual sensitivity.

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