scholarly journals Some assembly required: building the fly eye for motion detection and colour discrimination

2020 ◽  
Vol 42 (5) ◽  
pp. 58-63
Author(s):  
Rhian F. Walther ◽  
Franck Pichaud
Keyword(s):  
Motion Detection ◽  
Moving Objects ◽  
Compound Eye ◽  
Lattice Structure ◽  
Fruit Fly ◽  
Colour Discrimination ◽  
Outward Appearance ◽  
The Many ◽  
Fly Eye ◽  
The Brain

Among the many eyes that have evolved on Earth, the insect compound eye is the most abundant. Its crystal-like lattice structure is a feat of engineering that has evolved over millions of years, and is exquisitely adapted to detect moving objects and discriminate colours. This enables many behaviours, including foraging for food, finding a mate and avoiding predators. Our understanding of how the compound eye is built and works has been greatly expanded by studying the humble fruit fly, Drosophila melanogaster. The simple outward appearance of the fly eye belies a host of sophisticated features. Through the precise arrangement of photosensitive cells in the retina and their connections to the brain, the fly eye packs an astonishing amount of hardware into a very tiny volume. In this primer, we introduce the molecular pathways that underpin the building and inner workings of the fly eye.

Three-Dimensional Time-Lapse Digital Movie Analysis of the Developing Fruit Fly Eye in Organ Culture

1997 ◽  
Vol 3 (S2) ◽  
pp. 1129-1130
Author(s):  
John Archie Pollock ◽  
Bejon T. Maneckshana ◽  
Teresa E. Leonardo
Keyword(s):  
Organ Culture ◽  
Compound Eye ◽  
Eye Development ◽  
Larval Instar ◽  
Three Dimensional ◽  
Fruit Fly ◽  
Time Lapse ◽  
Cell Types ◽  
Specific Cell ◽  
The Brain

The compound eye of the fruit fly, Drosophila melanogaster, is composed of a highly ordered array of facets (FIG. 1), each containing a precise set of neurons and supporting cells. The eye arises during the third larval instar from an undifferentiated epithelium, the eye imaginai disc, which is connected to the brain via the optic stalk (FIG. 2). During eye development, movement of the morphogenetic furrow, progressive recruitment of specific cell types and the growth of photoreceptor axons into the brain are each dynamic processes that are routinely studied indirectly in fixed tissues. While stereotyped development and the ‘crystalline’ like structure of the eye facilitates this analysis, certain experiments are hindered by the inability to observe developmental processes as they occur. To overcome this limitation, we have combined organ culture with advanced microscopy tools to enable the observation of eye development in living tissue.

scholarly journals Homothorax Controls a Binary Rhodopsin Switch in Drosophila Ocelli

2021 ◽  
Author(s):  
Abhishek Kumar Mishra ◽  
Cornelia Fritsch ◽  
Roumen Voutev ◽  
Richard S. Mann ◽  
Simon G. Sprecher
Keyword(s):  
Motion Detection ◽  
Compound Eye ◽  
Polarized Light ◽  
Fruit Fly ◽  
Compound Eyes ◽  
Light Perception ◽  
Ancestral Gene ◽  
Evolutionary Diversification ◽  
Opsin Genes ◽  
A Cell

Visual perception of the environment is mediated by specialized photoreceptor (PR) neurons of the eye. Each PR expresses photosensitive opsins, which are activated by a particular wavelength of light. In most insects, the visual system comprises a pair of compound eyes that are mainly associated with motion detection, color or polarized light perception and a triplet of ocelli that are thought to be critical during flight to detect horizon and movements. It is widely believed that evolutionary diversification of compound eye and ocelli in insects occurred from an ancestral visual organ around 500 million years ago. Concurrently, opsin genes were also duplicated to provide distinct spectral sensitivities to different PRs of compound eye and ocelli. In the fruit fly Drosophila melanogaster, Rhodopsin1 (Rh1) and Rh2 are closely related opsins that are originated from the duplication of a single ancestral gene. However, in the visual organs, Rh2 is uniquely expressed in ocelli whereas Rh1 is uniquely expressed in outer PRs of the compound eye. It is currently unknown how this differential expression of Rh1 and Rh2 in the two visual organs is controlled to provide unique spectral sensitivities to ocelli and compound eyes. Here, we show that Homothorax (Hth) is expressed in ocelli and confers proper rhodopsin expression. We find that Hth controls a binary rhodopsin switch in ocelli to promote Rh2 expression and repress Rh1 expression. Genetic and molecular analysis of rh1 and rh2 supports that Hth acts through their promoters to regulate rhodopsin expression in the ocelli. Finally, we also show that when ectopically expressed in the retina, hth is sufficient to induce Rh2 expression only at the outer PRs in a cell autonomous manner. We therefore propose that the diversification of rhodpsins in the ocelli and retinal outer PRs occurred by duplication of an ancestral gene, which is under the control of Homothorax.

Using Motion Detection to Measure Social Polarization in the U.S. House of Representatives

2020 ◽  
pp. 1-10
Author(s):  
Bryce J. Dietrich
Keyword(s):  
Motion Detection ◽  
House Of Representatives ◽  
Social Science Research ◽  
Image Data ◽  
Science Research ◽  
Video Data ◽  
Social Scientists ◽  
Wide Range ◽  
Party Voting ◽  
The Many

Abstract Although previous scholars have used image data to answer important political science questions, less attention has been paid to video-based measures. In this study, I use motion detection to understand the extent to which members of Congress (MCs) literally cross the aisle, but motion detection can be used to study a wide range of political phenomena, like protests, political speeches, campaign events, or oral arguments. I find not only are Democrats and Republicans less willing to literally cross the aisle, but this behavior is also predictive of future party voting, even when previous party voting is included as a control. However, this is one of the many ways motion detection can be used by social scientists. In this way, the present study is not the end, but the beginning of an important new line of research in which video data is more actively used in social science research.

scholarly journals Is There a Brain Microbiome?

2021 ◽  
Vol 16 ◽  
pp. 263310552110187
Author(s):  
Christopher D Link
Keyword(s):  
Animal Models ◽  
Human Brain ◽  
Neurodegenerative Diseases ◽  
Ground Truth ◽  
Healthy Human ◽  
Strong Motivation ◽  
The Many ◽  
The Brain

Numerous studies have identified microbial sequences or epitopes in pathological and non-pathological human brain samples. It has not been resolved if these observations are artifactual, or truly represent population of the brain by microbes. Given the tempting speculation that resident microbes could play a role in the many neuropsychiatric and neurodegenerative diseases that currently lack clear etiologies, there is a strong motivation to determine the “ground truth” of microbial existence in living brains. Here I argue that the evidence for the presence of microbes in diseased brains is quite strong, but a compelling demonstration of resident microbes in the healthy human brain remains to be done. Dedicated animal models studies may be required to determine if there is indeed a “brain microbiome.”

A discussion of apraxia, aphasia, and gestural language

1984 ◽  
Vol 246 (6) ◽  
pp. R884-R887
Author(s):  
N. Helm-Estabrooks
Keyword(s):  
Sign Language ◽  
Cerebral Hemisphere ◽  
Communication Disorder ◽  
Left Cerebral Hemisphere ◽  
Language Behavior ◽  
Normal Language ◽  
Symbolic Gestures ◽  
The Many ◽  
The Relationship ◽  
The Brain

It is understood that damage to the left cerebral hemisphere in adulthood may result in syndromes of language disturbances called the aphasias. The study of these syndromes sheds light on normal language processes, the relationship between language behavior and the brain, and how best to treat aphasic individuals. Aphasia, for some, is a central communication disorder affecting all symbolic behavior in all modalities (i.e., speech, writing, and gesture). Difficulty producing symbolic gestures on command is called apraxia. Others view aphasia as a manifestation of a motor-sequencing disorder affecting all gestural systems including those required for speech movements. These divergent theories of the underlying nature of aphasia can be tested through examination of deaf individuals who use sign language before onset of aphasia. Poizner et al. [Am. J. Physiol. 246 (Regulatory Integrative Comp. Physiol. 15): R868-R883, 1984] studied three such patients with different aphasia syndromes: one patient had a nonsymbolic, motor-sequencing disorder; one had a gestural apraxia; and one had neither. These findings force the conclusion that neither the symbolic nor motor-sequencing theory of aphasia can account for the many varieties of that disorder.

scholarly journals Features of diagnosis of cognitive disorders in patients with chronic brain ischemia

2016 ◽  
pp. 8-11
Author(s):  
N.P. Pavliuk
Keyword(s):  
Quality Of Life ◽  
Health Care ◽  
Cognitive Impairment ◽  
Cognitive Disorders ◽  
Chronic Ischemia ◽  
Modern Health Care ◽  
Chronic Brain Ischemia ◽  
The Many ◽  
The Brain

One of the major problems in modern health care are cerebrovascular disease, which occupy a leading place in the structure of mortality and disability in the population. Among the many clinical features of chronic ischemia of the brain is a key manifestation of cognitive impairment that often determine the severity of condition and quality of life of the patient and his relatives. Diagnosis of cognitive impairment is very important, as the timely appointment of therapy may prevent or at least delay the development of dementia.

scholarly journals CORTICAL PHASE TRANSITIONS, NONEQUILIBRIUM THERMODYNAMICS AND THE TIME-DEPENDENT GINZBURG–LANDAU EQUATION

2012 ◽  
Vol 26 (06) ◽  
pp. 1250035 ◽  
Author(s):  
WALTER J. FREEMAN ◽  
ROBERTO LIVI ◽  
MASASHI OBINATA ◽  
GIUSEPPE VITIELLO
Keyword(s):  
Phase Transitions ◽  
Landau Equation ◽  
Power Laws ◽  
Time Dependent ◽  
Many Body ◽  
Ginzburg Landau ◽  
Ginzburg Landau Equation ◽  
Characteristic Space ◽  
The Many ◽  
The Brain

The formation of amplitude modulated and phase modulated assemblies of neurons is observed in the brain functional activity. The study of the formation of such structures requires that the analysis has to be organized in hierarchical levels, microscopic, mesoscopic, macroscopic, each with its characteristic space-time scales and the various forms of energy, electric, chemical, thermal produced and used by the brain. In this paper, we discuss the microscopic dynamics underlying the mesoscopic and the macroscopic levels and focus our attention on the thermodynamics of the nonequilibrium phase transitions. We obtain the time-dependent Ginzburg–Landau equation for the nonstationary regime and consider the formation of topologically nontrivial structures such as the vortex solution. The power laws observed in functional activities of the brain is also discussed and related to coherent states characterizing the many-body dissipative model of brain.

scholarly journals Neuronal Correlates of Multiple Top–Down Signals during Covert Tracking of Moving Objects in Macaque Prefrontal Cortex

2012 ◽  
Vol 24 (10) ◽  
pp. 2043-2056 ◽  
Author(s):  
Ayano Matsushima ◽  
Masaki Tanaka
Keyword(s):  
Prefrontal Cortex ◽  
Object Tracking ◽  
Visual Processing ◽  
Moving Objects ◽  
Top Down ◽  
Selective Suppression ◽  
Internal Object ◽  
Object Segregation ◽  
Task Irrelevant ◽  
The Brain

Resistance to distraction is a key component of executive functions and is strongly linked to the prefrontal cortex. Recent evidence suggests that neural mechanisms exist for selective suppression of task-irrelevant information. However, neuronal signals related to selective suppression have not yet been identified, whereas nonselective surround suppression, which results from attentional enhancement for relevant stimuli, has been well documented. This study examined single neuron activities in the lateral PFC when monkeys covertly tracked one of randomly moving objects. Although many neurons responded to the target, we also found a group of neurons that exhibited a selective response to the distractor that was visually identical to the target. Because most neurons were insensitive to an additional distractor that explicitly differed in color from the target, the brain seemed to monitor the distractor only when necessary to maintain internal object segregation. Our results suggest that the lateral PFC might provide at least two top–down signals during covert object tracking: one for enhancement of visual processing for the target and the other for selective suppression of visual processing for the distractor. These signals might work together to discriminate objects, thereby regulating both the sensitivity and specificity of target choice during covert object tracking.

Information-based Analysis of the Coupling between Dynamic Visual Stimuli, Eye Movements, and Brain Signals

2021 ◽  
pp. 2150048
Author(s):  
Hamidreza Namazi ◽  
Avinash Menon ◽  
Ondrej Krejcar
Keyword(s):  
Eye Movements ◽  
Moving Objects ◽  
Brain Activity ◽  
Visual Stimuli ◽  
Strongly Correlated ◽  
Eeg Signals ◽  
Vision Science ◽  
Brain Signals ◽  
Information Contents ◽  
The Brain

Our eyes are always in search of exploring our surrounding environment. The brain controls our eyes’ activities through the nervous system. Hence, analyzing the correlation between the activities of the eyes and brain is an important area of research in vision science. This paper evaluates the coupling between the reactions of the eyes and the brain in response to different moving visual stimuli. Since both eye movements and EEG signals (as the indicator of brain activity) contain information, we employed Shannon entropy to decode the coupling between them. Ten subjects looked at four moving objects (dynamic visual stimuli) with different information contents while we recorded their EEG signals and eye movements. The results demonstrated that the changes in the information contents of eye movements and EEG signals are strongly correlated ([Formula: see text]), which indicates a strong correlation between brain and eye activities. This analysis could be extended to evaluate the correlation between the activities of other organs versus the brain.

Writing About Dance

2010 ◽  
Author(s):  
Wendy R. Oliver
Keyword(s):  
Critical Thinking ◽  
Thinking Skills ◽  
Critical Thinking Skills ◽  
Research Papers ◽  
Art Form ◽  
Writing Assignment ◽  
The Many ◽  
The Brain

Master the art of writing about dance! And learn about dance at the same time. This comprehensive guide provides students with instructions for writing about dance in many different contexts. It brings together the many different kinds of writing that can be effectively used in a variety of dance classes from technique to appreciation. In addition, it offers strategies for improving critical thinking skills, and shows how writing and critical thinking are closely linked. Part I focuses on informal writing such as freewriting, with sample exercises and prompts. Part II outlines approaches to writing three different kinds of formal papers: critiques, essays and research papers. Writing about dance teaches on two levels. First, the writer is learning dance content as s/he writes. Engaging in the writing assignment causes the writer to take a look at an aspect of dance and to become a 'momentary expert'. Secondly, writing itself is a way of learning. Writing involves the brain in three kinds of interaction, that is, the intellectual act of critically thinking, the physical act of writing or typing, and the visual aspect of seeing the writing on the page. The critical thinking and contemplation involved in writing can deepen students understanding of dance technique, dance creativity, and dance as an art form. Students will use this book on their own, or teachers may make assignments from it. It teaches about dance writing, but also about the very basics of dance appreciation.

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