Multi-Level Processes and Retina–Brain Pathways of Photic Regulation of Mood

Light exerts powerful biological effects on mood regulation. Whereas the source of photic information affecting mood is well established at least via intrinsically photosensitive retinal ganglion cells (ipRGCs) secreting the melanopsin photopigment, the precise circuits that mediate the impact of light on depressive behaviors are not well understood. This review proposes two distinct retina–brain pathways of light effects on mood: (i) a suprachiasmatic nucleus (SCN)-dependent pathway with light effect on mood via the synchronization of biological rhythms, and (ii) a SCN-independent pathway with light effects on mood through modulation of the homeostatic process of sleep, alertness and emotion regulation: (1) light directly inhibits brain areas promoting sleep such as the ventrolateral preoptic nucleus (VLPO), and activates numerous brain areas involved in alertness such as, monoaminergic areas, thalamic regions and hypothalamic regions including orexin areas; (2) moreover, light seems to modulate mood through orexin-, serotonin- and dopamine-dependent pathways; (3) in addition, light activates brain emotional processing areas including the amygdala, the nucleus accumbens, the perihabenular nucleus, the left hippocampus and pathways such as the retina–ventral lateral geniculate nucleus and intergeniculate leaflet–lateral habenula pathway. This work synthetizes new insights into the neural basis required for light influence mood

Photoinduced isomerization sampling of retinal in bacteriorhodopsin

Photoisomerization of retinoids inside a confined protein pocket represents a critical chemical event in many important biological processes from animal vision, non-visual light effects, to bacterial light sensing and harvesting. Light driven proton pumping in bacteriorhodopsin entails exquisite electronic and conformational reconfigurations during its photocycle. However, it has been a major challenge to delineate transient molecular events preceding and following the photoisomerization of the retinal from noisy electron density maps when varying populations of intermediates coexist and evolve as a function of time. Here I report several distinct early photoproducts deconvoluted from the recently observed mixtures in time-resolved serial crystallography. This deconvolution substantially improves the quality of the electron density maps hence demonstrates that the all-trans retinal undergoes extensive isomerization sampling before it proceeds to the productive 13-cis configuration. Upon light absorption, the chromophore attempts to perform trans-to-cis isomerization at every double bond coupled with the stalled anti-to-syn rotations at multiple single bonds along its polyene chain. Such isomerization sampling pushes all seven transmembrane helices to bend outward, resulting in a transient expansion of the retinal binding pocket, and later, a contraction due to recoiling. These ultrafast responses observed at the atomic resolution support that the productive photoreaction in bacteriorhodopsin is initiated by light-induced charge separation in the prosthetic chromophore yet governed by stereoselectivity of its protein pocket. The method of a numerical resolution of concurrent events from mixed observations is also generally applicable.

Photoinduced isomerization sampling of retinal in bacteriorhodopsin

Photoisomerization of retinoids inside a confined protein pocket represents a critical chemical event in many important biological processes from animal vision, non-visual light effects, to bacterial light sensing and harvesting. Light driven proton pumping in bacteriorhodopsin entails exquisite electronic and conformational reconfigurations during its photocycle. However, it has been a major challenge to delineate transient molecular events preceding and following the photoisomerization of the retinal from noisy electron density maps when varying populations of intermediates coexist and evolve as a function of time. Here I report several distinct early photoproducts deconvoluted from the recently observed mixtures in time-resolved serial crystallography. This deconvolution substantially improves the quality of the electron density maps hence demonstrates that the all-trans retinal undergoes extensive isomerization sampling before it proceeds to the productive 13-cis configuration. Upon light absorption, the chromophore attempts to perform trans-to-cis isomerization at every double bond coupled with the stalled anti-to-syn rotations at multiple single bonds along its polyene chain. Such isomerization sampling pushes all seven transmembrane helices to bend outward, resulting in a transient expansion of the retinal binding pocket, and later, a contraction due to recoiling. These ultrafast responses observed at the atomic resolution support that the productive photoreaction in bacteriorhodopsin is initiated by light-induced charge separation in the prosthetic chromophore yet governed by stereoselectivity of its protein pocket. The method of a numerical resolution of concurrent events from mixed observations is also generally applicable.

In search of blue-light effects on cognitive control

People are constantly exposed to blue light while engaging in work. It is thus crucial to understand if vast exposure to blue light influences cognitive control, which is essential for working efficiently. Previous studies proposed that the stimulation of intrinsically photosensitive retinal ganglion cells (ipRGCs), a newly discovered photoreceptor that is highly sensitive to blue light, could modulate non-image forming functions. Despite studies that showed blue light (or ipRGCs) enhances brain activations in regions related to cognitive control, how exposure to blue light changes our cognitive control behaviorally remains elusive. We examined whether blue light influences cognitive control through three behavioral tasks in three studies: the sustained attention to response task (SART), the task-switching paradigm, and the Stroop task. Classic effects of the SART, switch cost, and the Stroop effect were found, but no differences were observed in results of different background lights across the six experiments. Together, we conclude that these domains of cognitive control are not influenced by blue light and ipRGCs, and whether the enhancement of blue light on brain activities extends to the behavioral level should be carefully re-examined.

Correlated color temperature and light intensity: Complementary features in non-visual light field

An appropriate exposure to the light-dark cycle, with high irradiances during the day and darkness during the night is essential to keep our physiology on time. However, considering the increasing exposure to artificial light at night and its potential harmful effects on health (i.e. chronodisruption and associated health conditions), it is essential to understand the non-visual effects of light in humans. Melatonin suppression is considered the gold standard for nocturnal light effects, and the activation of intrinsically photosensitive retinal ganglion cells (ipRGCs) through the assessment of pupillary light reflex (PLR) has been recently gaining attention. Also, some theoretical models for melatonin suppression and retinal photoreceptors activation have been proposed. Our aim in this study was to determine the influence of correlated color temperature (CCT) on melatonin suppression and PLR, considering two commercial light sources, as well as to explore the possible correlation between both processes. Also, the contribution of irradiance (associated to CCT) was explored through mathematical modelling on a wider range of light sources. For that, melatonin suppression and PLR were experimentally assessed on 16 healthy and young volunteers under two light conditions (warmer, CCT 3000 K; and cooler, CCT 5700 K, at ~5·1018 photons/cm2/sec). Our experimental results yielded greater post-stimulus constriction under the cooler (5700 K, 13.3 ± 1.9%) than under the warmer light (3000 K, 8.7 ± 1.2%) (p < 0.01), although no significant differences were found between both conditions in terms of melatonin suppression. Interestingly, we failed to demonstrate correlation between PLR and melatonin suppression. Although methodological limitations cannot be discarded, this could be due to the existence of different subpopulations of Type 1 ipRGCs differentially contributing to PLR and melatonin suppression, which opens the way for further research on ipRGCs projection in humans. The application of theoretical modelling suggested that CCT should not be considered separately from irradiance when designing nocturnal/diurnal illumination systems. Further experimental studies on wider ranges of CCTs and light intensities are needed to confirm these conclusions.

Interpretation Strategies of Contemporary Musical and Theatrical Art: Trends, Factors

Relevance of the study. The modern interpretive content main tendencies of the European and Ukrainian musical and theatrical art were analyzed. Forms of interpretation being were considered in the coordinates of the “composer-listener-performer” triad in the aspect of its correspondence to its time artistic intentions. The scientific novelty of the study is in the analysis of innovative projects most of which are not adapted to musicology and in the formulation of trends and factors of modern musical art’s interpretive policy. Main objective of the study is to determine the specifics and factors of the modern interpretations of a musical and theatrical art. Methodology. The following methods have been adapted: the interpretive — in relation to the analyzed opera projects; the hermeneutic-semantic — for the purpose of identify the interpreted works’ intonation-image specificity; the comparative — to juxtaposition the “interpretive behavior” of one work in different performance versions; the intonation-dramaturgical analysis — to study the specifics and factors of works’ interpretive versions. Results and conclusions. The modern interpretive reality initiates the emergence of radically new and the consolidation of existing non-standard trends in the work’s representation. These are: the instrumental performing theatricalization, significant expansion of the improvisation’s zone, abandonment of the opera genre canons with an emphasis on synthetic genres of performative nature and the use of bold audio, scenographic, color and light effects. The modern interpretative main trends are the actualization, the alienation and the emergence of working remote versions, the encroachment on the textual and intonational essence of a known work by adding the new material (the integral opus or the fragmentary inlay), the emergence of modern composer’s alternative role which is a co-author of a new hybrid product thanks to the connection to the work of the past. Findings of the research. The specifics and factors of work’s variant-interpretive realization are analytically argued. The main factors are the genre-intonation specificity, the synthetic and intertextual nature, the complexity and synergy of text semantic intentions, the recipient’s culturalhistorical awareness, the socio-cultural intentions’ balance of the author and his artistic will performers, the degree of text openness, the context. Prospects for further exploration in this direction. The following research areas are needed: 1) the development of new methods and terminological apparatus suitable for the modern artifacts’ analysis; 2) the analytical base’s expansion due to: a) the further accumulation of examples, b) the scientific adaptation of various genres’ works.

ARTISTIC EXPRESSION OF CARICATURES OF PEOPLE'S ARTIST HUSEYNGULU ALIYEV

In Huseyngulu Aliyev's works, we always see the successful expression of harsh color transitions, tonal spots, light effects, instant glare in the formation of dynamism, as well as the artist's unique creative position with different compositional structures in the more exciting presentation of these effects. In his work "Molla Nasreddin", which is currently preserved in a private collection in Norway, the artist expressed the deep expression of dynamism in the composition, both in the intensity of movements, sudden jumps, hymns of speed, and the contrasting transition of colors from light to dark or vice versa. It is interesting to recreate the artistic solution of the instantaneous plot in which the fruit of the old man, sitting on a fast-running donkey, spreads in the air and begins to scatter in the air. The clear language of caricatures created by Huseyngulu Aliyev, which combines both matte and bright tones of colors such as green, yellow and brown, is very thought-provoking due to their mobility and dynamism. Created in 1993, the interesting language of expression of the works, which is a vivid example of the idea mentioned in the cartoons with ink and pen, attracts attention. In "Unsuccesfull" the intention of a thief in a black mask to plunder the country, but before that the looting of these places ended in the failure of his plan. The astonishment of the robber looking at the empty baskets and glasses scattered on the ground makes it possible to imagine the facial features he covers. The clear language of caricatures created by Huseyngulu Aliyev is also very thought-provoking due to their mobility and dynamism. Created in 1993, the interesting language of expression of the works, which is a vivid example of the idea mentioned in the cartoons with ink and pen, attracts attention. In "Unsuccesfull" the intention of a thief in a black mask to plunder the country, but before that the looting of these places ended in the failure of his plan.The astonishment of the robber looking at the empty baskets and glasses scattered on the ground makes it possible to imagine the facial features he covers. Among the graphic examples created in the mentioned period, the unique composition of the work "Roads" attracts the attention of the audience with its interesting composition, which has a great meaning. The artist sang the song of a long way with the movement of crowded people in the same direction. The march of people who join the movement on an empty background expresses their common thinking and will. Here, the artist has successfully implemented mass thinking, not where and why the roads go. It is well-known that art, which came to art by chance, but managed to introduce itself in any way, has gained popularity in our time. The artist's very interesting and humorous composition in his caricature "Patriot of art" created about 20 years ago is dedicated to this type of "artists". The stage hymn of the performance of a long-eared man holding his tambourine in his hands in an artistic form clearly expresses the artist's purpose. The solution of the symbolic meaning given to some scenes of life by the artist using folk sayings in the unique compositional structure gives the basis to evaluate the artist's creativity by presenting it in a different form in each work. For example, in his 2001 work, “They Make the Old Moon a Star”, he praised an astrologer sitting on his back with his head cut off and turning the old moon into a star in the sky. The artist was referring to people who were ungrateful and apostate (Figure 2.91). In Huseyngulu Aliyev's caricatures, artistic exaggerations, different assessments of events or directing them in accordance with the content of the work are of interest as creative extraordinary creative discoveries. For example, the artist, who turned a fragment from the world-famous sculptor Auguste Rodin's "The Thinker" into the content of the painting, watched the two snakes collide, fight, and try to poison each other, thinking deeply about world events. Here, the sharpness of the artistic generalization in such a difficult scene as the destruction of the same sex makes the viewer think (Figure 2.96).

Dissecting and modeling photic and melanopsin effects to predict sleep disturbances induced by irregular light exposure in mice

Artificial lighting, day-length changes, shift work, and transmeridian travel all lead to sleep–wake disturbances. The nychthemeral sleep–wake cycle (SWc) is known to be controlled by output from the central circadian clock in the suprachiasmatic nuclei (SCN), which is entrained to the light–dark cycle. Additionally, via intrinsically photosensitive retinal ganglion cells containing the photopigment melanopsin (Opn4), short-term light–dark alternations exert direct and acute influences on sleep and waking. However, the extent to which longer exposures typically experienced across the 24-h day exert such an effect has never been clarified or quantified, as disentangling sustained direct light effects (SDLE) from circadian effects is difficult. Recording sleep in mice lacking a circadian pacemaker, either through transgenesis (Syt10cre/creBmal1fl/-) or SCN lesioning and/or melanopsin-based phototransduction (Opn4−/−), we uncovered, contrary to prevailing assumptions, that the contribution of SDLE is as important as circadian-driven input in determining SWc amplitude. Specifically, SDLE were primarily mediated (>80%) through melanopsin, of which half were then relayed through the SCN, revealing an ancillary purpose for this structure, independent of its clock function in organizing SWc. Based on these findings, we designed a model to estimate the effect of atypical light–dark cycles on SWc. This model predicted SWc amplitude in mice exposed to simulated transequatorial or transmeridian paradigms. Taken together, we demonstrate this SDLE is a crucial mechanism influencing behavior on par with the circadian system. In a broader context, these findings mandate considering SDLE, in addition to circadian drive, for coping with health consequences of atypical light exposure in our society.

Optomechanically Induced Transparency and Slow–Fast Light Effect in Hybrid Cavity Optomechanical Systems

We theoretically investigate the optomechanically induced transparency (OMIT) phenomenon and the fast and slow light effects of a four-mode optomechanical system with the Kerr medium. The optomechanical system is composed of an array of three single-mode cavities and a mechanical oscillator. The three cavities are a passive cavity, a no-loss-gain cavity and a gain optical cavity, respectively. A Kerr medium is inserted in the passive cavity. We study the influence of the Kerr medium on the stability of the optomechanical system, and find that the stable regime of the optomechanical system can be adjusted by changing the Kerr coefficient. We demonstrate that the phenomenon of optomechanically induced transparency will appear when the Kerr medium exists in the optomechanical system and find that the frequency position of the absorption peak on the left increases linearly with the Kerr coefficient. In addition, we also investigate the fast and slow light effects in this system. The results show that we can control the fast and slow light by adjusting the Kerr coefficient, tunneling strength, and driving field strength. This study has potential application prospects in the fields of quantum optical devices and quantum information processing.