scholarly journals Optimal flickering light stimulation for entraining gamma waves in the human brain

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kanghee Lee ◽  
Yeseung Park ◽  
Seung Wan Suh ◽  
Sang-Su Kim ◽  
Do-Won Kim ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Adverse Effects ◽  
White Light ◽  
Light Stimulus ◽  
Red Light ◽  
Brain Regions ◽  
Amyloid Burden ◽  
Color Intensity ◽  
Light Stimulation ◽  
Flickering Light

AbstractAlthough light flickering at 40 Hz reduced Alzheimer’s disease (AD) pathologies in mice by entraining gamma waves, it failed to reduce cerebral amyloid burden in a study on six patients with AD or mild cognitive impairment. We investigated the optimal color, intensity, and frequency of the flickering light stimulus for entraining gamma waves in young adults. We compared the event-related synchronization (ERS) values of entrained gamma waves between four different light colors (white, red, green, and blue) in the first experiment and four different luminance intensities in the second experiment. In both experiments, we compared the ERS values of entrained gamma waves between 10 different flickering frequencies from 32 to 50 Hz. We also examined the severity of six adverse effects in both experiments. We compared the propagation of gamma waves in the visual cortex to other brain regions between different luminance intensities and flickering frequencies. We found that red light entrained gamma waves most effectively, followed by white light. Lights of higher luminance intensities (700 and 400 cd/m2) entrained stronger gamma waves than those of lower luminance intensities (100 and 10 cd/m2). Lights flickering at 34–38 Hz entrained stronger and more widely spread beyond the visual cortex than those flickering at 40–50 Hz. Light of 700 cd/m2 resulted in more moderate-to-severe adverse effects than those of other luminance intensities. In humans, 400 cd/m2 white light flickering at 34–38 Hz was most optimal for gamma entrainment.

scholarly journals Cataract type and pupillary response to blue and white light stimuli

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Manami Kuze ◽  
Kazuno Negishi ◽  
Toshiyuki Koyasu ◽  
Mineo Kondo ◽  
Kazuo Tsubota ◽  
...  
Keyword(s):  
Blue Light ◽  
Stimulus Duration ◽  
White Light ◽  
Light Stimulus ◽  
Pupillary Response ◽  
Ocular Lens ◽  
Light Stimulation ◽  
Significant Difference ◽  
Light Stimuli ◽  
Pupil Reaction

AbstractWe evaluated the pupil reaction to blue and white light stimulation in 70 eyes with cataract and in 38 eyes with a selective blue-light filtering intra-ocular lens. The diameter of the pupil before stimulation was set as baseline (BPD) and, after a stimulus duration of 1 s, the post-illumination pupillary response (PIPR) was measured using an electronic pupillometer. The BPD showed no significant difference among three grades of nuclear sclerosis (NS). In contrast, the PIPRs differed significantly among the NS grades eyes including with and without subcapsular cataract (SC) and IOL eyes for white light (p < 0.05, Kruskal–Wallis test), but not for blue light. Subcapsular opacity did not affect the BPD or PIPR in all cataract grades for either light stimulus. The tendency of larger PIPR in the pseudophakic eyes than the cataract eyes for both lights, however significant difference was found only for white light (p < 0.05 for white light, p > 0.05 for blue light). Our study demonstrates retention of the PIPR for blue light, but not for white light in cataract eyes. We also confirmed that the pupillary response in pseudohakic eyes with a selective blue light-filtering intra ocular lens was greater than that in cataractous eyes for white light.

scholarly journals Neural activation in photosensitive brain regions of Atlantic salmon (Salmo salar) after light stimulation

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0258007
Author(s):  
Mariann Eilertsen ◽  
Benjamin G. J. Clokie ◽  
Lars O. E. Ebbesson ◽  
Cristina Tanase ◽  
Herve Migaud ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Neural Activity ◽  
Expression Patterns ◽  
Red Light ◽  
Brain Regions ◽  
Neural Activation ◽  
Apparent Difference ◽  
Light Stimulation ◽  
Deep Brain Photoreceptors ◽  
Deep Brain

Photoreceptive inputs to the teleost brain are perceived as image of the visual world and as photo-modulation of neuroendocrine and neuronal signals. The retina and pineal organ are major receptive organs with projections to various parts of the brain, but in the past decades deep brain photoreceptors have emerged as candidates for photoreceptive inputs, either independent or in combination with projections from light sensory organs. This study aimed to test the effects of narrow bandwidth light using light-emitting diodes technology on brain neural activity through putative opsin stimulation in Atlantic salmon. The expression of c-fos, a known marker of neural activity, was compared in situ between dark-adapted salmon parr and following light stimulation with different wavelengths. c-fos expression increased with duration of light stimulation and the strongest signal was obtained in fish exposed to light for 120 minutes. Distinct and specific brain regions were activated following dark to light stimulation, such as the habenula, suprachiasmatic nucleus, thalamus, and hypothalamus. The c-fos expression was overlapping with photoreceptors expressing melanopsin and/or vertebrate ancient opsin, suggesting a potential direct activation by light. Interestingly in the habenula, a distinct ring of vertebrate ancient opsin and melanopsin expressing cells is overlapping with c-fos expression after neural activation. Salmon exposed to different spectra had neural activation in similar brain regions. The most apparent difference was melanopsin expression in the lateral cells of the lateral tuberal nuclus in the hypothalamus, which appeared to be specifically activated by red light. Light-stimulated neuronal activity in the deep brain was limited to subpopulations of neurons, mainly in regions with neuronal modulation activity, retinal and pineal innervations and known presence of nonvisual photoreceptors. The overlapping expression patterns of c-fos and nonvisual opsins support direct light stimulation of deep brain photoreceptors and the importance of these systems in light induced brain activity.

Behavioural responses of the haematophagous bug Triatoma infestans (Klug) (Hemiptera: Reduviidae) to visual stimuli

1982 ◽  
Vol 72 (3) ◽  
pp. 357-366 ◽  
Author(s):  
J. P. Ward ◽  
L. H. Finlayson
Keyword(s):  
White Light ◽  
Infrared Radiation ◽  
Near Infrared ◽  
Moving Objects ◽  
Light Stimulus ◽  
Red Light ◽  
Visual Stimuli ◽  
Triatoma Infestans ◽  
Lower Intensity ◽  
Behavioural Responses

AbstractBehavioural responses of Triatoma infestans (Klug) to visual stimuli were analysed using a novel method involving remote monitoring of individual tethered bugs. T. infestans showed negative phototactic behaviour and a reduction in activity in response to a directional white light stimulus at an intensity of 1·2 /µW/cm2. A lower intensity of white light (0·6 µW/cm2) elicited a similar negative phototaxis but failed to induce a significant reduction in activity. The response to green light at 0·6 µW/cm2 was similar to that towards white light at 1·2 µW/cm2. Blue light did not induce any behavioural responses, whereas red light induced a significant reduction in activity at the lower intensity but did not affect phototaxis. Infrared radiation did not induce any significant behavioural effects, but there was an indication that T. infestans can detect near infrared radiation (750 nm). The activity response to the higher intensity white light appeared to be mediated primarily by the compound eyes. The dorsal ocelli, however, were involved in the directing of the phototactic response. T. infestans responded to moving objects by a marked reduction in activity. Slowly moving objects induced a following response, whereas more quickly moving objects did not.

scholarly journals Mechanisms Underlying the Cognitive and Behavioural Effects of Maternal Obesity

Nutrients ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 240
Author(s):  
Kyoko Hasebe ◽  
Michael D. Kendig ◽  
Margaret J. Morris
Keyword(s):  
Animal Models ◽  
Adverse Effects ◽  
Gut Microbiome ◽  
Maternal Obesity ◽  
Maternal Diet ◽  
Affective State ◽  
Brain Regions ◽  
Brain Network ◽  
Physical And Mental Health ◽  
Obesogenic Diet

The widespread consumption of ‘western’-style diets along with sedentary lifestyles has led to a global epidemic of obesity. Epidemiological, clinical and preclinical evidence suggests that maternal obesity, overnutrition and unhealthy dietary patterns programs have lasting adverse effects on the physical and mental health of offspring. We review currently available preclinical and clinical evidence and summarise possible underlying neurobiological mechanisms by which maternal overnutrition may perturb offspring cognitive function, affective state and psychosocial behaviour, with a focus on (1) neuroinflammation; (2) disrupted neuronal circuities and connectivity; and (3) dysregulated brain hormones. We briefly summarise research implicating the gut microbiota in maternal obesity-induced changes to offspring behaviour. In animal models, maternal obesogenic diet consumption disrupts CNS homeostasis in offspring, which is critical for healthy neurodevelopment, by altering hypothalamic and hippocampal development and recruitment of glial cells, which subsequently dysregulates dopaminergic and serotonergic systems. The adverse effects of maternal obesogenic diets are also conferred through changes to hormones including leptin, insulin and oxytocin which interact with these brain regions and neuronal circuits. Furthermore, accumulating evidence suggests that the gut microbiome may directly and indirectly contribute to these maternal diet effects in both human and animal studies. As the specific pathways shaping abnormal behaviour in offspring in the context of maternal obesogenic diet exposure remain unknown, further investigations are needed to address this knowledge gap. Use of animal models permits investigation of changes in neuroinflammation, neurotransmitter activity and hormones across global brain network and sex differences, which could be directly and indirectly modulated by the gut microbiome.

scholarly journals Intranasal Allopregnanolone Confers Rapid Seizure Protection: Evidence for Direct Nose-to-Brain Delivery

2021 ◽  
Author(s):  
Dorota Zolkowska ◽  
Chun-Yi Wu ◽  
Michael A. Rogawski
Keyword(s):  
Adverse Effects ◽  
Screen Test ◽  
Brain Regions ◽  
Seizure Threshold ◽  
Brain Delivery ◽  
Intranasal Delivery ◽  
Behavioral Impairment ◽  
Loss Of Righting Reflex ◽  
Ptz Test ◽  
Central Nervous System Activity

AbstractAllopregnanolone, a positive modulator of GABAA receptors with antiseizure activity, has potential in the treatment of seizure emergencies. Instillation of allopregnanolone in 40% sulfobutylether-β-cyclodextrin into the nose in mice rapidly elevated the seizure threshold in the timed intravenous pentylenetetrazol (ED50, 5.6 mg/kg), picrotoxin (ED50, 5.9 mg/kg), and bicuculline seizure tests. The effect peaked at 15 min, decayed over 1 h, and was still evident in some experiments at 6 h. Intranasal allopregnanolone also delayed the onset of seizures in the maximal PTZ test. At an allopregnanolone dose (16 mg/kg) that conferred comparable effects on seizure threshold as the benzodiazepines midazolam and diazepam (both at doses of 1 mg/kg), allopregnanolone caused minimal sedation or motor toxicity in the horizontal screen test whereas both benzodiazepines produced marked behavioral impairment. In addition, intranasal allopregnanolone failed to cause loss-of-righting reflex in most animals, but when the same dose was administered intramuscularly, all animals became impaired. Intranasal allopregnanolone (10 mg/kg) caused a rapid increase in brain allopregnanolone with a Tmax of ~5 min after initiation of the intranasal delivery. High levels of allopregnanolone were recovered in the olfactory bulb (Cmax, 16,000 ng/mg) whereas much lower levels (Cmax, 670 ng/mg) were present in the remainder of the brain. We conclude that the unique ability of intranasal allopregnanolone to protect against seizures without inducing behavioral adverse effects is due in part to direct nose-to-brain delivery, with preferential transport to brain regions relevant to seizures. Benzodiazepines are commonly administered intranasally for acute seizure therapy, including for the treatment of acute repetitive seizures, but are not transported from nose-to-brain. Intranasal allopregnanolone acts with greater speed, has less propensity for adverse effects, and has the ability to overcome benzodiazepine refractoriness. This is the first study demonstrating rapid functional central nervous system activity of a nose-to-brain-delivered steroid. Intranasal delivery circumvents the poor oral bioavailability of allopregnanolone providing a route of administration permitting its evaluation as a treatment for diverse neuropsychiatric indications.

scholarly journals The Preferences of Different Cultivars of Lettuce Seedlings (Lactuca sativa L.) for the Spectral Composition of Light

Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1211
Author(s):  
Barbara Frąszczak ◽  
Monika Kula-Maximenko
Keyword(s):  
Chlorophyll Content ◽  
Blue Light ◽  
White Light ◽  
Leaf Shape ◽  
Red Light ◽  
Spectral Composition ◽  
Fresh Weight ◽  
Light Spectrum ◽  
Dark Green ◽  
Relative Chlorophyll Content

The spectrum of light significantly influences the growth of plants cultivated in closed systems. Five lettuce cultivars with different leaf colours were grown under white light (W, 170 μmol m−2 s−1) and under white light with the addition of red (W + R) or blue light (W + B) (230 μmol m−2 s−1). The plants were grown until they reached the seedling phase (30 days). Each cultivar reacted differently to the light spectrum applied. The red-leaved cultivar exhibited the strongest plasticity in response to the spectrum. The blue light stimulated the growth of the leaf surface in all the plants. The red light negatively influenced the length of leaves in the cultivars, but it positively affected their number in red and dark-green lettuce. It also increased the relative chlorophyll content and fresh weight gain in the cultivars containing anthocyanins. When the cultivars were grown under white light, they had longer leaves and higher value of the leaf shape index. The light-green cultivars had a greater fresh weight. Both the addition of blue and red light significantly increased the relative chlorophyll content in the dark-green cultivar. The spectrum enhanced with blue light had positive influence on most of the parameters under analysis in butter lettuce cultivars. These cultivars were also characterised by the highest absorbance of blue light.

Effects of electron-withdrawing groups in imidazole-phenanthroline ligands and their influence on the photophysical properties of EuIII complexes for white light-emitting diodes

2017 ◽  
Vol 41 (18) ◽  
pp. 9826-9839 ◽  
Author(s):  
Boddula Rajamouli ◽  
Rachna Devi ◽  
Abhijeet Mohanty ◽  
Venkata Krishnan ◽  
Sivakumar Vaidyanathan
Keyword(s):  
Thin Film ◽  
Quantum Yield ◽  
White Light ◽  
Light Emitting Diode ◽  
Photophysical Properties ◽  
Red Light ◽  
Europium Complexes ◽  
Light Emitting ◽  
White Light Emitting Diodes ◽  
Phenanthroline Ligands

The red light emitting diode (LED) was fabricated by using europium complexes with InGaN LED (395 nm) and shown digital images, corresponding CIE color coordinates (red region) as well as obtained highest quantum yield of the thin film (78.7%).

(K0.5Na0.5)NbO3:Eu3+/Bi3+: a novel, highly efficient, red light-emitting material with superior water resistance behavior

RSC Advances ◽  
2015 ◽  
Vol 5 (6) ◽  
pp. 4707-4715 ◽  
Author(s):  
Qiwei Zhang ◽  
Haiqin Sun ◽  
Tao Kuang ◽  
Ruiguang Xing ◽  
Xihong Hao
Keyword(s):  
Blue Light ◽  
White Light ◽  
High Performance ◽  
Water Resistance ◽  
Light Emitting Diodes ◽  
Red Light ◽  
Light Emitting ◽  
Highly Efficient ◽  
White Light Emitting Diodes

Materials emitting red light (∼611 nm) under excitation with blue light (440–470 nm) are highly desired for fabricating high-performance white light-emitting diodes (LEDs).

scholarly journals Migratory bats are attracted by red light but not by warm-white light: Implications for the protection of nocturnal migrants

2018 ◽  
Vol 8 (18) ◽  
pp. 9353-9361 ◽  
Author(s):  
Christian C. Voigt ◽  
Katharina Rehnig ◽  
Oliver Lindecke ◽  
Gunārs Pētersons
Keyword(s):  
White Light ◽  
Red Light ◽  
Warm White Light

scholarly journals LED and UV Light Utilizing Flavonoids and Limonoids to Investigate the Effect of Post-harvest Light Irradiation

2020 ◽  
Author(s):  
Shengyu Liu
Keyword(s):  
White Light ◽  
Uv Light ◽  
Light Emitting Diode ◽  
Red Light ◽  
Principal Component ◽  
Experimental Period ◽  
Light Irradiation ◽  
Flavonoid Glycosides ◽  
Clear Correlation ◽  
Post Harvest

To investigate the effect of post-harvest light irradiation on the accumulation of flavonoids and limonoids, harvestedNewhall navel oranges were continuously exposed to light-emitting diode (LED) and ultraviolet (UV) light irradiationfor 6 days, and the composition and content of flavonoids and limonoids in the segments were determined usingUPLC-qTOF-MS at 0, 6, and 15 days after harvest. In total, six polymethoxylated flavonoids (PMFs), fiveflavoneO/C-glycosides, seven flavanone-O-glycosides, and three limonoids were identified in the segments. Theaccumulation of these components was altered by light irradiation. Red and blue light resulted in higher levels ofPMFs during exposure periods. The accumulation of PMFs was also significantly induced after white light, UVBand UVC irradiation were removed. Red and UVC irradiation induced the accumulation of flavone and flavanoneglycosides throughout the entire experimental period. Single light induced limonoid accumulation during exposureperiods, but limonoid levels decreased significantly when irradiation was removed. Principal component analysisshowed a clear correlation between PMFs and white light, between flavonoid glycosides and red light and UVC,and between limonoids and UVC. These results suggest that the accumulation of flavonoids and limonoids in citrusis regulated by light irradiation. White light, red light and UVC irradiation might be a good potential method forimproving the nutrition and flavor quality of post-harvest citrus.

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