scholarly journals Excitatory conditioning to the interoceptive nicotine stimulus blocks subsequent conditioning to an exteroceptive light stimulus

2011 ◽  
Vol 221 (1) ◽  
pp. 314-319 ◽  
Author(s):  
Jennifer E. Murray ◽  
Rick A. Bevins
Keyword(s):  
Light Stimulus ◽  
Excitatory Conditioning

Brightness In The Photopic Range: Psychophysical Modelling With Blue-sensitive Retinal Signals

2020 ◽  
pp. 9-24
Author(s):  
Peter Bodrogi ◽  
Xue Guo ◽  
Tran Quoc Khanh
Keyword(s):  
Ganglion Cells ◽  
Light Stimulus ◽  
Spectral Radiance ◽  
Psychophysical Experiment ◽  
Retinal Ganglion ◽  
Reasonable Accuracy ◽  
Brightness Perception ◽  
Content Model ◽  
The Difference ◽  
Cone Signal

The brightness perception of a large (41°) uniform visual field was investigated in a visual psychophysical experiment. Subjects assessed the brightness of 20 light source spectra of different chromaticities at two luminance levels, Lv=267.6 cd/m2 and Lv=24.8 cd/m2. The resulting mean subjective brightness scale values were modelled by a combination of the signals of retinal mechanisms: S-cones, rods, intrinsically photosensitive retinal ganglion cells (ipRGCs) and the difference of the L-cone signal and the M-cone signal. A new quantity, “relative spectral blue content”, was also considered for modelling. This quantity was defined as “the spectral radiance of the light stimulus integrated with the range (380–520) nm, relative to luminance”. The “relative spectral blue content” model could describe the subjective brightness perception of the observers with reasonable accuracy.

scholarly journals 111 Artificial Light-Triggered Sleep Deprivation May Lead to Allodynia in Rodent Model

SLEEP ◽  
2021 ◽  
Vol 44 (Supplement_2) ◽  
pp. A45-A46
Author(s):  
Skyler Kanegi ◽  
Armen Akopian
Keyword(s):  
Sleep Deprivation ◽  
Light Exposure ◽  
Light Stimulus ◽  
Continuous Light ◽  
Artificial Light ◽  
Light Cycle ◽  
Tissue Samples ◽  
Mechanical Threshold ◽  
Dim Light ◽  
Von Frey Filaments

Abstract Introduction The combination of artificial light and lack of exposure to natural light can delay the circadian clock, dysregulate the circadian cycle, and decrease alertness upon waking. This effect has been especially significant during the COVID-19 pandemic, where overexposure to artificial light at improper hours has contributed to increased rates of clinical insomnia. Artificial light may also contribute to concomitant neurological conditions such as primary headache, but the mechanisms by which light triggers sleep deprivation-induced headache are not well-understood. Methods To measure pain sensitivity, we habituated 13 wild-type male mice to von Frey filaments applied to the periorbital area until there was no response to 0.6g stimulus. We then applied 5 lux of continuous dim light to mice during their usual 12-hour dark cycle. The 12-hour light cycle remained unchanged with 200 lux continuous light. Three groups of mice experienced the dim light stimulus for one, three, or five consecutive days. Ambulation and rest activity were measured using SOF-812 Activity Monitor machines. After the experiment concluded, we waited 24 hours and measured mechanical threshold using von Frey filaments at 1, 3, 5, 8, and every 3 days subsequently until mice no longer responded to 0.6g stimulus. Results Artificial light triggered changes in circadian behavior including increased number of rest periods during 12-hour dark (dim light) cycle and shortened sleep duration during 12-hour light cycle. Following the artificial light stimulus, there was a significant decrease in mechanical threshold (P<0.05), representing allodynia. The one-day group displayed one day of significant allodynia. The three-day group displayed three days of significant allodynia. The five-day group displayed five days of significant allodynia. Conclusion Artificial light may trigger circadian dysregulation, and the duration of artificial light exposure seemed to be directly correlated to the duration of allodynia up to one week after the stimulus was removed. We will repeat these experiments and analyze CNS and PNS tissue samples to understand the underlying physiological and biochemical bases of how artificial light triggers sleep deprivation-induced headache. This knowledge could increase our understanding of the pathophysiology and comorbidity of sleep deprivation and headache. Support (if any) Funding was received from the National Institute of Health (NS104200).

Strength of Suppression in Binocular Rivalry Immediately after Onset and Offset of Suppressing Pattern

1987 ◽  
Vol 65 (2) ◽  
pp. 515-523 ◽  
Author(s):  
Tamotsu Sohmiya ◽  
Kazuko Sohmiya
Keyword(s):  
Human Brain ◽  
Binocular Rivalry ◽  
Light Stimulus ◽  
Physiological Data ◽  
Temporal Properties ◽  
Dichoptic Viewing

If the dichoptic viewing method is used to analyze functions of the human brain rather than binocular rivalry itself, temporal properties of suppression come up as an important problem. To clarify the properties, a method in which test and suppressing patterns can be presented on any temporal condition was devised. When the suppressing pattern was flickered, the strength of suppression immediately after the onset of the pattern approached a maximum at the intercycle interval of 3 sec. It also increased with the increasing duration of exposure and reached a maximum at about 100 msec. The strength of suppression immediately after the offset decreased rapidly but continuously as time went on. These results indicate that the on-effect is produced by the presentation of the suppressing pattern, not the off-effect by its removal, whereas physiological data generally show the strong effect both at “on” and “off” of a light stimulus.

The rod bipolar cell of the mammalian retina

1991 ◽  
Vol 7 (1-2) ◽  
pp. 99-112 ◽  
Author(s):  
Heinz Wässle ◽  
Masayuki Yamashita ◽  
Ursula Greferath ◽  
Ulrike Grünert ◽  
Frank Müller
Keyword(s):  
Chloride Channels ◽  
Light Stimulus ◽  
Bipolar Cells ◽  
Immunocytochemical Staining ◽  
Nonselective Cation Channel ◽  
Light Responses ◽  
Kinase C ◽  
Mammalian Retina ◽  
Approaches To Study ◽  
Rod Bipolar Cells

AbstractThree approaches to study the function of mammalian rod bipolar cells are described. Extracellular recordings from the intact cat eye under light- and dark-adapted conditions showed that in dark-adapted retina all light responses can be blocked by 2-amino-4-phosphonobutyrate (APB). Immunocytochemical staining with an antibody against protein kinase C (PKC) labeled rod bipolar cells in all mammalian retinae tested. When rat retinae were dissociated, PKC immunoreactivity was also found in isolated bipolar cells and could be used for their identification as rod bipolars. Patch-clamp recordings were performed from such dissociated rod bipolar cells and their responses to APB were measured. APB closed a nonselective cation channel in the cell membrane. The actions of GABA and glycine were also tested and both opened chloride channels in dissociated rod bipolar cells. These results suggest that rod bipolar cells are depolarized by a light stimulus and that GABA as well as glycine modulate their light responses.

Cross-species Transcriptomes Reveal Species-specific and Shared Molecular Adaptations for Plants Development on Iron-rich Rocky Outcrops Soils

2021 ◽  
Author(s):  
Mariana Costa Dias ◽  
Cecílio Caldeira ◽  
Markus Gastauer ◽  
Silvio Ramos ◽  
Guilherme Oliveira
Keyword(s):  
Circadian Rhythm ◽  
Differential Expression ◽  
Native Species ◽  
Molecular Mechanisms ◽  
Light Stimulus ◽  
Differential Expression Analysis ◽  
Common Mechanism ◽  
Dependent Manner ◽  
Rocky Outcrops ◽  
Species Specific

Abstract BackgroundCanga is the Brazilian term for the savanna-like vegetation harboring several endemic species on iron-rich rocky outcrops, usually considered for mining activities. Parkia platycephala Benth. and Stryphnodendron pulcherrimum (Willd.) Hochr. naturally occur in the cangas of Serra dos Carajás (eastern Amazonia, Brazil) and the surrounding forest, indicating high phenotypic plasticity. The morphological and physiological mechanisms of the plants’ establishment in the canga environment are well studied, but the molecular adaptative responses are still unknown. We aimed to identify molecular mechanisms that allow the establishment of these plants in the canga environment.ResultsPlants were grown in canga and forest substrates collected in the Carajás Mineral Province. RNA was extracted from pooled leaf tissue, and RNA-seq paired-end reads were assembled into representative transcriptomes for P. platycephala and S. pulcherrimum containing 31,728 and 31,311 primary transcripts, respectively. We identified both species-specific and core molecular responses in plants grown in the canga substrate using differential expression analyses. In the species-specific analysis, we identified 1,112 and 838 differentially expressed genes for P. platycephala and S. pulcherrimum, respectively. Enrichment analyses showed unique biological processes and metabolic pathways affected for each species. Comparative differential expression analysis was based on shared single-copy orthologs. The overall pattern of ortholog expression was species-specific. Even so, almost 300 altered genes were identified between plants in canga and forest substrates, responding the same way in both species. The genes were functionally associated with the response to light stimulus and the circadian rhythm pathway.ConclusionsPlants possess species-specific adaptative responses to cope with the substrates. Our results also suggest that plants adapted to both canga and forest environments can adjust the circadian rhythm in a substrate-dependent manner. The circadian clock gene modulation might be a central mechanism regulating the plants’ development in the canga substrate in the studied legume species. The mechanism may be shared as a common mechanism to abiotic stress compensation in other native species.

scholarly journals A quiescent state following mild sensory arousal in Caenorhabditis elegans is potentiated by stress

2019 ◽  
Author(s):  
Patrick D. McClanahan ◽  
Jessica M. Dubuque ◽  
Daphne Kontogiorgos-Heintz ◽  
Ben F. Habermeyer ◽  
Joyce H. Xu ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Light Exposure ◽  
Light Stimulus ◽  
Low Frequency ◽  
Behavioral Responses ◽  
Quiescent State ◽  
Sleep State ◽  
C Elegans ◽  
Epidermal Growth ◽  
Cellular Stressors

AbstractAn animal’s behavioral and physiological response to stressors includes changes to its responses to stimuli. How such changes occur is not well understood. Here we describe a Caenorhabditis elegans quiescent behavior, post-response quiescence (PRQ), which is modulated by the C. elegans response to cellular stressors. Following an aversive mechanical or blue light stimulus, worms respond first by briefly moving, and then become more quiescent for a period lasting tens of seconds. PRQ occurs at low frequency in unstressed animals, but is more frequent in animals that have experienced cellular stress due to ultraviolet light exposure as well as in animals following overexpression of epidermal growth factor (EGF). PRQ requires the function of the carboxypeptidase EGL-21 and the calcium-activated protein for secretion (CAPS) UNC-31, suggesting it has a neuropeptidergic mechanism. Although PRQ requires the sleep-promoting neurons RIS and ALA, it is not accompanied by decreased arousability, and does not appear to be homeostatically regulated, suggesting that it is not a sleep state. PRQ represents a simple, tractable model for studying how neuromodulatory states like stress alter behavioral responses to stimuli.

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