(n.) A luminous impression produced through excitation of the retina by some cause other than the impingement upon it of rays of light, as by pressure upon the eyeball when the lids are closed. Cf. After-image.
Example Sentences:
(1) Excitatory (positive) phenomena are subjective photic sensations (phosphenes) which can be elicited by transcranial magnetic stimulation over occipital parts of the skull.
(2) Stimulation substantially above threshold may produce a second conjugate phosphene, inverted about the horizontal meridian.8.
(3) Phosphenes appear immediately when stimulation is begun, and disappear immediately upon cessation of stimulation.18.
(4) The position of phosphenes in the visual field corresponds only roughly with expectations based on classical maps showing the projection of the visual field onto the cortex.14.
(5) The configuration of the phosphene fields hints at an excitation of the primary visual cortex (Brodmann's area 17).
(6) A visual prosthesis based on electrical stimulation of the visual cortex with an array of penetrating electrodes is expected to produce pixelized visual images consisting of punctate spots of light (phosphenes).
(7) The findings of these examinations correlated best of all with the clinical picture when visual evoked potentials (latency increase, decrease of the amplitude with atrophy augmentation, interhemispheric asymmetry in chiasmal and retro-chiasmal involvement) or the critical frequency of phosphene disappearance (reliably reduced if a disease was developing) were recorded.
(8) The phenomenon of deformation phosphenes was instrumental in prompting some pre-Socratic philosophers and Plato to conceive the idea that efferent light is emitted from the eye for the purpose of vision and a 'cone of vision' is formed by interaction with the external light.
(9) Because of the variation in repeated observations of the same phosphene pair, some method is needed to provide the 'best' fitting map to the observations.
(10) The increment threshold for a small spot of light on the phosphene in the dark is some 0.5 log td higher than for the same spot on a patch of light matched in appearance to the phosphene under the same conditions.5.
(11) Our findings indicate that the psychological component of the perception of electric and magnetic phosphenes must not be underestimated.
(12) For cortical phosphenes there is no sharp flicker fusion frequency, and probably no flicker fusion frequency at all.7.
(13) From experimental work on humans in 1905 with unencapsulated radium, it is known that approximately 80% of the intensity of the radium phosphene is from the beta-ray component and approximately 20% from the gamma-ray.
(14) Experiments are described in which the phosphene produced by passing alternating current of frequency 100 Hz through the eye is matched with a patch of light having the same apparent size.2.
(15) The prosthesis would create a pixelized visual sense consisting of punctate spots of light (phosphenes).
(16) The phosphenes appear on the left or right side of the visual field depending upon the direction of the coil currents, which determines whether the visual cortex of the right or the left hemisphere is activated.
(17) Electrical stimulation of the occipital cortex resulted in discrete photic sensations or "phosphenes" in two volunteers who had been totally blind for 7 and 28 years, respectively.
(18) Patterns of up to four phosphenes produced by four electrodes have been recognized.
(19) The influence of coil position on the size of electromyographic responses and on the intensity and position of phosphenes in the binocular visual field was studied.
(20) In the medial area (10-15 mm from the midline) of the occipital lobe, stimuli above the calcarine fissure resulted in phosphenes in the lower quadrant of the visual field.
Stimulation
Definition:
(n.) The act of stimulating, or the state of being stimulated.
(n.) The irritating action of various agents (stimuli) on muscles, nerves, or a sensory end organ, by which activity is evoked; especially, the nervous impulse produced by various agents on nerves, or a sensory end organ, by which the part connected with the nerve is thrown into a state of activity; irritation.
Example Sentences:
(1) Stimulation of human leukocytes with various chemical mediators such as TPA, f-Met-Leu-Phe, LTB4, etc.
(2) The optimal size for stimulation was between 5 degrees and 12 degrees (visual angle).
(3) After stimulation with lipopolysaccharide and calcium ionophore A23187, culture supernatants of clones c18A and c29A showed cytotoxic activity against human melanoma A375 Met-Mix and other cell lines which were resistant to the tumor necrosis factor, lymphotoxin and interleukin 1.
(4) Apparently, the irradiation with visible light of a low intensity creates an additional proton gradient and thus stimulates a new replication and division cycle in the population of cells whose membranes do not have delta pH necessary for the initiation of these processes.
(5) In conclusion, in S-rats a glucose-stimulated insulin release is accompanied by an increase in IBF, but this is not observed in P-rats.
(6) Stimulation is also observed with mixtures of APC expressing DPw3 and APC expressing A1, and likewise, DPw3+ APC become stimulatory when preincubated with supernatants from A1-positive cells.
(7) We have previously shown that serotonin is present in secretory granules of frog adrenochromaffin cells; concurrently, we have demonstrated that serotonin is a potent stimulator of corticosterone and aldosterone secretion by adrenocortical cells.
(8) Cyclic AMP stimulated phosphorylation by [gamma-32P]ATP of two proteins of apparent Mr = 20,000 and 7,000 that were concentrated in sarcoplasmic reticulum, but the stimulation was markedly dependent on the presence of added soluble cyclic AMP-dependent protein kinase.
(9) We have investigated a physiological role of endogenous insulin on exocrine pancreatic secretion stimulated by a liquid meal as well as exogenous secretin and cholecystokinin octapeptide (CCK-8) in conscious rats.
(10) Whether hen's egg yolk can be used as a sperm motility stimulant in the treatment of such conditions as asthenospermia and oligospermia is subjected for further study.
(11) Some of those drugs are able to stimulate the macrophages, even in an aspecific way, via the gut associated lymphatic tissue (GALT), that is in connection with the bronchial associated lymphatic tissue (BALT).
(12) The results also suggest that the dispersed condition of pigment in the melanophores represents the "resting state" of the melanophores when they are under no stimulation.
(13) dl-Methionine stimulated the synthesis of cephalosporins when added after the growth phase.
(14) Bradykinin also stimulated arachidonic acid release in decidual fibroblasts, an effect which was potentiated in the presence of epidermal growth factor (EGF), but which was not accompanied by an increase in PGF2 alpha production.
(15) Pokeweed mitogen-stimulated rat spleen cells were identified as a reliable source of rat burst-promoting activity (PBA), which permitted development of a reproducible assay for rat bone marrow erythroid burst-forming units (BFU-E).
(16) To investigate the mechanism of enhanced responsiveness of cholesterol-enriched human platelets, we compared stimulation by surface-membrane-receptor (thrombin) and post-receptor (AlF4-) G-protein-directed pathways.
(17) Estimates of potential for gastrointestinal side effects using the rat enteropooling assay and in vivo monkey effects indicate that diarrhea will be substantially reduced with retention of uterine stimulating potency.
(18) Because it has been suggested that the lathyrogen, BAPN, may stimulate the release of proteases, the protease inhibitors Trasylol and epsilon-aminocaproic acid (EACA) were given alone or in combination to BAPN-treated rats.
(19) The present study was designed to test the hypothesis that the decreased Epi response following ET was due to 1) depletion of adrenal Epi content such that adrenomedullary stimulation would not release Epi, 2) decreased Epi release with direct stimulation, i.e., desensitization of release, or 3) decreased afferent signals generated by ET itself.
(20) Stimulation of atrial H1-receptors is suggested to directly cause an increase in Ca-channel conductance independent of intracellular cAMP content.