hippus


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hippus

 [hip´us]
abnormal exaggeration of the rhythmic contraction and dilation of the pupil, independent of changes in illumination or in fixation of the eyes.

hip·pus

(hip'ŭs),
Intermittent pupillary dilation and constriction, independent of illumination, convergence, or psychic stimuli.
[G. hippos, horse, from a fancied suggestion of galloping movements]

hippus

A spasm of the iris, resulting in exaggerated rhythmic contractions and dilatations of the pupil that are not consonant with accommodation and light. See Hiccup.

hip·pus

(hip'ŭs)
Intermittent pupillary dilation and constriction, independent of illumination, convergence, or psychic stimuli.
[G. hippos, horse, from a fancied suggestion of galloping movements]

hippus

Small rhythmic variations in the size of the pupils. They are present in everybody and increase slightly at high luminances. The frequency of these oscillations is about 1.4 Hz. Hippus may also be associated with systemic disorders such as multiple sclerosis, neurosyphilis and myasthenia gravis.
References in periodicals archive ?
Pupillary oscillations in the low-frequency range (<0.8 Hz, known as the "hippus" range) are enhanced after monocular deprivation, compared to the baseline measure acquired before applying the eye-patch (Figure 4(a); paired t-test t(9) = 6.278, p < 0.001).
To test whether the effects of deprivation on binocular rivalry and slow pupil oscillations are related, we measured Spearman's correlation coefficient (Rho) between the binocular rivalry Deprivation Index (see (1)) and the increased power in the hippus range (Figure 3(b)).
The correlation with PUI is weaker than with hippus power (Spearman's Rho = -0.418, p = 0.232), indicating that FFT power gives a more precise quantification of the pupillary behavior.
We find that the dynamics of the pupil are altered after MD, with increased amplitude of low-frequency oscillations, that is, enhanced hippus. This effect is specific for oscillations in the "hippus" range (slower than about 1 Hz, a time scale that is very similar to the frequency of perceptual oscillations during binocular rivalry), whereas faster oscillations (in the delta or theta ranges) are indistinguishable before/after MD, and so is the average pupil diameter.
The most important aspect of our results is the tight correlation between the effects of MD on our two very different measures, obtained minutes apart with different apparatus: pupillary hippus and increased eye-dominance of the deprived eye during binocular rivalry.
We speculate that the key to understanding this close relationship between pupillary hippus and plasticity lies within the complex neural circuits that regulate the balance between inhibition and excitation in the cortex, where the neuromodulator norepinephrine plays a key role.
Legriel, "Pupillary hippus in nonconvulsive status epilepticus," Epileptic Disorders, vol.
The stone seen in photograph 1 (on page 524) is from the town of Fiq in the southern district of Hippus, and contains the opening portion of the usual formula, which we can complete, though the names of the towns are lost: "Diocletian and Maximian, Augusti, and Constantius and Maximian, most worthy [Caesars, ordered that this stone demarking the boundaries of N.
Photos and descriptions that follow are of representative artifacts recovered in five of the Golan sites: El-'Al (eastward from Hippus/Susita in the south), `Ein Nashot (close to the Jordan River, north of the Sea of Galilee), El-Kursi (just above Hippus, near the Sea of Galilee), Ramsaniyye (eastern-central Gaulanitis), and Fiq (a town only a few kilometers from Hippus).
Further, far from declining into a kind of dormancy after the period in which Josephus wrote, Gaulanitis and the two city territories of Caesarea Philippi/Paneas and Hippus seem to have enjoyed a population spurt in the late Roman and early Byzantine eras, helped by the olive oil market.