Detection of Juvenile Sleep Deprivation by Stochastic Optimization of Pupillographic Records

Summary Objective: To address the challenging problem of measuring juvenile sleep deprivation, we test the hypothesis that a pupillographic method found successful for adult narcoleptics might also discriminate between sleep deprived juveniles acting as their own controls. Methods: A linear, nonstationary model relating pupillary diameter and a random photic stimulus are estimated by recursive regressions from pupillographic records of 8 juveniles of median age 7 years acting as their own rested controls. The estimated pupillary impulse response noise functions are stochastically optimized using the Kullback divergence measure to maximally separate the sleep deprived records from the control records. Results: Both the average and covariance statistics of the estimated pupillary noise functions exhibit statistically significant differences between sleep deprived and rested subjects. The main result is that sleep deprivation decreases pupillary noise variance; a finding consistent with a previous study of adult narcoleptics. Further, it was found that virtually the same stochastic parameters were optimal for the juvenile sleep deprived data and for the previous adult narcoleptic study. Conclusions: Although our results are preliminary, the consistent reduction of pupillary noise appears to justify a comprehensive clinical trial across a broad range of age classes. In addition, the finding that the same parameters stochastically optimze both juvenile and adult recordings suggests the procedure holds promise as a clinical test which could produce sleep deprivation measures simultaneous with data collection.

Enhancement of REM sleep during extraocular light exposure in humans

This study examined the effects on sleep of light administered to an extraocular site. A 3-h photic stimulus was applied to the popliteal region during sleep in 14 human subjects. Each subject also underwent a control stimulus condition during a separate laboratory session. The proportion of rapid eye movement (REM) sleep during the 3-h light administration session increased by an average of 31% relative to the control condition. The frequency but not the duration of REM episodes was altered during light exposure, thereby shortening the REM/non-REM (NREM) cycle length. No other sleep stages were significantly affected during light administration nor was sleep architecture altered after the light-exposure interval. These results confirm that extraocular light is transduced into a signal that is received and processed by the human central nervous system. In addition, they expand to a novel sensory modality previous findings that REM sleep can be enhanced by sensory stimulation.

The Pupillary Light Reflex in Borderline Diabetics

Computerized IR videopupillography, using an open-loop photic stimulator, was used to compare the reflexes of borderline diabetics with overt non-insulin-dependent diabetics and with age- and sex-matched non-diabetic healthy controls. The patients were all male, aged 41–59 years. Overt non-insulin-dependent diabetics in their 40s had a smaller pupillary area and pupillary diameter prior to photic stimulus compared with borderline diabetics and healthy controls. Overt non-insulin-dependent diabetics in their 50s had a lower pupillary area and pupillary diameter prior to photic stimulus, maximum velocity and acceleration of constriction and maximum velocity of dilation than did borderline diabetics or controls. The only abnormality observed among borderline diabetics compared to controls was a smaller amplitude of constriction in response to light in patients in their 50s. Amplitude of constriction in response to light and velocity of constriction measurements of borderline diabetics, however, were considerably more frequently abnormal than were those of controls. The frequency of abnormal pupillary diameter prior to photic stimulus, maximum velocity of dilation and acceleration of constriction was higher in overt non-insulin-dependent diabetics than in borderline diabetics. The results indicate that borderline diabetics have autonomic neuropathy before the disease becomes overt. The importance of the pupillary light reflex examination is discussed.

Persistence of Synaptic Vesicles After Photodynamic Abolition of Quantal Release at the Neuromuscular Junction of the Lizard

We have used rose bengal (RB) to study the ultrastructural and physiological effects of in vivo photooxidation of the presynaptic terminal of the neuromuscular junction. Rose bengal (RB) is a powerful xanthine photosensitizer capable of inducing fairly selective photooxidation of histidinyl residues of proteins when exposed to light in the present of O2 (from air) and pH near 7.0. Recent observations by Politoff and Lifschitz show that RB is taken up spontaneously by the nerve terminal and selectively accumulated in the presynaptic region; after uptake of RB, illumination of the presynaptic region with a microscopic photic stimulus (1.3 x 103 erg) causes a brief (15 min) and small burst (3.0 x 103 total release) of miniature end plate potentials (m.e.p.p.), followed by total abolition of m.e.p.p.'s, in spite of preservation of postsynaptic sensitivity.