Experience-dependent recovery of vision following chronic deprivation amblyopia. Hai-Yan He, Baisali Ray, Katie Dennis and Elizabeth M.

Transcription

1 Experience-dependent recovery of vision following chronic deprivation amblyopia Hai-Yan He, Baisali Ray, Katie Dennis and Elizabeth M. Quinlan a Deprived eye Non-deprived VCtx * * b Non-deprived VCtx Supplementary Figure 1. Dark exposure in adulthood allowed recovery of function following chronic. a. In the non-deprived VCtx, chronic induced a significant decrease in VEP amplitudes in response to stimulation of the deprived eye (p <.1, t-test vs NR), which recovered when was followed by or (norm VEP amp: control = 2.6 ±.24, = 5 ±.19, - = 1.1 ±.2, - = 1.11 ±.11, - =.97 ±.11, -- = 1.94 ±.2, -- = 2.54 ±.34). Oneway ANOVA (F(5,44) = 8.415, p <.1), * = p <.5 vs.. b. Chronic and subsequent manipulations of visual experience did not regulate the VEP in response to stimulation of the non-deprived eye in the non-deprived VCtx. One-way ANOVA (F(5, 44) = 89, p =.38).

2 a Chronic deprived eye Log of spatial frequency (cycles deg -1) b Monocular spatial acuity (cycles deg -1 ) Rearing condition Supplementary Figure 2. Estimation of spatial acuity with VEPs. a. Log of the spatial frequency of the visual stimulus vs. VEP amplitude in response to stimulation of the chroinically-deprived and non-deprived eye recorded in the hemisphere dominated by that eye. Spatial acuity was estimated by extrapolating the linear regression to zero VEP amplitude. Chronically-deprived eye =.26 cycles deg -1, non-deprived eye = cycles deg -1. b. No change in spatial acuity in the non-deprived eye was observed across experimental conditions (one-way ANOVA (F(5,26) = 1.397, p =.26).

3 -1) Monocular spatial acuity (cycles deg NR 1 Trial 1 Trial 2 day 2 8 Trial 3 day Spatial frequency (cycles deg -1) Days of binocular vision after normal rearing Deprived eye Supplementary Figure 3. Two-choice visual discrimination task revealed no recovery of spatial acuity in the absence of dark exposure. Monocular spatial acuity in non-deprived eye was unchanged following 1 days of normal rearing without exposure to the task (NR =.76 ±.8 cycles deg -1, n = 8). No measurable spatial acuity in the deprived eye was observed after 7 weeks of. Inset: % correct choices vs. spatial frequency of visual stimulus in a single adult subject. The highest spatial frequency at which the subject performed 6% correct choices was the spatial acuity for that trial, and was similar across trials on consecutive days (trials 1 and 2), and a trial that followed 1 days without exposure to the task (trial 3 day 13).

4 Supplementary Methods Long Evans rats were raised with 12 hr light: 12 hr dark per day until adulthood (P7-1) before receiving brief (3 days) via lid suture (4). 3-1 days of dark exposure in a light-tight dark room may precede the brief. Chronic lid suture began at eye opening (~P13) and proceeded to adulthood (P7-P1). Chronic may be followed by binocular vision (opening the deprived eye) or reverse occlusion (opening the deprived eye and closing the non-deprived eye), which may be preceded by 1 days dark exposure. All procedures conformed to the guidelines of the U.S. Department of Health and Human Services and the University of Maryland Institutional Animal Care and Use Committee. VEP recordings: Visually evoked potentials (VEPs) were recorded with tungsten microelectrodes (.1 MΩ; MPI, Gaithersburg, ) relative to a ground screw in the frontal bone and a reference electrode in dorsal neck muscle. The dura covering the binocular visual cortex (V1b; ~7. mm posterior to bregma and 5 mm lateral to the midline) was exposed through a 3mm diameter hole in the skull following urethane anesthesia (1.6g/kg i.p.). Electrode placement in V1b was confirmed by capturing a VEP in response to stimulation of the ipsilateral eye. The visual stimuli were full screen vertical square wave gratings of.4 cycles deg 1 reversing at 1 Hz, with 96.28% maximal contrast, presented on a computer monitor 25 cm from eyes, in a darkened room. The amplitude of the primary positive component of the VEP (~15 ms latency) was amplified (1X), filtered (.5-3 Hz band pass followed by 6 Hz low pass) and averaged (1 trials) in synchrony with the stimulus using ENFANT software (Enfant 41, NeuroScientific Corp., Farmingdale, NY). VEP amplitudes were normalized to noise at that recording site, which was the average field potential recorded in response to a blank screen. For spatial acuity estimation, VEPs were recorded from the hemisphere contralateral to the stimulated eye. The VEP amplitude (normalized to the maximal response recorded within that session) was plotted against the log of the spatial frequency of the visual stimulus. The spatial frequency extrapolated to zero amplitude of the linear regression through the last 5-8 data points was reported as estimated spatial acuity (adapted from 11).

5 Visual discrimination: Spatial acuity was assessed behaviorally with a water-based 2 choice visual discrimination task (developed by Prusky and colleagues, University of Lethbridge, Alberta, Canada), in a plexiglass box (152 x 94 x 76 cm), painted flat black on 3 sides, filled to a height of 36 cm (~14 gallons). Visual stimuli, presented on monitors mounted to the outside of the unpainted end of the box (Lacie 319 LCD, Hillsboro, OR), were generated by Vista 2.2 software (Cerebral Mechanics, Lethbridge, Alberta, Canada). Subjects learned to associate a hidden escape platform (positive stimulus) with a high contrast vertical sinusoidal grating, and the negative stimulus (absence of escape platform) with a grey screen with equal luminance (75 cd/m 2 ), white balance (5K), gamma value (1.8) and contrast (1%; calibrated daily with Lacie Blue eye pro, version 3.4, Hillsboro, OR), which were presented to the left and right screens in pseudo-random order. Short (17.8 cm), medium (35.6 cm) and long dividers (53.4 cm) were gradually introduced between the two monitors to increase the visual discrimination choice point. Once subjects reached the learning criterion (3 correct choices over 3 consecutive trials) at a spatial frequency of.129 cycles deg 1, the spatial frequency of the visual stimulus was increased by increments of.64 cycles deg 1. At spatial frequencies.482 cycles deg -1, testing at the next higher spatial frequency followed a single successful trial. At spatial frequencies >.482 cycles deg 1, a success rate of 6% over 5 trials was required before moving to the next spatial frequency. The highest spatial frequency at which the subject performed 6% correct (out of 5 trials) was the spatial acuity for that trial. Statistical analysis: Student one-tailed t-tests were used to evaluate differences between two independent experimental groups. One-way ANOVAs were used to test for differences among three or more independent experimental groups. F crit was significant when > than F test calculated for the degrees of freedom between groups (factor) and within groups (residual) for each experiment. Fisher s PLSD post hoc comparison was used to identify the source of significant differences, when appropriate.