Perceptual learning for treating amblyopia in children based on activation of visual signal pathway Relationship of curative effects and time

BACKGROUND： Conventional methods （such as occlusion therapy, fine manipulation, complementary, and alternative medicine） take effects slowly, are time and labor consuming, and have uncertain curative effects in the treatment of amblyopia. Perceptual learning, a new method for treating amblyopia, improves the ability to process signals from the cerebral optic nerve system by specific visual stimulation and visual learning, as well as activation of the visual signal pathway utilizing brain nervous system plasticity. OBJECTIVE： This study investigated and evaluated the curative effects of perceptual learning, which can directionally increase brain plasticity, on the treatment of amblyopia in children. The relationship between curative effect and time was also analyzed. DESIGN： A self-control experiment. SETTING： Visual Science and Optometry Center, People＇s Hospital of Guangxi Zhuang Autonomous Region. PARTICIPANTS： A total of 125 amblyopic children （250 amblyopic eyes）, 73 males, 52 females, averaging （6±2） years of age, received treatment at the Visual Science and Optometry Center, People＇s Hospital of Guangxi Zhuang Autonomous Region between September 2006 and February 2007 and were recruited for this study. All children presented with no structural disease of the eyeballs. Written informed consent for therapeutic regiments was obtained from each child＇s parent. The protocol received approval from the Hospital＇s Ethics Committee. METHODS： Visual function was tested with a perceptual learning system （Research Center for Human Health and Development of Sun Yat-sen University, National Engineering Technique Research Center for Medical Care Implement） for visual noise, position noise, contour discrimination, contrast sensitivity, grating stereogram, and random-dot fusion. These tests helped to evaluate the efficiency of visual information processing of these children, and to determine the degree of defects of the optic nerve cells and the connections of visual cortical neurons. According to results of visual function tests, individualized treatment was adopted for each amblyopia patient using perceptual learning system. One course of treatment lasted one month, and treatment was performed twice every day with two training procedures （each training procedure lasted for ten minutes）. There was a ten-minute time interval between the two training procedures. The training treatment was performed in a quiet and dark environment. Visual acuity and recovery of visual function were tested every month. Original training procedure was continued or adjusted according to the results of visual function. MAIN OUTCOME MEASURES： Visual function change; relationship of curative effects and curative time. RESULTS： A total of 125 amblyopia children were included in the final analysis. The total efficiency of perceptual learning for treating amblyopia in children was 75.2%. Visual acuity began to greatly increase 3 months after treatment （P 〈 0.05）. Visual acuity was best corrected from 0.60 ± 0.23 before treatment to 0.86 ± 0.26 after treatment （P 〈 0.05）. The mean time to reach improved levels with curative effects was （2.82 ± 1.30） months, and to reach a basically cured level was （2.87 ±1.40） months. Percentage of improved visual acuity was the highest [98% （39/40）] in children that received 3 months of treatment and the lowest [55% （31/56）] in children that received 1 month of treatment （P 〈 0.05）. The percentage of basically cured levels with curative effects increased with length of learning time and was the greatest in children that received 4 months of treatment [67% （31/46）, P 〈 0.05]. CONCLUSION： Perceptual learning rapidly and remarkably improves visual function of amblyopia children; however, the curative effects are first apparent two and three months after intervention.

A hybrid flexible gas sensory system with perceptual learning

Imbuing artificial sensory system with intelligence of the biological counterpart is limited by challenges in emulating perceptual learning ability at the device level.In biological systems,stimuli from the surrounding environment are detected,transmitted,and processed by receptor,afferent nerve,and brain,respectively.This process allows the living creatures to identify the potential hazards and improve their adaptability in various environments.Here,inspired by the biological olfaction system,a gas sensory system with perceptual learning is developed.As a proof-of-concept,H2S gas with various concentrations is used as the stimulation and the stimuli will be converted to pulse-like physiological signals in the designed system,which consists of a gas sensor,a flexible oscillator,and a memristor-type artificial synapse.Furthermore,the learning ability is implemented using a supervised learning method based on k-nearest neighbors(KNN)algorithm.The recognition accuracy can be enhanced by repeating training,illustrating a great potential to be used as the neuromorphic sensory system with a learning ability for the applications in robotics.

Neural plasticity in high-level visual cortex underlying object perceptual learning

With intensive training, human can achieve impressive behavioral improvement on various perceptual tasks. This phenomenon, termed perceptual learning, has long been considered as a hallmark of the plasticity of sensory neural system. Not surprisingly, high-level vision, such as object perception, can also be improved by perceptual learning. Here we review recent psychophysical, electrophysiological, and neuroimaging studies investigating the effects of training on object selective cortex, such as monkey inferior temporal cortex and human lateral occipital area. Evidences show that learning leads to an increase in object selectivity at the single neuron level and/or the neuronal population level. These findings indicate that high-level visual cortex in humans is highly plastic and visual experience can strongly shape neural functions of these areas. At the end of the review, we discuss several important future directions in this area.

A randomized study of network-based perception learning in the treatment of amblyopia children

AIM:To compare the effectiveness of network-based perception learning(NBPL) and traditional training in the treatment of amblyopia children.METHODS:This randomized controlled clinical trial recruited 56 participants aged 4-12 y with anisometropic and/or strabismic amblyopia. Participants were randomly divided into two groups:the NBPL group(n=28) who received patching and NBPL for 3 mo, and the control group(n=28) who got 3 mo of patching and traditional training. Best-corrected visual acuity(BCVA) in the amblyopic eye and stereoacuity were measured and compared at baseline, 1, 2, and 3 mo post-randomization.RESULTS:There were no significant differences in age, gender ratio, and BCVA between the two groups at baseline. At 3 mo, most patients gained lines(2 log MAR lines on average) of BCVA in both groups except one 11-year-old girl in the control group(P<0.05). But no significant difference in BCVA improvement of the amblyopic eye between the two groups was found(P=0.725), and amblyopia resolved(BCVA of 0.1 log MAR or better or within 1 log MAR line of the fellow eye) for 13(46.4%) participants in both groups. The number of patients with improvement of stereoacuity was 25 and 13 in the NBPL group and control group(P=0.041), respectively, and a significant difference exists in the distribution of stereopsis at 3 mo between the two groups(P=0.015). Besides, in patients with measurable stereopsis improvement degree and space for improvement in the two groups, the NBPL group also achieved better stereoscopic improvement than the control group(10/11 vs 4/11, P<0.05).CONCLUSION:The NBPL system has a significant effect on the improvement of BCVA and stereoacuity of amblyopia children and is better than traditional training in terms of stereoacuity improvement. Perceptual learning visual training may play a more important role in the treatment of amblyopia in the future.

Lexical Tones and Word Learning in Mandarin-Speaking Children at Three Years of Age(Invited paper)

Unlike Indo-European languages,Mandarin relies heavily on lexical tones to distinguish word identity. Using the intermodal preferential looking paradigm, this study examined 3-year-old Mandarinspeakers＇ ability to use Mandarin lexical tones in learning new words. Results showed that when children were presented with Tone 2（rising） and Tone 4（falling）pairs, children successfully learned both words.However, when children were presented with Tone 2and Tone 3（dipping） pairs, they learned the Tone 2word but not the Tone 3 one. Children were then divided into two groups based on their learning performance on the Tone 3 word. Successful learning of Tone 3 words was observed in the high performers but not in the low performers, who consistently misused Tone 3 as Tone 2. This study showed that Mandarinspeaking 3-year-olds could use lexical tones to learn words under experimental conditions, and that the difficulty of Tone 3 acquisition may be related to its lower level of perceptual distinctiveness compared with other tones.

Improvement of visual acuity in children with anisometropic amblyopia treated with rotated prisms combined with near activity

·AIM: To evaluate the efficacy of a new modality for improving visual acuity (VA) in pediatric patients with anisometropic amblyopia. · METHODS: Retrospective and interventional case series. Medical records of 360 children with anisometropic amblyopia treated with a modality that included rotated prisms, lenses, and near activities from January 2008 to January 2012 were analyzed. Characteristics such as improvement of VA and contrast sensitivity in amblyopic eyes and resolution of amblyopia (VA ≤ 0.1logMAR or a difference of ≤ 2 lines in logMAR between the eyes) were assessed. ·RESULTS: Among the patients, the mean VA of the amblyopic eyes improved from 0.48logMAR (SD=0.16) to 0.12logMAR (SD =0.16) and the mean VA improvement was 0.36logMAR (SD =0.10, P【0.001). Resolution of amblyopia was achieved in 233 of 360 patients (64.72%). The mean time for resolution of amblyopia was 8.05 weeks (SD=4.83) or 14.14 sessions (SD=8.76). Among the study group, refraction error did not change significantly after treatment (P=0.437). We found that better baseline VA may be related to success and shorten the time to amblyopic resolution. ·CONCLUSION: VA and contrast sensitivity improved with rotated prisms, correcting lenses, and near activities in children with anisometropic amblyopia. The VA improvement by this modality was comparable to other methods. However, the time to resolution of amblyopia was shorter with this method than with other modalities. Rotated prisms combined with near acuity could provide an alternative treatment in children with anisometropic amblyopia who can’t tolerant traditional therapy method like patching.

AB067.Cholinergic enhancement of short-term patching in healthy adults

Background:Patching an eye for a period of 2 hours results in a period of plasticity where inter-ocular balance shifts in favor of the patched eye.Acetylcholine has been shown to improve visual function and augment adult neural plasticity.Here we evaluate whether administering the cholinesterase inhibitor donepezil enhances the magnitude or duration of the patching induced shift in ocular balance.Methods:We used a double-blind drug treatment design to test the effect of donepezil and patching on the shift in ocular balance.We used a well-known binocular phase combination task to measure ocular balance before and after treatment.Results:Our results demonstrate that donepezil does not enhance,and may actually reduce the magnitude and duration of the patching-induced shift in ocular balance.Conclusions:Patching induced adult neural plasticity does not appear to be modulated by the cholinergic system,however,increased dose or longer drug administration periods may yield significant results.Future studies on binocular rivalry are in the pipeline.

Improving iconic memory through contrast detection training with HOA-corrected vision

Iconic memory and short-term memory are not only crucial for perception and cognition,but also of great importance to mental health.Here,we first showed that both types of memory could be improved by improving limiting processes in visual processing through perceptual learning.Normal adults were trained in a contrast detection task for ten days,with their higher-order aberrations(HOA)corrected in real-time.We found that the training improved not only their contrast sensitivity function(CSF),but also their iconic memory and baseline information maintenance for short-term memory,and the relationship between memory and CSF improvements could be well-predicted by an observer model.These results suggest that training the limiting component of a cognitive task with visual perceptual learning could improve visual cognition.They may also provide an empirical foundation for new therapies to treat people with poor sensory memory.

Enhancement of visual perception by combining transcranial electrical stimulation and visual perceptual training

The visual system remains highly malleable even after its maturity or impairment.Our visual function can be enhanced through many ways,such as transcranial electrical stimulation(tES)and visual perceptual learning(VPL).TES can change visual function rapidly,but its modulation effect is short-lived and unstable.By contrast,VPL can lead to a substantial and long-lasting improvement in visual function,but extensive training is typically required.Theoretically,visual function could be further improved in a shorter time frame by combining tES and VPL than by solely using tES or VPL.Vision enhancement by combining these two methods concurrently is both theoretically and practically significant.In this review,we firstly introduced the basic concept and possible mechanisms of VPL and tES;then we reviewed the current research progress of visual enhancement using the combination of two methods in both general and clinical population;finally,we discussed the limitations and future directions in this field.Our review provides a guide for future research and application of vision enhancement and restoration by combining VPL and tES.