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It has long been debated whether the analysis of global and local stereoscopic depth is performed by a single system or by separate systems. Global stereopsis requires the visual system to solve a complex binocular matching problem to obtain a coherent percept of depth. In contrast, local stereopsis requires only a simple matching of similar image features. In this preliminary study, we recruited five adults with amblyopia who lacked global stereopsis and trained them on a computerized local stereopsis depth task for an average of 12 h. Three out of five (60%) participants recovered fine global stereoscopic vision through training. Those who recovered global stereopsis reached a learning plateau more quickly on the local stereopsis task, and they tended to start the training with better initial local stereopsis performance, to improve more on local stereopsis with training, and to have less severe amblyopia. The transfer of learning from local stereopsis to global stereopsis is compatible with an interacting two-stage model., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Chopin, Silver, Sheynin, Ding and Levi.)

The endogenous neurotransmitter acetylcholine (ACh) is known to affect the excitatory/inhibitory (E/I) balance of primate visual cortex, enhancing feedforward thalamocortical gain while suppressing corticocortical synapses. Recent advances in the study of the human visual system suggest that ACh is a likely component underlying interocular interactions. However, our understanding of its precise role in binocular processes is currently lacking. Here we use binocular rivalry as a probe of interocular dynamics to determine ACh's effects, via the acetylcholinesterase inhibitor (AChEI) donepezil, on the binocular visual system. A total of 23 subjects (13 male) completed two crossover experimental sessions where binocular rivalry measurements were obtained before and after taking either donepezil (5 mg) or a placebo (lactose) pill. We report that enhanced cholinergic potentiation attenuates perceptual suppression during binocular rivalry, reducing the overall rate of interocular competition while enhancing the visibility of superimposition mixed percepts. Considering recent evidence that perceptual suppression during binocular rivalry is causally modulated by the inhibitory neurotransmitter GABA, our results suggest that cholinergic activity counteracts the effect of GABA with regards to interocular dynamics and may modulate the inhibitory drive within the visual cortex. SIGNIFICANCE STATEMENT Our research demonstrates that the cholinergic system is implicated in modulating binocular interactions in the human visual cortex. Potentiating the transmission of acetylcholine (ACh) via the cholinergic drug donepezil reduces the extent to which the eyes compete for perceptual dominance when presented two separate, incongruent images., (Copyright © 2020 the authors.)

A few hours of monocular patching temporarily enhances the deprived eye's contribution to binocular vision, constituting a form of adult brain plasticity. Although the mechanism for this plasticity is currently unknown, several imaging studies present evidence that monocular deprivation achieves its effects by changing excitatory-inhibitory balance in the visual cortex. Much of the past work on adult monocular patching utilized binocular rivalry to quantify the patching-induced shift in perceptual eye dominance, extracting periods of exclusive visibility (in which one eye's signal is suppressed from perception) to assess each eye's contribution to binocular vision while overlooking the occurrence of mixed visibility (in which information from both eyes is combined). In this paper, we discuss two experiments to investigate the effects of short-term monocular occlusion on the relative predominance of mixed and exclusive percepts during binocular rivalry. In addition to the known perceptual eye-dominance shift, we hypothesized patching would also increase the perception of mixtures during rivalry due to deprivation-induced changes in excitatory-inhibitory balance. Our data point to two previously unknown effects of monocular deprivation: (a) a significant increase in the overall fraction and median duration of mixed visibility during rivalry that is detectable up to at least an hour after removing the patch and (b) the overall fraction of superimposition; rather than piecemeal, mixed percepts are specifically enhanced after monocular deprivation. In addition to strengthening the contribution of the deprived eye, our results show that temporary monocular patching enhances the visibility of fused binocular percepts, likely the result of attenuated interocular inhibition.

A few hours of monocular deprivation with a diffuser eye patch temporarily strengthens the contribution of the deprived eye to binocular vision. This shift in favor of the deprived eye is characterized as a form of adult visual plasticity. Studies in animal and human models suggest that neuromodulators can enhance adult brain plasticity in general. Specifically, acetylcholine has been shown to improve certain aspects of visual function and plasticity in adulthood. We investigated whether a single administration of donepezil (a cholinesterase inhibitor) could further augment the temporary shift in perceptual eye dominance that occurs after 2 h of monocular patching. Twelve healthy adults completed two experimental sessions while taking either donepezil (5 mg, oral) or a placebo (lactose) pill. We measured perceptual eye dominance using a binocular phase combination task before and after 2 h of monocular deprivation with a diffuser eye patch. Participants in both groups demonstrated a significant shift in favor of the patched eye after monocular deprivation, however our results indicate that donepezil significantly reduces the magnitude and duration of the shift. We also investigated the possibility that donepezil reduces the amount of time needed to observe a shift in perceptual eye dominance relative to placebo control. For this experiment, seven subjects completed two sessions where we reduced the duration of deprivation to 1 h. Donepezil reduces the magnitude and duration of the patching-induced shift in perceptual eye dominance in this experiment as well. To verify whether the effects we observed using the binocular phase combination task were also observable in a different measure of sensory eye dominance, six subjects completed an identical experiment using a binocular rivalry task. These results also indicate that cholinergic enhancement impedes the shift that results from short-term deprivation. In summary, our study demonstrates that enhanced cholinergic potentiation interferes with the consolidation of the perceptual eye dominance plasticity induced by several hours of monocular deprivation.

Polyfurans have never been established as useful conjugated polymers, as previously they were considered to be inherently unstable and poorly conductive. Here, we show the preparation of stable and conducting polyfuran films by electropolymerization of a series of oligofurans of different chain lengths substituted with alkyl groups. The polyfuran films show good conductivity in the order of 1 S cm -1 , good environmental and electrochemical stabilities, very smooth morphologies (roughness 1-5 nm), long effective conjugation lengths, well-defined spectroelectrochemistry and electro-optical switching (in the Vis-NIR region), and have optical band-gaps in the range of 2.2-2.3 eV. A low oxidation potential needed for polymerization of oligofurans (compared to furan) is a key factor in achievement of improved properties of polyfurans reported in this work. DFT calculations and experiments show that polyfurans are much more rigid than polythiophenes, and alkyl substitution does not disturb backbone planarity and conjugation. The obtained properties of polyfuran films are similar or superior to the properties of electrochemically prepared poly(oligothiophene)s under similar conditions.

The crystal structures of three 1:2 inclusion compounds that consist of host molecule 2,5-diphenylhydroquinone (C(18)H(14)O(2)) and the guest molecules 2-pyridone (C(5)H(5)NO), 1,3-diphenyl-2-propen-1-one (chalcone, C(15)H(12)O) and 1-(4-methoxyphenyl)-3-phenyl-2-propen-1-one (4'-methoxychalcone, C(16)H(14)O(2)) were determined in order to study the ability of guest molecules in inclusion compounds to undergo photoreaction. All of the crystals were found to be photoresistant. The three inclusion compounds crystallize in triclinic space group P1. In each case, the host/guest ratio is 1:2, with the host molecules occupying crystallographic centers of symmetry and the guest molecules occupying general positions. The guest molecules in each of the inclusion compounds are linked to the host molecules by hydrogen bonds. In the inclusion compound where the guest molecule is pyridone, the host molecule is disordered so that the hydroxy groups are distributed between two different sites, with occupancies of 0.738 (3) and 0.262 (3). The pyridone molecules form dimers via N-H...O hydrogen bonds.