How to construct liquid-crystal spectacles to control vision of real-world objects and environments.

A major challenge in studying naturalistic vision lies in controlling stimulus and scene viewing time. This is especially the case for studies using real-world objects as stimuli (rather than computerized images) because real objects cannot be "onset" and "offset" in the same way that images can be. Since the late 1980s, one solution to this problem has been to have the observer wear electro-optic spectacles with computer-controlled liquid-crystal lenses that switch between transparent ("open") and translucent ("closed") states. Unfortunately, the commercially available glasses (PLATO Visual Occlusion Spectacles) command a high price tag, the hardware is fragile, and the glasses cannot be customized. This led us to explore how to manufacture liquid-crystal occlusion glasses in our own laboratory. Here, we share the products of our work by providing step-by-step instructions for researchers to design, build, operate, and test liquid-crystal glasses for use in experimental contexts. The glasses can be assembled with minimal technical knowledge using readily available components, and they can be customized for different populations and applications. The glasses are robust, and they can be produced at a fraction of the cost of commercial alternatives. Tests of reliability and temporal accuracy show that the performance of our laboratory prototype was comparable to that of the PLATO glasses. We discuss the results of our work with respect to implications for promoting rigor and reproducibility, potential use cases, comparisons with other liquid-crystal shutter glasses, and how users can find information regarding future updates and developments.

Simultaneous CRISPR/Cas9-mediated editing of cassava eIF4E isoforms nCBP-1 and nCBP-2 reduces cassava brown streak disease symptom severity and incidence.

Cassava brown streak disease (CBSD) is a major constraint on cassava yields in East and Central Africa and threatens production in West Africa. CBSD is caused by two species of positive-sense RNA viruses belonging to the family Potyviridae, genus Ipomovirus: Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). Diseases caused by the family Potyviridae require the interaction of viral genome-linked protein (VPg) and host eukaryotic translation initiation factor 4E (eIF4E) isoforms. Cassava encodes five eIF4E proteins: eIF4E, eIF(iso)4E-1, eIF(iso)4E-2, novel cap-binding protein-1 (nCBP-1), and nCBP-2. Protein-protein interaction experiments consistently found that VPg proteins associate with cassava nCBPs. CRISPR/Cas9-mediated genome editing was employed to generate ncbp-1, ncbp-2, and ncbp-1/ncbp-2 mutants in cassava cultivar 60444. Challenge with CBSV showed that ncbp-1/ncbp-2 mutants displayed delayed and attenuated CBSD aerial symptoms, as well as reduced severity and incidence of storage root necrosis. Suppressed disease symptoms were correlated with reduced virus titre in storage roots relative to wild-type controls. Our results demonstrate the ability to modify multiple genes simultaneously in cassava to achieve tolerance to CBSD. Future studies will investigate the contribution of remaining eIF4E isoforms on CBSD and translate this knowledge into an optimized strategy for protecting cassava from disease.

Graspable Objects Grab Attention More Than Images Do.

The opportunity an object presents for action is known as an affordance. A basic assumption in previous research was that images of objects, which do not afford physical action, elicit effects on attention and behavior comparable with those of real-world tangible objects. Using a flanker task, we compared interference effects between real graspable objects and matched 2-D or 3-D images of the items. Compared with both 2-D and 3-D images, real objects yielded slower response times overall and elicited greater flanker interference effects. When the real objects were positioned out of reach or behind a transparent barrier, the pattern of response times and interference effects was comparable with that for 2-D images. Graspable objects exert a more powerful influence on attention and manual responses than images because of the affordances they offer for manual interaction. These results raise questions about whether images are suitable proxies for real objects in psychological research.

Naturalistic Object Representations Depend on Distance and Size Cues.

Egocentric distance and real-world size are important cues for object perception and action. Nevertheless, most studies of human vision rely on two-dimensional pictorial stimuli that convey ambiguous distance and size information. Here, we use fMRI to test whether pictures are represented differently in the human brain from real, tangible objects that convey unambiguous distance and size cues. Participants directly viewed stimuli in two display formats (real objects and matched printed pictures of those objects) presented at different egocentric distances (near and far). We measured the effects of format and distance on fMRI response amplitudes and response patterns. We found that fMRI response amplitudes in the lateral occipital and posterior parietal cortices were stronger overall for real objects than for pictures. In these areas and many others, including regions involved in action guidance, responses to real objects were stronger for near vs. far stimuli, whereas distance had little effect on responses to pictures-suggesting that distance determines relevance to action for real objects, but not for pictures. Although stimulus distance especially influenced response patterns in dorsal areas that operate in the service of visually guided action, distance also modulated representations in ventral cortex, where object responses are thought to remain invariant across contextual changes. We observed object size representations for both stimulus formats in ventral cortex but predominantly only for real objects in dorsal cortex. Together, these results demonstrate that whether brain responses reflect physical object characteristics depends on whether the experimental stimuli convey unambiguous information about those characteristics. Significance Statement: Classic frameworks of vision attribute perception of inherent object characteristics, such as size, to the ventral visual pathway, and processing of spatial characteristics relevant to action, such as distance, to the dorsal visual pathway. However, these frameworks are based on studies that used projected images of objects whose actual size and distance from the observer were ambiguous. Here, we find that when object size and distance information in the stimulus is less ambiguous, these characteristics are widely represented in both visual pathways. Our results provide valuable new insights into the brain representations of objects and their various physical attributes in the context of naturalistic vision.

Human memory for real-world solid objects is not predicted by responses to image displays.

In experimental psychology and neuroscience, computerized image stimuli are typically used as artificial proxies for real-world objects to understand brain and behavior. Here, in a series of five experiments (n = 165), we studied human memory for objects presented as tangible solids versus computerized images. We found that recall for solids was superior to images, both immediately after learning, and after a 24-hr delay. A "realness advantage" was also evident relative to three-dimensional (3-D) stereoscopic images, and when solids were viewed monocularly, arguing against explanations based on the presence of binocular depth cues in the stimulus. Critically, memory for solids was modulated by physical distance, with superior recall for objects positioned within versus outside of observers' reach, whereas recall for images was unaffected by distance. We conclude that solids are processed quantitatively and qualitatively differently in episodic memory than are images, suggesting caution in assuming that artifice can always substitute for reality. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

CRISPR-Cas9-mediated knockout of CYP79D1 and CYP79D2 in cassava attenuates toxic cyanogen production.

Cassava (Manihot esculenta) is a starchy root crop that supports over a billion people in tropical and subtropical regions of the world. This staple, however, produces the neurotoxin cyanide and requires processing for safe consumption. Excessive consumption of insufficiently processed cassava, in combination with protein-poor diets, can have neurodegenerative impacts. This problem is further exacerbated by drought conditions which increase this toxin in the plant. To reduce cyanide levels in cassava, we used CRISPR-mediated mutagenesis to disrupt the cytochrome P450 genes CYP79D1 and CYP79D2 whose protein products catalyze the first step in cyanogenic glucoside biosynthesis. Knockout of both genes eliminated cyanide in leaves and storage roots of cassava accession 60444; the West African, farmer-preferred cultivar TME 419; and the improved variety TMS 91/02324. Although knockout of CYP79D2 alone resulted in significant reduction of cyanide, mutagenesis of CYP79D1 did not, indicating these paralogs have diverged in their function. The congruence of results across accessions indicates that our approach could readily be extended to other preferred or improved cultivars. This work demonstrates cassava genome editing for enhanced food safety and reduced processing burden, against the backdrop of a changing climate.

Action properties of object images facilitate visual search.

There is mounting evidence that constraints from action can influence the early stages of object selection, even in the absence of any explicit preparation for action. Here, we examined whether action properties of images can influence visual search, and whether such effects were modulated by hand preference. Observers searched for an oddball target among 3 distractors. The search arrays consisted either of images of graspable "handles" ("action-related" stimuli), or images that were otherwise identical to the handles but in which the semicircular fulcrum element was reoriented so that the stimuli no longer looked like graspable objects ("non-action-related" stimuli). In Experiment 1, right-handed observers, who have been shown previously to prefer to use the right hand over the left for manual tasks, were faster to detect targets in action-related versus non-action-related arrays, and showed a response time (reaction time [RT]) advantage for rightward- versus leftward-oriented action-related handles. In Experiment 2, left-handed observers, who have been shown to use the left and right hands relatively equally in manual tasks, were also faster to detect targets in the action-related versus non-action-related arrays, but RTs were equally fast for rightward- and leftward-oriented handle targets. Together, or results suggest that action properties in images, and constraints for action imposed by preferences for manual interaction with objects, can influence attentional selection in the context of visual search. (PsycINFO Database Record

Inhibition of bladder tumor growth by the green tea derivative epigallocatechin-3-gallate.

PURPOSE: We evaluated the green tea derivative epigallocatechin-3-gallate (EGCG) as an intravesical agent for the prevention of transitional cell tumor implantation. MATERIALS AND METHODS: In vitro studies were performed in the AY-27 rat transitional cell cancer and the L1210 mouse leukemia cell lines. Cells were exposed to increasing concentrations of EGCG for 30 minutes to 48 hours. Surviving cell colonies were then determined. A DNA ladder assay was performed in the 2 cell lines. Fisher 344 rats were used for in vivo studies with an intravesical tumor implantation model. Group 1 (12 rats) served as a control (tumor implantation and medium wash only). In group 2 (28 rats) 200 microM EGCG were instilled intravesically 30 minutes after tumor implantation. Rats were sacrificed 3 weeks following treatment. Gross and histological analyses were then performed on the bladders. RESULTS: At 6.0 x 104 cells per 100 mm dish a time dose dependent response was observed. After 2 hours of treatment with EGCG 100% cell lethality of the AY-27 cell line occurred at concentrations greater than 100 microM. Strong banding on the DNA ladder assay was seen with the L1210 mouse leukemia cell line. Only weak banding patterns were found in the AY-27 cell line treated with EGCG (100 and 200 microM) for 24 hours. All 12 controls were successfully implanted with tumors. In group 2 (EGCG instillation) 18 of the 28 animals (64%) were free of tumor (Fisher's exact test p = 0.001). CONCLUSIONS: The clonal assays showed a time dose related response to EGCG. Intravesical instillation of EGCG inhibits the growth of AY-27 rat transitional cells implanted in this model.