Search for: All records

Almost 400 years ago, Rubens copied Titian's The Fall of Man, albeit with important changes. Rubens altered Titian's original composition in numerous ways, including by changing the gaze directions of the depicted characters and adding a striking red parrot to the painting. Here, we quantify the impact of Rubens's choices on the viewer's gaze behavior. We displayed digital copies of Rubens's and Titian's artworks—as well as a version of Rubens's painting with the parrot digitally removed—on a computer screen while recording the eye movements produced by observers during free visual exploration of each image. To assess the effects of Rubens's changes to Titian's composition, we directly compared multiple gaze parameters across the different images. We found that participants gazed at Eve's face more frequently in Rubens's painting than in Titian's. In addition, gaze positions were more tightly focused for the former than for the latter, consistent with different allocations of viewer interest. We also investigated how gaze fixation on Eve's face affected the perceptual visibility of the parrot in Rubens's composition and how the parrot's presence versus its absence impacted gaze dynamics. Taken together, our results demonstrate that Rubens's critical deviations from Titian's painting have powerful effects on viewers’ oculomotor behavior. 

Abstract Troxler fading, the perceptual disappearance of stationary images upon sustained fixation, is common for objects with equivalent luminance to that of the background. Previous work showed that variations in microsaccadic rates underlie the perceptual vanishing and intensification of simple stimuli, such as Gabor patches. Here, we demonstrate that microsaccade dynamics also contribute to Troxler fading and intensification during the viewing of representational art. Participants fixated a small spot while viewing either a Gabor patch on a blank background, or Monet’s painting “Impression, Sunrise.” They continuously reported, via button press/release, whether the Gabor patch, or the sun in Monet’s painting, was fading versus intensifying, while their eye movements were recorded with high precision. Microsaccade rates peaked before reports of increased visibility, and dropped before reports of decreased visibility or fading, both when viewing Gabor patches and Monet’s sun. These results reveal that the relationship between microsaccade production and the reversal and prevention of Troxler fading applies not only to the viewing of contrived stimuli, but also to the observation of “Impression, Sunrise.” Whether or not perceptual fading was consciously intended by Monet, our findings indicate that observers’ oculomotor dynamics are a contributor to the cornerstone of Impressionism. 

Several problems challenge mesoscopic imaging in the brain: 1) Difficulty with positioning high-NA objectives near the brain; 2) Creating a flat imaging window against the surface of the brain; 3) Adjusting the imaging window in the face of changes in swelling and pressure in the brain; 4) Preventing growth of dura and biofilms that obscure the imaging window; 5) Follow-on MRI imaging of the animal post-implantation. We propose here an ultra-large window radiolucent implant to address these issues. Our approach provides a 2 cm diameter window for non-human primates (NHPs) that regulates pressure and employs a stable, strong, and thin design. The system is mechanically modeled and stress-tested to achieve access to the brain by large objectives, with design features that allow for manual repositioning of the imaging lens. To optimize the distance between the objective and the brain, we prioritize a thin implant design. A strong radiolucent implant is created using PEEK plastic, a strong, thermoresistant and biostable material. We heighten strength of the chamber’s attachment to the skull by using titanium screws that are normal to the surface of the bone at each point. The implant design has several parts and contemplates a potential method to maintain pressure on the brain. This method uses an engineered silicone mount to maintain even pressure of the imaging window on the brain’s surface, despite brain motion. The mechanical properties of the silicone are manipulated to closely resemble that of brain tissue to be more biomimetic and act as a cushion for motion. This method also allows for themanual repositioning of the cover slip to create a flat imaging window. Lastly, our approach prevents dural growth by blocking the migration of migratory biofilm-forming cells; we hypothesize that use of dynamic pressure maintenance on the brain is key to this method’s success. We are also investigating methods to elongate the longevity of the implant and imaging site, such as silver sputtering on implants and blue light therapy. These methods have produced an ultra-large field of view with 2P image results in <60,000 neurons. As such the chambers are expected to enhance recording window longevity and may prove to be a critical advance in NHP and human brain imaging. 

Troxler fading is described as the perceptual disappearance of stationary images, often in the visual periphery, during sustained fixation. Microsaccades have been shown to counteract and reverse the perceptual fading of contrived stimuli such as Gabor patches (Costela, McCamy, Macknik, Otero‐Millan, & Martinez-Conde, 2013; McCamy, Macknik, & Martinez‐Conde, 2014; McCamy et al., 2012). Here we demonstrate that microsaccadic dynamics similarly drive equivalent perceptual alternations in representational art. This approach can help deepen our understanding of masterpieces such as Claude Monet's “Impression, Sunrise” (“Impression, soleil levant”), in which a red sun rises over two small fishing boats in a port. Though the red sun appears perceptually brighter than the surrounding sky, Livingstone (2002) showed that the sun and the surrounding sky have the same approximate luminance. Equiluminance between an object and its background is known to facilitate Troxler fading. Accordingly, Safran & Landis (1998) noticed that staring at the sailor in Monet’s painting results in perceptual fading of the sun. We set out to assess whether the perceptual fading of the sun in “Impression, Sunrise” depends on microsaccade production. If so, it would indicate that the vanishing of the sun in Monet’s masterpiece represents an instantiation of Troxler fading in art.