Vision research at Rochester is organized into three major themes:
- The neural mechanisms that underlie visual experience,
- the role of vision in guiding behavior,
- and advanced technologies of ophthalmic optics.
Most faculty in CVS contribute to two or more of these themes.
CVS had been built on the conviction that progress in vision science requires the coordinated efforts of scientists with very different skills. Researchers in the center apply a number of approaches to their research; many apply more than one. Core methodological foci are:
- advanced neuroscience methods
- behavioral and psychophysical methods
- computational analysis and modeling
- advanced optical techniques
Researchers in CVS have been at the forefront in developing advanced scientific techniques, including multi-electrode recordings in awake-behaving monkeys, virtual reality tools for studying complex visuomotor behaviors, advanced mathematical analysis of behavioral and neural data, and the application of adaptive optics to basic and clinical vision research.
Richard Aslin : Perceptual learning and development
Aslin is interested in the processes and mechanisms that lead to the development of sensory, perceptual, and cognitive abilities in human infants. A line of work that grew out of studies of auditory sequence learning has investigated how adults, children, and infants group sequentially presented elements based solely on the distributional cues (conditional probabilities) contained in the stream of elements. Element-sequences have consisted of simple 2-D shapes, as well as spatially defined locations in a serial reaction time task.
His most recent work has extended this rapid statistical learning from the temporal to the spatial domain by presenting elements simultaneously, thereby creating configurations defined by their spatial correlation. Both adults and human infants are remarkably sensitive to these spatial correlations in multi-element scenes, and on-going work is using eye-tracking to reveal the attentional constraints on statistical learning. Students are trained in the use of psychophysical methods adapted to assess perceptual performance in infants and young children.
Daphne Bavelier : Plasticity, vision, fMRI
A distinctive feature of the human brain is its capacity to learn and adapt to an ever-changing environment. What are the factors that promote such learning and brain plasticity? Are some parts of our nervous system more plastic than others, making some skills easier to acquire? Answers to these questions are central to basic science, education, clinical rehabilitation, and aging.
To address these questions, my laboratory uses a multidisciplinary approach (behavior, brain imaging, eye tracking) to study how individuals learn and adapt to changes in experience, whether induced by nature (deafness) or training (playing video games). Our work and that of others in the field highlights that, although possible, brain plasticity is highly specific. Overcoming this specificity would be advantageous.
Mina Chung : Inherited retinal diseases and genetic factors contributing to age-related macular degeneration
Dr. Chung's research interests include inherited retinal diseases and genetic factors contributing to age-related macular degeneration. Dr. Chung has an adjunct faculty appointment as a member of the University of Rochester Center for Visual Sciences and participates in teaching a graduate-level course in the Department of Optics.
In collaboration with CVS, she is developing new adaptive optics technology for retinal imaging to study early cellular changes in macular diseases. She was awarded a research grant from the Howard Hughes Medical Institute to study patients with macular diseases using adaptive optics imaging technology and multifocal electroretinography, a clinical test of the retinal photoreceptors.
Greg DeAngelis : Neural basis of 3D visual perception and multi-sensory cue integration
The main goal of work in the DeAngelis lab is to understand the neural basis of visual perception and visually-guided behavior. A major challenge is to understand how the brain computes the location and movement of objects in three-dimensional space, and how these computations take into account motion of the observer. The approach is to link neuronal activity to perception as closely as possible using a combination of electrophysiology and psychophysics in alert trained monkeys.
Major emphasis is placed on establishing causal links between neural activity and behavior using techniques such as electrical microstimulation and reversible inactivation. Current research in the DeAngelis lab has 3 main foci:
- neural mechanisms of depth perception from binocular disparity and motion parallax;
- neural substrates of multisensory (visual/vestibular) integration for self-motion perception; and
- neural mechanism of optimal (i.e., Bayesian) cue integration.
Students in the lab are trained in quantitative electrophysiology and psychophysics, statistical analysis of neural and behavioral data, and computational modeling of neural population codes.
Charles Duffy : Neural processing of motion, spatial orientation
Duffy studies the activity of extrastriate visual areas, using single unit recordings in awake macaques and psychophysical methods in humans and macaques to examine mechanisms of spatial orientation. Past work has demonstrated the existence of neurons that are specifically activated during the viewing of optic flow fields and other complex motions, and this work has shown that the viewing of optic flow produces illusions that provide powerful insights into the neural mechanism involved. Future experiments will use feedback controlled full field visual stimulators and sled induced vestibular stimulation to study mechanisms of spatial orientation in healthy monkeys and humans and diseased humans. Students are trained in single unit recording in awake monkeys performing visual tasks, and in the analysis of simultaneous visual and vestibular stimulation.
Steven Feldon : Orbital disease and neuro-ophthalmology
Dr. Feldon's research interests involve using his expertise in thyroid eye disease to investigate the role of fibroblasts in Graves' disease. In a collaborative effort with Dr. Richard Phipps, the aim is to develop a model of how immune system cells interact with orbital fibroblasts. The hope is to develop rational therapy treatments for this and possibly other autoimmune diseases affecting eye structures. Dr. Feldon's work also involves national clinical trails in the management of idiopathic intracranial hypertension; radiation treatment for Graves' ophthalmology; and quantification of visual field defects and analysis of optic disc photographs in Ischemic optic neuropathy. In addition he is an inventor of devices for ophthalmology including tonometers and holds seven patents.
Jim Fienup : Image processing, wavefront sensing
Professor Fienup's research interests center around imaging science. His work includes unconventional imaging, phase retrieval, wavefront sensing, and image reconstruction and restoration. These techniques are applied to passive and active optical imaging systems, synthetic-aperture radar, and biomedical imaging modalities. His past work has also included diffractive optics and image quality assessment.
Edward Freedman : Neural control of coordinated movements
In order to interact with objects in our environment we must be able to gather accurate sensory information about our surroundings, distinguish our movements from the movements of objects in the world, and coordinate our own movements in order to orient, and navigate smoothly through a complex environment. In my lab we study the neural control of coordinated orienting behaviors including gaze shifts and pursuit of stationary and moving targets in the head-unrestrained subject. We seek to understand the roles of neurons in the brainstem, cerebellum and cortex in generating and executing these movements within the context of testing critical predictions of models (i.e. hypotheses) of these critical sensorimotor control systems.
Lin Gan : Development of mammalian retina and inner ear
Human retina and inner ear are the most common places of genetic disorders that cause blindness and deafness due to the degeneration of retinal and inner ear neurons. To understand the disease processes, the research in our Laboratory focuses on elucidating the molecular mechanisms regulating the normal development and maintenance of these neurons. We have been investigating the roles of three classes of transcription factors (TFs), the basic helix-loop-helix (bHLH), POU-homeodomain (POU-HD), and LIM-domain TFs, in mouse retina and inner ear. Using homologous recombination in mouse embryonic stem (ES) cells to mutate these TF genes, we have shown that these TFs function in a genetic cascade to regulate the differentiation of neuronal progenitor cells into specific types of neurons and to regulate the maturation and survival of post-differentiation neurons. We intend to explore the application of these factors in neuronal protection and in the regeneration of specific retinal and inner ear neurons from stem cells.
Benjamin Hayden : Neural basis of decision-making
We are constantly confronted with choices: What should we eat? How should we allocate our time? Where should we go next? Should we follow a safe path or a risky one that offers a potentially larger payoff? The brain has evolved sophisticated machinery to balance competing interests to make beneficial choices. Our lab wants to know how the brain solves these problems - and why it fails so often. Specifically, we are interested in identifying the neural calculations that promote adaptive decision-making, especially when rewards are involved. To do this, our lab records the activity of single neurons during simple eye movement choices. To eye movement system is particularly appealing because the underlying control circuitry is well-understood.
Holly Hindman : Corneal wound healing, ocular optics, and keratoplasty procedures
Dr. Hindman is a clinician-scientist whose clinical expertise is in the treatment of cornea and ocular surface disease and in their surgical management with various types of corneal transplantation procedures. Dr. Hindman's research interest is in exploring the reason for post-operative limitations in visual function following these procedures. In collaboration with Dr. Krystel Huxlin, Dr. Geunyoung Yoon, and Dr. Richard Phipps, she is identifying the role of keratocyte activation into scar-forming myofibroblasts on post-operative ocular optics and on visual performance. Her lab uses a three-pronged approach to investigate their hypotheses – cell biology studies of corneal wound healing, prospective clinical studies, and prospective experimental studies.
Jennifer Hunter : Mechanisms of light-induced retinal damage, Development of non-invasive fluorescence imaging techniques
Dr. Hunter's research interests include mechanisms of light-induced retinal damage and development of non-invasive fluorescence imaging techniques to study retinal function in healthy and diseased eyes.
Krystel Huxlin : Improving vision after damageperceptual learning and physiological optics
Our first research avenue examines the neuronal changes that are key to the recovery of visual functions after brain damage in adulthood. We use psychophysical techniques to measure and retrain visual performance in adult cats following damage to the visual cortex. Anatomical and histological studies in the same animals allow us to correlate neuronal changes with the degree and type of visual recovery. More recently, we have started to use this knowledge to develop therapeutic strategies that promote visual recovery following brain damage in adult humans.
Our second avenue of research is intended to provide new insights into the biological causes of increased optical aberrations in the eye following laser refractive surgery. Our laboratory has developed a fixating cat animal model in which we can reliably correlate optical aberrations, corneal structure and biology. Such complex correlation is essential if we are to gain the knowledge to design laser ablation algorithms and post-operative treatments that prevent or correct optical aberrations and improve long-term visual outcomes in humans.
Robert Jacobs : Perceptual learning; visual psychophysics; computational modeling
Jacobs studies perceptual learning using experimental and computational methodologies. Perceptual environments are highly redundant. People obtain information from many sensory modalities, including vision, audition, and touch. Individual modalities also contain multiple information sources. Visual environments, for instance, give rise to many visual cues, including motion, texture, and shading. Jacobs is interested in how people take advantage of sensory redundancy for the purposes of perceptual learning. For example, a person might (unconsciously) notice that two visual cues provide consistent information about the shape of an object whereas a third cue indicates a different shape. If so, then the person might conclude that the first two cues are reliable information sources, but that the third cue is less reliable. The person can then adapt his or her sensory integration rule accordingly. The lab often compares human performances with the performances of Ideal Observers which are computational models based on Bayesian statistics that make perceptual judgments in a statistically optimal manner. Jacobs is interested in using techniques from the machine learning and statistics literatures to develop new ways of defining Ideal Observers for interesting perceptual tasks. Once an Ideal Observer is defined, it can be used to evaluate whether people perform a task optimally. If so, then we can conclude that people are using all the relevant information in an efficient manner. If not, then we can examine why they are sub-optimal and what can be done to improve their performances.
David Knill : Visual perception, visual psychophysics, computational vision, visuomotor control
Knill's research focuses on two problems: the structure of the visual computations that underlay 3D perception in humans and how the brain uses visual information to control motor behavior. The work on perceptual processing uses computational analyses of visual information (e.g. the degree of uncertainty and the nature of the ambiguities associated with a cue) to motivate psychophysical experiments on how humans use the information for perception. Knill has, for example, made novel use of the ideal observer paradigm to elucidate the features within texture patterns that provide the most salient information to human observers. For the work on visuomotor control, the lab contains a virtual display system with a real-time motion tracking system. Researchers in the lab study the structure of the visual computations underlying motor control by measuring the effects of perturbations in the visual information provided to subjects during a reach on the kinematics of the reach. Students in the lab learn the computer skills needed to do 3D psychophysics and the modeling tools used to generate theoretical predictions and analyze behavioral data; particularly, geometric and statistical modeling methods.
Wayne Knox : Femtosecond laser technology for vision
The Knox group is working on new approaches to vision correction including femtosecond micromachining in ophthalmic polymers such as hydrogels and hydrophobic acrylates. They have written various diffractive and refractive structures as well as waveguides into ophthalmic materials with index changes as high as +0.10. The studies may result in new approaches to vision correction involving IOL surgery and other applications. In collaboration with Dr. Huxlin, Knox has carried out studies of refractive index modifications using femtosecond micromachining in live corneal tissue without tissue destruction and cell death. Another area of research involves use of high resolution nonlinear imaging techniques to study diffusion of dopants in the live cornea, and these have potential applications in corneal drug delivery.
Peter Lennie : Functional organization of visual pathways; Mechanisms of color vision
My work sits at the interface between visual perception and visual physiology. All my research is connected by the idea that visual perception can be explained in terms of underlying neural mechanisms. The work involves both perceptual experiments to explore performance, and physiological ones to record the activity of single neurons, the aim being, where possible, to link observations in the two domains. My recent work has focused on two broad problems: how the visual selectivities of neurons become elaborated at successive levels in the visual pathway, and how signals about color are represented in the brain.
Richard Libby : Neurobiology of Glaucoma
Glaucoma is a complex group of diseases where many different genetic and environmental factors conspire to cause vision loss. While there are many different causes of glaucoma, the ultimate cause of vision loss in all glaucomas is the death of retinal ganglion cells (RGCs), the output neurons of the retina. Therefore, glaucoma is a neurodegeneration. Our lab focuses on the neurobiology of glaucoma. Primarily, we use mouse models of glaucoma and advanced mouse genetics to probe the pathophysiology of glaucoma. Specifically, we are interested in understanding the molecular processes that lead to RGC death in glaucoma and why are RGCs more likely to die in some patients than in others.
Scott MacRae : Refractive surgery
Dr. MacRae's main research is in using wavefront measurements to correct vision beyond the 20/20 level and improve contrast. He works closely with Drs. David Williams and Geunyoung Yoon, as well as industry. While some of his research studies are designed to obtain FDA approval for laser vision correction devices as well as presbyopic intraocular lenses for cataract surgery. His Studies of "customized LASIK" developed the Rochester Advanced Nomogram used by LASIK surgeons around the world. He is also working on improving optics of intraocular lenses that allow patients to see at distance and near after cataract surgery. Based at the state-of-the-art StrongVision clinic, Dr. MacRae combines a specialty refractive surgical practice with his research activities. He has over 25 years experience as a corneal specialist, cataract and LASIK surgeon.
Brad Mahon : The representation of concepts and categories
I study the cognitive and neural processes that make possible very simple things that we do on a daily basis. Imagine there is a glass of water on the table. One may look at the glass and name it as 'a glass of water'; or, one may simply pick up the glass and take a drink. My research addresses the processes involved in categorization and recognition of the visual input, the engagement of motor knowledge necessary to manipulate objects, and the dynamics of information retrieval within the speech production system. The goal of this research program is to merge insights from studies of neuropsychological patients with functional imaging studies of the healthy brain in order to articulate a model of object use and object naming.
Ania Majewska : Imaging synaptic structure and function in the visual system
Our research interests lie in understanding how visual activity shapes the structure and function of connections between neurons in the visual cortex. During the critical period, closure of one eye leads to a shift in the responses of neurons towards the open eye. My lab's current work focuses on the structural basis for this rapid ocular dominance plasticity using in vivo two-photon microscopy to elucidate single cell structure deep in the intact brain. Our experiments suggest that fine scale changes in synaptic connectivity underlie rapid ocular dominance plasticity without an overall remodeling of the pre and postsynaptic scaffold. My lab is also interested in the mechanisms which underlie structural remodeling at synapses. Imaging, electrophysiology and immunohistochemistry carried out in brain slices allows us to explore the contributions of different pathways to structural plasticity. Our work has shown that both intracellular pathways and the extracellular matrix are involved in synapse remodeling during synaptic plasticity.
Walter Makous : Visual processes
Current research lies primarily in two disparate areas: (1) collaborations with others (e. g., David Williams and Daphne Bavelier) on visual processes, and (2) investigation into the relationship between science and the Judeo-Christian Bible. (No longer an active research participant at Rochester.)
William Merigan : Function of primate extrastriate cortical areas
Merigan's research asks how the complex perceptual abilities of primates are mediated by the neural processing that takes place in the ventral stream of extrastriate visual cortex. He studies texture segmentation, shape recognition, perceptual grouping, visual search and motion perception in macaques and humans, and relates these abilities to the function of particular cortical areas. His recent research has focused on areas V4, TEO and TE in macaques and related areas in humans. Students learn to use localized inactivation, single unit physiology, and perceptual testing to examine the role of these areas in vision.
Gary Paige : Multisensory interaction and adaptive plasticity in spatial localization and orientation
The integration of sensory-neural processes underlying our abilities to localize, track, and interact with a cluttered environment are fundamental attributes of daily life, ranging from mundane tasks such as reaching for objects to complex ones such as navigating to and from the workplace. These functions are also among the first to register problems with disease and aging. The goal of our research is to understand how the brain integrates sensory inputs from the outside world (location and motion of visual and auditory targets) with those of the internal senses (vestibular and somatosensory) to achieve meaningful spatial perceptions and behaviors, particularly eye, head and postural movements. An equally important interest is how plastic neural mechanisms register errors and adaptively adjust performance in order to maintain proper spatial calibration across modalities. Finally, an important translational concern is how natural aging affects both spatial behavior and adaptive plasticity. Our research environment is unique in structure and instrumentation, as well as broad and translational in character. We benefit from a collegiate and multi-disciplinary group of faculty and students working on problems of common interest.
Tatiana Pasternak : Processing and storage of visual information
My current research is focused on the mechanisms underlying processing and storage of visual motion information in primate cortex. In our studies we combine single cell recordings, microstimulation, reversible inactivation with psychophysical measures of visual performance. We have shown that neurons in visual cortical area MT, strongly associated with processing of visual motion, also participate in the storage and the retrieval/comparison operations required by working memory tasks. Recordings from prefrontal cortex, a likely source of cognitive signals, during the performance of the same memory tasks revealed prevalence of motion selective signals that were strongly modulated by task demands. These signals most likely originated in area MT and their nature suggests that prefrontal neurons have access to the basic mechanisms underlying motion selectivity of MT neurons. We also found that neuronal activity of both areas recorded during different stages of the task is predictive of the monkey's decision. This work suggests that prefrontal cortex together with area MT actively participate in the performance of working memory for motion tasks. Our current efforts are focused on elucidating the nature of dynamic interactions between these two areas as well as on identifying other components of the circuitry underlying the ability to discriminate and store visual motion signals.
Alexandre Pouget : Neural computation and spatial perception
Pouget's research focuses on two main topics: neural coding and spatial representations. The goal of the work on neural coding is to understand how neurons encode information, such as the color of an object or the direction of the next hand movement, and how computation is carried out in the cortical circuits. Pouget is particularly interested in population coding, a widespread coding scheme in the brain, in which variables are encoded through the concerted activity of large sets of neurons. His research on spatial representations explores how the brain represents the position of objects and how these representations are used to control spatial behaviors such as reaching or navigation. Pouget has developed a novel theoretical framework, based on the theory of basis functions, which accounts for the response of single cells in the parietal cortex and which explains the behavior of human patients suffering from hemineglect --- a severe impairment of spatial perception. Students in Pouget's lab learn behavioral techniques, including eye, head and hand tracking, for studying spatial behaviors and computational techniques for developing and analyzing physiologically plausible models of neural function.
Jannick Rolland : Optical system design and instrumentation for illumination optics, imaging science, and 3D visualization
Rolland's research interests center around optical system design and instrumentation for illumination optics, imaging science, and 3D visualization. Her current developments include state-of-the-art optical coherence tomography (OCT) systems, illumination devices, and head-worn displays (HWDs/HMDs). The research is expanding to leverage the emerging technology of freeform-optics. OCT is applied to tear-film measurements and keratoconus imaging; Illumination is applied to photodynamic therapy; HWDs may be used to support the investigation of brain functions. Recent works also included advances in image quality assessment as well as the development of a wavefront curvature sensor and associated wavefront reconstruction. She has over 90 peer reviewed publications and 18 patents.
Lizabeth Romanski : Functional organization of the primate frontal lobes
The integration of auditory and visual stimuli is crucial for recognizing objects by sight and sound, communicating effectively, and navigating through our complex world. While auditory and visual information are combined in many sites of the human brain, the combining of face and vocal information for effective communication has been shown to occur in specialized regions of the temporal and frontal lobes. Work in my laboratory is focused on how the ventral prefrontal cortex represents high level auditory information and the neuronal mechanisms which underlie integration of complex auditory and visual information, primarily face and vocal information during communication. Studies in our laboratory have shown that neurons within specific regions of the ventral prefrontal cortex are robustly responsive to complex sounds including species-specific vocalizations, while previous studies have shown that adjacent ventral prefrontal regions are selectively responsive to faces. We have shown that neurons within ventral prefrontal cortex are multisensory and respond to both faces and to the corresponding vocalizations. We are also interested in the factors that affect the integration of dynamic faces and vocalizations in the frontal lobe including temporal coincidence, stimulus congruence, as well as the emotional expression conveyed in the face-vocalization and the identity of the speaker. Further analysis of the neural mechanisms which support face and voice integration in non-human primates may help us to understand the mechanisms underlying social communication and social cognition.
Marc H. Schieber : Sensorimotor control of finger movements
Schieber's lab investigates how the nervous system controls visually-guided finger movements, like those people use in performing delicate surgery. One line of investigation focuses on how the primary motor cortex controls visually-cued finger movements. A second line of work investigates how the premotor cortex and striatum choose among multiple visual targets for potential motoric interaction. Students in Schieber's lab learn physiological and behavioral techniques for studying visuomotor control in primates and humans.
Duje Tadin : Neural mechanisms of visual perception
Tadin uses psychophysics, transcranial magnetic stimulation (TMS), fMRI, and eye-tracking to investigate neural mechanisms of visual perception in normal and special populations. Current topics include motion perception, binocular rivalry, visual awareness, contextual interactions, perceptual learning, visual adaptation, attention and temporal dynamics of vision. Tadin's psychophysical work has revealed several counterintuitive characteristics of human motion perception and linked these findings with cortical center-surround mechanisms. Follow-up work investigated temporal and spatial properties of center-surround interactions across visual sub-modalities in normal, schizophrenic and MDMA-user populations. Another line of Tadin's research uses binocular rivalry and visual crowding as experimental methods for studying the characteristics of visual awareness. Combined use of rigorous psychophysical methods and TMS allows Tadin to make causal inferences about the neural mechanisms of visual perception. These lines of research are supplemented with related investigations of visual processing in special populations, including schizophrenic patients, low-vision children and chronic drug users.
David R. Williams : Limits of human vision
Williams uses psychophysical, anatomical, and imaging techniques to understand how the structure of the eye and brain affects visual performance. He has used laser interferometric methods to psychophysically measure the spacing and diameter of photoreceptors in the living human eye. Another project uses adaptive optics to obtain an improved measure of the optical quality of the eye. His laboratory has recently acquired images of the living human retina that resolve single cone photoreceptors for the first time. A related project has provided the first differential absorption images of the primate photoreceptor mosaic that can distinguish the three cone types responsible for human color vision. Students learn a wide range of methods including the design and analysis of optical systems, visual psychophysics, retinal imaging, image processing, and the mathematical analysis of spatial and temporal sampling.
Geunyoung Yoon : Supernormal vision
It has been known that the human eye suffers from higher order monochromatic aberrations as well as defocus and astigmatism. The development of technology to correct the eye's higher order aberrations raises the issue of how much vision improvement can be obtained. An adaptive optics (AO) system that measures and corrects the eye's aberrations provides supernormal vision and improves both the contrast sensitivity and visual acuity by correcting the higher order aberration over conventional correction methods. These results encourage the development of customized correction methods such as laser refractive surgery, contact lenses, and IOLs to achieve supernormal vision in everyday life. However, it is true that several factors such as photoreceptor sampling, biomechanical response of the cornea, and chromatic aberration reduce the benefit of supernormal vision that could be provided by customized correction methods.