Faculty Bibliography

The objective analysis of eye movements has a significant history and has been long proven to be an important research tool in the setting of brain injury. Quantitative recordings have a strong capacity to screen diagnostically. Concurrent examinations of the eye and upper limb movements directed toward shared functional goals (e.g., eye-hand coordination) serve as an additional robust biomarker-laden path to capture and interrogate neural injury, including acquired brain injury (ABI). While quantitative dual-effector recordings in 3-D afford ample opportunities within ocular-manual motor investigations in the setting of ABI, the feasibility of such dual recordings for both eye and hand is challenging in pathological settings, particularly when approached with research-grade rigor. Here we describe the integration of an eye tracking system with a motion tracking system intended primarily for limb control research to study a natural behavior. The protocol enables the investigation of unrestricted, three-dimensional (3D) eye-hand coordination tasks. More specifically, we review a method to assess eye-hand coordination in visually guided saccade-to-reach tasks in subjects with chronic middle cerebral artery (MCA) stroke and compare them to healthy controls. Special attention is paid to the specific eye- and limb-tracking system properties in order to obtain high fidelity data from participants post-injury. Sampling rate, accuracy, permissible head movement range given anticipated tolerance and the feasibility of use were several of the critical properties considered when selecting an eye tracker and an approach. The limb tracker was selected based on a similar rubric but included the need for 3-D recording, dynamic interaction and a miniaturized physical footprint. The quantitative data provided by this method and the overall approach when executed correctly has tremendous potential to further refine our mechanistic understanding of eye-hand control and help inform feasible diagnostic and pragmatic interventions within the neurological and rehabilitative practice.

BACKGROUND:Concussion leads to neurophysiologic changes that may result in visual symptoms and changes in ocular motor function. Vision-based testing is used increasingly to improve detection and assess head injury. This review will focus on the historical aspects and emerging data for vision tests, emphasizing rapid automatized naming (RAN) tasks and objective recording techniques, including video-oculography (VOG), as applied to the evaluation of mild traumatic brain injury. METHODS:Searches on PubMed were performed using combinations of the following key words: "concussion," "mild traumatic brain injury," "rapid automatized naming," "King-Devick," "mobile universal lexicon evaluation system," "video-oculography," and "eye-tracking." Additional information was referenced from web sites of vendors of commercial eye-tracking systems and services. RESULTS:Tests of rapid number, picture, or symbol naming, termed RAN tasks, have been used in neuropsychological studies since the early 20th century. The visual system contains widely distributed networks that are readily assessed by a variety of functionally distinct RAN tasks. The King-Devick test, a rapid number naming assessment, and several picture-naming tests, such as the Mobile Universal Lexicon Evaluation System (MULES) and the modified Snodgrass and Vanderwart image set, show capacity to identify athletes with concussion. VOG has gained widespread use in eye- and gaze-tracking studies of head trauma from which objective data have shown increased saccadic latencies, saccadic dysmetria, errors in predictive target tracking, and changes in vergence in concussed subjects. Performance impairments on RAN tasks and on tasks recorded with VOG are likely related to ocular motor dysfunction and to changes in cognition, specifically to attention, memory, and executive functioning. As research studies on ocular motor function after concussion have expanded, so too have commercialized eye-tracking systems and assessments. However, these commercial services are still investigational and all vision-based markers of concussion require further validation. CONCLUSIONS:RAN tasks and VOG assessments provide objective measures of ocular motor function. Changes in ocular motor performance after concussion reflect generalized neurophysiologic changes affecting a variety of cognitive processes. Although these tests are increasingly used in head injury assessments, further study is needed to validate them as adjunctive diagnostic aids and assessments of recovery.

Though abnormalities of visuospatial function occur in Parkinson's disease, the impact of such deficits on functional independence and psychological wellbeing has been historically under- recognized, and effective treatments for this impairment are unknown. These symptoms can be encountered at any stage of the disease, affecting many activities of daily living, and negatively influencing mood, self-efficacy, independence, and overall quality of life. Furthermore, visuospatial dysfunction has been recently linked to gait impairment and falls, symptoms that are known to be poor prognostic factors. Here, we aim to present an original modality of neurorehabilitation designed to address visuospatial dysfunction and related symptoms in Parkinson's disease, known as "Art Therapy". Art creation relies on sophisticated neurologic mechanisms including shape recognition, motion perception, sensory-motor integration, abstraction, and eye-hand coordination. Furthermore, art therapy may enable subjects with disability to understand their emotions and express them through artistic creation and creative thinking, thus promoting self-awareness, relaxation, confidence and self-efficacy. The potential impact of this intervention on visuospatial dysfunction will be assessed by means of combined clinical, behavioral, gait kinematic, neuroimaging and eye tracking analyses. Potential favorable outcomes may drive further trials validating this novel paradigm of neurorehabilitation.