Efficiently Recording the Eye-Hand Coordination to Incoordination Spectrum

Summary

Cerebral injury can damage both ocular and somatic motor systems. Characterization of motor control post-injury affords biomarkers that assist in disease detection, monitoring, and prognosis. We review a method to measure eye-hand movement control in health and in pathologic incoordination, with look-and-reach paradigms to assess coordination between eye and hand.

Abstract

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. 

Introduction

A critical element of the neurological function is eye-hand coordination or the integration of ocular and manual motor systems for the planning and execution of combined function towards a shared goal, for example, a look, reach and grab of the television remote. Many purposeful tasks depend on visually guided actions, such as reaching, grasping, object manipulation and tool use, which hinge on the temporally and spatially coupled eye and hand movements. Acquired brain injuries (ABI) cause not only limb dysfunction but also ocular dysfunction; more recently, there is also evidence pointing to the dysfunction of eye-hand coordination¹. Coordinat....

Protocol

1. Participant

1. Recruit control participants older than 18 years, without a history of neurological dysfunction, significant eye injury, significant depression, major disability and/or electrical implants.
2. Recruit Stroke participants older than 18 years, with a history of brain injury in the middle cerebral artery (MCA) distribution, have the ability to complete the Fugl-Meyer Scale, maintain a full range of eye movements^35,36, have the abili.......

Discussion

The advent of eye and hand tracking systems as available tools for objectively exploring the characteristics of ocular-manual motor systems has accelerated research studies, enabling a nuanced recording approach for an essential task in daily activities – eye-hand coordination. Many natural action-dependent tasks are visually guided and depend on vision as a primary sensory input. Gaze is programmed through ocular motor commands which point central vision at key spatial targets; this information is pivotal and assi.......

Materials

Name	Company	Catalog Number	Comments
27.0" Dell LED-Lit monitor	Dell	S2716DG	QHD resolution (2560 x 1440)
ASUS ROG G750JM 17-Inch	AsusTek Computer Inc
Eye Link II	SR-Research	500 Hz binocular eye monitoring 0.01 º RMS resolutions
Matlab	MathWorks
Polhemus MicroSensor 1.8	Polhemus		240 Hz, 0.08 cm accuracy