Determining Which Regions of the Brain Are Active During Flight Simulation at Separate Timepoints During Training

Overview

The overall objective is to identify the cognitive circuits associated with military aviator performance by analyzing what anatomic regions of the brain are functionally "active" (neuronal circuit) while being performing virtual flight simulations, the Precision Instrument Control Task (PICT). The flight simulation test will be conducted at two separate timepoints while the subject is receiving a Functional Magnetic Resonance Imaging (fMRI) scan to evaluate which anatomic and functional brain function is associated with precise performance. By scanning at multiple time points we aim to quantify changes in functional and anatomic connectivity that occur throughout the course of training.

Establishing, maintaining, and quantifying readiness in high performance individuals and populations, such as active-duty pilots, remains a significant challenge in the DoD. Proficiency in pilots, like other high-performance populations, consists of mastery of multiple tasks. Some tasks, such as G-straining relies upon known approaches to strengthen musculoskeletal endurance of the buttocks, quadriceps, and hamstrings with well-defined exercises to improve tolerance to high G-loads. Thus, if particular pilot or trainee is struggling with near G-induced loss of consciousness, clear training regimens can be prescribed to strengthen the necessary muscles to improve performance. However, cognitive tasks, such as precisely controlling an aircraft to maintain a specific trajectory, despite the presence of crosswinds and other perturbations, is more difficult to understand and train. Until several years ago, there was no clear approach in defining the neuronal circuit necessary for such tasks. Without that understanding of this cognitive circuitry, it is difficult if not impossible to prescribe targeted and efficient training modalities to strengthen its performance. Neuroergonomics By detecting subtle changes in blood flow to different regions of a brain during a task, functional Magnetic Resonance Imaging (fMRI) can localize the most active regions of the brain at any point in time. This technology is advancing rapidly and for specified tasks is demonstrating remarkable consistency in multiple cortical regions of the brain employed during the same task, between different individuals. The multiple regions activated during a particular task are often referred to as "functionally connected." In addition, these functionally connected regions of the brain activated during a cognitive task share an analogy with the muscles activated to accomplish a physical task. Another MRI technology can quantify the connectivity through axons located in white matter (the wires in the brain) and measure the strength of the physical connection between different regions of the brain - termed structural connectivity. Interestingly, like muscles after prolonged training, the "strength" of connections between specific regions can show measurable increases with training and repetition. However, because of the high magnetic fields existing within MRI machines, complex devices or video displays could not traditionally be used when scanning subjects. As a result, early tasks within scanners (termed paradigms) were often serial and not representative of the highly dynamic tasks of flying. But high-resolution display systems are available that are MRI compatible - which can generate high resolution and more immersive environments. Furthermore, increasingly sophisticated input devices have also been developed that are MRI compatible and now it is possible to include a realistic flight stick to control pitch, roll, and throttle of simulated airframes. Thus, the field of neuroergonomics -- analyzing how the brain behaves during everyday operations in a more naturalistic way - can be applied to aviation. Recent fMRI work has started to identify the neurocircuitry involved in specific flying tasks such as aerial pursuit. Other work has identified regions of the brain activated during cognitive overload where subjects did not perceive audible alarms while flying in a simulator. Furthermore, specific brain regions appear activated during video feedback after performing a complex landing task. Thus, the brain regions active during aerial pursuit, cognitive overload, and feedback - all pertinent to aviation training - are beginning to be identified. However, given that much of this data has been collected from amateurs - not highly experienced military pilots - its applicability to highly trained military aviators needs to be tested. Applying the techniques of neuroergonomics to improve military aviator performance will require two distinct steps: 1.) The neuroanatomic circuits associated with different aspects of high-performance aviation must be identified; and 2.) for each circuit, training paradigms will need to be identified to strengthen the neuroanatomic circuit of interest to track not only behavioral performance, but the neural correlates associated with enhanced performance. PICT Task -- MRI flight Simulation Challenges The Precision Instrument Control Task (PICT) flight simulator test is adapted from an existing human performance study, called "Wayfinding, Hypoxia, and Interceptive Performance in Pilots Executing Transitions" (WHIPPET), which is currently being conducted at the Brooks Research Altitude Chambers with the objective of measuring the piloting deterioration that results from moderate hypobaric hypoxia. The task generates quantitative metrics to assess the accuracy and swiftness with which a pilot can execute corrective control inputs while flying. The tasks will be adapted from their current psychophysical application for use in this neuroimaging application. Both piloting tasks will be rendered using the commercially available application software called XPlane (Laminar Research, Inc., Columbia SC), which is a PC-based simulation suite that uses believable flight controls and dynamic aircraft models to present high-fidelity simulated sorties with the visual characteristics and demands of real flight. XPlane has been used in psychophysical investigations of the effect of environmental stressors on human performance in a cockpit environment, and to identify areas of brain activation during the execution of simulated aerial pursuit tasks. For this application, XPlane will be employed to present the aerodynamic characteristics of an F/A-18F. The visual interface will include a forward "out-the-window" display incorporating a generic head-up-display (HUD) with climb-dive ladder, horizon and heading indicators, and digital airspeed and vertical velocity indicators. The display will be presented in the fMRI scanner using stereogenic goggles called the Visual System HD (NordicNeuroLab, Bergen, Norway) display mounted in the scanner via the Siemens Vida 64-channel headcoil, as has been employed successfully to construct interactive virtual reality platforms for fMRI research applications. This apparatus will present the experimental visual interface in 1920 x 1200-pixel format via stereoscopic goggles, with each eye's array extending approximately 52 x 34 deg (horizontal x vertical) in field of view. This configuration should provide ample resolution and angular subtense to produce virtual presence in the simulated environment. Specific Aims 1. Determine what portions of brain activity correlate with level of performance during flight simulation (PICT). 2. Determine the changes in brain activity that occur during two separate timepoints. 3. Determine what portions of brain anatomy correlates with level of performance during flight simulation (PICT). 4. Determine the changes in brain anatomy that occur during two separate timepoints.