Simultaneous fMRI and tDCS for Enhancing Training of Flight Tasks

Abstract

There is a gap in our understanding of how best to apply transcranial direct-current stimulation (tDCS) to enhance learning in complex, realistic, and multifocus tasks such as aviation. Our goal is to assess the effects of tDCS and feedback training on task performance, brain activity, and connectivity using functional magnetic resonance imaging (fMRI). Experienced glider pilots were recruited to perform a one-day, three-run flight-simulator task involving varying difficulty conditions and a secondary auditory task, mimicking real flight requirements. The stimulation group (versus sham) received 1.5 mA high-definition HD-tDCS to the right dorsolateral prefrontal cortex (DLPFC) for 30 min during the training. Whole-brain fMRI was collected before, during, and after stimulation. Active stimulation improved piloting performance both during and post-training, particularly in novice pilots. The fMRI revealed a number of tDCS-induced effects on brain activation, including an increase in the left cerebellum and bilateral basal ganglia for the most difficult conditions, an increase in DLPFC activation and connectivity to the cerebellum during stimulation, and an inhibition in the secondary task-related auditory cortex and Broca's area. Here, we show that stimulation increases activity and connectivity in flight-related brain areas, particularly in novices, and increases the brain's ability to focus on flying and ignore distractors. These findings can guide applied neurostimulation in real pilot training to enhance skill acquisition and can be applied widely in other complex perceptual-motor real-world tasks.

Keywords: HD-tDCS; aviation; basal ganglia; brain connectivity; cerebellum; dorsolateral prefrontal cortex; fMRI; neuroergonomics; neurostimulation; training.

Figure 1

(A) Participant prepared for the experiment. (B) Magnetom Prisma 3T fMRI. (C) Projected viewpoint from the cockpit in the flight simulator via a mirror above eyes, with images displaying the target runway and the auditory task at the start of each trial. (D) Starstim fMRI-safe HD-tDCS placed on the head. (E) NATA Technologies fMRI Joystick in the right hand. (F) fMRI-safe 2-button controller for the auditory task in the left hand.

Figure 2

Starstim HD-tDCS with the anode over AF8 (indicated by the red circle) and cathodes over Fpz and T8 to stimulate the right dorsolateral prefrontal cortex.

Figure 3

Average change in landing g-force for all subjects, where lower bars indicate a greater improvement in performance from run 1 (*** p < 0.001, error bars are SE). (A) Performance separated by run and tDCS condition. (B) Post-pretraining separated by experience and tDCS condition.

Figure 4

Differential brain activity for the active Stim > Sham group for the contrast focusing on selective attention task-dependent learning-related activity Post((FlyLsnHard-FlyLsnEasy)—(FlyNoLsnHard-FlyNoLsnEasy))—Pre ((FlyLsnHard-FlyLsnEasy)—(FlyNoLsnHard-FlyNoLsnEasy)) p < 0.001 uncorrected. (a) Rendered on the surface of the brain’s left, top, and right views. (b) Horizontal slice through the cerebellum (centered at MNI −32,−50,−26), ROI analysis for left cerebellum pFWE < 0.05 corrected for multiple comparisons. (c) Horizontal slice through caudate of basal ganglia (centered at MNI -14,14,12), ROI analysis for left caudate pFWE < 0.05 corrected for multiple comparisons. (d) Horizontal slice through caudate of basal ganglia (centered at MNI 10,20,−2), ROI analysis for right caudate pFWE < 0.05 corrected for multiple comparisons.

Figure 5

Differential brain activity for the tDCS stim > sham group for the contrast focusing on selective attention task-dependent activity during training tDCS session training ((FlyLsnHard-FlyLsnEasy)—(FlyNoLsnHard-FlyNoLsnEasy)) p < 0.001 uncorrected. Rendered on the surface of the brain’s left, top, and right views. The focus of differential activity is centered at MNI 34,46,28, ROI analysis for right DLPFC (using anatomical mask from Sallet et al., 2013) pFWE < 0.05 corrected for multiple comparisons.

Figure 6

Differential brain activity for tDCS stim > sham group for the psychophysiological interaction connectivity analysis using the DLPFC as the seed ROI and the contrast focusing on selective attention task-dependent activity during training tDCS session training ((FlyLsnHard-FlyLsnEasy)—(FlyNoLsnHard-FlyNoLsnEasy)) p < 0.001 uncorrected. Differential activity is shown on coronal, sagittal, and horizontal slices through the cerebellum (centered at MNI −32, −50, −40). Spherical small volume correction analysis centered at MNI 32, −50, −26 with a radius of 15mm showed significant differential connectivity between DLPFC and cerebellum pFWE < 0.05 corrected for multiple comparisons.

Figure 7

Differential brain activity for the tDCS stim < sham group for the contrast focusing on the auditory task during difficult compared to easier flying conditions during the training tDCS session Training(SndLsnHard-SndLsnEasy) p < 0.001 uncorrected. Rendered on the surface of the brain’s left, top, and right views. ROI analyses in the left primary auditory cortex, left dorsal premotor cortex, and ventral Brodmann area 44 showed significant differential activity pFWE < 0.05 corrected for multiple comparisons.