Sustaining Aviator Performance During Extended Operational Flight

Volunteers will first schedule an appointment to complete informed consent, screening procedures and meet with study physician. After eligibility is verified, volunteers will complete baseline assessments. At the completion of baseline assessments volunteers will be scheduled for their return visits and will be given their actiwatch. Scheduling will occur such that there is at least 16 hours' time between baseline assessments and their first treatment visit, whereas treatment visits will be scheduled such that there is at least 48 hours between visits. Stimulation will be counterbalanced with at least 48 hours between deliveries to allow for a washout period (Nitsche & Paulus, 2001). Scheduling will be done such that individual participants are always scheduled at the same time of day to control for any effects of circadian rhythm and individual differences.

Visit 1: Test scheduling, informed consent, screening procedures and baseline assessments.

During this visit, subjects will be informed that they should have 8 hours of sleep the night before each testing session, with a minimum of 6 accepted for participation (confirmed by an actiwatch and self-report). A minimum of 6 hours will be accepted to avoid potential loss of subjects who are not able to obtain 8 hours. However, 8 hours will be stressed to encourage subjects to be well rested prior to the testing days. They will also be instructed to refrain from taking over the counter medications which may induce drowsiness throughout the duration of the study, and refrain from the use of any stimulants including caffeine for a minimum of 16 hours prior to study participation, avoid alcohol use for a minimum of 24 hours prior to participation, and avoid the use of nicotine for a minimum of 2 hours prior to the study. These are requested to obtain clean physiological recordings (e.g., Gilbert, Dibb, Plath, & Hiyane, 2000 [caffeine, nicotine]; Kähkӧnen, Wilenius, Nikulin, Ollikainen, & Ilmoniemi, 2003 [alcohol]). If the participant reports use of a stimulant, medication inducing drowsiness, nicotine, alcohol, or the actiwatch indicates less than 6 hours of rest, the participant will be released from the study for that day and asked to reschedule. In the event that the actiwatch fails, confirmation will rely on self-report and be recorded within the study log.

Following informed consent, subjects will complete a medical history questionnaire with a study physician that includes caffeine consumption habits to determine any possible side effects due to caffeine withdrawal. A member of the research team will measure and record the subject's vital signs (temperature, respiration rate, blood pressure, pulse, and oxygen saturation) on the medical history questionnaire. The study physician will review the medical history questionnaire and vital signs to make a final determination regarding eligibility. In addition to determining eligibility, the study physician or medical practitioner will discuss with the subject regular caffeine consumption habit and whether the subject is likely to experience any negative side effects associated with caffeine withdrawal (e.g., headache). If determined to be eligible by the study physician, subjects will then be enrolled in the study, complete the volunteer registry database form, receive the actiwatch and be provided verbal instructions on its use and be given a handout of participation guidelines. After receiving the actiwatch and guidelines, the subject will be offered the opportunity for stimulation familiarization. This will entail applying the stimulation at the prescribed intensity (2 mA) for a duration of 5 minutes, with the anode at F3 and cathode on the contralateral bicep (right arm). The purpose of this will be to allow the subject to experience what the stimulation feels like so that they know what to expect for the stimulation days. After stimulation has been applied, the electrodes will be removed and the subjects will complete the following questionnaires: demographic questionnaire, Morningness-Eveningness Questionnaire (MEQ) , Adult ADHD Self Report Scale (ASRS), Sleep Timing Questionnaire (STQ), Beck Depression Inventory (BDI), Shipley's Institute of Living Scale (SILS), Convergence Insufficiency Symptom Survey (CISS), Samn-Perelli Fatigue Scale, Short Stress State Questionnaire (SSSQ), Behavioral Inhibition / Avoidance Scales (BIS/BAS), Karolinska Sleepiness Scale (KSS), and Profile of Mood States - Short Form (POMS-SF). The subject will next complete a baseline session of the Rapid Visual Information Processing Task (RVIP) and Conners' Continuous Performance Task (CPT). Following completion of questionnaires, the electroencephalogram will be placed on the subjects and baseline measurements will be taken, which is a series of three computerized tasks provided by Advanced Brain Monitoring (ABM Tasks) which will be used for baseline, and pre- / post-stimulation EEG measurements. Subjects will then meet with the research pilot who will go over the flight tasks required of this study and escort the subject into the simulator for familiarization and baseline flight performance data collection. During the familiarization flight, the research pilot will ensure the subject is able to meet prescribed flight standards such as maintain specified headings, airspeeds and altitudes with minimal input/prompts, which will be recorded on the flight standards sheet. The baseline flight will consist of a scenario similar to, but not exact, as the scenarios that will be performed on treatment days. Baseline performance and EEG will be recorded and archived for analyses/interpretation. Subjects will be released at this point for the day.

Visits 2-3: tDCS stimulation test sessions.