Impaired Attentional Processing During Parabolic Flight

Abstract

Previous studies suggest that altered gravity levels during parabolic flight maneuvers affect spatial updating. Little is known about the impact of the experimental setting and psychological stressors associated with parabolic flight experiments on attentional processes. To address this gap, we investigated the level of alertness, selective and sustained attention in 1 and 0 g using a Go/No-Go Continuous Performance Task. We also identified several parameters associated with the experimental set-up of a parabolic flight that could be expected to affect attentional processing. These included the use of scopolamine, sleep quality prior to the flight day, participant's stress level as well as mood and anxiety state before and after the parabolic flight. We observed a deterioration in attentional processing prior to the first parabola that was further aggravated in weightlessness and returned to baseline after the last parabola. Reaction Time, Hit and False Alarm Rate were moderately correlated with self-reported anxiety state, but not cortisol levels or emotional states. The use of scopolamine had minor effects on Reaction Time. Our results confirm previous studies reporting impairments of cognitive performance in 0 g, and highlight important aspects that should be considered for the design of behavioral research experiments in future parabolic flight campaigns.

Keywords: adverse effects; anxiety; attention; human; microgravity; scopolamine.

FIGURE 1

Schematic overview of the study design. Four participants were tested on each flight day. MSSQ, Motion Sickness Susceptibility Questionnaire; POMS, Profile of Mood States; STAI Y-A/Y-B, State-Trait Anxiety Inventory Form Y Part A/B; CPT, Continuous Performance Task; PVT, Psychomotor Vigilance Task, Fam, familiarization session; VIS Morgen, sleep questionnaire; P, Parabola; syringe represents subcutaneous scopolamine injection.

FIGURE 2

Experimental set-up. (A) Participants performing the Continuous Performance Task (CPT) in a controlled free-floating position. (B) Participants performing the psychomotor vigilance test (PVT) using a diving computer that was attached to participants’ wrist. During both tasks, two participants were tested at the same time.

FIGURE 3

CPT performance. (A) Reaction Time of target stimuli in ms; (B) Hit Rate (correct reactions to target stimuli) in percentage; (C) False Alarm Rate (reactions to non-targets) in percentage; (D) d’ (indicator for task sensitivity). Data is presented as marginal means ± SE and was collected at the following points in time: Pre-flight (30 min after scopolamine injection), inflight at 1 g before the first parabola (1 g before P0.), during microgravity (0 g), at 1 g after the last parabola (1 g after P30), and after landing (Post-flight). *P < 0.05, **P < 0.01, ***P < 0.001 compared to pre-flight.

FIGURE 4

Time course of salivary cortisol levels. Baseline saliva was collected between 9 am and noon on the day of arrival. Two different patterns could be observed, with the highest measured cortisol either after P30 (High-P30) or before P0 (High-P0). Orange line represents participants of High-P30, violet line represents participants of High-P0, dark blue line shows data of all participants. Data are presented as marginal means ± SE. *P < 0.05, **P < 0.01, ***P < 0.001 compared to baseline, ^‡P < 0.05, ^‡‡P < 0.001 compared to High-P0.