FIGURE 2.

Hypothesized changes in neural vestibular response to HDBR + CO₂. We hypothesized three different longitudinal patterns of brain change: (A) Cumulative change, in which brain changes would slowly increase over the course of HDBR + CO₂, followed by recovery after the conclusion of HDBR + CO₂. (B) Instant change, in which brain changes would immediately onset after the start of HDBR + CO₂, followed by recovery post-HDBR + CO₂. (C) Instant change, in which brain changes would immediately onset the start of HDBR + CO₂, but begin recovery during bed rest. We tested each of these hypotheses by using the contrast vectors shown here as weights in our longitudinal statistical model which assessed brain changes over all six time points for the HDBR + CO₂ group. Solid lines depict the positive version of each contrast; dotted lines depict the negative version of each contrast.