Figure 1.

Cerebrovascular response to visual–spatial task. Mean arterial pressure (MAP), posterior cerebral artery (PCA) mean flow velocity (vmean), cerebrovascular conductance (CVC), and partial pressure end-tidal carbon dioxide (PETCO₂) response during verbal fluency testing. Gray line represents able-bodied individuals, black dashed line represents spinal cord injury (SCI) before midodrine, thick black line represents spinal cord injury after midodrine (SCImido). The black filled rectangle represents the 30-second activation period, whereas the six smaller empty rectangles represent 5-second bins from the activation period. Mean arterial pressure and PETCO₂ did not change significantly in response to the visual task. Posterior cerebral artery mean flow velocity and PCAcvc did not significantly increase in SCI. Posterior cerebral artery mean flow velocity and PCAcvc increased significantly during activation in SCI after midodrine; however, this response was still reduced as compared with the significant response in AB. AB, able-bodied control; CBF, cerebral blood flow.