Subarachnoid hemorrhage leads to early and persistent functional connectivity and behavioral changes in mice
Aneurysmal subarachnoid hemorrhage (SAH) leads to significant long-term cognitive deficits. Studies in survivors of SAH show an association between persistent cognitive deficits and alterations in resting state functional connectivity (RSFC). However, modalities commonly used to assess RSFC in humans, such as fMRI, have practical limitations in small animals. Therefore, we used non-invasive functional optical intrinsic signal imaging to determine the effect of SAH on measures of RSFC in mice at early (day 4), intermediate (1 month), and late (3 months) time points after prechiasmatic arterial blood injection. We assessed Morris water maze, open field test, Y-maze, and rotarod performance from approximately 2 weeks to 3 months after SAH induction. We found qualitative and quantitative differences in seed-based connectivity maps between sham and SAH mice. SAH reduced motor, retrosplenial and visual seed-based connectivity indices, which persisted in retrosplenial and visual cortex seeds at 3 months. Seed-to-seed connectivity analysis confirmed attenuation of correlation coefficients in SAH mice, which persisted in predominantly posterior network connections at later time points. Seed-independent global and interhemispheric indices of connectivity revealed decreased correlations following SAH for at least 1 month. SAH led to Morris water maze hidden platform and open field deficits at 2 weeks, and Y-maze deficits for at least 3 months, without altering rotarod performance. In conclusion, experimental SAH leads to early and persistent alterations both in hemodynamically-derived measures of RSFC and in cognitive performance.