Figure 1. Subarachnoid hemorrhage leads to long term spatial memory loss due to NMDA receptor mediated abnormalities in late long-term potentiation (L-LTP) that occur between the third and sixth day.

Barnes maze (BMT) and Morris water maze (MWM) analysis completed on the same cohort of animals over the first 9 days (BMT) and one month after (MWM) SAH or Sham. (A) There was significantly worse performance on BMT in animals in the SAH group. (B) This was consistent in the MWM performed at one month after SAH/Sham suggesting that the spatial memory deficits after SAH are present early and sustained as late as a month. (C) The diagram shows the experimental design of the electrophysiology experiments performed with stimulation of Schaffer collateral fibers between the CA3 region of the hippocampus and the CA1 region with acquisition of data from synapses between Shaffer collateral axons and pyramidal cell bodies. (D) The EPSP slope vs. time graph shows significantly preserved L-LTP on day 3 in SAH animals compared to Sham (n=3 animals/group with 7 slices). (E) At day 6, SAH animals lose L-LTP while Sham do not (n=3 animals/group with 9 slices). (F) Isolation of the NMDA receptor using bath conditions shown in the figure reveal continued loss of L-LTP suggesting the NMDAR (and not the AMPAR) is responsible for the effect (n=3 animals/group with 6 total slices). (G) shows a graphical display of the difference in L-LTP between SAH and sham at day 3, 6 and at day 6 with NMDA isolation.