Experimental protocol

Flow chart of the experimental protocol for water maze test is given in Supplementary Fig. ^S7B. Animals were divided into 6 groups each containing 6 animals (n = 6). The first experimental day was dedicated to swimming training in the absence of the platform. During the subsequent days, the rats were given four training-trials sessions per day to locate the platform (with the platform in place). The inter training trial interval of 5 min was kept. During this learning phase, rats were placed randomly in the pool at selected locations and allowed to search the platform. The time taken from starting point to the escape from water onto the hidden platform (escape latency; learning and reference memory test {1^st test}) was measured in each training session. Each trial was ended if the animal arrived at the platform or after 120 s, whichever came first. Animal failing to arrive at the platform in 120 s were guided onto it. The rat was allowed to remain on the platform for 30 s after each hidden-platform trial. The location of the platform was fixed during the entire test period.A probe trial session was carried out on each day after 2 hr of last escape latency test, wherein platform was detached from the pool and rat were allowed to explore for the platform for 120 s. The time spent in the target quadrant was considered as a measure of spatial memory retention (2^nd test).