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Scientists have discovered two neural circuits that determines the way time-linked memories are formed and stored inside the brain. 

It is a known fact that memories of events - called episodic memories, reside in the hippocampus area of the brain. The part also receives information from the entorhinal cortex that processes sensory information. 

This study addresses some questions regarding how brain associates objects and time. 

The study conducted by researchers at Massachusetts Institute of Technology conducted tests on mice in 2011. First, they linked memories of two separate sensory experiences. Sensory experiences were combination of sound and an electric shock that occurred 20 seconds apart. Subsequently they analyzed the mice's neural responses and located the circuit that connected the hippocampus to the enthorhinal cortex in the mouse brains. 

Based on a previous study in 2011, researchers discovered a new second circuit that could suppress the monosynaptic circuit. In the previous study researchers at MIT were unable to find an existing link between memories of the sound and shock that remained for more than 20 seconds. Nevertheless, in this study the team was able to manipulate this recall period as well as were able to make it longer and shorter. 

Researchers believed that the balance of two neural circuits allowed human to respond to signs of approaching danger without being over-sensitive to sensory information. 

"It's important for us to be able to associate things that happen with some temporal gap," said study author Prof. Susumu Tonegawa, who is a member of MIT's Picower Institute for Learning and Memory in a press release. "For animals it is very useful to know what events they should associate, and what not to associate."

The study has been published in the journal Science.