the hypothetical ability that allows humans to be constantly aware of the past and the future, i.e. mental time travel – a concept first hypothesised by Endel Tulving in the 1980’s. There seems to be some confusion about the definitions of episodic memory, and mental time travel. Episodic memory involves projecting oneself back in time and recollecting autobiographical events (times, places, associated emotions, and other contextual knowledge). Mental time travel involves the acquisition, retention and retrieval of autobiographical events to use for acute depictions of future trends and experiences. Therefore, mental time travel involves both past and future thinking, while episodic memory only deals with mentally traveling to the past.
Neural Signature of 'Mental Time Travel': Memories Formed in the Same Context Become Linked

Almost everyone has experienced one memory triggering another, but explanations for that phenomenon have proved elusive. Now, University of Pennsylvania researchers have provided the first neurobiological evidence that memories formed in the same context become linked, the foundation of the theory of episodic memory.

“What seems to be happening is that when patients recall a word, they bring back not only the thoughts associated with the word itself but also remnants of thoughts associated with other words they studied nearby in time.

This is why two friends you met at different points in your life can become linked in your memory. Along your autobiographical timeline, contextual associations will exist at every time scale, from experiences that take place over the course of years to experiences that take place over the course of minutes, like studying words on a list.”