Time matters: Integration of time information into memory processes
In 2014 John O´Keefe, May-Britt Moser and Edvard I. Moser were honored with the Nobel Prize in Physiology and Medicine for their work on cells that constitute a positioning system in the brain. Special cells, place and grid cells, enable the brain to orientate within the environment, allowing us to know where we are, how to navigate from one place to another and to form and express spatial memories. For animals both spatial navigation and spatial memories are essential to enhance fitness and survival based on the timely relocation of food sources and mating partners and the avoidance of predators which often establish typical hunting routes. But how are the circadian clock and memory circuits connected? A recent study illustrated for the first time that Drosophila is able to form time-related odor-sugar memories, where flies learn that one odor is coupled to reward in the morning while a second odor to the same reward in the afternoon. As a result of this finding Drosophila now appears to be a suitable model system to identify the neuronal correlates underlying time-related memories. I will address where in the brain these memories are stored and how time information delivered by clock neurons is integrated in memory circuits. On top, my aim is to unravel whether flies can link time to spatial information in order to form time-place memories, which are well-known in invertebrate (bees, ants) and vertebrate species (rats, mice). This would allow for the first time to identify the neuronal correlates enabling animals to be in the right place at the right time.