Role of the Striatum and Hippocampus on Different Time Scales

Time processing is fundamental to survival and goal reaching in humans. Different time scales (seconds, minutes, and beyond) are processed through specific cognitive processes involving different neural representations. It is generally agreed that time scale in seconds-to-minutes range named "interval timing" would be anatomically linked to the striatum. Indeed, it is possible to demonstrate a deficit of interval timing processes in patients suffering from striatal damage (Huntington's disease). However, recent findings show involvement of a second brain structure, the hippocampus, in interval timing processing in the minutes range, suggesting an interaction between the striatum and hippocampus. Presumably, patients with hippocampal damage (Alzheimer's disease) would specifically show a decrease in performance for this minutes-range time scale. This study aims to provide a better understanding of the role of the striatum in the treatment of time and its interactions with other brain structures such as the hippocampus. More specifically, it is unclear whether the striatum plays a platform role that would always be involved regardless of the time scale, as suggested by the unified model of time or whether different brain structures is solicited according to the time scale, as suggested by the modular system model. In order to elucidate these issues, a potential double dissociation between brain structures and time scales will be tested.