Abstract
This paper is intended as an overview of recent studies which examine the role of the cholinergic (ACh) or the dopaminergic (DA) system in time perception by animals, especially, rats. An information processing model which includes an internal clock, a reference memory, and a decision process was proposed as a substrate of time perception, and it has been revealed which neural transmitter systems involves in these three functions. For example, many studies by Meck and his colleagues have suggested that ACh involves in reference memory, and DA (especially D2 subtype) involves in clock. Later studies, however, do not necessarily support these results. For example, some researches reported that suppression of ACh induced increase in threshold in information processing model, and D2 is not unique dopaminergic subtype involving in clock. After reviewing these results, some issues to be considered in future studies will be pointed out. (Japanese Journal of Physiological Psychology and Psychophysiology, 21 (1) : 49-58, 2003.)
