Adjustment to intermittent access in rats drinking saccharin: I. Pauses in drinking

Hungry rats drink saccharin solutions avidly. When access to the cylinder is restricted, so that it is available during alternate 30-sec periods rather than continuously, rats adjust to this constraint so that total amount of lapping, over each period of a few minutes each, is defended. We show that the rats achieve this defense, in part, by pausing less often and for briefer periods between bursts. Log-survivorship analysis of the pauses in drinking suggests (a) that they are generated by two processes with different time constants, (b) that early in the session, both processes are suppressed when access is restricted; and (c) that later in the session, pauses reflecting the shorter-term process begin to appear, even if access is restricted. Therefore, adjustment to constraints on access is achieved in part by suppression or inhibition of two processes that generate pauses, and the suppression is relaxed earlier for the one with shorter time constant.