Temporal patterns of schedule-induced drinking and pawgrooming in rats exposed to periodic food

Abstract

Five rats were exposed to fixed-time food schedules, ranging from 30 to 480 sec. Three rats displayed a postfood pattern of schedule-induced drinking, with short latencies from food delivery to drinking at all interfood interval durations. In contrast, drinking for the other 2 subjects tended to occur at lower overall levels, and drinking bouts frequently began in the middle of the interfood interval, such that the latency from food delivery to drinking increased dramatically as the interfood interval increased. Observation of these 2 subjects revealed that another form of licking-pawgrooming-occurred reliably after food delivery and before drinking bouts. A betweensubject comparison of the 3 postfood drinkers and the 2 pawgroomers revealed that, in addition to a common topography (repetitive licking), pawgrooming and drinking were similar with respect to their temporal locus, relation to the interfood interval, and extinction baseline levels. These similarities suggest that drinking and pawgrooming are induced by a common mechanism. Cohen, Looney, Campagnoni, and Lawler's (1985) two-state model of reinforcer-induced motivation provides a useful framework for the interpretation of these results.When hungry rats receive small portions of food intermittently, distinctive behaviors emerge in the period following each food delivery. These behaviors include excessive drinking, chewing and ingesting nonfood substances (pica), attack, general locomotor activity, and responding to change the stimuli associated with the food schedule (time-out responding) (Falk, 1971(Falk, , 1981Killeen, 1975;Staddon, 1977). Falk (1971) coined the term adjunctive to call attention to similarities among these behaviors, and to distinguish them from instances of classical or operant conditioning. The temporal locus of adjunctive behaviors has been particularly important to speculations that they reflect an arousing (Cantor, 1981;Cook, Wallace, & Singer, 1983;Killeen, 1975;Wayner, 1970) or aversive (Azrin, Hutchinson, & Hake, 1966;Rosellini, 1985;Staddon, 1977) Cohen, Looney, Campagnoni, and Lawler (1985) and Campagnoni, Lawler, and Cohen (1986) reported interesting differences in the temporal properties of several schedule-induced (adjunctive) behaviors in pigeons. They found that attack is reactive, occurring immediately postfood and reaching peak levels at the same absolute time (5-10 sec after food delivery), regardless of the overall length of the interfood interval. In contrast, three other induced behaviors, increased general activity, time-out responding, and movement away from the food site, occur after attack and exhibit scalar (proportional) timing (Gibbon, 1977). In other words, the onset of these activities depends on the overall interval between food deliveries, that is, they reach peak levels at the same relative point (25 %-35 % of the interfood interval) after food. Cohen et al. (1985) have proposed a two-state model of reinforcer-induced motivation as a way of interpreting these results. The model states that differences ...

The organization and temporal properties of appetitive behavior in rats

“…In contrast, behavior occurring immediately after food may appear time bound to food presentation (Lucas et aI., 1988)-that is, the peak of responding occurs at the same absolute time after food, regardless of the length of the IF! (Campagnoni, Lawler,& Cohen, 1986;Cohen, Looney, Campagnoni, & Lawler, 1985;Lawler & Cohen, 1992). Thus, when rats are exposed to different lengths of IFIs, ranging from 16 to 512 sec, responses such as waiting by the feeder, rearing, pawgrooming, and drinking reach a maximum level during the same 12-15-sec interval after food presentations and then rapidly decrease (Lawler & Cohen, 1992;Lucas et aI., 1988).…”

“…(Campagnoni, Lawler,& Cohen, 1986;Cohen, Looney, Campagnoni, & Lawler, 1985;Lawler & Cohen, 1992). Thus, when rats are exposed to different lengths of IFIs, ranging from 16 to 512 sec, responses such as waiting by the feeder, rearing, pawgrooming, and drinking reach a maximum level during the same 12-15-sec interval after food presentations and then rapidly decrease (Lawler & Cohen, 1992;Lucas et aI., 1988). However, for a response, such as general locomotion, that predominantly occurs in the middle of the IFI, the time at which it reaches a maximum level increases proportionally with increases in the IFI length.…”

“…Gibbon and Balsam (1981), in conditioning single conditioned stimuli (CSs), and Palya and Pevey (1987), using interfood clock training, have shown that the initiation of the keypeck response in pigeons is scalar, but little work has been done with other responses and with asymptotic responding. Previous research on adjunctive behavior has provided information about the effect ofIFI length on the distribution of multiple responses (Cohen et a1., 1985;Lawler & Cohen, 1992;Lucas et a1., 1988), but their relation to external stimuli and the effects of the IFI length on that relation are not clear.…”

“…According to this view, an animal progresses through an organized sequence of search modes (motivational states) between food presentations, in which each mode controls a particular set ofresponses. For example, immediately after food, a rat is presumed to enter a postfood focal search mode, characterized by rearing, pawgrooming, and sniffing around the feeder area (Lawler & Cohen, 1992;Lucas et a1., 1988). Closer to the middle of the IFI, the rat enters a general search mode that is characterized by locomotion around the experimental chamber.…”

Comportamento adjunto: controvérsias e contribuições teóricas

“…Assim, demonstram a indução de comportamentos ainda não investigados, como por exemplo, lamber a pata em rato (Lawler & Cohen, 1992), hábitos orais excessivos em humano (Gramling, Grayson, Sullivan & Schwartz, 1997) e replicam em outras espécies os adjuntos já demonstrados no rato, como por exemplo, a defecação em pombos (Jarema, LeSage, & Poling 1995).…”