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Combined effects of food deprivation
and food frequency on schedule-induced drinking in rats
José Luis Castilla
and Ricardo Pellón
Universidad Nacional
de Educación a Distancia, Spain
Food-deprived rats at 80% of their free-feeding weights were
exposed in sequence to fixed-time schedules of different food
frequencies (15-, 30- and 60-s, counterbalanced across animals).
Linear or bitonic functions related the rate of food presentation
with measures of licks per minute and licks per food-pellet,
respectively. On subsequent phases of the experiment, animals
were food deprived to 70% and 90% of their initial free-feeding
weights, and they were retested with the same fixed-time schedules
(one rat was also tested under a 120-s food frequency at the
70% weight condition). The functions relating food frequency
with measures of schedule-induced licking were shifted up and
right in the case of the 70% condition, and were shifted down
in the case of the 90% condition, in comparison to results obtained
under 80% food deprivation. Changes were also observed in the
distribution of licking within inter-food interval as a function
of food-deprivation level. A tendency was observed for temporal
distributions of licking to be displaced to the right as food-deprivation
decreased. These data are the first to investigate in a systematic
manner the interactions between food deprivation and food frequency
on the amount of schedule-induced drinking. Motivational variables
also modulate other environmental influences on adjuntive behaviour,
and the present results will be discussed in connection with
these other effects.
Keywords: schedule-induced drinking,
food deprivation, food frequency, rats |