Age-related differences in rats’ spontaneous alternation

Abstract

Fifteen-day-old rats made random choices in a T-maze, while adult levels of alternation (approximately 70%) were noted among 30-day-olds, Also, younger pups were insensitive to a lengthening of the intertrial interval, unlike older animals whose rate of alternation decreased when a l-h delay was interposed between arm entries, These findings are consistent with the hypothesis that hippocampal development is a factor in the ontogeny of postweaning locomotion. The unsystematic pattern of goal-arm selections among 15-day-olds suggests that ontongenetic variation in the utilization of stimuli may underlie developmental shifts in spontaneous alternation, Altman, Brunner, and Bayer (1973) have suggested that the 2-or 3-week-old domestic rat is behaviorally similar to the hippocampectornized adult of the species. Further, maturation rates of cells at the dentate gyrus and the development of cholinergic control over behavior are consistent with this brain-development hypothesis (Campbell, Lytle, & Fibiger, 1969;Douglas, 1972).This particular behavioral syndrome, typical of the young rat, includes: (a) elevated and persistent motor activity (Bronstein, Neiman, Wolkoff, & Levine, 1974;Campbell et al, 1969;Feigley, Parsons, Hamilton, & Spear, 1972), (b) considerable difficulty in the acquisition of a passive-avoidance task to a footshock US (e.g., Ricco & Marazzo, 1972), (c) impaired position-habit reversal (Harley & Moody, 1973), and (d) low levels of spontaneous alternation (Douglas, Peterson, & Douglas, 1973;Kirkby, 1967). The present paper describes attempts to replicate and to further understand the age-related differences in spontaneous alternation. EXPERIMENT IThe first experiment is a longitudinal investigation of alternation in the rat. MethodSubjects. Twenty-three male and 14 female rat pups served as Ss. These were derived from four Sprague-Dawley albino litters (9 or 10 pups/dam) born in the Brooklyn College laboratories. The animals were individually marked and housed with their mothers in plastic litter cages. Twenty-two days after parturition, the maternal females were removed from their offspring with all pups left behind in the litter boxes. When the young were 31 days old, they were rehoused, 2 to a cage (same-sex pairs), except for a few individually caged Ss, Purina Lab Chow and water were always available, and the colony was heated to about 74°F. The vivarium was brightly lighted from 8 a.m. to 2 a.m. daily, and Ss were run during the light part of the cycle, always at about the same time of day.Apparatus. One bottomless plywood T-rnaze, painted flat black, was the apparatus. The maze was 6.40 cm high and initially had a width of 6.35 em, but was widened to 10.80 cm throughout after the Ss were 31 days old. This enlargement was needed in order to accommodate the pups' growth. The apparatus was covered with clear Plexiglas, and three guillotine doors of white plastic divided the maze stem into a startbox and runway (each 20.32 cm long) and goal arms (each 28.85 em long). A 15-Wincandescent bulb, shaded ...

Ontogeny of spatial working memory in the subterranean rodentctenomys talarum

“…When short delays were interposed between the forced and choice runs in the spatial alternation task, 20‐day‐old pups made more errors than 40‐ and 60‐day‐old pups. This initial improvement in the spatial performance, comprised between 20 and 40 days after birth, coincides with evidence from other behavioral studies which also shown the appearance of spatial working memory in rats between 20 and 30 days after birth (Bronstein et al, 1974; Brown et al, 2005; Castro et al, 1987; Green & Stanton, 1989). Further changes in pups' spatial performance were also observed when longer intervals (10 min) were inserted between runs.…”

“…The late development of the hippocampus is reflected in the age‐dependent emergence of spatial memory observed in various rodent species. First works showed that while 15‐day‐old pup's rats made random choices in a T‐maze, adult levels of correct choices of 70% were observed among 30‐day‐old pups (Bronstein, Dworkin, & Bilder, 1974). Similarly, Castro, Paylor, and Rudy (1987) and Green and Stanton (1989) found ontogenetic differences in the development of short‐memory in rats.…”

The ontogeny of locomotion in rats: The influence of ambient temperature

“…Our studies of the possibility that the persistently active juvenile rat is exploring its environment disconfirmed the hypothesis, however. Two-weekold pups do not exhibit spontaneous alternation in a T maze (e.g., Bronstein, Dworkin, & Bilder, 1974), a response often used to signify exploration in rodents. Furthermore, Palese and Bronstein (1976) persistently active juveniles would not pattern their movements any differently than older animals when tested in a cross maze.…”

Aversive prenatal stimulation: Effects on behavioral, biochemical, and somatic ontogeny in the rat

“…No significant Trial 1 directional preferences were found. Alternation behavior did not consistently increase with age as expected (Bronstein et al, 1974;Douglas et al, 1973;Egger et al, 1973). However, whereas 17-day-old animals showed perserverative behavior or alternated at chance levels, 37-day-old animals in 5 of the 6 groups were alternating a t a reliable rate of approximately 65%.…”

“…Spontaneous motor activity (SMA) and spontaneous alternation (SA) were used to assess disruptions in behavioral ontogeny following prenatal treatment-exposure of the pregnant female to electric foot shock-as both of these behaviors show distinct developmental patterns (Bronstein, Dworkin, & Bilder, 1974;Campbell, Lytle, & Fibiger, 1969;Douglas, Peterson, & Douglas, 1073;Egger, 1973a,b;Pappas, Peters, Sobrian, Blouin, & Drew, 1975;Sobrian, Weltman, & Pappas, 1975) and have been linked to the development of serotonergic, cholinergic, and noradrenergic systems in the brain (Egger, Livesey, & Dawson, 1973;Swonger & Rech, 1972;Trimbach, 1972). The development of reflexes, physical features, and body weight were evaluated t o determine the extent to which somatic systems were affected.…”