Maternal care can rapidly induce an odor‐guided huddling preference in rat pups

Abstract

Olfactory-guided huddling is learned and expressed by Postnatal Day (PND) 15, when rat pups huddle preferentially with conspecifics or with targets bearing an odor previously associated with maternal care. Experiment 1 replicated this induction of an odor-guided huddling preference with a truncated regime of conditioning with a scented foster dam. Pups exposed to an odor in association with foster maternal care during five daily 2-hr sessions on PNDs 1–5, 5–9, or 10–14, but not pups merely exposed to the odor, displayed a huddling preference for the conditioned odor, but only when conditioning commenced after PND 5. Experiment 2 demonstrated that a single, 2-hr exposure to a scented foster dam can induce a huddling preference in pups. Analysis of maternal behavior during the 2-hr conditioning sessions on PND 14 revealed that frequency of maternal hovering over pups, but not licking/grooming or duration of contact, was associated with induction of the odor preference.

Warmth from skin‐to‐skin contact with mother is essential for the acquisition of filial huddling preference in preweanling rats

“…We were then able to quantify and correlate specific elements of maternal behavior with the strength of each individual pups' olfactory preference, measured in the PD 15 test. Somewhat surprisingly, our measure of maternal licking/grooming and simple physical contact were not associated with the huddling preference (Kojima & Alberts, 2009). The frequency with which mother rats assumed a hovering posture over the pups did, however, correlate with the subsequent filial preference.…”

“…In our previous investigation of olfactory preferences acquired by rat pups during a 2-hr conditioning session, we observed the interactions of a scented foster dam with two individually marked, 14-dayold littermates, via an overhead camera (Kojima & Alberts, 2009). Of the maternal behaviors quantified from those video records, hovering frequency was the behavioral variable most closely associated with the formation and levels of the pups' affiliative preference.…”

“…Typically, studies designed to relate maternal care to developmental outcomes have focused on specific behaviors directed by a mother to the offspring. Our previous study (Kojima & Alberts, 2009) is one such example. In the present study, however, we devised a novel measure of behavioral interaction, namely ''skin-to-skin (STS) contact'' between mother and individual pups.…”

“…Recently, we reported that a single, 2-hr period of cohabitation with a scented foster dam on PD 14 was sufficient to induce a filial preference expressed in a huddling test on PD 15 (Kojima & Alberts, 2009). This single-session procedure made it possible to observe and to quantify the dam-pup interactions throughout the entire learning experience.…”

“…Gottlieb (1976) applied the term induction to define the formation of a perceptual preference by such experience-dependent direction or canalization (cf., p. 37). Kojima and Alberts (2009) re-visited the developmental induction of filial huddling in rats with an investigation that revealed considerable flexibility with respect to when interactions with a scented foster dam can induce a filial preference, and how much (or how little) maternal interaction is sufficient for learning to occur. The results indicated that a short (2 hr) period of interaction with a scented, maternally active foster dam is sufficient to induce a filial huddling preference for an odor borne by the dam.…”