One week of maternal separation induces more frequent, but less predictable, maternal caregiving behaviors

Abstract

Rodent models of early life adversity disrupt typical interactions between dams and offspring, impacting pup development over the lifespan. Predictability of caregiver interactions is a critical feature of the environment, and unpredictability is associated with behavioral and cognitive deficits in offspring. In the maternal separation (MS) paradigm, dams are not able to engage with pups while they are separated, and maternal care is impacted even after pups and dams are reunited. Using a 3.5-h daily MS protocol in rats, the present study sought to compare diurnal patterns of maternal behavior, specifically predictability and fragmentation of care, between MS- and control-reared dams. Three observation periods were assessed (1430, 2330, and 0830) between postnatal days 8-9. Frequencies and durations of maternal behaviors were measured, including pup-directed licking/grooming, arched-back and passive nursing, and carrying pups, as well as non-pup-directed self-grooming, rearing, burrowing, nest-building, and eating. The frequency of nest entries was interpreted as a measure of fragmentation, and entropy rate was calculated from transitional probability matrices to measure predictability of maternal behavioral sequences. After dam-pup reunion, MS dams engaged in more bouts of nursing and licking/grooming and more nest entries, and behavioral sequences were less predictable than control dams. MS-induced enhancement of care is a replication of previous research, but unpredictability and fragmented care during MS is a novel finding, as these measures have not been previously reported for MS.