Effects of sex steroids on maternal motivation in the common marmoset (Callithrix jacchus): Development and application of an operant system with maternal reinforcement.

Abstract

We developed an operant paradigm for measuring effects of reproductive steroids on maternal motivation in common marmosets (Callithrix jacchus). Conditioned response regulated females' exposure to maternal reinforcement. Nulliparous females (n = 15) with experience with infants in social groups were subjects. The paradigm was validated by examining (a) effects of reinforcing stimuli on affective behavior in a nonoperant paradigm, (b) responsiveness of operant performance to changes in reinforcing stimuli and reinforcement schedule, (c) changes in operant responding due to omission of reinforcement, and (d) relation between operant responding and species-typical maternal behavior. In pregnant females, (n = 4), frequency of bar pressing and estradiol:progesterone ratio were maximal just before birth. Nonpregnant females (n = 3) treated with progesterone and estradiol to mimic late-pregnancy steroid profiles showed increased operant maternal behavior.

Neural circuits underlying crying and cry responding in mammals

“…Many types of studies that are part of the large field of cry research can contribute. With respect to hormonal modulation of the responsiveness to cries, evidence exists in humans [28] and non-human primates [94,95,96] that hormonal status influences responsiveness to cries. This work supplements the extensive evidence using rodents as research subjects that hormonal status has a profound influence on maternal responsiveness to infants, some of which was reviewed earlier in this paper.…”

Opportunistic mothers: female marmosets (Callithrix kuhlii) reduce their investment in offspring when they have to, and when they can

“…Primate maternal care was long thought to be relatively independent of endocrine processes (e.g., Coe, 1990;Pryce, 1992Pryce, , 1996Maestripieri, 1999). However, recent correlational and experimental studies have implicated hormonal factors in the regulation of maternal competency and caregiving motivation in a number of primate species (e.g., humans, Homo sapiens: Fleming et al, 1997a; Japanese macaques, Macaca fuscata: Bardi et al, 2003b;pigtail macaques, M. nemestrina: Maestripieri and Zehr, 1998;rhesus macaques, M. mulatta: Holman and Goy, 1995; savannah baboons, Papio hamadryas: Bardi et al, 2004; western lowland gorillas, Gorilla gorilla gorilla: Bahr, 1995), including marmosets and tamarins (e.g., common marmosets: Pryce, 1993;Pryce et al, 1993Pryce et al, , 1995red-bellied tamarins, S. labiatus: Pryce et al, 1988;Pryce, 1993; Wied's black tufted-ear marmosets: Fite and French, 2000). There is also good reason to believe that withinfemale variation in callitrichid maternal caregiving effort corresponds to within-female variation in endocrine status.…”

The biology of human parenting: insights from nonhuman primates

“…This difference was found in females without previous caregiving experience, but not in experienced mothers. In a study of common marmosets, nonpregnant females treated with estrogen and progesterone in concentrations similar to those of late pregnancy showed a signi®-cantly higher motivation to interact with infants than nontreated females [81]. Maternal motivaton was measured in an experimental apparatus in which females could press a bar to see an infant and simultaneously interrupt a tape recorder playing infant distress calls.…”