A Bold View of the Lactating Brain: Functional Magnetic Resonance Imaging Studies of Suckling in Awake Dams

Abstract

Functional magnetic resonance imaging (fMRI) has been used to investigate the responsiveness of the maternal rat brain to pup‐suckling under various experimental paradigms. Our research employing the lactating rat model has explored the cortical sensory processing of pup stimuli and the effect of suckling on the brain’s reward system. Suckling was observed to increase blood‐oxygen‐level‐dependent (BOLD) signal intensity in the midbrain, striatum and prefrontal cortex, which are areas that receive prominent dopaminergic inputs. The BOLD activation of the reward system occurs in parallel with the activation of extensive cortical sensory areas. The observed regions include the olfactory cortex, auditory cortex and gustatory cortex, and could correspond to cortical representations of pup odours, vocalisations and taste that are active during lactation. Activation patterns within reward regions are consistent with past research on maternal motivation and we explore the possibility that exposure to drugs of abuse might be disruptive of maternal neural responses to pups, particularly in the prefrontal cortex. Our ongoing fMRI studies support and extend past research on the maternal rat brain and its functional neurocircuitry.

Functional, anatomical, and neurochemical differentiation of medial preoptic area subregions in relation to maternal behavior in the mouse

“…Non-maternal animals, such as fathers or any older conspecific animals, might provide maternal-like care to the young using behaviors collectively designated as parental behavior. Although several brain areas are important for different parental behavior components (Febo, 2011;Pereira and Morrell, 2011;Stolzenberg and Numan, 2011), the medial preoptic area (MPOA) has been shown to be the most critical, especially for pup retrieval, as shown by the following four lines of evidence: first, destruction of MPOA with either electrical or excitotoxic lesions disrupts both established maternal behavior in postpartum females (Numan, 1974;Jacobson et al, 1980;Numan et al, 1988) and the onset of parental behavior in adult females (Numan et al, 1977;Fleming et al, 1983), adult males, and juveniles (Rosenblatt et al, 1996;Sturgis and Bridges, 1997;Kalinichev et al, 2000;Oxley and Fleming, 2000;Lee and Brown, 2002). Knife cuts of dorsolateral connections of the MPOA also abolish the maternal behavior of postpartum rats (Terkel et al, 1979;Numan and Callahan, 1980;Numan et al, 1990) and hamsters (Miceli and Malsbury, 1982).…”

Firing patterns of maternal rat prelimbic neurons during spontaneous contact with pups

“…Delayed response cells have been described in working memory tasks in the rat. Information processed during such a firing pattern is perhaps incorporated into working memory (Jung et al, 1998) or conveyed to other subcortical areas such as the dorsal striatum (Febo, 2011). Other work has shown that delayed response neurons fire when a sequence of stimuli predictive of a reward are presented (Cowen and McNaughton, 2007).…”

Genetic and neuroendocrine regulation of the postpartum brain

“…Offspring are highly rewarding and previous studies have demonstrated alterations in reward systems in the maternal brain (Wilsoncroft, 1968; Hauser and Gandelman, 1985; Lee et al, 1999; Mattson et al, 2001, 2003; Febo et al, 2005; Ferris et al, 2005; Mattson and Morrell, 2005; Seip and Morrell, 2007; Noriuchi et al, 2008; Strathearn et al, 2008; Febo, 2011). For example, naïve prepartum female rodents find social interactions with mouse pups to have low valence (Lonstein and De Vries, 2000), but postpartum females find social interactions with pups to be intensely rewarding (Hauser and Gandelman, 1985).…”