Pereira and Morrell hypothesized that a brain region must direct a mother to prioritize offspring over drugs. Image is in the public domain.
Summary: The infralimbic system priorities caring for offspring and promotes maternal behavior in rats.
Motherhood takes over the brain’s decision-making regions to prioritize caring for offspring, according to new research in rats published in eNeuro.
Making decisions requires the medial prefrontal cortex filtering and repressing multiple streams of information. This often involves picking between powerful, conflicting stimuli, such as when drug-using mothers must choose between their new child or drug-seeking. Since the most effective addiction therapies in this situation work by emphasizing the mother/infant relationship, Pereira and Morrell hypothesized that a brain region must direct a mother to prioritize offspring over drugs.
To pinpoint this brain region, the team temporarily inactivated different regions of rats’ prefrontal cortices with a local anesthetic and tested the rats’ preference for their pups or cocaine. Before inactivation, 40% of rats preferred to spend time in a room associated with cocaine, 40% preferred a pup-associated room, and 20% preferred a neutral room.
But when the scientists inactivated the rats’ infralimbic cortex, 78% of rats preferred the cocaine room and none chose the pup room. The opposite was true when the prelimbic cortex was inactivated: 71% of rats preferred the pup room, and none chose the cocaine room. Inactivating the infralimbic cortex also decreased the mother’s maternal behaviors towards her pups. The researchers found that during motherhood, the brain recruits the discriminating powers of the infralimbic cortex to prioritize offspring over competing desires.
About this neuroscience research article
Source: SfN Media Contacts: Calli McMurray – SfN Image Source: The image is in the public domain.
Infralimbic Cortex Biases Preference Decision Making for Offspring Over Competing Cocaine Associated Stimuli in New Mother Rats
In the context of drug abuse, converging evidence suggests that cocaine use in new mothers is significantly reduced by the competing motivation related to child rearing. Given the demonstrated importance of the medial prefrontal cortex (mPFC) in decision making processes, we investigated the contribution of distinct regions of the mPFC (anterior cingulate, prelimbic, infralimbic) to decision-making in new mother rats performing a concurrent pup/cocaine choice conditioned place preference (CPP) task. When given a choice, inactivation of infralimbic cortex significantly biased decision-making of mother rats towards cocaine-associated cues, highly contrasting the distribution of preferences by control groups. In contrast, inactivation of prelimbic cortex had the opposite effect, significantly increasing offspring bias in the decision making, such that none of mothers chose the cocaine-associated alternative. Anterior cingulate inactivation was without effect. Functional inactivation of these same mPFC subregions had no effect in a non-conflict CPP task in which context-induced cocaine or pup seeking were examined separately. Notably, inactivation of the infralimbic cortex also interfered with maternal behavior. Taken together, we have identified a specific role of the infralimbic cortex in the prioritization of offspring over drug competing alternatives, thus promoting resistance to drug use in new mothers.
Cocaine use by postpartum women is a serious health problem that has a tragic impact on the mother’s ability to properly care for her child, with life-long consequences for both the mother and her child. Here we show that in the context of new motherhood, the infralimbic cortex biases decision making toward offspring stimuli over cocaine seeking in new mothers. These findings provide novel information about how the maternal brain processes information about offspring and how this information is integrated to bias decision-making. Considering the major impact of maternal cocaine use on both mother and child health, understanding how maternal motivation can provide resistance to drug use is highly pertinent.