Previous work with the Froemke Lab found that motherhood changes the auditory cortex through release of the hormone oxytocin so that mothers are more responsive to pup sounds and calls for help. In this aim, we are using specially designed mouse fMRI (created by collaborator Itamar Kahn) to evaluate which other brain regions are involved in auditory plasticity activated by parenthood. Prior work shows that mice that have not given birth can learn maternal behaviors through social examples, but how do changes in their brains compare to changes in the brains of parents? By investigating how parenthood itself changes the brain, we hope to understand which changes in the parental brain can be learned, and which are biologically activated by the process of producing offspring.

The Marlin Lab is also interested in understanding how parenthood changes the olfactory system. In this aim, we are investigating the changes that occur in the nose of rodent mothers before, during, and after pregnancy. We will also evaluate how changes in the mother’s nose compare to olfactory circuits in fathers and females who have not reproduced. Does the nose become more sensitive to the smell of a pup? If so, when does that change occur? Our goal is to understand how the olfactory circuit changes to prepare parents to take care of their offspring.

We are investigating precisely when and how learning changes the sensory circuits in the adult brain, focusing on the rodent olfactory system during fear conditioning. In these experiments, mice are exposed to a smell (e.g., almond scent) that is simultaneously paired with a mild foot shock. Over time, mice learn that the smell predicts the occurrence of shock, and if given the opportunity, will engage in escape-related behaviors to avoid the aversive stimulus. Our goal is to build a precise timeline of changes that occur in the olfactory circuit over the course of several weeks of fear learning to better understand how it is represented in the brain. We also evaluate the extent to which fear learning can alter the olfactory circuit before the circuit no longer responds to the stressor. Finally, we test which brain regions and signaling factors are necessary to detect the coincidence of a sensation (e.g., a specific smell) and an environmental stressor (e.g., a shock) and link them in the brain.

Revealing how and when changes occur in the adult brain provides a road map to investigate how changes are perpetuated in their offspring’s neural landscape. In this aim, we examine olfactory development and function in mice with or without a parental history of stress. As with the adult brain, one goal is to discover the extent to which offspring circuits can be modified by stress, whether it be their own or inherited. For example, if offspring of stressed parents are exposed to the same smell/shock combination, are stress-induced neural changes amplified? Furthermore, are stress-induced changes in offspring neural circuitry permanent, or can inherited stress be unlearned? Finally, we are investigating how long stress-induced neural changes persist from parent to offspring by assessing the olfactory circuits of successive litters of stressed parents.