Cellular and Integrative Physiology

Erica Littlejohn, Ph.D.

Postdoctoral Fellow


Dr. Littlejohn is interested in harnessing endogenous repair mechanisms to reduce the burden of disease(s) caused by dysregulation of the central nervous system. Dr. Littlejohn completed her dissertation in May 2018 at the University of Kentucky. She investigated cellular and molecular mechanisms underlying neural plasticity in the hippocampus influencing recovery from traumatic brain injury.

Dr. Littlejohn joined the lab of Dr. Carie Boychuk in August 2018. Her training in Dr. Boychuk’s lab will equip her to use sophisticated electrophysiological techniques to investigate the functional consequences of neural plasticity in the CNS. Parasympathetic drive is critical to the maintenance of whole-body homeostasis and normal physiological organ function.  In states of energy homeostatic dysfunction, like obesity, parasympathetic drive is reduced. Parasympathetic output is generated through motor neurons localized in the brain stem whose axons course through the vagus nerve. The set of these preganglionic motor neurons originating in the dorsal motor nucleus of the vagus (DMV) are implicated in diabetic parasympathetic dysregulation since DMV neurons send axonal projections to nearly all subdiaphragmatic viscera important in metabolism. Dr. Boychuk recently showed that in models of energy homeostatic dysfunction like chronic hyperglycemia/hypoinsulinemia, DMV neurons demonstrate significant plasticity, particularly in GABAA receptor function. However, the mechanism of this functional upregulation are currently unknown, making targetable treatment options difficult to assess. One potential target is a secondary, endogenous ligand to the GABA receptor, the neurosteroid derivative of progesterone, allopregnanolone. Interestingly, allopregnanolone has been implicated in estrous cycle modulation of GABAA receptor function as well, making it critically important to understand how these currents work in female, both in health and disease. In Dr. Boychuk’s lab, Dr. Littlejohn will employ obesity models, and to a larger extent diabetes models to investigate the role neurosteroids play in hyperglycemia after high-fat diet on GABAergic regulation of the DMV and glucose metabolism in females.