Mark A. Rossi, PhD

Dr. Mark A. Rossi is an Assistant Professor in the Department of Psychiatry at Robert Wood Johnson Medical School. He received his B.A. in psychology from the University of Michigan-Dearborn in 2009. He received his Ph.D. in Psychology and Neuroscience from the systems and integrative neuroscience program at Duke University in 2015 in the lab of Henry Yin where he used in vivo electrophysiology and optogenetics to study how the basal ganglia regulate motivated behavior. He completed his postdoctoral training in neurobiology in 2021 with Garret Stuber at the University of North Carolina and then at the University of Washington where he used deep brain two-photon calcium imaging, slice electrophysiology, and single-cell sequencing to investigate how lateral hypothalamic circuits guide feeding and obesity. Dr. Rossi joined the faculty of the Child Health Institute of NJ in July 2021.

The Rossi laboratory studies how distributed neural circuits control feeding and motivation. The lab is particularly interested in how diet influences the function of hypothalamic circuitry and how it may be modified in obesity. We use a combination of deep brain two-photon calcium imaging, electrophysiology, and genetic tools to perturb and observe neural activity.

Our research has uncovered mechanisms by which subcortical neurocircuits integrate information about motivational state to guide feeding behavior. Central to this is the development of methods to allow longitudinal tracking of individual neurons in deep brain regions using multiphoton microscopy.

• Discovered mechanisms by which the basal ganglia regulate behavior based on motivational state
• Characterized cell types of the lateral hypothalamus and how obesity affects gene expression and function
• Demonstrated that reward and aversion are processed by divergent outputs from the lateral hypothalamus

The goal of the lab is to understand how distributed neural circuits regulate feeding and motivated behavior and how these processes are disrupted by external factors, such as diet. One critical hub for motivated behavior, including feeding, is the lateral hypothalamus. Our current work is aimed at dissecting the contributions of anatomically and molecularly defined neuron populations within the lateral hypothalamus to reward-guided behavior. Of particular interest is understanding the function of lateral hypothalamic glutamatergic neurons, which typically act as a brake on feeding behavior. In obesity, these cells become less effective at restraining feeding and may contribute to increased food intake and weight gain. We use deep-brain calcium imaging, electrophysiology, and viral tools to perturb and observe neural activity in vivo.

• Rossi MA, Basiri ML, Liu Y, Hashikawa Y, Hashikawa K, Fenno LE, Kim YS, Ramakrishnan C, Deisseroth K, Stuber GD (2021) Transcriptional and functional divergence in lateral hypothalamic glutamate neurons projecting to the lateral habenula and ventral tegmental area. Neuron, 109(23).

• Rossi MA, Basiri ML, McHenry JA, Kosyk O, Otis JM, van den Munkhof H, Bryois J, Hubel C, Breen G, Guo W, Bulik CM, Sullivan PF & Stuber GD (2019) Obesity remodels activity and transcriptional state of a lateral hypothalamic brake on feeding. Science, 364(6447).

• Rossi MA & Stuber GD (2018) Overlapping brain circuits for homeostatic and hedonic feeding. Cell Metabolism, 27(1).

• Rossi MA, Li H, Kim IH, Bartholomew RA, Gaidis E, Barter JW, Lu D, Kim N, Cai M, Soderling SH, Yin HH (2016). A GABAergic nigrotectal pathway for coordination of consummatory drinking. Nature Neuroscience. 19.

• Rossi MA & Yin HH (2015). Elevated dopamine alters consummatory pattern generation and increases behavioral variability during learning. Frontiers in Integrative Neuroscience, 9(37).