Research Interests
Our research program is focused on understanding biological and behavioral factors governing psychiatric-related dysfunction and developing interventions to address these impairments.
A large portion of our research involves the study of traumatic brain injury (TBI) because of the significant health burden resulting from behavioral dysfunction after injury. We make use of behavioral assessments in rats directly adapted from neuropsychiatry or neuropsychology to have the most “human-like” animal model we can with respect to behavior. The idea is that this will facilitate translation of treatment findings to the human population.
A strong secondary focus of the laboratory is refining methodology to improve rigor in science. We do this in a variety of ways, ranging from evaluating statistical methodology to developing novel devices for behavioral testing in species such as pigs.
Disrupted Processing of Reward Outcomes after TBI
TBI shifts decision-making from an optimal phenotype to suboptimal and risky phenotypes (A; from Vonder Haar et al., 2022). TBI decreases willingness to exert effort for a visual cue previously associated with rewards (B; adapted from Modrak et al., 2020)
Brain injury causes widespread disruption to multiple circuits and neurotransmitter systems. Of particular relevance is substantial evidence that dopamine signaling is impaired. This directly affects circuits involved in the processing of both beneficial (“reinforcing”) and detrimental (“punishing”) outcomes. Our research explores this fundamental change in to better understand how we might intervene via pharmacological, behavioral, or other treatments.
Research in this area has been funded by the National Institutes for Health (R01-NS110905; Dr. Vonder Haar) and the International Center for Responsible Gaming (Dr. Vonder Haar).
Neuroinflammatory Contributions to post-TBI Dysfunction
Motor impulsivity (measured as percent of premature responses) persists chronically after TBI and is graded by injury severity (A). Measurement of inflammatory cytokines alongside degree of damage is strongly correlated to levels of impulsivity. Adapted from Vonder Haar et al., 2016.
The neuroinflammatory response to TBI is one of the most pervasive types of pathology, lasting for years after the initial injury. Multiple studies support a correlative link between persistent neuroinflammation and cognitive and psychiatric deficits. However, causal mechanisms for this remain unclear. Our current research investigates whether there are causal links between this pervasive pathology and the chronic deficits we observe in animal models of TBI.
Research in this area has been funded by the Department of Defense (HT9425-23-1-1003; Dr. Vonder Haar).
Neural Circuits of Impulsive Decision-Making
A behavioral intervention increases preference for self-controlled choices (Larger-Later, LL; panel A) across multiple Smaller-Sooner (SS) delays compared to pre-intervention baseline and a control group. This intervention specifically increased timing precision (higher peaks; panel B).
The principal focus of this research is to determine the neurobehavioral variations associated with environmental and experiential factors that cause impulsive decision making. We are evaluating neuroplastic changes to circuits involved in decision-making and timing following a learning-based behavioral intervention. Chemogenetic methods are used to manipulate key circuits that underlie the intervention’s effects to better understand their contributions. An additional project is investigating how high-fat diets increase impulsive decision-making and potential mechanisms (e.g., neuroinflammation, gut microbiome dysbiosis) that may explain the effects of diet on choice.
Research in this area has been funded by the National Institutes for Health (R01-MH085739; Dr. Smith).
The Role of the Gut Microbiome in Brain Injury
Unpublished data demonstrating changes in the abundance and variety of bacterial species (“diversity”; panel A-B) after TBI. These changes are reflected by alterations to multiple bacterial phyla (C).
The gut microbiome is a population of bacteria that influences brain function by modulating the vagus nerve, producing precursors to neurotransmitters, and generating immune response. TBI disrupts this function which may then feed forward and worsen the development of pathology and functional impairments. Our lab is interested in understanding how this happens and what treatments might be applied to mitigate these effects.
Research in this area has been funded by the Department of Defense (HT9425-23-1-0538; Dr. Martens).
Methodology Development and Evaluation
Demonstration of a pig working on a touchscreen for fruit-flavored pellets. A printed circuit board interfaces peripheral elements with a Raspberry Pi controlling the touchscreen.
Improving methodology is key to scientific advancement. Our lab is interested in multiple avenues to improve scientific research. We have published research helping identify key improvements that could be made to statistical analyses as well as developing tools for assessing cognitive function in pigs.