Frontal Brain Injury Reduces Sensitivity to Reward-Predictive Cues and Remodels the Nucleus Accumbens

Area of Science:

• Neuroscience
• Behavioral Neuroscience
• Neurobiology

Background:

• Traumatic brain injuries (TBIs) can lead to persistent secondary pathologies and psychiatric disorders.
• Functional reorganization of neural circuits post-TBI contributes to altered behavior and increased psychiatric risk.

Purpose of the Study:

• To investigate how frontal TBI affects behavioral responses to reward cues and decision-making.
• To explore the role of the nucleus accumbens (NAc) core in mediating these TBI-induced changes.
• To examine the subacute and chronic neurobiological alterations in the NAc following frontal TBI.

Main Methods:

• Frontal TBI induction in a rodent model.
• Pavlovian conditioning and decision-making tasks (gambling task).
• Optogenetics, electrophysiology, single nucleus RNA sequencing, immunohistochemistry, and in vivo calcium imaging of the NAc core.

Main Results:

• Frontal TBI impaired Pavlovian behavioral responses to reward-predicting cues and reduced cue motivation.
• TBI led to chronic decision-making deficits and altered NAc core function, including increased neuronal excitability and plasticity markers.
• Subacute TBI induced stress and inflammatory responses, while chronic TBI showed reduced NAc activity and cue-evoked responses.

Conclusions:

• Frontal TBI causes significant reorganization of the NAc, reducing the salience of environmental reward cues.
• Impaired outcome processing in TBI may contribute to psychiatric symptoms like impaired decision-making and impulsivity.
• The NAc's altered response to cues presents a potential therapeutic target for TBI-related psychiatric conditions.