A ventral hippocampus to nucleus accumbens pathway regulates impulsivity

Area of Science:

• Neuroscience
• Behavioral Neuroscience
• Systems Neuroscience

Background:

• Heightened impulsivity is a core feature of substance abuse disorders, gambling, and obesity.
• The ventral hippocampus (vHPC) is implicated in impulse control, but its precise mechanisms remain unclear.
• A subset of vHPC neurons projects to the nucleus accumbens (ACB), a key area for reward and motivation.

Purpose of the Study:

• To investigate the role of vHPC-ACB signaling in regulating food-directed impulsivity.
• To elucidate the neurobiological mechanisms underlying impulse control mediated by the vHPC-ACB pathway.

Main Methods:

• Utilized fiber photometry to record neural activity in vHPC and ACB during a food-directed impulsivity task (DRL test) in rats.
• Employed chemogenetics to silence vHPC neurons projecting to the ACB in male and female rats.
• Used a novel transsynaptic viral strategy to selectively inhibit ACB neurons receiving vHPC input.

Main Results:

• Calcium-dependent activity in vHPC and ACB increased just before non-impulsive versus impulsive responses.
• Chemogenetic silencing of vHPC-ACB projections increased impulsive action in males but not females.
• Selective inhibition of vHPC-targeted ACB neurons elevated impulsive action in the DRL task.

Conclusions:

• A specific hippocampal-striatal circuit involving vHPC-ACB projections regulates impulsive action.
• This circuit plays a critical role in impulse control, particularly in males.
• Findings provide insights into the neurobiological basis of impulsivity and potential therapeutic targets.