Hippocampal neurogenesis promotes effortful responding but does not regulate effort-based choice

Area of Science:

• Neuroscience
• Behavioral Science
• Stem Cell Biology

Background:

• Low motivation is a key symptom of depression.
• Hippocampal neurogenesis is linked to motivation, but its precise role in human-relevant behaviors is unclear.

Purpose of the Study:

• To investigate the specific role of adult hippocampal neurogenesis in regulating motivation and effort-based decision-making.
• To elucidate the neurobiological underpinnings of motivational deficits in depression.

Main Methods:

• Utilized the hGFAP-TK rat model to deplete actively dividing neural stem cells in the hippocampus.
• Employed an effort-discounting operant task to assess motivation and response vigor.
• Rats chose between smaller (2 pellets/1 press) and larger (4 pellets/2-20 presses) rewards.

Main Results:

• Depletion of adult neurogenesis did not alter general motivation or effort-based choice.
• A significant reduction in response rate was observed, increasing the time to obtain rewards.
• Lack of adult neurogenesis specifically impaired response vigor, not the willingness to exert effort.

Conclusions:

• Adult hippocampal neurogenesis plays a specific role in modulating response vigor for reward acquisition.
• Findings deepen the understanding of how neurogenesis influences depression-related motivational deficits.
• This research highlights a specific behavioral deficit linked to impaired neurogenesis relevant to depression.