Increased age affects properties characterizing behavioral plasticity in freely behaving Aplysia

Area of Science:

• Neuroscience
• Marine Biology
• Animal Behavior

Background:

• In vitro studies in Aplysia suggest age alters the gill withdrawal reflex (GWR) more than gill respiratory pumping movements (GPM).
• A hypothesis posits that greater age-related effects correlate with higher pathway plasticity.
• This hypothesis requires validation in intact, freely behaving organisms.

Purpose of the Study:

• To investigate age-related plasticity of GWR and GPM in intact, freely behaving Aplysia.
• To compare the plasticity of GWR and GPM across different age groups (young, mature, old).
• To determine if in vitro findings on age and plasticity extend to whole-animal behavior.

Main Methods:

• Behavioral plasticity tests in freely behaving Aplysia across three age groups.
• Assessed graded responses, habituation, dishabituation, and cross-talk between GWR and GPM.
• Compared plasticity measures between GWR and GPM pathways.

Main Results:

• The GWR exhibited significant age-related alterations in habituation and graded responses, particularly in young and old animals.
• The GPM showed less plasticity and was largely unaffected by age, displaying only graded responses and habituation.
• Young Aplysia lacked habituation and dishabituation for GWR, while mature animals showed all tested plasticity properties.

Conclusions:

• Behavioral plasticity and age-induced changes are interconnected in freely behaving Aplysia.
• Findings support the hypothesis that pathways with greater age-related effects exhibit higher plasticity.
• The study validates in vitro observations regarding age and neural plasticity in a whole-animal context.