Telencephalic neural activation following passive avoidance learning in a terrestrial toad.

Area of Science:

• Neuroscience
• Animal Behavior
• Comparative Psychology

Background:

• Passive avoidance learning is crucial for survival across species.
• Understanding the neural mechanisms of learning in amphibians provides insights into vertebrate brain evolution.

Purpose of the Study:

• To investigate the neural basis of passive avoidance learning in toads (Rhinella arenarum).
• To identify specific brain regions involved in this learning process.

Main Methods:

• Experiment 1: Toads were trained using a two-compartment box with a mild stressor (hypertonic NaCl solution) to elicit passive avoidance.
• Experiment 2: Neural activation in five brain regions was assessed using AgNOR staining after passive avoidance learning.

Main Results:

• Toads exposed to a hypertonic NaCl solution showed a significant increase in latency to enter the dark compartment, indicating passive avoidance learning.
• This learned avoidance was gradually acquired and extinguished.
• Higher neural activation was observed in the amygdala and striatum of toads that learned passive avoidance.

Conclusions:

• The study suggests a striatal-amygdala circuit is involved in passive avoidance learning in amphibians.
• These findings contribute to understanding the evolution of learning and memory circuits in vertebrates.