The development of the jamming avoidance response in the weakly electric fish, Eigenmannia

Area of Science:

• Neuroscience
• Animal Behavior
• Sensory Biology

Background:

• The jamming avoidance response (JAR) is crucial for weakly electric fish, Eigenmannia, relying on a functional electrosensory phase-coding system.
• Fish size is the primary predictor for the onset of the JAR, indicating developmental stages.

Purpose of the Study:

• To investigate the developmental timeline and underlying neural mechanisms of the jamming avoidance response (JAR) in young Eigenmannia.
• To determine the relationship between fish size, electrosensory system maturation, and JAR performance.

Main Methods:

• Monitoring JAR development in Eigenmannia correlated with fish length (head to tail).
• Observing JAR performance in fish raised in isolation to assess social interaction dependency.
• Examining anatomical changes in the torus semicircularis, specifically giant cells and the commissural plexus, in relation to JAR strength.

Main Results:

• A distinct JAR (≥0.15 Hz) emerges at 12-15 mm length, strengthening to adult levels (8-20 Hz) by ~45 mm.
• JAR performance is independent of social interactions, demonstrated by isolated fish.
• Increased JAR strength correlates with more giant cells and a developed commissural plexus in lamina 6 of the torus semicircularis.

Conclusions:

• Fish size is a reliable indicator for the developmental onset and maturation of the JAR.
• The development of the JAR is intrinsically linked to the maturation of the electrosensory phase-coding system, particularly lamina 6 of the torus semicircularis.
• Neural correlates, including giant cells and the commissural plexus, underpin the JAR's development and function in Eigenmannia.