Visual evoked response (VER) changes during maturation in the Weddell seal

Area of Science:

• Marine Mammal Physiology
• Neuroscience
• Developmental Biology

Background:

• Visual evoked responses (VERs) provide insights into visual pathway maturation.
• Immature Weddell seals offer a model for studying early visual development in marine mammals.

Purpose of the Study:

• To characterize the developmental trajectory of visual evoked responses in immature Weddell seals.
• To correlate VER changes with age and key behavioral milestones.

Main Methods:

• Recording of cortical VERs from Weddell seals aged 3-365 days.
• Utilizing different anesthetic/paralytic agents (CI-744 vs. flaxedil) to assess their impact on VER recordings.
• Analyzing VER onset latency, waveform configuration, and topographical distribution.

Main Results:

• High degree of visual cortex maturity observed at birth, indicated by multiphasic waveforms and short onset latency.
• Developmental sequence of VERs was clearly observed in CI-744 dosed seals, unlike flaxedilized seals.
• VER changes, including latency and waveform, occurred with age and were linked to behavioral events like first swimming and weaning.

Conclusions:

• The visual system of Weddell seals is remarkably mature at birth.
• VER analysis provides a sensitive measure of visual pathway development in early life.
• Key behavioral events in early development are associated with distinct changes in visual evoked responses.