An evolutionary interpretation of teleostean forebrain anatomy

Area of Science:

• Neuroscience
• Comparative Anatomy
• Evolutionary Biology

Background:

• Zebrafish (teleost fish) forebrain research reveals similarities to mammalian models like mice and rats.
• Gene expression patterns for neuronal phenotypes, including gamma-aminobutyric acid- (GABA-)ergic neurons, are conserved.
• Previous studies have identified homologies in subpallial and thalamic regions.

Purpose of the Study:

• To critically discuss and justify findings on zebrafish forebrain homologies.
• To propose a partial eversion model for teleost telencephalon development.
• To contextualize these findings within the broader scope of fish forebrain evolution.

Main Methods:

• Comparative analysis of molecular anatomy and gene expression patterns.
• Identification of homologous brain regions between zebrafish and mammals.
• Review and justification of proposed homologies, including the partial eversion model.

Main Results:

• Identified zebrafish subpallial regions homologous to mammalian medial and lateral ganglionic eminences.
• Established homologies for larval eminentia thalami and adult bed nucleus of the stria medullaris.
• Proposed homologies for all four mammalian pallial areas via the partial eversion model, with the posterior dorsal telencephalic area homologous to piriform cortex.

Conclusions:

• Zebrafish forebrain exhibits significant molecular and anatomical similarities to mammals, supporting conserved developmental pathways.
• The partial eversion model provides a framework for understanding teleost telencephalon organization and its homology to mammalian pallial areas.
• These findings contribute to a deeper understanding of vertebrate forebrain evolution, particularly in fishes.