Geschwind's theory of cerebral lateralization: developing a formal, causal model

Area of Science:

• Neuroscience
• Developmental Psychology
• Immunology

Background:

• The influential Geschwind-Galaburda model links fetal testosterone to neural, immune, and neural crest development.
• This model offers explanations for cerebral lateralization, learning disorders, giftedness, and immune deficits.

Purpose of the Study:

• To clarify the structure of the Geschwind-Galaburda model by presenting it as a causal-path model.
• To evaluate the internal coherence of the model, focusing on anomalous dominance, timing, and nonlinear processes.
• To consider the challenges in testing grand theoretical models and derive principles for assessing testability.

Main Methods:

• Causal-path modeling to structure the theory.
• Conceptual analysis to evaluate internal coherence.
• Discussion of methodological constraints for empirical testing.

Main Results:

• The article presents a structured causal-path representation of the Geschwind-Galaburda model.
• An evaluation of the model's coherence is provided, addressing key concepts and processes.
• Principles for assessing the testability of the model's predictions are derived.

Conclusions:

• The structured model enhances understanding of the Geschwind-Galaburda theory.
• Assessing the model's coherence and testability is crucial for its scientific advancement.
• Practical constraints like sample size and measurement error significantly impact empirical validation.