Variability of brain anatomy for three common mouse strains.

Area of Science:

• Neuroscience
• Comparative Anatomy
• Genetics

Background:

• Understanding brain structure morphology variability is crucial.
• Investigating genetic and strain-specific influences on neuroanatomy.

Purpose of the Study:

• To analyze anatomical variability in mouse brain structures across different strains.
• To determine the genetic basis of neuroanatomical differences.
• To assess if outbred strains exhibit greater variability than inbred strains.

Main Methods:

• Ex vivo magnetic resonance imaging (MRI) of three mouse strains (C57BL/6, 129S6, CD-1).
• Generalised Procrustes Analysis (GPA) to quantify anatomical surface variability.
• Principal Component Analysis (PCA) to identify major modes of variation and strain discrimination.

Main Results:

• Three distinct bilateral modes of anatomical variability were identified in the motor cortex, somatosensory cortex, retrosplenial cortex, and entorhinal cortex.
• Variability in motor and somatosensory cortex anatomy is primarily driven by genetic (strain) differences.
• Outbred CD-1 mice did not show significantly higher overall brain anatomy variability compared to inbred strains.
• The first two principal components accurately distinguished between the three mouse strains (91% accuracy).
• Correlations between principal components of individual brain structures suggest interdependent developmental trajectories.

Conclusions:

• Neuroanatomical strain differences are captured by a low-dimensional space, offering a powerful complement to traditional methods for detecting gene-related brain differences.
• The study challenges the assumption that outbred strains inherently exhibit greater neuroanatomical variability.
• The findings highlight the interplay between genetics, development, and potentially epigenetic factors in shaping brain morphology.