The corticostriatal junction: a crucial region for forebrain development and evolution

Area of Science:

• Neuroscience
• Evolutionary Biology
• Comparative Anatomy

Background:

• The telencephalon's pallium shows conserved structures across mammals and sauropsids (reptiles and birds).
• Qualitative differences exist in the lateral pallium, particularly the six-layered neocortex in mammals versus the dorsal ventricular ridge (DVR) in sauropsids.

Purpose of the Study:

• To investigate the developmental origins of distinct lateral pallial organizations in mammals and sauropsids.
• To propose a hypothesis linking neuronal precursor migration at the corticostriatal junction (CS) to evolutionary divergence.

Main Methods:

• Comparative analysis of brain development across mammalian and sauropsid lineages.
• Examination of neuronal precursor generation and migration patterns at the corticostriatal junction (CS) and surrounding germinal zones.
• Phylogenetic and embryological stage comparisons.

Main Results:

• The corticostriatal junction (CS) region generates distinct structures in mammals (neocortex, amygdala, claustrum-endopiriform formation) compared to sauropsids (dorsal ventricular ridge, DVR).
• Differences in the development and fate of neural populations originating from the CS region are proposed as a key factor in evolutionary divergence.
• The anterior part of the dorsal ventricular ridge (ADVR) in sauropsids receives specific thalamic input, contrasting with mammalian lateral pallial organization.

Conclusions:

• Evolutionary mutations affecting neural populations at the corticostriatal junction (CS) likely drove the divergence of mammalian and sauropsid pallial structures.
• Understanding these developmental differences is crucial for comprehending the evolution of complex cognitive functions associated with the neocortex.