Network structure of functional hippocampal lateralization in birds

Area of Science:

• Neuroscience
• Comparative Neuroanatomy
• Avian Cognition

Background:

• Functional hemispheric asymmetry is prevalent in vertebrates, but neural mechanisms of dominance are unclear.
• The left avian hippocampus is crucial for navigational processes, particularly homing in pigeons.
• Understanding hemispheric specialization provides insights into brain organization and function.

Purpose of the Study:

• To investigate the neural basis of left hippocampal dominance in avian navigation.
• To compare functional connectivity patterns between left and right hippocampi in birds.
• To determine if broader functional connectivity underlies left hippocampal functional dominance.

Main Methods:

• Resting-state functional magnetic resonance imaging (fMRI) was employed in homing pigeons and starlings.
• Functional connectivity (FC) was assessed by seeding analysis within the hippocampal formation.
• FC maps were generated and compared based on seeding in either the left or right hippocampus.

Main Results:

• Seeding the left hippocampus consistently produced larger functional connectivity (FC) maps compared to the right.
• Left hippocampal seeding more frequently resulted in FC extending to the contralateral hippocampus.
• FC maps from left hippocampal seeds often extended beyond hippocampal boundaries.

Conclusions:

• Broader functional connectivity is a key neural property conferring functional dominance to the left hippocampus in birds.
• This finding supports the hypothesis that enhanced network engagement underlies left hippocampal specialization for navigation.
• The study elucidates a neural mechanism for hemispheric asymmetry in a critical cognitive function.