Heterotopic interhemispheric cortical connections in the rat

Area of Science:

• Neuroscience
• Comparative Anatomy
• Brain Connectivity

Background:

• Previous research suggested limited heterotopic interhemispheric connections in rats.
• Interhemispheric pathways were thought to primarily link homotopical cortical regions.

Purpose of the Study:

• To investigate the extent and nature of interhemispheric cortical connections in the rat.
• To identify specific heterotopic connections between different cortical areas.

Main Methods:

• Iontophoretic injections of horseradish peroxidase (HPP) were used to trace neural pathways.
• Neural tracing was conducted in rat brains to map cortical connections.

Main Results:

• Extensive heterotopic interhemispheric connections were identified between posterior insular (perirhinal) and anterior prefrontal cortical regions.
• These reciprocal connections were observed in both directions (posterior insular to anterior prefrontal and vice versa).
• Connected areas also showed intrahemispheric connections, with contralateral projections being less than one-third of ipsilateral projections.

Conclusions:

• The rat brain exhibits more complex interhemispheric cortical connectivity than previously assumed.
• These findings highlight significant heterotopic connections, particularly between the insular and prefrontal cortices.
• The study revises the understanding of brain organization and interhemispheric communication in rodents.