Defining putative tertiary sulci in lateral prefrontal cortex in chimpanzees using human predictions

Area of Science:

• Comparative neuroanatomy
• Systems neuroscience
• Primate brain evolution

Background:

• Tertiary sulci, shallow cerebral cortex indentations, are largely human or hominoid specific.
• Lateral prefrontal cortex (LPFC) tertiary sulcal morphology is linked to human cognition.
• The presence of small, shallow LPFC sulci in non-human hominoids remains unexplored.

Purpose of the Study:

• To determine if small and shallow LPFC tertiary sulci can be identified in chimpanzee cortical surfaces.
• To compare LPFC tertiary sulcal patterns between humans and chimpanzees.

Main Methods:

• Utilized two freely available multimodal datasets.
• Applied human predictions of LPFC tertiary sulci to chimpanzee cortical surfaces.
• Analyzed the presence, consistency, and depth of specific sulci (pmfs, pimfs).

Main Results:

• 1-3 components of the posterior middle frontal sulcus (pmfs) were identifiable in most chimpanzee hemispheres.
• Paraintermediate frontal sulcus (pimfs) components were found in only two chimpanzee hemispheres.
• LPFC tertiary sulci were generally smaller and shallower in chimpanzees than in humans, with some hemispheric differences in pmfs depth.

Conclusions:

• Specific posterior middle frontal sulcus components are present in chimpanzees, suggesting some shared tertiary sulcal features with humans.
• The findings provide probabilistic predictions to aid future definitions of these sulci in comparative neuroanatomy studies.
• This research has implications for understanding the functional and cognitive roles of LPFC tertiary sulci across species.