Cortical Afferents of Area 10 in Cebus Monkeys: Implications for the Evolution of the Frontal Pole

Cereb Cortex. 2019 Apr 1;29(4):1473-1495. doi: 10.1093/cercor/bhy044.

Abstract

Area 10, located in the frontal pole, is a unique specialization of the primate cortex. We studied the cortical connections of area 10 in the New World Cebus monkey, using injections of retrograde tracers in different parts of this area. We found that injections throughout area 10 labeled neurons in a consistent set of areas in the dorsolateral, ventrolateral, orbital, and medial parts of the frontal cortex, superior temporal association cortex, and posterior cingulate/retrosplenial region. However, sites on the midline surface of area 10 received more substantial projections from the temporal lobe, including clear auditory connections, whereas those in more lateral parts received >90% of their afferents from other frontal areas. This difference in anatomical connectivity reflects functional connectivity findings in the human brain. The pattern of connections in Cebus is very similar to that observed in the Old World macaque monkey, despite >40 million years of evolutionary separation, but lacks some of the connections reported in the more closely related but smaller marmoset monkey. These findings suggest that the clearer segregation observed in the human frontal pole reflects regional differences already present in early simian primates, and that overall brain mass influences the pattern of cortico-cortical connectivity.

Keywords: New World monkey; connections; frontopolar cortex; prefrontal cortex; superior temporal cortex.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Afferent Pathways / cytology
  • Animals
  • Biological Evolution*
  • Cebus
  • Female
  • Frontal Lobe / cytology*
  • Gyrus Cinguli / cytology
  • Male
  • Neuroanatomical Tract-Tracing Techniques
  • Neurons / cytology
  • Temporal Lobe / cytology