Human brain vs Apes | Brodmann area 10 | Differences

The cortex is divided into several cytoarchitecturally defined areas called 'Brodmann areas'. Cytoarchitecture refers to the cellular composition of the area.

BA10 (Brodmann area 10) is in the prefrontal part of the cortex. BA10 is the largest cytoarchitectonic (cytoarchitectonics, is the study of the cellular composition of the body's tissues under the microscope) area in the human brain.

The volume of the human BA10 is about 14 cm³ and constitutes roughly 1.2% of total brain volume. This is twice what would be expected in a hominoid with a human-sized brain. By comparison, the volume of BA10 in bonobos is about 2.8 cm³, and makes up only 0.74% of its brain volume. In each hemisphere, area 10 contains an estimated 250 million neurons.

Area 10 in humans has the lowest neuron density among primate brains.^[3] It is also unusual in that its neurons have particularly extensive dendritic arborization and are highly dense with dendritic spines.

Research upon primates suggests that area 10 has inputs and output connections with other higher-order association cortex areas particularly in the prefrontal cortex while having few with primary sensory or motor areas.

Katerina Semendeferi and colleagues has suggested that "During hominid evolution, area 10 underwent a couple of .. changes: one involves a considerable increase in overall size, and the other involves a specific increase in connectivity, especially with other higher-order association areas.

Area 10 forms the frontal pole of chimpanzee, orangutan, gibbon and bonabo brains. Aspects of its organization vary across species - relative width of layers, and space available for connections. Area 10 forms a bigger proportion of the cortex in humans than in other mentioned species. This suggests that tis part got enlarged during evolution.

Humans vs Apes | Morphology of pyramidal neurons in cortex

Dendritic Morphology of Pyramidal Neurons in the Chimpanzee Neocortex: Regional Specializations and Comparison to Humans (Cerebral Cortex - 2013)

Abstract: The primate cerebral cortex is characterized by regional variation in the structure of pyramidal neurons, with more complex dendritic arbors and greater spine density observed in prefrontal compared with sensory and motor cortices. Although there are several investigations in humans and other primates, virtually nothing is known about regional variation in the morphology of pyramidal neurons in the cerebral cortex of great apes, humans' closest living relatives. The current study uses the rapid Golgi stain to quantify the dendritic structure of layer III pyramidal neurons in 4 areas of the chimpanzee cerebral cortex: Primary somatosensory (area 3b), primary motor (area 4), prestriate visual (area 18), and prefrontal (area 10) cortex. Consistent with previous studies in humans and macaque monkeys, pyramidal neurons in the prefrontal cortex of chimpanzees exhibit greater dendritic complexity than those in other cortical regions, suggesting that prefrontal cortical evolution in primates is characterized by increased potential for integrative connectivity. Compared with chimpanzees, the pyramidal neurons of humans had significantly longer and more branched dendritic arbors in all cortical regions.

My comments: 
This work reports on a qualitative similarity and a qualitative dis-similarity in humans and apes pyramidal neurons of cerebral cortex.

Structure of pyramid neurons have a variation across different regions in humans as well as apes. More specifically (as found in this work) prefrontal cortex have greater dendritic complexity compared to other cortical regions.

However, humans have longer and more branched dendritic arbor.