The evolution of the cortico-cerebellar complex in primates: anatomical connections predict patterns of correlated evolution

Abstract

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Human frontal lobes are not relatively large

“…The third possibility invokes an alternative route to cognitive specialization; coordinated expansion of functionally and anatomically connected areas, potentially including both cortical and noncortical regions (15,37). Neocortex, cerebellum, and intermediate nuclei, for example, show closely correlated evolution in terms of both volume and neuron numbers, after controlling for variability in the size or neuron numbers of other brain regions (15,32,37,38), suggesting that selective expansion of cortico-cerebellar systems was a general feature of primate brain evolution.…”

A mosaic pattern characterizes the evolution of the avian brain

“…Several examples of this are provided in Rehkamper et al (2001) and include greater expansion of olfactory, spatial and somatosensory regions than of other brain regions. The 'mosaic theory' has been corroborated by multivariate analyses Whiting & Barton 2003), which demonstrate that not only do mosaic changes occur, but the relative proportions of brain regions are order-specific (Barton & Harvey 2000;de Winter & Oxnard 2001). That is, there are differences between orders and species in the structural organization of the brain and these are, in turn, representative of ecological differences.…”

“…However, brain regions do not evolve in isolation since they are interconnected with other regions as part of functional circuits and systems. In fact, comparative studies of neural systems indicate that correlated changes do occur between functionally connected regions (Barton et al 1995;Barton & Harvey 2000;Whiting & Barton 2003). Two opposing, but not exclusive, theories have been proposed to explain these correlated changes.…”

“…The second theory suggests that overall brain size can be increased by the expansion of specific brain regions independently of other regions (Barton & Harvey 2000;de Winter & Oxnard 2001;Rehkamper et al 2001;Barton et al 2003;Whiting & Barton 2003). Several examples of this are provided in Rehkamper et al (2001) and include greater expansion of olfactory, spatial and somatosensory regions than of other brain regions.…”

Functional mastery of percussive technology in nut-cracking and stone-flaking actions: experimental comparison and implications for the evolution of the human brain

“…The cerebrocerebellum is crucial for execution of prehensile upper limb movements, in both feed-forward and visual feedbackguided modes of regulation of ongoing movements in action execution. It works in conjunction with primary motor cortex and parietal association cortex (via the pontine nuclei) in the organization of skilled manual actions [103,109,111]. The cerebrocerebellum is also involved in a frontal cortical circuit (primarily prefrontal) via the basal ganglia, which is involved in novel motor sequence learning ('incremental acquisition of movements into a well-executed behaviour' [112, p. 252]).…”