Evolution of cognitive function via redeployment of brain areas

more complex and subtle structure, where activity in many (most) brain areas supports
multiple tasks in multiple cognitive domains. The difference between the standard
picture and the functional organization suggested by the redeployment hypothesis is
perhaps best illustrated by contrasting the lower middle panel with the lower right panel.
Rather than large areas of mono-chromatic cortex, what we see instead is a large array of
unique colors, indicating the relative contributions of each Brodmann area to supporting
tasks in a given cognitive domain.

However, this does not mean that the cortex is in any way randomly or holistically
organized; far from it. In fact, as is illustrated below, we can make (and support) some
specific predictions about the relations between cognitive functions and brain areas based
on the phylogenetic age of the function and the brain area.

But first we need to present the data on the “scatter” of brain areas supporting various
cognitive functions. The average minimum graph distance between the Brodmann areas
activated by each of the 135 tasks is 3.89 (SD 2.00). Broken down by task category, we
get attention 3.13 (SD 2.06), perception 3.71 (SD 1.98), imagery 3.97 (SD 1.75), and
language 4.82 (SD 1.76). Figure 2 represents the cortex as an adjacency graph, with an
attention task (Corbetta, et al, 1993) superimposed.

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