The Location of the "Executive"

One intriguing finding from brain scanning research is that a brain area called the anterior cingulate gyrus in the frontal lobes, slightly above the level of the eyes, lights up with activity when subjects perform active, intentional information processing of any type (Posner, 1993). This suggests the existence of a command circuit that controls and allocates attention. Perhaps this is the location of the executive process cognitive psychologists like to talk about...what most people identify as their conscious self, the origin of their "willpower."

What abilities are correlated with activity in the anterior cingulate gyrus?

Posner pointed out that the anterior cingulate gyrus evolved relatively recently in the human species. It allows comprehensive forward planning in the human species. Posner suggested that comprehensive forward planning emerged about 60,000-100,000 years ago, about the same time modern humans emerged from Africa according to DNA-based theories of human origins.

Nicely crafted stone tools have been found in China and Africa dating to about 800,000 years before the present. The fabrication of tools implies an ability to plan for the future, so the ability to plan evidently emerged gradually in our pre-modern ancestors such as homo erectus, then it grew more sophisticated with time.

What is evidence that Neanderthal's lacked comprehensive planning abilities?

What Posner calls comprehensive forward planning ability is something more than fashioning a stone tool, however. Neanderthals could make stone tools, but they never put them on axe handles. They never built shelters out of durable materials, unlike modern human ancestors who lived at the same time as the Neanderthals. Some Neanderthals lived near the Mediterranean, but there is no evidence they ever built boats.

What changes occurred when modern humans appeared?

Something special happened about 60-100,000 years ago, leading to modern humans. Homo erectus, a pre-modern primate ancestral to both Neanderthals and modern humans, was first to travel out of Africa to far corners of the world. Homo erectus had both fire and simple stone tools, but homo erectus did not innovate. The basic tool (the hand axe) remained unchanged for hundreds of thousands of years. When anatomically modern humans appeared, there was a new, larger prefrontal cortex as well as an explosion of creativity and art.

What happens when the prefrontal area is damaged?

When humans suffer damage to the prefrontal cortex, they lose the ability to engage in creative work, as described in Chapter 2. They become "stimulus bound," reacting to their immediate surroundings, neglectful of long-term plans. Perhaps the anterior cingulate gyrus is required for the detailed planning and sustained acts of creativity so important to our species.

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Copyright © 2007 Russ Dewey