Robert J. Marks and I submitted a paper to a philosophy journal in which we made two key points: Christof Koch’s Integrated Information Theory (IIT) is not an adequate theory of consciousness. Secondly, the human intellect and will are immaterial. The paper is still under review and we have received a number of reviewer questions. What follows is the gist of a response to one of them. – Michael Egnor

Public Domain photo from United States National Library of Medicine via Wikipedia Commons.

A reader who has a background in neuroscience and philosophy has been critical of my citation of the research of neurosurgeon and neuroscientist Wilder Penfield (1891–1976). Penfield’s research demonstrates that the intellect and will are immaterial powers of the human soul and are not generated by the brain. He found that stimulation by an electrical probe of the brain cortex of awake patients undergoing brain surgery never elicits abstract thought or the illusion of free will.

The reader writes:

Every task involves activation in a network of multiple local brain areas. The idea that one could activate such networks through stimulation with a single electrode is little short of absurd, although the possible existence of specific local network trigger points is suggested by the fact that Penfield could stimulate complex memories in only about 5% of cases.

I reply:

The lasting importance of Penfield’s work is underestimated. I’ve performed awake brain surgery, and I understand the logistics of such procedures. Penfield performed 1100 awake brain operations, each lasting roughly 8 hours, consisting of roughly 2 stimulations per minute, which is almost 1000 stimulations per patient and 1,100,000 stimulations over his career.

Not a single one of his 1.1 million brain stimulations in awake patients evoked what he called “mind action”, by which he meant abstract thought. How many brain stimulations that do not evoke abstract thought are necessary before we can draw the scientific inference that abstract thought does not come from the brain?

What did Penfield find?

After 1.1 million individual brain stimulations in awake patients, he found that he could stimulate four and only four responses: movement, perception, emotion and memory. His vast experience with systematic direct stimulation of the brain in conscious subjects is unparalleled in neuroscience and is obviously of immeasurably greater scientific importance than a handful of fMRI studies with abysmal temporal and spatial resolution that do not directly image neuronal activation.

Penfield concluded as a result of his stimulation attempts that neither the intellect nor the will is generated by the brain. Such massive evidence generated by over a million stimulations of the living human brain in a controlled scientific setting is as close to decisive as it gets in neuroscience and cannot be dismissed.

The reader points out that Penfield was able to stimulate complex memories in 5% of cases, which — over his surgical career — is 55,000 brain stimulations that “activated complex networks with a single electrode.” Not one of these 55,000 brain stimulations generated abstract thought. So, even if brain stimulation fails to activate complex networks 95% of the time, the 5% that do activate them represent 55,000 individual activations without a single one that involved abstract thought.

How much more evidence is necessary to draw the scientific inference that activation of brain networks is insufficient to generate abstract thought?