The Man Who Wasn't There: Investigations into the Strange New Science of the Self (31 page)

As we have already seen, the brain takes care of the body by maintaining homeostasis, which involves keeping the body’s physiology at an optimal state despite wide variations in the external environment. It was a detailed examination of one of the neural pathways involved in homeostasis—having to do with thermal regulation—that led Craig to the anterior insula.

In his talk in Sweden, Craig mentioned a paradox that had bothered him when he was a graduate student in the 1970s. The neuroscience textbooks he was reading talked about how pain and temperature are represented in the somatosensory cortex, the part of the brain responsible for the sense of touch. As we saw in chapter 3, the somatosensory cortex was mapped out in the mid-twentieth century by Wilder Penfield, and showed the relationship between cortical areas and the tactile sensations in various parts of the body: stimulating a specific part of the somatosensory cortex would cause in the subject a feeling of being touched in a specific part of the body. But not so for pain or temperature. “Stimulation of the somatosensory cortex almost never causes pain or a feeling of temperature, and a lesion of the somatosensory cortex almost never affects pain or temperature,” Craig said in his talk. “I didn’t understand why textbooks would contain a contradiction like this. Of course, I passed all my tests by saying this is the way it is.” The question remained: where in the brain was the region dealing with pain and temperature?

As a neuroanatomist, Craig grappled with this problem. There were clues. To start with, there’s a curious illusion, a staple of science museums worldwide, called the thermal grill (discovered in 1896 by a Swedish physician). The grill, as the name suggests, is a set of metal
bars, alternately warm or cool. Neither the warmth nor the coolness is above the threshold of what’s considered hot or cold enough to cause pain. However, place your hand on this grill and you’ll likely experience a burning pain. “
The thermal grill reveals a fundamental feature of the organization of the nervous system—in this case, a fundamental interaction between the feelings of pain and temperature,” writes Craig.

In the mid-1990s, Craig and his colleagues used PET scans to study the brains of people while they were experiencing the burning pain induced by the thermal-grill illusion. The subjects were also studied when they touched the warm and cold parts of the grill one at a time, which resulted in no pain. Their findings were revelatory:
the experience of pain was correlated with activity in the anterior cingulate cortex (ACC), whereas the mid-to-anterior insula was activated at all times (whether the thermal stimuli were painful or not).

In his subsequent studies also using PET scans, Craig showed that the posterior insula is responsible for representing temperature objectively, but the activity in the anterior insula was correlated not with the objective temperature but with the subjective perception of it. This is an interesting and crucial difference. Say you drink a glass of cold water. Seen from the perspective of Craig’s results, the posterior insula is representing the actual temperature of the water, but depending on whether you drink the water on a hot day or an icy-cold day, your subjective feelings about the glass of water will differ—possibly from an extremely pleasant sensation to something that is undesirable. This subjective feeling is what’s being represented in the anterior insula. And his work on the thermal-grill illusion suggested that when the sensation goes from being merely pleasant or unpleasant to thermal distress (something that the body has to act upon), then both the anterior insula and the anterior cingulate cortex are activated.

This has led Craig to argue that a feeling is more than just a perception of a body state; it also includes the motivation to do something about it. As Craig puts it, “
Activation of the ACC is associated with motivation, and activation of the insula is associated with feeling, which together form an emotion.” And the emotion drives homeostasis—if being out in cold weather becomes painful, the pain drives the organism toward seeking warmth.

And so it was that the study of pain and temperature led Craig to the insula, and his idea that this deep-brain region is crucial for self-awareness. A body of work is now showing that the anterior insula and anterior cingulate cortex are activated by a whole host of feelings, from anger to lust, from hunger to thirst. Craig rolled his work and that of others into a compelling hypothesis. He argued that the anterior insula is the brain region responsible for our feelings—the neural substrate for the subjective awareness of our body’s physiological state. It involves the integration of external sensations, internal sensations, and states representing the body’s motivation for action. “
It seems to provide the anatomical basis for emotional awareness.”

Craig argues that the anterior insula provides the grounding for the “material me” or the self-as-object, creating the moment-to-moment mental image of “
the material self as a feeling (sentient) entity.” And since much of the material self is based on an unchanging body (at least on short timescales), it could be the “
source of the sense of continuous being that anchors the mental self.” As Craig told me during a phone interview, “The immediate self, present in this moment, is based in the anterior insula.”

It was these studies that led Picard to her hypothesis that the anterior insula could be the focus of ecstatic seizures. Were such seizures intensifying the experience of being the material me, the self as
experienced here and now? The best evidence for her idea came when Fabrice Bartolomei emailed her saying that they had induced feelings associated with ecstatic seizures by stimulating a patient’s anterior insula directly.

Fabrice Bartolomei’s patient was a twenty-three-year-old woman. She first came to see Bartolomei along with her boyfriend, who was curiously suspicious of Bartolomei. “There was tension during the consultation,” Bartolomei told me during our phone conversation. Still, he examined the woman. She had started having seizures at fifteen, and stopped going to school as a result. She had a difficult personality, with aggressive, sociopathic tendencies. She was oppositional and moody during the consultations; her boyfriend came along to most of them at her insistence, and his negativity didn’t help matters either. Despite all this, her symptoms had a silver lining. Her seizures always began with moments of ecstasy—much like Prince Myshkin’s—before the seizures eventually knocked her unconscious.

“[Given] the mood of the patient was not very good, I was a bit surprised that the beginning of the seizures could [induce a] sensation of floating, with a strong shivering,” said Bartolomei. The patient reported feeling happy during the ecstatic aura at the start of her seizures. “There was a sort of contrast between the sensations during the seizure onset and the general behavior of the patient.”

The young woman had come to see Bartolomei because her epilepsy was resistant to drugs, and scalp EEG was not enough to locate the origin of her seizures. Bartolomei decided to insert depth electrodes into the patient’s brain, to record brain activity during seizures and home in on the epileptogenic tissue, which could then be
surgically excised. Bartolomei’s measurements suggested that the seizure first began in the temporal lobe but quickly spread to the anterior insula in less than one second—supporting the idea that this region was triggering the blissful feelings at the beginning of the seizure.

When Bartolomei used the same electrodes to stimulate his patient’s brain in specific places, one by one, the patient initially turned aggressive—she was reacting to the procedure, which Bartolomei accepts can be difficult for patients. This makes the following sequence of events all the more remarkable. Of the first eight electrodes, only the one stimulating the amygdala induced a response—in this case an unpleasant feeling (in addition to the patient’s antagonism toward the procedure in general).
But when the electrode in the anterior insula was activated, things changed. “The first thing I saw was a change in the facial expression. She seemed to be more happy, and less in tension,” Bartolomei told me. The patient reported feelings that were akin to what she felt during her ecstatic auras. “I feel really well with a very pleasant funny sensation of floating and a sweet shiver in my arms,” she told the doctors. And the greater the intensity of the stimulation, the greater was the “funny sensation.” Bartolomei cautions that this is just one case, yet the evidence is strongly suggestive of the insula’s involvement in ecstatic seizures. “The only site where we obtained this kind of pleasant sensation was the anterior insula,” he told me. “We did not obtain this by the stimulation of the temporal pole, the amygdala, or the hippocampus.”

After the exploratory stimulations, Bartolomei suggested surgery to his patient to remove the epileptogenic tissue, but thus far she has decided against it. Nonetheless, this patient’s experiences have given Picard the much-needed “proof” for the role of the anterior insula in ecstatic seizures. Picard is more and more convinced that
hyperactivity in the anterior insula is causing these feelings of bliss, well-being, and heightened self-awareness.

Neuroscientist Anil Seth, the researcher from the University of Sussex who has hypothesized that the brain’s predictive mechanisms are involved not just in the perception of external stimuli but also of internal body states, is impressed by this work. “The fact that the direct electrical stimulation of the insula does elicit these kinds of feelings is pretty compelling,” he said. The evidence also is consistent with findings that show that the insula is underactive in people with depersonalization disorder, in which they “describe the world as being drained of sensory and perceptual reality,” said Seth. A hyperactive insula during ecstatic seizures produces the opposite effect.

“
One bright May morning, I swallowed four-tenths of a gram of mescalin dissolved in half a glass of water and sat down to wait for the results.” Thus began Aldous Huxley’s extraordinary adventure in the spring of 1953, documented in his book
The Doors of Perception.
Huxley took the drug mescaline under the supervision of psychiatrist Humphry Osmond (who reportedly did not “
relish the possibility, however remote, of finding a small but discreditable niche in literary history as the man who drove Aldous Huxley mad”). As it happened, Huxley did not go mad.

An arrangement of brightly hued flowers in a vase, which Huxley had found distasteful just hours before he popped the pill, had morphed in his perception. “
At breakfast that morning I had been struck by the lively dissonance of its colours. But that was no longer the point. I was not looking now at an unusual flower arrangement. I was seeing what Adam had seen on the morning of his creation—the miracle, moment
by moment, of naked existence.” When asked if he found the bouquet agreeable or disagreeable, he replied it was neither. “It just is,” he said.

He found his perception of space and time altered. “
Space was still there; but it had lost its predominance. The mind was primarily concerned, not with measures and locations, but with being and meaning. And along with indifference to space there went an even more complete indifference to time. ‘There seems to be plenty of it,’ was all I would answer, when the investigator asked me to say what I felt about time. Plenty of it, but exactly how much was entirely irrelevant. . . . My actual experience had been, was still, of an indefinite duration or alternatively of a perpetual present.”

Osmond would go on to coin the term “psychedelic,” for the effect drugs such as mescaline, psilocybin, and LSD have on the mind (“
To fathom Hell or soar angelic, just take a pinch of psychedelic,” he would write to Huxley in response to a rhyme that Huxley had composed, as they attempted to describe the mind-bending nature of these drugs).

It’s not surprising that accounts such as Huxley’s and the descriptions of people having ecstatic seizures seem eerily similar.
Neuroimaging studies of people taking psychedelic drugs such as psilocybin have also shown hyperactivity in the insular cortex and the anterior cingulate cortex.
In one double-blind study of fifteen male subjects, researchers found that taking ayahuasca—a psychoactive tea used in shamanistic rituals in the Amazon—caused increased blood flow to the anterior insula, among other brain regions.