To Penfield, it was clear that these unexpected responses he was getting by stimulating the medial temporal lobes differed fundamentally from the responses produced by stimulation of other parts of the brain. The response of his patients to the jolting of other areas might be marked by “a tingling feeling, an absence of feeling called numbness, a sense of movement; olfactory sensation, by a disagreeable odor; gustatory, by a strong taste,” but all of those sensations had one thing in common: They were generalized, not tied to any particular moment in time. The responses he was triggering by stimulating the medial temporal lobes were, Penfield noted, “of an entirely different order. They are made up of the acquired experience of that particular individual. It is the difference between a simple sound and a conversation or a symphony. It is the difference between the sight of colored squares and the moving spectacle of friends who walk and talk and laugh with you. The one is a simple element of sensation. The other is a recollective hallucination.”
A recollective hallucination.
In other words, a memory.
Penfield wrestled with the implications of what he’d observed. In his famous homunculus illustrations, he’d already mapped out the human brain’s sensory and somatosensory cortices. Now he’d stumbled into an entirely new domain: the memory cortex.
But how was this possible?
What made a spark of electricity spark the past?
“The answers to those questions are of great psychological importance,” Penfield wrote, before admitting that he was going to have to “venture from the firm ground of observation onto the dizzying scaffolding of hypothesis.” His patients’ experiences in the OR led him to believe that the human brain retained absolutely every experience that ever crossed its synapses. Every moment, every waking hour, even every dream. Anything that it had seen or heard or tasted or smelled or thought. Anything and everything, so long as during the moment of raw experience some attention had been paid to it. “Whenever a normal person is paying conscious attention to something,” Penfield wrote, “he is simultaneously recording it in the temporal cortex of each hemisphere. Every conscious aspect of the experience seems to be included in these records.” It was, as Penfield would later describe it to Time, as though there were a “tape recorder” in the brain, activated at the moment of birth and stopping only at death. Each event of a person’s life was stored away as a distinct “neurone pathway.” Even events that people might later have no ability to recall of their own volition, the ephemera of the everyday, were all carefully preserved. “It would appear,” Penfield said, “that the memory record continues intact even after the subject’s ability to recall it disappears.”
Penfield further speculated that when people engaged in an act of normal remembering, without the aid of an external electrode, they were still doing exactly what Penfield was doing to his patients on the operating table. That is, a self-generated electrical jolt to the medial temporal lobe’s “memory cortex” was triggering the playback of particular memories. “This would seem to be absurdly simple,” Penfield wrote, “and yet the new evidence is inescapable.”
—
Penfield first presented his theory of memory during his presidential address at the seventy-sixth annual meeting of the American Neurological Association on June 18, 1951. The meeting took place in the grand ballroom of the tallest building in New Jersey, the twenty-four-story Claridge Hotel, high above the boardwalk in Atlantic City. His presentation caused a stir. The first audience member to comment was Lawrence Kubie, a psychiatrist and psychoanalyst who had acquired a sort of reflected fame by gathering an impressive collection of famous clients, including Vladimir Horowitz and Tennessee Williams.
“I am profoundly grateful for this opportunity to discuss Dr. Penfield’s paper,” he said, describing how it had put him in a “state of ferment,” as though he were “watching pieces of a jigsaw puzzle fit into place and a picture emerge.” The address, he said, had “been as exciting a moment as I have spent in a scientific meeting in recent years. I can sense the shades of Harvey Cushing [the founder of modern neurosurgery] and Sigmund Freud shaking hands over this long-deferred meeting between psychoanalysis and modern neurology and neurosurgery, through the experimental work which Dr. Penfield has reported.”
Kubie then said that he hoped Penfield might begin adding dream studies and free association exercises to his battery of preoperative routines and wondered how many of the electrically stimulated memories might have been in fact the sorts of repressed memories that analysts such as himself trafficked in. Casting “a hopeful glance into the future,” Kubie imagined a day when even nonepileptics might have their brains “stimulated on the operating table” to “see whether the reliving of the past through electrical stimulation of the temporal cortex exercises any influence on preexisting neurotic symptoms and mechanisms, and on preexisting associative patterns and emotional storm centers”—a sort of open-brain psychoanalysis.
Penfield didn’t comment on Kubie’s suggestions, perhaps because he had always distrusted psychoanalysis and psychoanalysts. He was almost certainly pleased, however, by Kubie’s memorable summation of his discoveries.
“This is Proust on the operating table,” Kubie declared. “An electrical recherche aux temps perdu. Yet is it perdu?”
Others in the audience were less impressed.
A neurologist named Karl Lashley, who was at the time the world’s leading expert on the science of memory, was also in attendance. For the past two decades, working first at the University of Minnesota and then at his own laboratory in Orange Park, Florida, Lashley had conducted a series of experiments on rats, attempting to determine where their memories were stored. To do this, he would teach the rats a task, say, the proper way to navigate a maze, and then cut out various parts of their brains. What he found, to his surprise, was that no particular lesion would make the rats less able to remember how to navigate the maze. Instead the rat’s navigational skills became muddled in proportion to how much of their brain tissue he removed, regardless of where exactly he removed that tissue from. Also, he was able to teach the rats new tasks, regardless of what parts of their brains he removed. The conclusions he drew from this were that no particular part of the brain stored memories and, likewise, that no particular part of the brain was responsible for the task of storing memories. Instead, he theorized, when it came to memory, if you removed a specific part of the brain, the remaining parts would attempt to pick up the slack, taking over the tasks the lost part had once been responsible for. He called this theory equipotentiality, to indicate his belief that every part of the brain had equal potential. And equipotentiality, or replaceability, as others often referred to it, became the prevailing view of how memory worked. Looking for the specific sites responsible for memory creation and storage, in this view, was pointless, since those sites could be anywhere, changing from brain to brain.
In Atlantic City, Lashley’s critique of Penfield began somewhat obliquely, with a comment about the use of metaphor. This criticism was most likely directed toward Penfield’s reference to the brain as a tape recorder, though he didn’t say so specifically. Instead, Lashley simply dismissed “the analogies of various machines and neural activity” and pointed to “a curious parallel in the histories of neurological theories and of paranoid delusional systems. In Mesmer’s day the paranoiac was persecuted by malicious animal magnetism; his successors, by galvanic shocks, by the telegraph, by radio, and by radar, keeping their delusional systems up-to-date with the latest fashions in physics. Descartes was impressed by the hydraulic figures in the royal gardens and developed a hydraulic theory of the action of the brain. We have since had telephone theories, electrical field theories and, now, theories based on the computing machines and automatic rudders. I suggest that we are more likely to find out how the brain works by studying the brain itself and the phenomena of behavior than by indulging in far-fetched physical analogies.”
As for the “memory mechanisms” that Penfield propo
sed, Lashley was unconvinced. “Dr. Penfield’s observations on stimulating the temporal lobe raise many problems,” Lashley said, “but I do not believe that they justify the conclusion that memories are stored specifically in that region.” He admitted that he had “no clear alternative to offer in explanation of Dr. Penfield’s data” but added that whatever that data proved or didn’t prove, it would be hubristic to give it too much credence. The functions of the temporal region were still, he said, “completely obscure,” noting that when he, Lashley, had destroyed the visual processing areas in animals, it did “not abolish visual memories” and that when he likewise destroyed the tactile areas, it did “not abolish tactile memories.” Finally, Lashley wasn’t even convinced that the so-called memories Penfield described provoking were memories at all. Despite the fact that “Dr. Penfield considers that he is stimulating specific memory pathways,” Lashley said, we still had no idea “what cerebral processes arouse memories.”
The transcript of the meeting does not record whether Penfield at this point removed his glasses. He did, however, respond.
“Dr. Lashley,” he said, “pointed out, as I feared that he would, that in his opinion there are no specific memory traces. That is in keeping with his observations in the early days in Minneapolis, when he worked with rats. It is in keeping with his demonstration of the replaceability of areas of brain, functional areas of brain, one by the other. Yet if there are no recording patterns in the cortex, how is it that an electrical stimulus can cause the patient to reexperience an earlier experience?”
Then he added a jab of his own.
“I would point out,” he said, “that the replaceability seems to be somewhat less as one rises in the evolutionary scale.”
In other words, Lashley might be an expert on the minds of rats, but Penfield’s expertise came about through his work with an entirely different category of animal.
—
At the end of the day, and the end of the conference, Penfield had presented some intriguing case studies, but he lacked the necessary evidence to support a real theory of how memory worked. Even if it was assumed that the brain contained a sort of tape recorder—or, for that matter, a telegraph, computer, or hydraulic pump—that allowed us to preserve our experiences, Penfield’s operations hadn’t given any idea as to its location. Just because stimulating a certain part of the brain cued up a particular recording didn’t say much about where that recording originated or how it was made. To use another metaphor Lashley would disapprove of, when you tune a radio to a particular station and hear a particular song coming out of it, it doesn’t tell you where the radio station is located physically, or the studio where the song was originally recorded.
Was there a seat of memory in the brain?
Karl Lashley would say no, but Wilder Penfield felt otherwise. The brains of rats might exhibit equipotentiality, each part equally important and capable when it came to memory, but Penfield’s experiences had led him to a less democratic view. He was already famous for mapping out in great detail how various parts of the brain were dedicated to different actions and sensations. Why should the brain exhibit any less specialization when it came to something as fundamental as memory?
Penfield was a devout Christian. He had faith in the existence of a higher being, though of course he had no proof.
He also believed in the seat of memory.
He had no proof of that, either.
—
When Anwyn and I got back home from Sifnos, I did some research on Mnemosyne, the goddess of memory. I wanted to see if her story was any more fleshed out in books geared toward adults than it was in the version presented for kids in D’Aulaires’ Book of Greek Myths. The answer, it turned out, was no, not really. Despite her obvious importance—Mnemosyne is credited with not just the creation of memory but the creation of language itself—her biography is always paper-thin, a collection of isolated fragments. She had long hair, she slept with Zeus, she gave birth to the Muses, she wore a golden robe. That’s about all there is.
This doesn’t mean people didn’t write about her and reify her. They did.
Here was Homer, describing how Hermes viewed her:
“First among the gods he honored Mnemosyne, mother of the Muses.”
Here was Hesiod, describing her love life:
“For nine nights did wise Zeus lie with her, entering her holy bed remote from the immortals. And when a year was passed and the seasons came round as the months waned, and many days were accomplished, she bore nine daughters, all of one mind, whose hearts are set upon song and their spirit free from care, a little way from the topmost peak of snowy Olympus.”
Here was Pindar paying tribute in one of his odes, making the point that no glory endures if nobody remembers it:
“Even high strength, lacking song, goes down into the great darkness. There are means to but one glass that mirrors deeds of splendor; by the shining waters of Mnemosyne is found recompense for strain in poetry that rings far.”
But Mnemosyne’s own story, her trials and tribulations, whatever they were, has been forgotten. The Greek pantheon of gods and goddesses is so vast that some characters are bound to be more fleshed out than others, but it struck me as unjust somehow that the story of the mother of all stories would get such short shrift.
Plato, in one of his Socratic dialogues, chronicled an interesting conversation that the Greek mathematician Theaetetus had with Socrates in 369 B.C.E. As far as I can tell, this conversation contains the earliest known attempt at a scientific explanation for how memory works. It straddles both worlds, though: Socrates’s concept of memory doesn’t entirely let go of Mnemosyne. Instead he steps tentatively into the realm of secular reason while keeping one foot in the old mythos. He also uses yet another metaphor for the inner workings of the mind that no doubt would have gotten under the skin of Karl Lashley.
Socrates: Please assume, then, for the sake of argument, that there is in our souls a block of wax, in one case larger, in another smaller, in one case the wax is purer, in another more impure and harder, in some cases softer, and in some of proper quality.
Theaetetus: I assume all that.
Socrates: Let us, then, say that this is the gift of Mnemosyne, the mother of the Muses, and that whenever we wish to remember anything we see or hear or think of in our own minds, we hold this wax under the perceptions and thoughts and imprint them upon it, just as we make impressions from seal rings; and whatever is imprinted we remember and know as long as its image lasts, but whatever is rubbed out or cannot be imprinted we forget and do not know.
The world evolved in countless ways during the 2,320 years between the end of that conversation and the end of Wilder Penfield’s presentation to the American Neurological Association.
Our understanding of memory, however, had advanced very little.
EIGHTEEN
FORTUNATE MISFORTUNES
My mother remembers that during the years immediately following the war, my grandmother would continue to go away sometimes, for days or weeks or months. The children never understood these absences. One day their mother would be home, the next she’d be gone, and a nanny would move into the house until my grandmother returned. My mother remembers that by 1950 the absences were fewer, and my grandmother seemed more stable, less agitated, less upset. She even became a girl-scout troop leader. She would host my mother—just entering her teens—and the other scouts, teaching them sewing and jewelry making, two skills that she might have honed during her time at the Institute of Living, in the little arts and crafts colony near Pomander Walk.
My grandfather pushed my mother’s brothers, hard. He had their IQs tested, and then told them whose was higher. He yelled, he bullied. My mother remembers thinking that the reason he didn’t put equivalent pressure on her—she was never a good student, and he never seemed to care—was that she was a girl, and he didn’t believe that a girl’s grades mattered much. She remembers being grateful for this. Her older brother, Barrett, respon
ded well to the pressure. He excelled. Her younger brother, Peter, did not. Peter had a difficult time, growing up. He moved from school to school. He acted out.
My mother remembers that the best days, for the family as a whole, were the ski trips. When my grandmother was not away on one of her unexplained absences, and my grandfather was not at work; when nobody was fighting; when, early on a Sunday morning, they would squeeze into their ski clothes and their ski boots, then squeeze into a car and head off to a mountain: to Stowe, Bromley, Otis, Mohawk, or Mad River Glen. Often, on the way to the slopes, my grandfather would suddenly pull into the lot of some small church in some small town. My grandmother was not religious, and held her nonbelief as a point of pride until the day she died, but she would march into the church along with the rest of them. My mother remembers wondering what the men and women in the pews thought of her strange, complicated family as they entered those sacred spaces and clomped up the aisles in their ski boots.
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