What is a memory? What launched the study of memory? How can our knowledge of memory serve us in the future?

Scientific American opinion editor Mike Lemonick and Princeton professor of neuroscience Dr. Sabine Kastner addressed these questions in conversation with Stevie Bergman and Brian Kraus, co-hosts of These Vibes Are Too Cosmic, a science journalism radio show on WPRB. They were joined by the Princeton Laptop Orchestra (PLOrk, for short) in Taplin Auditorium on Friday, February 24th. Around two hundred attendees filled the seats.   

PLOrk opened the event, playing the These Vibes theme song—an ambient, electronic swing that immediately set a curious theme. Dr. Kastner kicked off the discussion by establishing the important difference between episodic (declarative) memories—experiences, knowledge of people one has met—and procedural (non-declarative) memories, which are passive skills. Dr. Kastner noted the importance of the hippocampus in the retention of declarative memories.

“If you were to remove that part of the brain… you wouldn’t be able to remember you were here tonight,” she said.

Stevie then asked about a curious case in neuroscience: the patient known as H.M. He was a 27-year-old man who suffered from crippling epileptic seizures. He was physically unable to focus in school and could not work a demanding job. Doctors believed that the hippocampus was the source of the problems—at the time, its function was largely unknown and the subject of much debate. So, in an experimental treatment, the doctors removed both sides of H.M.’s hippocampus. Lemonick described the procedure as “sucking out his brains.” The audience collectively winced.

While the procedure did ease the man’s seizures, it came with an unforeseen side effect. Every so often, when a doctor re-entered his room, it was as if H.M. were meeting them for the very first time. He repeatedly did not remember meeting anyone, nor could he remember his life prior to the surgery. He had lost his ability to form episodic memories; however, he retained his procedural memories, and was able to practice and develop his hand-eye coordination and motor skills. 

H.M.’s peculiar case of amnesia launched a thriving investigation on memory. The hippocampus was regarded with newfound importance, and research on the surrounding area of nerve cells was performed on animals. Since rats don’t form autobiographical memory, the research was somewhat limited. Still, it helped researchers build models of what may happen.

Lemonick chimed in: “I met those rats, by the way!”

We then went from listening about the brain to listening to it, via a PLOrk piece titled Connectome. It was composed by Mike Mulshine and described by fellow PLOrk member Jeff Snyder as “computing an equation in real time.” Assisted by Dr. Aatish Bhatia, associate director at the Council on Science and Technology, the group created a model of a neuron, then composed a piece based on what it would sound like.

“It sounds kind of strange…but we think it’s pretty fun,” said Jeff Snyder, who composed the These Vibes theme song. He went on to describe the piece as “connecting us like neurons connect to dendrites.” A large image was projected over the orchestra —Princeton student Drew Wallace ‘17 created a visual that was generated in real time by live data.

At the same time symphonic and cacophonous, this neuron model audio synthesis combined computerized bleeps and screeches with a clopping of woodblocks. The images projected overhead were thin, black lines that conglomerated into large blobs. The blobs had black tendrils that reached out farther and farther as the piece continued, connecting with other similar entities. At the end of the piece, the tempo of the woodblocks continued to shift until each member was tapping their block in perfect unison.

“When all your neurons fire in unison like that, it means you’re having a seizure,” Dr. Kastner informed us, much to our surprise.

We then learned about a second peculiar case of memory loss: Lonni Sue Johnson. A multi-talented Princeton native, she was a musician, a private pilot, and an illustrator best known for designing covers for The New Yorker.

In 2007, Johnson suffered from a brain disease called encephalitis. It consumed her entire hippocampus, and, like H.M., she lost her episodic memory.

Johnson continued to live in “time windows” of indeterminate length. Her procedural memory, however, was still strong.  Lemonick recalled an experiment in which researchers composed an extremely technically difficult piece of music for her to play. She was presented the same piece repeatedly—each time, the researcher would tell her it was a new piece, and each time she believed it was her first time seeing it. After weeks of playing it, each time a “new” experience for her, the researchers found that she was becoming more adept, further highlighting the separation between memory of experience and retention of physical skills.

But there were a few peculiarities about her case. For example, she could still remember that she was a private pilot prior to the surgery. Lemonick and Dr. Kastner asserted that Johnson could remember general information, but not specifics.

Working with Johnson was an exercise not just in understanding the brain, but in understanding the research’s purpose.

“Lonni Sue always asks, ‘Will this help people?’” Stevie mentioned. What would the effects of the research have on future patients?

The answer was: an accumulation of knowledge. Dr. Kastner stressed the importance of “basic research”—trying to understand what the fundamental functions are, and how they can be manipulated. The information gathered helps science progress—toward what, however, remains unknown. 

Lemonick summed it up well: “Research is how we make progress.”

On that note, the Princeton Laptop Orchestra performed a closing piece, “PLOrkCycler,” based on how we remember pop music. The performers behind the laptops played sound collages made from pop music selections. The drummer, guitarist, and bassist then improvised over these recordings.

Improvisation based on memory was a fitting end to the night. Progress is built upon what we know, through personal experience and in research. It’s like paving a road, except we don’t know where it leads. Which is why we all have to improvise.

These Vibes Are Too Cosmic airs on WPRB every Tuesday night, from 6-8 p.m. EST.