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What Bats, Bombs and Sharks Taught Us about Hearing [Video]


The most surprising part of this story was that they managed to record brainwave activity from the sharks.

This tale is about one of the most fascinating figures in the history of neuroscience: Dr. Robert Galambos. This is his story.

Right: Robert Galambos, MD, PhD  Source: The New York Times

Decades ago, Dr. Galambos discovered that bats navigate via echolocation (PMID: 12763570). He also discovered (while under contract by the US military to develop a physiological test for hearing loss that couldn’t be faked) that EEG could be used to test the health of the auditory system. If you play a series of sounds while recording EEG, you can pick up the electrical activity from the neurons processing those sounds. This is called the "brainstem auditory evoked potentials".

This test is performed thousands of times each day.

In fact, if you were born in the last 30 years, chances are doctors recorded your EEG when you were a baby, specifically to test your hearing using this method. (PMID: 4809084)

Before I dive into the details of the life and science of Galambos, I'd like to set the scene: it's almost 30 years after the shark experiment(I’ll get to that later), and I'm sitting in a Persian restaurant in Berkeley, California with the man crazy enough to sign off on my PhD. His name is Prof. Robert T. Knight; he’s the director of the Helen Wills Neuroscience Institute at the University of California, Berkeley.

Prof. Knight is sharing stories about Galambos who was his grand-mentor and, therefore my great-grand-mentor.

Both Knight and Galambos go by "Bob".

Although I'm listening to Knight’s tale, every now and again my attention is captured by different events, both internal and external. While such minor lapses and distractions are common in all conversations, as a neuroscientist I also find myself at times being "meta-distracted".

Being a neuroscientist isn’t just a career, it can be a whole different worldview.

I think about why I got distracted; about what my brain is doing. I think about how it is that we are even aware of whether or not we're paying attention to something at all.

When the rich aroma of my lunch grabs my attention, I don’t just think about how hungry I am, I think about how the G protein-coupled receptors that mediate olfaction use labelled lines to map smells. When I get flashes of memory from meeting Galambos several years ago, I don’t just remember his warmth, I think about how emotionally salient events enhance memory encoding.

Apparently meeting him was important to me.

Back in the external world, Knight is telling me about his early career. It's the early beginning of the 1980s and I'm being born a state away. Knight was on an NIH review committee to assess whether a grant application submitted by Ted Bullock was worth funding. At the time, the NIH had their grant review committees perform "site visits" wherein a group of peer scientists would visit the lab of the person requesting funding.

Knight and the rest of committee arrived at Bullock's lab in La Jolla, California, where Bullock and Galambos both worked at UCSD and the Scripps Institute of Oceanography. The grant for which Bullock had applied was for a project to study the phylogenetic origins of the previously mentioned brainstem auditory evoked potentials (BAEP). Galambos was involved with this project because he was the world’s BAEP expert.

The plan was to record EEG from a variety of species including sharks, frogs, dolphins, and monkeys, to figure out how the BAEP differs across species.

The committee members were all seated in an room listening to Bullock discuss his proposal when, according to Knight, Galambos stopped Bullock to say, "Ted! I just realized we have diametrically opposing views of how the brain works!"

Mind you, these men had been friends, colleagues, and collaborators for decades. Bullock then turned to Galambos and said, "Bob, if you'd been paying attention to anything I've said to you in the last 35 years, you'd have realized that by now."

Bullock then continued with his presentation.

After touring their research facilities which included pools for the dolphins, monkey cages, frog terrariums, and a shark tank (!), the committee all piled into their rented station wagon to return to their hotel.

On the short drive back they voted unanimously to recommend that the project be funded. Years later the research resulted in several important publications. (PMID: 6183096)

Knight is full of stories about his friend and former mentor. Galambos was a man whose ideas were at times so controversial that, according to his echolocation collaborator Donald Griffin, when Galambos first presented their findings, "one distinguished physiologist was so shocked that he seized Bob by the shoulders and shook him while expostulating, 'You can't really mean that!'"

Galambos was also an extremely committed scientist. When I met him in 2005 it was after he presented a talk about his new research, "A new look at the visual system."

He was 91 years old at the time.

Left: Robert Galambos, MD, PhD - Source: Scholarpedia

As Knight and I finish our meal, he points me to an autobiography Galambos wrote, telling me about Galambos’s early career, the details of which I’ve filled in from Galambos's autobiography published in The History of Neuroscience in Autobiography by the Society for Neuroscience.

Galambos's autobiography gives some incredible insights into the way his mind worked. He says of himself that he is "often arrogant and cranky" which "turns people off". He also notes that he had some esoteric interests; he once attended a two-day workshop on extrasensory perception (ESP).

He was also remarkably comfortable with self-experimentation.

In his autobiography he shares anecdotes from his early career about how he was lead to study the physiology of hearing. In 1936 he was introduced to the technology behind "single-unit recording", the ability to record the electrical action potentials by which neurons communicate. At the time Galambos worked with future Nobel Prize winner Roger Sperry (who shared the award with David Hubel and Torsten Wiesel). Together, Galambos and Sperry built their own recording system:

Sperry and I fabricated concentric needle electrodes and invented new ones, the most successful of which was a strand of fine copper wire with a single line cut across its insulation with a scalpel blade. We threaded this wire into the eye of a surgical needle, passed the needle through our skin into a muscle and back out, and connected it to the Snodgrass amplifier and loudspeaker. When our muscle contractions caused the loudspeaker to emit loud pops, similar to Lindsley's, we knew the bared surface rested upon one or a few muscle fibers.

Galambos initially used this method to study the physiology behind earthworm locomotion, but he soon began using these electrodes to record neuronal activity from brains of living animals to study hearing.

Between 1939 and 1940, in collaboration with Donald Griffin, Galambos, conducted a series of famous experiments that proved that bats use echolocation to navigate. This was shown using a variety of simple, but elegant behavioral experiments on thebats.

I've uploaded a video to YouTube of the original foootage of the experiments recorded by Griffin, Galambos and collaborators and provided to us by Galambos. All of the details are outlined there:

In short, Galambos and Griffin started by showing that blindfolded bats fly perfectly well. This was demonstrated by stringing wires in a room, from floor to ceiling. Bats easily avoid these obstacles; they do so just as easily when blindfolded. This suggests that bats do not require vision to navigate.

After the blindfold test, they then plugged the ears of the bats and observed that the bats hit several of the wires. Similarly, when the bats were gagged they also flew awkwardly.

Although these experiments showed that vocalization and hearing were required for bat navigation, they didn’t prove that the bats used sound to do so.

Earlier Griffin, along with Harvard physics professor G.W. Pierce, published a paper proving that bats emitted inaudible (to humans) high-frequency cries. This was no small feat, as doing this depended upon a new technology that Pierce had invented: a machine that could generate and record high-frequency sounds.

Using this device, Galambos and Griffin proved conclusively that bats used echolocation. When they played high-frequency sounds in the room, the bats lost all ability to navigate, even when the bats were otherwise unhindered by blindfolds, gags, or earplugs.

Bat echolocation - Source: ASU School of Life Sciences: Ask a Biologist

What impressed me the most about Galambos, though, wasn't his superb research, but rather the extent to which he'd sacrifice himself for his pursuit of knowledge.

I'm fascinated by the history of self-experimentation in neuroscience and medicine and have written about the topic previously. Sir Henry Head severed nerves in his own arm to document how sensation is regained after nerve damage. The history of endocrinology can be traced back to Dr.Brown-Séquard injecting himself with dog sperms to study its effect on his vitality and vigor.

Before reading his autobiography, I had no idea about Galambos’s  self-experimentation.

I've already mentioned how he and Sperry were threading electrodes under their skin, but that's just the beginning. According to Galambos, he once volunteered to stay awake for 53 hours for a sleep deprivation study run by Seymour Fisher.

In another experiment conducted in response to the bombing of Pearl Harbor in 1942, Galambos and hearing researcher Hallowell "Hal" Davis were asked to "find out how much and what kind of sound it takes to injure or incapacitate a man."

How did they test this? Galambos explains:

we proceeded to expose our ears to the sound waves emitted by a so-called bullhorn, the kind of loudspeaker the Navy used to deliver messages to personnel wearing earplugs on the busy flight deck of an aircraft carrier. We systematically varied the three sound variables--intensity, frequency, and duration--producing in ourselves increasingly larger temporary hearing losses, until we neared combinations we thought might cause a permanent loss. At the end of the project, Hal decided to find out if our predictions were correct, and told us to expose his right ear--we always protected his left ear--to a wideband noise at 130 dB for 32 minutes. As predicted, this exposure permanently sliced a few hundred Hz off the high end of his existing congenital hearing loss in the 3500-3800 Hz region.

They partially deafened themselves! For science!

But that's not all:

In the summer of 1942, Hal sent the two of us to Woods Hole to find out whether underwater explosions are hazardous for the ears. Some physicists were exploding bombs in the harbor there, and we were supposed to jump in and have our heads submerged when this happened. We spent several beautiful summer days taking turns jumping off the pier at the Oceanographic Institute. The plan required comparing before and after audiograms, and we began with blasting caps detonated at 50 feet or so. When we detected no losses following detonations so close that we were afraid we might be wounded by shrapnel, we began jumping in when the blasters signalled a bomb of theirs was about to go off. They supplied us with pressure data from their sensors, and I recall really impressive shock waves compressing my body, but neither of us ever recorded a hearing loss.

Galambos turned out to be one of the most dynamic figures I've encountered in the history of neuroscience. I’m proud to count myself as a part of his scientific lineage and can only hope my research is so daring.

He was a scientist who was willing to take chances in his pursuit of truth.

One of his hypotheses--that glia are important contributors to brain function was met with such harsh criticism that he was forced to change jobs because of it. At the genesis of his hypothesis, Galambos exclaimed "I know how the brain works", a phrase which I'm certain many a neuroscientist has uttered at some point in their careers.

My wife and colleagues can certainly attest to my own proclivity for proclaiming "I've figured out the brain!"

But despite his (perhaps reckless) scientific adventurousness, his advice is clear:

To the graduate student who asked how many mistakes one is allowed to make during his career, I answer none at all, and then add that if you must make one have it be really big, and save it until you hold a tenured faculty position.

So I guess my question is this: would you rather be "arrogant and cranky" like Galambos, or play it safe until tenure? I don’t think Galambos took his own advice.

As for me?

I'm headed down to the pier to run some experiments. Sharks and bombs be damned.

About the Author: Bradley Voytek (@bradleyvoytek) is a post-doctoral researcher at UCSF. He’s got some strange interests. He earned his PhD in neuroscience from Berkeley in 2010 where he researched how brain regions communicate to give rise to cognition in normal health and after brain injury. His research and blogging has appeared in The Washington Post, Wired, and The New York Times. With his wife, Jessica, he runs His non-academic… uh…. interests, include examining the zombie brain as part of his science outreach. He's also a consultant for The National Academy of Sciences - Science & Entertainment Exchange. He blogs at In 2006 he split the Time Person of the Year award.

The views expressed are those of the author and are not necessarily those of Scientific American.


The views expressed are those of the author and are not necessarily those of Scientific American.

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