November 15, 2011 | 1
WASHINGTON, D.C.— Wandering through what seems like miles of presentations, posters, and excited scientists at the Society for Neuroscience (SfN) meeting, I can’t help but overhear a lot. Conversations about everything from the ventral medial prefrontal cortex to fMRI; social rewards to serotonin. There is something about the buzzing hum of thousands of voices and echoes that sounds almost musical.
A few of these conversations are more musical than the rest, including the following tidbits presented here this week on the latest research on music and the brain.
For the first study, think Memento meets Beethoven. A 68-year-old cellist, “PM,” has lost all of his memories and has trouble making new ones. He can’t name any famous landmarks or events, recall important moments from his past, or even remember what day of the week it is. But he is still able to remember musical compositions. He recognizes famous compositions from before 2005 (the year he lost his memory), and can distinguish them from post-2005 musical pieces. He is also able to remember his emotional responses to music he heard a few hours ago (although he won’t remember much else from a few hours ago). Researcher Carsten Finke of the Charité – Universitätsmedizin Berlin thinks that this case demonstrates a striking fact: there is something about musical memory that sets it apart from other types of remembering.
But while PM’s case is bizarre, it’s also just a single case. What else is out there on amnesia and musical memory? Actually, not too much. There haven’t been many chances to study the subject (it’s not everyday you happen to find a professionally trained musician who has also had his memory nearly wiped clean). However, in the 1990s there was a case of a patient who had the opposite problem. This patient had lost his memory for music entirely, but only music. All other cognitive functions remained intact. This patient didn’t have amnesia, but had suffered lesions in a particular part of the brain: the superior temporal gyrus.
As luck would have it, another researcher at SfN (and presenting down the hall from Finke) also studies that region of the brain. Perhaps it is not surprising that he thinks it might more accurately be called the brain’s “pitch center.”
Sam Norman-Haignere and other neuroscientists at MIT stumbled upon their discovery by accident. “We were looking for a music region,” he said. “Instead, we found a pitch region.”
Now, there’s some controversy over whether just one area of the brain is responsible for processing pitch, or if it’s a whole distributed network. Norman-Haignere’s study compared the fMRI scans of people listening to different sounds. First they listened to a bunch of synthetic sounds, comparing resolved versus unresolved chords, or notes that were in harmony or sounded dissonant. Then they switched to natural sounds, such as singing versus regular speech. The MIT researchers found that the superior temporal gyrus had a much stronger response to music than random noise or speech.
Norman-Haignere admits this study is just a start. For one, it only tested a few people (one experiment examined two people, another eight). But he thinks that finding specific neural mechanisms that process pitch is an exciting beginning to a much more detailed investigation of the neuroscience and experience of music perception. He’s interested, for example, in why we are better at recognizing certain aspects of pitch than others. People are pretty good at distinguishing relative pitches—it’s how we recognize a familiar tune even if the particular notes are much higher or lower than the original. But we’re really bad at distinguishing absolute pitches (for example telling the difference between the same song in two different keys). “If you move up a pitch, people hear the same thing,” he said.
Except perhaps, those rare people with perfect pitch. I wonder how they would fare in one of Norman-Haignere’s studies.
Pitch also turns up in places where you wouldn’t expect. Like in studies on bilingual children. Jennifer Krizman of Northwestern University, presenting just a few steps away from the MIT group, studies a group of 14-year-old kids from Chicago. Half of them speak both Spanish and English, and the other half speak only English. Recently, she tested how well these kids could hear a specific sound (the word “dah”) against either a quiet background or in the midst of lots of other babbling.
Interestingly, the bilingual children were much better at picking out the particular sound in the midst of all the noise. As Krizman puts it “they were better able to focus on the relevant areas of the soundscape.”
How come? Well, a few previous studies have shown that when bilinguals switch languages, they will actually switch the pitch of their voice. This seems to suggest that pitch holds meaning on multiple levels for bilingual talkers. After a lifetime of exposure to manipulating sounds across different audiences, suppressing particular sounds of one language over another, and having to categorize different sounds in their environment, bilinguals may have fine-tuned their ability to hear.
Perhaps not surprisingly, there is another group of people who are very good at pulling sounds from noise, and for whom pitch matters a lot: musicians. According to Krizman, trained musicians, like bilinguals, “can filter out what’s irrelevant in their auditory scene.”
Let’s hope some of them show up at the SfN Music Social.
Image courtesy of Flickr/photosteve101