Does Music Unlock Memory?

USC faculty are getting closer to understanding what happens in your brain when you hear a familiar song - which could affect those struggling with dementia and Alzheimer's disease.

Go put on one of your all-time favorite songs, one that you've been listening to your whole life. What thoughts go through your head? Memories of home? The first time you saw the love of your life?

Nostalgic music - music that we tie strongly to a point in our lives - can evoke deep emotions across the age span. The root of this phenomenon has remained a mystery, but studies have shown that music can generate strong emotional responses - both to calm and invigorate.

A team of USC scientists is getting closer to understanding what happens in your brain when you hear a favorite song - and the results might have profound effects on those struggling with dementia and Alzheimer's disease.

"Listening to nostalgic music not only elicits the traditional memory networks of the brain, but it also involves the reward, narrative and self-processing systems of the brain," says USC researcher Assal Habibi, who directs the USC Dornsife Center for Music, Brain and Society. "These are the mechanisms in the brain by which we think you can listen to 10 seconds of nostalgic music, and it can take you back to something vivid, like your high school prom. We could then use that music as a way of really helping individuals with Alzheimer's disease and other dementias."

Music, movement and learning

Understanding how music affects cognition and the brain as an organ are the twin interests underlying Habibi's work. An associate research professor of psychology at the USC Dornsife College of Letters, Arts and Sciences, Habibi uses various tools, including neuroimaging and psychometric testing, to measure what environmental factors such as music do to our brains.

As founder of the center, Habibi sought to bring together experts from USC Dornsife, the Keck School of Medicine of USC, the USC Thornton School of Music and the USC Viterbi School of Engineering to study music and the impact it has on our emotions, movement and learning. Founded in 2023, the center is currently pursuing three lines of research.

One project explores how learning how to play a musical instrument helps foster better cognitive and language skills in the developing child's brain. The research, done in partnership with the Los Angeles Philharmonic's youth orchestra program and Heart of Los Angeles and funded by the L.A. Philharmonic and GROW at Annenberg Foundation, has also led to new insights into the connection between music and emotional regulation.

But it's the project on triggering emotions that gets at the heart of why music resonates with us so strongly.

"Our hope is that by understanding how music evokes nostalgia and autobiographical memory in healthy younger and older adults, we'll be able to apply these findings to older adults with neurodegenerative diseases like Alzheimer's disease and other related dementias," Habibi says.

Unveiling lost memories

To investigate how nostalgic music could assist people in recalling memories, Habibi and doctoral candidate Sarah Hennessy tapped experts in machine learning, MRI and psychology to pinpoint what happens in the brain when music unveils a lost memory. To grade how well a participant could recall a memory, the researchers assigned a value to its "vividness," Habibi says. She describes it as a formula psychologists use to measure how "detailed your perception and sensation of experience are in your description."

"Vividness measures the amount of detail that goes into your description of a memory," Habibi says. "If I just ramble on like, 'I went to the grocery, then did this and that,' that's not really remembering your memory, but just the state of it. But if you have details like remembering that the room was dark, that is a more vivid memory."

The idea has borne two parallel studies from Habibi and Hennessy.

The first had two groups of people, 30 younger and 30 older, who gave the researchers a playlist of songs that evoked powerful memories and emotions. The researchers then used an algorithm developed by Hennessy and colleagues at Viterbi School of engineering to find songs very similar to the ones on the self-selected playlist to serve as a control.

The participants then entered an MRI scanner to scan their brains as they listened to the nostalgic songs, the control songs, and then completely unfamiliar music. Afterward, the participants were asked to describe memories tied to the nostalgic music and the researchers assigned a vividness score. Hennessy says the neuroimaging results were "amazing."

"When you hear nostalgic music, there's activity all over your brain, but most notably in the default mode network, which is normally active when we're daydreaming," she says. "It is also active when we're thinking about our own narrative. We also have activity in some visual areas that normally process what you see in front of you. But all these participants had their eyes closed. So, what might be happening is that participants are is visualizing what was in front of them during the memory the song evoked."

Enhancing quality of life

In the second study, a separate group of 150 people of color - were played different types of music over 12 weeks. Some weeks, they heard nostalgic music. Other weeks, they listened to familiar music that was not nostalgic. The participants were then asked to describe an autobiographical memory tied to the song or music. Again, the researchers assigned a vividness score to the participants' responses.

The study's results, which will form the basis of an upcoming paper, will help reveal whether nostalgic music evokes a more vivid memory. Habibi says understanding why music provokes a response in reward and narrative systems of the brain could be used "as a way of therapeutic interventions for individuals with dementia."

"This specific pattern of encoding and retrieval of nostalgic music seems to be unique, and the ability of the music to retrieve autobiographical memories is personalized and relative to your story and narrative," Habibi says. "If nostalgic music can help dementia patients access some memories that are typically not accessible to them, it can enhance the quality of life, even if it's temporary.

"If a patient is with their children, and they can remember a birthday party associated with a song and details of it, it can bring back the richness and emotional connection of that memory," she adds.

Connecting to a sense of self

Habibi and Hennessy continue to investigate the mind-music connection. Habibi, with researchers from USC Thornton and the Alzheimer Disease Research Center, recently received a National Endowment for the Arts Research Lab grant to investigate the "effects of music engagement on hearing, communication, and psychosocial well-being in individuals with, or at risk for, Alzheimer's disease, as well as their caregivers."

Hennessy is scheduled to earn her doctoral degree this May, and presented findings from the MRI study at the NeuroMusic Conference held at McMaster University in Canada in November 2023. The analysis for the study investigating dementia in people of color continues and will be submitted for peer-reviewed publication in the coming months.

Currently, Habibi, Hennessy and doctoral candidate Ellen Herschel are conducting a clinical trial for a music intervention app for individuals experiencing dementia. Habibi says that for many dementia patients, the struggle of not remembering causes a lot of agitation. The app will play music for them that's not necessarily nostalgic but will help support their emotional regulation when they struggle with not recalling a memory.

Hennessy says the researchers hope that understanding how music evokes nostalgia and autobiographical memory in healthy young and older adults will allow future research to investigate how these findings could be applied to older adults with neurodegenerative diseases. "Investigating the mechanism of how music evokes these powerful emotions and memories in the brain can help us understand how music-evoked memories remain relatively spared in Alzheimer's disease and related dementias," Hennessy says.

"Nostalgic music allows us to connect to our sense of self," she adds. "Because this sense of self is often diminished with neurodegenerative disease, the hope is that this type of tailored music intervention might be able to help patients - even if just for the duration of the song - experience a temporary 'return to self' by engaging in these self-referential and autobiographical areas in the brain activated by music."