How the Brain Retrieves Sound Knowledge: A TMS-Powered Peek Inside

At Goodwin Health Café, we’re constantly exploring the fascinating crossroad where mental health, neuroscience, and innovation meet. Today, we’re highlighting a breakthrough study that explores a very specific—and surprisingly complex—piece of how our brains work: how we retrieve sound-related knowledge. In other words, how do we “know” what a bell sounds like, or a siren, or a violin—even when we’re just reading those words?

To answer that, researchers turned to a tool we’re quite fond of here: Transcranial Magnetic Stimulation (TMS). But this wasn’t your everyday TMS session—this study pushed boundaries with a clever design and precision targeting that opens new doors in understanding human cognition.

A Quick Dive Into Conceptual Knowledge

Our brains store an incredible variety of information, from the sound of ocean waves to how to tie a shoe. These stored bits of meaning—what neuroscientists call "conceptual knowledge"—are what help us make sense of the world. But it turns out, retrieving these different types of knowledge isn’t a one-size-fits-all process.

In fact, the brain may use different routes depending on the kind of information you're trying to retrieve. The left inferior parietal lobe (IPL), a region known to integrate information from various senses, works in concert with other brain regions to retrieve concepts like sounds and actions.

This study set out to answer a vital question: Is the partnership between the IPL and the auditory cortex essential to sound-related conceptual knowledge—or just helpful?

How the TMS Study Worked (And Why It’s Groundbreaking)

To test this, researchers recruited 24 healthy participants and used a combination of offline and online TMS—noninvasive brain stimulation techniques that can temporarily disrupt brain activity in targeted regions.

First, they applied offline TMS to one of three regions:

• Auditory cortex (the sound-processing center)

• Somatomotor cortex (related to physical actions)

• Sham stimulation (essentially a placebo)

Then, while participants performed a task involving written word judgments, online TMS was delivered to either the left IPL or to a sham site.

The task was simple in design but powerful in implication: Participants had to judge how much a word was associated with either a sound or an action—think words like "bell" (high sound, low action) or "run" (low sound, high action). What made this design especially clever was the focus on low sound-low action words—neutral territory that would rely more heavily on brain processing rather than automatic associations.

Even more impressive? The study used personalized electric field modeling to fine-tune the TMS delivery, making this one of the most precisely targeted studies of its kind.

Citation:

Kuhnke P, Numssen O, Voeller J, Cheung VKM, Weise K, Kiefer M, Hartwigsen G. Left inferior parietal lobe and auditory cortex jointly contribute to sound knowledge retrieval. Brain Stimulation. 2025 May 16;18(4):1037–1047. doi: 10.1016/j.brs.2025.05.113. PubMed PMID: 40383298