Key points

• Speaking fluently involves organizing the precise sequence of sounds required to say words.

• A brain region called the middle precentral gyrus appears to play a key role in organizing sequences of sound.

• Disrupting this region causes stuttering, hesitations, or speech errors.

Every day, we speak thousands of words, without rehearsal or hesitation. We order coffee. We soothe a child. We describe a memory, tell a joke, argue, confess, comfort, persuade. To us, speech feels as natural as breathing. Yet from the brain’s perspective, it is anything but simple.

New research published in Nature Human Behaviour suggests that speech fluency rests on an intricate, moment-to-moment system for sequencing sounds in the correct order. This process is so seamless that we rarely notice it, unless something goes wrong. But inside the brain, a specialized region is working tirelessly to prepare each syllable, line them up, and deliver them at just the right time.

This region, the middle precentral gyrus, is a little-known fold of brain tissue tucked in the frontal lobe. It may be the key to why our speech flows like a symphony, instead of crumbling into a clatter of broken notes.

Thought Is Not Enough

To speak is not merely to have a thought. It is to turn that thought into motions: tiny, precise muscular movements of the lips, tongue, vocal cords, jaw, and diaphragm. These parts must dance together, millisecond by millisecond, to produce even a simple word. What comes first? What comes next? How long should each syllable last?

This coordination is what scientists call speech-motor sequencing. This study reveals the middle precentral gyrus, or the mPrCG, to be its architect.

Using recordings from 14 patients undergoing brain monitoring, the researchers asked participants to say short syllable sequences. As people prepared to speak, the researchers saw something surprising: the mPrCG lit up not just during speech, but long before it began. The more complex the sequence, the longer it stayed active, quietly assembling the motor instructions before a single word escaped the lips.

In a sense, the mPrCG was acting like a conductor before the orchestra plays, scanning the musical score and preparing each cue. It was not producing the sound itself. It was preparing the order of operations.

A Glitch in the Machine

But how do we know this region isn’t just reacting to speech, rather than preparing it? To test this, the researchers directly stimulated the mPrCG with gentle electrical currents while participants spoke.

The results were immediate. People who had just spoken fluently a moment before began to pause, stumble, or say syllables in the wrong order. Some dragged out their speech, others inserted unintended gaps.

But when asked to simply repeat “ba-ba-ba,” their speech was perfect. The breakdowns only appeared when the sequence required coordination. It’s like a pianist flawlessly playing a single note but fumbling when asked for a short melody. The hands are fine. The memory is intact. But the choreography is lost.

Interestingly, the mPrCG is located near regions involved in reading and writing. Some patients with damage in this area struggle not only with speaking, but also with forming written sentences or reading aloud. This hints at a deeper principle: the brain may use a shared sequencing system for many types of expression: spoken, written, gestured. Whether you’re typing a text or delivering a toast, the same basic architecture might help you organize your thoughts into a meaningful sequence.

What this research shows is that fluency is not a given. It is constructed, second by second, by systems that work in silence. When those systems fail or falter, the result isn’t just noise; it’s disconnection.

People with speech disorders often describe knowing exactly what they want to say but being unable to unlock the words. This study suggests a clear reason why: The neural blueprint for speech, assembled in the mPrCG, has been disrupted. ​​

Understanding this system could pave the way for better tools to support people with stuttering, aphasia, or other speech coordination challenges. Even for fluent speakers, it offers a reminder: slowing down and practicing articulation may help reinforce the very sequencing networks that make speech possible.

Rewriting the Map of Speech

For over a century, scientists have looked for the “speech center” in the brain. What this study suggests is that there is no single center. Instead, speech arises from a community of brain regions, each with its own role. Some regions select the words. Others control the lips or vocal cords. But the mPrCG appears to do something uniquely human: sequence our intentions into actions.

In daily life, we rarely notice this machinery. But perhaps we should. Because it reminds us of something profound: fluency is not a gift, it is an act of construction. Every sentence we speak is the result of a hidden chain of decisions, prepared and executed with remarkable precision. And when that chain is disrupted, we glimpse the delicate scaffolding beneath our most human act.

What makes our speech powerful is not just vocabulary; it is structure. Without sequencing, there is no fluency. Without fluency, we are left alone with our thoughts, unable to share the stories that make us who we are. Recognizing this hidden complexity can deepen our empathy for those who struggle to speak, and remind us to be patient, whether with others or ourselves, when the words don’t come easily.

References

Liu, J. R., Zhao, L., Hullett, P. W., & Chang, E. F. (2025). Speech sequencing in the human precentral gyrus. Nature Human Behaviour, 1-18.

From The MARVELOUS Language Nerds: https://thelanguagenerds.com/2022/funny-literal-illustrations-of-english-idioms-and-their-meanings/

—and—you’d be surprised how you didn’t notice that before. The words that we use every day are so full of joy and wonder and a lot of fun if taken out of context and played with.

That’s what Roisin Hahessy did. Roisin loves to play with words and put them in humorous illustrations to show their double meanings. For her last project, she went after idioms and everyday expressions to illustrate their literal meanings and the result is a funny batch of witty and funny illustrations that make you both laugh and wonder about the craziness of the English language.

MORE TO COME! WATCH FOR THEM!

CMOS 8.160 in the Spotlight

A key feature of any style is how it capitalizes words in the titles of books, articles, and other works. Most recommend a variation of title case, or what CMOS until very recently referred to as headline style (before the publication of the 18th edition).

And though there are some differences among the major styles—for example, AP and APA capitalize prepositions of four letters or more in a title, whereas for Chicago it’s now five or more—they all specify an initial capital for verbs, regardless of length.

This includes the word “is,” as in the song title “Breaking Up Is Hard to Do” (Neil Sedaka and Howard Greenfield, 1962).* When such a title is mentioned in ordinary text or in a source citation, there are generally no exceptions (see CMOS 13.89). But there are some nuances to consider, including some graphical contexts where it may be appropriate to leave “is” lowercase.

“Is” in Title Case†

“Is” is a mere linking verb, the textual equivalent of an equals sign—and it’s only two letters long. So it’s an easy word to forget to capitalize.

Nor does “is” appear all that frequently in titles, considering its ubiquity in ordinary prose. When it is used, it’s sometimes contracted, which is a good way of minimizing its impact. Take the title of the iconic movie It’s a Wonderful Life (1946). Without the contraction, and particularly with a capital I, the emphasis would shift toward the verb: It Is a Wonderful Life.

“Is” is spelled out in the title of the 1997 movie Life Is Beautiful (a translation from the original Italian), so it gets a capital I in Chicago style.‡ But the word is de-emphasized in the poster art for the theatrical release. Notice how the movie’s title is in caps and small caps except for the word “is,” which is in all small caps—and in a smaller font than any of the other letters in the title:

That works well: “Life” and “Beautiful” are the words that matter most.

Consider also the cover for Sue Grafton’s novel Y Is for Yesterday (G. P. Putnam’s Sons, 2017):**

The connecting words “is” and “for” are both lowercase, which allows the more important elements in the title (namely the Y’s) to stand out. (The preposition “for” would be lowercase in Chicago and most other styles.) In Grafton’s title—as in each of the titles mentioned in this post—“is” plays more of a supporting than a leading role.

A lowercase “is” like the one on the Grafton cover, where the small i alone signals that the word is unimportant, would be unlikely to make it past Chicago’s editorial team. But our publications tend to be scholarly in nature; in fiction and other creative contexts, rules are made to be broken.

What’s the Verdict?

“Is” is a verb, so unless it’s hiding behind a contraction, it should always be capitalized in titles mentioned in the text or in a Chicago-style source citation. But it’s a humble little word that doesn’t always like to stand out. In a graphical setting like a book cover or a movie poster, bigger isn’t necessarily better.

* Note that “Up” is an adverb, not a preposition, in the title phrase “Breaking Up”—and therefore capitalized (see also CMOS 8.160, rule 3).

† The subheads in this post are in title case, but sentence case is also an option for subheads, provided it’s consistently applied across a document (see CMOS 2.22 and 8.159).

‡ Wikipedia’s entry for Life Is Beautiful, as of August 23, 2021 (the day before this post was originally published), mentioned or cited that title twenty-eight times (up to and including the bibliography); in thirteen of those instances—or nearly half—the word “is” was spelled with a small i. Apparently, it’s natural to want to lowercase “is” in a title. (As of July 27, 2025, most of these had been fixed.) Such inconsistency isn’t a problem with the Italian title—La vita è bella—where sentence case (and, by extension, lowercase for è, “is”) is the norm (see CMOS 11.8).

** According to CMOS 7.67, letters used as letters are normally italicized (as when mentioned in text). Ditto for “Yesterday,” a word used as a word—which, according to CMOS 7.66, would normally be set in either italics or quotation marks. In an italic title, however, these distinctions are unnecessary (see CMOS 8.175).

Top image: Life Is Beautiful, by Linnaea Mallette (public domain).