Telegrams and Sentence Monsters
How brain damage reveals the machinery behind the gift of gab.
Posted September 10, 2025 | Reviewed by Monica Vilhauer Ph.D.
Imagine trying to speak but only being able to produce fragments: "one eye – eye is always – tears – been teary – I can't – I could earlier." Or imagine speaking fluently but creating bizarre "sentence monsters" like: "Well, all I know is, somebody is clipping the kreples and some wha, someone here on the kureping arm." These aren't made-up examples—they're actual utterances from people whose brains have been damaged by stroke, revealing something profound about how our minds construct language.
The Mystery of Missing Grammar
In the late 1800s, many scientists viewed language simply as a collection of words stored in different parts of the brain—like a mental dictionary with separate sections for hearing words and speaking them. But some clinicians noticed something peculiar: certain patients could remember words quite well but couldn't string them together properly while speaking.
In the 1870s, German physician Adolf Kussmaul was among the first to systematically study these sentence-level problems. He identified patients who spoke in halting, telegraphic fragments lacking many connecting words, termed “agrammatism,” and others who produced flashes of complex syntax but with a tangled organization, so-called “confused sentence monsters,” today’s “paragrammatism.”
The Great Syntax Hunt
The 1950s brought a revolution in thinking about language. Linguist Noam Chomsky proposed that grammar wasn't just learned sequences of words but an innate, uniquely human capacity involving complex hierarchical structures. This sparked an intense hunt for the brain's "syntax center"—the neural headquarters of our grammatical abilities.
The prime suspect was Broca's area, a region in the left frontal lobe already famous for its supposed role in speech production and, when damaged, was thought to cause agrammatism. When researchers in the 1970s discovered that people who struggled with agrammatism when they tried to speak also had trouble understanding sentences with complex syntax (like, "The mother that the child kissed is happy"), it seemed like the case was closed. Here, finally, was the brain's grammar center, controlling syntax for both speaking and understanding.
But the plot thickened as researchers dug deeper. Specifically, it was found that agrammatism in expression and comprehension did not always co-occur. Moreover, the two abilities were linked to entirely different brain areas: Broca’s area for expressive agrammatism and the posterior temporal lobe for receptive agrammatism. Adding to the puzzle, difficulty with syntax in comprehension was recently found to be associated with paragrammatism, which is also associated with temporal lobe damage.
These discoveries have led to a new understanding of how our brains handle grammar. Rather than having a single "syntax center," we appear to have a distributed network with different components handling different aspects of grammatical processing. The breakthrough came from recognizing that building grammar involves two fundamentally different computational challenges: creating hierarchical relationships between words and arranging them in the right linear order.
Recent research suggests our brains solve grammar using a two-part system. The temporal lobe, particularly an area called the posterior middle temporal gyrus, appears to specialize in building hierarchical relationships—figuring out which words modify which, what the subject and object of a sentence are, and how different parts of a sentence relate to each other.
Meanwhile, subregions of Broca's area and surrounding areas seem to handle a different but equally important job: linearization. When we speak, we need to take our complex, multi-layered thoughts, arrange them into syntactic hierarchies, and then transform the hierarchies into a single-file line of words that unfolds over time. This sequencing process appears to be a specialty of this more frontal brain system in and around Broca's area.
This division of labor explains many puzzling observations. Why do people with temporal lobe damage struggle to understand complex sentences? Because they can't properly build the hierarchical relationships that give sentences their meaning. Why do they also produce sentence monsters while speaking? Because they can’t organize thoughts into syntactic hierarchies. Why do people with frontal lobe damage produce telegraphic speech? Because they have trouble converting their hierarchical structures into properly sequenced words.
Understanding how grammar breaks down doesn't just satisfy scientific curiosity—it has real-world implications. With this knowledge, for example, speech therapists may be able to design better treatments by targeting the specific component of the grammar system that's damaged, and neurosurgeons will have a more accurate road map as they navigate the brain's networks.
This research also reveals something profound about human nature. The fact that grammar can break down in such specific ways suggests that our capacity for language really is special—not just a general learning ability, but a dedicated system with its own neural architecture. Grammar isn't just about following rote-learned patterns. It's about the fundamental human ability to take complex thoughts and transform them into hierarchies, sequence the elements, and then convert them into sounds that can be decoded by a listener, thus recreating your thoughts in their mind.
The next time you effortlessly parse a complex sentence or find just the right turn of phrase to express an idea, remember that you're using a complex neural system with multiple moving parts, one that took over a century to begin to understand. The breakdown of language in brain injury, tragic as it is for those affected, continues to illuminate the extraordinary machinery that makes us uniquely human.
Excerpted and adapted from “Wired from Words: The Neural Architecture of Language” by Gregory Hickok, a forthcoming book published by MIT Press, available for pre-order prior to November 2025 publication.
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Matchin, W., den Ouden, D. B., Basilakos, A., Stark, B. C., Fridriksson, J., & Hickok, G. (2023). Grammatical Parallelism in Aphasia: A Lesion-Symptom Mapping Study. Neurobiol Lang (Camb), 4 (4), 550-574. doi:10.1162/nol_a_00117
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Rogalsky, C., LaCroix, A. N., Chen, K. H., Anderson, S. W., Damasio, H., Love, T., & Hickok, G. (2018). The Neurobiology of Agrammatic Sentence Comprehension: A Lesion Study. J Cogn Neurosci, 30 (2), 234-255. doi:10.1162/jocn_a_01200
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Greg Hickok, Ph.D., is Distinguished Professor at the University of California, Irvine, and the author of the forthcoming book Wired for Words.
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