How Stroke Breaks the Word-Brain Connection

It’s well known that stroke victims may struggle with reading, but the real question has always been—why? Recent research has finally provided the answer (1^✔ ✔Trusted Source
Study identifies why stroke impairs ability to use word meanings in reading

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When Stroke Steals the Meaning from Words

A recent study conducted by Georgetown University researchers found that stroke can impair a person's capacity to use word meanings to aid in word recognition when reading.

The study looked at scanned images of brains damaged by stroke while they were made to read aloud. By doing so, they were able to find out the part of the brain that was responsible for deciphering the meaning of words, which facilitated their reading. That is how they found out that the stroke survivors struggled to use word meanings within sentence context; they couldn’t connect the words they were trying to pronounce back to the ideas behind the words.

Language Processing Center: The Brain Target Spot

The study included two groups of patients

1. 56 participants who were stroke survivors (left hemisphere)
2. 68 participants with no history of stroke

The researchers focused on the left side of the brain in stroke patients because that is where the language processing center is located. Compared to phonological impairment, or the capacity to sound out words, which is present in the majority of stroke patients, processing the meaning of words was far less common and milder.

Do Highly Imageable Words Make a Difference?

The relationship between imageability and success while reading aloud words, using imageability as an indicator of a word's depth of meaning.

• Words with a high imageability, like "hammer" or "cow," are easy to visualize.
• Words with low imageability, like “justice,” are harder to visualize. Even imagining Lady Justice holding balance scales only symbolizes the concept, rather than providing a direct visual, something that can confuse the brain.

For a better understanding, the researchers used MRI imaging to map the extent of the strokes with the word "imageability." The images showed that damage to the superior temporal sulcus—a brain region involved in speech processing and auditory short-term memory—reduced the ability to read high-imageability words compared to low-imageability ones.

This indicated a failure to use meaning to support reading. Researchers also identified an overlapping brain area linked to deficits in phonology—the ability to connect a word’s meaning to its sounds. Together, these findings suggest that poor integration of meaning and phonology contributes to specific reading difficulties in stroke survivors with left hemisphere injuries.

To better understand the effects of strokes, a recent 5-year funding from the NIH will compare reading in normal aging to those who have experienced a left-hemisphere stroke.

Reference:

1. Study identifies why stroke impairs ability to use word meanings in reading - (https://www.news-medical.net/news/20250813/Study-identifies-why-stroke-impairs-ability-to-use-word-meanings-in-reading.aspx)

Source-Eurekalert