Researchers have discovered that two distinct networks in the brain are activated when a person reads a sentence, working together to integrate individual word meanings and obtain higher-order meaning.
A study, by researchers at UTHealth Houston and published in The Proceedings of the National Academy of Sciences (PNAS), provides valuable insight into the brain's language network and its ability to process complex sentences.
To identify the specific roles and interactions of the brain areas involved in reading, the research team performed recordings from the brains of patients with electrodes surgically placed to localise epilepsy.
Neural activity was measured while patients read three forms of sentences: regular sentences; “Jabberwocky” sentences, which use correct grammar and syntax but contain nonsense words, making them meaningless; and lists of words or nonsense words.
Oscar Woolnough, the study's first author, said: “Our brains are remarkably interconnected and for us to understand language requires a precise sequence of rapid, dynamic processes to occur in multiple sites all across our brain.”
The study's senior author, Nitin Tandon, who is also a professor and chairman of the department in the medical school, emphasised the significance of this research. He explained that using implanted electrodes in the brain offers a unique and unparalleled perspective into how the human mind works, particularly during rapid processes such as reading.
Dr Tandon said: “Our work is making it clear that most processes — say comprehension or language generation — don’t occur in a single region, but are best understood as very transient states that many separate areas of the brain achieve by very brief, yet critical, interactions.”
The two networks identified play a key role in the reading process. One involves a region of the brain's frontal lobe that sends signals to the temporal lobe, showing progressive activation when a person is building up complex meaning along the length of a sentence.
The second involves another region of the temporal lobe that sends signals to an area of the frontal, allowing understanding of context to enable easier comprehension and processing of each new word read.
The researchers hope that understanding the science behind the highly rapid, complex process of reading will help them learn more about how the brain functions during dyslexia, ultimately guiding treatment options for the reading disorder, which affects approximately 15 per cent of people living in the US.
The research was funded through a five-year, $4.4 million grant from the National Institutes of Health Brain Research Through Advancing Neurotechnologies (Brain) Initiative, which aims to accelerate the development and application of innovative technology to produce a new dynamic picture of the human brain.
