The series of the vastly famous “Harry Potter” fantasy books was the inspiration for scientists to start the first study of brain mapping which is important to identify which parts of the brain are responsible for sub-processes controlling the parsing of sentences, determining the meaning of words and understanding relationships between characters.
The purpose and goal of brain mapping is to advance the understanding of the relationship between structure and function in the human brain. Neuroscientists seek to gain knowledge of the physical processes that underlie human sensation, attention awareness and cognition.
Understanding of stories and processing of words and sentences have long been the main topics of studies across diverse fields of research including computer science, cognitive science, literature, philosophy and linguistics. This new study is a unique because it explains the role of the multiple brain regions that are activated in response to reading.
In order to map the brain, the neuroscientists from Carnegie Mellon University, Machine Learning Department used an integrated computational model of reading that incorporates various subprocesses simultaneously discovering their fMRI (functional magnetic resonance imaging) signatures. fMRI is a technique for measuring and mapping brain activity; it helps to understand how the healthy brain works, besides, is being used in many studies to identify how that normal function is disrupted in disease. This model predicts the fMRI activity associated with reading arbitrary text passages, well enough to distinguish which of two story segments is being read with 74% accuracy.
During the study, researchers asked 9 native English speakers (5 females and 4 males) aged 18-40 years old to read chapter 9 of “Harry Potter and the Sorcerer‘s Stone”. All the subjects had to read using Rapid Serial Visual Presentation (RSVP) technique: the words of the chapter were presented one by one in the center of the screen, the 5000 word chapter was presented over 45 minutes. This procedure showed how a diverse set of information contributes to the neural activity and combined diverse neural encodings into a single prediction of brain-wide fMRI activity over time.
Researchers found a variety of brain regions that encode different information related to story characters. Physical motions of story characters were represented in the posterior temporal cortex/angular gyrus, a region implicated in the perception of biological motion. Processing the motions of the characters also modulated the activity of a region in the superior temporal sulcus, as well as in the left inferior frontal gyrus. The identities of various story characters were expressed in the right posterior superior/middle temporal region, and dialogs among story characters were found to modulate different brain regions – the bilateral temporal and inferior frontal cortices, and language regions. Interestingly, reading character dialogs indicated activity in the right temporo-pariental junction – mind region.
The results of the study suggested that the occipital cortex is responsible for word length, language structure and syntax. Besides, researchers found that the right temporo-pariental cortex is also responsible and important for sentence length and complexity. These brain regions were also modulated by the various syntactic features as well as by the presence of dialog. The authors of study found that all these brain regions are affected by language stimulus, syntax and semantics information as well.
Previous studies analyzed fMRI from human subjects watching a series of short videos where a large set of objects was shown annotated with semantic features; these features were mapped to brain locations, but the study didn‘t include any language stimuli. This study is the first which provided a generative, predictive model of the fMRI neural activity associated with language processing involved in comprehending written stories. This unique study can be used to create single subject maps that may potentially be used to measure reading comprehension and diagnose reading disorders.
The authors of the study say that their findings could be applied in order to improve surgical interventions and their design, as well as in the treatment of psychological and psychiatric disorders.