Summary: Language, a cornerstone of human connection, finds its intricate roots deep within the human brain. Researchers unveil this with a sweeping meta-analysis of over 400 neuroscientific experiments.
Beyond just the classical language regions in the left hemisphere, surprising players emerge: the cerebellum, structures below the cerebral cortex, and even the emotion-tied right amygdala. These findings could revolutionize understanding and treatments for language recovery post-brain injury.
The meta-analysis synthesized over 400 neuroscientific experiments involving more than 7000 subjects.
In addition to known language regions, structures in the cerebellum and below the cerebral cortex play essential roles in language processes.
Phonetic patterns, crucial for emotional meaning, activate the right amygdala, which links emotion and memory.
Source: Leipzig University
Language is the most important tool for human communication and essential for life in our society.
“Despite a great deal of neuroscientific research on the representation of language, little is known about the organisation of language in the human brain. Much of what we do know comes from single studies with small numbers of subjects and has not been confirmed in follow-up studies,” says Dr Sabrina Turker from the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig. This meta-analysis aims to help change that.
Based on more than 400 neuroscientific experiments using functional imaging and involving more than 7000 subjects, the analysis provides in-depth insights into how the brain organises language.
A quantitative, coordinate-based meta-analysis was used to integrate the many findings from different studies in the most complete and objective way possible. This makes it possible to see where the brain is activated when particular language processes occur. This approach provides insights into fundamental principles of how the brain organises language processing.
The researchers not only studied language as a process in general, but also explicitly addressed subordinate processes: the meaning of language at the level of words and sentences (semantics); the phonetic structure of language (phonology); grammar and the arrangement of linguistic elements (syntax); and the phonetic structure of language at sentence level, including melody, intonation and rhythm (prosody).
In addition to the classical language regions in the left hemisphere of the brain, the authors of the study found that structures in the brain regions below the cerebral cortex and the cerebellum play a key role in language processes.
“These regions have been rather neglected in previous neuroscientific research on language,” says Gesa Hartwigsen, Professor of Cognitive and Biological Psychology at Leipzig University.
“In particular, the left and right cerebellum are involved in processes related to the meaning of language and the processing of sounds. Similarly, phonetic patterns that transcend individual words and also convey emotional meaning are associated with activation in the right amygdala, a paired core area of the brain.”
She points out that this part influences emotion and memory.
Professor Gesa Hartwigsen adds: “Our findings may serve future studies involving language recovery after brain injury, for example caused by stroke. And they could help to refine models of language processing.”
About this language processing and brain mapping research news
Cortical, Subcortical, and Cerebellar Contributions to Language Processing: A Meta-Analytic Review of 403 Neuroimaging Experiments
Language is a key human faculty for communication and interaction that provides invaluable insight into the human mind. Previous work has dissected different linguistic operations, but the large-scale brain networks involved in language processing are still not fully uncovered.
Particularly, little is known about the subdomain-specific engagement of brain areas during semantic, syntactic, phonological, and prosodic processing and the role of subcortical and cerebellar areas. Here, we present the largest coordinate-based meta-analysis of language processing including 403 experiments.
Overall, language processing primarily engaged bilateral fronto-temporal cortices, with the highest activation likelihood in the left posterior inferior frontal gyrus (IFG). Whereas we could not detect any syntax-specific regions, semantics specifically engaged left posterior temporal areas (left fusiform and occipitotemporal cortex) and the left frontal pole.
Phonology showed highest subdomain-specificity in bilateral auditory and left postcentral regions, whereas prosody engaged specifically the right amygdala and the right IFG. Across all subdomains and modalities, we found strong bilateral subcortical and cerebellar contributions.
Especially the right cerebellum was engaged during various processes, including speech production, visual, and phonological tasks. Collectively, our results emphasize consistent recruitment and high functional modularity for general language processing in bilateral domain-specific (temporo-frontal) and domain-general (medial frontal/anterior cingulate cortex) regions but also a high specialization of different subareas for different linguistic subdomains.
Our findings refine current neurobiological models of language by adding novel insight into the general sensitivity of the language network and subdomain-specific functions of different brain areas and highlighting the role of subcortical and cerebellar regions for different language operations.