Language and the Brain
This area studies how the brain represents and processes language, drawing on patterns of impairment after damage and on measures of brain activity during language use.
Definition
The branch of psycholinguistics, overlapping with neurolinguistics, concerned with the neural representation and processing of language in the human brain.
Scope
It covers the classical aphasia syndromes and the lesion-based models that grew from them, contemporary neuroimaging and electrophysiological findings on the cortical networks supporting comprehension and production, the dual-stream organization of speech processing, hemispheric lateralization, and how multiple languages are organized in the brain. It describes the neuroscience of language as a domain of inquiry and is not a guide to diagnosing or treating language disorders.
Sub-topics
Core questions
- Which brain regions and networks support comprehension and production?
- What do aphasic syndromes reveal about the functional organization of language?
- How are speech and language processed across the brain's two streams and hemispheres?
- What do electrophysiological responses such as the N400 tell us about real-time processing?
Key concepts
- Broca's area
- Wernicke's area
- aphasia
- dual-stream model
- N400
- hemispheric lateralization
Key theories
- Classical (Wernicke-Lichtheim-Geschwind) model
- A lesion-based model locating speech production around Broca's area and comprehension around Wernicke's area, connected by the arcuate fasciculus, used to explain the classical aphasia syndromes.
- Dual-stream model of speech processing
- Hickok and Poeppel's account distinguishing a ventral stream mapping sound to meaning and a dorsal stream mapping sound to articulation, replacing the strictly localizationist classical picture.
- The N400 and semantic integration
- Kutas and Hillyard's discovery of a negative event-related potential peaking around 400 ms that is larger for semantically anomalous words, providing an electrophysiological index of meaning processing.
History
The neuroscience of language began with nineteenth-century lesion studies by Broca and Wernicke, synthesized by Geschwind into the classical connectionist model. The advent of event-related potentials (notably the N400 in 1980) and functional neuroimaging shifted the field toward distributed network accounts such as the dual-stream model.
Debates
- Localization versus distributed networks
- Whether language functions are tied to discrete cortical centers, as in the classical model, or supported by broadly distributed and partly bilateral networks, as neuroimaging and dual-stream accounts suggest.
Key figures
- Norman Geschwind
- Gregory Hickok
- David Poeppel
- Marta Kutas
- Steven Hillyard
Related topics
Seminal works
- geschwind1970
- hickokpoeppel2007
- kutashillyard1980
Frequently asked questions
- Is language located only in the left hemisphere?
- Language is left-lateralized in most people, especially for grammar and speech production, but the right hemisphere contributes to aspects such as prosody and discourse, and lateralization varies across individuals.
- What is aphasia?
- Aphasia is an acquired impairment of language caused by brain damage, typically from stroke; its different forms (such as Broca's and Wernicke's aphasia) have historically informed models of how language is organized in the brain.