Language and the brain Rajeev Raizada Dept of

Language and the brain Rajeev Raizada Dept. of Brain & Cognitive Sciences rajeev. raizada@gmail. com raizadalab. org

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Language and the brain: why bother with brain stuff in the first place? Key language areas, and lesion deficits Lots of interactive brain areas • It’s not just a couple of areas on the left Interpreting brain activation: • Who cares which bit of the brain lights up? • We want brain imaging to tell us about linguistic information processing, or linguistic representations 4

Language areas in the brain Some brain areas are specialised for language • • Broca's area: speech production Wernicke's area: speech perception On the left side of the brain (in 95% of people) This is pretty much the only left-brain / right-brain saying that is actually true What does "specialised for language" actually mean? • • If you lose these areas, you lose language When you use language, you use those areas BUT: That does not mean that they only do language E. g. Broca's area may be involved in music perception

Broca's area: crucial for speech production Paul Broca (1861): patient "Tan" • Severe deficit in speech production: could only say "tan" • Good language comprehension Tan's brain: lesion (injury) in left frontal cortex

Auditory cortex and Wernicke's area Auditory cortex: all sounds pass into here • • Mostly specialised for low-level features, e. g. raw frequency Bilateral (on both left and right sides of the brain) Wernicke's area (Carl Wernicke, 1874) • • Patient with very poor speech comprehension Good speech production Lesion on left side, just behind auditory cortex Specialised for processing "higher level" sounds: speech

Auditory cortex and Wernicke's area From http: //www. physiology. wisc. edu/neuro 524/

Language areas in the brain From University of Washington's Digital Anatomist project

An example of Broca's aphasia in the news: Gabby Giffords http: //www. youtube. com/watch? v=rx 3 nf. UKvr. Z 8 Start at 2 mins

Wernicke's aphasia Deficit of comprehension, not production. Fluent speech, but lacking coherent meaning https: //www. youtube. com/watch? v=a. Vh. YN 7 NTIKU

There's more to language in the brain than just Broca's and Wernicke's Friederici, A. D. (2012). The cortical language circuit: from auditory perception to sentence comprehension. Trends in cognitive sciences, 16(5), 262 -268. 12

The claim "language is on the left" is a total over-simplification Specht, K. (2013). Mapping a lateralization gradient within the ventral stream for auditory speech perception. Frontiers in human neuroscience, 7. 13

The claim "language is on the left" is a total over-simplification Peelle, J. E. (2012). The hemispheric lateralization of speech processing depends on what "speech" is: a hierarchical perspective. Frontiers in human neuroscience, 6. 14