Neurobiology of Language

Broca and Wernickes area

broca damage to posterior inferior frontal gyrus in lh

wernicke damage to superior temporal gyrus in lh

classical model of language

speech input→ superior temporal gyrus→ inferior frontal gyrus → motor output

Tremblay and Dick 2016

arcuate fasciculus was seen as connection between broca and wernickes area

oversimplification- language in dorsal and ventral pathways

current model of language in the brain Price 2012

inferior frontal gyrus, superior temporal sulcus, middle and inferior temporal gyri, angular gyrus, prefrontal and premotor cortex

dorsal stream used when repeating words

ventral stream used to understand meaning

spectogram

time x frequency, darkness= loudness

used to visualise speech signal to understand properties

hierarchical processing of simple non speech sounds Wessinger et al 2001

primary auditory cortex responds to simple tones

stg respond to only complex noises- recognises phonetic features

sts meaning

speech comprehension region Scott et al 2000

anterior superior temporal gyrus/suclus active when we understand speech compared to unintelligible speech

motor cortex Hervais Adelman et al 2012

we activate the primary motor cortex when perception is difficult= use what we know about how to produce speech to understand

Dual stream models of spoken language: Rauschecker and Scott 2009

ventral stream- maps sound to meaning

dorsal stream- maps sound to action

word boundaries Zhang et al 2026

STG drops in activity at word boundaries

approaches to experiments

silent speech production- activation in IFG, motor cortex, cerebellum

overt speech production- fmri sensitive to movement so scanner records for silence then stops then ppt speaks word then scanner starts (sparse temporal sampling)

modulating auditory feedback- ppt speaks into microphone and hears voice delayed= stutter or slow down as not in line with prediction of immediate sound, when ppts pitch manipulated ppts adjusted to compensate

posterior superior temporal gyrus

motor command and prediction of how word will sound sent to stg

prediction compared with ongoing speech

error signal sent to motor cortex to adjust articulation

higher activity in stg when we listen to recording of speech than real time, higher when recording is adjusted