Cognitive Neuroscience Lecture 11: Language Lecture 1

*L11: Language Guest*
Lecture: Language in the brain—from fundamentals to applications

Language in the brain

Language – A formal system for relating signals and meanings

 • Language
comprehension: signal à
meaning

 • Language
production: meaning à
signal

Language is distinct from speech, thought or communication

Language different from speech:

o
Parrots & computers produce speech but not
language

o
Language communicated via speech or writing

Language different from thought

o
Language verbalizes thought

o
Bi-linguals express same thoughts in different
languages

o
Brain injury may damage language but you can
still think

Language is different from communication

o
Body language, math

Language Knowledge

Innate

o
Critical periods: exposure during limited time
in development (adolescence) is critical for normal devàprocess with its own “clock”

§
Children not exposed before adolescence fail to
acquire it later

§
2nd language harder when learned
after adolescence

o
Genetically linked to language deficits

§
Developmental language disorders not due to
evident neural injury

2 sources of our language knowledge

o
Genetic blueprint (innate neural/cognitive
machinery)

§
Explains aspects of language that are the same
across languages (universal grammar)

o
Learning

§
Allows us to learn characteristics of specific
language one is exposed to

·
Explains aspects of language that are different
across languages

Language is productive

o
Understand and produce infinite number of
sentences never produced or heard before

o
How?

§
System of rules (grammar) for combining elements
(words)

o
Rule system

§
Allows for sentences to be understood and
produced similarly across ppl

§
Everyone has same definition for gramattical vs
non

Language is multi-componential

o
Multiple components specialized for processing
different aspects of language knowledge

§
Semantics: word meanings

§
Syntax: word ordering

§
Phonology: word sounds

o
Components used in comprehension and production
of language

o
Patterns of language ability and disability
subsequent to neural injury

o
**Aphasia**:
language impairment

o
Cases exhibit full range of double dissoc

§
phonology vs semantics

§
syntax vs semantics

Phonology: knowledge of language sounds

**phonemes**:
smallest unit sound that distinguishes one word from another in a given
language

o
po**t**/po**d**

**Phonological**
words (morphemes)**: combinations of sounds that comprise meaningful units**

o
Giraffe-s à2

o
Un-happi-nessà3

Semantics: word meaning

o
Semantics: our knowledge of the meanings of
words that allows us to use and understand them appropriately

§
More complex than dictionary def

o
Sweep vs. swept

Syntax: rules

o
Knowledge of how words can be combined in
ordered to express meaning

o
English = SVO

Language network: overview

Fmri conditions: spoken and written stories vs.
scrambled spoken/written stim

Perisylvian language areas

o   Frontal lobe: inferior frontal
gyrus

o   Temporal lobe: superior and
middle temporal gyri

o   Parietal lobe: supra-marginal
and angular gyri

o
Broca’s area: BA 44/45

o
Wernicke’s area: BA 22

o

Language Lateralization: is it limited to left
hem?

o
Neuroanatomical asymmetries

§
Planum temporale: auditory processing region
within Sylvian fissure

§
LH larger than RH in most right-handers (starts
at 31st week of gestation)

§

o
How are the language functions distributed
across hemispheres?

o
How can we find out?

§
Isolate the hemis

§
WADA

§
Commisurotomy

·
Separate hemis by cutting corpus callosum

·
Treats intractable epilepsy

·
Test hemis separately with 1 vis field
presentation

§
Hemispherectomy

·
Surgical treatment for tumors and rasmussen’s
syndrome

·
Affects RH or LH

Right Hemisphere Language?

o
Limited and redundant (not necessary)

o
Hemi differences between comprehension and
production

§
Left: production

§
Right: comprehension

o
Good recovery in response to early damage

§
Early damage shows right hemi’s latent language
capacities

o
Difference in neuroimaging and lesion studies in
terms of right hemi involvement?

§
Lesion studies reveal necessary neural
substrates (but not sufficient)

Phonological aspects of language processing:

Ventral: Comprehension: AudàSTGàMTG/ITGàATL

Dorsal: Production: STGàSptàSMGàIFG+PM

Ventral stream damage

Intact environmental sound identification,
visual recognition, semantic knowledge

Impaired speech comprehension (discrim, ID,
repetition of word he just heard, comprehension)

o
Phoneme ID difficult

o
Phonological word id difficult

Dorsal stream damage

Trouble with phon. Word selection, phoneme
selection, motor planning

Evidence from defecits affecting semantic categories

Lesion locations associated with selective
deficits in naming words from specific categories (people, animals, tools)

o
Left middle and inferior temporal gyri

Evidence from voxel based morphometry

o
Semantic dementia

§
Degenerative disease: loss of understanding of
word meanings

§
Cortical atrophy

o
Mummery et al:

§
VBM measures cortical thickness at each voxel

·
Atrophy left lateralized in anterior temporal
lobe (temporal pole)

Using ERP to examine syntactic processing

How could we isolate syntactic processing in
neuroimaging/disruption studies?

o
Grammatical vs. ungrammatical sentences

o
More complex vs. less complex

o
Syntax but no semantics (jabberwocky)

Left anterior negativity characteristic ERP
response after syntactic violation

Distribution over time and electrodes of
differences in brain response to grammatical vs. ungrammatical word

o
LAN at 450-500ms

o
Early and later ERP identified at left anterior
electrodes (**left frontal cortex**)

fMRI: sentences with and without meaning

Jabberwocky compared to just lists of nonword

Left IFG consistently associated w/ lesions
affecting syntactic processing and activation studies

Other perisylvian language areas also associated
w/ syntactic processing

Conclusions?

o
H1: Syntactic processing distributed

o
H2: we have not yet figured out how to isolate
syntax from other aspects of language processing

Language network

Basic language processes

Neural substrates

Methods and results