Language

Mental Lexicon

How words and information are organized as semantic networks

• Similar words get grouped together & includes other information

Morphological

Word form/parts

Semantic

Concepts/Meaning

Syntactic

Rules/Grammar

Lexical Decision Tasks

Shows that you are faster to decide if two words are real words if they're semantically related > not related

Semantic Network Theory - Spreading Activation

Activity at one node goes to other nodes through links

• Fast & Automatic

• Decreased in proportion to distance travelled

Rapid Integration

Knowing the meaning of words based on contexts surrounding them

Aphasia or Dysphasia

Disorder of language, effecting communication, caused by brain damage, & independent of general cognitive ability (memory, attention, etc.)

Signs of Aphasia

• Loss in ability to express/produce speech

• ^ includes ability to write properly, sometimes includes reading too

• Loss of ability to comprehend speech and writing

The Classical Picture (Now Outdated)

• Broca's Area = Language Production (Speech)

• Wernicke's Area = Comprehension

The Changing Picture (additional information)

• Broca's Area = Syntax

• Lesion Studies --> Individual Differences

The Emerging Picture

• From Wernicke's area to the temporal lobe circuit

• From Broca's Area to Broca's Complex

Left Perisylvian Language Network

• Includes Broca’s, Wernicke’s, and Sylvian Fissure Areas

• Processing language

Broca’s Aphasia

• Lesions in left inferior frontal region (Brodmann’s Area 44 & 45)

• Nonfluent, labored, hesitant speech

• Anomia

• Simple language comprehension intact

• Partial Paralysis to one side of body (Hemiplegia)

• Not much recovery over time

Anomia

Loss of ability to name persons or subjects

Wernicke’s Aphasia

• Lesions in posterior left superior temporal gyrus, extending to parietal cortex (Brodmann Areas 22 & 30)

• Fluent speech, but lots of paraphasia (“bread” = “cake”)

• Syntactical structure is good, meaningless sentences

• Can’t repeat words or sentences, can’t understand what they read or hear

• No partial paralysis

Wernicke-Lichtheim (Geschwind) Model [No longer useful]

• Broca’s Area: Production

• Wernicke’s Area: Perception, memory for words

• Connected by Arcuate Fasciculus

Overall Broca’s Aphasia

• Syntactic Deficit

• + Production problems

Methods of Observing Syntactic Processing

• STG Lesion Summary

• PET Imaging

• fMRI

fMRI Study for Syntactic Processing

Utilize complex syntax in the form of reversible passives

N400 Modulation

Larger when meaning of word is not predictable in the context

Embodied Semantics

Symbols & words are tied to representation outside language system

• “Apple” is tied to our experiencing, seeing, hearing, and tasting apples

ATL - Anterior Temporal Gyrus

Hub where info of all modalities is integrated

Networks for Language Comprehension and Production

• Superior Longitudinal jasciculus

• Uncinate fasciculus

Arcuate fasciculus

Long fiber tract between Broca’s & Wernicke’s Area

Left Hemisphere

• Supports Speech

• Word-finding

• Grammar

• Comprehension

• Conceptual

Right Hemisphere

• Supports pragmatics

• Discourse

• Metaphors

• Jokes/Puns

• Prosody (sound infliction)

Left Hemisphere Symmetry to Right Brain

Left is anatomically bigger is most areas

LH in Speech

Produces speech

RH in speech

some basic language comprehension

Used to look at fiber tracks in speech

DTI Tractography

Local Phrase Structure Building

Ventral pathway

• From frontal to anterior temporal lobe

Semantics

Ventral Pathway starting from Broca’s Area 45

• Capsule to temporal lobe anterior to primary auditory cortex

Syntax

Dorsal Pathway starting from Broca’s Area 44

• Pars opercularis to posterior-superior temporal gyrus

Two Dorsal Pathways

• One connects to pre-motor Cortex (PMC) (speech)

• Other connects area 44 w/ STG (syntax)

Two Ventral Pathways

Connect temporal lobes to inferior frontal cortex like area 45 (semantics)