1. Language Why language is hard to study
Aphasia classification: which patterns of deficits run together?
Older vs. Newer Models of Language Organization
Language re-organization following early injury

2. What is language Many animals use simple sounds for communication
What is line between simple communication and language?
What makes human language unique?
Use of word as referents for things or ideas
ordering of words in different ways to alter meaning

3. What is required for language?
Interaction of memory with sensory input and motor output systems
Memory
Phonological
Orthographic
semantic
Sensory
Auditory processing
Visual processing
Tactile processing (braille)
Motor
articulation, writing, signing or drawing

4. Components of language
Phoneme: individual sound units
Grapheme: the written form used to represent phoneme(s)
Morphemes: smallest meaningful units of a word, in combination creates words
Syntax: admissible combinations of words in phrases and sentences (grammar)
Lexicon: the collection of all words in a given language, mental “dictionary”
Semantics: the meanings that correspond to all lexical items and possible sentences

5. Components of language
Morphology: study of how and why words take on certain structure and how that affects semantics and syntax
Pragmatics: social rules governing how language is used
Prosody: vocal intonation that can modify the literal meaning of words and sentences
Discourse: linking of sentences such that they constitute a narrative

6. Language and the brain: functional segregation?
Syntax
Speaker Identity
Phrases
Prosody
Words
Morphemes
Meaning
Intent
Phonemes

7. The Challenge of Language Research
Unique human ability
animal communication systems have more limited combinatorial repertoire
limits study of brain behavior relationships to humans
There are no adequate animal models of language
Makes completely controlled experiments impossible
Purposeful lesion studies are obviously unethical
The closest approximation is birdsong, but
Vocalizations of birds are significantly less complex
Many structures within the human brain do not have homologues in the avian brain

8. Aphasia: Window into the organization of language function
The left hemisphere of Paul Broca’s patient “Tan”

9. Paul Broca- localization of language production
Early work on aphasia
Paul Broca- localization of language production
Broca’s aphasia, motor, expressive, or non-fluent aphasia
Difficulty speaking : slow, deliberate, simple grammar structure, “telegraphic”
Melodically flat
Comprehension intact
Damage to left frontal (lower posterior)

10. Examples of Broca’s Aphasia

11. Carl Wernicke- localization of language comprehension
Early work on aphasia
Carl Wernicke- localization of language comprehension
Wernicke’s aphasia, receptive, fluent aphasia
Speech production is intact
Speech flows without hesitation
Appropriate intonation
Comprehension impaired
Speech is “meaningless”
Damage to left temporal (superior and posterior)

12. Examples of Wernicke’s Aphasia

13. Classical Aphasia Syndromes
Fluent Speech?
YES NO
Intact
Comprehension?
YES NO
YES NO
Intact
Repetition?
YES NO
YES NO
YES NO
YES NO
Anomic
Conduction
Trans-
Cortical
Sensory
Wernicke
Trans-
Cortical
Motor
Broca
Mixed
Trans-
Cortical
Global

14. Damage Associated with Common Aphasic Syndromes
Wernicke
Broca
Global
Conduction

15. Pure Aphasias Alexia without agraphia Agraphia Word deafness
Normal speech, normal writing, poor reading
Agraphia
Normal speech, poor writing
Word deafness
Normal speech, poor comprehension, poor repetition

16. Clinical Assessment of Aphasia
Subtests of the Boston Diagnostic Aphasia Exam:
Boston Naming Test- patient required to name various pictures that vary in terms of frequency, animacy, etc…
Responsive naming- “what do we tell time with?” and “what color is grass?”

17. Boston Naming Errors ‘water bird in Florida’
Type
Circumlocution
Perceptual
Semantic
Paraphasia
Phonemic
Neologism
Aphasia
Syndrome
Anomic
Wernicke and
Transcortical
Sensory
‘water bird in Florida’
‘thing you lie in in summer’
‘rough skin, from Africa’
‘helmet’
‘fishing net’
‘pig’
‘duck’
‘bed’
‘elephant’
‘pemlican’
‘hannock’
‘rhisocerus’
‘palifrene’
‘habiteller’
‘cantifron’

18. Tests of Expression Subtests of the BDAE: Oral Agility Verbal Agility
Automatic Sequences
Mean length of utterance

19. Tests of comprehension
Subtests of the BDAE:
Basic word discrimination
Commands
Complex ideational material

20. Tests of repetition Subtests of the BDAE: Single word repetition
Single pseudoword repetition
Repetition of sentences

21. BDAE Profiles
Broca’s
Wernicke’s

22. The Wernicke-Geschwind (neurological) model

23. Limitations of Classical Approach
Based on observations of (mostly) acute stroke patients
Up to 49% of aphasics are unclassifiable
Broca’s aphasics have trouble understanding syntax in non-standard word order
Does not account for complexities of normal language processing and other dissociations

24. Limitations of lesion studies I
Lesions are often extensive and may damage connection fibers
No two lesions (or patterns of behavioral impairment) are exactly alike, making comparisons across subjects inherently imprecise
Due to the structure of the vasculature, some areas are never selectively damaged by stroke

25. Limitations of lesion studies II
We do not yet fully understand mechanisms of plasticity following damage to the brain
Patients may have adopted compensatory strategies, so their behavioral performance is not truly reflective of their cognitive deficit 25

26. Psycholinguistic Models
Explain normal language processing
Account for broader range of language deficits
Less constrained by anatomic considerations
Price, 2000

27. Dyslexia Double Dissociation
Dyslexia Subtype
‘LONT’
‘DEBT’
System Preserved
Surface
Intact
Impaired
Phonologic
Orthographic
Price, 2000

28. Plasticity and Re-Organization of Language

29. Definitions
Structural plasticity- physiological changes in a given area of the brain in response to learning, injury, or development
Functional plasticity- cortical reorganization in response to learning, injury, or development(i.e., the ability of one area of the brain to assume the functional role of another).

30. Evidence for structural plasticity
Mechelli et al., 2004

31. Language Transfers During, but not After Early Critical Period
Speech After Hemispherectomy
Age when Lesion Acquired
Unaffected or Improved
Permanent Aphasia
Side of Hemispherectomy
Before Teens LEFT 49 3
RIGHT 38 5
Adulthood LEFT 6 25
Basser, 1962 (cited in Lenneberg, 1967)

32. Transfer of Speech in Left Hemisphere Epilepsy (n=396)
Speech Representation
Determined by Wada Test (n/%)
Age at Injury/Onset
TOTAL
Left
Bilateral
Right
≤ 5 years old
134
60 (45)
20 (15)
54 (40)
> 5 years old
262
220 (84)
18 (7)
24 (9)
Rasmussen & Milner, 1977

33. When language develops in the right hemisphere -
Are language functions supported by the same (homologous), or by different networks?
Do some language functions transfer more so than others?

34. Tivarus, 2012

35. ‘Mirror Image’ Organization after Early Left Injury
Differences in
Dominant Activation
‘Mirror Image’ Organization after Early Left Injury
Areas activated during DN vs. Sound Identification
Tivarus, 2012