Language Disorders

Medical and Psychosocial Aspects of Disability

11/2/04

Communication

There are 3 elements in this exchange, and all must be present:1. Message

2. Message must be expressed

3. Message must be understood

Speech and Language

Speech is the motor act of communicating by articulating verbal expression

Language is the knowledge of a symbol system used for interpersonal communication.

Four domains of language

PhonologyGrammarSemanticsPragmatics

Phonology

The ability to produce and discriminate the specific sounds of a given language.

Its unit, the phoneme, is characterized by distinctive features.

Babies start discriminating phonemes during the first few months of life, and they produce them soon after.

Phonology

Phonological receptivity is pluripotential at birth

Starts to decay at around 10 months Reaches a rather general inability to

acquire native phonology by preadolescence

Grammar

The underlying rules that organize any specific language.

The combinatorial rules that most native speakers of a language recognize as acceptable for that language and that allow a native speaker an infinite array of generative possibilities.

Grammar

Composed of both morphology and syntax.

Semantics

The study of meaning Includes the study of vocabulary

(lexicon).

Lexicon

Lexical entries are organized in the mental dictionary according to well-defined rules

Allows the young child to acquire a peak average of 10 new words per day.

By 24 months the average child knows 50 words.

Lexicon Growth

The subsequent exponential growth makes it difficult to determine vocabulary size with exactitude.

Environmental factors predicting large vocabularies Reading and discussing children's stories The quality of dinner table conversations Large mother-produced number of words Higher socioeconomic status (SES) Being the firstborn ( Hoff-Ginsberg, 1998 ) Quantity and sophistication of mother's

vocabulary ( Snow, 1998 ).

Pragmatics

A number of sub-domains reflecting communicative competence.

Sub domains of Pragmatics

Rules of conversation (turn-taking, topic maintenance, conversational repair)

Politeness Narrative and extended discourse The implementation of communicative

intents

Pragmatic disorders

Little variety in language use May say inappropriate or unrelated

things during conversations May tell stories in a disorganized way Can often make demands, ask

questions, and greet people Has trouble organizing language to talk

about what happened in the past.

Pragmatic disorders

Appear to pull topics out of the air May not use statements that signal a

change in topic, such as "That reminds me."

Peers may avoid having conversations with such a child.

Can lower social acceptance.

Language Developmental Trajectory

Canonical Babbling

Word comprehension

Word production

Word combinations

Telegraphic speech

By age 3, most normal children have mastered the basic structures of their native language

Language acquisition

Occurs with uniformity and rapidity Supports the hypothesized existence of

innate, genetically determined Universal Grammars

Recently proposed a combination of traditional learning and innate language modules.

Disfluencies in Children

Almost all children go through a stage of frequent disfluency usually between the ages of 2 and 5.

Speech is produced easily in spite of the disfluencies.

Etiology of Speech & Language Disorders Mental retardation Hearing loss Maturation delay

(developmental language delay)

Expressive language disorder (developmental expressive aphasia)

Bilingualism Psychosocial

deprivation Autism Elective mutism Receptive aphasia Cerebral palsy

Overview of major types of speech disordersspeech disorders

Definitions vary, but generally agree that speech disorders involve deviations of sufficient magnitude to interfere with communication.

They draw attention to the speaking act and away from the message

1. Fluency Disorders

Speech is characterized by repeated interruptions, hesitations, or repetitions

Stuttering is by far the most well-known fluency disorder

1. Fluency disorders - Stuttering Flow of speech is abnormally

interrupted by repetitions, blocking, or prolongations of sounds, syllables, words, or phrases

Very familiar, but actually quite rare – only 1-5% of the population.

Articulation disorders actually occur much more frequently than stuttering

Stuttering -- Causes

Still a mystery Three perspectives:

1. Symptom of emotional disturbance

2. Result of biological makeup

3. Learned response

Stuttering

Disorder of speech fluency that interrupts the forward flow of speech. All individuals are disfluent at times Differentiated by the kind and amount of

the disfluencies

Characteristics-Repetition

Sounds b-b-b-ball

Syllables mo-mo-mommy

Parts of words basket-basket-basketball

Whole words, and phrases

Characteristics-Prolongation Stretching, of sounds or syllables

r-----abbit

Characteristics

Tense pauses, hesitations, and/or no sound between words

Speech that occurs in spurts as the child tries to initiate or maintain

voice

Variability in stuttering behavior depending on the speaking situation

Related behaviors

tense muscles in the lips, jaw, and/or neck

tremor of the lips, jaw, and/or tongue foot tapping eye blinks head turns

2. Articulation disorders

This is the largest category of all speech problems

DSM-IV calls these “phonological disorders.”

“abnormal speech-sound production, characterized by inaccurate or otherwise inappropriate execution of speaking”

2. Articulation disorders

Great majority are functional articulation disorders

Might represent as much as 80% of the speech disorders diagnosed by speech clinicians

Must be very careful to distinguish true problems from delay.

E.g., r, s, th problems may largely disappear naturally after 5 years of age

2. Articulation disorders

1. Omissions

2. Substitutions

3. Additions

4. Distortions

3. Voice disorders

Unusual or abnormal acoustical qualities in the sounds made when a person speaks

Very little research here What is a “normal” sounding voice? Nasality, hoarseness, breathiness

Normal Speech Development

4. Delayed speech

Failure to develop speech at the expected age

Somewhat subjective Usually associated with other

maturational delays May also be associated with a hearing

impairment, mental retardation, emotional disturbance, or brain injury

Often the result of environmental deprivation

Epidemiology of Speech Delay Common childhood problem Affects 3 to 10 percent of children. 3-4X more common in boys than in

girls.

Most common causes of speech delay

Mental retardationHearing lossMaturation delay

Overview of major types of language disorderslanguage disorders Need to understand normal language

and prelanguage development See Table 10.1 on 320 May involve comprehension

(understanding) or expression in written or spoken language

These are very complex to diagnose and treat

Language and Brain

Language disordersLanguage disorders

1. Expressive language disorders

2. Receptive language disorders

3. Aphasia – loss of the ability to speak or comprehend language because of an injury or developmental abnormality in the brain

EXPRESSIVE LANGUAGE DISORDER

(developmental expressive aphasia)

Fail to develop the use of speech at the usual age.

EXPRESSIVE LANGUAGE DISORDER

Normal intelligence Normal hearing Good emotional relationships Normal articulation skills. Comprehension of speech is

appropriate to the age of the child

EXPRESSIVE LANGUAGE DISORDER

Brain dysfunction that results in an inability to translate ideas into speech.

EXPRESSIVE LANGUAGE DISORDER

The child is at risk for language-based learning disabilities (dyslexia).

May use gestures to supplement their limited verbal expression .

Maturation Delay vs. Expressive Language Disorder? The late bloomer will

eventually develop normal speech

The child with an expressive language disorder will not do so without intervention.

Maturation Delay vs. Expressive Language Disorder?

It is sometimes difficult, if not impossible, to distinguish at an early age a late bloomer from a child with an expressive language disorder.

BILINGUALISM

A bilingual home environment may cause an apparent temporary delay in the onset of both languages.

BILINGUALISM

The bilingual child's comprehension of the two languages is normal for a child of the same age.

Usually becomes proficient in both languages before the age of five years.

Interference or transfer

An English error due to the direct influence of the primary language structure.

This is a normal phenomenon

Silent period

Common second-language acquisition phenomenon

Often very quiet, speaking little Focus on understanding the new

language The younger the child, the longer the

silent period tends to last.

Code switching

Changing languages over phrases or sentences.

Normal phenomenon

Benefits of Bilingualism

Children who are fluent bilinguals actually outperform monolingual speakers on tests of metalinguistic skill.

Benefits of Bilingualism

Our world is shrinking and business becomes increasingly international

Children who are fluent bilingual speakers are potentially a tremendously valuable resource for the U.S. economy.

Language Disorders

Egyptians reported speech loss after blow to head 3000 years ago

Broca (1861) finds damage to left inferior frontal region (Broca’s area) of a language impaired patient, in postmortem analysis

Language Disorders (2)

In language disorders 90-95% of cases, damage is to the left

hemisphere 5-10% of cases, to the right hemisphere

Wada test is used to determine the hemispheric dominance Sodium amydal is injected to the carotid artery First to the left and then to the right

Language Disorders (3) Paraphasia:

Substitution of a word by a sound, an incorrect word, or an unintended word

Neologism: Paraphasia with a completely novel word

Nonfluent speech: Talking with considerable effort

Agraphia: Impairment in writing

Alexia: Disturbances in reading

Three major types of AphasiaRosenzweig: Table 19.1, p. 615

Borca’s aphasia Nonfluent speech

Wernicke’s aphasia Fluent speech but unintelligible

Global aphasia Total loss of language

Others: Conduction, Subcortical, Transcortical Motor/Sensory (see also Kandel, Table 59-1)

Brain areas involved in Language

Broca’s AphasiaBrodmann 44, 45

Lesions in the left inferior frontal region (Broca’s area)

Nonfluent, labored, and hesitant speech Most also lost the ability to name persons or

subjects (anomia) Can utter automatic speech (“hello”) Comprehension relatively intact Most also have partial paralysis of one side of

the body (hemiplegia) If extensive, not much recovery over time

Wernicke’s AphasiaBrodmann 22, 30 Lesions in posterior of the left superior temporal

gyrus, extending to adjacent parietal cortex Fluent speech But contains many paraphasias

“girl”-“curl”, “bread”-“cake” Syntactical but empty sentences Cannot repeat words or sentences Unable to understand what they read or hear Usually no partial paralysis

Wernicke-Geschwind Model1. Repeating a spoken word

Arcuate fasciculus is the bridge from the Wernicke’s area to the Broca’s area

Wernicke-Geschwind Model2. Repeating a written word

Angular gyrus is the gateway from visual cortex to Wernicke’s area

This is an oversimplification of the issue: not all patients show such predicted behavior (Howard, 1997)

Sign Languages

Full-fledged languages, created by hearing- impaired people (not by Linguists): Dialects, jokes, poems, etc. Do not resemble the spoken language of the same

area (ASL resembles Bantu and Navaho) Pinker: Nicaraguan Sign Language Another evidence of the origins of language (gestures)

Most gestures in ASL are with right-hand, or else both hands (left hemisphere dominance)

Signers with brain damage to similar regions show aphasia as well

Signer Aphasia

Young man, both spoken and sign language: Accident and damage to brain Both spoken and sign languages are affected

Deaf-mute person, sign language: Stroke and damage to left-side of the brain Impairment in sign language

3 deaf signers: Different damages to the brain with different

impairments to grammar and word production

Spoken and Sign Languages

Neural mechanisms are similar fMRI studies show similar activations for

both hearing and deaf But in signers, homologous activation

on the right hemisphere is unanswered yet

Dyslexia

Problem in learning to read Common in boys and left-handed High IQ, so related with language only Postmortem observation revealed anomalies

in the arrangement of cortical cells Micropolygyria: excessive cortical folding Ectopias: nests of extra cells in unusual location

Might have occurred in mid-gestation, during cell migration period

Acquired Dyslexia = Alexia Disorder in adulthood as a result of disease

or injury Deep dyslexia (pays attn. to wholes):

“cow” -> “horse”, cannot read abstract words Fails to see small differences (do not read each

letter) Problems with nonsense words

Surface dyslexia (pays attn. to details): Nonsense words are fine

Suggests 2 different systems: One focused on the meanings of whole words The other on the sounds of words

Electrical Stimulation

Penfield and Roberts (1959): During epilepsy surgery under local anesthesia to locate cortical language areas, stimulation of: Large anterior zone:

stops speech Both anterior and posterior temporoparietal cortex:

misnaming, impaired imitation of words Broca’s area:

unable comprehend auditory and visual semantic material, inability to follow oral commands, point to objects, and

understand written questions

Studies by Ojemann et al. Stimulation of the brain of an English-

Spanish bilingual shows different areas for each language

Stim of inferior premotor frontal cortex: Arrests speech, impairs all facial movements

Stim of areas in inferior, frontal, temporal, parietal cortex: Impairs sequential facial movements, phoneme

identification Stim of other areas:

lead to memory errors and reading errors Stim of thalamus during verbal input:

increased accuracy of subsequent recall

Williams Syndrome Caused by the deletion of a dozen genes

from one of the two chromosomes numbered 7

Shows dissociation between language and intelligence, patients are: Fluent in language But cannot tie their shoe laces, draw images,

etc. Developmental process is altered:

Number skills good at infancy, poor at adulthood

Language skills poor at infancy, greatly improved in adulthood

Lateralization of the Brain

Human body is asymmetrical: heart, liver, use of limbs, etc.

Functions of the brain become lateralized

Each hemisphere specialized for particular ways of working

Split-brain patients are good examples of lateralization of language functions

Lateralization of functions(approximate)

Left-hemisphere: Sequential analysis

Analytical Problem solving

Language

Right-hemisphere: Simultaneous analysis

Synthetic Visual-Spatial skills

Cognitive maps Personal space Facial recognition Drawing

Emotional functions Recognizing emotions Expressing emotions

Music

Split-brain

Epileptic activity spread from one hemisphere to the other thru corpus callosum

Since 1930, such epileptic treated by severing the interhemispheric pathways

At first no detectible changes (e.g. IQ) Animal research revealed deficits:

Cat with both corpus callosum and optic chiasm severed

Left-hemisphere could be trained for symbol:reward Right-hemisphere could be trained for inverted

symbol:reward

Left vs. Right Brain Pre and post operation studies showed that:

Selective stimulation of the right and left hemisphere was possible by stimulating different parts of the body (e.g. right/left hand):

Thus can test the capabilities of each hemisphere Left hemisphere could read and verbally

communicate Right hemisphere had small linguistic capacity:

recognize single words Vocabulary and grammar capabilities of right is far

less than left Only the processes taking place in the left

hemisphere could be described verbally