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SPEECHLecture – 11

Dr. Zahoor Ali Shaikh

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SPEECH What is Speech ? Speech is complex form of

communication in which spoken words convey ideas.

When we speak, first we understand.

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SPEECH For understanding and speaking, we have

two speech centers: 1. Broca’s area – motor speech area 2. Wernicke’s area – sensory speech areaBoth are connected by ARCUATE FASCICULUS.

How we speak? Because of speech centers and articulation

of muscles of speech.

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SPEECH

1. Broca’s area It is located in left frontal lobe in close

association with motor areas of the cortex.

It is for speaking– Word formation Brocas area simultaneously excites

Motor area which controls the muscles necessary for articulation.

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SPEECH

2. Wernicke’s area It is located in the left cortex at

Superior gyrus of Temporal lobe at the juncture of parietal, temporal and occipital lobes.

It is concerned with language comprehension (understanding).

It plays important role in understanding of both spoken and written messages.

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SPEECH

2. Wernicke’s area It is also responsible for formulating

coherent pattern of speech, that are transferred via bundle of fibers ARCUATE FASCICULUS to brocas’s area.

Wernicke’s area receives input from visual cortex in the occipital lob and also auditory cortex in temporal lobe.

It also gets information from somatosensory cortex.

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PATHWAY FOR HEARING & SPEAKING

Steps are: 1. Reception in the primary auditory cortex area of

sound signals.2. Interpretation of words in Wernicke's area.3. Determination of thoughts in words to be spoken

in Wernicke’s area.4. Transmission of signals from Wernicke’s area to

Broca’s area by Arcuate fasciculus.5. Word formation in Broca’s area.6. Transmission of signals to motor cortex to

control the speech muscles.

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PATHWAY FOR SEEING WRITTEN WORD & THEN SPEAKING

Steps are:1. Reading the words – reception in

primary visual area.2. Information passes through angular

gyrus region and reaches Wernicke's area.

Step 3 to Step 6 are same for speaking as in response to hearing words.

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SPEECH AREA LOCATION Speech area are located in one sphere

(on one side), usually left hemisphere. Left hemisphere is also dominant for

fine movements). Left hemisphere is therefore

DOMINANT SPHERE.

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SPEECH AREA LOCATION Right handed people have speech

center in left hemisphere i.e Dominant hemisphere

90% of left handed people have left cerebral hemisphere as dominant also.

10% of left handed people have right hemisphere as dominant for speech.

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SPEECH AREA LOCATION Most people are right handed, as left

side of the brain controls the right side of the body.

Left cerebral hemisphere – excels in logical, analytic, and verbal task e.g. math, language forms, philosophy.

Left cerebral dominance is associated with thinkers.

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SPEECH AREA LOCATION

Right cerebral hemisphere It excels in non-language skills e.g.

artistic and musical talents. Therefore, right hemisphere dominance

is associated with creators.

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LANGUAGE DISORDERS Damage to the specific regions of brain

can result in selective disturbance of speech.

We will discuss Damage to Brocas’s area (motor aphasia) Damage to Wernicke’s area (sensory

aphasia) Damage to ARCUATE FACICULUS Speech Disorders of Articulation

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SPEECH DISORDER Speech disorders – two main groups 1. Dysphasia – disorder of language

area in the dominant hemisphere. 2. Disorders of articulation

(dysarthria) and disorders of phonation (dysphonia).

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LANGUAGE DISORDERS

Damage to Brocas’s area (motor aphasia) It results in failure of word formation,

but patient can understand the spoken and written words (as Wernicke’s area is functioning).

These people know what they want to say, but can not express themselves.

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LANGUAGE DISORDERS

Damage to Brocas’s area They can not establish the proper

motor command to articulate the desired word, even though they can move their lips and tongue.

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LANGUAGE DISORDERS

Damage to Wernicke’s area (sensory aphasia)

These patients can not understand the words they hear or see.

They can speak fluently, their articulation is perfect, but their speaking makes no sense.

WHY ? Because they can not attach meaning to

words to convey their thoughts.

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LANGUAGE DISORDERS

Damage to ARCUATE FACICULUS Striking defect is inability to repeat

phrases or words spoken by the examiner. It is called CONDUCTION APHASIA.

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LANGUAGE DISORDERS Global Aphasia - Damage occurs to both broca’s area

and Wernicke's area.- Patient can not understand or speak.

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LANGUAGE DISORDERS

Speech Disorders of Articulation (Dysarthria)

They occur due to - weakness of articulating muscles - in-coordination of articulating

muscles

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DYSARTHRIA Dysarthria can be i) Mechanical factors - ill fitting dancherii) Weakness of orolingual muscles

concerned with speech - Problem may be in muscle, nerve

supply or cerebellum

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DYSARTHRIA

1. Cerebellar disease cause speech, with increased word length.

- Ask patient to say constitution, he will say cons-ti-tu-tion, it is called scanning speech.

2. Parkinsonism (basal ganglia) - Speech is monotonous, slurring dysarthria

Dysarthric speech is difficult to understand.

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DYSPHONIA In Dysphonia, sound is not pronounced

properly. Dysphonia is usually due to laryngeal

problem.

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Summary of Speech Disorders

1. Damage of Broca’s area – motor, non-fluent aphasia.2. Damage to Wernicke’s area – sensory aphasia, fluent

speech but having no sense.3. Global aphasia – both motor and sensory speech are

lost (damage to broca’s and Wernicke's area).4. Damage to Arcuate fiber – conduction aphasia.5. Dysarthria – articulation affected. Cerebellar disease – scanning speech. Parkinsonism – slurred, monotonous speech. Myasthenia gravis – speech fatigue, speech dies

away.

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STAMMERING SPEECH It is a speech disorder, where person

prolongs the word usually at vowels (a,e,i,o,u).

e.g. To-to-to-to-morrow Mmmmmmm ilk Commonly occurs by age of 2½ to 3 ½ years. Factors which precipitate – stress. Majority of children grow out of it but in some it

remains and requires speech therapy.

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DYSLEXIA Dyslexia is difficulty in learning due to

auditory reception (word deafness) or visual reception (word blindness).

What is the cause? Because it is developmental problem

where connection between visual and speech area of cortex is faulty – “faulty wiring”.

In dyslexia, there is no intellectual problem.

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IMPORTANT INFORMATION

Speech center is found in one hemisphere i.e. left side.

But if a child below 2 years has damage to left cerebral hemisphere then language function are transferred to right hemisphere with no delay in language development.

This is due to plasticity or remodeling of brain in response to varying demands. It is due to formation of new neural pathways or connections (not new neurons).

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IMPORTANT INFORMATION

Up to the age of 10 years, if damage occurs to left hemisphere, language activity can be re-established in the right hemisphere after a temporary period of loss.

After 10 years, there may be permanent loss of speech as regions of brain involved in spoken and understanding speech are permanently assigned before 13 to 15 years.

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IMPORTANT INFORMATION

Infants can distinguish and articulate the entire range of speech, but each language uses only portion of these sounds.

As child matures, they often loose the ability to distinguish or express speech sounds that are not important in their native language.

Therefore, child learns any language e.g. Arabic, English, Japanese..etc, which is taught to them.

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Thank you