1. Physiology of Language

2. AREAS
The primary brain areas concerned with language
are arrayed along and near the sylvian fissure (lateral cerebral sulcus) of the categorical hemisphere.
A region at the posterior end of the superior temporal gyrus called Wernicke’s area is concerned with comprehension of auditory and visual information.
Broca’s area (area 44) in the frontal lobe.

3. Broca’s area processes the information received from Wernicke’s area into a detailed and coordinated pattern for vocalization
and then projects the pattern via a speech articulation area in the to the motor cortex, which initiates the appropriate movements of the lips, tongue, and larynx to produce speech.
The angular gyrus behind Wernicke’s area appears to process information from words that are read in such a way that they can be converted into the auditory forms of the words in Wernicke’s area.

4. Location of language areas

5. 4 Processes in Speech Production
Respiration
Phonation
Resonance
Articulation

6. Respiration: Power Mechanism
Provides the energy for sound
Breathing results in:-
a difference in air pressure is between the thoracic cavity and the atmospheric pressure outside the body

7. organs of respiration
– trachea
– rib cage
– thorax
– abdomen
– diaphragm
– lungs

8. HOW IT WORKS at rest, inhale and exhale with equal time
thoracic cavity expands
lungs expand, creating negative pressure and air now available for speaking
to speak, lungs deflate and rib cage contracts forcing air out

9. Phonation: Vibrating Mechanism
Phonation is the rapid opening and closing of the vocal folds for sound
the vocal folds lie horizontally in the larynx
They are attached anteriorly to the thyroid cartilage and posteriorly to the artynoid cartilages; they are free in the middle.
the opening in the middle of the vocal folds is the GLOTTIS

10. • when airstream enters larynx, subglottic pressure builds up
when pressure is great enough, vocal folds are pushed apart air flows through glottis reduction of pressure pulls vocal folds back together
aerodynamic principle related to pressure changes called Bernouli effect

11. when vf are apart = abducted so opening
is abduction
when vf together = adducted
during phonation, vf’s alternate between
abduction and adduction

13. ARTICULATION
articulation = joining together of speech organs for production of speech.
Articulation is act of creating speech sounds
The various articulators (Teeth, lips, tongue, jaw, etc.) alter the size, shape, and other characteristics of the resonant spaces in the vocal mechanism

14. Aphasias
Aphasias are abnormalities of language functions that are not due to defects of vision or hearing or to motor paralysis.
They are caused by lesions in the categorical hemisphere.
Fluent, nonfluent, and anomic aphasias.

15. In nonfluent aphasia (EXPRESSIVE APHASIA, ANTERIOR APHASIA)
the lesion is in Broca’s area
Speech is slow, and words are hard to come by.
Patients with severe damage to this area are limited to two or three words with which to express the whole range of meaning and emotion.

16. Fluent Aphasia ( RECEPTIVE APHASIA, POSTERIOR APHASIA)
Lesion in the wernicke’s area
Speech itself is normal and sometimes the patients talk excessively.
However, what they makes little sense.
The patient also fails to comprehend the meaning of spoken or written words.

17. conduction aphasia
Lesion in the auditory cortex (areas 40, 41 &42)
patients can speak relatively well and have good auditory comprehension but cannot put parts of words together or conjure up words.
This is called conduction aphasia because it was thought to be due to lesions of the arcuate fasciculus connecting Wernicke’s and Broca’s areas.

18. Anomic aphasia
When there is a lesion damaging the angular gyrus.
There is trouble understanding written language or pictures, because visual information is not processed and transmitted to Wernicke’s area.

19. auditory association areas word deafness
LESION FAETURES
auditory association areas
word deafness
visual association areas
word blindness called dyslexia
Wernicke's Aphasia
Global Aphasia
unable to interpret the thought
Sensory Aphasia
Broca's Area Causes
Motor Aphasia

20. GLOBAL APHASIA
(CENTRAL APHASIA)
This means the combination of the expressive problems of Broca's aphasia and the loss of comprehension of Wernicke's.
The patient can neither speak nor understand language.
It is due to widespread damage to speech areas and is the commonest aphasia after a severe left hemisphere infarct.
Writing and reading are also affected.

21. DYSARTHRIA DISORDERED ARTICULATION Slurred speech. Language is intact
Paralysis, slowing or incoordination of muscles of articulation or local discomfort causes various different patterns of dysarthria.
Examples
the monotone of Parkinson's disease (Slurred),
speech in myasthenia that fatigues and dies away. Many aphasic patients are also somewhat dysarthric.

22. WIDESPREAD DAMAGE TO SPEECH AREAS
APHASIA
EXPRESSIVE
RECEPTIVE
NON FLUENT
BROCA'S AREA
WERNICK’S AREA CONDUCTION APHASIA
FLUENT
ANOMIC
ANGULAR GYRUS
WIDESPREAD DAMAGE TO SPEECH AREAS
GLOBAL

23. Speech aparatus
Air must be pushed through vocal tract to produce sound.
System must control precisely the shape of the vocal tract.
Does so by modulating behaviour of 3 subsystems.

24. Respiratory subsystem
Respiratory subsystem (power system)
Controls the diaphragm and external intercostals to inhale
Internal intercostals: most important respiratory muscles for speech
- propel air out (exhale)
- control speech volume by regulating the amount of pressure

25. Laryngeal mechanism (sound source)
Regulates pitch by changing the stiffness of the vocal chords
Modulates aspiration
Allows for whispering
Creates voicing (e.g., “v” versus “f”)

26. Articulatory subsystem
Responsible for the remaining distinctions of speech
Structures: mouth, jaw, lips, nasal tract, velum (flap connecting nasal tract and oral cavity) and pharynx

27. Articulatory subsystem
Articulatory subsystem (acoustic filter)
Pharynx: shape produces different vowels; human infants, pre-human hominids and apes have short necks, high larynx and small immobile throats, so unable to produce vowels (but also can’t choke).