MBBS PHYSIOLOGY LECTURE

1. Dr Raghuveer Choudhary Asstt. Prof.
Department of Physiology
Dr S.N.Medical College
Jodhpur
Physiology of Language and
speech

3. Language is one of the fundamental
bases of human intelligence and a
key part of human culture.
To understand the spoken & printed
words & to express ideas in speech
& writing is called Language.
Physiology of Language

5. Language: refers to vocabulary & syntax
independent of mode of production or
comprehension
Speech: actual production or writting
Vocalization: production of sound without
linguistic content

6. Types of speech
1. Spoken speech:
understanding spoken words & expressing
ideas in speech
2. Written speech:
understanding written words and expressing
ideas in writing

7. Categorical Hemisphere Representational Hemisphere
 Functions alloted to left hemishere in
right handed person
 Right hand control
 Spoken language
 Written language
 Mathematical skills
 Scientific skills
 Reasoning
 Functions alloted to right
hemishere in right handed person
 Left hand control
 Music awareness
 Art awareness
 3 dimensional
awareness
 Imagination
 insight

10. Cerebral Dominance
 Categorical hemisphere- analytic processes
 Representational hemisphere- visuospatial
relations
 90% left hemisphere is categorical
 70% of left handed have left hemisphere
dominance

11. Language areas of brain
Broca’s area: anterior speech area
Location- 3rd frontal gyrus
Detailed and co-ordinated pattern of vocalization

12. Important Areas for Language

13. 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.
It projects via the arcuate fasciculus to Broca’s
area (area 44) in the frontal lobe.
Anatomy of language areas

14. Important Areas for Language

15. Exners Area
Dejerine area
Wernicks area

17. 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 insula 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.

18. Location of language areas

19. Brain Areas Concerned with Language
 Wernick’s Area(22)
 Broca’a Area(44,45)
 Motor writing area(Exners Area)(6)
 Motor Cortex
 Angular Gyrus(Dejerine Area)(39)

20. Broca’s and Wernicke’s:
Summary
 Lesion (injury) studies:
 Show that a brain area is necessary for a given task
 Without Broca’s area, you can’t produce speech
 Without Wernicke’s area, you can’t understand speech
If you lose these areas, you
lose language
When you use language, you
use those areas

21. Types of speech
1. Spoken speech:
understanding spoken words & expressing
ideas in speech
2. Written speech:
understanding written words and expressing
ideas in writing

22. Mechanism of speech
Primary auditory cortex/primary visual area
Auditory/visual association areas
Dejerine’s area
Wernicke’s area

23. Arcuate fasciculus
Broca’s area
Exner’s area
Motor area
Vocalization/Writing

24. The probable
sequence
of events
when a subject
names
a visual object
(horizontal
section of hum-
an brain)

27. It is interesting that in individuals who
learn a second language in adulthood,
fMRI reveals that the portion of Broca’s
area concerned with it is adjacent to but
separate from the area concerned with the
native language.
 However, in children who learn two
languages early in life, there is only a single
area involved with both.

30. Speech/Language Disorders
Aphasias: Abnormalities of language
functions not due to defects of vision,
hearing or motor system
Classification:
1. Fluent aphasia
2. Non-fluent aphasia
3. Anomic aphasia

35. 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.
 The most common cause is embolism or
thrombosis of a cerebral blood vessel.
 Fluent(sensory), nonfluent (motor), and anomic
aphasias.

36. In nonfluent aphasia
(EXPRESSIVEAPHASIA,MOTOR 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.
The words retained are those which were being
spoken at the time of the injury or vascular
accident that caused the aphasia.

37. Paul Broca and “Tan”
 In 1861, Broca examined
a patient nicknamed
“Tan,” after the syllable
he said most often.
 The area of damage in
Tan’s case is now known
as “Broca’s area.”

38. Broca’s area: crucial for speech production
 Tan’s brain: lesion (injury) in left frontal cortex
Paul Broca (1861): patient "Tan”
• Severe deficit in speech production: could only say “tan”
• Good language comprehension

39. Nonfluent aphasia (Motor aphasia):
Slow & effortful
No grammar
Telegraphic speech
Incorrect writing/agraphia
Good comprehension

40. Nonfluent aphasia (Motor aphasia):
 Broca’s area contains memories of the sequences
of muscular movements that are needed to
articulate words
 Often become frustrated by their inability to speak
correctly; however, comprehension is not perfect
 Difficulty in comprehending meaning from word
order (“The horse kicks the cow” vs. “The cow
kicks the horse”)

41. Nonfluent aphasia (Motor aphasia):
 3 major speech deficits with Broca’s aphasia:
 Agrammatism – difficulty in comprehending
or properly employing grammatical devices,
such as verb endings and word order
 Anomia – difficulty in finding (remembering)
the appropriate word to describe an object,
action, or attribute
 Difficulty with articulation – mispronounce
words, often realizing it afterwards, and trying
to correct it

42. Fluent Aphasia ( RECEPTIVE APHASIA, SENSORY
APHASIA)
Lesion in the wernicke’s area
Speech itself is normal and sometimes the
patients talk excessively.
 However, what they say is full of jargon and
neologisms that make little sense.
The patient also fails to comprehend the
meaning of spoken or written words.

43. SENSORY APHASIA
 Difficulty in understanding the meaning of
speech
 Motor speech is intact,so patient talk fluently
 Anomia-inability to find an appropriate word to
express a thought
 Neologism-creating new words or meaning for
established words
 Impairment in reading and writing

44. Speech comprehension
Must not just recognize words, we must
understand their meaning
Wernicke’s area contains neural circuits
that accomplish this task

45. Wernicke’s aphasia – a form of aphasia characterized by poor
speech comprehension and fluent but meaningless speech
Comprehension tested by directing movement toward objects
asked about by experimenter is also poor (e.g. “Point to the ink
bottle” – patient cannot point to ink bottle)
However, patients seem unaware of their deficit, unlike with
Broca’s aphasia
They do not recognize that their speech is faulty, nor that
they do not comprehend other speech
Wernicke suggested that this area is a location where memories
of the sequences of sounds that constitute words are stored

46. Broca’s and Wernicke’s Aphasia
 Damage to Wernicke’s
area.
 Speech is fluent, but
meaningless.
 Comprehension is very
poor.
 Sound substitutions are
common.
 Repetition is poor.
 Damage to Broca’s area.
 Speech is not fluent.
 Comprehension is
affected, but good.
 Repetition is very poor.

47. 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.

48. Conduction Aphasia
 Damage to arcuate
fasciculus.
 Speech production is
good.
 Comprehension is
good.
 Sound substitutions are
common.
 Repetition is poor.

49. Anomic aphasia:
Injury to angular gyrus
Difficulty in understanding written language and
pictures
Global aphasia:
Injury to both broca’s & wernicke’s area

50. 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.

51. Type of Aphasia and
Site of Lesion
Characteristic Naming
Errors
Nonfluent (Broca’s area)
Fluent (Wernicke’s area)
Fluent (areas 40, 41 and 42;
conduction aphasia)
Anomic (angular gyrus)
“Tssair”
“Stool” or “choss”
(neologism)invented word
“Flair . . . no, swair . . .
tair”
“I know what it is . . .
I have a lot of them”
Aphasias. Characteristic responses of
patients with lesions in various areas when
shown a picture of a chair

52. AREA 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

53. 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.

54. Global Aphasia
 Damage to Broca’s area, Wernicke’s area
and the arcuate fasciculus.
 Abilities to speak, comprehend and repeat
are impaired.

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

56. Language
 Broca’s area:
 Involves articulation of speech.
 In damage, comprehension of speech in unimpaired.
 Wernicke’s area:
 Involves language comprehension.
 In damage, language comprehension is destroyed, but speech is
rapid without any meaning.
 Angular gyrus:
 Center of integration of auditory, visual, and somatesthetic
information.
 Damage produces aphasias.
 Arcuate fasciculus:
 To speak intelligibly, words originating in Wernicke’s area must be
sent to Broca’s area.
 Broca’s area sends fibers to the motor cortex which directly controls the
musculature of speech.

57. Dyslexia:
Impaired ability to read
Phonemic deficit
Artists, musicians, mathematicians
Dysarthria:
Imperfect vocalization
Defect in motor areas & their connections

58. Dyslexia
which is a broad term applied to impaired ability
to read, due to an inherited abnormality.
Causes of Dyslexia:
1. Reduced ability to recall speech sounds, so
there is trouble translating them mentally into
sound units (phonemes).
2. There is a defect in the magnocellular portion
of the visual system that slows processing
and also leads to phonemic deficit.
3. There is decreased blood flow in angular
gyrus in categorical hemisphere in both
cases.

59. Brain Activation During Reading
 Reader with dyslexia shows less activation of Wernicke’s area and the angular
gyrus and more activation of Broca’s area.

60. DYSARTHRIA
Slurred speech.
Language is intact
Paralysis, slowing or incoordination of muscles of
articulation or local discomfort causes various different
patterns of dysarthria.
DISORDERED ARTICULATION
Examples
•'gravelly' speech of upper motor neurone lesions of
lower cranial nerves,
• jerky, ataxic speech of cerebellar lesions (Scanning
Speech),
•the monotone of Parkinson's disease (Slurred),
•speech in myasthenia that fatigues and dies away. Many
aphasic patients are also somewhat dysarthric.

61. nasal tract
(hard) palate
oral tract
velum (soft palate)
velic port
tongue
tongue tip
pharynx
glottis
(vocal folds and
space between vocal cords)
vocal folds (larynx)
= vocal cords
alveolar ridge
lips
teeth
The Speech Production Apparatus (from Olive, p. 23)
Acoustic Phonetics: Anatomy

62. Acoustic Phonetics: Anatomy
Types of phonation (from Daniloff, p. 194)
quiet
breathing
forced
inhalation
normal
phonation whisper

63. Recognition of face
 Right inferior temporal lobe
 Prosopagnosia
 Autonomic changes

64. An important part of the visual input goes to the
inferior temporal lobe, where representations of
objects, particularly faces, are stored.
In humans, storage and recognition of faces is
more strongly represented in the right inferior
temporal lobe in right-handed individuals,
though the left lobe is also active.
 Lesions in this area cause prosopagnosia, the
inability to recognize faces.
 They can recognize people by their voices, and
many of them show autonomic responses when
they see familiar as opposed to unfamiliar faces.
However, they cannot identify the familiar faces
they see.

66. THANK YOU