Content includes basic physiology of language an speech. along with description of brain areas involved as well as basic knowledge of different types aphasia.

1. Physiology of Language and Speech
Dr. Abhilasha Mishra
Assistant Professor
Physiology Department

2. • Language is one of the fundamental bases of
human intelligence and a key part of human
culture.
• One of the most important differences
between human beings and lower animals is
the facility with which human beings can
communicate with one another.

3. Location of some of the areas in the categorical
hemisphere that are concerned with language functions.

4. • 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.

5. • It projects via the arcuate fasciculus to Broca’s
area in the frontal lobe immediately in front of
the inferior end of the motor cortex.
• 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.

6. • There are two aspects to communication:
• first, the sensory aspect (language input),
involving the ears and eyes.
• second, the motor aspect (language output),
involving vocalization and its control.

7. Sensory Aspects of Communication
• Destruction of portions of the auditory or
visual association areas of the cortex can
result in inability to understand the spoken
word or the written word.
• These effects are called, respectively, auditory
receptive aphasia and visual receptive
aphasia or, more commonly, word deafness
and word blindness (also called dyslexia).

8. Brain pathways for perceiving a heard word
and then speaking the same word

9. Brain pathway for perceiving a written word
and then speaking the same word.

10. angular gyrus
• A region of the inferior parietal lobe of the brain
that is involved in the processing of auditory and
visual input and in the comprehension of
language.
• Lesion to this part of the brain shows symptoms
of the Gerstmann syndrome: effects include
finger tap agnosia, alexia (inability to read),
acalculia (inability to use arithmetic operations),
agraphia (inability to copy), and left-right
confusion.

11. Arcuate fasciculus
• Broca's area and Wernicke's
area are connected by a bundle of nerve fibers
called the arcuate fasciculus. Damage to the
arcuate fasciculus causes a disorder called
conduction aphasia.
• Conduction aphasia, also called
associative aphasia, is a relatively rare form of
aphasia. An acquired language disorder, it is
characterized by intact auditory comprehension,
fluent (yet paraphasic) speech production, but
poor speech repetition.

12. Motor Aspects of Communication
• The process of speech involves two principal
stages of mentation:
• (1) formation in the mind of thoughts to be
expressed, as well as choice of words to be
used, and then
• (2) motor control of vocalization and the
actual act of vocalization itself.

13. • Sometimes a person is capable of deciding
what he or she wants to say but cannot make
the vocal system emit words instead of noises.
• This effect, called motor aphasia, results from
damage to Broca’s speech area, which lies in
the prefrontal and premotor facial region of
the cerebral cortex.

14. • the skilled motor patterns for control of the
larynx, lips, mouth, respiratory system, and
other accessory muscles of speech are all
initiated from this area.

15. Articulation
• muscular movements of the mouth, tongue,
larynx, vocal cords, and so forth that are
responsible for the intonations, timing, and rapid
changes in intensities of the sequential sounds.
• The facial and laryngeal regions of the motor
cortex activate these muscles, and the
cerebellum, basal ganglia, and sensory cortex all
help to control the sequences and intensities of
muscle contractions, making liberal use of basal
ganglial and cerebellar feedback mechanisms.

18. LANGUAGE DISORDERS
• 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. Many
different classifications of the aphasias have been
published, but a convenient classification divides
them into nonfluent , fluent , and anomic
aphasias .

19. Nonfluent aphasia
• In nonfluent 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.
• Sometimes the words retained are those that
were being spoken at the time of the injury or
vascular accident that caused the aphasia.

20. Fluent aphasia
• In one form of fluent aphasia, the lesion is in
Wernicke’s area.
• In this condition, 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, so other aspects of
the use of language are compromised.

23. conduction aphasia
• patients can speak relatively well and have
good auditory comprehension but cannot put
parts of words together or conjure up words.
• It was thought to be due to lesions of the
arcuate fasciculus connecting Wernicke’s and
Broca’s areas.

24. anomic aphasia
• When a lesion damages the angular gyrus in the
categorical hemisphere without affecting
Wernicke’s or Broca’s areas,
• There is no difficulty with speech or the
understanding of auditory information;
• Instead there is trouble understanding written
language or pictures, because visual information
is not processed and transmitted to Wernicke’s
area.
• The result is a condition called anomic aphasia.

25. Global Aphasia
• Involving both receptive and expressive
functions. In this situation, speech is scant as
well as nonfluent.
• Writing is abnormal in all aphasias in which
speech is abnormal, but the neural circuits
involved are unknown.
• In addition, deaf subjects who develop a
lesion in the categorical hemisphere lose their
ability to communicate in sign language.