functions of cerebral cortex in hearing and pathway

1. Function of cerebral cortex
in
hearing

2. General information
• The cerebral cortex is the outer covering of
gray matter over the hemispheres.
• Certain cortical regions have somewhat
simpler functions, termed the primary
cortices.
• These include areas directly receiving sensory
input (vision, hearing, somatic sensation) or
directly involved in production of limb or eye
movements

3. FUNCTION OF THE AUDITORY CORTEX
• Primary auditory cortex (AI)
• Secondary auditory cortex (AII)
• The belt region

4.  Primary auditory cortex:
• composed of neurons involved in decoding the cochleotopic and tonotopic
spatial representation of a stimulus.
• the part of the temporal lobe that processes auditory information in humans.
 Secondary auditory cortex:
• which doesn't have clear tonotopic organization but has an important role in
sound localization and analysis of complex sounds: in particular for specific
animal vocalizations and human language.
• It also has a role in auditory memory.
 The belt region:
• surrounding AI and AII, which helps to integrate hearing with other sensory
systems

5. Functions Primary auditory area
• Primary auditory area is concerned with perception of auditory
impulses, analysis of pitch and determination of intensity and source of
sound.
• Area 41 and 42 are concerned only with the perception of auditory
sensation (sound).
• Wernicke area is responsible for the interpretation of auditory
sensation.
• It carries out this function with the help of secondary auditory area 22.
• Wernicke area is also responsible for understanding the auditory
information about any word and sending the information to Broca
area.

6. MAIN FUNCTION OF PRIMARY AUDITORY CORTEX
• The neurons in the primary auditory cortex are
organized tonotopically, meaning that the
neurons in the auditory cortex react best to
specific frequencies.
• At one end of the auditory cortex, neurons react
best to low frequencies.
• the other end, they react to high frequencies.

7. Secondary Auditory area
• Secondary auditory area occupies the
superior temporal gyrus.
• It is also called or auditory association
area.(includes area 22)
• This area is concerned with interpretation of
auditory sensation along with Wernicke area.
• It is also concerned with storage of memories
of spoken words.

8. Auditory Brain
• Auditory messages are conveyed to the brain via two types of pathway:
1. PRIMARY AUDITORY PATHWAYS
2. NON-PRIMARY PATHWAYS
• primary auditory pathway which exclusively carries messages from the
cochlea.
• non-primary pathway (also called the reticular sensory pathway) which
carries all types of sensory messages.

9. PRIMARY AUDITORY PATHWAYS
COCHLEA
COCHLEAR NUCLEI
SUPERIOR OLIVE
INFERIOR COLLICULUS
THALAMUS
AUDITORY CORTEX

10. NON-PRIMARY PATHWAYS
COCHLEA
COCHLEAR NUCLEI
RETICULAR FORMATION
THALAMUS (NON SPECIFIC)
CORTEX LIMBIC CORTEX HYPOTHALAMUS
WAKE EMOTIONAL MOTIVATION

11. Area for equilibrium
• Area for equilibrium is in the posterior part of superior
temporal gyrus.
• It is concerned with the maintenance of equilibrium of
the body.
• Stimulation of the area causes dizziness, swaying,
falling and feeling of rotation.

12. Damage to the Primary Auditory Cortex
• If the whole primary auditory area is damaged, a
person will not be aware of what he hears.
• Yet, an ability to react reflexively to sounds
remains. There are extensive connections from
both ears to both the left and right primary
auditory cortexes.
• person who has had a lesion on one side of the
auditory cortex only, is able to discriminate sound
frequencies quite well.
• Because each primary auditory cortex is mainly
responsible for localizing sounds on the opposite
side.