Function of cerebral cortex

inhearing

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

FUNCTION OF THE AUDITORY CORTEX

• Primary auditory cortex (AI)• Secondary auditory cortex (AII)• The belt region

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

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.

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.

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.

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.

PRIMARY AUDITORY PATHWAYS COCHLEA

COCHLEAR NUCLEI

SUPERIOR OLIVE

INFERIOR COLLICULUS

THALAMUS

AUDITORY CORTEX

NON-PRIMARY PATHWAYS

COCHLEA

COCHLEAR NUCLEI

RETICULAR FORMATION

THALAMUS (NON SPECIFIC)

CORTEX LIMBIC CORTEX HYPOTHALAMUS

WAKE EMOTIONAL MOTIVATION

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.

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.

Thank you