Auditosensory cortex
[2] The auditosensory cortex takes part in the reception and processing of auditory nerve impulses, which passes sound information from the thalamus to the brain.
The distinct structure occupied Brodmann area 42 and was later named the transverse temporal gyri of Heschl.
[6] The primary auditory cortex lies medially in the superior temporal gyrus of the human brain.
[2] The auditosensory cortex is a differentiated anatomical area within the posterior-medial field of the transverse temporal gyrus of Heschl in the lateral sulcus.
[8] The cortex of transverse temporal gyrus of Heschl forms a homogeneous structural region with Brodmann area 22.
The language competence directly correlates with the ability of auditosensory cortex in terms of strength and frequency of neuronal activity.
The perception of auditory signals came as a nervous impulse from the inner ear to the cochlear nuclei of the brainstem,[11] which is the first relay station.
The impulse reaches the auditory cortical projections on the superior temporal gyrus, which is the auditosensory cortex.
The subcortical structures, such as the thalamus, are necessary for controlling emotional and cognitive integration, and the cerebellum for coordinating movements.
[13] Its lateral aspect maps the sound impulse in a tonotopic organisation that produces a mirror image of spatial gradients of frequency sensitivity.
The early processing of speech recognition requires the ability of the transverse temporal gyrus to discriminate frequency.
[13] The information processing pathway in the transverse temporal gyrus is necessary for recognizing and comprehending speech, and has been referred to as the two-streams hypothesis.
Neural activities in other brain areas are closely bound up with auditosensory processing in the transverse temporal gyrus.
Animal studies have shown that extirpation of the auditosensory cortex leads to the loss of responsiveness to previously learnt tones.
Therefore, any surgical procedure should take these anatomical variations into account to minimise the damage to our auditory and language functions.
There are fewer nerve fibres and less myelination in patients' primary auditory cortex, illustrated by the higher grey matter-to-white matter ratios in the Heschl gyrus.
However, this sensorineural hearing loss shows no damage to the auditory pathway from the cochlea to the upper brainstem.
[21] The Heschl gyrus undergoes deterioration, as shown by the low activity of the primary auditory cortex after stimulation.
The patients may become reluctant to communicate or even unable to understand verbal or written language, eventually causing primary progressive aphasia.
In the case of an average individual, speaking-induced suppression is generated due to speaking to reduce the activity in the primary auditory cortex.
However, this is not demonstrated in individuals with schizophrenia, in contrast, there is an increased activity in the auditory cortex instead of sound suppression.
