Auditory cortex

The auditory or auditory cortex / cortex (from Latin audire = dt " hear " or Latin auditio = dt " hearing " and the Latin cortex = dt " bark " ) - also known as the auditory cortex or the auditory cortex - is the area of the cerebral cortex, which serves the processing and the awareness of acoustic stimuli. He is thus the end point of the auditory pathway.

Anatomical location

In humans, the auditory cortex is located on the top turn of the temporal lobe, the superior temporal gyrus. A significant part lies in the Sylvian fissure ( fissure lateralis) and the frontal and parietal lobes covered; these are the temporal gyri transverse processes, also known as Heschl cross turns are known ( by Richard Heschl ). The comprehension of language associated with Wernicke's area in the supramarginal gyrus is sometimes attributed to the auditory cortex. After Korbinian Brodmann brain atlas of the auditory cortex corresponding to Brodmann's areas 41, 42 and 22, and in part the area is 52 micro Anatomically it is a six-layered isocortex.

Structure and function

The primary (A1, BA 41), the secondary (A2, BA 42) and the tertiary auditory area surrounding each other concentrically. Similarly all primary receptive fields, the primary listening area is a spatial organization: in this case, the frequencies of which have a continuous profile, the so-called tonotopy. So you can draw you a map of the represented frequencies on the brain surface. Low frequencies are fed anterolateral ( front and to the side ), high posteriomedial (to the rear and towards the center ). The secondary and tertiary fields are associative, meaning that they are mainly used to compare, classify and evaluate current listening impressions with the familiar. This happens mostly unconsciously. Awareness, however, penetrate auditory stimuli that are unknown or not einordbar or potentially threatening to indicate ( " cues "), and everything on which you focus. The most important functional aspect of the auditory cortex in humans is language comprehension.

The localization of sound sources in the environment, via the computation of the interaural time difference ( ITD), which is the time it takes for the sound longer to reach the more distant from the source of stimulation ear. If the sound source directly behind or in front of the viewer, the difference is 0 it Is located at an angle of 90 ° to the side of him, they reach a maximum of 0.6 milliseconds.