![]() The auditory dorsal stream in both humans and non-human primates is responsible for sound localization, and is accordingly known as the auditory 'where' pathway. The auditory ventral stream pathway is responsible for sound recognition, and is accordingly known as the auditory 'what' pathway. In accordance with this model, there are two pathways that connect the auditory cortex to the frontal lobe, each pathway accounting for different linguistic roles. However, due to improvements in intra-cortical electrophysiological recordings of monkey and human brains, as well non-invasive techniques such as fMRI, PET, MEG and EEG, a dual auditory pathway has been revealed and a two-streams model has been developed. Throughout the 20th century the dominant model for language processing in the brain was the Geschwind-Lichteim-Wernicke model, which is based primarily on the analysis of brain-damaged patients. Language processing is considered to be a uniquely human ability that is not produced with the same grammatical understanding or systematicity in even human's closest primate relatives. In psycholinguistics, language processing refers to the way humans use words to communicate ideas and feelings, and how such communications are processed and understood. Material was copied from this source, which is available under a Creative Commons Attribution 4.0 International License. Top and Bottom: Blue colors mark regions affiliated with the ADS, and red colors mark regions affiliated with the AVS (dark red and blue regions mark the primary auditory fields). Orange frames mark the region of the auditory cortex, which is displayed in the top sub-figures. Bottom: The brain of the monkey (left) and human (right) is schematically depicted and displayed from the side. Top: The auditory cortex of the monkey (left) and human (right) is schematically depicted on the supratemporal plane and observed from above (with the parieto- frontal operculi removed). ( Learn how and when to remove this template message)ĭual stream connectivity between the auditory cortex and frontal lobe of monkeys and humans. Please help update this article to reflect recent events or newly available information. As seen in Figure 13.3, low frequencies are more lateral in primary auditory cortex.This article needs to be updated. This segregation of high and low frequencies persists throughout the CNS. Low frequency fibers then pass in the central core of the VIIth nerve surrounded by high frequency fibers (see Auditory System: Structure and Function). Click on the cochlea in Figure 13.3 to see the color code of pitch, as if the cochlea were a piano. This starts with high frequencies transduced at the base of the cochlea, and low frequencies transduced at the apex (see Figure 12.7). Afferents from this longitudinal strip on the superior temporal gyrus diverge to a wide variety of other cortical processing areas, including Wernicke’s area in the parietal lobe where speech is processed.Īuditory afferents are tonotopically organized from the ear to the cortex. Primary auditory cortex, or Herschel’s gyrus in insular cortex, is tonotopically organized. The two different patterns of dashed lines combine to form a solid line above the superior olive, meant to indicate the combination of monaural inputs into bilateral and binaural activation. Then, click on the cochlea and text to gain further information.įigure 13.3 shows the same detail processing system as in Figure 13.2, only now with the more realistic situation of input from both ears. Thalamic afferents reach the superior temporal gyrus through the sub-lenticular portion of the internal capsule.īinaural auditory afferents. All afferents then synapse in the medial geniculate body of the thalamus. ![]() Most of these afferents synapse in the inferior colliculus. Some nuclei within the lateral lemniscus further process the sound. The output of the superior olive travels in the lateral lemniscus. Thus, cells in the superior olive receive inputs from both ears and are the first place in the central auditory system where binaural processing (stereo hearing) is possible. Some fibers from the ventral cochlear nucleus cross the midline in the trapezoid body. Fibers from the ventral cochlear nucleus synapse in the ipsilateral and contralateral superior olivary nucleus. These fibers synapse in the ventral cochlear nucleus. This slow acting system involves much more processing and may provide more detailed information about the sound, such as its location. Then, click on the cochlea and text to gain further information.įigure 13.2 shows the more numerous connections that work their way rostrally through a more detailed pathway. Ascending pathway for most auditory afferents.
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