The auditory cortex is involved in tasks such as identifying and segregating " auditory objects" and identifying the location of a sound in space. There are multiple auditory areas (much like the multiple areas in the visual cortex), which can be distinguished anatomically and on the basis that they contain a complete "frequency map." The purpose of this frequency map (known as a tonotopic map) likely reflects the fact that the cochlea is arranged according to sound frequency. Neurons at one end of the auditory cortex respond best to low frequencies neurons at the other respond best to high frequencies. Neurons in the auditory cortex are organized according to the frequency of sound to which they respond best. Damage to the auditory cortex in humans leads to a loss of any awareness of sound, but an ability to react reflexively to sounds remains as there is a great deal of subcortical processing in the auditory brainstem and midbrain. Evidence for this comes from lesion studies in human patients who have sustained damage to cortical areas through tumors or strokes, or from animal experiments in which cortical areas were deactivated by surgical lesions or other methods. Function Īs with other primary sensory cortical areas, auditory sensations reach perception only if received and processed by a cortical area. Sexual dimorphism within the auditory cortex can be seen in humans between males in females through the planum temporale, encompassing Wernicke's region, for the planum temporale within males has been observed to have a larger planum temporale volume on average, reflecting previous studies discussing interactions between sex hormones and asymmetrical brain development. Importantly, the change is persistent, in that it lasts throughout the animal's life, and specific, in that the same exposure outside of that period causes no lasting change in the tonotopy of A1. In the rat, exposure to a single frequency during postnatal day (P) 11 to 13 can cause a 2-fold expansion in the representation of that frequency in A1. This has been best studied using animal models, especially cats and rats. Like many areas in the neocortex, the functional properties of the adult primary auditory cortex (A1) are highly dependent on the sounds encountered early in life. In humans, the structure and function of the auditory cortex has been studied using functional magnetic resonance imaging (fMRI), electroencephalography (EEG), and electrocorticography. Within the core (A1), its structure preserves tonotopy, the orderly representation of frequency, due to its ability to map low to high frequencies corresponding to the apex and base, respectively, of the cochlea.ĭata about the auditory cortex has been obtained through studies in rodents, cats, macaques, and other animals. īesides receiving input from the ears via lower parts of the auditory system, it also transmits signals back to these areas and is interconnected with other parts of the cerebral cortex. The belt is the area immediately surrounding the core the parabelt is adjacent to the lateral side of the belt. The modern divisions of the auditory cortex are the core (which includes primary auditory cortex, A1), the belt (secondary auditory cortex, A2), and the parabelt (tertiary auditory cortex, A3). The auditory cortex was previously subdivided into primary (A1) and secondary (A2) projection areas and further association areas. For example, unilateral destruction, in a region of the auditory pathway above the cochlear nucleus, results in slight hearing loss, whereas bilateral destruction results in cortical deafness. The auditory cortex's function may help explain why particular brain damage leads to particular outcomes. The cortex then filters and passes on the information to the dual stream of speech processing. The auditory cortex takes part in the spectrotemporal, meaning involving time and frequency, analysis of the inputs passed on from the ear. It is located bilaterally, roughly at the upper sides of the temporal lobes – in humans, curving down and onto the medial surface, on the superior temporal plane, within the lateral sulcus and comprising parts of the transverse temporal gyri, and the superior temporal gyrus, including the planum polare and planum temporale (roughly Brodmann areas 41 and 42, and partially 22). It is a part of the auditory system, performing basic and higher functions in hearing, such as possible relations to language switching. The auditory cortex is the part of the temporal lobe that processes auditory information in humans and many other vertebrates. BA22(yellow) is Brodmann area 22, HF(blue) is hippocampal formation and pSTG is posterior part of superior temporal gyrus. BA41(red) and BA42(green) are auditory cortex.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |