User:Carlyleannah/sandbox

[Introduction Redo] <-- will not be actual heading

The superior temporal sulcus (STS) is the sulcus separating the superior temporal gyrus from the middle temporal gyrus in the temporal lobe of the brain. A sulcus (plural sulci) is a deep groove that curves into the largest part of the brain, the cerebrum, and a gyrus (plural gyri) is the a ridge that curves outward of the cerebrum. The STS is located under the lateral fissure, which is the fissure that separates the temporal lobe, parietal lobe, and frontal lobe. The superior temporal sulcus has an asymmetric structure between the left and right hemisphere, with the STS being longer in the left hemisphere, but deeper in the right hemisphere. This asymmetrical structural organization between hemispheres has only been found to occur in the STS of the human brain. The STS has been shown to produce strong responses when subjects perceive stimuli in research areas that include theory of mind, biological motion, faces, voices, and language.

Multisensory processing

• Studies reveal multisensory processing capabilities. Research has documented activation in the STS as a result of five specific social inputs, and thus the STS is assumed to be implicated in social perception. It showed increased activation related to: voices versus environmental sounds, stories versus nonsense speech, moving faces versus moving objects, biological motion, and theory of mind (false belief stories versus false physical stories). It is involved in the perception of where others are gazing (joint attention) and is thus important in determining where others' emotions are being directed.

Phonological processing

• The majority of studies find it is the middle to the posterior portion of the STS that is involved in phonological processing, with bilateral activation indicated though including a mild left hemisphere bias due to greater observed activation. However, the role of the anterior STS in the ventral pathway of speech comprehension and production has not been ruled out. Evidence for the involvement of the middle portion of the STS in phonological processing comes from repetition-suppression studies, which use fMRI to pinpoint areas of the brain responsible for specialized stimulus involvement by habituating the brain to the stimulus and recording differences in stimulation response. The resulting pattern showed expected results in the middle portion of the STS.

Sign language processing

Research shows that the Broca's area of the brain is activated during sign language production and processing. Although Broca's area is found in the frontal lobe, it receives connection from the superior temporal gyrus, including the STS. Native signers are people who learned and have been using sign language, such as American Sign Language (ASL), from birth, and/or use it as their first language. They often learn sign language from their parents and continue its use throughout their lifetime. Sign language activates language regions of the brain, including the STS. There have been studies that show activation of the STS while deaf and hearing native signers perceive sign language, suggesting the STS is tied to the linguistic processing aspect of sign language. Studies also show that there is greater activation of the middle STS in both deaf and hearing signers who acquired ASL earlier than those who acquired it later.

fMRI