The transverse temporal gyrus, also called Heschl's gyrus () or Heschl's convolutions, is a

gyrus In neuroanatomy, a gyrus (: gyri) is a ridge on the cerebral cortex. It is generally surrounded by one or more sulci (depressions or furrows; : sulcus). Gyri and sulci create the folded appearance of the brain in humans and other mammals. ...

found in the area of each

primary auditory cortex The auditory cortex is the part of the temporal lobe that processes auditory information in humans and many other vertebrates. It is a part of the auditory system, performing basic and higher functions in hearing, such as possible relations to ...

buried within the lateral sulcus of the

human brain The human brain is the central organ (anatomy), organ of the nervous system, and with the spinal cord, comprises the central nervous system. It consists of the cerebrum, the brainstem and the cerebellum. The brain controls most of the activi ...

, occupying Brodmann areas 41 and 42. Transverse temporal gyri are superior to and separated from the planum temporale (cortex involved in language production) by Heschl's sulcus. Transverse temporal gyri are found in varying numbers in both the right and left hemispheres of the brain and one study found that this number is not related to the hemisphere or dominance of hemisphere studied in subjects. Transverse temporal gyri can be viewed in the sagittal plane as either an omega shape (if one gyrus is present) or a heart shape (if two gyri and a sulcus are present). Transverse temporal gyri are the first cortical structures to process incoming auditory information. Anatomically, the transverse temporal gyri are distinct in that they run mediolaterally (toward the center of the brain), rather than front to back as all other

temporal lobe The temporal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The temporal lobe is located beneath the lateral fissure on both cerebral hemispheres of the mammalian brain. The temporal lobe is involved in pr ...

gyri run. The ''Heschl's gyri'' are named after Richard L. Heschl.

Processing tone

The transverse temporal gyri are active during auditory processing under

fMRI Functional magnetic resonance imaging or functional MRI (fMRI) measures brain activity by detecting changes associated with blood flow. This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area o ...

for tone and semantic tasks. Transverse temporal gyri were found in one study to have significantly faster processing rates (33 Hz) in the left hemisphere compared to those in the right hemisphere (3 Hz). Additionally this difference in processing rate was found to be related to the volume of rate-related cortex in the gyri; right transverse temporal gyri were found to be more active during temporal processing, and these gyri were found to have more “rate-related cortex”. White and grey matter volumes of transverse temporal gyri were not found to relate to this processing speed, although larger white matter volumes in subjects are associated with increased sensitivity to “rapid auditory input”. The role of transverse temporal gyri in auditory processing of tone is demonstrated by a study by Wong, Warrier et al. (2008). This study revealed the following: subjects who could successfully form an association between Mandarin Chinese “pitch patterns” and word meaning were found to have transverse temporal gyri with larger volume than subjects who had “difficulty learning these associations.” Successful completion of the previous task also was found to be associated with a “greater concentration of white matter” in the left transverse temporal gyri of the subject. In general, larger transverse temporal gyri “could be associated with more efficient processing of speech-related cues which could facilitate learning and perceiving new speech sounds.”

Inner voice

Research on the inner voice perceived by humans led to the identification of these gyri as the area of the brain activated during such dialogue with oneself. Specifically, Heschl's gyrus responded to spontaneous inner speech, while it was hypoactive during task-elicited inner speech (repeating words prompted by an experimenter).

Mismatch negativity

One of the famous

event-related potential An event-related potential (ERP) is the measured brain response that is the direct result of a specific sense, sensory, cognition, cognitive, or motor system, motor event. More formally, it is any stereotyped electrophysiology, electrophysiologi ...

(ERP) components is

mismatch negativity The mismatch negativity (MMN) or mismatch field (MMF) is a component of the event-related potential (ERP) to an odd stimulus in a sequence of stimuli. It arises from electrical activity in the brain and is studied within the field of cognitive neu ...

. This component is considered to represent a prediction error process in the brain. This ERP has probably two generators, one in the right prefrontal lobe, and the other in the primary auditory regions - the transverse temporal gyrus and the

superior temporal gyrus The superior temporal gyrus (STG) is one of three (sometimes two) gyri in the temporal lobe of the human brain, which is located laterally to the head, situated somewhat above the external ear. The superior temporal gyrus is bounded by: * the l ...

Additional images

File:Transverse temporal gyrus.gif, 3D view of the transverse temporal gyrus in an average human brain File:Transverse temporal gyrus coronal sections.gif, Transverse temporal gyrus highlighted in green on coronal T1 MRI images File:Transverse temporal gyrus sagittal sections.gif, Transverse temporal gyrus highlighted in green on sagittal T1 MRI images File:Transverse temporal gyrus transversal sections.gif, Transverse temporal gyrus highlighted in green on transversal T1 MRI images

References

External links

The peri-sylvian aphasias

Heschl's Gyrus: Anatomic description and methods of identification in MRI

Relating structure to function: Heschl's Gyrus and acoustic processing
{{Authority control Gyri Temporal lobe