The Superior Temporal Gyrus (STG) is a distinct region within the human brain, serving as a hub for processing various types of complex information from the world around us. This brain structure plays a role in interpreting sensory input, particularly auditory signals. It contributes to how we make sense of our surroundings and interact with others. The STG is involved in understanding both spoken language and social cues.
Anatomical Location and Structure
The superior temporal gyrus is situated within the temporal lobe, a large section of the brain located on the sides of the head, roughly above the ears. It forms the uppermost part of this lobe, extending along its length. This gyrus lies just below the lateral sulcus, also known as the Sylvian fissure, which is a significant groove that separates the temporal lobe from the frontal and parietal lobes. The STG runs parallel to this fissure, creating a clear anatomical landmark. The posterior portion of the STG blends into parts of the parietal lobe, connecting with areas like the angular gyrus and supramarginal gyrus.
Auditory and Language Processing
The superior temporal gyrus contains the primary auditory cortex, which is the brain’s main center for processing raw sound information, receiving and interpreting basic auditory features such as pitch, volume, and rhythm of sounds. Specific sound frequencies are mapped precisely onto this auditory cortex, creating a tonotopic organization. Beyond basic sound processing, the STG is involved in language comprehension. A language center, Wernicke’s area, is located in the posterior part of the STG, typically in the left hemisphere. This region is responsible for understanding spoken words and making sense of sentences, as Wernicke’s area transforms those sounds into meaningful language, allowing us to interpret words and their grammatical structure.
Role in Social Cognition
The superior temporal gyrus also contributes significantly to social cognition, helping individuals interpret the social meaning behind sounds and actions, as it processes vocal prosody, which is the emotional tone, cadence, and inflection of speech. This allows us to understand if someone is happy, sad, angry, or sarcastic, even without explicit words. The STG’s involvement extends to “theory of mind,” which is the ability to recognize and attribute mental states to others. This function is associated with the right rostral superior temporal gyrus, and by integrating auditory and visual cues, the STG helps us infer what others might be thinking or feeling, which is fundamental for navigating complex social interactions.
Consequences of Damage or Dysfunction
Damage to the superior temporal gyrus can lead to various impairments, directly affecting the functions it typically performs; for instance, lesions in Wernicke’s area, located within the left posterior STG, often result in receptive aphasia. Individuals with this condition experience significant difficulty understanding spoken language. Abnormalities in the STG are also associated with auditory hallucinations, a symptom frequently observed in conditions like schizophrenia, which involve perceiving sounds, such as voices, that are not actually present. Furthermore, dysfunction in the STG can contribute to difficulties in social perception, making it challenging to interpret non-verbal social cues and understand others’ mental states.