Temporal lobe

The temporal lobe is a major part of the cerebral cortex in mammals. It is one of four large lobes that make up the brain. You can find this lobe on both cerebral hemispheres. It is located just beneath a deep groove called the lateral fissure. The name comes from the temples on the sides of the head. This region is vital because it processes sensory input. It turns raw data into meaningful information for the brain.

This processing helps with visual memory, language comprehension, and emotion association.

Memory is one of the most important functions of this lobe. The temporal lobe contains structures required for declarative memory. This is also known as explicit memory. It is the type of memory we use consciously. Declarative memory is divided into two main types. Semantic memory involves remembering facts. Episodic memory involves remembering specific events. The medial temporal lobe is critical for these long-term memories. This area includes the hippocampal formation and the perirhinal cortex. It also includes the parahippocampal and entorhinal neocortical regions.

The hippocampus is a key part of this memory system. It is essential for the formation of new memories. Scientists believe the surrounding medial temporal cortex is critical for storing them. Research on monkeys has shown how these parts work together. Small lesions in the hippocampus cause limited impairment. However, large lesions that include the medial temporal cortex cause severe impairment. Damage to the medial temporal lobes can lead to anterograde amnesia. This is a condition where a person cannot form new memories. This impairment can be temporary or permanent.

Sensory processing also happens within the temporal lobe. For hearing, the lobe contains the primary auditory cortex. This area receives signals from the ears. The superior temporal gyrus is a specific part of this process. It is where auditory signals from the cochlea first reach the cortex. After that, secondary areas process the sounds. They turn them into meaningful units like words or speech. High-level auditory processing happens in the superior, posterior, and lateral parts of the lobe.

Vision is processed differently in the temporal lobe. It does not just see shapes; it interprets their meaning. This allows for object recognition. The ventral part of the temporal cortex handles complex visual stimuli. One specific area is the fusiform gyrus, which helps recognize faces. Another area is the parahippocampal gyrus, which helps recognize scenes. The anterior parts of this visual stream help with object perception.

Language is another complex task for the temporal lobe. In humans, it is critical for accessing the meaning of words. This includes spoken words, printed words, and visual objects. Wernicke's area is a key region for language comprehension. It spans the space between the temporal and parietal lobes. In most people, this is located in the left hemisphere. This area works with Broca's area in the frontal lobe. FMRI imaging shows that these areas activate during language use. This includes spoken language and signed language. It even works for tactile versions of sign language used by children.

Damage to the temporal lobe can cause many different medical issues. A lesion on one side can cause complex hallucinations. These might involve smell, sound, vision, or memory. If the damage is in the dominant hemisphere, it can cause receptive aphasia. This is a type of language disorder. It can also cause dyslexia or anomia, which is difficulty naming things. Damage to the non-dominant hemisphere can impair musical skills. It can also affect non-verbal memory.

Specific disorders are also linked to this part of the brain. Pick's disease causes the frontotemporal lobe to atrophy. This can lead to mood changes and loss of speech. Temporal lobe epilepsy is another chronic condition. It causes recurrent seizures and sensory hallucinations. Schizophrenia is also linked to the temporal lobe. In some cases, deficits in the left temporal lobe cause auditory hallucinations. This happens in the primary auditory cortex. Decreased gray matter can cause spontaneous neural activity. This makes the brain perceive voices that are not actually there.