Temporal lobe

The temporal lobe is a region of the cerebral cortex that is located beneath the lateral fissure on both cerebral hemispheres of the mammalian brain.

The temporal lobes are involved in the retention of visual memories, processing sensory input, comprehending language, storing new memories, emotion, and deriving meaning.

Visual memories
The temporal lobe contains the hippocampus and plays a key role in the formation of explicit long-term memory modulated by the amygdala.

Processing sensory input

 * Auditory: Adjacent areas in the superior, posterior, and lateral parts of the temporal lobes are involved in high-level auditory processing. The temporal lobe is involved in primary auditory perception, such as hearing, and holds the primary auditory cortex. The primary auditory cortex receives sensory information from the ears and secondary areas process the information into meaningful units such as speech and words. The superior temporal gyrus includes an area (within the lateral fissure) where auditory signals from the cochlea first reach the cerebral cortex and are processed by the primary auditory cortex in the left temporal lobe.


 * Visual: The areas associated with vision in the temporal lobe interpret the meaning of visual stimuli and establish object recognition. The ventral part of the temporal cortices appear to be involved in high-level visual processing of complex stimuli such as faces (fusiform gyrus) and scenes (parahippocampal gyrus). Anterior parts of this ventral stream for visual processing are involved in object perception and recognition.



Language comprehension
The left temporal lobe holds the primary auditory cortex, which is important for the processing of semantics in both speech and vision in humans. Wernicke's area, which spans the region between temporal and parietal lobes, plays a key role (in tandem with Broca's area in the frontal lobe) in speech comprehension. The functions of the left temporal lobe are not limited to low-level perception but extend to comprehension, naming, verbal memory.

New memories
The medial temporal lobes (near the sagittal plane) are thought to be involved in encoding declarative long term memory. The medial temporal lobes include the hippocampi, which are essential for memory storage, therefore damage to this area can result in impairment in new memory formation leading to permanent or temporary anterograde amnesia.

Medial temporal lobe
The medial temporal lobe consists of structures that are vital for declarative or long-term memory. Declarative (denotative) or explicit memory is conscious memory divided into semantic memory (facts) and episodic memory (events). Medial temporal lobe structures that are critical for long-term memory include the amygdala, brainstem, and hippocampus, along with the surrounding hippocampal region consisting of the perirhinal, parahippocampal, and entorhinal neocortical regions. The hippocampus is critical for memory formation, and the surrounding medial temporal cortex is currently theorized to be critical for memory storage. The prefrontal and visual cortices are also involved in explicit memory.

Research has shown that lesions in the hippocampus of monkeys results in limited impairment of function, whereas extensive lesions that include the hippocampus and the medial temporal cortex result in severe impairment.