The temporal lobes of the brain may not seem like much at first glance: The thumb-shaped areas at the sides of your brain aren't as large as the frontal or parietal lobes, and they aren't referenced or discussed as often as the cerebellum positioned just below. However, these oft-overlooked lobes are one of the most important parts of your brain. Without them, you wouldn't be able to remember reading this paragraph 15 minutes from now – and without the left side of your temporal lobe, you wouldn't be able to read it in the first place. This is because, in addition to a number of other critical mental functions, the temporal lobe controls language and memory. The left side in particular is home to a number of unique areas worth paying attention to.
TL;DR (Too Long; Didn't Read)
The temporal lobes of the human brain are in charge of a wide variety of functions: The lobes control memory, sound processing and facial recognition, and temporal lobe damage has been known to impact a person's personality in addition to impairing these functions. Left temporal lobe function in particular is critical for the understanding and use of language, as that lobe is home to Broca and Wernicke's areas.
Basic Temporal Lobe Function
The temporal lobes are located at the sides of the brain, and can be considered the "middle" region of each brain hemisphere. As a whole, the temporal lobe is the part of your brain in charge of memory storage, the process of hearing sounds, visual recognition of faces and objects, and the use of language. Though this seems like an incredible number of functions for one small part of the brain to command, the temporal lobes are actually more complex than they look; they contain a number of specialized substructures, including the amygdala and auditory cortex, that perform a variety of high-level functions. At the same time, the temporal lobes aren't the only parts of the brain used in many of these mental processes – the frontal and parietal lobes make sense of processed sounds for example, and the hippocampus creates the memories that the temporal lobe then stores and recalls.
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Left and Right Lobes
Though the brain appears to be symmetrical, the various lobes of the brain – the temporal lobes included – do not function the same way on each side. Instead, the left and right lobes perform different functions, communicating with the other side through the corpus callosum that connects the two hemispheres of the brain. In most people, the left side of the brain is the dominant one, and in most people the left temporal lobe controls memories related to facts and information, along with the ability to recognize faces and objects. It also controls your ability to create and understand language, through the use of two specific regions of the left temporal lobe.
Broca and Wernicke's Areas
Located at the front and middle of the left temporal lobe, respectively, Broca's area and Wenicke's area are the regions of the human brain that handle the formation and processing of language. Regardless of what language you're using, these two regions allow you to form sentences, understand the meaning of what others are saying and pick up on verbal patterns. These regions are the reason why a left temporal lobe hemorrhage can leave a person unable to understand what someone is saying, or lead them to babble incoherently.
Brain Damage, Aphasias and Agnosias
Damage to the temporal lobe, and the left (or right, if the right side of the brain is dominant) temporal lobe in particular, can be debilitating. Most often, you see this result in an inability to recall memories or information, but when certain regions of the dominant temporal lobe are damaged, such as Broca or Wernicke's areas, a certain type of brain damage known as an aphasia or an agnosia can develop. These forms of brain damage result in an inability to process a specific type of information. For example, someone with Broca's aphasia alone can understand language but will have trouble speaking – their sentences will seem garbled, but will still carry meaning. Whereas an agnosia can result in someone being unable to recognize someone's face, or can lead to them misinterpreting what a given object is. These forms of brain damage can be adapted to and lived with but are one of the many reasons it's important to protect your head from harm.