측두엽(側頭葉, temporal lobe)
측두엽은 뇌의 관자놀이 부근에 위치한 뇌의 한 부분으로, 청각 정보의 처리와 기억에 관여
측두엽의 기능
청각 정보의 처리
후각 정보의 처리
복잡한 시각 정보의 처리
얼굴 인식과 같은 대상 인식
구어 이해
기억
측두엽 손상 시 나타나는 증상 환각, 기억 장애, 실어증, 동시에 두 장소에 있는 것 같은 느낌.
측두엽 손상의 원인 뇌졸중(중풍), 측두엽에 종양이 생기는 경우.
측두엽과 관련된 질환
측두엽 간질: 측두엽에 국한되어 반복적으로 나타나는 간질
전두측두엽 치매: 전체 치매 중 약 10%를 차지하는 치매
대뇌의 엽
측두엽 이외에도 대뇌에는 전두엽, 마루엽(두정엽), 뒤통수엽(후두엽) 등
측두엽 또는 관자엽은 대뇌반구의 양쪽 가에 있는 부분으로 청각 연합영역과 청각피질이 있어 청각정보의 처리를 담당한다.
전두엽, 두정엽, 후두엽과 함께 대뇌피질을 구성한다.
형태
측두엽은 대뇌 반구의 가쪽면에서 아래쪽으로 관자극(temporal pole)으로부터 뒤통수앞패임(preoccipital notch)까지 이어져 있으며, 가쪽고랑에 의해 전두엽과 구분된다. 한편 측두엽은 대뇌 반구의 안쪽면까지도 이어져서 후각뇌고랑(rhinal sulcus) 및 곁고랑(collateral sulcus)을 경계로 변연엽과 맞닿는다. 두정엽 및 후두엽과의 구분은 다소 임의적이다. 해부학적으로 다음과 같은 세부 영역들로 구분된다.
영역
관자이랑(superior temporal gyrus): 위관자고랑(superior temporal sulcus)보다 위쪽에 존재하는 측두엽의 영역을 가리킨다.
중간관자이랑(middle temporal gyrus): 위관자고랑과 아래관자고랑(inferior temporal sulcus) 사이에 존재하는 측두엽의 영역을 가리킨다.
아래관자이랑(inferior temporal gyrus): 아래관자고랑과 뒤통수관자고랑(occipitotemporal sulcus) 사이에 존재하는 측두엽의 영역을 가리킨다.
가로관자이랑(transverse temporal gyri of Heschl): 가쪽고랑을 벌렸을 때 관찰할 수 있는 영역으로, 일차청각영역이 존재하는 부위로 알려져 있다.
방추이랑(fusiform gyrus): 대뇌 반구의 바닥면 및 안쪽면에서 관찰되는 영역으로, 뒤통수관자고랑에 의해 아래관자이랑과, 후각뇌고랑 및 곁고랑에 의해 변연엽의 해마곁이랑(parahippocampal gyrus) 및 갈고리이랑(uncus)과 구분된다.
내측두엽
내측두엽(medial temporal lobe)은 선언적 기억이나 장기 기억에 중요한 구조들을 포함한다. 선언적 기억 (declarative memory) 또는 외현적 기억은 의식되는 기억에 속하며 통사적 기억 (semantic memory), 일화 기억 (episodic memory)로 나뉜다. 내측두엽에서 장기 기억 기능에 중요한 구조는 편도체, 뇌간, 해마체와 해마 주변의 비주위(perirhinal)영역, 내비(entorhinal)영역 등을 포함한다. 해마는 기억 형성에 결정적인 기능을 하며, 해마 주위의 내측두엽 피질은 이론상 기억 저장에 중요한 역할을 하는 것으로 보인다.
동명의 동물 해마(hippocampus)와 비슷하게 생겨서 이런 이름이 붙었다. 이 그림만 봐선 별로 안 닮은 것 같지만 해마 부분만 절제한 단면을 보면 해마와 상당히 닮아있다. 해마체라고도 한다. 이 경우 좀더 확장되거나 좀더 세분화된 영역으로 다루어질 수 있다.
해마
예전 이름은 코르누 암모니스(Cornu Ammonis)이다.
기능
생긴 건 해마와 비슷하게 생겼지만, 뇌에서 상당한 중요한 부위 중 하나고, 단기기억을 해마를 통해 장기기억으로 만드는 역할을 한다. 기억과 상기(想起)에 중요한 역할을 한다. 뇌의 측두엽 안에 왼쪽뇌, 오른쪽뇌에 하나씩 모두 2개가 있으며 변연계에 속한다. 만약 해마가 손상되거나 통째로 괴사할 경우 학습이나 새로운 기억을 받아들일 수 없게 된다.
그렇지만 뇌가소성이 제대로 발휘되어 해마의 역할을 다른 뇌 부위가 그 역할을 떠 맡을 경우에는 다시 학습이 가능할 수도 있다. 허나 해마가 있을 때보다는 그 기능이 떨어질 수 있다.
해마의 기능이 밝혀진 것은 1953년으로, 밝혀진 과정이 상당히 특이한데, 과거 전두엽 절제술이 성행하던 시절, 발작환자였던 H. M.(이하 몰레이슨)은 치료를 위해 해마를 적출하게 되었다. 이 수술 이후 몰레이슨의 발작 증세는 눈에 띄게 호전되었으나, 새로운 기억을 학습하지 못한다는 사실을 추가적으로 발견할 수 있었다. 이러한 사실에 의구심을 품던 학자들에 의해 해마의 기능이 밝혀지게 된다.
The temporal lobe
The temporal lobe is a part of the brain that is located behind the ears and is involved in processing sensory information, language, and memory.
Location
The temporal lobe is one of the four major lobes of the brain's cerebral cortex
It is located on both sides of the brain, near the temples and ears
It is angled downwards and forwards to resemble the thumb of a boxing glove
Function
It helps process auditory information and encode memories
It helps process emotions, language, and certain aspects of visual perception
It helps process sensory input, including pain and auditory stimuli
It helps you understand language, retain visual memories, and process and remember emotions
Damage
Damage to the temporal lobes can result in difficulty understanding spoken words, learning and retaining new information, and more
Damage to this region of the brain can have global consequences for virtually every bodily function
Epilepsy
Temporal lobe epilepsy (TLE) can be treated with surgery, stereotactic radiosurgery, or laser ablation
What is the temporal lobe?
Your temporal lobe is a part of your brain that helps you use your senses to understand and respond to the world around you. It also plays a key role in how you communicate with other people, your ability to access memories, use language and process emotions.
Function
What does the temporal lobe do?
Your temporal lobe contains areas of your brain that manage or contribute to several of your most useful abilities: language, memory and senses. You use these abilities constantly throughout your daily activities. Your temporal lobe contributes to these in the following ways:
Memory: Inside your temporal lobe is your hippocampus, which is essential for several memory-related processes and abilities.
Language: The temporal lobe gives you the ability to understand the meaning of words and objects. For instance, when you see a cup and recognize it as a container to drink out of, your temporal lobe is at work. Your temporal lobe is also home to Wernicke’s area, a part of your brain that helps you understand language and form meaningful sentences.
Emotions: Within your temporal lobe is the amygdala (pronounced “ah-MIG-da-la”). It plays a role in how you experience and process certain emotions.
Senses: Your temporal lobe processes signals from your senses, especially sight and sound.
Visual recognition: Certain regions of your temporal lobe are key to recognizing visual material such as familiar faces and known objects.
All of the above abilities have strong connections. Your senses tell you about the world around you, your memory helps you recognize what’s familiar, your language abilities are part of how you remember and describe what you experience, and emotions are how you feel about it all.
Connections between your senses, memory, language abilities and emotions are all key to your survival. Fear and anxiety are protective emotions (they only become mental health concerns if they happen in ways that are disruptive to your life). Connections between memories and emotions help you use past experiences to recognize danger and avoid it.
Emotions also help with learning. That’s why you feel positive emotions like happiness and pleasure from rewards and good outcomes, and negative emotions like sadness and disappointment from consequences and unwanted outcomes.
Anatomy
Where is the temporal lobe located?
Like all lobes of your brain, your temporal lobe has left and right sides. The sides of your temporal lobes are the farthest apart of the brain lobes. Each temporal lobe is right behind the temple area on each side of your head, and the lobe extends backward along the side of your brain to a point just behind your ears.
What color is the temporal lobe?
Most of your brain tissue, including your temporal lobe, is a light pinkish-gray when it has blood circulating in it. Without circulating blood, brain tissue has a more grayish color.
How big is the temporal lobe?
Your temporal lobe is the second-largest of your brain’s five lobes. It makes up about 20% of the cerebral cortex of your brain. The word “cortex” comes from Latin and means “tree bark.” The cortex is the wrinkly-textured outer surface of your brain, and its average thickness is about 2.5 millimeters.
What is the temporal lobe made of?
Your temporal lobe consists of the same kinds of specialized cells found throughout your brain and nervous system. The basic cell types are:
Neurons: These are the cells in your brain and nerves that can send or relay signals to other neurons. The signals travel as electricity inside your neurons. Your neurons convert the electrical signals into chemical form and vice versa. The chemical signals are for neuron-to-neuron communication.
Glial cells: These are your nervous system’s support cells. They don’t manage signals. Instead, they maintain and support the neurons.
Key areas of the temporal lobe
The temporal lobe contains a few noteworthy areas:
The amygdala. Your amygdala manages emotions like fear and anxiety. It also contributes to how you feel when you get a reward and learning-related emotions.
The hippocampus. This seahorse-shaped part of your brain is like your brain’s memory library. It stores declarative memories, which are memories you can access, remember and describe. Declarative memories include memories of events or memorized facts and information. Your hippocampus also helps with recognition memory, which is your ability to recognize something — such as objects, sounds or faces — based on stored memories.
The fusiform gyrus (pronounced “FEW-si-form JY-rus”). This structure is a critical link between the visual processing center in your occipital lobe and your memory storage in your temporal lobe. This structure rapidly analyzes things you see and compares them to stored memories. If it can (either partially or exactly) match what you see with something from your memory, it links the memory to what you’re seeing now so you can recognize it. It’s a key area in recognizing familiar faces.
Conditions and Disorders
What are the common conditions and disorders that affect the temporal lobe?
Virtually any brain-related condition or illness can affect your temporal lobe. Some conditions, especially mental health-related conditions, may affect it very specifically. Examples include:
Alzheimer’s disease.
Certain forms of amnesia (memory loss).
Brain lesions (either from diseases or with damage from surgery or medical procedures).
Brain tumors (including cancer).
Carbon monoxide poisoning.
Concussions and other traumatic brain injuries.
Certain types of aphasia.
Frontotemporal dementia (including conditions like Pick’s disease).
Headaches and migraines.
Hippocampal sclerosis.
Poisons or toxins (such as heavy metals like lead or industrial chemicals like toluene).
Memory-linked sensory processing problems like prosopagnosia (face blindness).
Infections (including those that cause encephalitis).
Mental health conditions related to feelings of fear or panic, especially anxiety disorders or post-traumatic stress disorder (PTSD).
Lewy body dementia.
Limbic predominant age-related TDP-43 encephalopathy (LATE).
Schizophrenia.
Seizures and seizure-related conditions such as epilepsy (particularly temporal lobe epilepsy).
Stroke and transient ischemic attack (TIA).
What are some common signs or symptoms of conditions that affect the temporal lobe?
There are dozens (or more) of possible symptoms that can result from damage or disruptions in your temporal lobe. Two reasons why there are so many possible symptoms include:
Your temporal lobe contributes to many different abilities.
Many conditions can affect your brain in different ways, including disrupting your temporal lobe.
While the full list is extensive, some symptoms are more common or could indicate a dangerous issue. These include:
Memory problems.
Changes in understanding language and/or language expression (like speaking or writing).
Alexia (similar to dyslexia, but more severe, and you don’t develop it in childhood).
Acalculia (like alexia, but for numbers and math; dyscalculia is a less-severe childhood form of this).
Seizures (75% of focal seizures with loss of awareness start in your temporal lobe).
Severe or frequent feelings of anxiety or panic, including those related to disturbing or traumatic memories and experiences.
Confusion.
Changes in vision.
What are some common tests to check the health of the temporal lobe?
There are many ways healthcare providers can check the health of or look for problems in your temporal lobe. These include diagnostic tests, lab tests, imaging scans and more. Common tests include:
Blood tests (these can detect many issues, ranging from immune system problems to toxins and poisons, especially metals like copper, mercury or lead).
Computed tomography (CT) scan.
Cerebrospinal fluid tests.
Electroencephalogram (EEG).
Electromyogram (nerve conduction test).
Evoked potentials (sensory tests).
Magnetic resonance imaging (MRI).
Neurological examination.
Neuropsychological assessment.
Positron emission tomography (PET) scan.
Speech and language pathology evaluation.
What are common treatments for conditions affecting the temporal lobe?
Because so many conditions can affect your temporal lobe, the treatments can vary widely. Your healthcare provider is the best person to tell you about the possible treatments and what they recommend.
Care
What can I do to take care of my temporal lobe?
There are a number of things you can do to maintain how well your temporal lobe works, including:
Help your hearing. If you have hearing loss, it doesn’t just make it harder for you to communicate with others or listen to sounds around you. It may also contribute to memory loss, dementia and even age-related degenerative brain diseases like Alzheimer’s disease. That makes it important to see a hearing specialist, such as an audiologist, to have your hearing tested. And if you need hearing aids, use them.
Engage your brain. Your brain is like any other part of your body. To keep it healthy, you need to put it to work. Keeping your brain busy is a key way to delay age-related decline in mental abilities, especially your memory.
Get enough quality sleep. Your brain needs good, quality sleep to work correctly. Lack of sleep or poor-quality sleep can contribute to conditions like Alzheimer’s disease. A lack of quality sleep, such as with sleep apnea, can also cause thinking and memory problems (and this is true for people of all ages). Making sleep a priority is a way to make your brain health a priority.
Use tools to aid your brain. Memory aids — including calendars, planners, alarms, smartphone apps, etc. — can help bolster your thinking and memory. While it might seem like they keep you from using your brain, they can actually help your brain stay active and keep up with the world around you.
There are many other ways to help maintain your brain health overall. While many brain conditions aren’t preventable, you may be able to delay or reduce the severity of some conditions. Some things you can do for your brain health include:
Eat a balanced diet. What you eat directly impacts your circulatory system health. Your brain relies on your circulatory system (a stroke is an example of a condition that happens when circulatory problems affect your brain). Too much or too little of certain vitamins can also affect your brain.
Reach and maintain a weight that’s healthy for you, and find ways to be physically active. Managing your weight and activity level can help you prevent or delay many chronic conditions — especially circulatory issues like high blood pressure — that can impact how your brain works. Your primary care provider can guide you on reaching and staying in a weight range that’s healthy for you. Staying physically active is also good for your brain directly, as it stimulates the production of key signaling chemicals known as neurotransmitters.
Wear safety equipment as needed. Because of their location, your temporal lobes are prone to concussions and traumatic brain injuries, especially from side impacts and sudden movement changes. Helmets, safety restraints (such as seat belts) and other protective gear are essential to preventing brain injuries to your temporal lobe.
Manage your chronic conditions. Many conditions that affect your brain worsen over time. However, treating those conditions can sometimes stop them or delay how long it takes for them to worsen. Examples of conditions like this include Type 2 diabetes, epilepsy and more.
