Hippocampus Structure And Function Pdf

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hippocampus structure and function pdf

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T1-weighted image for acquisition of hippocampal volume. The borders of the hippocampus were traced manually in the coronal orientation with simultaneous monitoring for accuracy in the sagittal and axial orthogonal views.

What is the hippocampus?

The hippocampus is a part of the brain. It is found in the inner folds of the bottom middle section of the brain, known as the temporal lobe. Humans have known about the hippocampus for more than 4 centuries.

It is one of the most studied parts of the brain. The name comes from the Greek words hippo, meaning horse, and kampo, meaning monster, as its shape resembles that of a sseahorse. Its main functions involve human learning and memory. Knowing about the hippocampus has helped researchers understand how memory works. The hippocampus is part of the limbic system, which is associated with the functions of feeling and reacting.

The limbic system is situated on the edge of the cortex, and it includes the hypothalamus and the amygdala. The hippocampus helps humans process and retrieve two kinds of memory, declarative memories and spatial relationships.

Declarative memories are those related to facts and events. Examples include learning how to memorize speeches or lines in a play.

Spatial relationship memories involve pathways or routes. For example, when a cab driver learns a route through a city, they use spatial memory. Spatial relationship memories appear to be stored in the right hippocampus. The hippocampus is also where short-term memories are turned into long-term memories. These are then stored elsewhere in the brain. Research has shown that nerve cells continue to develop throughout adulthood. The hippocampus is one of the few places in the brain new nerve cells are generated.

They may be unable to remember some things that happened shortly before the hippocampal damage, but they may still remember things that happened longer ago. This is because the long-term memories are stored in another part of the brain, once they become long term. Transient global amnesia is a specific form of memory loss that develops suddenly, seemingly on its own, and then goes away fairly quickly.

Most people with transient global amnesia eventually regain their memories, but the reasons why the problem occurs and why it resolves are unclear. It may be that damage to the hippocampus is involved. Damage to the hippocampus can make it hard to remember how to get from one place to another.

The person may be able to draw a map of the neighborhood they lived in as children, but find going to a store in a new area can be difficult. It has also been linked to conditions such as schizophrenia and post-traumatic stress disorder PTSD. The hippocampus is a sensitive part of the brain.

A range of conditions can adversely affect it, including long-term exposure to high levels of stress. They may also find it difficult to follow directions. As the disease progresses, the hippocampus loses volume, and it becomes harder to function in daily life.

Autopsies have suggested that between 50 and 75 percent of people with epilepsy have damage to the hippocampus. In people with severe depression , the hippocampus loses volume.

Scientists are unsure whether the small size is the result of depression or if it is a contributing factor. There is evidence that stress has a negative impact on the hippocampus. In people with depression, the hippocampus can shrink by up to 20 percent , according to some researchers. Reviews of studies have suggested that the hippocampus in people with severe depression may be an average of 10 percent smaller than in those without depression.

One of these symptoms is a reduction in the size of the hippocampus. A study in monkeys has shown that the size of the hippocampus is 54 percent heritable. However, since the hippocampus continues to produce neurons throughout adult life, the link remains unclear. It is also unclear whether a small hippocampus is an underlying cause of certain conditions, or whether it is a result.

In , scientists published a review of studies into the effects of exercise on cognitive decline and aging. This would preserve and potentially improve memory. How this happens remains unclear, however. In addition, a number of variables affect the outcome.

More research is needed to confirm any findings. In August , researchers in Hong Kong published findings suggesting that low-frequency activities in the hippocampus can drive functional connectivity in other parts of the brain. In other words, activity in the hippocampus can affect not only memory and pathfinding, but also functions such as vision, hearing, and touch. While it is possible to die from a seizure, it is very rare. Dying solely from a seizure without secondary factors, like a fall or drowning, is even….

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What is the hippocampus? Medically reviewed by Daniel Murrell, M. Function What can go wrong? Diseases that affect the hippocampus What happens if the hippocampus is small? Current research The hippocampus is a part of the brain. Share on Pinterest The hippocampus is important for learning and memory. What can go wrong? Diseases that affect the hippocampus. What happens if the hippocampus is small?

Current research. Does body fat protect females against heart disease? Revenge bedtime procrastination: A plight of our times? Related Coverage. Can you die from a seizure? What is xeroderma pigmentosum XP? Medically reviewed by Susan Bard, MD.

Functional organization of the hippocampal longitudinal axis

Hippocampus , region of the brain that is associated primarily with memory. The hippocampus, which is located in the inner medial region of the temporal lobe, forms part of the limbic system, which is particularly important in regulating emotional responses. The hippocampus is thought to be principally involved in storing long-term memories and in making those memories resistant to forgetting, though this is a matter of debate. It is also thought to play an important role in spatial processing and navigation. The anatomy of the hippocampus is of chief importance to its function.

The hippocampus is a part of the brain. It is found in the inner folds of the bottom middle section of the brain, known as the temporal lobe. Humans have known about the hippocampus for more than 4 centuries. It is one of the most studied parts of the brain. The name comes from the Greek words hippo, meaning horse, and kampo, meaning monster, as its shape resembles that of a sseahorse. Its main functions involve human learning and memory.

Linking Hippocampal Structure and Function to Memory Performance in an Aging Population

Humans and other mammals have two hippocampi, one in each side of the brain. The hippocampus is part of the limbic system , and plays important roles in the consolidation of information from short-term memory to long-term memory , and in spatial memory that enables navigation. The hippocampus is located in the allocortex , with neural projections into the neocortex in humans, [1] [2] [3] as well as primates. In Alzheimer's disease and other forms of dementia , the hippocampus is one of the first regions of the brain to suffer damage; [7] short-term memory loss and disorientation are included among the early symptoms. Damage to the hippocampus can also result from oxygen starvation hypoxia , encephalitis , or medial temporal lobe epilepsy.

The hippocampus mediates several higher brain functions, such as learning, memory, and spatial coding. The input region of the hippocampus, the dentate gyrus, plays a critical role in these processes. Dentate gyrus granule cells receive excitatory neuron input from the entorhinal cortex and send excitatory Dentate gyrus granule cells receive excitatory neuron input from the entorhinal cortex and send excitatory output to the hippocampal CA3 region via the mossy fibers.

What is the hippocampus?

Structure, function, and plasticity of hippocampal dentate gyrus microcircuits

The brain is an amazing three-pound organ that controls all functions of the body, interprets information from the outside world, and embodies the essence of the mind and soul. Intelligence, creativity, emotion, and memory are a few of the many things governed by the brain. Protected within the skull, the brain is composed of the cerebrum, cerebellum, and brainstem. The brain receives information through our five senses: sight, smell, touch, taste, and hearing - often many at one time. It assembles the messages in a way that has meaning for us, and can store that information in our memory. The brain controls our thoughts, memory and speech, movement of the arms and legs, and the function of many organs within our body.

The limbic system is a convenient way of describing several functionally and anatomically interconnected nuclei and cortical structures that are located in the telencephalon and diencephalon. These nuclei serve several functions, however most have to do with control of functions necessary for self preservation and species preservation. They regulate autonomic and endocrine function, particularly in response to emotional stimuli.

Thank you for visiting nature. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer. In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. The currently accepted model of a dorsal—ventral posterior—anterior dichotomy of hippocampal function requires revision. Anatomical studies in rodents and primates show that hippocampal extrinsic connectivity is organized as smooth topographical gradients. The relative size of spatial representation by place cells in the rat hippocampus gradually increases from dorsal to ventral.

Chapter 9 - Limbic System

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