The perihippocampal fissures: normal anatomy and disease states. Tatu L, Vuillier F. Structure and vascularization of the human hippocampus. Surgical anatomy of the hippocampus.
Related articles: Anatomy: Brain. Promoted articles advertising. Figure 1: diagram Figure 1: diagram. Figure 2: human brain - lateral view Figure 2: human brain - lateral view. Figure 3: blue arrows Figure 3: blue arrows. Loading more images Close Please Note: You can also scroll through stacks with your mouse wheel or the keyboard arrow keys.
Loading Stack - 0 images remaining. By System:. Patient Cases. Contact Us. The two crua come together and form the hippocampal commissure. The hippocampal commissure provides one of two major paths whereby the hippocampi communicate with each other.
After the hippocampal commissure the single fiber bundle is properly referred to as the fornix. The fornix continues in an arc to the anterior commissure. The anterior commissure is important as a landmark because this is where the fornix splits into three parts and goes to different structures:.
Click on any of the labels to see its location identified by a green haze. It is important to remember that afferents and efferents of the hippocampus are bundled together in the same paths. Thus, by knowing the output paths, for example, you will also know the input paths, or vice versa.
Two major pathways into and out of the hippocampus are the fornix and entorhinal cortex via the cingulate cortex. The precommissural branch of the fornix connects to the septal nuclei, preoptic nuclei, ventral striatum , orbital cortex and anterior cingulate cortex. The postcommissural branch of the fornix connects to the anterior nucleus of the thalamus and the mammillary bodies of the hypothalamus.
Because the mammillothalamic tract also goes to the anterior thalamic nucleus, the hippocampus can affect the thalamus indirectly as well as directly. The anterior thalamic nuclei in turn connect to the cingulate cortex. The Papez circuit like many other areas of the limbic system is involved in learning and memory, emotion, and social behavior, and was originally thought by James Papez to the anatomical substrate of emotional experience.
The amygdala, along with neocortical areas, are now known to be centrally involved in emotional experience. Its connections to the original Papez circuit are shown in the next figure and the amygdala and emotion are discussed more thoroughly in the next section.
Note the reciprocal connections between the hippocampal formation and the association cortex, and the inclusion of the amygdala and prefrontal cortex. The hippocampus has direct connections to the entorhinal cortex via the subiculum and the amygdala. These structures connect to many other areas of the brain. The entorhinal cortex projects to the cingulate cortex. Therefore, the hippocampus can affect the cingulate cortex through the anterior thalamic nucleus or the entorhinal cortex.
The cingulate cortex, in turn, projects to the temporal lobe cortex, orbital cortex, and olfactory bulb. Thus, all of these areas can be influenced by the hippocampus. Major inputs come from the entorhinal cortex, which in turn communicate inputs from the cingulate, temporal, orbital, and olfactory cortices and amygdala to the hippocampus.
The input paths are just the reverse of the output paths. The entorhinal cortex is a major source of inputs to the hippocampus. In addition, the cingulate cortex, temporal lobe cortex, amygdala, orbital cortex, and olfactory bulb all have inputs to the hippocampus via the entorhinal cortex. The hippocampus receives inputs via the precommissural branch of the fornix from the nucleus basalis of Meynert, which is a portion of the substantia innominata and which in turn is a portion of the septal nuclei.
Also the hippocampus receives inputs via the postcommissural branch of the fornix inputs from the mammillary bodies of the hypothalamus. The medial section showing the right hemisphere. The line shows location of a cut through the left hemisphere. A blowup of the cut surface through the hippocampus shows the relationship of the hippocampal formation to the entorhinal and parahippocampal cortices.
The Influences of Emotion on Learning and Memory. Front Psychol. Navigation-related structural change in the hippocampi of taxi drivers. Remembering Preservation in Hippocampal Amnesia.
Annu Rev Psychol. Left-right dissociation of hippocampal memory processes in mice. Can physical exercise in old age improve memory and hippocampal function? Stress effects on the hippocampus: A critical review. Learn Mem. Biol Psychiatry. Aging of the cerebral cortex differs between humans and chimpanzees. Anand KS, Dhikav V. Hippocampus in health and disease: An overview. Ann Indian Acad Neurol.
Harvard Health Publishing. What is addiction? Myers DG. Exploring Psychology. New York: Worth Publishers; Your Privacy Rights. To change or withdraw your consent choices for VerywellMind.
At any time, you can update your settings through the "EU Privacy" link at the bottom of any page. 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.
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