Neuroanatomy, Hippocampus (2023)


The hippocampus is the "flash drive" of the human brain and is often associated with memory consolidation and decision making, but it is far more complex in structure and function than a flash drive. The hippocampus is a convex elevation of gray matter tissue within the parahippocampal gyrus inside the inferior temporal horn of the lateral ventricle. One can describe it more holistically as a curved and recurved sheet of the cortexthat folds into the temporal lobe's medial surface. The hippocampus has three distinct zones: the dentate gyrus, the hippocampus proper, and the subiculum—the dentate gyrus and hippocampus proper form two C-shaped rings that interlock. The subiculum is thus a transition zone, linking the hippocampus proper with the dentate gyrus. The parahippocampal gyrus and cingulate sulci are located on the medial surface of the hemisphere, forming a C-shaped ring. The medial temporal lobe cortex includes major subdivisions such as the hippocampus and the entorhinal cortex. This five-centimeter-long hippocampus (from the anterior end at the amygdala to the posterior end near the splenium of the corpus callosum) divides into a head, body, and tail.[1]the head is expanded and bears two or three shallow grooves called pes hippocampi. The head of the hippocampus is part of the posterior half of the triangular uncus and is separated inferiorly from the parahippocampal gyrus by the uncal sulcus. The alveus, which is the surface of the hippocampus, is covered by the ependymal inside the ventricular cavity.

The fornix, which is the main outflow bundle out of the hippocampus, wraps around the thalamus, where it then becomes separated by the choroidal fissure and the choroid plexus. The hippocampus contains parts like the fimbria, crus, body, and column—the fimbria forms where alveus fibers converge along the medial portion of the lateral ventricle's inferior horn. The white matter of the fimbria separates to form a crux of the ipsilateral fornix at a point beyond the splenium of the corpus callosum. The Cornu Ammonis (CA) is a seahorse-like or ram's horn-like structure that describes the different layers of the hippocampus. There are four hippocampal subfields CA1, CA2, CA3, and CA4. CA3 and CA2 border the hilus of the dentate gyrus on either side. CA3 is the largest in the hippocampus and receives fibers from the dentate granule cells on their proximal dendrites[2]. The pyramidal cell layer is about ten cells thick.

Structure and Function

Three phases of memory include (1)registration, (2) storage, and (3) retrieval of information. The hippocampus, parahippocampal region of the medial temporal lobe, and the neocortical association have been shown through the autopsy and imaging studies to be essential for memory processing. Impairment of short-term memory leading up to an inability to form new memories occurs when there is bilateral damage to the above mention regions[3]. The hippocampus is closely associated with the amygdala, hypothalamus, septum, and mammillary bodies such that any stimulation of the nearby parts also marginally stimulates the hippocampus. There are also high outgoing signals from the hippocampus, especially through the fornix into the anterior thalamus, hypothalamus, and greater limbic system. The hippocampus is also very hyperexcitable, meaning it can sustain weak electrical stimulate into a long, sustained stimulation that helps in encoding memory from olfaction, visual, auditory, and tactile senses.

In lower animals, the hippocampus helps them determine if they will eat certain foods, based on olfactory discernment, avoid danger; respond to sexual invites through pheromones, or react to life and death decisions. The hippocampus is a site for decision-making and committing information to memory for future safety uses. Thus it has a mechanism to convert short-term memory into long-term memory, consolidating the verbal and symbolic thinking into information that can be accessed when needed for decision making.


The hippocampus originates in the isocortex as part of the fifth limbic lobe of the brain in thecerebral hemisphere'smedial surface. It is also considered part of the olfactory cortex.[4]It is drawn to the temporal lobe by a strand of fibers called the fornix. Choroid fissure helps the choroid plexus invaginate into the lateral ventricle. The hippocampus itself is a mammalian innovation, while the isocortex as a whole is part of the phylogenetical ancient brain. The hippocampus is a deep structure hidden between the mesencephalon and the medial aspect of the temporal lobe. Three important changes are necessary for the complex shape and location of the hippocampus

  1. Rotation of the lateral parts of the developing telencephalon dorsocaudally, then ventrally and rostrally, forming the parietal, occipital, and temporal lobes.

  2. The hippocampal sulcus then invaginates into the medial wall of the temporal lobe

  3. Finally, the hippocampal sulcus rotates along a longitudinal axis of the hippocampus, forming a complex structure that is present in the medial aspect of the temporal lobe.

Blood Supply and Lymphatics

The anterior choroidal artery runs medially and superiorly to the uncus, between the ambient and semilunar gyrus.[1]It then sends perforating arteries to reach deeper structures. The uncus is closely related to the M1 segment of the middle cerebral arteries and its lenticulostriate arteries.

The P2 segment of the posterior cerebral artery and the basal vein supply and drain the caudal part of the head of the hippocampus that faces the crus cerebri and crural cistern.[5]

Internal cerebral veins drain into thalamostriatal basal ganglia, thalamus, internal capsule, tela choroidea of 3 ventricles, and hippocampus. The veins on each side unite to form the internal cerebral vein.

Surgical Considerations

Ahippocampectomy is a surgical procedure to excise the hippocampus in patients with medial temporal epilepsy due to hippocampal sclerosis[6]. The hippocampus is complex and has a deep location compared to other complex structures. Subpial resection of the hippocampus and perhaps some surrounding structures, like the amygdaloid complex and parahippocampal gyrus, is recommended in this procedure while avoiding lesions to important surrounding landmarks. The hippocampus is only viewable from the inferior horn of the lateral ventricle, which makes a resection especially challenging and complex.

Clinical Significance

Alzheimer's disease is accompanied by early dysfunction and loss of synapses, prominently affecting excitatory transmission in the hippocampus and cerebral cortex.[7] These changes may contribute to memory loss. The loss of neuronal population specifically glutamatergic neurons in the entorhinal cortex and pyramidal neurons of the CA1 sector of the hippocampus are also seen in Alzheimer’s disease. These pyramidal neurons of the CA1 sector are also more selectively vulnerable to global cerebral ischemia with the severity of pathology depending on the ischemic duration. These abnormalities can be seen on the CA1 field on MRI[8]. If a coma persists for less than 12 hours (brief ischemia) it might cause reversible bilateral encephalopathies to the thalamus or hippocampus. Patients with brief ischemia will present with transient confusion or amnesia upon awakening. Some patients may show severe anterograde or variable retrograde amnesia with or without confabulations.

Vascular dementia is the second most common cause of dementia after Alzheimer’s[9]. It can be caused by multiple large cortical infarcts, strategic infarcts involving the hippocampus or thalamus.


The Hind-brain or Rhombencephalon, Superficial dissection of brain-stem; Lateral view, External Capsule, Hippocampus, Superior colliculus, Inferior colliculus, Ventral Spinocerebellar fasciculus. Contributed by Gray's Anatomy Plates


Horizontal section of right cerebral hemisphere, Genu of Corpus callosum, Anterior cornua of lateral ventricle, Caudate nucleus, Septum pellucidum, Internal capsule (frontal part), Column of fornix, Genu of internal capsule, Putamen, Globus pallidus, (more...)


Diagram of the fornix, Body of Fornix, Hippocampal commissure, Crus fornicis, Fimbria, Uncus, Hippocampus, Anterior Pillars of Fornix. Contributed by Gray's Anatomy Plates



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What is the Neuroanatomy of the hippocampus? ›

The hippocampus is a convex elevation of gray matter tissue within the parahippocampal gyrus inside the inferior temporal horn of the lateral ventricle. One can describe it more holistically as a curved and recurved sheet of the cortex that folds into the temporal lobe's medial surface.

What is the hippocampus responsible for? ›

Hippocampus is a complex brain structure embedded deep into temporal lobe. It has a major role in learning and memory. It is a plastic and vulnerable structure that gets damaged by a variety of stimuli. Studies have shown that it also gets affected in a variety of neurological and psychiatric disorders.

What are 3 functions that the hippocampus controls? ›

Being an integral part of the limbic system, hippocampus plays a vital role in regulating learning, memory encoding, memory consolidation, and spatial navigation.

What does the hippocampus do quizlet? ›

The hippocampus is the structure in the brain most closely aligned to memory formation. It is important as an early storage place for long-term memory, and it is involved in the transition of long-term memory to even more enduring permanent memory.

Does the hippocampus have 6 layers? ›

The hippocampus and dentate gyrus are actually cortex, but it is 3-layered cortex rather than 6-layered cortex as in the neocortex.

What are the components of hippocampus? ›

The hippocampus, as the medial pallium, is a structure found in all vertebrates. In humans, it contains two main interlocking parts: the hippocampus proper (also called Ammon's horn), and the dentate gyrus.

What stimulates the hippocampus? ›

Aerobic exercise in particular helps boost BDNF levels and promote hippocampal function. Another study showed that light and moderate exercise increased the size of the hippocampus and enhanced memory retention.

What emotions does the hippocampus control? ›

The hippocampus, located in the medial temporal lobe and connected with the amygdala that controls emotional memory recalling and regulation (Schumacher et al., 2018); it has increased the functional connectivity with anterior cingulate or amygdala during emotional regulation and recalling of positive memory (Guzmán- ...

What does damage to the hippocampus? ›

Damage to the hippocampus can cause a condition called amnesia that prevents people from forming new memories and remembering past experiences.

Can you function without a hippocampus? ›

In short, the hippocampus orchestrates both the recording and the storage of memories, and without it, this “memory consolidation” cannot occur. After his memory vanished, H.M. lost his job and had no choice but to keep living with his parents.

How does the hippocampus store memory? ›

When a memory is created, information flows from the cortex, the part of the brain rich in nerve cells, to the hippocampus, the central switching point for memories in the brain. The information flows in the opposite direction when we retrieve a memory.

Why do we have two hippocampus? ›

Because the brain is lateralized and symmetrical, you actually have two hippocampi. They are located just above each ear and about an inch-and-a-half inside your head.

What happens to the hippocampus during sleep? ›

Hippocampal activity seems to specifically support memory consolidation during sleep, through specific coordinated neurophysiological events (slow waves, spindles, ripples) that would facilitate the integration of new information into the pre-existing cortical networks.

Is the hippocampus responsible for fight or flight? ›

The amygdala and the hippocampus are two brain structures involved in fear and traumatic stress. The amygdala detects whether a stimulus (person or event) is threatening and the hippocampus, the center of short-term memory, links the fear response to the context in which the threatening stimulus or event occurred.

How many types of neurons are in the hippocampus? ›

Systematic mining of published data on axonal and dendritic profiles, augmented with information on neurotransmitter and synaptic specificity, led to the tentative definition of over 100 distinct neuron types across the hippocampal formation.

What is CA1 in hippocampus? ›

Within the hippocampal memory system, CA1 neurons are critically involved the formation, consolidation, and retrieval of hippocampal-dependant memories. Recent high-resolution volumetry did show an association between CA1 volume and episodic memory retrieval (38).

What are some facts about the hippocampus? ›

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.

What is the hippocampus classified as? ›

The hippocampus is a small region of the brain that forms part of the limbic system and is primarily associated with memory and spatial navigation.

What hormone does the hippocampus produce? ›

Growth hormone is produced within the hippocampus where it responds to age, sex, and stress.

What exercises strengthen the hippocampus? ›

5 brain-boosting exercises
  1. Aerobic exercise. Regular aerobic exercise boosts blood flow to your brain, and also boosts the size of your hippocampus, the part of your brain that's involved in verbal memory and learning, Small says. ...
  2. Weight training. ...
  3. Yoga. ...
  4. Tai chi.
Mar 2, 2022

Does anxiety activate the hippocampus? ›

Growing evidence indicates that anxiety is associated with increased neuronal excitability in the hippocampus, and alterations in local regulation of hippocampal excitability have been suggested to underlie behavioral disruptions characteristic of certain anxiety disorders.

How can I improve my hippocampus in the brain? ›

Ten Ways To Improve Your Hippocampus Function
  1. Learn Something New. Due to the way the hippocampus works, when you learn something new, you build new neural pathways and strengthen the ones that already exist. ...
  2. Exercise. ...
  3. Eat Fish. ...
  4. Drink Coffee. ...
  5. Eat Blueberries. ...
  6. Stimulate Your Brain. ...
  7. Eat Dark Chocolate. ...
  8. Practice Mindfulness.

What role does the hippocampus play in anxiety? ›

It's also known that the hippocampus sends signals to other areas of the brain—the amygdala and the hypothalamus—that have also been shown to control anxiety-related behavior.

What part of the brain controls crying? ›

The region in question is the cingulate gyrus, also referred to as 'limbic cortex', particularly in non-primate mammals where its differentiation is less well developed.

What happens if you stimulate the hippocampus? ›

Our results indicate that stimulation of the hippocampus during encoding helped to build strong associative memories and enhanced recollection in subsequent trials. Moreover, stimulation significantly increased theta power in the lateral middle temporal cortex during successful memory encoding.

Can the hippocampus grow back? ›

Research shows that we have the capacity to grow new neurons above and beyond what is generally produced in our hippocampus and to make them become mature and strong within weeks and months. The best way to generate new hippocampal neurons is to exercise.

Does stress damage the hippocampus? ›

Chronic stress can cause long-term damage to the hippocampus. In fact, the hippocampus itself has been shown to shrink in size in people suffering from an ongoing HPA axis stress response.

What causes hippocampus to shrink? ›

Researchers have found that traumatic events and severe stress can cause shrinkage of this area of the brain, with significant changes observed in both men and women who suffer from Post-Traumatic Stress Disorder as the result of sexual assault or combat.

Can a human survive without the hippocampus? ›

Stress, memory, and the hippocampus: can't live with it, can't live without it.

What would happen if you removed your hippocampus? ›

One of the biggest risks of the hippocampus removal is the recurrence of seizures, which happens when some parts of the hippocampus and amygdala are not removed. This may mean the patient has to go through another round of surgery.

What happens to the hippocampus due to a lack of sleep? ›

Because the formation of object-location memories critically depends on proper hippocampal function [23],these findings indicate that sleep deprivation leads to memory deficits by misregulating cAMP signaling in hippocampal excitatory neurons.

Does sleep help the hippocampus? ›

Sleep deprivation impairs hippocampal synaptic plasticity. Sleep deprivation is detrimental to hippocampus-dependent memory. As the neural correlate of learning and memory, it is not surprising that sleep deprivation disrupts synaptic plasticity in the hippocampus as well.

Does alcohol destroy the hippocampus? ›

Substantial evidence suggests that one of the main targets of alcohol toxicity in the brain is the hippocampus; indeed the alcoholic population shows neuronal loss and a reduction in total hippocampal volume as shown by magnetic resonance imaging (Jernigan et al., 1991; Harper, 1998).

Are dreams stored in the hippocampus? ›

Deep inside the temporal lobe of the brain, the hippocampus has a central role in our ability to remember, imagine and dream.

What happens to the hippocampus when in love? ›

Love makes your brain light up!

MRI scans also indicated that the reward circuit—the amygdala, the hippocampus, and the prefrontal cortex—which is very sensitive to behaviours that induce pleasure, lights up on brain scans when talking about a loved one because of increased blood flow in these areas.

What is the left vs right hippocampus? ›

Right hippocampus plays a critical role in spatial memory in older adults, while the role of left hippocampus in verbal memory is more prominent.

What connects the two hippocampus? ›

Although it is often referred to in the singular, there are actually two hippocampi in the human brain—one in each cerebral hemisphere. The two hippocampi are connected via the fornix, which is a C-shaped bundle of nerve fibers that connect the hippocampi together, as well as with other structures in the brain.

What happens to the hippocampus in depression? ›

Depression causes the hippocampus to raise its cortisol levels, impeding the development of neurons in your brain. The shrinkage of brain circuits is closely connected to the reduction of the affected part's function. While other cerebral areas shrink due to high levels of cortisol, the amygdala enlarges.

Does the hippocampus store emotions? ›

Like many parts of the brain's limbic system, the hippocampus is involved in memory, learning, and emotion. Its largest job is to hold short-term memories and transfer them to long-term storage in our brains. It also plays a role in emotional processing, including anxiety and avoidance behaviors.

Does the hippocampus control motivation? ›

After reviewing the available data regarding the various effects of manipulating (e.g. lesions, chemical or electrical stimulation) the hippocampal formation, Jarrard concluded that this structure likely played a role in motivated behaviors, specifically in general behavioral activation and incentive motivation.

What is the neuroanatomy of the brain? ›

Neuroanatomy is the study of the relationship between structure and function in the nervous system. Neuroanatomy includes the study of macroscopic and microscopic structures. Macroscopic structures are larger structures, such as folds of the brain.

What does neuroanatomy include? ›

Neuroanatomy is the careful description of all of the anatomical structures in the nervous system. This includes all of the major and minor structures in the brain, the spinal cord and the nerves, the sensory and motor nerves as well as neurons and glia.

What is the purpose of neuroanatomy? ›

Neuroanatomy uses primarily visual techniques to investigate neural structure with the motivation of deducing and formulating general organizational principles, mechanisms, and structural–functional correlations.

What are the important topics in neuroanatomy? ›

arteries supplying spinal cord. spinal nerves forming cauda equina. cranial nerve attached to the medulla oblongata. cranial nerve nuclei located in medula oblongata.

How do I start studying neuroanatomy? ›

Study Tip Neuroanatomy 1.

First of all: Visualize neuroanatomy. Teaching assistants(=mentors) have passed the first course successfully and have spent a lot of time visualizing the neuroanatomy. Visualize in a way that you enjoy and 'll simultaneously learn as you have fun making the visualization.

What are the 4 main parts of the brain? ›

Lobes of the Brain and What They Control

Each brain hemisphere (parts of the cerebrum) has four sections, called lobes: frontal, parietal, temporal and occipital. Each lobe controls specific functions.

What are the 3 major parts of the brain define each? ›

The brain has three main parts:
  • The cerebrum fills up most of your skull. It is involved in remembering, problem solving, thinking, and feeling. ...
  • The cerebellum sits at the back of your head, under the cerebrum. It controls coordination and balance.
  • The brain stem sits beneath your cerebrum in front of your cerebellum.

What are the three parts of a neuro? ›

A neuron has three main parts: dendrites, an axon, and a cell body or soma (see image below), which can be represented as the branches, roots and trunk of a tree, respectively. A dendrite (tree branch) is where a neuron receives input from other cells.

What part of the brain controls emotions? ›

The limbic system controls the experience and expression of emotions, as well as some automatic functions of the body. By producing emotions (such as fear, anger, pleasure, and sadness), the limbic system enables people to behave in ways that help them communicate and survive physical and psychologic upsets.

What part of the brain controls balance? ›

The Cerebellum

This area of the brain is responsible for fine motor movement, balance, and the brain's ability to determine limb position.

What part of the brain controls smell? ›

Smells are handled by the olfactory bulb, the structure in the front of the brain that sends information to the other areas of the body's central command for further processing. Odors take a direct route to the limbic system, including the amygdala and the hippocampus, the regions related to emotion and memory.

What is the biggest question in neuroscience? ›

In a nutshell, then, the biggest unsolved problem is how the brain generates the mind, conceived of in a way that does not simultaneously require answering the problem of consciousness (Box 1).

What are the 3 most important organs in the nervous system? ›

The nervous system includes the brain, spinal cord, and a complex network of nerves. This system sends messages back and forth between the brain and the body. The brain is what controls all the body's functions. The spinal cord runs from the brain down through the back.

What is the most important part of a neuro exam? ›

The key to performing an efficient neurological examination is observation. More than half of the neurological examination is performed by simply observing the patient – how he/she speaks, thinks, walks, moves, and simply interacts with the examiner.


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