Hippocampus Function: What Does It Do?

The hippocampus is a central structure within the brain of vertebrates, responsible for handling the storage of memories and the linking of memories to sensations. Another function of the hippocampus is aiding in navigation by enabling spatial memory.

There are two hippocampi in the brain, one in each cerebral hemisphere. The hippocampus is vaguely shaped like a horseshoe, and what bridges the two halves of the hippocampus is a long arch made out of nerve fibers and referred to as fornix.

The hippocampus is located in the temporal lobes of the brain. Without the hippocampus, people wouldn’t be able to link sounds and smells to memories or retrieve the right memories from long-term storage when they are needed.

Structure Of The Hippocampal Formation

The hippocampal formation is located within the temporal lobes and it contains the hippocampus and surrounding material. It is made out of interleaved layers of the cornu ammonis (Ammon’s horn) and dentate gyrus. The subiculum and gyri that make up the folds form the hippocampal formation.

The dentate gyrus is tucked back into the hippocampal sulcus, and at the dentate gyrus is responsible for neurogenesis. Neurogenesis is the formation of new neurons, and this critical area receives information from other brain regions in order to construct the new neurons. Neurogenesis is needed for learning and memory formation, as well as the formation of spatial memory, which allows us to navigate the world around us.

Meanwhile, Ammon’s Horn (AKA the cornu ammonis or hippocampus major) consists of three different subsections: CA1, CA2, and CA3. These areas are responsible for receiving and processing the information that arrives from other parts of the brain. Ammon’s horn is intertwined with the subiculum and the subiculum functions as the primary output system of the hippocampus. The hippocampal region is enveloped by a greater area called the parahippocampal gyrus, and it is connected to it through the subiculum.

Functions Of The Hippocampus

 

The hippocampus surrounded by other structures of the brain which are part of the limbic system. Note the hippocampus’ proximity to the amygdala and the thalamus. Photo: OpenStax College via Wikimedia Commons, CC-BY 3.0

The hippocampus plays an important role in a few vital brain functions. The hippocampus is involved in the consolidation of new memories, or the transcription of memories from short-term memory to long-term memory. Without this ability, we would not be able to learn and create new memories. The hippocampus is also heavily involved in spatial perception and memory – the perception of information about one’s surroundings and the translation of this perception into memories about those locations.

When memories are formed within the hippocampus, they are often associated with various stimuli such as smell, sights, sounds. The hippocampus also controls emotional responses to similar stimuli. When memories and emotions are strongly linked together with certain stimuli, re-experiencing these stimuli will often conjure a memory linked with them, courtesy of the hippocampus. It accomplishes the intertwining of long-term memories and emotions by working with the amygdala (the hippocampus is also located adjacent to the amygdala).

Damage Of The Hippocampus

The hippocampus surrounded by the various gyri and horns. Photo: Public Domain via Wikimedia Commons

Damage to the hippocampus can result in various memory and cognitive disorders. The primary symptom of damage to the hippocampus is difficulty retrieving memories, being unable to recall memories from storage. Diseases can impact the hippocampus in different ways. For example, Alzheimer’s disease causes tissue loss of the hippocampus, and research into the state of the hippocampus within Alzheimer’s patients has found that Alzheimer’s patients who still have good cognitive abilities have larger hippocampi than those who have developed dementia.

However, while the hippocampus is related to disorders of memory recall, it is also linked with other disorders like epilepsy and Posttraumatic Stress Disorder. Individuals with epilepsy who experienced chronic seizures are also frequently victims of retrograde amnesia and other memory issues. As for the relation of the hippocampus to Posttraumatic Stress Disorder, it is thought that sustained emotional stress can lead to the degradation of neurons within the hippocampus, brought about by the continued release of cortisol by the body in reaction to stress.

Abuse of alcohol can also damage the hippocampus over time. Alcohol has a scattershot effects on the neurons within the hippocampus, activating some receptors while suppressing others. These steroids that are manufactured by neurons under this condition lead to difficulty forming memories and learning, which is the presumed cause of blackouts from heavy drinking. Heavy drinking over long periods of time is also thought to lead to tissue loss, and MRI scans done on alcoholics reveals that they typically have a shrunken hippocampus in comparison to those who don’t drink as heavily.’

The hippocampus tends to degrade as people age, with some studies reporting shrinkage of the hippocampus observed in the elderly compared with the young. Other studies have challenged these findings, although shrinkage of the hippocampus remains heavily tied to memory issues. It is suggested that physical activity can help prevent the hippocampus from degrading during age, and one study found that the even a mild amount of physical activity almost immediately improves memory function.

Recent Research Into The Hippocampus

Recent research into the hippocampus suggests that low-frequency activities within the structure augment sensory responses and enhance conductivity between the different regions of the brain. It is thought that low-frequency activations of the hippocampus help the different parts of the brain integrate with one another and share information, as revealed in experiments done on rodents. FMRI studies done on rodents imply that the thalamus, which has many connections with the hippocampus, initiates neural interactions at various frequencies across the entire brain. Low-frequency activation of the hippocampus is also thought to enhance learning and memory, and the same frequencies are present during slow wave sleep, which is associated with the consolidation of memory and the process of learning.

Other recent studies of the hippocampus have found possible “bravery cells” within the structure. OLM cells, present within the hippocampus, appear to influence both anxiety and risk-taking behaviors, and the stimulation of the cells can influence behavior in different ways. The hippocampus’ association with anxiety is also thought to be an influence on decision-making when weighing what actions should be taken to avoid conflict. Approach avoidance-conflict occurs when a situation can result in either a punishing or rewarding stimuli, and analysis of the anterior hippocampus suggests it’s particularly responsive to conflict and that it could be tied to a larger network that processes decisions relating to conflict.

About The Author

Daniel Nelson

Daniel obtained his BS and is pursuing a Master's degree in the science of Human-Computer Interaction. He hopes to work on projects which bridge the sciences and humanities. His background in education and training is diverse including education in computer science, communication theory, psychology, and philosophy. He aims to create content that educates, persuades, entertains and inspires.

Speak Your Mind!

READ THIS NEXT

Idiopathic Normal Pressure Hydrocephalus Should Be Increasingly Recognized: Results From A Population-Based Prevalence Study

This study is the first prospective, population-based prevalence study particularly designed for idiopathic normal pressure hydrocephalus (iNPH). The finding of a 3.7% prevalence among individuals aged 65 years and older confirms that iNPH is a fairly common condition. This prevalence is higher than in previous reports, probably because the disorder was screened for with questionnaires […]

Your Uncovered Lightbulbs Exposes Your Food To Chemical Hazards

Uncovered lightbulbs expose your food to the hazard of a broken lightbulb and to potential chemical contamination. Food hazards are increasingly worrying. Although awareness of the possible hazards continues to grow, there is still a lot of information that most people are not familiar with yet. Many people, for example, are not aware that uncovered […]

Closing The Gaps In Photovoltaic Forecasting Methods

A photovoltaic (PV) value is the voltage output generated by solar cells that harvest solar energy to produce electricity. The PV value is a critical performance indicator of solar panels consisting of a plurality of solar cells (Fig. 1a). Appropriate PV forecasting over time can help PV farms/plants efficiently supply the solar energy for power […]

Structuring Data Sets By Defining Topological Relations: The Example Of Word Morph

Some years ago we got a request by language therapists if we could construct a computer program for patients with difficulties of word finding. The therapists had already successfully used the well-known language game “Word Morph” to increase the language abilities of their patients. Word Morph is a game similar to “Scrabble”: Its basic rule […]

Electrochemical Sensors For Clinical Diagnosis: Advantages Of The Miniaturization And Portability Of Devices

The diagnosis of a disease is of vital importance because early identification can help the treatment to conclude successfully. For this, analytical methods capable of detecting the substances that directly or indirectly participate in the disease, are required. Therefore, since the last century, scientific researchers have made great efforts to develop analytical methods able to […]

Phenotypic Plasticity Of Morphoanatomical Features Facilitate The Invasion Of Alligator Weed

Alligator weed (Alternanthera philoxeroides, Amaranthaceae) is one of the more famous invasion plants in the world, colonizing in aquatic and dry terrestrial environments, and it is native to the temperate regions of South America. Alligator weed invades into various temperate and subtropical environments successfully, a phenomenon which has been well studied of due to its […]

Difference Between Mitosis And Meiosis

The difference between mitosis and meiosis is in the process by which each form daughter cells from a parent cell. Mitosis has one round of cellular division and genetic separation whereas meiosis has two rounds. The two processes are also different because in mitosis the daughter cells are exactly identical to the parent cells compared […]