Copy of Volume 6 - publication


Hippocampus Structure and Functions
Violet Wang

The distinction and consistency of the Dorsal and Ventral
Hippocampus's functions.
 
"What is the name of the mythical creature with the upper
body of a horse and the lower body of a fish that came with
Poseidon?"
 "It is Hippokampos!"
 
In Greek mythology, Hippokampos means seahorse, and it
was later morphed into the English word hippocampus.
Hippocampus, a part of the brain, gets its name because of
its shape.

bottom (Moser & Moser, 1998). Moreover, previous studies
of anatomy revealed that the input and output connections
of the dorsal hippocampus and ventral hippocampus are
different (Swanson & Cowan, 1977). 

Figure 1. Comparison of the human hippocampus and
seahorse

The hippocampus is a small seahorse-shaped structure
located in the medial temporal lobe of the brain. As part of
the limbic system, it is well known for its function of
declarative memory formation, consolidation, and retrieval
(Squire, 1992). Damage or dysfunction of the hippocampus
can lead to a variety of memory impairments, such as
amnesia (Zola-Morgan et al., 1986). The hippocampus is a
highly intricate and multifaceted brain region that is not
limited to memory processing, but also encompasses a
range of other important human functions, including
emotional regulation.

Let's go back to the structure of the hippocampus. According
to the analysis by Moser and Moser (1998), the
hippocampus may not be a single entity, but rather, the
dorsal and ventral regions may have different roles. Dorsal
and ventral are anatomical terms used to describe the
relative positions of structures in the body or brain. Dorsal
refers to the upper or back side, while ventral refers to the
lower or front side. In the hippocampus, the dorsal portion is
the septal pole, which is closer to the top of the brain, while
the ventral portion is the temporal pole, which is closer to the

Figure 2. The diagram of the hippocampus. The
hippocampus is divided in the middle into dorsal hippocampus

and ventral hippocampus.

The dorsal hippocampus is associated with episodic memory
and spatial navigation. In a study by Maguire et al. (1997),
taxi drivers recalling complex routes through the city showed
different activation patterns in the right posterior
hippocampus compared to the anterior hippocampus, while
language materials preferentially activated the human
posterior hippocampus over the anterior hippocampus, with
greater activation in the left side (Greicius et al., 2003).
Anatomically, the dorsal CA1 is linked to the postpressive
and anterior cingulate cortex (Cenquizca & Swanson, 2007;
Vogt & Miller, 1983), two cortical regions primarily involved
in cognitive processing of visuospatial information and
memory, and environmental exploration (Maguire et al.,
2006; Spiers & Maguire, 2006). Overall, the dorsal region of
the hippocampus is more associated with cognitive
processes. 

The ventral hippocampus is responsible for emotions, such
as anxiety and fear. Kjelstrup et al. (2002) found that lesions
to the most ventral quarter of the rats‘ hippocampus led to
reduced defecation in brightly lit chambers, indicating a
reduction in anxiety. Additionally, studies indicate that
animals with the ventral hippocampus removed tend to
disregard cues associated with fear (Koh et al., 2009). In
human research, the ventral hippocampus is involved across
conditions of threat, safety, and conditioned inhibition, using
the pairing of threat and safety cue (Meyer et al., 2019) . In
terms of neuronal connectivity of the ventral hippocampus, it
communicates bidirectionally with the amygdala via
glutamate signaling, projecting responses to fear cues
(Jimenez et al., 2018). Due to this anatomical feature, the
ventral hippocampus is more associated with emotions.

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Although the dorsal hippocampus is thought to be more
important for spatial processing and memory, and the ventral
hippocampus is primarily responsible for fear and anxious
behavior, anatomical connections suggest a flow of
information between the dorsal and ventral regions (Lee et
al. 2019). It was found that in spatial performance, the dorsal
hippocampus was mainly involved in the formation of spatial
maps, while the ventral hippocampus was involved in spatial
flexibility and the ability to update spatial maps (Lee et al.
2019). When dealing with fear, the dorsal CA3 results in the
formation of a generalized fear response; the ventral CA3
leads to fear discrimination between the fear-inducing and
safe contexts (Besnard et al.,2020). In practice, the dorsal
and ventral hippocampus function as a single integrated
structure.

In summary, both the dorsal and ventral regions of the
hippocampus, which are “the head and tail” of the
hippocampus, work separately and together to facilitate
various cognitive functions to enhance quality of life.

Besnard, A., Miller, S. M., & Sahay, A. (2020). Distinct
dorsal and ventral hippocampal CA3 outputs govern
contextual fear discrimination. Cell reports, 30(7), 2360-
2373.
Cenquizca, L. A., & Swanson, L. W. (2007). Spatial
organization of direct hippocampal field CA1 axonal
projections to the rest of the cerebral cortex. Brain
research reviews, 56(1), 1-26.
Fanselow, M. S., & Dong, H. W. (2010). Are the dorsal
and ventral hippocampus functionally distinct
structures?. Neuron, 65(1), 7-19.
Greicius, M. D., Krasnow, B., Boyett‐Anderson, J. M.,
Eliez, S., Schatzberg, A. F., Reiss, A. L., & Menon, V.
(2003). Regional analysis of hippocampal activation
during memory encoding and retrieval: fMRI study.
Hippocampus, 13(1), 164-174.
Jimenez, J. C., Su, K., Goldberg, A. R., Luna, V. M.,
Biane, J. S., Ordek, G., ... & Kheirbek, M. A. (2018).
Anxiety cells in a hippocampal-hypothalamic circuit.
Neuron, 97(3), 670-683.
Kjelstrup, K. G., Tuvnes, F. A., Steffenach, H. A.,
Murison, R., Moser, E. I., & Moser, M. B. (2002).
Reduced fear expression after lesions of the ventral
hippocampus. Proceedings of the National Academy of
Sciences, 99(16), 10825-10830.
Koh, M. T., Wheeler, D. S., & Gallagher, M. (2009).
Hippocampal lesions interfere with long-trace taste
aversion conditioning. Physiology & behavior, 98(1-2),
103-107.
Lee, S. L., Lew, D., Wickenheisser, V., & Markus, E. J.
(2019). Interdependence between dorsal and ventral
hippocampus during spatial navigation. Brain and
behavior, 9(10), e01410.

References
1.

2.

3.

4.

5.

6.

7.

8.

Maguire, E. A., Nannery, R., & Spiers, H. J. (2006).
Navigation around London by a taxi driver with bilateral
hippocampal lesions. Brain, 129(11), 2894-2907.
Meyer, H. C., Odriozola, P., Cohodes, E. M., Mandell, J.
D., Li, A., Yang, R., ... & Gee, D. G. (2019). Ventral
hippocampus interacts with prelimbic cortex during
inhibition of threat response via learned safety in both
mice and humans. Proceedings of the National Academy
of Sciences, 116(52), 26970-26979.
Moser, M. B., & Moser, E. I. (1998). Functional
differentiation in the hippocampus. Hippocampus, 8(6),
608-619.
Moser, M. B., Moser, E. I., Forrest, E., Andersen, P., &
Morris, R. (1995). Spatial learning with a minislab in the
dorsal hippocampus. Proceedings of the National
Academy of Sciences, 92(21), 9697-9701.
Spiers, H. J., & Maguire, E. A. (2006). Thoughts,
behaviour, and brain dynamics during navigation in the
real world. Neuroimage, 31(4), 1826-1840.
Squire, L. R. (1992). Memory and the hippocampus: A
synthesis from findings with rats, monkeys, and humans.
Psychological Review, 99(2), 195–231.
Swanson, L. W., & Cowan, W. M. (1977). An
autoradiographic study of the organization of the efferent
connections of the hippocampal formation in the rat.
Journal of Comparative Neurology, 172(1), 49-84.
Vogt, B. A., & Miller, M. W. (1983). Cortical connections
between rat cingulate cortex and visual, motor, and
postsubicular cortices. Journal of Comparative
Neurology, 216(2), 192-210.
Zola-Morgan, S., Squire, L. R., & Amaral, D. G. (1986).
Human amnesia and the medial temporal region:
enduring memory impairment following a bilateral lesion
limited to field CA1 of the hippocampus. The Journal of
neuroscience : the official journal of the Society for
Neuroscience, 6(10), 2950–2967.

9.
 

 
10.

 
 
 
 
 

11.
 
 

12.
 
 
 

13.
 
 

14.
 
 

15.
 
 
 

16.
 
 
 

17.

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