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The hippocampus (pl.: hippocampi; via Latin from Greek ἱππόκαμπος, 'seahorse') is a major component of the brain of humans and other vertebrates.Humans and other mammals have two hippocampi, one in each side of the brain.
The Great Hippocampus Question was a 19th-century scientific controversy about the anatomy of ape and human uniqueness. The dispute between Thomas Henry Huxley and Richard Owen became central to the scientific debate on human evolution that followed Charles Darwin 's publication of On the Origin of Species .
The following table gives information on the number of neurons estimated to be in the sensory-associative structure: the cerebral cortex (aka pallium) for mammals, the dorsal ventricular ridge ("DVR" or "hypopallium") of the pallium for birds, and the corpora pedunculata ("mushroom bodies") for insects.
A seahorse (also written sea-horse and sea horse) is any of 46 species of small marine bony fish in the genus Hippocampus. "Hippocampus" comes from the Ancient Greek hippókampos ( ἱππόκαμπος ), itself from híppos ( ἵππος ) meaning "horse" and kámpos ( κάμπος ) meaning "sea monster" [ 4 ] [ 5 ] or "sea animal". [ 6 ]
The horned appearance of the hippocampus is caused by cell density differentials and varying degrees of neuronal fibers. In rodents, the hippocampus is positioned so that, roughly, one end is near the top of the head (the dorsal or septal end) and one end near the bottom of the head (the ventral or temporal end).
In mammals, the pallium evolves into a complex six-layered structure called neocortex or isocortex. [62] Several areas at the edge of the neocortex, including the hippocampus and amygdala, are also much more extensively developed in mammals than in other vertebrates. [61]
The amount of time required to generate all the neurons of the CNS varies widely across mammals, and brain neurogenesis is not always complete by the time of birth. [3] For example, mice undergo cortical neurogenesis from about embryonic day (post-conceptional day) (E)11 to E17, and are born at about E19.5. [9]
The six-layered neocortex found in mammals is evolutionarily derived from a three-layer cortex present in all modern reptiles. [69] This three-layer cortex is still conserved in some parts of the human brain such as the hippocampus and is believed to have evolved in mammals to the neocortex during the transition between the Triassic and ...