Related topics: brain · memory · neurons · brain regions · brain structure

How a bat's brain navigates

Most of what we know about how the hippocampus, a region of the brain associated with memory formation and spatial representations, comes from research done on rodents. Rat brains have taught us a lot, but researchers in ...

'Inner GPS' of bird brains may be better than that of humans

The 2014 Nobel Prize for Physiology and Medicine was awarded to three neuroscientists for their pioneering work on the brain's "inner GPS system". Over the course of four decades, they revealed that a small part in the brain ...

New nerve cells -- even in old age

After birth the brain looses many nerve cells and this continues throughout life - most neurons are formed before birth, after which many excess neurons degenerate. However, there are some cells that are still capable of ...

To make memories, new neurons must erase older ones

Short-term memory may depend in a surprising way on the ability of newly formed neurons to erase older connections. That's the conclusion of a report in the November 13th issue of the journal Cell that provides some of the ...

Birds in captivity lose hippocampal mass

( -- Being in captivity for just a few weeks can reduce the volume of the hippocampus by as much as 23 percent, according to a new Cornell study.

Building memories with actin

Memories aren't made of actin filaments. But their assembly is crucial for long-term potentiation (LTP), an increase in synapse sensitivity that researchers think helps to lay down memories. In the July 13, 2009 issue of ...


The hippocampus is a major component of the brains of humans and other mammals. It belongs to the limbic system and plays important roles in long-term memory and spatial navigation. Like the cerebral cortex, with which it is closely associated, it is a paired structure, with mirror-image halves in the left and right sides of the brain. In humans and other primates, the hippocampus is located inside the medial temporal lobe, beneath the cortical surface. Its curved shape reminded early anatomists of the horns of a ram (Cornu Ammonis), or a seahorse. The name, in fact, was taken by the sixteenth century anatomist Julius Caesar Aranzi from the Greek word for seahorse (Greek: ιππος, hippos = horse, καμπος, kampos = sea monster).

In Alzheimer's disease the hippocampus is one of the first regions of the brain to suffer damage; memory problems and disorientation appear among the first symptoms. Damage to the hippocampus can also result from oxygen starvation (hypoxia), encephalitis, or medial temporal lobe epilepsy. People with extensive hippocampal damage may experience amnesia—the inability to form or retain new memories.

In rodents, the hippocampus has been studied extensively as part of the brain system responsible for spatial memory and navigation. Many neurons in the rat and mouse hippocampus respond as place cells: that is, they fire bursts of action potentials when the animal passes through a specific part of its environment. Hippocampal place cells interact extensively with head direction cells, whose activity acts as an inertial compass, and with grid cells in the neighboring entorhinal cortex.

Because of its densely packed layers of neurons, the hippocampus has frequently been used as a model system for studying neurophysiology. The form of neural plasticity known as long-term potentiation (LTP) was first discovered to occur in the hippocampus and has often been studied in this structure. LTP is widely believed to be one of the main neural mechanisms by which memory is stored in the brain.

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