Week 4.3: Hippocampus Flashcards
What is the primary function of the hippocampus?
Memory formation, particularly explicit (declarative) memory.
Where is the hippocampus located?
In the temporal horn of the lateral ventricle, forming a bulge in the ventricular floor.
Why is the hippocampus named ‘hippocampus’?
It is named after its resemblance to a sea horse.
What are the three main parts of the hippocampus?
Dentate gyrus, hippocampus proper (Ammon’s horn), and subiculum.
What is the major input into the hippocampus?
The entorhinal cortex, which serves as a gateway to the hippocampus.
What is the major output from the hippocampus?
The fornix, which leads to the mamillary bodies of the hypothalamus.
What is the function of the fornix?
It connects the hippocampus to the mamillary bodies, forming a key part of the Papez circuit.
Where do the fornix fibers terminate?
In the mamillary bodies of the hypothalamus.
What is the Papez circuit?
A circuit involved in memory, connecting the hippocampus to the mamillary bodies, thalamus, cingulate gyrus, and entorhinal cortex.
How does the hippocampus contribute to memory storage?
It repeatedly sends signals through the Papez circuit to store important information in the cerebral cortex for long-term memory.
What type of memory is associated with the hippocampus?
Episodic memory (personal experiences) and spatial memory (navigational skills).
What is the difference between episodic and semantic memory?
Episodic memory is personal and experience-based, while semantic memory involves abstract knowledge and facts.
What role does the hippocampus play in navigation?
It stores spatial maps to help us navigate familiar environments.
How does the hippocampus affect the brain of a taxi driver?
It is significantly larger in licensed London taxi drivers due to the need for spatial navigation.
What are the consequences of a bilateral lesion to the hippocampus?
Anterograde amnesia (inability to form new memories), retrograde amnesia (loss of pre-existing memories), and a marked deficit in episodic memories.
What is anterograde amnesia?
Inability to form new memories after a brain injury.
What is retrograde amnesia?
Loss of some pre-existing memories, usually those closest to the time of injury.
What structure is part of the Papez circuit, connecting the hippocampus to the hypothalamus?
The fornix.
What structure in the Papez circuit receives input from the mamillary bodies?
The anterior thalamic nucleus.
Where does information from the anterior thalamic nucleus travel to complete the Papez circuit?
To the cingulate gyrus, and then to the entorhinal cortex.
