Exam #3: Limbic System Flashcards
What are the general functions of the limbic structures?
- Memory
- Defense
- Reproduction
What are the major structures of the limbic system? What are the two major structures of the limbic system?
- Cingulate gyrus
- Subcallosal gyrus–located below the corpus callosum
- Parahippocampal gyrus
- Hippocampus
- Amygdala
- Septal area/ nuclei of the thalamus & hypothalamus
**Hippocampus (memory) & amygdala (emotions) are the main regions
What is the gyrus that lies above the corpus callosum?
Cingulate gyrus
Describe the shape of the amygdala.
Almond-shaped
Where are the septal nuclei?
Located on either side of the septum pellucidum in the lateral ventricle
What is the major input into the limbic system that we covered in class?
Olfaction via the olfactory tracts
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**Specifically, the lateral olfactory stria (division of the olfactory tracts) synapse with the
1) amygdala
2) primary olfactory cortex i.e. piriform lobe & uncus
What commissure carries olfactory information that crosses over?
Anterior commissure (specifically the medial olfactory stria crossover)
**Note that the anterior commissure carries sensory information from the MEDIAL olfactory stria
What is the primary portion of the olfactory cortex?
Piriform lobe
What is the entorhinal cortex?
Association cortex for olfactory information
In regards to olfaction, where does the thalamus project? What is the function of this area?
Orbitofrontal cortex–taste
What is the commissure that connects the two parts of the hippocampus?
Commissure of the fornix
What are the different parts of the hippocampus? What is an alternative name for the hippocampus?
- Pes hippocampus
- Hippoampus proper– CA 1, 2, 3
- Fornix
- Dentate Gyrus
- Subiculum
**The hippocampus is also known as the “Cornu ammonis”
Draw the path of flow through the hippocampus.
N/A
What are the different types of memory?
Working
Short-term
Long-term
Declarative
What is working memory?
Transient holding and processing of new and already stored information e.g. a phone number
What is short term memory?
This refers to a small amount of information in mind in an active, readily available state for a short period of time e.g. facts retained for min or hours with some with reinforcement
What is long-term memory?
Memories stored for decades or life via cerebral association areas
What is declarative memory?
Declarative memory refers to memories that can be consciously recalled such as facts and knowledge; it falls into two main categories
- Semantics i.e. words/ facts
- Episodic memory i.e. what you did throughout the day
What is the function of the amygdala?
Attaching emotional significance to sensory stimuli
Where do the medial stria of the olfactory tracts project?
Septal nuclei of the limbic system
Where do the amygdala and olfactory cortex project?
Entorhinal complex or “olfactory association cortex”
Where does the entorhinal cortex project?
Hippocampus
What is unusual about the olfactory pathway?
Does not project directly to the thalamus
What tract connects the amygdala to the hippocampus? What tract connects the hippocampus to the hypothalamus?
Amygdala= stria terminalis Hippocampus= fornix
