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FNS 4: Limbic
Neuro Lecture 4: Limbic System + Emotion
Question | Answer |
---|---|
What are the 3 biggest main anatomical/functional structures of the limbic system? | Hippocampus, Amygdala, Diffuse Neuromodulatory Transmitter Systems |
Where is the Hippocampus in relation to the gross brain? | deep to the parahippocampal gyrus (seen on the inferior brain surface) or deep to the medial temporal lobes (in coronal cross section) |
What are the 3 related structures of the hippocampal formation? | DG, CA, and Sub |
What are the subfields of the CA? | CA1-CA4 (1 and 3 are most prominent) |
As the fornix extends rostrally from the hippocampus, some fibers “peel off” and pass in front of which structure? What do they innervate? | in front of the anterior commissure (hence pre-commisural) to innervate the septum |
What are the structures (in order) of the hippocampal circuitry? | limbic association cortex- parahippocampal gyrus- DG- CA3- CA1- Sub- limbic association cortex/extorhinal cortex/mamillary bodies |
What is step 1 in the Trisynaptic Pathway? Name the pathway and the structures it connects | Perforant Path connects the parahippocampal gyrus with the dentate gyrus |
What is step 2 in the Trisynaptic Pathway? Name the fibers and the structures they connect | Mossy fibers connect the dentate gyrus and CA3 |
What is step 3 in the Trisynaptic Pathway? Name the fibers and the structures they connect | Schaeffer Collaterals connect CA3 and CA1 |
What is the “input” structure of the hippocampal formation? What is the output structure? | input= DG, output= Subiculum |
What did Donald Hebb (1949) postulate? | the cognitive process called LEARNING must have a cellular correlate |
What is Hebbian plasticity? | a growth/process/metabolic change takes place with learning; the actual brain structure changes with repeated firing |
What happened (in Hebb’s study) due to the tetanus? | strength of CA3-CA1 connection was enhanced |
What is the main or basic function of the hippocampus? | formation of new long-term declarative memories |
What is a declarative memory? | a memory that is available to consciousness and (typically) describable by language |
What is a semantic memory? | Categorical (what a bicycle looks like) |
What is an episodic memory? | Narrative (what I did this morning) |
What is the possible physiological correlate of memory consolidation? | LTP within the trisynaptic pathway |
Are non-declarative memories related to hippocampus function? | nope! These are acquired skills/associations that are largely unconscious and not describable |
What was the purpose of H.M.’s surgery? What did they do? | relief of temporal lobe epilepsy by removing most of the medial temporal lobes bilaterally |
Was H.M.’s IQ affected by his surgery? | no |
What was H.M.’s new deficit due to the surgery? | severe anterograde amnesia- inability to form new long-term declarative memories |
Were H.M.’s memories from before the surgery affected? What does this indicate to us? | no- the hippocampus is not where memories are stored |
Aging is associated with what overall brain process? Which structures are particularly affected? | Atrophy of several brain regions, particularly medial temporal lobes |
What *big picture* process is a consistent correlate of age-related cognitive decline and Alzheimer’s disease? | hippocampal atrophy |
What statistic of Americans over age 71 have some type of dementia? | 1 in 7 |
What “diagnosis” precedes Alzheimer’s disease? | Mild cognitive impairment |
What is the first brain region to show neurodegeneration in AD? | parts of the hippocampus and associated parts of the temporal lobe cortex |
How severe is AD that is associated with widespreas cortical involvement? | Moderate-severe |