Limbic System

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flucas
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18662
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Limbic System
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2010-05-24 01:53:51
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neuroscience limbic system neuroanatomy HUBIO Felicia Lucas project neuro
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Limbic System (HUBIO 532)
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  1. Which structure in the limbic system is responsible for learning and maintenance of a link between a stimulus and its emotional value?
    amygdala
  2. What is the output tract of the amygdala called (as a structure) and where is its termination?
    • stria terminalis
    • terminates in thalamus/hypothalamus
  3. What are the output fibers of the hippocampus called (as a structure) and where does it terminate?
    • fornix (fimbria anteriorly)
    • terminates in hypothalamus
  4. What are the components of the limbic system?
    • 1. limbic lobe
    • 2. septal nuclei
    • 3. amygdala
    • 4. hippocampus
    • 5. (nucleus accumbens)
  5. What structure is just deep to the uncus?
    amygdala
  6. What structure is immediately deep to the parahippocampal gyrus?
    hippocampus
  7. What are the components of the "reward system"?
    • 1. nucleus accumbens
    • 2. medial forebrain bundle (MFB)
    • 3. septal nuclei
    • 4. hypothalamus
    • 5. frontal cortex
    • 6. ventral tegmental area (VTA) in midbrain
  8. Which structure is the dentate gyrus associated with?
    hippocampus

    dentate gyrus = characteristic dark staining "spiral" formation in cross-section
  9. What structure in the limbic system is responsible for learning and declarative memory (memory for facts, events, faces, places, etc.)?
    hippocampus
  10. What happens when a person undergoes a bilateral medial temporal lobotomy? Which damaged/lesioned structure in specific is responsible for the effects?
    syndrome: Kluver-Bucy

    • symptoms:
    • -placid, flat affect
    • -fearless
    • -inappropriate social and sexual behavior (hypersexuality in animals, not humans)
    • -hyperoral and overly curious
    • -visual agnosia
    • -memory loss

    damaged/lesioned structure responsible for effects: amygdala
  11. True or false: The hippocampus (especially CA1 cells) and the globus pallidus are particularly vulnerable to damage by anoxia.
    true
  12. Which of the following statements about the hippocampus is FALSE?

    a. the hippocampus, especially CA1 cells, is particularly sensitive to enviornmental toxins, anoxia, and stress (i.e. prolonged cortisol exposure)
    b. bilateral removal of the hippocampus affects a person's IQ and their ability to consolidate/lay down new declaritive memories
    c. the hippocampus is integral in long term potentiation of memory
    d. new neurons are born in the adult hippocampus
    e. the hippocampus is postero-lateral to the amygdala
    • b. bilateral removal of the hippocampus affects a person's IQ and their
    • ability to consolidate/lay down new declaritive memories
  13. What is the function of the hypothalamus?
    • Homeostasis via
    • Endocrine system regulation
    • ANS regulation &
    • Limbic system regulation
  14. What gives input to the hypothalamus?
    • - non-neuronal inputs
    • - brainstem (input/output)
    • - retina
    • - rostral limbic structures (input/ouptput)
    • - cerebral cortex (ouput via thalamus)
  15. In what area of the brain is the limbic lobe?
    • - most medial part of temporal lobe
    • - C-shaped medial border of hemisphere
  16. What structures make up the limbic lobe?
    • - septal nuclei
    • - subcallosal gyrus
    • - cingulate gyrus
    • - isthmus of the cingulate gyrus
    • - parahippocampal gyrus
    • - uncus
  17. What are the two major sources of ACH in the brain?
    • septal nuclei
    • basal nucleus of forebrain
  18. What types of behavior are affected by lesioning the septal nuclei?
    • rage behavior
    • hyperemotionality
    • foraging
    • alteration in sexual behavior
    • ANS effects
  19. What are some of the functions of septal nuclei?
    • sexual behavior
    • role in developing plasticity (learning and memory)
    • source of cholinergic input to hippocampus
  20. What are some of the functions of the nucleus accumbens?
    • role in addictive behaviors
    • receives (dopaminergic) input from ventral tegmental area (VTA) of midbrain --> "rewards"
  21. Which nucleus appears to connect the lenticular/lentiform nucleus (i.e. putamen and globus pallidus) to the caudate nucleus in certain ventral cross-sections?
    nucleus accumbens

  22. What are 2 effects cocaine and/or methamphetamine have on the dopamine pathway?
    • more dopamine in the synaptic cleft at nucleus accumbens
    • (some addicts) adaptive increases in some DA receptor subtypes (e.g. D3) in nucleus accumbens
    • (tend to normalize in remission)
  23. Which of the following is considered part of both the limbic system and the basal ganglia?

    A. septal nuclei
    B. amygdala
    C. caudate
    D. putamen
    E. nucleus accumbens
    E. nucleus accumbens
    (this multiple choice question has been scrambled)
  24. What are the components and ordering of the "limbic loop"?
    cortex --> basal ganglia --> thalamus --> cortex

    • (basal ganglia nuclei = nucleus accumbens + ventral caudate + ventral putamen)
    • (thalamus nuclei = ventral anterior (VA) nucleus + medial dorsal (MD) nucleus)
    • (input cortex = temporal lobe)
  25. Where is the amygdala?
    • medial temporal lobe (not part of cortex --> collection of nuclei; not layered)
    • deep to uncus
    • immediately anterior to inferior horn of lateral ventricle
    • antero-medial to hippocampus
    • inferior to anterior commissure
  26. What are some inputs and outputs of the nuclei within the amygdala?
    • corticomedial: olfactory input; hypothalamus (feeding centers) output
    • central nucleus: cognitive events or emotional signals from ANS input; hypothalamus and brainstem output
    • basolateral nucleus: cortex input; hypothalamus and brainstem output
  27. What are the inputs and outputs of the amygdala?
    • inputs: highly processed
    • -sensory
    • -prefrontal cortex
    • -hippocampus
    • -brainstem
    • -all cortex areas
    • -visceral afferents (hypothalamus and brainstem)
    • -olfactory stria (olfactory input)

    • outputs: widespread
    • -cortex
    • -hippocampus
    • -hypothalamus
    • -brainstem
  28. What is the function of the amygdala?
    • responsible for learning and maintenance of link between a stimulus and its emotional value
    • stimulation --> fear, anxiety
    • if lesioned --> Kluver-Bucy syndrome
    • orchestrates emotional and drive-related behavior through connections with brainstem, hypothalamus, and cord
  29. If the amygdala is lesioned unilaterally, will the subject be able to undergo aversive conditioning?
    No, there must be bilateral lesioning of the amygdala in order for aversive conditioning to be disrupted. A subject may undergo aversive conditioning if only one amygdala region is lesioned.
  30. Which of the following is NOT an effect of bilateral amygdala damage?

    A. Kluver-Bucy syndrome
    B. can retain old memories but cannot form new ones
    C. inability to recognize fearful facial expressions
    D. inability to undergo aversive conditioning
    B. can retain old memories but cannot form new ones
    (this multiple choice question has been scrambled)
  31. Where is the hippocampus?
    • medial temporal lobe (part of cortex --> layered arrangement)
    • deep to parahippocampal gyrus
    • postero-lateral to amydala
    • medial to inferior horn of lateral ventricle
  32. What is this structure and what are its main components?
    • structure = hippocampus (i.e. hippocampus proper + dentate gyrus)
    • EC (entorhinal cortex)
    • Sub (subiculum)
    • CA1 (cornu Ammon 1)
    • CA2
    • CA3
  33. What is the function of the entorhinal cortex of the hippocampus?
    EC (entorhinal cortex): funnels input from all sensory cortices to hippocampus
  34. What is the function of the hippocampus?
    • role in long term potentiation (LTP): perforant path
    • learning and declarative memory (memory for facts, places, faces, etc.)
    • Hippocampal cells produce BDNF (brain-derived neurotrophic factor) that has some protective function (e.g. against cortisol) but defense is overwhelmed in chronic stress
    • involved in "place" memory
    • involved in navigation (especially right hippocampus)
    • new neurons are born in adult hippocampus
  35. Match each of the following types of memory (letter) with their associated cortical input/output (number).

    A) Declarative
    B) Procedural
    C) Emotional

    1. striatum (basal ganglia); cerebellum
    2. amygdala; limbic system
    3. hippocampus; parahippocampal region
    • A:3
    • B:1
    • C:2
  36. What are the effects of bilateral hippocampus removal, as seen in the famous patient HM?
    • inability to lay down (i.e. consolidate) new declarative memories
    • old memories intact (probably cortex related)
    • no change in intellect/IQ
    • no problems with procedural memory
    • (dysfunctional navigation/"place" memory)
  37. What is long term potentiation (LTP) and what cortical structure is often associated with it?
    • LTP is the molecular process which strengthens groups of synapses that are repeatedly used.
    • LTP is associated with the hippocampus (perforant pathway)
  38. What structure is this? What pathway do the lines represent? What part of the pathway does each line refer to? What mental process is this pathway associated with?

    • structure: hippocampus with dentate nucleus
    • lines represent: perforant pathway
    • (1)yellow line: entorhinal cortex to dentate nucleus
    • (2)pink line: dentate nucleus to CA3
    • (3)purple line: CA3 to CA1
    • (4)green line: CA1 to subiculum
    • (5)red line: subiculum back to entorhinal cortex

    the perforant pathway is associated with Long Term Potentiation (LTP)
  39. What is the "basic limbic circuit"?


    • -Basic limbic circuit is a loop involving 4 structures mainly
    • -2-way connections, except hypothalamus to thalamus
    • -Output to body via hypothalamus, for ANS control
    • -Can get somatic actions thru projections to cortex
    • -As an aside—can think of septal nuc and hypothal as siamese twins when it comes to connections—basically same for each.
  40. What is the "hippocampal circuit" (i.e. Papez circuit)?


    Consider hippo circuit—output via fornix to hypothal, specifically mamm—remember we said mam involved in memory—then info relayed to ant nuc of thal by mamm-thalam tract, thence to cing cortex and through entorhinal back to hippo. Also, intimate connections between hippo and amygdala—allowing for influence of emotions on learning—This is papez circuit—he got circuit right but messed up on function—not really emotion/but laying down of new declarative memories.
  41. What is the function of the stria terminalis? Where are its origin and termination?
    • The function of the stria terminalis is to transmit signals from the amygdala to the septal nuclei, hypothalamic, and thalamic areas of brain (and vice versa).
    • origin: corticomedial division in amygdala
    • termination: ventral medial nucleus of thalamus
  42. What is the "amygdala circuit"?


    REMEMBER THERE are strong connections between amygdala and hippocampus—learning is often easier if there is some emotional content/context...
  43. Where are the septal nuclei located?
    • both sides of the midline where the septum pellucidum extends ventrally to the anterior commissure
    • neurons blend imperceptibally with frontal cortex (region of subcallosal gyrus)
    • anterior to hypothalamus
  44. What are some examples of what you would expect to change in a lab rat that suffers damage to the septal nuclei?
    • increased rage
    • foraging behavior
    • alterations in sexual behavior
  45. Which statement is false?

    A. like the hippocampus, the amygdala and septal nuclei are considered part of the cerebral cortex
    B. the septal nuclei are highly interconnected with the hypothalamus
    C. the amygdala is strongly connected with visceral afferents from the brainstem
    D. the amygdala is highly interconnected with the hypothalamus via the stria terminalis and the VAF (ventral amygdalofugal pathway)
    E. the amygdala is highly interconnected with the hippocampus and hypothalamus (esp. the non-mammillary nuclei)
    A. like the hippocampus, the amygdala and septal nuclei are considered part of the cerebral cortex
    (this multiple choice question has been scrambled)
  46. Is the amygdala inolved in eating behaviors? If so, how?
    Yes, the amygdala receives input from the olfactory system and then transmits this information as an output signal to the feeding/eating centers in the hypothalamic nuclei
  47. The fornix forms the anterior wall of which cranial structure?
    interventricular foramen
  48. What feelings are generated when the amygdala is stimulated?
    • fear
    • anxiety
    • (sometimes rage)
    • deja vu
  49. What is the major input source of information to the hippocampus? What is its major output route?
    • input: enterorhinal cortex (EC): receives sensory info from association cortex
    • output: enterorhinal cortex (EC): delivers info to hypothalamus
  50. What is the cause of an uncal herniation?
    Normally the parahippocampal gyrus rests on thetentorium (not shown here), but when thereis an expanding lesion (such as hemorrhage) in the forebrain, the parahippocampal gyrus is “pushed” over the incisura, the free, stiff edge of the tentorial dura that partially encloses the midbrain. This is called an uncal herniation. The blood supply to the midbrain is compromised, resulting in coma or death.
  51. True or False: The hippocampus is often suspected as the epileptogenic foci (i.e. origin of abnormal electrical activity) in the brain.
    True
  52. Which structure is NOT involved in consolidating a new declarative memory?

    A. hippocampus
    B. septal nuclei
    C. dentate gyrus
    D. neocortex
    E. entorhinal cortex
    B. septal nuclei
    (this multiple choice question has been scrambled)
  53. Where are the "place" cells, which aid in navigation and place recognition, located in the hippocampus?

    A. subiculum
    B. dentate gyrus
    C. CA1 (aka Sommer's sector)
    D. CA2
    E. CA3
    C. CA1 (aka Sommer's sector)
    (this multiple choice question has been scrambled)
  54. Would the dentate gyrus be more articulated and easier to identify in the rostral or caudal portion of the hippocampus?
    rostral hippocampus
  55. What cerebral arteries are associated with the hippocampus?
    posterior cerebral artery
  56. What is the 1 main input into the limbic system and what is its 2 major outputs?
    • input: cerebral cortex
    • outputs: cerebral cortex; hypothalamus

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