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102 Cards in this Set

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  • Back
The limbic system links a group of functionally related structures that are interposed between the _______ & _______.
Cerebral cortex & Diencephalon
The limbic system consists of what structures?
1. Hippocampal formation
2. Septal area
3. Amygdala
4. Prefrontal cortex
5. Cingulate Gyrus
and some authors include the hypothalamus
What is a critical property of the limbic structures?
To modulate the functions normally attributed to the hypothalamus and/or midbrain PAG
Limbic structures receive inputs from at least two sources:
1) ?
2) ?
1. From one or more sensory systems either directly or indirectly thru interneurons in CC

2. From brainstem monoaminergic fiber systems
Limbic neurons project directly or indirectly to the _____ and/or _________
Hypothalamus and/or midbrain PAG
While the hippocampal formation has few if any direct connections with the lateral hypothalamus, it is known to modulate functions associated with the hypothalamus. What structure forms the underlying anatomical synaptic relay subserving regulation of the hypothalamus by the hippocampal formation?
Septal area.

Fibers located in the precommissural fornix supply the septal area in an extensive and topographical manner. In turn, the septal area projects significant numbers of fibers to the lateral and medial regions of the hypothalamus. In this manner, the septal area serves as a relay for the transmission of signals from the hippocampal formation to the hypothalamus.
What constitutes the Papez Circuit?
Hippocampal formation-->mammillary bodies--> anterior thalamic nucleus-->cingulate gyrus-->Entorhinal Cortex/hippocampal formation
A 49-year-old male showed changes in emotional behavior over the past few months. Several characteristics of his behavior included heightened sexuality, a very placid appearance, and making physical contact with almost anything that he could touch. The neurologist's diagnosis was that the patient was exhibiting Kluver-Bucy syndrome. An MRI was given to the patient and a small vascular lesion was detected.

What structure is most likely to contain the lesion?
Amygdala.

In this syndrome, produced experimentally in monkeys and also seen in cats, there is an extreme change in the personality of the animal. Its responses to emotion-laden stimuli are much reduced. It appears very tame. Aggressive tendencies are not evident. It also manifests oral tendencies and displays hypersexuality. This syndrome is the result of lesions of the temporal lobe in which parts of the amygdala are involved.
Which of the following best reflects an anatomical or functional property of the central nucleus of amygdala?

a. Projects its axons to the medial hypothalamus via the stria terminalis
b. Is a major receiving area for info concerning tertiary auditory and visual signals
c. Has high conc. of enkephalins, somatostatin, and dopamine
d. Is a primary location of Norepi-containing cell bodies in the forebrain
e. Projects axons that directly inhibit spinal motor neurons.
C.
Limbic structures send feedback signals to CC, which provide the cortex with _____ signals that are contiguous with other sensory signals that initially caused excitation of limbic nuclei.
Visceral
The contiguity of feedback signals to the CC provide the _____ quality to sensory signals
Emotional
What makes up the hippocampal formation?
1. Dentate gyrus
2. Subicular Cortex
3. Hippocampus
What is the primary cell typ in the hippocampus?
The pyramidal cell, which has both apical and basal dendrites.
What is the course of the basal dendrites of the pyramidal cells of the hippocampus?
The basal dendrites extend laterally & in the direction of the ventricular surface
What is the course of the apical dendrites of the pyramidal cells of the hippocampus?
The apical dendrites extend away from the ventricular surface towards the dentate gyrus
What is the primary efferent process of the hippocampal formation?
Axons of the pyramidal cell
What is the course of the axons of the pyramidal cell of the hippocampal formation?
Axons of the pyramidal cell pass into the superficial layer of the hippocampus called the alveus( a fiber layer adjacent to the inferior horn of the lateral ventricle) & ultimately into either the fibria-fornix or entorhinal cortex
Where is the hippocampal formation?
Occupies the inferomesial portion of the temporal lobe.

Portion of the temporal lobe that is inferior to the temporal horn of the lateral ventricle and medial to the collateral sulcus.
What forms a glistening white cover that carpets the ventricular surface of the hippocampus and extends posteromedialy into the fibria?
Alveus
What are the 4 layers of the hippocampus?
1. External plexiform layer
2. Stratum oriens
3. Pyramidal cell layer
4. Stratum radiatum and lacunosum-moleculare
Which layer of the hippocampus contains axons of pyramidal cells that project outside the hippocampus as well as hippocampal afferent fibers from the entorhinal cortex?
External plexiform layer
Which layer of the hippocampus contains the basal dendrites and basket cells?
Stratum oriens
Which layer of the hippocampus contains the apical dendrites of the pyramidal cells and hippocampal afferents from the entorhinal cortex (perforating pathway)
Stratum radiatum and lacunosum-moleculare
The pyramidal cells of the hippocampus situated closest to the subiculum referred to as the CA___ field
CA 1
The hippocampal field located within the hilus of the dentate gyrus is called CA ___.
CA 4
The collaterals of axons arising from the CA 3 pyramidal cells are called?
Recurrent of Schaffer collaterals
The collaterals of axons arising from the CA 3 pyramidal cells project to_______.
Back to the CA 1 field.
This hippocampal field is highly susceptible to anoxia, especially during periods of the temporal lobe epilepsy.
CA 1 field
Which hippocampal field is referred to as Sommer's sector?
CA 1 field
What is the principle cell type in the dentate gyrus?
Granule Cell
What are the axons of the granule cell called?
Mossy fiber
Mossy fibers (of the dentate gyrus) make synaptic contact with what?
Pyramidal cells in the CA 3 region
A polymorphic cell layer composed of ________ lies deep to the granule cell layer.
Modified pyramidal cells
What lies external to the granule cell layer of the dentate gyrus?
Molecular cell layer
What does the molecular layer of the dentate gyrus consist of mainly?
Axons of hippocampal afferent fibers.
What constitues a transitional region between the entorhinal cortex and hippocampus?
Subicular Cortex
Which is thicker: the pyramidal cell layer in the subicular cortex or the pyramidal cell layer in the hippocampus?
Subicular cortex
What is a major source of inputs to the hippocampus?
Entorhinal cortex
What pathway passes from the lateral entorhinal cortex into the molecular layer of the hippocampus?
Lateral perforant pathway
What structures make up the Papez circuit?
Hippocampal formation
Mammillary body
Anterior Thalamic Nucleus
Cingulate Gyrus
Entorhinal Cortex
What is the name of the pathway to that enters the alveus of the hippocampus after passing thru the white matter of the subiculum?
Medial perforant pathway
The diagonal band of Broca of the septal area supplies what?
Hippocampus
The septal area receives inputs from the hippocampal formation via the ______________.
Precommissural fornix
These projections of the brainstem reticular formation which supply the hippocampus also supply other parts of the limbic system to provide the anatomical & physiological substrates that regulate mood changes.
Monoamine neuronal projections
By receiving inputs from varied sources, the hippocampal formation can respond to sudden changes in brainstem and cortical events and relay such changes to the hypothalamus which then provides a _____ and/or ____quality to these events.
visceral and/or emotional
Efferents from the hippocampus arise from what cell type?
Pyramidal cells located in both the hippocampus & subicular cortex
Axons of what cell type provide the largest component to the fornix?
Pyramidal cell
What are the 3 components of the fornix system?
1. Precommissural fornix
2. Postcommissural fornix
3. Commissural component
This component of the fornix supplies the septal area.
Precommissural fornix
This component of the fornix supplies the diencephalon.
Postcommisural fornix
This component of the fornix supplies the anterior thalamic nucleus.
Postcommissural fornix
This component of the fornix innervates the mammillary bodies.
Postcommissural fornix
The postcommissural fornix arises solely from ____________.
the subicular cortex
Which component of the fornix provides connections between the hippocampus on each side of the brain?
Commissural component
Which component of the fornix may provide the structural basis by which seizures spread from the hippocampus on the other other side?
Commissural component
The hippocampal fibers that provide commissural connections arise mainly from which hippocampal regions?
CA 3 and CA 4
Modulation of aggression, autonomic, and endocrine functions likely result from what?
Direct or indirect hippocampal inputs to different regions of the hypothalamus
What limbic structure modulates aggressive reactions?
Hippocampal formation
Activation of which portion of the hippocampal formation facilitates predatory attack behavior?
The part of the hippocampal formation closest to the amygdala (temporal pole)
Activation of which portion of the hippocampal formation suppresses predatory attack behavior?
The portion of the hippocampal closest to the septal pole
Aggression is mediated to the hypothalamus via interneurons of the _______.
Septal area.
What limbic structure contributes to the regulation of aggressive forms of behavior?
Hippocampal formation
Concentrating neurons of this hormone are densley packed in the ventral region of the hippocampal formation.
Estradiol
This pathway arises from the subiculum and terminates in the region between the suprachiasmatic and arcuate nuclei.
Corticohypothalamic tract
What is a memory disorder in which the patient displays amnesia of both anterograde & retrograde memory?
Korsakoff's syndrome
What syndrome is involved with both heavy alcohol use and a vitamin B deficiency?
Korsakoff's symndrome
What type of amnesia refers to loss of memory that occurs before damage to the hippocampus?
Retrograde memory
What type of amnesia refers to loss of memory that occurs after damage to the hippocampus?
Anterograde memory
After a patient experiences a hippocampal lobectomy, what type of amnesia would be most prevalent?
Anterograde amnesia.

The patient can remember events that took place in the distant past but cannot remember events that occurred recently.
Patient presents with the inability to encode, categorize and abstract relevant info necessary for the learning process. Patient cannot establish new, long-term memories. In which limbic structure do you expect the patient to have a lesion?
Hippocampus
Blocking this receptor in the hippocampus eliminates long term potentiation.
NMDA receptors
What 2 cell groups are associated with the septal area?
1. Bed nucleus of the stria terminalis
2. Nucleus accumbens
What limbic structure serves principally as a relay of the hippocampal formation to the hypothalamus?
Septal Area
Electrical stimulation of the septal area modulates:_____
self-stimulation & drinking behavior
These inputs into the limbic system provide a basis for the regulation of mood states.
Monoaminergic inputs
What nucleus is of interest in the development of Alzheimer's patients?
Basal nucleus of Meynert
Neurofibrillary tangles is a key characteristic of what neurological condition?
Alzheimers
What has been shown to be a risk factor for onset of Alzheimer's disease?
The C4 allele of the spolipoprotein E situated on Chromosome 19. Results in amyloid deposits
This limbic structure contains a cortical mantle called the pyrifom lobe.
Amygdala
What are the 2 functional divisions of the amygdaloid complex?
1. Corticomedial group
2. Basolateral group
The cortex immediately adjacent to the amygdala at rostral levels is referred to as the _____ area.
Prepyriform
Posterior regions of the pyriform lobe are referred to as the ______ cortex.
Periamygdaloid
This limbic structure receives inputs from structures linked with transmission of both olfactory and taste signals.
Amygdala
What are the afferents to the Amygdala?
THE FOLLOWING PROJECT TO THE AMYGDALA:
1. Olfactory bulb
2. Pyriform lobe
3. Solitary Nucleus
4. Temporal neocortex
5. Prefrontal cortex
6. Ventromedial hypothalamus
7. Substantia Innominata
8. Nuclei of the diagonal band of Broca
9. Medial Thalamus
What are the most significant projections of the amygdala?
1. Hypothalamus
2. Bed Nucleus of Stria Terminalis
3. Midbrain PAG
Ventral amygdalofugal pathway arises from the amygdala and supplies what?
The lateral hypothalamus and midbrain PAG
The _____ maintains a significant anatomical relationship with the prefrontal cortex, with which it shares reciprocal connections.
amygdala
Syndrome characterized by:
Hyper-sexuality
A change in dietary habits
Decrease in anxiety toward fear-producing objects,
Tendency to orally explore and contact inedible objects
Visual agnosia
Kluver-Bucy syndrome
Stimulation of which area of the amygdala has a powerful, facilitating effect on defensive rage behavior but has an equally potent suppression on predatory attack behavior?
Corticomedial Amygdala
Stimulation of which area of the amygdala has a powerful, facilitating effect on predatory attack behavior but has a suppression on defensive rage behavior?
Basolateral Amygdala
Medial amygdaloid potentiation of rage behavior is mediated by fibers of the ______ that excite medial hypothalamic neurons and that use______ as a neurotransmitter.
Stria Terminalis;
substance P
The central & lateral amygdaloid suppression of defensive rage behavior is mediated thru an inhibitory enkephalinergic projection to the _____.
Midbrain PAG
Activation of which area of the amygdala facilitates GH release?
Basolateral amygdala
Activation of which area of the amygdala inhibits GH release?
Corticomedial amygdala
Stimulation and lesions suggest that the _____ amygdala has a facilitative effect, while the ____ amygdala is inhibitory.
Basolateral;
Corticomedial
Stimulation of the _____ amygdala induces ovulation.
Corticomedial
Transection of the _____ abolishes ovulation
stria terminalis
Anterior Cingulate Gyrus receives inputs from:
1. Anterior Thalamic Nucleus
2. Dopaminergic fibers from the ventral tegmental area
3. Diagonal band of Broca
ACG projects efferent fibers to:
1. Mediodorsal Thalamic Nucleus
2. Subicular Cortex
Upon lesion/damage of the prefrontal cortex, what characteristics would you expect a patient to exhibit?
Emotional and personality changes;
Irritability;
Irrational & hostile behavior
What technique was used for controlling human violence & manifestations of psychotic behavior? (Technique involved undercutting of the afferent and efferent connections of the prefrontal cortex
Prefrontal Lobotomy
Lesion of the _____ cortex lead to an increase in feeding behavior.
Prefrontal cortex