DSA: Limbic System

Question 1

What type of information does the thalamic. Nuclei relay and where does it receive inputs from?

Answer 1

Relays general and special sensory info

Receives inputs from cerebellum and basal ganglia

Question 2

What is the function of the ventral anterior and lateral nuclear groups of thalamic nuclei?

Answer 2

Motor information

Question 3

What is the function of the VPM/VPL nuclear group of thalamic nuclei?

Answer 3

Spinothalamic tracts and medial lemniscus, trigeminothalamic tracts

Question 4

What is the function of the MGN?

Answer 4

Receives auditory afferents

Question 5

What is the function of the anterior and medial nuclear groups and intralaminar groups of thalamic nuclei?

Answer 5

Instinctive drives, mood and emotional behavior

Question 6

Where. Are reticular nuclei located?

Answer 6

At midbrain, pons and medullary levels

Question 7

What does the reticularactivating system control and what is it interconnected with?

Answer 7

Controls states of consciousness, sleep, REM, HR and respiration

Interconnected with basal nuclei and motor centers in the brainstem

Question 8

Where do descending reticulospinal tracts originate from and what do they influence?

Answer 8

Originate from medullary and pontine RAS

Influence muscle tone and posture

Question 9

What functions is the hypothalamus involved in?

Answer 9

Control of visceral functions and emotional behavior

Question 10

What is the preoptic area of the hypothalamus?

Answer 10

Transition region that extends rostrally, forms a continuation with basal forebrain

Composed of medial and lateral preoptic nucleus -> medial preoptic nucleus contains neurons that make GnRH

Question 11

What is the periventricuar zone of the hypothalamus?

Answer 11

Adjacent to the 3rd ventricle, synthesizes releasing hormones, projects via hypophyseal portal system to anterior pituitary

Question 12

What is the medial zone of the hypothalamus?

Answer 12

Cell-rich region composed of many nuclei -> supraoptic (chiasmatic) region, tuberal region, mamillary region

Question 13

What is the lateral zone of the hypothalamus?

Answer 13

Contains the medial forebrain bundle -> interconnects the lateral zone with the septal nuclei and the brainstem reticular formation

Lateral hypothalamic nucleus is a large cell group that constitutes the feeding center

Question 14

What is the biggest input into the hypothalamus and where does it arise from?

Answer 14

Fornix; arises from neurons in the subiculum and hippocampus

Divided into precommissura bundle (hippocampus) and large postcommissural bundle (subiculum)

Question 15

What is the medial forebrain bundle of the hypothalamus?

Answer 15

Contains fibers that course rostral caudally thorugh the lateral hypothalamic zone -> ascending and descending fibers that interconnect the septal nuclei, hypothalamus and midbrain tegmentum

Question 16

What is Korsakoff’s syndrome?

Answer 16

Progressive degeneration of the mammillary bodies, hippocampal complex and dorsomedial thalamic nucleus -> impedes the retention of newly acquired memory and no consolidation of short term memory to long term memory

Question 17

What are the symptoms of Korsakoff’s syndrome?

Answer 17

Pts typically have severe difficulties learning new tasks and transforming into long term memory

Difficulty in understanding written material and conducting meaningful conversations

Pts wil confabulate, combine fragmented memories into a synthesized memory of an event that never occurred

Question 18

What is Korsakoff’s syndrome caused by?

Answer 18

A thiamine deficiency, typically associated with chronic alcoholism

Question 19

What are the inputs into the limbic system?

Answer 19

Directly to the amygdala

Indirectly to the hippocampal formation, via entorhinal area

Question 20

What functions is the amygdala vital to?

Answer 20

The motivational and emotional connotations of experience

Question 21

Where is the amygdala located?

Answer 21

Near the temporal pole, between the inf horn of the lateral ventricle and lentiform complex

Question 22

The amygdala receives afferents from where?

Answer 22

Inferior temporal association cortex, the thalamus, septum and olfactory tract

Question 23

What is the primary efferent pathway from the amygdala?

Answer 23

Ventral amygdalofugal pathway

Question 24

What is the function of the septal region of the brain?

Answer 24

THought to function in contro of rage behavior

Question 25

The medial forebrain bundle is the major conduit for what?

Answer 25

Septal nuclei and hypothalamus communication with the brainstem

Question 26

What fibers are found in the medial forebrain bundle and what is thought to be their function?

Answer 26

Dopamine-containing fibers in this area thought to be related to perceptions of pleasure or drive reduction

Question 27

What does the nucleus accumbens play an important roe in?

Answer 27

Behaviors related to addiction and chronic pain

Question 28

Where does the nucleus accumbens receive inputs from?

Answer 28

The amygdaloid complex, hippocampal formation and amygdaofugal fibers traversing the stria terminalis

Question 29

Where do the efferent fibers of the nucleus accumbens project to?

Answer 29

Hypothalamus, nuclei of the brainstem and the globus pallidus

Question 30

What is the hippocampal formation composed of?

Answer 30

Subiculum hippocampus (hippocampus proper) and dentate gyrus

Question 31

What is the subiculum of the hippocampal formation?

Answer 31

Transitional area between the 3 layered hippocampus and 5 ayered entorhinal cortex (parahippocampal gyrus)

Question 32

The dentate gyrus and the hippocampus are each composed of 3 layers. What are they?

Answer 32

External layer = molecular Ayer -> contains afferent axons and dendrites of cells intrinsic to each structure Middle layer = granule cell layer (dentate gyrus) and pyramida layer (hippocampus) -> Dendrites of both cell types radiate into the molecular layer Inner layer = poymorphic layer ->. Contains the axons of pyramidal and granule cells, a few intrinsic neurons and many glia; also contains the elaborate dendrites of neurons in the pyramidal layer, double pyramidal cells

Question 33

What does the innermost part of the hippocampus consist of?

Answer 33

Myelinated axons from cell bodies in subiculum and hippocampus, alveus -> continuous with fimbria -> will become the fornix

Question 34

The fornix will convey projections where?

Answer 34

To the hippocampal formation and entorhinal cortex

Question 35

What is the major input for hippocampal afferents?

Answer 35

Cells of the entorhinal cortex via the perforant pathway - most terminate in the molecular layer of the dentate gyrus and a few in the subiculum and hippocampus

Question 36

Granule cells in the dentate gyrus project to the molecular layer of the ________ region of the hippocampus, which projects to _______ of the hippocampus which then projects to the subiculum

Answer 36

CA3; CA1

Question 37

Where does the subiculum receive projections from?

Answer 37

Amygdaloid complex

Question 38

Where do hippocampal efferents primarily originate from?

Answer 38

Cells of the subiculum and pyramidal cells ofthe hippocampus -> axons of these neurons enter the alveus, coalesce to form the fimbria and then continue as the fornix

Question 39

What s the major output of the hippocampus?

Answer 39

Fornix -> does extend some fibers across the midline in the hippocampal decussation

Question 40

Fibers originating in the subiculum mainly form the _________________ and terminate in the __________________

Answer 40

Postcommissural fornix; medial mammillary nucleus

Question 41

The precommissural fornix is composed of fibers primarily arising from where?

Answer 41

The hippocampus - distribute to the septal nuclei, medial areas of the frontal cortex, the preoptic and anterior nuclei of the hypothalamus and nucleus accumbens

Question 42

Emotion is mediated thorugh the _______________, is controlled and modulated by fibers from the _________

Answer 42

Hypothalamus; fornix

Question 43

Cortical control of emotional activity can be viewed as a pathway originating from the _______________ gyrus, the Papez circuit

Answer 43

Cingulate gyrus

Question 44

The initia segment of the paper circuit is from the _____________ to the _________________

Answer 44

Subiculum to the medial mammillary nucleus (postcommissural fornix)

Question 45

The circuit of Papez is competed by what 3 connections?

Answer 45

1. Mamillothalamic tract that connects the medial mammillary nucleus to the anterior nucleus of the thalamus 2. Thalamocortical fibers from the anterior nucleus to cortex of the cingulate gyrus 3. Projection from the cingulate cortex (via cingulum) to entorhinal cortex, subiculum and hippocampus **The subiculum (via fornix) returns info to the mammillary body

Question 46

What is hippocampal amnesia?

Answer 46

Bilateral lesions of the hippocampi causing profound deficits in anterograde episodic memory (cant learn new material), combined with spared procedural and working memory Pts IQ and formal reasoning were fairly normal

Question 47

The _____________ gyrus and _________________ gyrus are continuous around the specimens of the corpus callosum

Answer 47

Cingulate gyrus & parahippocampal gyrus

Question 48

What is Kluver-Bucy syndrome?

Answer 48

Bilateral temporal lobe lesions that abolish amygdaloid complex resulting in behavioral changes

Question 49

What are the symptoms/behavioral changes seen in pts with Kluver-Buck syndrome?

Answer 49

Visual agnosia (inability to recognize an object by sight) Hyperorality (tendency to examine objects by mouth) Hypermetamorphosis (compulsion to intensively explore the immediate environment or overreact to visual stimuli) Placidity (doesnt show fear or anger like normal) Hyperplagia (eating excessive amts of food when not hungry) Hyper sexuality