Forebrain Anatomy & Limbic System

Question 1

What structures make up the diencephalon?

Answer 1

thalamus, hypothalamus, epithalamus, subthalamus

Question 2

What makes up the epithalamus?

Answer 2

pineal gland

habenula

Question 3

What is (are) the thalamic nuclei of the anterior division of the thalamus?

Answer 3

anterior nucleus (AN)

Question 4

What is (are) the thalamic nuclei of the medial division?

Answer 4

dorsomedial (DM) or medial dorsal (MD)

Question 5

What is (are) the nuclei of the lateral division of the thalamus?

Answer 5

dorsal tier: lateral dorsal (LD), lateral posterior (LP), pulvinar
ventral tier: ventral anterior (VA) ventral lateral (VL), ventral posterior lateral (VPL) and medial and lateral geniculates (MGN, LGN)

Question 6

What are the different division of the thalamic nuclei?

Answer 6

anterior division
medial division
lateral division
intralaminar
reticular nucleus
midline nuclei

Question 7

What defines the subdivisions of the thalamic nuclei?

Answer 7

internal medullary lamina

Question 8

What is the biggest subdivision of the thalamus?

Answer 8

lateral division

Question 9

What is the function of relay nuclei?

Answer 9

receive well-defined specific input from a subcortical source (i.e. medial lemniscus) and project to a well-defined area of cortex (i.e. somatosensory cortex)

Question 10

What is the function of association nuclei?

Answer 10

receive specific inputs from association cortex (i.e. prefrontal cortex) and project back

Question 11

What is the function of intralaminar and midline nuclei?

Answer 11

receive distinct set of specific inputs (basal ganglia, limbic structures)
project to cortex, basal ganglia and limbic structures

Question 12

What is the function of the reticular nucleus?

Answer 12

important source of regulatory input to thalamus
no projection to cortex
input: cortex & thalamus
output: inhibitory axons to thalamus
the nucleus is a sheet of neurons, covers thalamus, axons must traverse nucleus to enter/leave thalamus and send collaterals to it

Question 13

What is the function of the medial geniculate nucleus?

Answer 13

relay nucleus for hearing

Question 14

What is the function of the lateral geniculate nucleus?

Answer 14

relay nucleus for vision

Question 15

What is the function of the ventral posterior medial nucleus?

Answer 15

sensory relay for nucleus of the face

Question 16

What is the function of the ventral posterior lateral nucleus?

Answer 16

sensory relay for nucleus of the body

Question 17

What is the function of the ventral anterior nucleus?

Answer 17

motor relay nucleus

Question 18

What is the function of the ventral lateral nucleus?

Answer 18

motor relay nucleus

Question 19

What is the function of the anterior nucleus?

Answer 19

relay nucleus for the limbic system

Question 20

What is the function of the intralaminar nucleus?

Answer 20

component of the reticular activating system

Question 21

What structures make up the lenticular nucleus?

Answer 21

Globus pallidis

Putamen

Question 22

What are the major inputs to the hypothalamus?

Answer 22

Parts of the forebrain: septal nuclei, 
ventral striatum, 
insula, 
orbitofrontal cortex,
hippocampus, 
amygdala

Brainstem & Spinal Cord:
medial forebrain bundle
dorsal longitudinal fasciculus

Question 23

What are the major hypothalamic outputs?

Answer 23

Many of the same pathways used by inputs

Question 24

What are the inputs to the amygdala?

Answer 24

1. stria terminalis
2. ventral amygdalofugal pathway
3. lateral olfactory tract
4. directly from temporal lobe cortex and hippocampus

Question 25

What are the nuclear groups found within the amygdala?

Answer 25

medial - olfaction central - hypothal, PAG, emotional responses basolateral - cortex, central nuclei, emotional responses

Question 26

What are the three zones of the hippocampus?

Answer 26

dentate gyrus hippocampus proper (cornu ammonis) subiculum

Question 27

What is the function of the pineal gland?

Answer 27

secretes melatonin; regulates sleep-wake cycles, released during darkness

Question 28

Which nuclei are known as relay nuclei?

Answer 28

Sensory: VPL & VPM Motor: VA & VL Limbic: Anterior, LD

Question 29

Which nulcei are known as association nuclei?

Answer 29

DM & Pulvinar Prefrontal: DM (foresight, affect) Parietal-occipital-temporal: Pulvinar-LP complex (function largely unkown, possibly visual perception or attention)

Question 30

almost all fibers going to and from the cortex pass through what structure?

Answer 30

internal capsule

Question 31

What are the five parts of the internal capsule?

Answer 31

anterior limb: lenticular nucleus, caudate posterior limb: lenticular nucleus, thalamus genu: between A & P limbs retrolenticular: behind lenticular nucleus sublenticular part: beneath lenticular nucleus

Question 32

What is the function of the limbic system?

Answer 32

to generate feelings/emotions from sensory inputs, evolved to promote survival

Question 33

What structures make up the limbic system?

Answer 33

cingulate gyrus parahippocampal gyrus amygdala hippocampus

Question 34

What is the function of the thalamus & cortex input on the amygdala?

Answer 34

informs about situations or objects in the environment

Question 35

What is the function of the hypothalamus & limbic system input on the amygdala?

Answer 35

informs about current physiologic and emotional state

Question 36

What is visual agnosia?

Answer 36

failing to recognize what an object is (even though sight is in tact); damage to visual association cortex

Question 37

What tracts do the hypothalamic inputs use?

Answer 37

medial forebrain bundle (spinal cord/brainstem) stria terminalis ventral amygdalofugal pathway dorsal longitudinal fasciculus (spinal cord/brainstem) spinothalamic tract collaterals (spinal cord/brainstem)

Question 38

T/F: hypothalamic cortical outputs end diffusely.

Answer 38

True

Question 39

What is the function of the three different nuclei found in the amygdala?

Answer 39

medial: olfaction central - hypothalamic, PAG: emotional responses basolateral-cortex: central nuclei, emotional responses

Question 40

What characteristics did HM exhibit?

Answer 40

could not form new episodic memories (personal experiences) could not form semantic memories (ideas & concepts not related to personal experiences - facts) He did have working memory and was able to learn new skills (could learn how to solve a puzzle more quickly)

Question 41

What are the three distinct zones of the hippocampus?

Answer 41

1. dentate gyrus 2. hippocampus proper (cornu ammonis) 3. subiculum, transition between hippocampus proper and adjacent parahippocampal cortex

Question 42

What is the hippocampus output-input pathway?

Answer 42

1. afferent fibers from sensory cortex 2. entorhinal cortex projects to dentate gyrus (perforant pathway) 3. dentate neuron projects to CA3 4. CA3 neuron projects into fimbria & CA1 5. CA1 neuron projects to subiculum 6. subiculum projects to fimbria (alvear pathway) 7. subicular neuron projects to entorhinal cortex 8. entorhinal neuron projects to sensory cortex

Question 43

What is the Papez circuit?

Answer 43

interactions among limbic structures, cortex & hypothalamus | Papez proposed that emotional experiences were processed