Limbic System

Front 1

What are the 4 basic function categories of the limbic system?

Back 1

1. Homeostatic functions including autonomic and neuroendocrine control
2. Olfaction
3. Memory
4. Emotions and drives

(HOME)

Front 2

What are the main structures of the limbic system?

Back 2

1. Limbic cortex
2. Hippocampal formation
3. Amygdala
4. Olfactory cortex
5. Diencephalon
6. Basal ganglia
7. Basal forebrain
8. Septal nuclei
9. Brainstem

Front 3

What structures of the LIMBIC CORTEX are involved in the limbic system?

Back 3

1. Parahippocampal gyrus
2. Cingulate gyrus
3. Medial orbitofrontal cortex
4. Temporal pole
5. Anterior insula

Front 4

What structures of the HIPPOCAMPAL FORMATION are involved in the limbic system?

Back 4

1. Dentate gyrus
2. Hippocampus
3. Subiculum

Front 5

What structures of the DIENCEPHALON are involved in the limbic system?

Back 5

1. Hypothalamus
2. Thalamus
a. Anterior nucleus
b. Mediodorsal nucleus
c. Internal medullary
lamina
3. Habenula

Front 6

What structures of the BASAL GANGLIA are involved in the limbic system?

Back 6

1. Ventral striatum
a. Nucleus accumens
b. Ventral caudate and
putamen
2. Ventral pallidum

Front 7

From a simplistic standpoint, what are the 4 structures responsible for each of the 4 main functional categories of the limbic system?

Back 7

1. Homeostasis - Hypothalamus
2. Olfaction - Olfactory cortex
3. Memory - Hippocampal formation
4. Emotions and drive - Amygdala

Front 8

Collateral sulcus

Back 8

Separates the parahippocampal gyrus from the rest of the temporal lobe

Front 9

Rhinal sulcus

Back 9

The anterior continuation of the collateral sulcus

Front 10

Uncus

Back 10

A bump visible on the anterior medial parahippocampal gyrus

Front 11

Isthmus

Back 11

Where the cingulate gyrus joins the parahippocampal gyrus posteriorly

Front 12

What are the 3 main nuclei of the amygdala?

Back 12

1. Corticomedial
2. Basolateral
3. Central nuclei

Front 13

How is the BASAL GANGLIA involved in the limbic system?

Back 13

Limbic inputs to the basal ganglia arrive at the a) VENTRAL STRIATUM and b) NUCLEUS ACCUMBENS - info. is then relayed via the VENTRAL PALLIDUM to the mediodorsal nucleus of the thalamus

Front 14

How is the MEDIODORSAL NUCLEUS of the thalamus involved in the limbic system?

Back 14

It projects limbic info. to the orbitofrontal and anterior cingulate limbic cortices.

Front 15

How many layers does the hippocampal formation have?

Back 15

3

Front 16

Allocortex

Back 16

- "other cortex"
- phylogenetically ancient forms of cortex that do not have 6 distinct layers

Front 17

What are the 2 subcategories of allocortex?

Back 17

1) Archicortex - "first" or "original cortex"

2) Paleocortex - "old cortex"

Front 18

Where is the archicortex?

Back 18

Hippocampal formation

Front 19

Where is the paleocortex predominantly found?

Back 19

In the periform cortex of the olfactory area

Front 20

What is the MESOCORTEX?

Back 20

The regions between 3- and 6-layered cortex, which forms a transitional cortex
- aka "middle cortex"

Front 21

Where is the mesocortex?

Back 21

In the limbic cortex of the parahippocampal gyrus and anterior inferior insula

Front 22

What does the term CORTICOID AREAS mean?

Back 22

Refers to regions of the simple cortex that overlie or merge with subcortical nuclei

Front 23

What are examples of CORTICOID areas?

Back 23

1. Amygdala
2. Substantia innominata
3. Septal region

Front 24

Where is the AMYGDALA?

Back 24

- It lies in the anteromedial TL.
- It overlaps the anterior end of the hippocampus
- It lies ventral to the tip of the temporal horn of the lateral vetricle

Front 25

Where is the BASAL FOREBRAIN?

Back 25

Just anterior and lateral to the hypothalamus, at the base of the frontal lobes near the midline.

Front 26

What is the SUBSTANTIA INNOMINATA?

Back 26

1. The entire basal forebrain or
2. A nucleus within the basal forebrain called the NUCLEUS BASALIS OF MEYNERT, which lies just vetral to the anterior commisure (see p. 767)

Front 27

What does the NUCLEUS BASALIS do?

Back 27

It contaqins cholinergic neurons that provide the major cholinergic innervation fo rthe entire cerebral cortex (see p. 594).

Front 28

What are the primary nuclei of the BASAL FOREBRAIN?

Back 28

1. Nucleus basalis
2. Olfactory tubercle
3. Ventral pallidum
4. Nucleus of the diagnoal band of Broca
5. Preoptic area

Front 29

Where is the SEPTAL REGION?

Back 29

Just dorsal to the basal forebrain, nhear the septum pellucidum

Front 30

What are the main nuclei of the SEPTAL REGION?

Back 30

1. Medial septal nucleus
2. Lateral septal nucleus

Front 31

What does the MEDIAL SEPTAL NUCLEUS do?

Back 31

It contains cholinergic neurons that PROJECT TO the hippocampal formation and may play a role in modulation of memory function.

Front 32

What does the LATERAL SEPTAL NUCLEUS do?

Back 32

1. It RECEIVES info. from the hippocampal formation
2. It has a large PROJECTION TO the medial septal nucleus completing the circuit.

Front 33

What is the MEDIAL OLFACTORY STRIA?

Back 33

It is part of the feedback loop of the anterior olfactory nucleus, which feeds info to both ipsilateral and contralateral olfactory bulbs.

Front 34

What does atrophy of the anterior olfactory nucleus do?

Back 34

- Impaired olfaction
- Seen in Alzheimer's

Front 35

What is the LATERAL OLFACTORY STRIA?

Back 35

It is the tract through with mitral and tufted cells of the olfactory bulb project directly to the primary olfactory cortex.

Front 36

What two cortices make up the PRIMARY OLFACTORY CORTEX?

Back 36

1. Piriform cortex
2. Periamygdaloid cortex

Front 37

Where is the PRIMARY OLFACTORY CORTEX located?

Back 37

Near the medial anterior tip of the TL

Front 38

Besides the primary olfactory cortex, where do fibers of the olfactory tract project to?

Back 38

1. The CORTICOMEDIAL NUCLEUS of the amygdala
2. OLFACTORY TUBERCLE located in the anterior perforated substance

Front 39

Where does the PERIFORM CORTEX send information to?

Back 39

1. Anterior entorhinal cortex (which plays a role in memory and may explain why smells can elicit vivid memories)
2. Orbitofrontal olfactory area - both directly and indirectly thru the entorhinal cortex or the mediodorsal nucleus of the thalamus
3. Basolateral amygdala
4. Lateral preoptic area
5. Nucleus of the diagonal band

Front 40

What 3 main regions of the brain appear to be critical to memory formation, consolidation, and retrieval?

Back 40

1. Medioal temporal lobe memory areas
2. Medial diencephalic memory areas
3. The white matter network connections between 1 & 2

Front 41

What structures are involved in the MEDIAL TEMPORAL LOBE memory areas?

Back 41

1. Hippocampal formation
2. Parahippocampal gyrus

Front 42

What structures are involved in the MEDIAL DIENCEPHALIC memory areas?

Back 42

1. Thalamic nuclei
a. Mediodorsal nucleus
b. Anterior nucleus
c. Internal medullary lamina
2. Mammillary bodies
3. Other diencephalic nuclei lining the 3rd vetnricle.

Front 43

What are the 3 components of the HIPPOCAMPAL FORMATION?

Back 43

1. Dentate gyrus
2. Hippocampus
3. Subiculum

Front 44

What cortical areas are included in the parahippocampla gyrus?

Back 44

1. Entorhinal cortex (anterior portion)
2. Parahippocampal cortex (posterior portion)
3. Perirhinal cortex (medial and lateral walls of the rhinal sulcus)

Front 45

What does the entorhinal cortex do?

Back 45

It serves as the major input and output relay between association cortex and the hippocampal formation.

Front 46

Where does the main input to the hippocampal formation arrive from?

Back 46

From the association cortex in the F, P-O, and T lobes, through the entorhinal cortex.

Front 47

Where does association info go to before going to the entorhinal cortex?

Back 47

To the perirhinal cortex and parahippocampal cortex (see p. 773 & 776)

Front 48

Where is memory storage thought to take place?

Back 48

In the association and primary cortices that allow a particular memory to be reactivated.

Front 49

What are the important output pathways of the hippocampal formation?

Back 49

1. The projection from the subiculum to the ENTORHINAL cortex and from there back to multimodal association cortex.

2. From the subiculum to the FORNIX, which carries outputs to the diencephalon and septal nuclei.

Front 50

What structure allows communication between the hippocampi?

Back 50

Hippocampal commissure (see p. 778)

Front 51

How do the medial septal nucleus and the nucleus of the diagonal band influence the hippocampal formation?

Back 51

They provide modulatory inputs via the fornix, arising from their cholinergic inputs.

Front 52

What is the alveus?

Back 52

A white matter layer on the ventricular surface of the hippocampus.

These are output fibers from the hippocampal formation. (see p. 774 & 778)

Front 53

What are the 3 main targets of axons traveling forward in the fornix?

Back 53

1. Medial and lateral mammillary nuclei
2. Lateral septal nucleus
3. Anterior thalamic nucleus

Front 54

What is the Papez circuit?

Back 54

A complete loop of structures in the limbic system.