A3-4: Limbic System, Lateralization, Corpus Callosum, Diencephalon

Front 1

Back 1

Front 2

Where in the brain are emotions mainly processed?

Back 2

Limbic system

Front 3

Which structures are most often considered part of the limbic system?

Back 3

- Hippocampus (+ gyrus dentatus, fornix)
- Gyrus parahippocampalis
- Gyrus cinguli
- Corpus amygdaloideum (amygdala)
- Corpus mamillare

Sometimes also:
- Parts of olfactory cortex
- Parts of thalamus
- Indusium griseum

Front 4

Hippocampus: Location, afferences, efferenzes and function.

Back 4

Location: Floor of the cornu temporale of the ventriculus lateralis. Mostly located in lobus temporalis.

Afferences:
- From gyrus parahippocampalis (area entorhinalis).
---- impulses from olfactory cortex, amygdala and neocortex
---- somatosensory, visual, auditory and olfactory info
- Also: thalamus, gyrus cinguli, fornix

Efferences:
- Circle: Run in fornix to the corpora mamillaria -> thalamus (ncl. anterior) -> gyrus cinguli -> back to hippocampus

Function:
- Transfer contents from short term to long term memory
- Endocrine, visceral and emotional processes

Front 5

Fornix: Location, function

Back 5

Location: Crescent-shaped group of fibers running over the roof of the ventriculus tertius. Connects the hippocampus with the corpus mamillare.

Function: Plays important role in learning: Storage of memory contents from STM into LTM.

Front 6

Commisura fornicis

Back 6

The commisure between the fornix on either side. Connects the two hemispheres.

Front 7

Where in the brain are emotions mainly processed?

Back 7

Limbic system

Front 8

Which structures are most often considered part of the limbic system?

Back 8

- Hippocampus (+ gyrus dentatus, fornix)
- Gyrus parahippocampalis
- Gyrus cinguli
- Corpus amygdaloideum (amygdala)
- Corpus mamillare

Sometimes also:
- Parts of olfactory cortex
- Parts of thalamus
- Indusium griseum

Front 9

Hippocampus: Location, afferences, efferenzes and function.

Back 9

Location: Floor of the cornu temporale of the ventriculus lateralis. Mostly located in lobus temporalis.

Afferences:
- From gyrus parahippocampalis (area entorhinalis).
---- impulses from olfactory cortex, amygdala and neocortex
---- somatosensory, visual, auditory and olfactory info
- Also: thalamus, gyrus cinguli, fornix

Efferences:
- Circle: Run in fornix to the corpora mamillaria -> thalamus (ncl. anterior) -> gyrus cinguli -> back to hippocampus

Function:
- Transfer contents from short term to long term memory
- Endocrine, visceral and emotional processes

Front 10

Fornix: Location, function

Back 10

Location: Crescent-shaped group of fibers running over the roof of the ventriculus tertius. Connects the hippocampus with the corpus mamillare.

Function: Plays important role in learning: Storage of memory contents from STM into LTM.

Front 11

Commisura fornicis

Back 11

The commisure between the fornix on either side. Connects the two hemispheres.

Front 12

Back 12

Fornix

Front 13

Back 13

Fornix, sagittal view

Front 14

Back 14

Fornix, coronal view

Front 15

Gyrus cinguli: Location, parts, function

Back 15

Location: Above corpus callosum. Part of the telencephalon. Along with hippocampus largest structure of the limbic system.

Parts:
- Pars posterior (BM 23)
- Pars anterior (BA 24)
- Area subcallosa (BM 25)
- Cingular motor areas (BM 32)

Function:
- Affects vegetative parameters (e.g. nutrition uptake)
- Psychomotor & locomotor drive
> Via connections with other limbic structures, association cortex and striatum
> Controls emotionally triggered facial movements such as laughing and crying

Front 16

Back 16

Front 17

Which functions do the different parts of the limbic system have?

Back 17

Hippocampus: Memory, behavior, emotional & vegetative functions.

Gyrus parahippocampalis: Memory, leading on sensory information to the hippocampus.

Gyrus cinguli: Psycho- & locomotor drive, vegetative modulation.

Corpus amygdaloideum: Affective behavior, affective motivity, emotional learning, affects vegetative functions.

Corpus mamillare: Memory, affective behavior, vegetative functions.

NB! Work together with other regions!

Front 18

Back 18

Front 19

Lateralization

Back 19

Some processes take place mainly in one of the cerebral hemispheres.

LEFT:
- Language: left side dominant in most people (right handers: always left. left handers: can be either)
- Abstract skills (e.g. mathematical operations, word recognition)

RIGHT:
- spatial visualization, memory for faces, musical skills

Front 20

Corpus callosum: function and parts

Back 20

Function: Connects cortical areas (M1, S1, association areas) of the two hemipheres
=> le-ri connection of memories, aquired skills & intellectual efforts

Parts: Rostrum, genu, truncus, splenium.

Front 21

What structure is 1-4?

Back 21

Corpus callosum

Front 22

Callosotomie

Back 22

= split brain: Severing the Corpus callosum.

- No serious loss of aquired skills, memory of intelligence.
- Motor skills can later be learned with each hemisphere separately

- However, still medically verifiable:
>> Optic information can only be reproduced using language (verbally and in writing) when the information is registered by the dominant hemisphere (i.e. coming from the contralateral visual hemifield).
>>> Thus, information from the left visual hemifield, processed in the right hemisphere, can't reach the left-dominant language center!
>>> However, affected persons are able to identify a similar object with the left hand (controlled by the right hemisphere = same side as visual processing of object).

Front 23

What structures surround the diencephalon?

Back 23

WTF? I don't get this one.

Slide: Abgrenzungen
• kaudal, ventral, dorsal: Mesencephalonstrukturen
• Abgrenzung zum Telencephalon wesentlich schwieriger, weil im Laufe der Embryonalentwicklung diese beiden Teile des Neuralrohres paraIell zusammen wachsen: („Vermischungsgebiete“).

Front 24

Back 24

Front 25

Back 25

Front 26

What centers can be found in the diencephalon?

Back 26

Centers for:
- Olfactory pathway
- Visual pathway
- Auditory pathway
- Tactile and proprioceptive information
- Emotions

Front 27

How is the diencephalon subdivided?

Back 27

- Epithalamus
- Thalamus
- Hypothalamus (+pituitary)
- Subthalamus

Front 28

Back 28

Front 29

What structure?

Back 29

Epithalamus

Front 30

Epithalamus: location and parts

Back 30

Location: Dorsal-most part of the diencephalon. Above the thalamus.

Parts:
- Stria medullaris thalami
- Nuclei habenulae
- Corpus pineale (epiphysis/pineal gland)
- Area pretectalis
- Commisura posterior

Front 31

Stria medullaris thalami: structure & function

Back 31

STRUCTURE:
- Narrow bundle of fibers medial to the thalamus (though mostly unrelated)
- Ends dorsally next to the two nuclei habenulares

FUNCTION:
- Passes information (afferences) on to the nuclei habenulares

Front 32

Habenula: structure & function

Back 32

STRUCTURE:
- Two rein-like structures connecting the epiphysis with the thalamus
- Contains the ncll. habenulares

FUNCTION:
- Not clear
- Probably relay station for impulses from the olfactory cortex, passing them on to the brain stem, where they reach vegetative cranial nerve nuclei
= how smell can influence food intake (salivation at pleasantly smelling foods, nausea and disgust at unpleasant smells)

Front 33

Corpus pineale: names, structure, function, malfunction

Back 33

NAMES: Corpus pineale, Zirbeldrüse, Gld. pinealis, Epiphyse.

STRUCTURE:
- Name < shaped like pine cone (though not really...)
- Grey-reddish neuro-endocrine gland, a few mm large
- No direct afferences from the rest of the diencephalon

FUNCTION:
- Specific cells produce the hormone serotonine, which via intermediate steps becomes melatonin.
>> Hormone production controlled by circadian rhythm:
>> Melatonin ("zeitgeber-hormone") mainly produced at night
>> Sleep-wake cycle and other time dependent bodily rhythms are controlled by melatonin
>> Also appears to have inhibitory influence on genital system

MALFUNCTION:
- impaired daily rhythm (SAD, sleep disorders, ++)
- absence or premature appearance of sexual maturity

Front 34

Back 34

Front 35

Area pretectalis: structure, function, afferences, efferences

Back 35

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Front 36

Consensual light response

Back 36

txt

Front 37

Commisura posterior: Location, structure

Back 37

txt

Front 38

Back 38

Front 39

Back 39

Front 40

Back 40

Front 41

Back 41

Front 42

Structure? Function? Associated cortical areas?

Back 42

VNG = ventral nuclear group of thalamus

Front 43

Structure? Function? Associated cortical areas?

Back 43

Anterior-medial-lateral nuclear group
-> limbic system, PFC, parietal cortex

ANTERIOR: Part of limbic thalamus
- learning, memory, emotions

MEDIAL: regulates excitability of forebrain, emotions, cognitive learning, memory

LATERAL: not really a group (= posterior region + VNG)

Front 44

Structure? Function? Associated cortical areas?

Back 44

Dorsal nuclear group
-> visual cortex, auditory cortex, language processing

Front 45

Back 45

Front 46

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Front 47

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Front 48

Back 48

Fornix