Limbic System

Front 1

Limbic System Overview

Back 1

- expresses behavioural & emotional expression by way of the hypothalamus & the ANS

Front 2

Major Components & Connections

Back 2

1. Orbitofrontal cortex
2. Mediodorsal nucleus of the thalamus
3. Anterior nucleus of the thalamus
4. Septal area
5. Limbic Lobe
6. Hippocampal formation
7. Amygdaloid complex
8. Hypothalamus
9. Limbic midbrain nuclei

Front 3

Orbitofrontal cortex

Back 3

F: conscious perception of smell
- reciprocal connections with mediodorsal thalamus
- interconnected through medial forebrain bundle with septal area & hypothalamic nuclei

Front 4

Mediodorsal nucleus of thalamus

Back 4

- input from mamillary nucleus through amillothalamic tract & fornix
- projects to cingulate gyrus & a major link in Papez Circuit

Front 5

Septal Area

Back 5

- telencephalic structure
- reciprocal connections with the hipocampal formation through fornix & with hypothalamus through medial forebrain bundle
- projects through stria medullaris to the habenular nucleus

Front 6

Limbic Lobe

Back 6

- includes suncallosal area, paraterminal gyrus, cingulate gyrus & isthmus & parahippocampal gyrus which includes the uncus
- also contains hippocampal formation & amygldala

Front 7

Hippocampal formation

Back 7

sheet of archicortex that is jelly-rolled into parahippocamplal gyrus
- F; learing, memory & recognition of novelty
INPUTS: entorhinal cortex
OUTPUTS; fornix

1. denatate gyrus; recieve hippocampal input and projects to pyramidal cells of hippocampus & subiculum
2. Hippocampus; pyramidal cells that project through fornix to sepatal area & hypothalamus
3. Subiculum: input through hippocampal pyramidal cells, projects through fornix to mamillary nuclei & anterior nucleus of the thalamus

Front 8

Amygdala

Back 8

basal gagnlion underlies parahippocamapal uncus.
- stimulaion causes fear & signs of SNS overactivity
- lesions can cause placidity & hypersexual behaviour
INPUT: sensory assoc. cortex, olfactory bulb & cortex, hypothalamus, sepatal area, hippocampal formation
OUTPUT: stria terminalis to hypothalamus & septal area & to mediodrorsal thalamus

Front 9

Hypothalamus

Back 9

reciprocal connections with amygdala

Front 10

Limbic midbrain nuclei

Back 10

VTA (DA)
Raphe nuclei (5HT)
locus ceruleus (NA)

Front 11

Papez Circuit

Back 11

1. Hippocampal formation to
2. Mammillary nucleus
3. Anterior Thalamus
4. Cingulate Gyrus
5. Enterohinal area
6. Hippocampal formation

Front 12

Kluver-Bucy Syndrome

Back 12

bilateral ablation of anterior temporal lobes including amydala.
- causes psychic blindness, hyperphagia, docility, hypersexuality

Front 13

Amnestic Syndrome

Back 13

bilateral infarction of hippocampal formation
- causes anterograde amnesia, memory loss (hippocampal pathology)

Front 14

Foster Kennedy Syndrome

Back 14

meningioma of lofactory groove, compresses both olfactory and optic nerves thus
- ipsilateral anosmia and optic atrophy & contralateral papilledema (due to INC. ICP)

Front 15

Epilepsy

Back 15

Hippocampus most epileptogenic part of cerebrum

Front 16

Bilateral transection of fornix

Back 16

acute amnestic syndrome

Front 17

Wernickes Encephalopathy

Back 17

due to B1 def.
- TRIAD
1. ocular disturbances & nystagmus
2. gait ataxia
3. mental dysfunction

Front 18

Strachan's Syndrome

Back 18

due to high dose B1
- TRIAD
1. spinal ataxia
2. optic atrophy
3. nerve deafness

Front 19

Bilateral Destruction of cingulate gyri

Back 19

causes loss of initiative and inhibition as well as dulling of the emotions
- memory is unaffected
- lesions cause placidity
- Cingulectomy used to treat sever anxiety & depression