The Limbic System Flashcards
What is the simple role of the limbic system?
Regulates our emotional and behavioural responses, particularly responses needed for survival
The five F’s of the limbic system: Feeding, fighting, fleeing, feeling and ‘romance’
Give a rough idea of where the limbic system is created.
The initial cortical regions around the brainstem.
Is deep within the brain, above the brainstem and below the cerebral cortex.
What did Charles Darwin note about emotion?
That emotion is similar between different species and humans of different cultures and populations.
This suggests that primary emotion has an evolutionary basis.
What did Paul Broca argue about the limbic system?
Believed the limbic system was mainly olfactory and that our sense of smell had a crucial impact on how we generate and regulate emotions.
The included the oflactory bulb, tract and tubercule in the limbic system.
What is important to note about the location of the olfactory areas of the brain?
Are in close proximity to the amygalda, is likley due to olfactory strong ifluence over primitive emotions is mammalian groups.
What are the different anatomical regions of the olfactory system and what is there function?
The olfactory bulb - deep to the cribiform plate, receptor neurone from the olfactory epithelium synpase with olfactory bulb neurones (formation of the cranial nerve)
The olfactory tract - connects bulb to cortex
The optic tubercule - role in motor guided motivational behaviour
The piriform cortex - processes and codes olfactory information (decides what you are smelling - good/bad)
The entorhinal cortex - links normal odor perception and memory.
What is the role of the optic chiasm?
Allows afferent information from the optic nerve to cross the the contrlateral side.
What is the histological classification of the pyriform cortex (part of the olfactory system)?
Paleocortex
Made of three distinct layers, this is a more ancient style of organisation.
What is the histological classification of the primary motor and visual cortex?
Neocortex
Six histological layers
This is the dominant type of histology associated with higher cognitive function
What is the histological classification of the hippocampus?
The archicortex
What is the role of the hypothalamus?
How does this link to sham rage?
Controls the ANS
Role in emotion
When the hypothalamus is lesioned sham rage occurs.
What is the Papez circuit?
Why is it important in the development of the limbic system?
First person to suggest the limbic system (extras such as hypothalamus alongside the olfactory system) were involved in emotional control based on anatomical circuit tracing and patients with lesions
The papez circuit is:
1. Hippocampus
2. Fornix
3. Mammillary bodies (posterior hypothalamus)
4. Mammillothalamic tract
5. Anterior thalamic nucleus
6. Cingulate cortex
7. Hippocampus
Harry Found Megan, Megan Agitated Catherine Horribly.
What are the different functions of the hypothalamus, hippocampus and the thalamus?
All are componenets of the limbic system
The hypothalamus - regulates the ANS and emotion (causes sham rage)
The hippocampus - also has a role in memory
The thalamus - relays motor and sensory information to cortex
What is the cingulate cortex?
Located just above the corpus callosum.
Part of the limbic system, links emotions, reward and punishment system to behavioural outputs, links limbic system to the rest of the cortex.
What is the corpus callosum?
White matter that links the two cerebral hemispheres of the brain.
What are the different roles of the neocortex, cingulate cortex and the hypothalamus in emotion?
Neocortex - emotional colouring, thoughts and ideas associated with emotion, blue =sad
Cingulate cortex - emotional experience - what we determine the emotion as
Hypothalamus - physical response through the ANS, increase HR etc
Give the basic location of the amygalda.
Is located within the medial temporal lobe, just anterior to the hippocampus.
Bilateral structure.
What is the function of the amygdala?
Is associated with anger, violence, fear and anxiety
What might suppression or removal of the amygdala cause?
Unable to recognise or conceptualise fear
Mellowing on personality.
Kluver-Bucy disease - hyperorality, hypersexuality, disinhibited behaviour, describe as having no fear of consequences.
Describe the location of the hippocampus.
Is located in the medial temporal lobe, just posterior to the amygdala, loops round as the fornix posterior then superior to the thalamus to become the mammillary bodies posterior to the thalamus.
What are the different regions of the hippocampus?
The body and the white matter connection segment called the fornix, this connects to the hypothalamus.
What is the rhinal sulcus?
Contains the entorhinal cortex role in oflactory, memory, navigation and perception of time
Contains the perirhinal cortex role in object recognition
Loacted on parahippocampal gyrus
What gyrus does the hippocampus connect to?
The parahippocampal gyrus
What is important to remember about the ciruitory connections of the hippocampus?
Is very complicated and detailed, has connections to all association areas in the cortex, hence association is dependent on memory.
What is the important ciruitory of the hippocampus in memory formation?
Sensory information from S1 to
Cortical Association Areas to
Parahippocampal and rhinal cortical areas to
Hippocampus
The hippocampus may then realy back to cortical associatoin areas or send information by the fornix to the thalamus and the hypothalamus
What type of memory is the hippocampus associated with?
Is mainly associated with declarative memory, this is the explicit of conscious recollection of facts.
E.g struggle to remember directions or phone numbers.
What might a lesion of the hippocampus result in?
Failure to form new declarative memory. (anterograde amnesia) or recall memories(retrograde amnesia)
What is meant by plasticity in relation to synapses?
The ability to change the location, strength and size of synapses. Hence the structure and function of circuits over time.
What are the two ways that synaptic plasticity can present itself in memory formation?
Long term potentiation - persistent increase in synaptic strength due repetitive stimulation
Long term depression - repetitive stimulation of synapses causes a reduction in synaptic strength.
What are some signs of long term potentiation?
Synpatic boutons increase in size
Synpatic boutons increase in activity
What is important to rember regarding synapses and activity within the brain?
Multiple synapses (like thousands) are happening at the same between between multiple different brain areas, this allows the higher level cognition of humans e.g imagination.
These patterns can be ‘learnt’ to influence the behaviour patterns.
Why are the basal ganglia important in relation to the limbic system?
The basal ganglia have a loop with the limbic system, this regulates what emotions are being felt. This explains why we can’t feel happy and sad at the same time
This connection is between the ventral striatum (made of limbic system nucleus accumbens and olfactory tubercule) and the dorsal striatum (BG caudate nucleus and putamen).
What modulates the motor basal ganglia pathway?
The nigrostriatal pathway
The substantia nigra release of dopamine.
This is shown through the direct and indirect basal ganglia pathways.
What modulates the limbic basal ganglia pathway?
The ventral tegmental area - regulates reward consumption and motivation (hence the emotional link)
Links to the thalamus and the striatum.
Name the red structures
The olfactory bulb
The olfactory tract
The olfactory tubercule
The piriform cortex
Name the green structures
The amygdala
The entorhinal cortex
Name the blue label,
The optic chiasm
What is the purpose of the circuit of papez?
To give emotional meaning to episodic memories, has a survival advantage.
What cranial nerves have parsympathetic routes?
The oculomotr nerves (111)
The vagus (x)
The glassopharangeal (ix)
The facial (VII)
What is the black structure?
The neocortex
What is the blue structure in the image?
The cingulate gurus
What is the green structure in the image?
The hippocampus and the fornix
What is the red structure in the image?
The hypothalamus
What is the yellow structure in the image?
The anterior nuclei of the thalamus
Draw a simplified diagram to represent the Papez ciruit.
What is the red and purple structure?
Red is the amydala
Purple is the mammillary bodies
Explain how the hippocampus and the amygdala may be found on coronal cross section.
In the temporal lobe (deep and medial)
The hippocampus is posterior the the amygdala
Label the following image
- Thalamus
Fornix
Basal forebrain
Prefrontal cortex
Mammillary bodies
Amygdala
Rhinal cortex
Hippocampus
Describe the location of the hippocampus in relation to the ventricles.
Main body is located just inferior to the temporal horn of the lateral ventricle
The curvature then is deep and medial to the lateral ventricle
ADD IMAGE FROM COMPLETE ANATOMY.
Draw a simple diagram to show how the hippocampus can connect to sensory information and the rest of the cortex.
