Module 7 - The Limbic System Flashcards
What does limbic mean?
Latin for boarder
The limbic system refers to a collection of cortical and subcortical regions of the brain primarily associated with regulating emotion, motivation, learning and memory. What are the major components of the limbic system?
- The limbic lobe
- The hippocampus
- The amygdala
What are the three cor components of the limbic lobe?
Parahippocampal gyrus, cingulate gyrus, uncus
Where is the hippocampus located?
Deep within the temporal lobe. It serves as the floor of the inferior horn of the lateral ventricle.
Where is the amygdala located?
Just rostral/anterior and medial to the hippocampus
What are the three core functions of the hippocampus?
- Learning
- Memory formation
- Site of adult neurogenesis
What are the three core functions of the amygdala?
- emotional learning and memory
- fear
- reward
The hippocampus contains long-term and short-term memory. What can long term memory be subdivided into?
- Declarative (explicit)
- Nondeclarative (implicit) - skills, habits, emotional memories, conditioned reflexes
What are the 2 kinds of declarative memory?
- Episodic (events)
- Semantic (facts)
The amygdala can be said to act as an emotional “saliency filter”, what does this mean?
It allows you to decide which emotional stimuli are important
The hippocampus is easily identifiable in cross section due to its position just below the inferior horn of the lateral ventricle. Locate:
- the hippocampi
- the inferior horns of the lateral ventricles
The amygdala can be identified by locating the uncus, as the amygdala is just deep to the uncus. Where is the amygdala?
The Papez Circuit comprises the below 5 structures. Find them.
- hippocampus
- mammillary body
- thalamus
- cingulate gyrus
- Fornix
The fornix can be divided into what 4 areas?
- Columns
- Body
- Crus
- Fimbria
What did Dr. James Papez propose?
That the experience of emotion was mediated by an underlying neural circuit involving the limbic system and specific cortical areas
The fornix carries output from the X to the Y, the most posterior nuclei of the hypothalamus
hippocampus
mammillary bodies
The fornix carries output from the hippocampus to the mammillary bodies, the most posterior nuclei of the hypothalamus. From there information travels via the X to the Y
mammillothalamic tract
anterior nucleus of the thalamus
The fornix carries output from the hippocampus to the mammillary bodies, the most posterior nuclei of the hypothalamus. From there information travels via the mammillothalamic tract to the anterior nucleus of the thalamus.
From the anterior nucleus of the thalamus, projections travel through the X and terminate in the Y
internal capsule
cingulate gyrus
The fornix carries output from the hippocampus to the mammillary bodies, the most posterior nuclei of the hypothalamus. From there information travels via the mammillothalamic tract to the anterior nucleus of the thalamus.
From the anterior nucleus of the thalamus, projections travel through the internal capsule and terminate in the cingulate cortex
Finally, output from the cingulate gyrus can travel via the X to the Y, and at the same time, can project to widespread areas of the cortex
cingulum
hippocampus
Describe the Papez circuit.
It functions as a neuroanatomical substrate of emotion and memory by connecting areas of cortex with the rest of the limbic system - thus allowing for top-down cortical control of emotional responses
What do we now know about the Papez circuit?
That Papez was basically correct, but that his concept was not complete. Other areas are structurally and functionally connected with the circuit described by Papez.
Are most tracts associated with the limbic system unidirectional or bi-directional?
bidirectional in nature
What are the 3 structures indicted here
1 = cingulate gyrus
2 = uncus
3 = parahippocampal gyrus
What structure lies deep to the area of cortex below?
Amygdala
What structure lies deep to the area of cortex indicated below?
The hippocampus
What is this area of the brain? What is it implicated in?
Hippocampus. Implicated in: learning, memory, and it is the site of adult neurogenesis
What is this structure? What would bilateral lesions to this area be associated with?
Amygdala
Emotional changes, e.g., reduced fear of dangerous stimuli
What structure overlies the amygdala and hippocampus?
The uncus
What does the limbic lobe comprise?
- parahippocampal gyrus
- Cingulate gyrus
- Subcallosal gyrus
The limbic lobe is comprised of three gyri, the parahippocampal, cingulate, and subcallosal gyri. What fiber bundle are they connected by?
The cingulum
What are the subcortical limbic structures?
hippocampus, amygdala, and septal nuclei
What is the anterior part of the parahippocampal gyrus?
The entorhinal cortex
What is the function of the entorhinal cortex?
The entorhinal cortex receives input from widespread cortical association areas, including somatosensory and prefrontal areas, and relays information between the hippocampus and cortical association areas.
On this midsagittal section, locate the:
- cingulate gyrus
- parahippocampal gyrus
- uncus
On this dissection of the limbic system, identify the:
- Columns of the fornix
- Body of the fornix
- Crus of the fornix
- Hippocampus
On this photograph of the limbic system, identify:
- the hippocampus
- the amygdala
On this micrograph of the diencephalon/basal ganglia (#12), locate the fornix.
On this micrograph of the diencephalon/basal ganglia (#12), locate the amygdala.
On this micrograph of the diencephalon/basal ganglia (#13), locate the:
- amygdala
- fornix
- amygdala (grey)
- fornix (red)
On this micrograph of the diencephalon/basal ganglia (#14), locate the fornix
On this micrograph of the diencephalon/basal ganglia (#15), locate the:
- fornix
- anterior commissure
- fornix (red)
- anterior commissure (pink)
On this micrograph of the anterior diencephalon (#16), locate the:
- columns of the fornix
- anterior commissure
- columns of the fornix (red)
- anterior commissure (purple)
On this coronal section of the brain, locate the amygdala
On this coronal section of the brain, where is the anterior commissure?
On this coronal section of the brain, where is the hippocampus?
On this coronal section of the brain, where is the hippocampus?
On this coronal section of the brain, where is the hippocampus?
On this coronal section of the brain, where is the hippocampus?
What are the 5 main blood vessels that serve much of the limbic system?
- anterior cerebral artery
- posterior cerebral artery
- anterior choroidal artery
- Circle of Willis
What supplies blood to the cingulate gyrus?
Branches of the anterior cerebral artery as it loops around the genu of the corpus callosum
What supplies blood to the parahippocampal gyrus?
Temporal branches of the posterior central artery
What supplies blood to the uncus?
Primarily the uncal arteries, which are branches of the middle cerebral artery
What limbic structures does the anterior choroidal artery serve?
The hippocampal formation, the amygdala, the tail of the caudate, the sublenticular and retrolenticular limbs of the internal capsule
What is the different between olfactory inputs and inputs from other senses?
From the olfactory bulb, signals are sent directly to the cortex, bypassing the thalamus. All other sensory inputs synapse in the thalamus before reaching the cortex.
Which cranial nerve is the olfactory nerve?
CN 1
On this image of the brain, locate the:
- olfactory bulb
- olfactor tract
- optic nerve
- optic chiasm
- optic tract
