Limbic System Flashcards
What are the cortical structures of the limbic system?
Parahippocampal gyrus
Cingulate gyrus
Insular cortex
Orbitofrontal cortex
Prefrontal association cortex
What are the subcortical structures of the limbic system?
Amygdala
Ventral striatal structure
Thalamic nuclei - anterior and mediodorsal
Hypothalamus - anterior, posterior, mamillary nuclei
Ventral tegmental area
What is the role of the insular cortex?
Empathy and theory of mind
What is the role of the orbitofrontal association cortex?
Neocrotical area invovled in the integration of personality and emotional behavior
What is the role of the prefrontal association cortex?
Executive function, working memory, and default mode network
What is the role of the cingulate gyrus?
Papez circuit
Emotional modulation of pain, cortical regulation of basic autonomic functions, and memory
Internal cognition
What is the role of the parahippocampal gyrus?
Learning and memory processes
What is the role of the entorhinal cortex (Area 28)?
Located in the anterior portion of the parahippicampal gyrus
Major relay for inputs and outputs between the association cortex and hippocampal formation
First cortical area to degenerate in AD
What is the role of the dentate gyrus?
Undergoes neurogenesis throughout life
Memory
What is the role of the intrinsic hippocampal circuit?
Association cortex –> Entorhinal cortex –>hippocampus proper (via alvear and perforant pathways)
From here projections sent to various areas of the hippocampus and dentate gyrus
Feedback loop is created
What is the role of the fornix?
Major output, three targets:
Medial and lateral mammillary nuclei
Lateral septal nucleus
Anterior thalamic nucleus
Describe the papez ciruit
Hippocampus to mamillary bodies via fornix –> anterior thalamic nucleus via the mammillothalamic tract –> Cingulate gyrus via internal capsule –> back to the entorhinal cortex and hippocampus via the association pathway
What is the role of the septal nuclei?
Endogenous reqard circuits
Receives input from the hippocampus, amygdala, hypothalamus, and ventral tegmental area
What is the role of the amygdala?
Interpret and recall emotional content and olfactory memories, visual inputs and response
Fight or flight response, modd, and emotion
What input does the amygdala receive?
Highly processed sensory information
Autonomic input
What occurs from a lesion to the amygdala area of the brain?
Dysregulation of emotion
Docility, outbursts, rage, aggression, hyperphagia
What are the medial diencephalic structures of the limbic system?
Anterior and mediodorsal nuclei of the thalamus
Mammillary bodies
Important for memory
What are the medial temporal lobe structures of the limbic system?
Entorhinal cortex and the hippocampal formation
Reciprocal connections with the multimodal association cortex and are important for memory
What results from bilateral damage to either MDS or MTLS?
Loss of declarative or explicity memory
Implicit memory remains intact
What is Kluver-Bucy syndrome?
Results from temporal lobe resection or viral encephalitis
Hypersexuality, hyperphagia, increased curiosity, los of fear, reduced anger, dementia-like symptoms
What disorders can result from amygdala hyperactivation?
Anxiety, panic attacks, PTSD, OCD
Occlusion of which arteries will result in memory loss?
PCA
Superior portion of the basilar artery - more memory loss because it gives rise to both PCAs which supply the MTLS and MDS
How can seizures affect memory loss?
Seizure-induced memory loss can occur with complex partial and generalized tonic-clonic seizures
If severe enough to cause hippocampal sclerosis, then memory loss can persist
What is transient global amnesia?
Sudden and temporary onset of both retrograde and anterograde amnesia
85% of patients only have one episode, associated with extreme stress
How can Wernike-Korsakoff syndrome affect the limbic system?
Can result in the degnereation of the MDS nuclei and hippocampal degeneration
Results in amnesia, poor impulse control and confabulation
