NeuroAnatomy - Lecture 13 - Limbic System Flashcards
What is the limbic system’s function?
controls the functions that are necessary for self-preservation and species survival
What are some of the roles the limbic system controls?
sleep/wake cycle, feeding/appetite, sexual reproduction/nurturing, fight/flight, motivation/addiction
What cortical structures make up the limbic system?
cingulate gyrus, parahippocampal gyrus, amygdala
What subcortical structures make up the limbic system?
hypothalamus, mammillary bodies, septal nuclei, anterior thalamic nuclei, fornix, stria terminalis, olfactory tract
What is the function of the septal nuclei?
located in prefrontal cortex, associated with pleasure and reproduction
What is the function of the fornix?
connects the mammillary bodies to the hippocampus
What is the function of the stria terminales?
connects the amygdala to the hypothalamus
What is the function of the cingulate gyrus?
processes emotions and sensations with actions // modifies behavior and communicates with motor, endocrine, and autonomic systems
What is the function of the parahippocampal gyrus?
acts as a staging area for memory formation
sensory information enters the parahippocampal gyrus and is sent to hippocampus to be developed into long term memory
What is the function of the hippocampus?
central role in memory formation // sensory information is sent to entorhinal cortex of parahippocampal gyrus to be stored
What happens if there is a bilateral lesion/damage to the hippocampus?
patient is unable to form new long-term memories, but previous long-term memories can still be retrieved due to being stored in other areas of cortex
What is the function of the hypothalamus?
maintains homeostasis, regulates endocrine/autonomic/behavioral/sexual functions
Where is the amygdala located?
deep within the uncus
What is the function of the amygdala?
generates behavioral responses to sensory stimuli (fear, anger, rage, anxiety) // provide instinctive behavorial responses relating to human survival
What is the short loop pathway of the amygdala?
thalamus sends sensory input to amygdala –> amygdala processes info and generates emotional survival response –> stored as implicit memory
What is the long loop pathway of the amygdala?
thalamus sends sensory input to cortex –> uses explicit memory to decide how to act in response to stimuli –> cortex/hippocampus shares memory with amygdala –> amygdala compares it’s implicit memory to learned explicit memory to generate a modified emotional response
What is the difference between implicit and explicit reponses?
implicit = fast/quick response, instinctive or reaction, short loop // explicit = slower response, response was thought out, long loop
What is an amygdala hijack?
an abrupt inappropriate emotional response followed by post-response realization of the response was inappropriate
What occurs when there is a lesion to the amygdala?
reduced emotional responses to stimuli
What is Kluver-Bucy Syndrome?
rare bilateral lesion to amygdala resulting in tame, non-aggressive behavior
What occurs when there are Irritative lesions (seizures) of the amygdala?
strong emotions of fear/panic, loss of control, hyperactivity
The amygdala is involved in the fear, anger, anxiety responses… but what else is it involved in?
pleasure and reward pathways // part of the dopaminergic pathways
What is the memory pathway “hierarchy?”
sensory memory (fleeting memory) –> attention –> short term memory –> long term memory
How long does sensory memory last?
a few seconds, anywhere from 0.3 - 10 seconds
