Neuro 14: Limbic System Flashcards
(39 cards)
What are the 3 major olfactory epithelium?
- bipolar olfactory neurons
- sustentacular cells
- basal cells
–> you get progressive loss with age
organisation of olfactory system
- Olfactory neurones project into olfactory bulbs
- which synapse w/ 2nd order neurones (mitral cells)
- Forming an olfactory tract that travels to:
- Lateral + medial olfactory stria going to 2 places:
a) Piriform cortex of frontal lobe
b) Orbitofrontal cortex
o Connections to brainstem promote autonomic responses e.g. salivation when smell good food
Olfactory tract splits into :
- medial + lateral olfactory stria
most olfactory process takes place in the :
most olfactory process takes place in the :
a) piriform cortex
b) orbitofrontal cortex
–> connects to brainstem –> to cause autonomic responses
Define limbic system.
- the limbic system = rim or cortex adjacent to the corpus callous + diencephalon
what is the limbic system responsible for?
a) maintenance of homeostasis
b) agonistic behavior
c) sexual / reproductive behaviors
d) memory
How does the limbic system maintain homeostasis?
by:
- activation of visceral effector mechanisms
- modulation of pituitary hormone release
- initiation of feeding/drinking
- -> mainly hypothalamic function control
What are the 2 key parts of the limbic system?
and where are they found?
- amygdala
- hippocampus
found in the temporal lobe
What is the papez circuit?
- it is a neural circuit for the control of emotional expression
- amygdala + hippocampus = part of papez circuit
- cingulate cortex receives info from neocortex
- which passes it onto hippocampus via the cingulum bundle
- then passes through fornix –> into hypothalamus
- then there is projection to anterior nucleus of thalamus via MTT
- which projects back to cingulate cortex to perceive emotional experience
Where is the main afferent pathway of a hippocampus?
- perforant pathway
Where is the main efferent pathway of a hippocampus?
- fimbria/fornix
What is the function of the hippocampus?
- it is involved in memory + learning
What happens to the hippocampus in alzheimers disease?
- you get severe shrinking of the hippocampus
Where is the hippocampus located in?
- in the temporal lobe
- on the floor of lateral ventricles
the fornix lies immediate below the _____ _______
corpus callous
fibres of the fornix goes forwards –> and ends up in the _______ _____ at the base of the hypothalamus
fibres of the fornix goes forwards –> and ends up in the maxillary bodies at the base of the hypothalamus
note: hipocampus = penis shaped
-
What happens in cortical atrophy?
- there is a loss of neurons
- and ventricles = much larger than they should be
- there is hiding of the sulk
- frontotemporal = damaged more than alzheimer’s
What happens in early alzheimers
- hippocampus + entorhinal cortex = affected
- leads to short term memory problems
What happens in moderate alzheimers
- affects the parietal lobe
- dressing apraxia
What happens in late alzheimer’s
- affects the frontal lobe
- causes loss of executive skills
Where is amygdala located in?
- it is buried in the white matter of anterior temporal lobe
What are the main afferent connections of the amygdala?
- olfactory complex
- septum
- temporal neocortex
- hippocampus
- brainstem
What is the main efferent connections of the amygdala?
- stria terminalis
