Week 8 - limbic system Flashcards
Limbic system
amygdala, hippocampus, thalamus, hypothalamus, basal ganglia, and cingulate gyrus, forinx, amygdala-hypothalamic fibres
What does the forinx provide?
fibre connection between hippocampus and hypothalamus
What does the amygdala-hypothalamic fibres provide?
pass from amygdala complex to the hypothalamus through the stria terminalis
How can you recognise the amygdala in a cross section?
thickening of the cortical tissue
What’s the function of the amygdala?
emotion, memory
Explain the papez circuit
neocortex (emotional colouring) contacts/ contacted <-> cingulate cortex (emotional experience) -> hippocampus -> hypothalamus via forinx (exmopitonal expression) -> anterior nucleus of thalamus -> back to cingulate cortex
What were the original components of the limbic system?
hypothalamus with mammilary bodies, anterior nucleus of thalamus, cingulate cortex, hippocampus
What did papez incorrectly believe?
that there is a circuit of working memory, keeping memory in constantly reverberating networks - now it is considered for emotional processing and emotional regulation of behaviours
What is the official composition of the limbic system?
- cingulate gyrus
- parahippocampal gyrus
- amygdaloid body
- hippocampus
name the four subdivisions of the amygdala
- basolateral amygdala
- olfactory amygdala
- centromedial amygdala
- extended amygdala
What is the basolateral group of the amygdala?
basal nuclei, lateral nucleus
What s the corticomedial group of the amygdala?
central and cortical nucleus
BSTL
bed nucleus of stria terminalis
BSTM
basal nucleus of meynert
What does the basolateral amygdala do?
receives highly processed information form modality specific cortical association areas and through reciprocal connections affects processing of sensory information
can also affect cortical procession via reciprocal thalamoamygdaloid and stratal connections
what is the function of the olfactory amygdala?
- receives input form both olfactory bulb and olfactory cortex and is involved in processing of olfactory information
- projects to ventromedial amygdala and hypothalamus
What is the function of the centromedial and extended amygdala?
- receive primary inputs form hippocampus formation, insulation and orbitofrontal cortex (also cerebral cortex) and other parts of amygdala
- project to regions in hypothalamus and brainstem
- support and affect autonomic, endocrine and somatomotor aspects of emotional and eating, drinking, sexual behaviour
Give an example of psychological testing relating to the amygdala
- pavolovs dog experiment with classical conditioning
What animal looks like the forinx ?
seahorse
Explain HM
temporal lobe epilepsy
removal of parts of hippocampus and amygdala
post surgery HM was unable to make new episodic memories
declarative memories were affected -> parts of hippocampus were missing and important fibre tracts were destroyed
What kind of memory does the hippocampus relate to?
declerative memory
What kind of memory does the amygdala + cerebellum relate to
non-declarative - simple classical conditioning
What does the transverse hippocampus slice looks like?
Horn of Ammon
Explain the hippocampus try-synaptic circuit
- entorhinal cortex activates granular cells in dentate gyrus via performant pathway
- granular cells of dentate gyrus give rise to Mossy fire axons that innervate CA3 pyramidal cells via giant mossy fibre boutons
- CA3 pyramidal cells send axons via Schaffer collateral pathway to CA1 area where they activate CA1 pyramidal cells via en passant boutons
What is the function of the three synapses int he tri-synaptic circuit?
exhibit synaptic plasticity, such as long-term potentiation, albeit some of the mechanisms involved are quite dissimilar
is the hippocampus involved in spatial memory?
yes - +ve correlation between size and time spent as a taxi driver
Explain Jennifer Aniston neurons
- same hippocampus cells reacted when they saw an image, her name, heard her voice
- cells in hippocampus respond to different people, objects, places
-> not just involved in LTM but also working memory
