Learning and Memory revision Flashcards
In epilepsy, are neurons firing synchronously or dysynchronously?
synchronously
that’s what causes the seizure
What causes epileptic seizures?
Sudden excitation in group of neurons with loss of inhibitory potential
What happens at excitatory synapses?
If glutamate is released into synapse, makes it more likely next neuron will fire
Is epilepsy caused by increase in glutamate or reduction in GABA?
reduction in GABA
What has informed us more than anything else about memory function?
TLE
What is TLE?
recurrent unprovoked seizures originating from medial or lateral temporal lobe
What does medial, lateral mean?
Middle, outside
What is difference between simple or complex seizure?
simple = auras
complex = loss of consciousness
All TLE’s start simple
What is sclerosis?
deterioration of cells or cell death
What else causes TLE?
past infections, tumours, vascular malformation
Is TLE usually bilateral or unilateral?
unilateral
What was resected in HMs surgery?
Amygdala, hippocampi, part of parahippocampal gyri
What is retrograde amnesia?
Impairment for memories created prior to injury
What is anterograde amnesia?
Can’t learn new things
Can’t recall experiences / information learnt after injury
What is declarative memory?
Ability to consciously access information
What was HM’s ability re declarative and procedural memory?
Declarative: very bad
Procedural: fine
How is procedural memory developed?
repetitive practice
What do left MTL lesions result in?
Verbal memory impairment
What do right MTL lesions result in?
Non-verbal / visual memory impairment
Does TLE lead to memory impairment?
Yes
What is verbal v non-verbal memory impairment?
verbal = language based [written and spoken] non-verbal = non-language based [visual]
What is hippocampus proper?
Ammon’s Horn [CA1 to CA3]
What is hippocampal formation?
dentate gyrus, CA1, CA3, subiculum
Where does entorhinal cortex receive info from?
parahippocampal and perirhinal cortices
What does hippocampus do with different modes of memory?
Puts them all together - can know what we saw, what we felt, what we touched
What is consolidation theory of memory?
After a period of consolidation, information can be retrieved independently of hippocampal information [Squire]
What is multiple trace theory of memory?
Retrieval of autobiographical / episodic experiences always involves hippocampal system [Moscovich]
Which part of brain is particularly important for relational memory tasks? [eg name with face, meaning with a word]
Hippocampal system
How do we test relational memory?
paired association task [between arbitrarily things]
What are the three regions of the extra-temporal brain that are involved in memory?
Papez’s circuit
frontal lobes
diencephalon
What does Papez’s circuit include?
mamillary bodies [hypothalamus] fornix ATN [thalamus] cingulate gyrus hippocampus
What is process of Papez’s circuit
hippocampus - fornix - mamillary bodies - ATN - cingulate cortex - hippocampus
What do lesions to Papez’s circuit result in?
Declarative memory impairment
Which parts of papez’s circuit are most likely to be lesioned in declarative memory impairment?
Hippocampal
ATN
Where is spatial memory most likely formed?
right hippocampal lesions
What do the frontal lobes do?
Motor programming [motor and premotor cortices - posterior FL]
Cognitive control processes [prefrontal cortex]
What are cognitive control processes?
problem solving, reasoning, planning, monitoring, self correction
Where are strategies for memory encoding and retrieval developed and implemented?
Frontal lobes
Where are contextual details of memories stored?
DLPF
What is the diencephalon comprised of?
Thalamus and hypothalamus
Where are mamillary bodies?
Component of hypothalamus
What is dorsal medial nuclei of thalamus involved in?
Deficits in selecting appropriate information to be retrieved
What is intralaminar/midline nuclei of thalamus involved in?
deficits in memory, memory retrieval
What is ion released into cell in excitatory synapse?
Sodium
What is released in an inhibitory synapse?
Potassium
What does LTP cause?
More receptors to be added to post synaptic cell
What are the long term synaptic changes in LTP?
Increased sensitivity of receptors to glutamate
Increased amount of glutamate released by pre-synaptic cell
Protein synthesis in post-synaptic dendrites
Where is LTP most likely to occur?
Hippocampus, entorhinal cortex
What do postsynaptic receptors do?
Detect the presence of neurotransmitters in the synaptic cleft
What is the ‘docking’ of synaptic vesicles?
When clusters of protein molecules attach to other protein molecules in presynaptic membrane
What opens the calcium channels in presynaptic membrane?
depolarisation of membrane by action potential
What ions depolarise the post-synaptic cell?
Sodium [most important], Calcium
What ions hyperpolarise the postsynaptic cell?
potassium
what does depolarisation of postsynaptic cell cause?
EPSP
What does hyperpolarisation of postsynaptic cell cause?
IPSP
What does opening of chloride channels in postsynaptic cell do?
neutralises EPSPs
