Limbic system, memory, amnesia & dementia Flashcards
4 parts of the limbic system
cortical areas - cingulate gyrus, olfactory cortex
amygdala
hippocampus
mammillary bodies of hypothalamus
what are the main things associated with the amygdala and the hippocampus
amygdala - fear
hippocampus - memory
what do the mamillary bodies of the hypothalamus link the limbic system with?
endocrine system
function of limbic system
regulates emotions and memory formation
Main brain areas involved in memory formation
MTL
hippocampal formation
adjacent and connect cortical areas
areas of hippocampal formation involved in memory formation
cornu ammonis (CA1-3)
dentate gyrus
subiculum
Parts of the adjacent and connect cortical areas involved in memory formation
entorhinal cortex
perirhinal cortex
parahippocampal formation
case of HM
epilepsy - focal MTL lesion
anterograde and retrograde amnesia
short term memory and motor intact
skills used to demonstrate the case of HM
mirror drawing
rey-ostereith figure
2 MTL memory hypotheses
immediately store info, temporary buffer and ultimate storage in cortex
long term memory store in hippocampal formation with links to the cortex established during relearning or memorising
experiments testing MTL hypotheses
drugs to test acquisition and retention - lidocaine and TTx
support hypothesis 1
is hippocampal activity necessary for encoding or retrieving spatial memory or both?
both
declarative memory
episodic and semantic
non-declaritive memory
priming, habits, skills, implicit memories
what types of memory is the hippocampal formation crucial for?
episodic
what is neurodegenration and what happens?
ageing - nature and nurture
protein folding and aggregation
oxidative stress and calcium dishomeostasis
inflammation
loss of trophic factors and neuronal death
% of AD over 65 and over 85
10% and 50%
Areas of decline in AD
mental function, memory, acquired intellectual skills, orientation, abstract thinking, judgement
where are beta amyloid plaques and tau tangles found?
ba - outside cell and tau tangles inside cell
4 protein aggregations found in proteinopathies
beta amyloid
tau tangles
alpha synuclein
TDP-43
ABC score
thal stage - amyloid deposition
braak stage
CERAD neuritic plaque score
amyloid genetics
APP chromosome 21
trisomy 21
risk genes of AD associated with…
amyloid production, transport and clearance
inflammation
metabolic function
cytoskeleton function
cholinergic hypothesis
reduced ChAT - synthesis of Ach
lose cholinergic neurons
affect hippocampus and cortex
where are the majority of cholinergic neurons lost in AD?
nucleus basalis of meynert
AD neurotransmitters affected
glutamate, NE, serotonin
FFT EEG
most commonly used approach for spectral decomposition
heavily contaminated by noise
destroys info about time
spectral decomposition
separate out the frequencies and powers of the contributors
AR EEG
uses previous data points to predict next points
ignores noise
time resolved
AR in AD
resting EEG slowerd - decreased high power and increased low power
what does the slowing magnitude of AR correlate with
MCI –> AD
low frequency waves AR
delta - brain at rest
high frequency waves AR
beta-gamma : early in disease
Genetic risk factors - APOE
2% population have extra copy of APOE4 - greater risk of AD
current key hypotheses - neurodegeneration and memory loss in AD
APP processing and BA neurotoxicity hyperphosphorylation of Tau oxidative stress, ageing, metabolism diet metals
lifestyle risk factors
smoking, heart disease, depression, poor diet
?head trauma, infection, toxins
diagnosing AD
physical exam cognitive testing brain imaging eeg genetics blood and CSF post mortem
