1 research outputs found
Abnormal network oscillations in patients with Dementia with Lewy bodies and a mouse model of alpha-synucleinopathy
Ph. D. Thesis.Electrophysiology can reveal changes in neuronal oscillatory activity in the brain
in relation to neurodegenerative disorders, including dementia with Lewy bodies (DLB).
DLB, characterised by abnormal Ī±-synuclein (Ī±-syn) aggregation within neurons, is the
second most common cause of dementia after Alzheimerās disease (AD). This thesis
had two aims. Firstly, to identify resting-state EEG changes that reflect cognitive
fluctuations, a DLB core symptom, and differentiate DLB from AD and Parkinsonās
disease dementia (PDD) patients and healthy controls. Secondly, to detect
electrophysiological alterations in young mice over-expressing human mutant Ī±-syn
while under urethane-induced anaesthesia, mimicking deep-sleep. The resulting slowoscillation (SO) composed of Up-states (neuronal firing) and Down-states (neuronal
āsilenceā), was recorded intra-cortically, from the hippocampus and medial prefrontal
cortex (mPFC). The human EEG analysis replicated reports of a shift of power and
dominant frequency (DF) from alpha to theta frequencies, in DLB/PDD patients
compared to AD patients and controls. Contrary to previous work, the DF variability
(DFV) over time was increased in AD and not in DLB/PDD patients, although a DLBspecific correlation between the DFV and cognitive fluctuations persisted. The DFV
and power/DF distribution could differentiate between AD and DLB patients with high
sensitivity (92.26%) and specificity (83.3%). Analysis of sleep patterns in Ī±-syn mice
in both the mPFC and hippocampus revealed increased SO frequency, aberrant
neuronal firing activity on Down-states, altered power distribution on Up-states and
disturbed sleep spindle activity, compared to WTs. A novel infra-slow modulation (ISM)
was described in WTs, presenting as bursts of power across frequencies every ~ 3.5
min. In Ī±-syn mice, the ISM induced abnormally high levels of high frequency
oscillatory power in the hippocampus. Our findings indicate altered neuronal oscillatory
activity in DLB patients and Ī±-syn mice during rest and sleep respectively, suggesting
that Ī±-syn affects the integrity of the networks underlying widespread, synchronous
activity.Alzheimerās Societ