Post-graduate theses
Current Record: 91 of 824
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Identifier |
000438383 |
Title |
Analysis of the activity patterns in focal cortical seizures using the 4-AP model |
Alternative Title |
Ανάλυση των μοτίβων δραστηριότητας στις εστιακές επιληπτικές κρίσεις χρησιμοποιώντας το 4-ΑΡ μοντέλο |
Author
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Ασβεστοπούλου, Θωμαΐς Ε.
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Thesis advisor
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Παπαδοπούλη, Μαρία
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Reviewer
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Τσαμαρδινός, Ιωάννης
Smirnakis, Stelios
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Abstract |
Epilepsy affects about 3% of the worldwide population. It is characterized by
the repeated occurrence of highly synchronized and unprovoked bursts of neuronal
activity, known as seizures. However, our understanding of how neurons interact
to generate the abnormal network activity patterns that underlie ictogenesis is
limited. It is important to understand what changes in the cortical circuit allow
a highly-correlated firing state to emerge, evolve, and recur. To analyse the emergence and spread of focally initiated seizures, we used the 4-aminopyridine (4-AP)
model, a well-established, reliable model of acute focal neocortical seizures. Using the calcium indicator GCaMP6s with in vivo two-photon cellular microscopy,
we examined the activity profiles of individual neurons in layer 2/3 (L2/3) of the
visual cortex during focal seizures induced by 4-AP injections in mice.
We identified significant activity epochs in this context using two methodologies: a novel methodology based on the identification of the noise intervals of
the fluorescence signal of each neuron, and another one based on the Recurrence
Quantification Analysis, a powerful tool based on the topological analysis of the
phase space of the underlying dynamics. Their results are consistent in terms of
the presence of significant activity epochs and their duration. These approaches
enable the identification of the onset of events of significant activity, aiming to
dissect the mechanisms of seizure initiation and recruitment of neurons within the
field of view.
We also characterized the functional network connectivity using graph-theoretical
metrics, such as normalized degree of connectivity, clustering coefficient, and
weighted clustering coefficient. To capture the contribution and influence of a
neuron to the connectivity of the network within a larger region, we introduced
the affinity, a belief-propagation-based metric, that integrates the pairwise temporal correlation of the firing events of neurons in a sub-network. The analysis reveals
the structure of the functional networks after the 4-AP injection, the significant
increase of the temporal correlation of neurons, and the influence of neurons in the
region close to the 4-AP injection. It comparatively examines the findings with
other network architectures, including the functional network of the control (prior
to the injection) as well as random graphs with well-defined structure.
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Language |
English |
Subject |
Focal epilepsy |
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Mouse |
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Single neuron resolution |
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Εστιακή επιληψία |
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Ποντίκι |
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Σε επίπεδο νεύρωνα |
Issue date |
2021-03-26 |
Collection
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School/Department--School of Sciences and Engineering--Department of Computer Science--Post-graduate theses
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Type of Work--Post-graduate theses
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Permanent Link |
https://elocus.lib.uoc.gr//dlib/3/a/4/metadata-dlib-1615981973-351645-19711.tkl
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Views |
554 |