Projects per year
Abstract
Objective
The objective of this study was to investigate whether previously reported early blood oxygen level dependent (BOLD) changes in epilepsy could occur as a result of the modelling techniques rather than physiological changes.
Methods
EEG-fMRI data were analysed from seven patients with focal epilepsy, six control subjects undergoing a visual experiment, in addition to simulations. In six separate analyses the event timing was shifted by either −9,−6,−3,+3,+6 or +9 s relative to the onset of the interictal epileptiform discharge (IED) or stimulus.
Results
The visual dataset and simulations demonstrated an overlap between modelled haemodynamic response function (HRF) at event onset and at ±3 s relative to onset, which diminished at ±6 s. Pre-spike analysis at −6 s improved concordance with the assumed IED generating lobe relative to the standard HRF in 43% of patients.
Conclusion
The visual and simulated dataset findings indicate a form of “temporal bleeding”, an overlap between the modelled HRF at time 0 and at ±3 s which attenuated at ±6 s. Pre-spike analysis at −6 s may improve concordance.
Significance
This form of analysis should be performed at 6 s prior to onset of IED to minimise temporal bleeding effect. The results support the presence of relevant BOLD responses occurring prior to IEDs.
The objective of this study was to investigate whether previously reported early blood oxygen level dependent (BOLD) changes in epilepsy could occur as a result of the modelling techniques rather than physiological changes.
Methods
EEG-fMRI data were analysed from seven patients with focal epilepsy, six control subjects undergoing a visual experiment, in addition to simulations. In six separate analyses the event timing was shifted by either −9,−6,−3,+3,+6 or +9 s relative to the onset of the interictal epileptiform discharge (IED) or stimulus.
Results
The visual dataset and simulations demonstrated an overlap between modelled haemodynamic response function (HRF) at event onset and at ±3 s relative to onset, which diminished at ±6 s. Pre-spike analysis at −6 s improved concordance with the assumed IED generating lobe relative to the standard HRF in 43% of patients.
Conclusion
The visual and simulated dataset findings indicate a form of “temporal bleeding”, an overlap between the modelled HRF at time 0 and at ±3 s which attenuated at ±6 s. Pre-spike analysis at −6 s may improve concordance.
Significance
This form of analysis should be performed at 6 s prior to onset of IED to minimise temporal bleeding effect. The results support the presence of relevant BOLD responses occurring prior to IEDs.
| Original language | English |
|---|---|
| Pages (from-to) | 245-253 |
| Journal | Clinical Neurophysiology |
| Volume | 127 |
| Issue number | 1 |
| Early online date | 17 Jul 2015 |
| DOIs | |
| Publication status | Published - Jan 2016 |
Keywords
- Visual stimulation
- Pre-spike response
- Epilepsy
- Haemodynamic response function
- simulations
- EEG-fMRI
Fingerprint
Dive into the research topics of 'Early haemodynamic changes observed in patients with epilepsy, in a visual experiment and in simulations'. Together they form a unique fingerprint.Projects
- 1 Finished
-
Development of Single Trial EEG-fMRI: Investigations of Dynamic Brain Function at High Temporal and Spatial Resolution
Bagshaw, A. (Principal Investigator), Derbyshire, S. (Co-Investigator), Kourtzi, Z. (Co-Investigator) & Miall, C. (Co-Investigator)
Engineering & Physical Science Research Council
1/03/08 → 28/02/11
Project: Research Councils