An investigation of the relationship between BOLD and perfusion signal changes during epileptic generalised spike wave activity

Carmichael, David W.; Hamandi, Khalid; Laufs, Helmut; Duncan, John S.; Thomas, David L.; Lemieux, Louis

doi:10.1016/j.mri.2008.01.041

Cited by 29 publications

(16 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the standard model of the BOLD effect, an increase in neuronal activity induces an increase in CBF, which provides more oxygen and glucose to the tissues; if the increase in CBF exceeds the simultaneous increase in oxygen consumption, the local concentration of deoxyhaemoglobin decreases and the intensity of the BOLD effect increases (Buxton, 2012). Due to the likely coupling between CBF and BOLD changes (Carmichael et al, 2008), the principal finding of this study -the duration of the sharp wave correlates significantly with the amplitude of the co-localised BOLD signal- is in line with both Geneslaw et al (2011) and Voges et al (2012).…”

Section: Discussionsupporting

confidence: 63%

“…Both IED onsets - related BOLD signal increases and decreases have been reported (Benar et al, 2006, Gotman et al, 2006, Grouiller et al, 2010, Jacobs et al, 2014, Lemieux et al, 2008, Moeller et al, 2009, Pittau et al, 2013, Salek-Haddadi et al, 2006). However, the mechanisms underlying BOLD signal decreases are not completely understood: they may result from (1) neuronal activity decreases (Shmuel et al, 2006) and associated CBF decreases (Carmichael et al, 2008), or (2) neuronal activity increases that lead to tissue oxygen consumption increases that exceed the simultaneous CBF increases, resulting in local deoxyhaemoglobin concentration increases (Schridde et al, 2008). Finding that a significant amount of the variance of BOLD signal decreases was explained by the sharp wave width suggests that BOLD decreases may not be necessarily associated with neuronal activity decreases (hypothesis (1)); our main finding and those of Geneslaw et al (2011) favour hypothesis (2).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

A study of the electro-haemodynamic coupling using simultaneously acquired intracranial EEG and fMRI data in humans

Murta

Tierney³

et al. 2016

NeuroImage

View full text Add to dashboard Cite

In current fMRI studies designed to map BOLD changes related to interictal epileptiform discharges (IED), which are recorded on simultaneous EEG, the information contained in the morphology and field extent of the EEG events is exclusively used for their classification. Usually, a BOLD predictor based on IED onset times alone is constructed, effectively treating all events as identical. We used intracranial EEG (icEEG)-fMRI data simultaneously recorded in humans to investigate the effect of including any of the features: amplitude, width (duration), slope of the rising phase, energy (area under the curve), or spatial field extent (number of contacts over which the sharp wave was observed) of the fast wave of the IED (the sharp wave), into the BOLD model, to better understand the neurophysiological origin of sharp wave-related BOLD changes, in the immediate vicinity of the recording contacts. Among the features considered, the width was the only one found to explain a significant amount of additional variance, suggesting that the amplitude of the BOLD signal depends more on the duration of the underlying field potential (reflected in the sharp wave width) than on the degree of neuronal activity synchrony (reflected in the sharp wave amplitude), and, consequently, that including inter-event variations of the sharp wave width in the BOLD signal model may increase the sensitivity of forthcoming EEG-fMRI studies of epileptic activity.

show abstract

Section: Discussionsupporting

confidence: 63%

Section: Discussionmentioning

confidence: 99%

A study of the electro-haemodynamic coupling using simultaneously acquired intracranial EEG and fMRI data in humans

Murta

Tierney³

et al. 2016

NeuroImage

View full text Add to dashboard Cite

show abstract

“…This may explain the negative change in BOLD signal found in these areas coupled with epileptic activity, and confirms that the coupling between the BOLD and EEG signals remains intact (91). …”

Section: Cognitive Network Abnormalitiessupporting

confidence: 67%

Network Connectivity in Epilepsy: Resting State fMRI and EEGâ€“fMRI Contributions

2014

Self Cite

View full text Add to dashboard Cite

There is a growing body of evidence pointing toward large-scale networks underlying the core phenomena in epilepsy, from seizure generation to cognitive dysfunction or response to treatment. The investigation of networks in epilepsy has become a key concept to unlock a deeper understanding of the disease. Functional imaging can provide valuable information to characterize network dysfunction; in particular resting state fMRI (RS-fMRI), which is increasingly being applied to study brain networks in a number of diseases. In patients with epilepsy, network connectivity derived from RS-fMRI has found connectivity abnormalities in a number of networks; these include the epileptogenic, cognitive and sensory processing networks. However, in majority of these studies, the effect of epileptic transients in the connectivity of networks has been neglected. EEG–fMRI has frequently shown networks related to epileptic transients that in many cases are concordant with the abnormalities shown in RS studies. This points toward a relevant role of epileptic transients in the network abnormalities detected in RS-fMRI studies. In this review, we summarize the network abnormalities reported by these two techniques side by side, provide evidence of their overlapping findings, and discuss their significance in the context of the methodology of each technique. A number of clinically relevant factors that have been associated with connectivity changes are in turn associated with changes in the frequency of epileptic transients. These factors include different aspects of epilepsy ranging from treatment effects, cognitive processes, or transition between different alertness states (i.e., awake–sleep transition). For RS-fMRI to become a more effective tool to investigate clinically relevant aspects of epilepsy it is necessary to understand connectivity changes associated with epileptic transients, those associated with other clinically relevant factors and the interaction between them, which represents a gap in the current literature. We propose a framework for the investigation of network connectivity in patients with epilepsy that can integrate epileptic processes that occur across different time scales such as epileptic transients and disease duration and the implications of this approach are discussed.

show abstract

“…In non-human primates, BOLD changes are best correlated to synaptic activity (local field potential) (Logothetis, Pauls et al 2001) but the coupling between cortical evoked potentials and haemodynamic responses might not show perfect spatial match (Disbrow, Slutsky et al 2000). In humans, non-invasive cerebral perfusion measurements suggested preserved neurovascular coupling in relation to generalised IED (Stefanovic, Warnking et al 2005;Carmichael, Hamandi et al 2008;Hamandi, Laufs et al 2008). The noninvasive study of the neurovascular coupling during epileptic activity in humans is limited by the poor sensitivity and low spatial resolution of scalp EEG (Alarcon, Guy et al 1994) and the resulting suboptimal characterisation of the baseline state.…”

Section: Neurophysiological Relevancementioning

confidence: 99%

Simultaneous intracranial EEG and fMRI of interictal epileptic discharges in humans

et al. 2011

Self Cite

View full text Add to dashboard Cite

Simultaneous scalp EEG-fMRI measurements allow the study of epileptic networks and more generally, of the coupling between neuronal activity and haemodynamic changes in the brain. Intracranial EEG (icEEG) has greater sensitivity and spatial specificity than scalp EEG but limited spatial sampling. We performed simultaneous icEEG and functional MRI recordings in epileptic patients to study the haemodynamic correlates of intracranial Interictal Epileptic Discharges (IED).Two patients undergoing icEEG with subdural and depth electrodes as part of the presurgical assessment of their pharmaco-resistant epilepsy participated in the study.They were scanned on a 1.5T MR scanner following a strict safety protocol.Simultaneous recordings of fMRI and icEEG were obtained at rest. IED were subsequently visually identified on icEEG and their fMRI correlates were mapped using a General Linear Model (GLM).On scalp EEG-fMRI recordings performed prior to the implantation, no IED were detected. icEEG-fMRI was well tolerated and no adverse health effect was observed. intra-MR icEEG was comparable to that obtained outside the scanner. In both cases, significant haemodynamic changes were revealed in relation to IED, both close to the most active electrode contacts and at distant sites. In one case, results showed an epileptic network including regions that could not be sampled by icEEG, in agreement with findings from magneto-encephalography, offering some explanation for the persistence of seizures after surgery.Hence, icEEG-fMRI allows the study of whole-brain human epileptic networks with unprecedented sensitivity and specificity. This could help improve our understanding of epileptic networks with possible implications for epilepsy surgery.4

show abstract

An investigation of the relationship between BOLD and perfusion signal changes during epileptic generalised spike wave activity

Cited by 29 publications

References 13 publications

A study of the electro-haemodynamic coupling using simultaneously acquired intracranial EEG and fMRI data in humans

A study of the electro-haemodynamic coupling using simultaneously acquired intracranial EEG and fMRI data in humans

Network Connectivity in Epilepsy: Resting State fMRI and EEGâ€“fMRI Contributions

Simultaneous intracranial EEG and fMRI of interictal epileptic discharges in humans

Contact Info

Product

Resources

About