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

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.

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First study of EEG morphology using simultaneous intracranial EEG-fMRI in humans

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The duration of sharp waves is significantly correlated with the BOLD signal amplitude.

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BOLD amplitude reflects more field potential duration than neuronal synchrony.

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Sharp wave duration should be included in BOLD models of epileptic discharges.

The last resort: regulation by law

Within the health professions the diminished constraint of conscience and custom upon aggrandizement, acquisitiveness, and exploitation has given rise to the increased role of the government in regulating health care delivery. This situation will continue to exist in direct proportion to the public's convictions that the private sector is incapable of satisfying public expectations. Conversely, when the health care profession, as a whole, recommits itself to a sense of stewardship and accountability to patients and the community, the present system of regulation will pass.