The hemodynamic responses to 4-aminopyridine (4-AP) induced focal epileptic spikes and electrical stimulations are compared in a rat model. Nonlinearities are quantified with biophysical models. Supranormal oxygen consumption from epileptic spikes is inferred. In one recording, interictal spikes followed an almost periodic pattern. Such rhythmic spiking is a well-documented phenomenon in electrophysiological studies, but the hemodynamics correlates have been less studied. Spikes occurred every 12.5 ± 1.0 s. Peaks in total hemoglobin (HbT), a proxy for regional cerebral blood volume, followed spikes by 2.6 ± 0.3 s. Troughs in HbT preceded spikes by 1.68 ± 1.2 s. The narrowness of this distribution is surprising. From it, one may derive a significant but paradoxical fall in HbT several seconds before the spikes, but which this decrease in HbT is better interpreted as being due to the interictal spike that occurred before.
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Philippe Pouliot ; Van Tri Truong ; Cong Zhang ; Simon Dubeau and Frédéric Lesage
Tight neurovascular coupling in a rat model of quasi-periodic interictal spiking using multispectral optical imaging
", Proc. SPIE 8412, Photonics North 2012, 841203 (October 23, 2012); doi:10.1117/12.2000717; http://dx.doi.org/10.1117/12.2000717