Correlation between volumetric oxygenation responses and electrophysiology identifies deep thalamocortical activity during epileptic seizures

Abstract

Abstract. Visualization of whole brain activity during epileptic seizures is essential for both fundamental research into the disease mechanisms and the development of efficient treatment strategies. It has been previously discussed that pathological synchronization originating from cortical areas may reinforce backpropagating signaling from the thalamic neurons, leading to massive seizures through enhancement of high frequency neural activity in the thalamocortical loop. However, the study of deep brain neural activity is challenging with the existing functional neuroimaging methods due to lack of adequate spatiotemporal resolution or otherwise insufficient penetration into subcortical areas. To investigate the role of thalamocortical activity during epileptic seizures, we developed a new functional neuroimaging framework based on spatiotemporal correlation of volumetric optoacoustic hemodynamic responses with the concurrent electroencephalogram recordings and anatomical brain landmarks. The method is shown to be capable of accurate three-dimensional mapping of the onset, spread, and termination of the epileptiform events in a 4-aminopyridine acute model of focal epilepsy. Our study is the first to demonstrate entirely noninvasive real-time visualization of synchronized epileptic foci in the whole mouse brain, including the neocortex and subcortical structures, thus opening new vistas in systematic studies toward the understanding of brain signaling and the origins of neurological disorders.

Advanced optoacoustic methods for multiscale imaging of in vivo dynamics

“…A 256-element detection array system, which can record data at rates up to 100 frames/s [119] and is capable of tuning the laser wavelength on a per-pulse basis, provides multispectral information for analysing hemodynamic changes deep inside the mouse brain. This has recently been demonstrated in a model of focal epilepsy in which the onset, spread and termination of 4-Aminopyridine-induced epileptic seizures were visualized, with concurrent electroencephalographic (EEG) recording of the aberrant neural activity [101] (Fig. 15d).…”

“…Furthermore, the particular orientation of the detection elements provides good sensitivity in the imaged region of interest located around the geometric centre of the spherical detection geometry. The 4D optoacoustic imaging approach has enabled tracking of contrast agent perfusion in entire organs [97], beat-by-beat imaging of fast beating murine heart [100] or monitoring the distribution of epileptic seizures in whole mouse brains [101]. The same configuration is further suitable for handheld operation mode, and human angiographic imaging at centimetre-scale depths was demonstrated attaining nearly isotropic spatial resolution on the order of 200 μm [102].…”

“…(d) Intensity plots of the epileptic-seizure-related activity as identified by correlating electroencephalogram (EEG) traces with optoacoustic hemodynamic responses obtained using 5D optoacoustic tomography. Adapted with permission from [101]. © 2017 Society of Photo Optical Instrumentation Engineers.…”

Theranostic cranial implant for hyperspectral light delivery and microcirculation imaging without scalp removal

“…Indocyanine green video angiography (ICGVA) requires injection of dyes and cannot provide continuous assessment of vessel perfusion 13,14 . Optical coherence tomography (OCT) 15 , photoacoustic imaging (PAM) 16 , and fluorescence microscopy approaches like confocal microscopy or the two-photon variant 17 are based on laser scanning, which is limiting to the temporal resolution and field of view 18 , although recent technical improvements in OCT and PAM have been reported which provide sufficient temporal resolution for epileptic seizure monitoring [19][20][21] . Fast full-field laser Doppler perfusion imaging (ffLDPI) 17 cannot simultaneously provide microvascular structural and functional information due to lack of adequate spatiotemporal resolution 22 .…”

Intracerebral haemorrhage-induced injury progression assessed by cross-sectional photoacoustic tomography

“…It combines the advantages of optical contrast and acoustic detection, and holds great promise for small-animal imaging [13]. Previous works showed that PAT has great potential in various biological and medical applications such as vasculature visualization [14][15][16][17], arthritis diagnosis [20,21], neuroimaging [23,24].Our own previous work indicated that widely adopted horizontal plane PAT is a powerful tool to detect ICH morphology in small animals [17].…”