Pre-seizure state identified by diffuse optical tomography

Abstract

In epilepsy it has been challenging to detect early changes in brain activity that occurs prior to seizure onset and to map their origin and evolution for possible intervention. Here we demonstrate using a rat model of generalized epilepsy that diffuse optical tomography (DOT) provides a unique functional neuroimaging modality for noninvasively and continuously tracking such brain activities with high spatiotemporal resolution. We detected early hemodynamic responses with heterogeneous patterns, along with intracranial electroencephalogram gamma power changes, several minutes preceding the electroencephalographic seizure onset, supporting the presence of a “pre-seizure” state. We also observed the decoupling between local hemodynamic and neural activities. We found widespread hemodynamic changes evolving from local regions of the bilateral cortex and thalamus to the entire brain, indicating that the onset of generalized seizures may originate locally rather than diffusely. Together, these findings suggest DOT represents a powerful tool for mapping early seizure onset and propagation pathways.

Towards real-time detection of seizures in awake rats with GPU-accelerated diffuse optical tomography

“…A method for fast DOT image reconstruction during rapidly changing neural dynamics was also achieved. Results suggest that early hemodynamic changes could be observed tens of seconds prior to seizure onset in awake rats, and confirms previous results in anesthetized animals 15 . Finally, a GPU-based image reconstruction algorithm was developed and tested with significant acceleration that allows real-time online monitoring of the pre-seizure state.…”

“…In the multi-GPU application with four GPU cards installed on the same computer, we generated four instances from the GPU-based code and ran them simultaneously. According to our previous phantom and rat experiments 15,22 , the 3D DOT reconstruction typically required 6 iterations to converge into a solution.…”

“…In our previous study with simultaneous DOT and IEEG in anesthetized rats, the pre-seizure state was investigated and uniformly identified 15 . We found that the onset of generalized seizures originates locally and early hemodynamic responses occur for several minutes before seizure onset.…”

Noninvasive High-Speed Photoacoustic Tomography of Cerebral Hemodynamics in Awake-Moving Rats

“…Other studies also reported similar positive correlation between hemodynamic signal and EEG PSD within gamma range. 35,38 DISCUSSION AND CONCLUSION We have conducted experiments based on the developed wPAT system using hyperoxia and acute PTZ-evoked seizure rat models. Results show that wPAT successfully detected cerebral HbO, HbR, and HbT changes of a rat when under hyperoxia by using 1,064, 710, and 797 nm wavelengths, respectively.…”

Localization of cortical tissue optical changes during seizure activity in vivo with optical coherence tomography

“…Optical imaging techniques such as intrinsic optical signal (IOS) [4][5][6][7], diffuse optical tomography (DOT) [8][9][10], and spatial frequency domain imaging (SFDI) [11] overcome these limitations by achieving high-resolution, minimally invasive, imaging of the occurrence and propagation of neuronal and epileptic activity through changes in intrinsic tissue optical properties.…”