1
|
Qin W, Gan Q, Yang L, Wang Y, Qi W, Ke B, Xi L. High-resolution in vivo imaging of rhesus cerebral cortex with ultrafast portable photoacoustic microscopy. Neuroimage 2021; 238:118260. [PMID: 34118393 DOI: 10.1016/j.neuroimage.2021.118260] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 06/05/2021] [Accepted: 06/08/2021] [Indexed: 02/05/2023] Open
Abstract
Revealing the structural and functional change of microvasculature is essential to match vascular response with neuronal activities in the investigation of neurovascular coupling. The increasing use of rhesus models in fundamental and clinical studies of neurovascular coupling presents an emerging need for a new imaging modality. Here we report a structural and functional cerebral vascular study of rhesus monkeys using an ultrafast, portable, and high resolution photoacoustic microscopic system with a long working distance and a special scanning mechanism to eliminate the relative displacement between the imaging interface and samples. We derived the structural and functional response of the cerebral vasculature to the alternating normoxic and hypoxic conditions by calculating the vascular diameter and functional connectivity. Both vasodilatation and vasoconstriction were observed in hypoxia. In addition to the change of vascular diameter, the decrease of functional connectivity is also an important phenomenon induced by the reduction of oxygen ventilatory. These results suggest that photoacoustic microscopy is a promising method to study the neurovascular coupling and cerebral vascular diseases due to the advanced features of high spatiotemporal resolution, excellent sensitivity to hemoglobin, and label-free imaging capability of observing hemodynamics.
Collapse
Affiliation(s)
- Wei Qin
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen 518055, Guangdong, China
| | - Qi Gan
- Department of Neurosurgery, West China Hospital Sichuan University, Chengdu 610040, Sichuan, China
| | - Lei Yang
- Department of Anesthesiology and Critical Care Medicine, West China Hospital Sichuan University, Chengdu 610040, Sichuan, China
| | - Yongchao Wang
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen 518055, Guangdong, China
| | - Weizhi Qi
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen 518055, Guangdong, China
| | - Bowen Ke
- Department of Anesthesiology and Critical Care Medicine, West China Hospital Sichuan University, Chengdu 610040, Sichuan, China.
| | - Lei Xi
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen 518055, Guangdong, China.
| |
Collapse
|
2
|
Panachakel JT, Ramakrishnan AG. Decoding Covert Speech From EEG-A Comprehensive Review. Front Neurosci 2021; 15:642251. [PMID: 33994922 PMCID: PMC8116487 DOI: 10.3389/fnins.2021.642251] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 03/18/2021] [Indexed: 11/13/2022] Open
Abstract
Over the past decade, many researchers have come up with different implementations of systems for decoding covert or imagined speech from EEG (electroencephalogram). They differ from each other in several aspects, from data acquisition to machine learning algorithms, due to which, a comparison between different implementations is often difficult. This review article puts together all the relevant works published in the last decade on decoding imagined speech from EEG into a single framework. Every important aspect of designing such a system, such as selection of words to be imagined, number of electrodes to be recorded, temporal and spatial filtering, feature extraction and classifier are reviewed. This helps a researcher to compare the relative merits and demerits of the different approaches and choose the one that is most optimal. Speech being the most natural form of communication which human beings acquire even without formal education, imagined speech is an ideal choice of prompt for evoking brain activity patterns for a BCI (brain-computer interface) system, although the research on developing real-time (online) speech imagery based BCI systems is still in its infancy. Covert speech based BCI can help people with disabilities to improve their quality of life. It can also be used for covert communication in environments that do not support vocal communication. This paper also discusses some future directions, which will aid the deployment of speech imagery based BCI for practical applications, rather than only for laboratory experiments.
Collapse
Affiliation(s)
- Jerrin Thomas Panachakel
- Medical Intelligence and Language Engineering Laboratory, Department of Electrical Engineering, Indian Institute of Science, Bangalore, India
| | | |
Collapse
|
3
|
Zhang Y, Yao L, Yang F, Yang S, Edathodathil A, Xi W, Roe AW, Li P. INS-fOCT: a label-free, all-optical method for simultaneously manipulating and mapping brain function. NEUROPHOTONICS 2020; 7:015014. [PMID: 32258220 PMCID: PMC7108754 DOI: 10.1117/1.nph.7.1.015014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 03/18/2020] [Indexed: 06/11/2023]
Abstract
Significance: Current approaches to stimulating and recording from the brain have combined electrical or optogenetic stimulation with recording approaches, such as two-photon, electrophysiology (EP), and optical intrinsic signal imaging (OISI). However, we lack a label-free, all-optical approach with high spatial and temporal resolution. Aim: To develop a label-free, all-optical method that simultaneously manipulates and images brain function using pulsed near-infrared light (INS) and functional optical coherence tomography (fOCT), respectively. Approach: We built a coregistered INS, fOCT, and OISI system. OISI and EP recordings were employed to validate the fOCT signals. Results: The fOCT signal was reliable and regional, and the area of fOCT signal corresponded with the INS-activated region. The fOCT signal was in synchrony with the INS onset time with a delay of ∼ 30 ms . The magnitude of fOCT signal exhibited a linear correlation with the INS radiant exposure. The significant correlation between the fOCT signal and INS was further supported by OISI and EP recordings. Conclusions: The proposed fiber-based, all-optical INS-fOCT method allows simultaneous stimulation and mapping without the risk of interchannel cross-talk and the requirement of contrast injection and viral transfection and offers a deep penetration depth and high resolution.
Collapse
Affiliation(s)
- Ying Zhang
- Zhejiang University, College of Optical Science and Engineering, State Key Lab of Modern Optical Instrumentation, Hangzhou, China
- Zhejiang University, Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Hangzhou, Zhejiang, China
| | - Lin Yao
- Zhejiang University, College of Optical Science and Engineering, State Key Lab of Modern Optical Instrumentation, Hangzhou, China
| | - Fen Yang
- Zhejiang University, Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Hangzhou, Zhejiang, China
| | - Shanshan Yang
- Zhejiang University, College of Optical Science and Engineering, State Key Lab of Modern Optical Instrumentation, Hangzhou, China
| | - Akshay Edathodathil
- Zhejiang University, Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Hangzhou, Zhejiang, China
| | - Wang Xi
- Zhejiang University, Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Hangzhou, Zhejiang, China
| | - Anna Wang Roe
- Zhejiang University, Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Hangzhou, Zhejiang, China
- Zhejiang University, Key Laboratory of Biomedical Engineering of Ministry of Education, Hangzhou, Zhejiang, China
- Oregon Health & Sciences University, Oregon National Primate Research Center, Division of Neuroscience, Beaverton, Oregon, United States
| | - Peng Li
- Zhejiang University, College of Optical Science and Engineering, State Key Lab of Modern Optical Instrumentation, Hangzhou, China
- Zhejiang University, International Research Center for Advanced Photonics, Hangzhou, Zhejiang, China
| |
Collapse
|
4
|
Hartmann K, Stein KP, Neyazi B, Sandalcioglu IE. First in vivo visualization of the human subarachnoid space and brain cortex via optical coherence tomography. Ther Adv Neurol Disord 2019; 12:1756286419843040. [PMID: 31447933 PMCID: PMC6689907 DOI: 10.1177/1756286419843040] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 03/10/2019] [Indexed: 11/17/2022] Open
Abstract
The present work explores optical coherence tomography (OCT) as a suitable in vivo neuroimaging modality of the subarachnoid space (SAS). Patients (n = 26) with frontolateral craniotomy were recruited. The temporal and frontal arachnoid mater and adjacent anatomical structures were scanned using microscope-integrated three-dimensional OCT, (iOCT). Analysis revealed a detailed depiction of the SAS (76.9%) with delineation of the internal microanatomical structures such as the arachnoid barrier cell membrane (ABCM; 96.2%), trabecular system (50.2%), internal blood vessels (96.2%), pia mater (26.9%) and the brain cortex (96.2%). Orthogonal distance measuring was possible. The SAS showed a mean depth of 570 µm frontotemporal. The ABCM showed a mean depth of 74 µm frontotemporal. These results indicate that OCT provides a dynamic, non-invasive tool for real-time imaging of the SAS and adjacent anatomical structures at micrometer spatial resolution. Further studies are necessary to evaluate the value of OCT during microsurgical procedures.
Collapse
Affiliation(s)
- Karl Hartmann
- Department of Neurosurgery, KRH Klinikum Nordstadt, Haltenhoffstraße 41, Hanover 30167, Germany
| | - Klaus-Peter Stein
- Department of Neurosurgery, KRH Klinikum Nordstadt, Hanover, Germany
| | - Belal Neyazi
- Department of Neurosurgery, KRH Klinikum Nordstadt, Hanover, Germany
| | | |
Collapse
|
5
|
Mokbul MI. Optical Coherence Tomography: Basic Concepts and Applications in Neuroscience Research. J Med Eng 2017; 2017:3409327. [PMID: 29214158 PMCID: PMC5682075 DOI: 10.1155/2017/3409327] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 06/22/2017] [Accepted: 09/14/2017] [Indexed: 12/28/2022] Open
Abstract
Optical coherence tomography is a micrometer-scale imaging modality that permits label-free, cross-sectional imaging of biological tissue microstructure using tissue backscattering properties. After its invention in the 1990s, OCT is now being widely used in several branches of neuroscience as well as other fields of biomedical science. This review study reports an overview of OCT's applications in several branches or subbranches of neuroscience such as neuroimaging, neurology, neurosurgery, neuropathology, and neuroembryology. This study has briefly summarized the recent applications of OCT in neuroscience research, including a comparison, and provides a discussion of the remaining challenges and opportunities in addition to future directions. The chief aim of the review study is to draw the attention of a broad neuroscience community in order to maximize the applications of OCT in other branches of neuroscience too, and the study may also serve as a benchmark for future OCT-based neuroscience research. Despite some limitations, OCT proves to be a useful imaging tool in both basic and clinical neuroscience research.
Collapse
Affiliation(s)
- Mobin Ibne Mokbul
- Notre Dame College, Motijheel Circular Road, Arambagh, Motijheel, Dhaka 1000, Bangladesh
| |
Collapse
|
6
|
Rao B, Zhang R, Li L, Shao JY, Wang LV. Photoacoustic imaging of voltage responses beyond the optical diffusion limit. Sci Rep 2017; 7:2560. [PMID: 28566693 PMCID: PMC5451395 DOI: 10.1038/s41598-017-02458-w] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 04/12/2017] [Indexed: 11/09/2022] Open
Abstract
Non-invasive optical imaging of neuronal voltage response signals in live brains is constrained in depth by the optical diffusion limit, which is due primarily to optical scattering by brain tissues. Although photoacoustic tomography breaks this limit by exciting the targets with diffused photons and detecting the resulting acoustic responses, it has not been demonstrated as a modality for imaging voltage responses. In this communication, we report the first demonstration of photoacoustic voltage response imaging in both in vitro HEK-293 cell cultures and in vivo mouse brain surfaces. Using spectroscopic photoacoustic tomography at isosbestic wavelengths, we can separate voltage response signals and hemodynamic signals on live brain surfaces. By imaging HEK-293 cell clusters through 4.5 mm thick ex vivo rat brain tissue, we demonstrate photoacoustic tomography of cell membrane voltage responses beyond the optical diffusion limit. Although the current voltage dye does not immediately allow in vivo deep brain voltage response imaging, we believe our method opens up a feasible technical path for deep brain studies in the future.
Collapse
Affiliation(s)
- Bin Rao
- Biomedical Engineering Department, Washington University of Saint Louis MO, Saint Louis, MO, 63130, USA
| | - Ruiying Zhang
- Biomedical Engineering Department, Washington University of Saint Louis MO, Saint Louis, MO, 63130, USA
| | - Lei Li
- Biomedical Engineering Department, Washington University of Saint Louis MO, Saint Louis, MO, 63130, USA
| | - Jin-Yu Shao
- Biomedical Engineering Department, Washington University of Saint Louis MO, Saint Louis, MO, 63130, USA
| | - Lihong V Wang
- Biomedical Engineering Department, Washington University of Saint Louis MO, Saint Louis, MO, 63130, USA.
| |
Collapse
|
7
|
Tong MQ, Hasan MM, Lee SS, Haque MR, Kim DH, Islam MS, Adams ME, Park BH. OCT intensity and phase fluctuations correlated with activity-dependent neuronal calcium dynamics in the Drosophila CNS [Invited]. BIOMEDICAL OPTICS EXPRESS 2017; 8:726-735. [PMID: 28270979 PMCID: PMC5330578 DOI: 10.1364/boe.8.000726] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 01/04/2017] [Accepted: 01/06/2017] [Indexed: 05/09/2023]
Abstract
Phase-resolved OCT and fluorescence microscopy were used simultaneously to examine stereotypic patterns of neural activity in the isolated Drosophila central nervous system. Both imaging modalities were focused on individually identified bursicon neurons known to be involved in a fixed action pattern initiated by ecdysis-triggering hormone. We observed clear correspondence of OCT intensity, phase fluctuations, and activity-dependent calcium-induced fluorescence.
Collapse
Affiliation(s)
- Minh Q. Tong
- Graduate Program in Neuroscience, University of California, Riverside, CA 92521, USA
| | - Md. Monirul Hasan
- Department of Bioengineering, University of California, 900 University Ave, Riverside, CA 92521, USA
| | - Sang Soo Lee
- Graduate Program in Neuroscience, University of California, Riverside, CA 92521, USA
| | - Md. Rezuanul Haque
- Department of Bioengineering, University of California, 900 University Ave, Riverside, CA 92521, USA
| | - Do-Hyoung Kim
- Department of Entomology, University of California, 900 University Ave, Riverside, CA 92521, USA
- Current Affiliation Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, South Korea
| | - Md. Shahidul Islam
- Department of Bioengineering, University of California, 900 University Ave, Riverside, CA 92521, USA
| | - Michael E. Adams
- Graduate Program in Neuroscience, University of California, Riverside, CA 92521, USA
- Department of Entomology, University of California, 900 University Ave, Riverside, CA 92521, USA
- Department of Cell Biology & Neuroscience, University of California, 900 University Ave, Riverside, CA 92521, USA
| | - B. Hyle Park
- Department of Bioengineering, University of California, 900 University Ave, Riverside, CA 92521, USA
| |
Collapse
|
8
|
High Resolution Optical Coherence Tomography for Bio-Imaging. FRONTIERS IN BIOPHOTONICS FOR TRANSLATIONAL MEDICINE 2016. [DOI: 10.1007/978-981-287-627-0_6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
|
9
|
Eberle MM, Hsu MS, Rodriguez CL, Szu JI, Oliveira MC, Binder DK, Park BH. Localization of cortical tissue optical changes during seizure activity in vivo with optical coherence tomography. BIOMEDICAL OPTICS EXPRESS 2015; 6:1812-27. [PMID: 26137382 PMCID: PMC4467710 DOI: 10.1364/boe.6.001812] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 04/10/2015] [Accepted: 04/16/2015] [Indexed: 05/02/2023]
Abstract
Optical coherence tomography (OCT) is a high resolution, minimally invasive imaging technique, which can produce depth-resolved cross-sectional images. In this study, OCT was used to detect changes in the optical properties of cortical tissue in vivo in mice during the induction of global (pentylenetetrazol) and focal (4-aminopyridine) seizures. Through the use of a confidence interval statistical method on depth-resolved volumes of attenuation coefficient, we demonstrated localization of regions exhibiting both significant positive and negative changes in attenuation coefficient, as well as differentiating between global and focal seizure propagation.
Collapse
Affiliation(s)
- Melissa M. Eberle
- Department of Bioengineering, University of California, Riverside, 900 University Ave. Riverside, CA 92521,
USA
| | - Mike S. Hsu
- Division of Biomedical Sciences, University of California, Riverside, 900 University Ave. Riverside, CA 92521,
USA
| | - Carissa L. Rodriguez
- Department of Bioengineering, University of California, Riverside, 900 University Ave. Riverside, CA 92521,
USA
| | - Jenny I. Szu
- Division of Biomedical Sciences, University of California, Riverside, 900 University Ave. Riverside, CA 92521,
USA
| | - Michael C. Oliveira
- Department of Bioengineering, University of California, Riverside, 900 University Ave. Riverside, CA 92521,
USA
| | - Devin K. Binder
- Division of Biomedical Sciences, University of California, Riverside, 900 University Ave. Riverside, CA 92521,
USA
| | - B. Hyle Park
- Department of Bioengineering, University of California, Riverside, 900 University Ave. Riverside, CA 92521,
USA
| |
Collapse
|
10
|
Wang B, Zhou J, Carney P, Jiang H. A novel detachable head-mounted device for simultaneous EEG and photoacoustic monitoring of epilepsy in freely moving rats. Neurosci Res 2015; 91:57-62. [DOI: 10.1016/j.neures.2014.08.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 07/25/2014] [Accepted: 08/13/2014] [Indexed: 02/01/2023]
|
11
|
Ramgopal S, Thome-Souza S, Jackson M, Kadish NE, Sánchez Fernández I, Klehm J, Bosl W, Reinsberger C, Schachter S, Loddenkemper T. Seizure detection, seizure prediction, and closed-loop warning systems in epilepsy. Epilepsy Behav 2014; 37:291-307. [PMID: 25174001 DOI: 10.1016/j.yebeh.2014.06.023] [Citation(s) in RCA: 211] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 06/04/2014] [Accepted: 06/10/2014] [Indexed: 12/16/2022]
Abstract
Nearly one-third of patients with epilepsy continue to have seizures despite optimal medication management. Systems employed to detect seizures may have the potential to improve outcomes in these patients by allowing more tailored therapies and might, additionally, have a role in accident and SUDEP prevention. Automated seizure detection and prediction require algorithms which employ feature computation and subsequent classification. Over the last few decades, methods have been developed to detect seizures utilizing scalp and intracranial EEG, electrocardiography, accelerometry and motion sensors, electrodermal activity, and audio/video captures. To date, it is unclear which combination of detection technologies yields the best results, and approaches may ultimately need to be individualized. This review presents an overview of seizure detection and related prediction methods and discusses their potential uses in closed-loop warning systems in epilepsy.
Collapse
Affiliation(s)
- Sriram Ramgopal
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Boston, MA, USA; Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Sigride Thome-Souza
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Boston, MA, USA; Psychiatry Department of Clinics Hospital of School of Medicine of University of Sao Paulo, Brazil
| | - Michele Jackson
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Boston, MA, USA
| | - Navah Ester Kadish
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Boston, MA, USA; Department of Neuropediatrics and Department of Medical Psychology and Medical Sociology, University Medical Center Schleswig-Holstein, Christian-Albrechts-University, Kiel, Germany
| | - Iván Sánchez Fernández
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Boston, MA, USA
| | - Jacquelyn Klehm
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Boston, MA, USA
| | - William Bosl
- Department of Health Informatics, University of San Francisco School of Nursing and Health Professions, San Francisco, CA, USA
| | - Claus Reinsberger
- Edward B. Bromfield Epilepsy Center, Dept. of Neurology, Brigham and Women's Hospital, Boston, MA, USA; Institute of Sports Medicine, Department of Exercise and Health, Faculty of Science, University of Paderborn, Germany; Institute of Sports Medicine, Faculty of Science, University of Paderborn, Warburger Str. 100, 33098 Paderborn, Germany
| | - Steven Schachter
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Tobias Loddenkemper
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Boston, MA, USA.
| |
Collapse
|
12
|
Non-invasive detection of optical changes elicited by seizure activity using time-series analysis of light scattering images in a rat model of generalized seizure. J Neurosci Methods 2014; 227:18-28. [DOI: 10.1016/j.jneumeth.2014.02.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Revised: 01/10/2014] [Accepted: 02/04/2014] [Indexed: 11/18/2022]
|
13
|
Niknazar M, Mousavi SR, Motaghi S, Dehghani A, Vosoughi Vahdat B, Shamsollahi MB, Sayyah M, Noorbakhsh SM. A unified approach for detection of induced epileptic seizures in rats using ECoG signals. Epilepsy Behav 2013; 27:355-64. [PMID: 23542539 DOI: 10.1016/j.yebeh.2013.01.028] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2012] [Revised: 01/23/2013] [Accepted: 01/29/2013] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Epileptic seizure detection is a key step for epilepsy assessment. In this work, using the pentylenetetrazole (PTZ) model, seizures were induced in rats, and ECoG signals in interictal, preictal, ictal, and postictal periods were recorded. The recorded ECoG signals were then analyzed to detect epileptic seizures in the epileptic rats. METHODS Two different approaches were considered in this work: thresholding and classification. In the thresholding approach, a feature is calculated in consecutive windows, and the resulted index is tracked over time and compared with a threshold. The moment the index crosses the threshold is considered as the moment of seizure onset. In the classification approach, features are extracted from before, during, and after ictal periods and statistically analyzed. Statistical characteristics of some features have a significant difference among these periods, thus resulting in epileptic seizure detection. RESULTS Several features were examined in the thresholding approach. Nonlinear energy and coastline features were successful in epileptic seizure detection. The best result was achieved by the coastline feature, which led to a mean of a 2-second delay in its correct detections. In the classification approach, the best result was achieved using the fuzzy similarity index that led to Pvalue<0.001. CONCLUSION This study showed that variance-based features were more appropriate for tracking abrupt changes in ECoG signals. Therefore, these features perform better in seizure onset estimation, whereas nonlinear features or indices, which are based on dynamical systems, can better track the transition of neural system to ictal period. SIGNIFICANCE This paper presents examination of different features and indices for detection of induced epileptic seizures from rat's ECoG signals.
Collapse
Affiliation(s)
- M Niknazar
- Biomedical Signal and Image Processing Laboratory (BiSIPL), School of Electrical Engineering, Sharif University of Technology, P.O. Box 11365-9363, Tehran, Iran.
| | | | | | | | | | | | | | | |
Collapse
|
14
|
Tsytsarev V, Rao B, Maslov KI, Li L, Wang LV. Photoacoustic and optical coherence tomography of epilepsy with high temporal and spatial resolution and dual optical contrasts. J Neurosci Methods 2013; 216:142-5. [PMID: 23603664 DOI: 10.1016/j.jneumeth.2013.04.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 04/01/2013] [Accepted: 04/04/2013] [Indexed: 01/26/2023]
Abstract
Epilepsy mapping with high spatial and temporal resolution has great significance for both fundamental research on epileptic neurons and the clinical management of epilepsy. In this communication, we demonstrate for the first time in vivo epilepsy mapping with high spatial and temporal resolution and dual optical contrasts in an animal model. Through the variations of a depthresolved optical coherence tomography signal with optical scattering contrast, we observed that epileptic neuron activities modulated the optical refractive index of epileptic neurons and their surrounding tissue. Simultaneously, through neurovasculature coupling mechanisms and optical absorption contrast, we used photoacoustic signals to document the hemodynamic changes of the microvasculature surrounding the epileptic neurons. The epilepsy mapping results were confirmed by a simultaneously recorded electroencephalogram signal during epileptic seizure. Our new epilepsy mapping tool, with high temporal and spatial resolution and dual optical contrasts, may find many applications, such as drug development and epilepsy surgery.
Collapse
Affiliation(s)
- Vassiliy Tsytsarev
- Optical Imaging Laboratory, Department of Biomedical Engineering, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130, USA
| | | | | | | | | |
Collapse
|