Journal articles: 'SSCEP'

1

Vulliamy, Graham, and James Carrier. "Sorcery and SSCEP: the cultural context of an educational innovation." British Journal of Sociology of Education 6, no. 1 (March 1985): 17–33. http://dx.doi.org/10.1080/0142569850060102.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Weeks, Sheldon. "Education for village life? What has happened to grade ten leavers from the five SSCEP high schools?" International Journal of Educational Development 7, no. 1 (January 1987): 33–48. http://dx.doi.org/10.1016/0738-0593(87)90005-8.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Punsawad, Yunyong, and Yodchanan Wongsawat. "Multi-command SSAEP-based BCI system with training sessions for SSVEP during an eye fatigue state." IEEJ Transactions on Electrical and Electronic Engineering 12 (June 2017): S72—S78. http://dx.doi.org/10.1002/tee.22441.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Teng, Fei, Yixin Chen, Aik Min Choong, Scott Gustafson, Christopher Reichley, Pamela Lawhead, and Dwight Waddell. "Square or Sine: Finding a Waveform with High Success Rate of Eliciting SSVEP." Computational Intelligence and Neuroscience 2011 (2011): 1–5. http://dx.doi.org/10.1155/2011/364385.

Full text

Abstract:

Steady state visual evoked potential (SSVEP) is the brain's natural electrical potential response for visual stimuli at specific frequencies. Using a visual stimulus flashing at some given frequency will entrain the SSVEP at the same frequency, thereby allowing determination of the subject's visual focus. The faster an SSVEP is identified, the higher information transmission rate the system achieves. Thus, an effective stimulus, defined as one with high success rate of eliciting SSVEP and high signal-noise ratio, is desired. Also, researchers observed that harmonic frequencies often appear in the SSVEP at a reduced magnitude. Are the harmonics in the SSVEP elicited by the fundamental stimulating frequency or by the artifacts of the stimuli? In this paper, we compare the SSVEP responses of three periodic stimuli: square wave (with different duty cycles), triangle wave, and sine wave to find an effective stimulus. We also demonstrate the connection between the strength of the harmonics in SSVEP and the type of stimulus.

APA, Harvard, Vancouver, ISO, and other styles

5

Wang, Xiaoqing. "Stochastic Separated Continuous Conic Programming: Strong Duality and a Solution Method." Mathematical Problems in Engineering 2014 (2014): 1–20. http://dx.doi.org/10.1155/2014/896591.

Full text

Abstract:

We study a new class of optimization problems calledstochastic separated continuous conic programming(SSCCP). SSCCP is an extension to the optimization model calledseparated continuous conic programming(SCCP) which has applications in robust optimization and sign-constrained linear-quadratic control. Based on the relationship among SSCCP, its dual, and their discretization counterparts, we develop a strong duality theory for the SSCCP. We also suggest a polynomial-time approximation algorithm that solves the SSCCP to any predefined accuracy.

APA, Harvard, Vancouver, ISO, and other styles

6

Chang, Min Hye, Jeong Su Lee, Jeong Heo, and Kwang Suk Park. "Eliciting dual-frequency SSVEP using a hybrid SSVEP-P300 BCI." Journal of Neuroscience Methods 258 (January 2016): 104–13. http://dx.doi.org/10.1016/j.jneumeth.2015.11.001.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Marchetti, Antonio, Fiamma Buttitta, Vittoria Carnicelli, Silvia Pellegrini, Gloria Bertacca, Giorgio Merlo, and Generoso Bevilacqua. "Enriched SSCP." Diagnostic Molecular Pathology 6, no. 4 (August 1997): 185–91. http://dx.doi.org/10.1097/00019606-199708000-00002.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Wang, Lu, Dan Han, Binbin Qian, Zhenhao Zhang, Zhijun Zhang, and Zhifang Liu. "The Validity of Steady-State Visual Evoked Potentials as Attention Tags and Input Signals: A Critical Perspective of Frequency Allocation and Number of Stimuli." Brain Sciences 10, no. 9 (September 7, 2020): 616. http://dx.doi.org/10.3390/brainsci10090616.

Full text

Abstract:

Steady-state visual evoked potential (SSVEP) is a periodic response to a repetitive visual stimulus at a specific frequency. Currently, SSVEP is widely treated as an attention tag in cognitive activities and is used as an input signal for brain–computer interfaces (BCIs). However, whether SSVEP can be used as a reliable indicator has been a controversial issue. We focused on the independence of SSVEP from frequency allocation and number of stimuli. First, a cue–target paradigm was adopted to examine the interaction between SSVEPs evoked by two stimuli with different frequency allocations under different attention conditions. Second, we explored whether signal strength and the performance of SSVEP-based BCIs were affected by the number of stimuli. The results revealed that no significant interaction of SSVEP responses appeared between attended and unattended stimuli under various frequency allocations, regardless of their appearance in the fundamental or second-order harmonic. The amplitude of SSVEP suffered no significant gain or loss under different numbers of stimuli, but the performance of SSVEP-based BCIs varied along with duration of stimuli; that is, the recognition rate was not affected by the number of stimuli when the duration of stimuli was long enough, while the information transfer rate (ITR) presented the opposite trend. It can be concluded that SSVEP is a reliable tool for marking and monitoring multiple stimuli simultaneously in cognitive studies, but much caution should be taken when choosing a suitable duration and the number of stimuli, in order to achieve optimal utility of BCIs in the future.

APA, Harvard, Vancouver, ISO, and other styles

9

Zhu, Fangkun, Lu Jiang, Guoya Dong, Xiaorong Gao, and Yijun Wang. "An Open Dataset for Wearable SSVEP-Based Brain-Computer Interfaces." Sensors 21, no. 4 (February 10, 2021): 1256. http://dx.doi.org/10.3390/s21041256.

Full text

Abstract:

Brain-computer interfaces (BCIs) provide humans a new communication channel by encoding and decoding brain activities. Steady-state visual evoked potential (SSVEP)-based BCI stands out among many BCI paradigms because of its non-invasiveness, little user training, and high information transfer rate (ITR). However, the use of conductive gel and bulky hardware in the traditional Electroencephalogram (EEG) method hinder the application of SSVEP-based BCIs. Besides, continuous visual stimulation in long time use will lead to visual fatigue and pose a new challenge to the practical application. This study provides an open dataset, which is collected based on a wearable SSVEP-based BCI system, and comprehensively compares the SSVEP data obtained by wet and dry electrodes. The dataset consists of 8-channel EEG data from 102 healthy subjects performing a 12-target SSVEP-based BCI task. For each subject, 10 consecutive blocks were recorded using wet and dry electrodes, respectively. The dataset can be used to investigate the performance of wet and dry electrodes in SSVEP-based BCIs. Besides, the dataset provides sufficient data for developing new target identification algorithms to improve the performance of wearable SSVEP-based BCIs.

APA, Harvard, Vancouver, ISO, and other styles

10

Chen, Yeou-Jiunn, Pei-Chung Chen, Shih-Chung Chen, and Chung-Min Wu. "Denoising Autoencoder-Based Feature Extraction to Robust SSVEP-Based BCIs." Sensors 21, no. 15 (July 23, 2021): 5019. http://dx.doi.org/10.3390/s21155019.

Full text

Abstract:

For subjects with amyotrophic lateral sclerosis (ALS), the verbal and nonverbal communication is greatly impaired. Steady state visually evoked potential (SSVEP)-based brain computer interfaces (BCIs) is one of successful alternative augmentative communications to help subjects with ALS communicate with others or devices. For practical applications, the performance of SSVEP-based BCIs is severely reduced by the effects of noises. Therefore, developing robust SSVEP-based BCIs is very important to help subjects communicate with others or devices. In this study, a noise suppression-based feature extraction and deep neural network are proposed to develop a robust SSVEP-based BCI. To suppress the effects of noises, a denoising autoencoder is proposed to extract the denoising features. To obtain an acceptable recognition result for practical applications, the deep neural network is used to find the decision results of SSVEP-based BCIs. The experimental results showed that the proposed approaches can effectively suppress the effects of noises and the performance of SSVEP-based BCIs can be greatly improved. Besides, the deep neural network outperforms other approaches. Therefore, the proposed robust SSVEP-based BCI is very useful for practical applications.

APA, Harvard, Vancouver, ISO, and other styles

11

Pillai, Jain Bhaskara, Yonni Pellet, Georgia Panagopoulos, Mostafa A. Sadek, Djamila Abjigitova, David Weiss, and Konstadinos A. Plestis. "Somatosensory-Evoked Potential–Guided Intercostal Artery Reimplantation in Thoracoabdominal Aortic Aneurysm Surgery." Innovations: Technology and Techniques in Cardiothoracic and Vascular Surgery 8, no. 4 (June 2013): 302–6. http://dx.doi.org/10.1097/imi.0000000000000005.

Full text

Abstract:

Objective This study was undertaken to evaluate the use of somatosensory-evokedpotential (SSEP) monitoring on intercostal artery reimplantation (IAR) and spinal cord ischemia rates during thoracoabdominal ortic aneurysm repair. Methods Fifty-two patients had thoracoabdominal aortic aneurysm repair with IAR under SSEP guidance and 79 patients had repair with routine IAR without SSEP guidance from 1999 to 2010. Results No differences were observed between the two groups in age (63.1 ± 11.6 vs 64.8 ± 9.8 years), sex (57.7% vs 50.6% men), chronic dissections (40.4% vs 44.3%), renal insufficiency (11.5% vs 10.1%), and Crawford type 1 and 2 aneurysms (53.9% vs 53.9%). There was one case (1.9%) of immediate paraplegia and one case (1.9%) of delayed paraplegia in the SSEP group versus 2 cases (2.5%) of immediate paraplegia in the non-SSEP group ( P = 0.92). In the SSEP group, 38 patients (73.1%) had SSEP changes, but only 15 (28.8%) required reimplantation. There were fewer IARs in the SSEP group compared with the non-SSEP group (28.8% vs. 59.5%, P = 0.004). No difference was observed in 30-day mortality between the SSEP and the non-SSEP group (3.9% vs. 7.6%, P = 0.48). Conclusions The use of SSEP monitoring led to a significant decrease in the need for IAR without increasing the paraplegia rate.

APA, Harvard, Vancouver, ISO, and other styles

12

Zhang, Feng, Chengcheng Han, Lili Li, Xin Zhang, Jun Xie, and Yeping Li. "Research on High-Frequency Combination Coding-Based SSVEP-BCIs and Its Signal Processing Algorithms." Shock and Vibration 2015 (2015): 1–12. http://dx.doi.org/10.1155/2015/194230.

Full text

Abstract:

This study presents a new steady-state visual evoked potential (SSVEP) paradigm for brain computer interface (BCI) systems. The new paradigm is High-Frequency Combination Coding-Based SSVEP (HFCC-SSVEP). The goal of this study is to increase the number of targets using fewer stimulation frequencies, with diminishing subject’s fatigue and reducing the risk of photosensitive epileptic seizures. This paper investigated the HFCC-SSVEP high-frequency response (beyond 25 Hz) for 3 frequencies (25 Hz, 33.33 Hz, and 40 Hz). HFCC-SSVEP producesnnwithnhigh stimulation frequencies through Time Series Combination Code. Furthermore, The Improved Hilbert-Huang Transform (IHHT) is adopted to extract time-frequency feature of the proposed SSVEP response. Lastly, the differentiation combination (DC) method is proposed to select the combination coding sequence in order to increase the recognition rate; as a result, IHHT algorithm and DC method for the proposed SSVEP paradigm in this study increase recognition efficiency so as to improve ITR and increase the stability of the BCI system. Furthermore, SSVEPs evoked by high-frequency stimuli (beyond 25 Hz) minimally diminish subject’s fatigue and prevent safety hazards linked to photo-induced epileptic seizures. This study tests five subjects in order to verify the feasibility of the proposed method.

APA, Harvard, Vancouver, ISO, and other styles

13

Li, Minglun, Dianning He, Chen Li, and Shouliang Qi. "Brain–Computer Interface Speller Based on Steady-State Visual Evoked Potential: A Review Focusing on the Stimulus Paradigm and Performance." Brain Sciences 11, no. 4 (April 1, 2021): 450. http://dx.doi.org/10.3390/brainsci11040450.

Full text

Abstract:

The steady-state visual evoked potential (SSVEP), measured by the electroencephalograph (EEG), has high rates of information transfer and signal-to-noise ratio, and has been used to construct brain–computer interface (BCI) spellers. In BCI spellers, the targets of alphanumeric characters are assigned different visual stimuli and the fixation of each target generates a unique SSVEP. Matching the SSVEP to the stimulus allows users to select target letters and numbers. Many BCI spellers that harness the SSVEP have been proposed over the past two decades. Various paradigms of visual stimuli, including the procedure of target selection, layout of targets, stimulus encoding, and the combination with other triggering methods are used and considered to influence on the BCI speller performance significantly. This paper reviews these stimulus paradigms and analyzes factors influencing their performance. The fundamentals of BCI spellers are first briefly described. SSVEP-based BCI spellers, where only the SSVEP is used, are classified by stimulus paradigms and described in chronological order. Furthermore, hybrid spellers that involve the use of the SSVEP are presented in parallel. Factors influencing the performance and visual fatigue of BCI spellers are provided. Finally, prevailing challenges and prospective research directions are discussed to promote the development of BCI spellers.

APA, Harvard, Vancouver, ISO, and other styles

14

Lee, Hyeon Kyu, and Young-Seok Choi. "Enhancing SSVEP-Based Brain-Computer Interface with Two-Step Task-Related Component Analysis." Sensors 21, no. 4 (February 12, 2021): 1315. http://dx.doi.org/10.3390/s21041315.

Full text

Abstract:

Among various methods for frequency recognition of the steady-state visual evoked potential (SSVEP)-based brain-computer interface (BCI) study, a task-related component analysis (TRCA), which extracts discriminative spatial filters for classifying electroencephalogram (EEG) signals, has gathered much interest. The TRCA-based SSVEP method yields lower computational cost and higher classification performance compared to existing SSVEP methods. In spite of its utility, the TRCA-based SSVEP method still suffers from the degradation of the frequency recognition rate in cases where EEG signals with a short length window are used. To address this issue, here, we propose an improved strategy for decoding SSVEPs, which is insensitive to a window length by carrying out two-step TRCA. The proposed method reuses the spatial filters corresponding to target frequencies generated by the TRCA. Followingly, the proposed method accentuates features for target frequencies by correlating individual template and test data. For the evaluation of the performance of the proposed method, we used a benchmark dataset with 35 subjects and confirmed significantly improved performance comparing with other existing SSVEP methods. These results imply the suitability as an efficient frequency recognition strategy for SSVEP-based BCI applications.

APA, Harvard, Vancouver, ISO, and other styles

15

Phillips, Jessica L. H., Nohra Chalouhi, Pascal Jabbour, Robert M. Starke, Cory D. Bovenzi, Robert H. Rosenwasser, W. Bryan Wilent, Victor M. Romo, and Stavropoula I. Tjoumakaris. "Somatosensory Evoked Potential Changes in Neuroendovascular Procedures." Neurosurgery 75, no. 5 (July 18, 2014): 560–67. http://dx.doi.org/10.1227/neu.0000000000000510.

Full text

Abstract:

Abstract BACKGROUND: Neurophysiological monitoring is routinely used during neurosurgical procedures. Use of neurophysiological monitoring has extended to neuroendovascular procedures, but evidence of its impact on clinical outcome in this arena is limited. OBJECTIVE: To report the incidence of significant intraoperative somatosensory evoked potential (SSEP) changes during neuroendovascular surgery and to correlate SSEP changes with clinical outcomes. METHODS: Patients who underwent neuroendovascular surgery at our institution between 2011 and 2013 were included in the analysis. Medical charts and imaging studies were reviewed retrospectively for sex, age, lesion type and size, clinical presentation, type of endovascular procedure, duration of SSEP change, reversibility of SSEP change, incidence of intraoperative complications and related mortalities, presence of new infarction within 72 hours of intervention, and discharge outcome. RESULTS: Of 873 consecutive patients, 52 (6%) had clinically significant intraoperative SSEP changes. Twenty-four patients (46%) had SSEP changes that were corrected, and 28 patients (54%) had changes that were not reversed before the end of surgery. Both decreased duration and reversal of SSEP changes were associated with a lower incidence of postoperative infarction and more favorable clinical outcome on discharge. The positive predictive value of an irreversible SSEP change for postoperative infarction in our study was 21%, and the negative predictive value was 83%. CONCLUSION: The approximate incidence of SSEP changes is 6% during neuroendovascular procedures. Rapid reversal of SSEP changes is associated with better outcomes. SSEP monitoring may be a valuable tool for preventing complications after neuroendovascular interventions.

APA, Harvard, Vancouver, ISO, and other styles

16

Zhu, Danhua, Jordi Bieger, Gary Garcia Molina, and Ronald M. Aarts. "A Survey of Stimulation Methods Used in SSVEP-Based BCIs." Computational Intelligence and Neuroscience 2010 (2010): 1–12. http://dx.doi.org/10.1155/2010/702357.

Full text

Abstract:

Brain-computer interface (BCI) systems based on the steady-state visual evoked potential (SSVEP) provide higher information throughput and require shorter training than BCI systems using other brain signals. To elicit an SSVEP, a repetitive visual stimulus (RVS) has to be presented to the user. The RVS can be rendered on a computer screen by alternating graphical patterns, or with external light sources able to emit modulated light. The properties of an RVS (e.g., frequency, color) depend on the rendering device and influence the SSVEP characteristics. This affects the BCI information throughput and the levels of user safety and comfort. Literature on SSVEP-based BCIs does not generally provide reasons for the selection of the used rendering devices or RVS properties. In this paper, we review the literature on SSVEP-based BCIs and comprehensively report on the different RVS choices in terms of rendering devices, properties, and their potential influence on BCI performance, user safety and comfort.

APA, Harvard, Vancouver, ISO, and other styles

17

Touyama, Hideaki, and Mitsuru Sakuda. "Online Control of a Virtual Object with Collaborative SSVEP." Journal of Advanced Computational Intelligence and Intelligent Informatics 21, no. 7 (November 20, 2017): 1291–97. http://dx.doi.org/10.20965/jaciii.2017.p1291.

Full text

Abstract:

In this paper, we propose a brain-computer interface (BCI) based on collaborative steady-state visually evoked potential (SSVEP). A technique for estimating the common direction of the gaze of multiple subjects is studied with a view to controlling a virtual object in a virtual environment. The electro-encephalograms (EEG) of eight volunteers are simultaneously recorded with two virtual cubes as visual stimuli. These two virtual cubes flicker at different rates, 6 Hz and 8 Hz, and the corresponding SSVEP is observed around the occipital area. The amplitude spectra of the EEG activity of individual subjects are analyzed, averaged, and synthesized to obtain the collaborative SSVEP. Machine learning is applied to estimate the common gaze direction of the eight subjects with the supervised data from fewer than eight subjects. The estimation accuracy is perfect only in the case of the collaborative SSVEP. One-dimensional control of a virtual ball is performed by controlling the common eye gaze direction, which induces the collaborative SSVEP.

APA, Harvard, Vancouver, ISO, and other styles

18

Xie, Songyun, Chang Liu, Klaus Obermayer, Fangshi Zhu, Linan Wang, Xinzhou Xie, and Wei Wang. "Stimulator Selection in SSVEP-Based Spatial Selective Attention Study." Computational Intelligence and Neuroscience 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/6410718.

Full text

Abstract:

Steady-State Visual Evoked Potentials (SSVEPs) are widely used in spatial selective attention. In this process the two kinds of visual simulators, Light Emitting Diode (LED) and Liquid Crystal Display (LCD), are commonly used to evoke SSVEP. In this paper, the differences of SSVEP caused by these two stimulators in the study of spatial selective attention were investigated. Results indicated that LED could stimulate strong SSVEP component on occipital lobe, and the frequency of evoked SSVEP had high precision and wide range as compared to LCD. Moreover a significant difference between noticed and unnoticed frequencies in spectrum was observed whereas in LCD mode this difference was limited and selectable frequencies were also limited. Our experimental finding suggested that average classification accuracies among all the test subjects in our experiments were 0.938 and 0.853 in LED and LCD mode, respectively. These results indicate that LED simulator is appropriate for evoking the SSVEP for the study of spatial selective attention.

APA, Harvard, Vancouver, ISO, and other styles

19

Mouli, Surej, Ramaswamy Palaniappan, Emmanuel Molefi, and Ian McLoughlin. "In-Ear Electrode EEG for Practical SSVEP BCI." Technologies 8, no. 4 (November 5, 2020): 63. http://dx.doi.org/10.3390/technologies8040063.

Full text

Abstract:

Steady State Visual Evoked Potential (SSVEP) methods for brain–computer interfaces (BCI) are popular due to higher information transfer rate and easier setup with minimal training, compared to alternative methods. With precisely generated visual stimulus frequency, it is possible to translate brain signals into external actions or signals. Traditionally, SSVEP data is collected from the occipital region using electrodes with or without gel, normally mounted on a head cap. In this experimental study, we develop an in-ear electrode to collect SSVEP data for four different flicker frequencies and compare against occipital scalp electrode data. Data from five participants demonstrates the feasibility of in-ear electrode based SSVEP, significantly enhancing the practicability of wearable BCI applications.

APA, Harvard, Vancouver, ISO, and other styles

20

Yue, Qing, Tyson Hale, and Aaron Knecht. "A Comparison of Interside Asymmetries of Lower Extremity Somatosensory Evoked Potentials in Anesthetized Patients with Unilateral Lumbosacral Radiculopathy." Asian Spine Journal 11, no. 1 (February 28, 2017): 99–104. http://dx.doi.org/10.4184/asj.2017.11.1.99.

Full text

Abstract:

<sec><title>Study Design</title>Prospective cohort study.</sec><sec><title>Purpose</title>This study was to investigate interside asymmetries of three lower extremity somatosensory evoked potentials (SSEPs) in anesthetized patients with unilateral lumbosacral radiculopathy.</sec><sec><title>Overview of Literature</title>Although interside asymmetry is an established criterion of abnormal SSEP, little is known which of the lower SSEPs is more sensitive in detecting interside asymmetry in anesthetized patients.</sec><sec><title>Methods</title>Superficial peroneal nerve SSEP (SPN-SSEP), posterior tibial nerve SSEP (PTN-SSEP), and sural nerve SSEP were obtained in 31 lumbosacral surgery patients with unilateral lumbosacral radiculopathy, and compared with a group of 22 control subjects.</sec><sec><title>Results</title>The lumbosacral group showed significant larger interside asymmetry ratios of P37 latencies in SPN-SSEP and PTN-SSEP, and significant larger interside asymmetry ratio of P37-N45 amplitude in SPN-SSEP, when comparing with the control group. Within the lumbosacral group but not the control group, SPN-SSEP displayed significant larger interside asymmetry ratio in P37 latency. When referencing to the control group, more patients in the lumbosacral group displayed abnormal interside SPN-SSEP latency asymmetrieswhich corroborated the symptom laterality.</sec><sec><title>Conclusions</title>The data suggested that SPN-SSEP was more sensitive in detecting interside latency asymmetry in anesthetized patients.</sec>

APA, Harvard, Vancouver, ISO, and other styles

21

Brinkmann, Nicole, Rainer Martens, and Christoph C. Tebbe. "Origin and Diversity of Metabolically Active Gut Bacteria from Laboratory-Bred Larvae of Manduca sexta (Sphingidae, Lepidoptera, Insecta)." Applied and Environmental Microbiology 74, no. 23 (October 10, 2008): 7189–96. http://dx.doi.org/10.1128/aem.01464-08.

Full text

Abstract:

ABSTRACT Cultivation-independent analyses based on genetic profiling of partial bacterial 16S rRNA genes by PCR-single-strand conformation polymorphism (PCR-SSCP), reverse transcriptase (RT)-PCR-SSCP of the 16S rRNA itself, and stable isotope probing (SIP), followed by RT-PCR-SSCP, were applied to characterize the diversity of metabolically active bacteria in the larval gut of Manduca sexta bred on tobacco leaves under greenhouse conditions. For SIP, hatching larvae were fed with leaves from tobacco plants grown in a 13CO2-enriched atmosphere. Dominant SSCP bands were sequenced and phylogenetically analyzed. Only one major gut colonizer, an Enterococcus relative, was detected; it occurred in the heavy RNA fraction, demonstrating its metabolic activity, and it originated from eggs, where its metabolic activity was also indicated by rRNA-based SSCP profiles. In contrast, a Citrobacter sedlakii relative was detected on eggs by DNA-SSCP, but rRNA-SSCP and SIP-rRNA-SSCP were negative, suggesting that these bacterial cells were inactive. A Burkholderia relative was dominant and metabolically active on the tobacco leaves but inactive inside the gut, where it was also quantitatively reduced, as suggested by lower band intensities in the DNA-based SSCP profiles. SIP-RNA-SSCP detected another metabolically active gut bacterium (Enterobacter sp.) and more bacteria in the light RNA fraction, indicating low or no metabolic activity of the latter inside the gut. We conclude that the larval gut supported only a low diversity of metabolically active bacteria.

APA, Harvard, Vancouver, ISO, and other styles

22

Farrow, Maree, Richard B. Silberstein, Florence Levy, Andrew Pipingas, Katie Wood, David A. Hay, and Frederick C. Jarman. "Prefrontal and Parietal Deficits in ADHD Suggested by Brain Electrical Activity Mapping During Children's Performance of the AX CPT." Australian Educational and Developmental Psychologist 13, no. 1 (May 1996): 59–68. http://dx.doi.org/10.1017/s0816512200027413.

Full text

Abstract:

AbstractNine children meeting DSM-III-R criteria for Attention Deficit Hyperactivity Disorder (ADHD) and eighteen normal children participated in this study. A screening assessment revealed significantly more behavioural and academic problems in the ADHD group. Subjects performed a low demand visual vigilance task (the reference task) and the AX version of the continuous perfonnance task (CPT), while the steady-state visually evoked potential (SSVEP) was continuously recorded from 64 scalp electrode sites. The topography of the SSVEP amplitude difference between the reference and AX tasks was examined. In the 3.5 second interval between the appearances of the “A” and the “X” normal children showed transient reductions in right prefrontal SSVEP amplitude and a sustained reduction in right parieto-occipital SSVEP amplitude. These reductions in SSVEP amplitude were not seen in ADHD subjects. These results suggest that the presentation of a priming stimulus is associated with increased activation of right prefrontal and parieto-occipital regions in normal children, whereas the absence of this pattern of activation suggests a deficit in these processes in ADHD.

APA, Harvard, Vancouver, ISO, and other styles

23

Fung, N. Y., Y. Hu, M. G. Irwin, B. F. M. Chow, and M. Y. Yuen. "Comparison between Sevoflurane/Remifentanil and Propofol/Remifentanil Anaesthesia in Providing Conditions for Somatosensory Evoked Potential Monitoring during Scoliosis Corrective Surgery." Anaesthesia and Intensive Care 36, no. 6 (November 2008): 779–85. http://dx.doi.org/10.1177/0310057x0803600605.

Full text

Abstract:

Somatosensory evoked potential (SSEP) monitoring is an important tool in spinal corrective surgery. Anaesthesia has a significant influence on SSEP monitoring and a technique which has the least and shortest suppressant effect on SSEP while facilitating a fast recovery from anaesthesia is ideal. We compared the effect of sevoflurane/remifentanil and propofol/remifentanil anaesthesia on SSEPs during scoliosis corrective surgery and assessed patients’ clinical recovery profiles. Twenty patients with idiopathic scoliosis receiving surgical correction with intraoperative SSEP monitoring were prospectively randomised to receive sevoflurane/remifentanil anaesthesia or propofol/remifentanil anaesthesia. During surgery, changes in anaesthesia dose and physiological variables were recorded, while SSEP was continuously monitored. A simulated ‘wake-up’ test was performed postoperatively to assess speed and quality of recovery from anaesthesia. The effects of propofol and sevoflurane resulted in SSEP amplitude variability between 18.0% ± 3.5% to 28.7% ± 5.9% and SSEP latency variability within 1.3% ± 0.4% to 2.6% ± 1.2%. Patients receiving sevoflurane had faster suppression and faster recovery of SSEP amplitude compared to propofol (P <0.05), although propofol anaesthesia showed less within-patient variability in Cz amplitude and latency (P <0.05). On cessation of anaesthesia, time to eye-opening (5.2 vs. 16.5 minutes) and toe movement (5.4 vs. 17.4 minutes) was shorter following sevoflurane (all P <0.05). These findings indicate that propofol produces a better SSEP signal than sevoflurane. However, adjustments in sevoflurane concentration result in faster changes in the SSEP signal than propofol. Assessment of neurological function was facilitated more rapidly after sevoflurane anaesthesia.

APA, Harvard, Vancouver, ISO, and other styles

24

Ares, William J., Ramesh M. Grandhi, David M. Panczykowski, Gregory M. Weiner, Parthasarathy Thirumala, Miguel E. Habeych, Donald J. Crammond, et al. "Diagnostic Accuracy of Somatosensory Evoked Potential Monitoring in Evaluating Neurological Complications During Endovascular Aneurysm Treatment." Operative Neurosurgery 14, no. 2 (June 14, 2017): 151–57. http://dx.doi.org/10.1093/ons/opx104.

Full text

Abstract:

Abstract BACKGROUND Somatosensory evoked potential (SSEP) monitoring is used extensively for early detection and prevention of neurological complications in patients undergoing many different neurosurgical procedures. However, the predictive ability of SSEP monitoring during endovascular treatment of cerebral aneurysms is not well detailed. OBJECTIVE To evaluate the performance of intraoperative SSEP in the prediction postprocedural neurological deficits (PPNDs) after coil embolization of intracranial aneurysms. METHODS This population-based cohort study included patients ≥18 years of age undergoing intracranial aneurysm embolization with concurrent SSEP monitoring between January 2006 and August 2012. The ability of SSEP to predict PPNDs was analyzed by multiple regression analyses and assessed by the area under the receiver operating characteristic curve. RESULTS In a population of 888 patients, SSEP changes occurred in 8.6% (n = 77). Twenty-eight patients (3.1%) suffered PPNDs. A 50% to 99% loss in SSEP waveform was associated with a 20-fold increase in risk of PPND; a total loss of SSEP waveform, regardless of permanence, was associated with a greater than 200-fold risk of PPND. SSEPs displayed very good predictive ability for PPND, with an area under the receiver operating characteristic curve of 0.84 (95% CI 0.76-0.92). CONCLUSION This study supports the predictive ability of SSEPs for the detection of PPNDs. The magnitude and persistence of SSEP changes is clearly associated with the development of PPNDs. The utility of SSEP monitoring in detecting ischemia may provide an opportunity for neurointerventionalists to respond to changes intraoperatively to mitigate the potential for PPNDs.

APA, Harvard, Vancouver, ISO, and other styles

25

WAGNER, MARTIN, ANGELIKA LEHNER, DIETER KLEIN, and ANDREAS BUBERT. "Single-Strand Conformation Polymorphisms in the hly Gene and Polymerase Chain Reaction Analysis of a Repeat Region in the iap Gene to Identify and Type Listeria monocytogenes." Journal of Food Protection 63, no. 3 (March 1, 2000): 332–36. http://dx.doi.org/10.4315/0362-028x-63.3.332.

Full text

Abstract:

Two novel methods that allow the powerful identification of Listeria monocytogenes by polymerase chain reaction (PCR) and simultaneous differentiation by special electrophoresis formats are described. The first method involves a PCR-driven single-strand conformation polymorphism (SSCP-PCR) assay using a portion of the noncoding region of the hly gene. The assay was evaluated with 120 genetically distinct L. monocytogenes strains of either foodborne or clinical origin. Distribution of listerial strains to at least 14 SSCP types was observed. In respect to the panel of strains, 39.7% were assigned to SSCP type 3, and 19% showed SSCP type 5. Further, SSCP type 1 was found in 7.5% of all strains, SSCP type 10 in 6.7%, and 5.8% each for SSCP types 6 and 7. The SSCP types 4, 9, and 11 were infrequently described in 2.55%, 3.3%, and 4.2%, respectively, of all isolates. At least 0.85% represented each of the SSCP types 2, 13, and 14, and 1.7% displayed SSCP types 8 and 12. In the second method, the internal threonine-asparagine repeat portion of the L. monocytogenes p60 protein was used for setting up a PCR-based identification and parallel differentiation assay. Ten different repeat types (RTs), according to different sizes of PCR products, were observed. Of 163 strains tested, 35.58% of samples were assigned to RT 1, 39.26% to RT 2, 3.68% to RT 3, 6.13% to RT 4, 4.29% to RT 5, 2.45% to RT 6, 5.52% to RT 7, 0.61% to RT 8, 0.61% to RT 9, and 1.83% to RT 10. The data suggest that both methods allow the simple identification and differentiation of L. monocytogenes isolates. Therefore, both the SSCP-PCR and the PCR-based identification and parallel differentiation assay could represent single-strand pretyping assays before laborious reference typing methods are applied.

APA, Harvard, Vancouver, ISO, and other styles

26

Peng, Zai-Yun, Jing-Jing Wang, Xian-Jun Long, and Fu-Ping Liu. "Painlevé–Kuratowski Convergence of Solutions for Perturbed Symmetric Set-Valued Quasi-Equilibrium Problem via Improvement Sets." Asia-Pacific Journal of Operational Research 37, no. 04 (July 24, 2020): 2040003. http://dx.doi.org/10.1142/s0217595920400035.

Full text

Abstract:

This paper is devoted to study the Painlevé–Kuratowski convergence of solution sets for perturbed symmetric set-valued quasi-equilibrium problems (SSQEP)[Formula: see text] via improvement sets. By virtue of the oriented distance function, the sufficient conditions of Painlevé–Kuratowski convergence of efficient solution sets for (SSQEP)[Formula: see text] are obtained through a new nonlinear scalarization technical. Then, under [Formula: see text]-convergence of set-valued mappings, the Painlevé–Kuratowski convergence of weak efficient solution sets for (SSQEP)[Formula: see text] is discussed. What’s more, with suitable convergence assumptions, we also establish the sufficient conditions of lower Painlevé–Kuratowski convergence of Borwein proper efficient solution sets for (SSQEP)[Formula: see text] under improvement sets. Some interesting examples are formulated to illustrate the significance of the main results.

APA, Harvard, Vancouver, ISO, and other styles

27

Cao, Fei, Huashan Li, Yang Zhang, and Liang Zhao. "Numerical Simulation and Comparison of Conventional and Sloped Solar Chimney Power Plants: The Case for Lanzhou." Scientific World Journal 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/852864.

Full text

Abstract:

The solar chimney power plant (SCPP) generates updraft wind through the green house effect. In this paper, the performances of two SCPP styles, that is, the conventional solar chimney power plant (CSCPP) and the sloped solar chimney power plant (SSCPP), are compared through a numerical simulation. A simplified Computational Fluid Dynamics (CFD) model is built to predict the performances of the SCPP. The model is validated through a comparison with the reported results from the Manzanares prototype. The annual performances of the CSCPP and the SSCPP are compared by taking Lanzhou as a case study. Numerical results indicate that the SSCPP holds a higher efficiency and generates smoother power than those of the CSCPP, and the effective pressure in the SSCPP is relevant to both the chimney and the collector heights.

APA, Harvard, Vancouver, ISO, and other styles

28

Ikeda, Akira, and Yoshikazu Washizawa. "Steady-State Visual Evoked Potential Classification Using Complex Valued Convolutional Neural Networks." Sensors 21, no. 16 (August 6, 2021): 5309. http://dx.doi.org/10.3390/s21165309.

Full text

Abstract:

The steady-state visual evoked potential (SSVEP), which is a kind of event-related potential in electroencephalograms (EEGs), has been applied to brain–computer interfaces (BCIs). SSVEP-based BCIs currently perform the best in terms of information transfer rate (ITR) among various BCI implementation methods. Canonical component analysis (CCA) or spectrum estimation, such as the Fourier transform, and their extensions have been used to extract features of SSVEPs. However, these signal extraction methods have a limitation in the available stimulation frequency; thus, the number of commands is limited. In this paper, we propose a complex valued convolutional neural network (CVCNN) to overcome the limitation of SSVEP-based BCIs. The experimental results demonstrate that the proposed method overcomes the limitation of the stimulation frequency, and it outperforms conventional SSVEP feature extraction methods.

APA, Harvard, Vancouver, ISO, and other styles

29

Silberstein, R. B., A. Pipingas, J. Song, D. A. Camfield, P. J. Nathan, and C. Stough. "Examining Brain-Cognition Effects of Ginkgo Biloba Extract: Brain Activation in the Left Temporal and Left Prefrontal Cortex in an Object Working Memory Task." Evidence-Based Complementary and Alternative Medicine 2011 (2011): 1–10. http://dx.doi.org/10.1155/2011/164139.

Full text

Abstract:

Ginkgo Biloba extract (GBE) is increasingly used to alleviate symptoms of age related cognitive impairment, with preclinical evidence pointing to a pro-cholinergic effect. While a number of behavioral studies have reported improvements to working memory (WM) associated with GBE, electrophysiological studies of GBE have typically been limited to recordings during a resting state. The current study investigated the chronic effects of GBE on steady state visually evoked potential (SSVEP) topography in nineteen healthy middle-aged (50-61 year old) male participants whilst completing an object WM task. A randomized double-blind crossover design was employed in which participants were allocated to receive 14 days GBE and 14 days placebo in random order. For both groups, SSVEP was recorded from 64 scalp electrode sites during the completion of an object WM task both pre- and 14 days post-treatment. GBE was found to improve behavioural performance on the WM task. GBE was also found to increase the SSVEP amplitude at occipital and frontal sites and increase SSVEP latency at left temporal and left frontal sites during the hold component of the WM task. These SSVEP changes associated with GBE may represent more efficient processing during WM task completion.

APA, Harvard, Vancouver, ISO, and other styles

30

Bian, Li Hong, and Ya Jun Lang. "Application of PCR-SSCP Technology in Microorganism Detection." Advanced Materials Research 1044-1045 (October 2014): 716–19. http://dx.doi.org/10.4028/www.scientific.net/amr.1044-1045.716.

Full text

Abstract:

PCR-SSCP is a technology based on the combination of PCR and SSCP, widely used in such research fields as microorganism identification and microorganism flora. In this paper, the application of PCR-SSCP in bacterial detection and microbial community monitoring is briefly introduced.

APA, Harvard, Vancouver, ISO, and other styles

31

Xie, Jiahua, Todd C. Wehner, and Mark A. Conkling. "PCR-based Single-strand Conformation Polymorphism (SSCP) Analysis to Clone Nine Aquaporin Genes in Cucumber." Journal of the American Society for Horticultural Science 127, no. 6 (November 2002): 925–30. http://dx.doi.org/10.21273/jashs.127.6.925.

Full text

Abstract:

Combining the use of PCR and single-strand conformation polymorphisms (SSCP), nine sequences from the cucumber genome were successfully identified and cloned that encoded two well-conserved asparagine-proline-alanine (NPA) domain homologues to aquaporin genes. The sensitivity and detection efficiency of SSCP and restriction enzyme analysis for detecting DNA sequence variation were evaluated using similar-sized DNA fragments. The SSCP analysis was more sensitive and efficient for discriminating different clones than restriction enzyme analysis, although some sequence variation inside similar-sized DNA fragments could be identified by restriction analysis. Consideration of the results of SSCP analysis with DNA sequence information indicated that one or two base pair changes in the amplified regions could be detected. Moreover, the SSCP analysis results of genomic DNA PCR products that were amplified by degenerate primers can provide rough information about the number of member genes. If the SSCP bands of a cloned fragment (such as CRB7) did not have the corresponding bands from genomic DNA PCR products, that fragment might be a misamplified product. The PCR-based SSCP method with degenerate oligonucleotide primers should facilitate the cloning of member genes.

APA, Harvard, Vancouver, ISO, and other styles

32

Kashiwase, Yoshiyuki, Kazumichi Matsumiya, Ichiro Kuriki, and Satoshi Shioiri. "Time Courses of Attentional Modulation in Neural Amplification and Synchronization Measured with Steady-state Visual-evoked Potentials." Journal of Cognitive Neuroscience 24, no. 8 (August 2012): 1779–93. http://dx.doi.org/10.1162/jocn_a_00212.

Full text

Abstract:

Endogenous attention modulates the amplitude and phase coherence of steady-state visual-evoked potentials (SSVEPs). In efforts to decipher the neural mechanisms of attentional modulation, we compared the time course of attentional modulation of SSVEP amplitude (thought to reflect the magnitude of neural population activity) and phase coherence (thought to reflect neural response synchronization). We presented two stimuli flickering at different frequencies in the left and right visual hemifields and asked observers to shift their attention to either stimulus. Our results demonstrated that attention increased SSVEP phase coherence earlier than it increased SSVEP amplitude, with a positive correlation between the attentional modulations of SSVEP phase coherence and amplitude. Furthermore, the behavioral dynamics of attention shifts were more closely associated with changes in phase coherence than with changes in amplitude. These results are consistent with the possibility that attention increases neural response synchronization, which in turn leads to increased neural population activity.

APA, Harvard, Vancouver, ISO, and other styles

33

HARA, Tomoyoshi, Jun MIURA, Shuji OISHI, Takahiro SHINKAI, Tetsuto MINAMI, and Shigeki NAKAUCHI. "Brain robot interface using SSVEP." Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2016 (2016): 2P1–12b2. http://dx.doi.org/10.1299/jsmermd.2016.2p1-12b2.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Ma, Liang, and Joseph A. Kovacs. "Rapid Detection of Mutations in the Human-DerivedPneumocystis carinii Dihydropteroate Synthase Gene Associated with Sulfa Resistance." Antimicrobial Agents and Chemotherapy 45, no. 3 (March 1, 2001): 776–80. http://dx.doi.org/10.1128/aac.45.3.776-780.2001.

Full text

Abstract:

ABSTRACT Recent studies have shown that point mutations in the dihydropteroate synthase (DHPS) gene of human-derivedPneumocystis carinii are related to exposure to sulfa drugs and possibly represent the emergence of sulfa resistance. We developed a simple single-strand conformation polymorphism (SSCP) method to permit rapid detection of these mutations. With plasmid constructs, SSCP was able to detect as little as 10% of a minority population. The SSCP assay was compared to direct sequencing for typing the DHPS gene by examining 37 clinical isolates with known DHPS sequences and 41 clinical isolates with unknown DHPS sequences. The typing results were consistent between these two methods for all isolates except 11 in which mutations were detected by SSCP but not by direct sequencing. Sequencing of individual clones after subcloning confirmed the presence of mutations in a minority population as determined by SSCP. SSCP is a very simple and sensitive method for rapid identification of P. camii DHPS mutations.

APA, Harvard, Vancouver, ISO, and other styles

35

Bosworth, Brad T., Evelyn A. Dean-Nystrom, Thomas A. Casey, and Holly L. Neibergs. "Differentiation of F18ab+ from F18ac+Escherichia coli by Single-Strand Conformational Polymorphism Analysis of the Major Fimbrial Subunit Gene (fedA)." Clinical Diagnostic Laboratory Immunology 5, no. 3 (May 1, 1998): 299–302. http://dx.doi.org/10.1128/cdli.5.3.299-302.1998.

Full text

Abstract:

ABSTRACT Toxin-producing Escherichia coli expressing F18 fimbriae colonizes the small intestines of weaned pigs and causes diarrhea, edema disease, or both. The F18 family is composed of two antigenic variants, F18ab and F18ac. Because many strains do not express F18 fimbriae in vitro, identification and differentiation of these two variants are difficult. Single-strand conformational polymorphism (SSCP) analysis is a rapid method for identifying genetic mutations and polymorphisms. The F18 major fimbrial subunit genes (fedA) of 138 strains were amplified by PCR, and genetic differences were detected by SSCP analysis. The SSCP analysis of thefedA gene differentiated F18ab+ strains from F18ac+ strains. Most strains classified as F18ab+ by SSCP analysis contained Shiga toxin 2e and enterotoxin genes. Most strains classified as F18ac+ by SSCP analysis contained only enterotoxin genes. The SSCP analysis was a useful method for predicting the antigenicity of F18+ E. coli and could also be used for analysis of other virulence genes in E. coli and other pathogenic bacteria.

APA, Harvard, Vancouver, ISO, and other styles

36

Bahrami, A., S. R. Miraei-Ashtiani, H. Mehrabani-Yeganeh, H. Banani-Rad, and Sh Behzadi. "The association between polymorphism of the GH1 gene and changes in protein structure and carcass traits in Mehraban sheep (Ovis aries)." Animal Production Science 55, no. 5 (2015): 661. http://dx.doi.org/10.1071/an13446.

Full text

Abstract:

The present study indicates an association between carcass traits and genetic polymorphism and changes in the protein structure of the growth hormone 1 (GH1) gene in Mehraban sheep. Polymorphism of the GH1 gene was detected by polymerase chain reaction–single strand conformation polymorphism (PCR–SSCP) and DNA sequencing methods in 463 individuals. Two different structures in the GH1 protein and six single nucleotide polymorphisms were identified. The association of these SSCP patterns and protein structures with carcass traits was analysed. The SSCP patterns were shown to be associated with carcass traits. Individuals with AB SSCP pattern and Type B protein structure had significantly higher fat-tail weight and volume (P < 0.05) than did those individuals with CC SSCP pattern and Type A protein structure. Moreover, CC SSCP pattern and Type A protein structure contributed to low concentration of blood triglycerides (P = 0.004). The results confirmed the importance of GH1 as a candidate gene for marker-assisted selection for carcass-trait variations in sheep.

APA, Harvard, Vancouver, ISO, and other styles

37

Walter, Sabrina, Cliodhna Quigley, and Matthias M. Mueller. "Competitive Interactions of Attentional Resources in Early Visual Cortex during Sustained Visuospatial Attention within or between Visual Hemifields: Evidence for the Different-hemifield Advantage." Journal of Cognitive Neuroscience 26, no. 5 (May 2014): 938–54. http://dx.doi.org/10.1162/jocn_a_00547.

Full text

Abstract:

Performing a task across the left and right visual hemifields results in better performance than in a within-hemifield version of the task, termed the different-hemifield advantage. Although recent studies used transient stimuli that were presented with long ISIs, here we used a continuous objective electrophysiological (EEG) measure of competitive interactions for attentional processing resources in early visual cortex, the steady-state visual evoked potential (SSVEP). We frequency-tagged locations in each visual quadrant and at central fixation by flickering light-emitting diodes (LEDs) at different frequencies to elicit distinguishable SSVEPs. Stimuli were presented for several seconds, and participants were cued to attend to two LEDs either in one (Within) or distributed across left and right visual hemifields (Across). In addition, we introduced two reference measures: one for suppressive interactions between the peripheral LEDs by using a task at fixation where attention was withdrawn from the periphery and another estimating the upper bound of SSVEP amplitude by cueing participants to attend to only one of the peripheral LEDs. We found significantly greater SSVEP amplitude modulations in Across compared with Within hemifield conditions. No differences were found between SSVEP amplitudes elicited by the peripheral LEDs when participants attended to the centrally located LEDs compared with when peripheral LEDs had to be ignored in Across and Within trials. Attending to only one LED elicited the same SSVEP amplitude as Across conditions. Although behavioral data displayed a more complex pattern, SSVEP amplitudes were well in line with the predictions of the different-hemifield advantage account during sustained visuospatial attention.

APA, Harvard, Vancouver, ISO, and other styles

38

Lamti, Hachem A., Mohamed Moncef Ben Khelifa, and Vincent Hugel. "Cerebral and gaze data fusion for wheelchair navigation enhancement: case of distracted users." Robotica 37, no. 2 (September 25, 2018): 246–63. http://dx.doi.org/10.1017/s0263574718000991.

Full text

Abstract:

SUMMARYThe goal of this paper is to present a new hybrid system based on the fusion of gaze data and Steady State Visual Evoked Potentials (SSVEP) not only to command a powered wheelchair, but also to account for users distraction levels (concentrated or distracted). For this purpose, a multi-layer perception neural network was set up in order to combine relevant gazing and blinking features from gaze sequence and brainwave features from occipital and parietal brain regions. The motivation behind this work is the shortages raised from the individual use of gaze-based and SSVEP-based wheelchair command techniques. The proposed framework is based on three main modules: a gaze module to select command and activate the flashing stimuli. An SSVEP module to validate the selected command. In parallel, a distraction level module estimates the intention of the user by mean of behavioral entropy and validates/inhibits the command accordingly. An experimental protocol was set up and the prototype was tested on five paraplegic subjects and compared with standard SSVEP and gaze-based systems. The results showed that the new framework performed better than conventional gaze-based and SSVEP-based systems. Navigation performance was assessed based on navigation time and obstacles collisions.

APA, Harvard, Vancouver, ISO, and other styles

39

Houlden, D. A., Chen Li, M. L. Schwartz, and Marko Katie. "Median Nerve Somatosensory Evoked Potentials and the Glasgow Coma Scale as Predictors of Outcome in Comatose Patients with Head Injuries." Neurosurgery 27, no. 5 (November 1, 1990): 701–8. http://dx.doi.org/10.1227/00006123-199011000-00006.

Full text

Abstract:

Abstract Median nerve somatosensory evoked potential (SSEP) grades and Glasgow Coma Scale (GSC) scores were obtained from 51 patients with head injuries within 1 week after the injury to determine the relationship of these scores, both individually and combined, to outcome scores obtained more than 6 months after the injury. SSEP grading was based on the presence or absence of the cortical evoked potential, the amplitude of the early cortically generated P22 wave form, and the conduction time through the brain (P/N13-N20 interpeak latency). SSEP responses from both sides of the brain were combined and graded from 1 to 6. The GCS was graded without the verbal component (maximum score, 10), because all patients were intubated. All patients were unresponsive to commands. Median SSEP grades correlated better with Glasgow Outcome Scale and Barthel Index scores (R = 0.57 and 0.64, respectively; P < 0.00001) than GCS scores did (R = 0.35 and 0.37, respectively, P < 0.00001), and combining SSEP grades and GCS scores did not improve the predictive power of the model (R = 0.57 and 0.64, respectively; P < 0.00001). All SSEP Grade 1 patients (n = 13) either died or remained in a vegetative state. In contrast, all SSEP Grade 6 patients (n = 7) had a moderate disability or good recovery. This study demonstrates the prognostic value of early quantitative median nerve SSEP grading for patients with head injuries who are unresponsive to commands within 1 week after the injury.

APA, Harvard, Vancouver, ISO, and other styles

40

Jahangiri, Faisal R., Nida Qadir, James Blaylock, Leah Cronce-Solano, and Jason Ramsey. "Waveform Window #46: Radial Nerve SSEP (Rn-SSEP): Is It Reliable?" Neurodiagnostic Journal 59, no. 4 (October 2, 2019): 232–35. http://dx.doi.org/10.1080/21646821.2019.1680085.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Zhang, Yangsong, Li Dong, Rui Zhang, Dezhong Yao, Yu Zhang, and Peng Xu. "An Efficient Frequency Recognition Method Based on Likelihood Ratio Test for SSVEP-Based BCI." Computational and Mathematical Methods in Medicine 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/908719.

Full text

Abstract:

An efficient frequency recognition method is very important for SSVEP-based BCI systems to improve the information transfer rate (ITR). To address this aspect, for the first time, likelihood ratio test (LRT) was utilized to propose a novel multichannel frequency recognition method for SSVEP data. The essence of this new method is to calculate the association between multichannel EEG signals and the reference signals which were constructed according to the stimulus frequency with LRT. For the simulation and real SSVEP data, the proposed method yielded higher recognition accuracy with shorter time window length and was more robust against noise in comparison with the popular canonical correlation analysis- (CCA-) based method and the least absolute shrinkage and selection operator- (LASSO-) based method. The recognition accuracy and information transfer rate (ITR) obtained by the proposed method was higher than those of the CCA-based method and LASSO-based method. The superior results indicate that the LRT method is a promising candidate for reliable frequency recognition in future SSVEP-BCI.

APA, Harvard, Vancouver, ISO, and other styles

42

Ko, Li-Wei, Rupesh Kumar Chikara, Yi-Chieh Lee, and Wen-Chieh Lin. "Exploration of User’s Mental State Changes during Performing Brain–Computer Interface." Sensors 20, no. 11 (June 3, 2020): 3169. http://dx.doi.org/10.3390/s20113169.

Full text

Abstract:

Substantial developments have been established in the past few years for enhancing the performance of brain–computer interface (BCI) based on steady-state visual evoked potential (SSVEP). The past SSVEP-BCI studies utilized different target frequencies with flashing stimuli in many different applications. However, it is not easy to recognize user’s mental state changes when performing the SSVEP-BCI task. What we could observe was the increasing EEG power of the target frequency from the user’s visual area. BCI user’s cognitive state changes, especially in mental focus state or lost-in-thought state, will affect the BCI performance in sustained usage of SSVEP. Therefore, how to differentiate BCI users’ physiological state through exploring their neural activities changes while performing SSVEP is a key technology for enhancing the BCI performance. In this study, we designed a new BCI experiment which combined working memory task into the flashing targets of SSVEP task using 12 Hz or 30 Hz frequencies. Through exploring the EEG activity changes corresponding to the working memory and SSVEP task performance, we can recognize if the user’s cognitive state is in mental focus or lost-in-thought. Experiment results show that the delta (1–4 Hz), theta (4–7 Hz), and beta (13–30 Hz) EEG activities increased more in mental focus than in lost-in-thought state at the frontal lobe. In addition, the powers of the delta (1–4 Hz), alpha (8–12 Hz), and beta (13–30 Hz) bands increased more in mental focus in comparison with the lost-in-thought state at the occipital lobe. In addition, the average classification performance across subjects for the KNN and the Bayesian network classifiers were observed as 77% to 80%. These results show how mental state changes affect the performance of BCI users. In this work, we developed a new scenario to recognize the user’s cognitive state during performing BCI tasks. These findings can be used as the novel neural markers in future BCI developments.

APA, Harvard, Vancouver, ISO, and other styles

43

Houlden, David A., Mark I. Boulos, Brian J. Murray, Loretta Norton, and G. Bryan Young. "Giant Somatosensory Evoked Potentials Coincident With Epileptiform Discharges in Acutely Comatose Patients." Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques 42, no. 5 (July 20, 2015): 317–23. http://dx.doi.org/10.1017/cjn.2015.237.

Full text

Abstract:

AbstractBackgroundThe amplitude of the cortically generated somatosensory evoked potential (SSEP) is used to predict outcome in comatose patients. The relationship between epileptiform discharges and SSEP amplitude has not been elucidated in those patients.MethodsBilateral median nerve SSEP and electroencephalograph (EEG) studies were performed in a comatose patient (patient 1) 1 day after cardiac surgery and repeated 4 days later. He had tranexamic acid administered before and during surgery. Another comatose patient (patient 2) had the same studies performed 1 day after sustaining 10 minutes of pulseless electrical cardiac activity.ResultsBoth comatose patients had epileptiform discharges (on EEG) that were coincident with giant cortically generated SSEPs. In patient 1, the EEG and SSEP studies repeated 5 days postoperatively showed no epileptiform discharges, and the cortically generated SSEP amplitude was decreased (normalized) compared with that obtained one day postoperatively. He emerged from coma and had a good recovery. Patient 2 died shortly after EEG and SSEP testing.ConclusionsEpileptiform discharges were associated with giant cortically generated median nerve SSEP amplitude (tranexamic acid was implicated in patient 1 and anoxic brain injury in patient 2). Accordingly, those who use the amplitude of cortically generated SSEPs for predicting outcome in comatose patients should consider the presence of epileptiform discharges (detected by EEG) as a potential confounding factor.

APA, Harvard, Vancouver, ISO, and other styles

44

Vergeer, Mark, Juraj Mesik, Yihwa Baek, Kelton Wilmerding, and Stephen Engel. "Contrast adaptation reduces SSVEP amplitude." Journal of Vision 17, no. 10 (August 31, 2017): 485. http://dx.doi.org/10.1167/17.10.485.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Crawford, Sally. "SSCIP: The First 10 Years." Childhood in the Past 10, no. 1 (January 2, 2017): 10–15. http://dx.doi.org/10.1080/17585716.2017.1305078.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Wang, Xin, Ye Han, Enlai Xiao, Kai Zhang, and Yongqiang Ma. "Sulfated Modification of Polysaccharides from Sweet Corncob and Its Antiglycation Activity in Streptozotocin Induced Diabetic Rats." Journal of Biobased Materials and Bioenergy 15, no. 3 (June 1, 2021): 353–59. http://dx.doi.org/10.1166/jbmb.2021.2068.

Full text

Abstract:

Polysaccharides extracted from sweet corncob (SCP) were modified by sulfuric acid to sulfated sweet corncob (SSCP) with a molecular weight of 13.412 kDa, and their antiglycation activity was studied. SSCP had high inhibitory effects on glycation and showed antiglycation activity stronger than that of SCP in vitro. The maximum inhibition rates of the Amadori products, dicarbonyl compounds, caboxymethyl-lysine (CML), and advanced glycation end products (AGEs) were 76.35, 73.78, 52.79, and 76.36%, respectively. SSCP effectively increased body weight, reduced blood glucose, and increased oral glucose tolerance in streptozotocin (STZ)-induced diabetic rats in vivo. Furthermore, SSCP inhibited AGE formation in liver tissue and repaired pancreatic injury. The results in vivo and in vitro reflect that SSCP has antiglycation effects, which may be closely related to its antidiabetic effects.

APA, Harvard, Vancouver, ISO, and other styles

47

Choi, Kang-min, Seonghun Park, and Chang-Hwan Im. "Comparison of Visual Stimuli for Steady-State Visual Evoked Potential-Based Brain-Computer Interfaces in Virtual Reality Environment in terms of Classification Accuracy and Visual Comfort." Computational Intelligence and Neuroscience 2019 (July 1, 2019): 1–7. http://dx.doi.org/10.1155/2019/9680697.

Full text

Abstract:

Recent studies on brain-computer interfaces (BCIs) based on the steady-state visual evoked potential (SSVEP) have demonstrated their use to control objects or generate commands in virtual reality (VR) environments. However, most SSVEP-based BCI studies performed in VR environments have adopted visual stimuli that are typically used in conventional LCD environments without considering the differences in the rendering devices (head-mounted displays (HMDs) used in the VR environments). The proximity between the visual stimuli and the eyes in HMDs can readily cause eyestrain, degrading the overall performance of SSVEP-based BCIs. Therefore, in the present study, we have tested two different types of visual stimuli—pattern-reversal checkerboard stimulus (PRCS) and grow/shrink stimulus (GSS)—on young healthy participants wearing HMDs. Preliminary experiments were conducted to investigate the visual comfort of each participant during the presentation of the visual stimuli. In subsequent online avatar control experiments, we observed considerable differences in the classification accuracy of individual participants based on the type of visual stimuli used to elicit SSVEP. Interestingly, there was a close relationship between the subjective visual comfort score and the online performance of the SSVEP-based BCI: most participants showed better classification accuracy under visual stimulus they were more comfortable with. Our experimental results suggest the importance of an appropriate visual stimulus to enhance the overall performance of the SSVEP-based BCIs in VR environments. In addition, it is expected that the appropriate visual stimulus for a certain user might be readily selected by surveying the user’s visual comfort for different visual stimuli, without the need for the actual BCI experiments.

APA, Harvard, Vancouver, ISO, and other styles

48

Trigui, Omar, Sawsan Daoud, Mohamed Ghorbel, and Chokri Mhiri. "SSVEP Enhancement Using Moving Average Filter Controlled by Phase Features." Computational Intelligence and Neuroscience 2020 (May 8, 2020): 1–11. http://dx.doi.org/10.1155/2020/7459587.

Full text

Abstract:

Brain-computer interface (BCI) systems translate the human neurophysiological activities into commands through EEG analysis. Improving the BCI performances leads to faster and easier use and less fatigue. In this study, we proposed a new prepossessing approach to increase the robustness of a steady-state visual evoked potential (SSVEP) based BCI. Inspiring from the known properties of the SSVEP frequency components, the goal was to enhance the signal quality by making it more convenient to be interpreted by the decision-making step. We first investigated the potential to detect the deteriorating periods based on the physiological properties of the SSVEP. The proposed system localizes the intervals which can obscure the SSVEP frequencies by a new algorithm founded on the processing and the analysis of the instantaneous phase. The piecewise linear regression allows a sampler comprehension of the phase signal. Then, these intervals are filtered by the moving average filter to enhance the SSVEP quality. Finally, the decision making is made by the canonical correlation analysis (CCA) algorithm. The results of experiments, using real EEG signals from five subjects, show that the proposed approach significantly increases the performances in terms of accuracy and information transfer rate by about 7.3% and 3.85 bits/min, respectively, in case of 2 s segment length. On the other hand, the spatial filtering methods of the literature weaken the system performances.

APA, Harvard, Vancouver, ISO, and other styles

49

Owen, Caroline M., John Patterson, and Richard B. Silberstein. "Olfactory Modulation of Steady- State Visual Evoked Potential Topography in Comparison with Differences in Odor Sensitivity." Journal of Psychophysiology 16, no. 2 (January 2002): 71–81. http://dx.doi.org/10.1027//0269-8803.16.2.71.

Full text

Abstract:

Summary Research was undertaken to determine whether olfactory stimulation can alter steady-state visual evoked potential (SSVEP) topography. Odor-air and air-only stimuli were used to determine whether the SSVEP would be altered when odor was present. Comparisons were also made of the topographic activation associated with air and odor stimulation, with the view toward determining whether the revealed topographic activity would differentiate levels of olfactory sensitivity by clearly identifying supra- and subthreshold odor responses. Using a continuous respiration olfactometer (CRO) to precisely deliver an odor or air stimulus synchronously with the natural respiration, air or odor (n-butanol) was randomly delivered into the inspiratory airstream during the simultaneous recording of SSVEPs and subjective behavioral responses. Subjects were placed in groups based on subjective odor detection response: “yes” and “no” detection groups. In comparison to air, SSVEP topography revealed cortical changes in response to odor stimulation for both response groups, with topographic changes evident for those unable to perceive the odor, showing the presence of a subconscious physiological odor detection response. Differences in regional SSVEP topography were shown for those who reported smelling the odor compared with those who remained unaware of the odor. These changes revealed olfactory modulation of SSVEP topography related to odor awareness and sensitivity and therefore odor concentration relative to thresholds.

APA, Harvard, Vancouver, ISO, and other styles

50

Deutsch, Harel, Marc Arginteanu, Karen Manhart, Noel Perin, Martin Camins, Frank Moore, A. Abe Steinberger, and Donald J. Weisz. "Somatosensory evoked potential monitoring in anterior thoracic vertebrectomy." Journal of Neurosurgery: Spine 92, no. 2 (April 2000): 155–61. http://dx.doi.org/10.3171/spi.2000.92.2.0155.

Full text

Abstract:

Object. Spine surgeons have used intraoperative cortical and subcortical somatosensory evoked potential (SSEP) monitoring to detect changes in spinal cord function when intraoperative procedures can be performed to prevent neurological deterioration. However, the reliability of SSEP monitoring as applied to anterior thoracic vertebral body resections has not been rigorously assessed. Methods. The authors retrospectively reviewed hospital charts and operating room records obtained between August 1993 and December 1998 and found that SSEP monitoring was used in 44 surgical procedures involving an anterior approach for thoracic vertebral body resections. There were no patients in whom SSEP changes did not return to baseline during the surgical procedure. Patients in four cases, despite their stable SSEP recordings throughout the procedure, were noted immediately postoperatively to have experienced significant neurological deterioration. The false-negative rate in SSEP monitoring was 9%. Sensitivity was determined to be 0%. Conclusions. It is important to recognize high false-negative rates and low sensitivity of SSEP monitoring when it is used to record spinal cord function during anterior approaches for thoracic vertebrectomies. The insensitivity of SSEPs for motor deterioration during anterior thoracic vertebrectomies is likely due to the limitation of SSEPs, which monitor only posterior column function whereas motor paths are conveyed in the anterior and anterolateral spinal cord. The authors believe that SSEPs can not be relied on to detect reversible spinal damage during anterior thoracic vertebrectomies.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'SSCEP'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles