Measuring the face-sensitive N170 with a gaming EEG system: A validation study

BACKGROUND

The N170 is a "face-sensitive" event-related potential (ERP) that occurs at around 170ms over occipito-temporal brain regions. The N170's potential to provide insight into the neural processing of faces in certain populations (e.g., children and adults with cognitive impairments) is limited by its measurement in scientific laboratories that can appear threatening to some people.

NEW METHOD

The advent of cheap, easy-to-use portable gaming EEG systems provides an opportunity to record EEG in new contexts and populations. This study tested the validity of the face-sensitive N170 ERP measured with an adapted commercial EEG system (the Emotiv EPOC) that is used at home by gamers.

RESULTS

The N170 recorded through both the gaming EEG system and the research EEG system exhibited face-sensitivity, with larger mean amplitudes in response to the face stimuli than the non-face stimuli, and a delayed N170 peak in response to face inversion.

COMPARISON WITH EXISTING METHOD

The EPOC system produced very similar N170 ERPs to a research-grade Neuroscan system, and was capable of recording face-sensitivity in the N170, validating its use as research tool in this arena.

CONCLUSIONS

This opens new possibilities for measuring the face-sensitive N170 ERP in people who cannot travel to a traditional ERP laboratory (e.g., elderly people in care), who cannot tolerate laboratory conditions (e.g., people with autism), or who need to be tested in situ for practical or experimental reasons (e.g., children in schools).

Validation of the Emotiv EPOC EEG system for research quality auditory event-related potentials in children

Background. Previous work has demonstrated that a commercial gaming electroencephalography (EEG) system, Emotiv EPOC, can be adjusted to provide valid auditory event-related potentials (ERPs) in adults that are comparable to ERPs recorded by a research-grade EEG system, Neuroscan. The aim of the current study was to determine if the same was true for children.

Method. An adapted Emotiv EPOC system and Neuroscan system were used to make simultaneous EEG recordings in nineteen 6- to 12-year-old children under “passive” and “active” listening conditions. In the passive condition, children were instructed to watch a silent DVD and ignore 566 standard (1,000 Hz) and 100 deviant (1,200 Hz) tones. In the active condition, they listened to the same stimuli, and were asked to count the number of ‘high’ (i.e., deviant) tones.

Results. Intraclass correlations (ICCs) indicated that the ERP morphology recorded with the two systems was very similar for the P1, N1, P2, N2, and P3 ERP peaks (r = .82 to .95) in both passive and active conditions, and less so, though still strong, for mismatch negativity ERP component (MMN; r = .67 to .74). There were few differences between peak amplitude and latency estimates for the two systems.

Conclusions. An adapted EPOC EEG system can be used to index children’s late auditory ERP peaks (i.e., P1, N1, P2, N2, P3) and their MMN ERP component.

Validation of the Emotiv EPOC(®) EEG gaming system for measuring research quality auditory ERPs

Background. Auditory event-related potentials (ERPs) have proved useful in investigating the role of auditory processing in cognitive disorders such as developmental dyslexia, specific language impairment (SLI), attention deficit hyperactivity disorder (ADHD), schizophrenia, and autism. However, laboratory recordings of auditory ERPs can be lengthy, uncomfortable, or threatening for some participants - particularly children. Recently, a commercial gaming electroencephalography (EEG) system has been developed that is portable, inexpensive, and easy to set up. In this study we tested if auditory ERPs measured using a gaming EEG system (Emotiv EPOC(®), www.emotiv.com) were equivalent to those measured by a widely-used, laboratory-based, research EEG system (Neuroscan). Methods. We simultaneously recorded EEGs with the research and gaming EEG systems, whilst presenting 21 adults with 566 standard (1000 Hz) and 100 deviant (1200 Hz) tones under passive (non-attended) and active (attended) conditions. The onset of each tone was marked in the EEGs using a parallel port pulse (Neuroscan) or a stimulus-generated electrical pulse injected into the O1 and O2 channels (Emotiv EPOC(®)). These markers were used to calculate research and gaming EEG system late auditory ERPs (P1, N1, P2, N2, and P3 peaks) and the mismatch negativity (MMN) in active and passive listening conditions for each participant. Results. Analyses were restricted to frontal sites as these are most commonly reported in auditory ERP research. Intra-class correlations (ICCs) indicated that the morphology of the research and gaming EEG system late auditory ERP waveforms were similar across all participants, but that the research and gaming EEG system MMN waveforms were only similar for participants with non-noisy MMN waveforms (N = 11 out of 21). Peak amplitude and latency measures revealed no significant differences between the size or the timing of the auditory P1, N1, P2, N2, P3, and MMN peaks. Conclusions. Our findings suggest that the gaming EEG system may prove a valid alternative to laboratory ERP systems for recording reliable late auditory ERPs (P1, N1, P2, N2, and the P3) over the frontal cortices. In the future, the gaming EEG system may also prove useful for measuring less reliable ERPs, such as the MMN, if the reliability of such ERPs can be boosted to the same level as late auditory ERPs.

Biomedical signal acquisition with streaming wireless communication for recording evoked potentials

BACKGROUND

Commercial electrophysiology systems for recording evoked potentials always connect patients to the acquisition unit via long wires. Wires guarantee timely transfer of signals for synchronization with the stimuli, but they are susceptible to electromagnetic and electrostatic interferences. Though wireless solutions are readily available (e.g. Bluetooth), they introduce high delay variability that will distort the evoked potential traces. We developed a complete wireless acquisition system with a fixed delay.

METHODS

The system supports up to 4 bipolar channels; each is amplified by 20,000× and digitized to 24 bits. The system incorporates the "driven-right-leg" circuit to lower the common noise. Data are continuously streamed using radio-frequency transmission operating at 915 MHz and then tagged with the stimulus SYNC signal at the receiver. The delay, noise level and transmission error rate were measured. Flash visual evoked potentials were recorded monocularly from both eyes of six adults with normal vision. The signals were acquired via wireless and wired transmissions simultaneously. The recording was repeated on some participants within 2 weeks.

RESULTS

The delay was constant at 20 ms. The system noise was white and Gaussian (2 microvolts RMS). The transmission error rate was about one per million packets. The VEPs recorded with wireless transmission were consistent with those with wired transmission. The VEP amplitudes and shapes showed good intra-session and inter-session reproducibility and were consistent across eyes.

CONCLUSIONS

The wireless acquisition system can reliably record visual evoked potentials. It has a constant delay of 20 ms and very low error rate.

Optimal erasure protection strategy for scalably compressed data with tree-structured dependencies

This paper is concerned with the transmission of scalably compressed data sources over lossy channels. Specifically, this paper is concerned with packet networks or, more generally, erasure channels. Previous work has generally assumed that the source elements form linear dependencies. The contribution of this paper is an unequal erasure protection algorithm which is able to take advantage of scalable data with more general dependency structures. In particular, the proposed scheme is adapted to data with tree-structured dependencies. The source elements are allocated to clusters of packets according to their dependency structure, subject to constraints on packet size and channel code-word length. Given a packet cluster arrangement, source elements are assigned optimal channel codes subject to a constraint on the total transmission length. Experimental results confirm the benefit associated with exploiting the actual dependency structure of the data.

Optimal erasure protection for scalably compressed video streams with limited retransmission

This paper shows how the priority encoding transmission (PET) framework may be leveraged to exploit both unequal error protection and limited retransmission for RD-optimized delivery of streaming media. Previous work on scalable media protection with PET has largely ignored the possibility of retransmission. Conversely, the PET framework has not been harnessed by the substantial body of previous work on RD optimized hybrid forward error correction/automatic repeat request schemes. We limit our attention to sources which can be modeled as independently compressed frames (e.g., video frames), where each element in the scalable representation of each frame can be transmitted in one or both of two transmission slots. An optimization algorithm determines the level of protection which should be assigned to each element in each slot, subject to transmission bandwidth constraints. To balance the protection assigned to elements which are being transmitted for the first time with those which are being retransmitted, the proposed algorithm formulates a collection of hypotheses concerning its own behavior in future transmission slots. We show how the PET framework allows for a decoupled optimization algorithm with only modest complexity. Experimental results obtained with Motion JPEG2000 compressed video demonstrate that substantial performance benefits can be obtained using the proposed framework.

The development of a new model for community telemedicine services

Two trials of a telemedicine monitoring system were conducted in the UK. The SAFE21 system records the patient's physiological data, which are transmitted via a modem to the health service provider. The first trial was conducted on nine muscular dystrophy patients under 18 years of age. Eight of the patients felt that the monitoring system was reliable and were happy with it, as it avoided the need to go to hospital for monitoring. The second trial was carried out on 14 patients suffering from respiratory illness. Thirteen of these patients felt that the service was useful and 12 reported satisfaction with the system. The SAFE21 telemedicine monitoring system appears to be an acceptable means of delivering care.

Recurrent pregnancy loss and diminished ovarian reserve

OBJECTIVE

To determine the incidence of diminished ovarian reserve (OR) in patients with recurrent pregnancy loss (RPL).

DESIGN

Retrospective chart review.

SETTING

Tertiary fertility center.

PATIENT(S)

Six hundred ninety-two women undergoing a fertility evaluation.

INTERVENTION(S)

Clomiphene citrate challenge test (CCCT).

MAIN OUTCOME MEASURE(S)

FSH concentrations measured on menstrual days 3 and 10.

RESULT(S)

Forty-four women were diagnosed with RPL (+RPL), and 648 women had non-RPL diagnoses (-RPL). Compared with -RPL women, women with +RPL were younger (following statistics are listed as +RPL vs. -RPL, respectively; 34 +/- 5 vs. 35 +/- 4 y) but had similar menstrual cycle length (29 +/- 4 vs. 28 +/- 4 d), and lower day 3 FSH levels (8.9 + 7 vs. 11 +/- 9 mIU/mL) and similar day 10 FSH levels (11 +/- 8 vs. 12 +/- 11 mIU/mL). Eight of 44 women with +RPL (18%) had an abnormal CCCT, compared with 117/648 (18%) of women in the -RPL group. For women with normal OR, delivery rates were similar for -RPL and +RPL patients. For women with an abnormal CCCT, delivery rates were < 5%.

CONCLUSION(S)

Women with RPL have a similar incidence of diminished OR as the general infertile population. Reproductive outcome for patients with an abnormal CCCT is equally poor for both groups. Ovarian reserve screening should be considered in the work-up of RPL before initiation of anticoagulant or immunotherapy.

A pan-European social alarm system

SAFE 21 is a pan-European research and development project which will take social alarms into the twenty-first century. It is run by a consortium of eight organizations, with financial support from the European Commission. SAFE 21 will use existing infrastructure to deliver a much broader range of services and extend availability to users who are currently excluded. The project aims: to develop a social alarm that will work from anywhere inside the home, using a neck-worn speech-pendant and outside the home making use of radio cellphone and global positioning technology; to demonstrate how telemedicine can be incorporated at marginal costs, by exploiting the existing social alarm infrastructure; to demonstrate a shared control centre that facilitates emergency services, medical, welfare and social professionals working together to support a broad-based social alarm system; to provide access to social alarms for deaf users, who are currently excluded.

The effect of intrauterine diethylstilbestrol exposure on ovarian reserve screening

OBJECTIVE

Our goal was to evaluate the effect of intrauterine diethylstilbestrol exposure on ovarian reserve.

STUDY DESIGN

Four hundred two women underwent ovarian reserve screening. Twenty had intrauterine diethylstilbestrol exposure, and 382 women did not have exposure. The groups were compared regarding age, the incidence of diminished ovarian reserve, and cycle length. Nine women with and 204 women without diethylstilbestrol exposure underwent comparison of the total human menopausal gonadotropin dose, the day of human chorionic gonadotropin administration, the peak estradiol level, and the number of mature follicles.

RESULTS

The diethylstilbestrol-exposed women were similar in age (37 +/- 3.4 years) to the non-diethylstilbestrol-exposed women (35 +/- 4.4 years, p > 0.05). Three of 20 exposed women (15.8%) and 57 of 382 nonexposed women (15.3%) had diminished ovarian reserve (p = 0.41). When the exposed women were compared with the nonexposed subjects, the amounts of human menopausal gonadotropin (30 +/- 10 vs 33.7 +/- 10.6 ampules) required to achieve peak estradiol levels (633 +/- 323 vs 817 +/- 518 pg/ ml) with comparable numbers of follicles (5.7 +/- 2.7 vs 5.4 +/- 2.8) on the day of human chorionic gonadotropin administration were similar (p > 0.05).

CONCLUSIONS

The diethylstilbestrol-exposed and nonexposed women had a similar incidence of diminished ovarian reserve and a similar follicular response to gonadotropins.

Premature luteinization during controlled ovarian hyperstimulation for in vitro fertilization-embryo transfer has no impact on pregnancy outcome

OBJECTIVE

To determine if elevated serum P concentration on the day of hCG administration or P area under the curve (AUC) impacts on pregnancy rates (PRs) in IVF-ET cycles.

DESIGN

Retrospective study.

PATIENT(S)

One hundred thirty-three couples underwent IVF-ET using luteal GnRH-agonist suppression followed by hyperstimulation with gonadotropins. Patient cycles were controlled for female age, ovarian reserve, male factor with intracytoplasmic sperm injection (ICSI), endometrial thickness and pattern, number of embryos, and number of high-quality embryos transferred, and cell stage at transfer. Pregnancy was defined as an ongoing pregnancy > 20 weeks.

RESULT(S)

Patients and cycle parameters did not differ significantly based on the control parameters. Similar numbers of severe male factors treated by ICSI were in each group with similar PRs. Pregnancy rates and implantation rates did not differ based on P levels < or = 0.9, < or = 1.1, and < or = 1.4 ng/mL (conversion factor to SI unit, 3.18). Serum P concentrations per total eggs retrieved or per mature egg retrieved did not influence pregnancy outcome. Efficiency curves for serum P levels and P AUC did not demonstrate any differences in PR. At very high serum P (P > 2.0 ng/mL) samples size limits the ability of these data to rule out a negative effect.

CONCLUSION(S)

Serum P levels (and P AUC) commonly encountered during cycles of IVF-ET have no impact on pregnancy outcome.

Differentiating benign from malignant lung lesions using "quantitative" parameters of FDG PET images

Fluorine-18 labeled deoxyglucose positron-emission tomography (FDG-PET) applications in oncology include the differential diagnosis of chest masses and single pulmonary nodules. However, FDG is not tumor-specific; rather, it also accumulates in inflammatory processes. This study was performed to identify image parameters that would improve the specificity of PET.

METHODS

Twenty-six patients who had benign and malignant lung lesions were examined retrospectively. Positron-emission tomography data were acquired in dynamic scanning mode after intravenous bolus of 250-402 MBq of FDG. Standardized uptake values (SUVs) were calculated and Patlak analyses were performed in selected regions of interest in the PET images. Positron-emission tomography results were related to histological diagnosis (N = 49) or clinical follow-up (N = 3).

RESULTS

The specificity and sensitivity of the original PET scan reports, which was based on visual image interpretation and loosely applied SUVs, was 100% and 73%, respectively. Using the SUVs with a cut-off value of 3.8 and Kpat value with a cut-off at 0.025 min-1 improved the specificity to 81% and 85%.

CONCLUSION

FDG-PET image interpretation can be facilitated by using SUV information or the accumulation rate of the radiotracer (Patlak). With additional validation, this method could have a significant cost-effective impact on the medical/surgical management of chest masses.

Endometrial thickness is predictive of histologic endometrial maturation in women undergoing hormone replacement for ovum donation

OBJECTIVE

To determine if ultrasonographic endometrial pattern or thickness is predictive of histologic endometrial maturation in women undergoing hormone replacement for ovum donation.

DESIGN

Ultrasonographic endometrial thickness and pattern were determined and compared with histologic assessment of endometrial maturation.

PATIENTS

Forty-six women underwent 52 preparatory cycles for ovum donation. Transvaginal ultrasound (US) was performed after 14 days of E2 replacement and, after 12 days of P, an endometrial biopsy was performed. In 12 cycles, a continuous dose of 2 mg/d E2 was administered. In cycles with out-of-phase biopsies (dated earlier than day 24) and in the last 34 cycles, all women received an escalating dose of E2 before initiation of P. Additionally, the 46 women underwent 55 ETs with USs performed on cycle day 15.

RESULTS

Six women had abnormal biopsies in their first preparatory cycle on the continuous E2 protocol, which normalized with the escalating protocol. All other women had normal biopsies. Women with abnormal biopsies had significantly thinner endometrium (< or = 6 mm) but similar endometrial patterns compared with women with normal biopsies. In women having US in preparatory and transfer cycles, there were no differences in endometrial thickness or pattern between examinations.

CONCLUSIONS

Endometrial thickness > or = 7 mm in hormone replacement cycles predicts in phase endometrial histology and can replace the endometrial biopsy.

Efficacy of selection criteria for ovarian reserve screening using the clomiphene citrate challenge test in a tertiary fertility center population

OBJECTIVE

To examine selection criteria for ovarian reserve screening.

DESIGN

Retrospective study.

PATIENTS

Two hundred nineteen women underwent testing for ovarian reserve for woman's age > 35 years, any age with unexplained infertility, one ovary, or a poor response to hMG.

INTERVENTIONS

Clomiphene citrate challenge test.

MAIN OUTCOME MEASURES

Frequency of abnormal ovarian reserve screening, menstrual cycle parameters, response to hMG, and pregnancy outcome by screening criteria.

RESULTS

One hundred eighty-four (84.0%) women had a normal ovarian reserve screening test; 35 (16.0%) had an abnormal ovarian reserve screening test. Twenty-six had abnormal ovarian reserve screening when screened by age, 14 for unexplained infertility, 5 for poor response to hMG, and 6 for one ovary. Fifteen women with abnormal ovarian reserve screening had more than one indication for screening. For women attempting pregnancy (n = 182), 49 of 148 (33.1%) with normal ovarian reserve screening became pregnant compared with 2 of 34 (5.9%) with abnormal ovarian reserve screening. Within each screening category, women with abnormal ovarian reserve had menstrual cycle parameters associated with a short follicular phase, required more hMG, and responded poorly to hMG.

CONCLUSIONS

One of six women undergoing ovarian reserve screening had an abnormal test, which was associated a poor reproductive outcome. Age was the most important single criteria. Selected ovarian reserve screening is simple and inexpensive and should be offered to all fertility patients meeting the specific screening criteria listed above.

Evaluation of the reproductive performance of women with elevated day 10 progesterone levels during ovarian reserve screening

OBJECTIVES

To evaluate the relationship of elevated day 10 P levels (> or = 1.1 ng/mL, conversion factor to SI unit, 3.18) during ovarian reserve screening and reproductive performance.

DESIGN

Prospective screening with longitudinal follow-up.

INTERVENTIONS

One hundred seven women underwent ovarian reserve screening with a clomiphene citrate challenge test.

MAIN OUTCOME MEASURES

Serum FSH, LH, and E2 levels were determined on cycle day 3 and FSH, LH, and P levels were determined on day 10. A fertility evaluation was completed and a treatment plan was instituted.

RESULTS

Twenty-two of 107 (20.6%) women had day 10 P levels > or = 1.1 ng/mL. Women with elevated day 10 P levels were similar in age to women with normal day 10 P levels (< or = 0.9 ng/mL) but had significantly shorter menstrual cycles, higher day 3 and day 10 FSH levels, higher day 3 E2 levels, and higher day 10 LH levels than women with normal day 10 P levels. During ovarian hyperstimulation, women with elevated day 10 P levels required more ampules of hMG, had lower peak E2 levels, and had fewer mature follicles than women with a normal day 10 P level. Sixteen of 85 (18.8%) women with normal day 10 P levels became pregnant, but none of the 22 women with elevated day 10 P levels became pregnant. The incidence of diminished ovarian reserve was higher in women with elevated day 10 P levels (13/22; 59%) when compared with women with a normal day 10 P levels (9/85; 10.6%).

CONCLUSIONS

Elevated day 10 P levels (> or = 1.1 ng/mL) during ovarian reserve screening is associated with diminished ovarian reserve and correlates with menstrual cycle parameters associated with a short follicular phase and poor reproductive performance.

Primary microsurgery for postinflammatory tubal infertility

Pelvic inflammatory disease is a common cause of tubal infertility. The pregnancy outcomes in 161 patients who underwent primary microsurgical tuboplasty for postinflammatory tubal disease at the Mayo Clinic from 1977 through 1981 were evaluated. The outcome (3-year rate) was evaluated for each category of microsurgical procedures. The proximal anastomosis group had a conception rate of 71% (50% live births, 30% spontaneous abortions, 6% ectopic pregnancies). The terminal salpingoneostomy group, which accounted for the largest number of procedures, had a conception rate of 47% (32% live births, 12% spontaneous abortions, 11% ectopic pregnancies). Even after microsurgical tubal reconstruction, most women do not achieve a live birth. Pregnancy outcome is probably related to several factors reflecting the severity of pre-existing intrinsic damage. Prognostic factors that may better predict pregnancy outcome are discussed.