Stability, change, and reliable individual differences in electroencephalography measures: a lifespan perspective on progress and opportunities

Electroencephalographic (EEG) methods have great potential to serve both basic and clinical science approaches to understand individual differences in human neural function. Importantly, the psychometric properties of EEG data, such as internal consistency and test-retest reliability, constrain their ability to differentiate individuals successfully. Rapid and recent technological and computational advancements in EEG research make it timely to revisit the topic of psychometric reliability in the context of individual difference analyses. Moreover, pediatric and clinical samples provide some of the most salient and urgent opportunities to apply individual difference approaches, but the changes these populations experience over time also provide unique challenges from a psychometric perspective. Here we take a developmental neuroscience perspective to consider progress and new opportunities for parsing the reliability and stability of individual differences in EEG measurements across the lifespan. We first conceptually map the different profiles of measurement reliability expected for different types of individual difference analyses over the lifespan. Next, we summarize and evaluate the state of the field's empirical knowledge and need for testing measurement reliability, both internal consistency and test-retest reliability, across EEG measures of power, event-related potentials, nonlinearity, and functional connectivity across ages. Finally, we highlight how standardized pre-processing software for EEG denoising and empirical metrics of individual data quality may be used to further improve EEG-based individual differences research moving forward. We also include recommendations and resources throughout that individual researchers can implement to improve the utility and reproducibility of individual differences analyses with EEG across the lifespan.

The HAPPE plus Event-Related (HAPPE+ER) software: A standardized preprocessing pipeline for event-related potential analyses

Event-Related Potential (ERP) designs are a common method for interrogating neurocognitive function with electroencephalography (EEG). However, the traditional method of preprocessing ERP data is manual-editing - a subjective, time-consuming processes. A number of automated pipelines have recently been created to address the need for standardization, automation, and quantification of EEG data pre-processing; however, few are optimized for ERP analyses (especially in developmental or clinical populations). We propose and validate the HAPPE plus Event-Related (HAPPE+ER) software, a standardized and automated pre-processing pipeline optimized for ERP analyses across the lifespan. HAPPE+ER processes event-related potential data from raw files through preprocessing and generation of event-related potentials for statistical analyses. HAPPE+ER also includes post-processing reports of both data quality and pipeline quality metrics to facilitate the evaluation and reporting of data processing in a standardized manner. Finally, HAPPE+ER includes post-processing scripts to facilitate validating HAPPE+ER performance and/or comparing to performance of other preprocessing pipelines in users' own data via simulated ERPs. We describe multiple approaches with simulated and real ERP data to optimize pipeline performance and compare to other methods and pipelines. HAPPE+ER software is freely available under the terms of GNU General Public License at https://www.gnu.org/licenses/#GPL.

HAPPILEE: HAPPE In Low Electrode Electroencephalography, a standardized pre-processing software for lower density recordings

Lower-density Electroencephalography (EEG) recordings (from 1 to approximately 32 electrodes) are widely-used in research and clinical practice and enable scalable brain function measurement across a variety of settings and populations. Though a number of automated pipelines have recently been proposed to standardize and optimize EEG pre-processing for high-density systems with state-of-the-art methods, few solutions have emerged that are compatible with lower-density systems. However, lower-density data often include long recording times and/or large sample sizes that would benefit from similar standardization and automation with contemporary methods. To address this need, we propose the HAPPE In Low Electrode Electroencephalography (HAPPILEE) pipeline as a standardized, automated pipeline optimized for EEG recordings with lower density channel layouts of any size. HAPPILEE processes task-free (e.g., resting-state) and task-related EEG (including event-related potential data by interfacing with the HAPPE+ER pipeline), from raw files through a series of processing steps including filtering, line noise reduction, bad channel detection, artifact correction from continuous data, segmentation, and bad segment rejection that have all been optimized for lower density data. HAPPILEE also includes post-processing reports of data and pipeline quality metrics to facilitate the evaluation and reporting of data quality and processing-related changes to the data in a standardized manner. Here the HAPPILEE steps and their optimization with both recorded and simulated EEG data are described. HAPPILEE's performance is then compared relative to other artifact correction and rejection strategies. The HAPPILEE pipeline is freely available as part of HAPPE 2.0 software under the terms of the GNU General Public License at: https://github.com/PINE-Lab/HAPPE.

Bevacizumab, paclitaxel and carboplatin for advanced ovarian cancer: low risk of gastrointestinal and cardiovascular toxicity

The purpose of this preliminary study was to retrospectively assess the incidence of bowel perforation and hypertension in two separate advanced ovarian cancer patient populations following first-line therapy, comprising paclitaxel, carboplatin and bevacizumab. The first 20 patients were treated with six cycles of paclitaxel (175 mg/m2), carboplatin (AUC of 5 i.v.), and bevacizumab (15 mg/kg of body weight); q21 days per an independent protocol. The subsequent patients (n = 12) were administered weekly paclitaxel (80 mg/m2), carboplatin (AUC of 5 i.v.) every four weeks, and bevacizumab (10 mg/kg of body weight) every two weeks for six cycles according to a separate, independent protocol. Bevacizumab was not added to either chemotherapy regimen until cycle 2. In both groups patients who achieved a complete response, partial response or stable disease at the conclusion of induction therapy received bevacizumab (10 mg/kg) and paclitaxel (135 mg/m2) q21 days as maintenance therapy. A total of 170 cycles (median = 6; range 3-6) of primary induction chemotherapy, 140 of which contained bevacizumab, were administered. Moreover, 206 cycles (median = 9; range 1-12) of maintenance chemotherapy have been delivered to 28 patients thus far. There was no incidence of GI perforation and only two patients demonstrated clinically significant hypertension. Previous studies involving bevacizumab have raised concerns regarding bowel perforations and hypertension. However, we did not encounter difficulties with either of these complications. While we recognize that the risk for bowel perforation remains in the 5-11% range, the study's preliminary results suggest that first-line treatment of advanced stage ovarian carcinoma with bevacizumab can be safely administered.

A phase II, multicenter trial of weekly topotecan in patients with recurrent platinum-sensitive epithelial cancers of the ovary and peritoneum

The purpose of this study was to evaluate the response rate and toxicity of weekly topotecan in patients with recurrent platinum-sensitive epithelial cancers of the ovary and peritoneum. Thirty-nine platinum-sensitive recurrent ovarian cancer patients received topotecan (4 mg/m2) intravenously day 1, day 8, day 15, every 28 days. Colony-stimulating factors were excluded from the study. Clinical response was assessed by clinical, serologic, and radiographic measures at the conclusion of cycle four. Patients received 136 cycles of topotecan (median = 3; range 1–6) and were evaluated for response and toxicity. Median number of prior regimens was one. Grade 3/4 neutropenia developed in 3 (7.7%) patients. Grade 3 thrombocytopenia was seen in one (2.6%) patient, with no incidence of grade 4 thrombocytopenia. There was no evidence of grade 3 anemia, but one patient (2.6%) was associated with grade 4 anemia. There was no grade 3 or 4 neuropathy. We encountered 18 dose reductions following less than or equal to grade 2 myelosuppression, necessitating the removal of eight (20.5%) patients prior to cycle four. Twenty-one (53.8%) patients were removed from the study due to disease progression. Following the completion of cycle four, four (10.3%) patients demonstrated stable disease and four (10.3%) patients exhibited a partial response. There were no complete responses. Median disease-free survival was 12 weeks. Weekly topotecan (4 mg/m2) demonstrated modest activity and was moderately well tolerated. However, the significant number of dose reductions and high incidence of patients who demonstrated disease progression suggests additional modifications with this specific regimen are necessary.

A phase II study of outpatient first-line paclitaxel, carboplatin, and bevacizumab for advanced-stage epithelial ovarian, peritoneal, and fallopian tube cancer

The purpose of this study was to assess the response rate and toxicity of paclitaxel, carboplatin, and bevacizumab (PCB) primary induction therapy for the treatment of advanced-stage ovarian carcinoma. Twenty patients were treated with paclitaxel (175 mg/m(2)), carboplatin (AUC of 5 IV), and bevacizumab (15 mg/kg) of body weight; q21 days for six cycles. Bevacizumab was administered at cycles two through six. Patients received 116 cycles of PCB chemotherapy (median = 6, range 2-6) and were evaluable for toxicity assessment. Grade 3 and 4 neutropenia developed in 23.3% and 25% of cycles, with no incidence of grades 3/4 thrombocytopenia or anemia. Prior to cycle six, one patient was removed from the study due to grade 3 neuropathy and another patient was excluded due to clinical deterioration. There was no incidence of gastrointestinal perforations, and only two patients demonstrated grade 3 hypertension (HTN). No grade 4 HTN was observed. Eighteen patients were evaluated for response following induction therapy. Six demonstrated a complete response (30%) and ten exhibited a partial response (50%), resulting in a total response rate of 80%. One patient exhibited stable disease (5%), and one demonstrated disease progression (5%). The lack of bowel perforations and wound complications should mitigate some concerns regarding these side effects. This study suggests that first-line treatment with PCB can be safely administered to previously untreated advanced-stage ovarian carcinoma patients. The favorable toxicity results and reasonable response rate warrant additional study in a larger patient population.

Association and colocalization of K+ channel alpha- and beta-subunit polypeptides in rat brain

Recent cloning of auxiliary subunits associated with voltage-gated ion channels and their subsequent coexpression with the channel forming alpha-subunits has revealed that the expression level, gating and conductance properties of the expressed channels can be profoundly affected by the presence of an auxiliary subunit polypeptide. In the present study, we raised antibodies against the beta-subunit associated with the bovine dendrotoxin sensitive K(+)-channel complex and used these antibodies to characterize the related beta-subunit polypeptides in rat brain. The anti-beta-subunit antibodies displayed a specific reaction on immunoblots of rat brain membranes with a major 38 kDa polypeptide, and a minor 41 kDa polypeptide, which correspond closely to the predicted sizes of the Kv beta 2 and Kv beta 1 beta-subunit polypeptides, respectively, recently cloned from rat brain. Reciprocal coimmunoprecipitation experiments revealed that the beta-subunit polypeptides are associated with Kv1.2 and Kv1.4, but not Kv2.1, alpha-subunits. Immunohistochemical staining revealed that the beta-subunit polypeptides were widely distributed in adult rat brain. Moreover, the cellular distribution of beta-subunit immunoreactivity corresponded closely with immunoreactivity for Kv1.2, and to a lesser extent Kv1.4, but not with Kv2.1. These results suggest that neuronal mechanisms may exist to direct the selective interaction of K+ channel alpha- and beta-subunit polypeptides, and that the properties of K+ channels in specific subcellular domains may be regulated by the formation of heteromultimeric K+ channel complexes containing specific combinations of alpha- and beta-subunits.