ABSTRACT
OBJECTIVE: Electroencephalographic (EEG) data are often contaminated with non-neural artifacts which can confound experimental results. Current artifact cleaning approaches often require costly manual input. Our aim was to provide a fully automated EEG cleaning pipeline that addresses all artifact types and improves measurement of EEG outcomes METHODS: We developed RELAX (the Reduction of Electroencephalographic Artifacts). RELAX cleans continuous data using Multi-channel Wiener filtering [MWF] and/or wavelet enhanced independent component analysis [wICA] applied to artifacts identified by ICLabel [wICA_ICLabel]). Several versions of RELAX were compared using three datasets (N = 213, 60 and 23 respectively) against six commonly used pipelines across a range of artifact cleaning metrics, including measures of remaining blink and muscle activity, and the variance explained by experimental manipulations after cleaning. RESULTS: RELAX with MWF and wICA_ICLabel showed amongst the best performance at cleaning blink and muscle artifacts while preserving neural signal. RELAX with wICA_ICLabel only may perform better at differentiating alpha oscillations between working memory conditions. CONCLUSIONS: RELAX provides automated, objective and high-performing EEG cleaning, is easy to use, and freely available on GitHub. SIGNIFICANCE: We recommend RELAX for data cleaning across EEG studies to reduce artifact confounds, improve outcome measurement and improve inter-study consistency.
Subject(s)
Algorithms , Signal Processing, Computer-Assisted , Humans , Blinking , Wavelet Analysis , Electroencephalography/methods , ArtifactsABSTRACT
OBJECTIVE: Electroencephalography (EEG) is often used to examine neural activity time-locked to stimuli presentation, referred to as Event-Related Potentials (ERP). However, EEG is influenced by non-neural artifacts, which can confound ERP comparisons. Artifact cleaning reduces artifacts, but often requires time-consuming manual decisions. Most automated methods filter frequencies <1 Hz out of the data, so are not recommended for ERPs (which contain frequencies <1 Hz). Our aim was to test the RELAX (Reduction of Electroencephalographic Artifacts) pre-processing pipeline for use on ERP data. METHODS: The cleaning performance of multiple versions of RELAX were compared to four commonly used EEG cleaning pipelines across both artifact cleaning metrics and the amount of variance in ERPs explained by different conditions in a Go-Nogo task. Results RELAX with Multi-channel Wiener Filtering (MWF) and wavelet-enhanced independent component analysis applied to artifacts identified with ICLabel (wICA_ICLabel) cleaned data most effectively and produced amongst the most dependable ERP estimates. RELAX with wICA_ICLabel only or MWF_only may detect effects better for some ERPs. CONCLUSIONS: RELAX shows high artifact cleaning performance even when data is high-pass filtered at 0.25 Hz (applicable to ERP analyses). SIGNIFICANCE: RELAX is easy to implement via EEGLAB in MATLAB and freely available on GitHub. Given its performance and objectivity we recommend RELAX to improve artifact cleaning and consistency across ERP research.
Subject(s)
Electroencephalography , Signal Processing, Computer-Assisted , Humans , Electroencephalography/methods , Evoked Potentials/physiology , Algorithms , Wavelet Analysis , ArtifactsABSTRACT
Cultivation of the marine-derived streptomycete isolate B8005 delivered three known antibiotics, resistomycin (1), resistoflavin (3a) and tetracenomycin (4), and a further member of the rare resistomycin class, the weakly antibiotically active 1-hydroxy-1-norresistomycin (2). From a related marine strain B4842, 1 and resistoflavin methyl ether (3b) have been isolated. The formation of 2 is of interest from a biosynthetic point of view.
Subject(s)
Anti-Bacterial Agents/pharmacology , Geologic Sediments/microbiology , Streptomyces/chemistry , Anti-Bacterial Agents/isolation & purification , Benzopyrenes/chemistry , Benzopyrenes/isolation & purification , Benzopyrenes/pharmacokinetics , Benzopyrenes/pharmacology , Ethers/pharmacokinetics , Microbial Sensitivity Tests , Molecular Structure , Pyrenes/pharmacokineticsABSTRACT
Triterpenoid-based scaffolds betulinic acid (1a) and ursolic acid (1b), have been used for the generation of combinatorial libraries in parallel format using solid phase organic synthesis method. These templates have the potential for the synthesis and amplification of triterpenoid-based compounds with one and two-point diversity. This has been demonstrated by the synthesis of two small libraries comprising 18 derivatives each of betulinic acid and ursolic acid with structural diversity at C-3 and C-28 positions. The primary screening of antimalarial activity of these libraries against P. falciparum in vitro led to the identification of four compounds with 5 fold increase in the activity compared to betulinic and ursolic acids.
Subject(s)
Antimalarials/chemical synthesis , Combinatorial Chemistry Techniques , Terpenes/chemical synthesis , Animals , Antimalarials/pharmacology , Drug Evaluation, Preclinical , Indicators and Reagents , Oxidation-Reduction , Oximes , Pentacyclic Triterpenes , Plasmodium falciparum/drug effects , Resins, Plant , Terpenes/pharmacology , Triterpenes/chemistry , Betulinic Acid , Ursolic AcidABSTRACT
2-[Methyl-(3-phenylpropionyl)amino]-benzoic acid (1e) was isolated from a culture of marine Streptomyces sp. strain B7747. Analogous compounds have potential importance as phytotoxic substances, hence compound 1e and the analogues 1a approximately 1d and 1f approximately 3a were synthesised. Antimicroalgal activity of the anthranilamide analogues showed that esters 1b, 1f and 2b were more active than the free acids. The minimum inhibitory concentration (MIC) against Chlorella vulgaris, Chlorella sorokiniana, Chlorella salina and Scenedesmus subspicatus ranged from 20 to 107 micrograms/ml. All anthranilamides were inactive against Staphylococcus aureus, Escherichia coli, and Mucor miehei.
