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Automatic eye blink artifact removal for EEG based on a sparse coding technique for assessing major mental disorders

Zafar R, Qayyum A, Mumtaz W

J Integr Neurosci, 2019 Sep 30;18(3):217-229.
PMID: 31601069 DOI: 10.31083/j.jin.2019.03.164

In the electroencephalogram recorded data are often confounded with artifacts, especially in the case of eye blinks. Different methods for artifact detection and removal are discussed in the literature, including automatic detection and removal. Here, an automatic method of eye blink detection and correction is proposed where sparse coding is used for an electroencephalogram dataset. In this method, a hybrid dictionary based on a ridgelet transformation is used to capture prominent features by analyzing independent components extracted from a different number of electroencephalogram channels. In this study, the proposed method has been tested and validated with five different datasets for artifact detection and correction. Results show that the proposed technique is promising as it successfully extracted the exact locations of eye blinking artifacts. The accuracy of the method (automatic detection) is 89.6% which represents a better estimate than that obtained by an extreme machine learning classifier.

Matched MeSH terms: Blinking
The impact of cognitive load on reward evaluation

Krigolson OE, Hassall CD, Satel J, Klein RM

Brain Res, 2015 Nov 19;1627:225-32.
PMID: 26431993 DOI: 10.1016/j.brainres.2015.09.028

The neural systems that afford our ability to evaluate rewards and punishments are impacted by a variety of external factors. Here, we demonstrate that increased cognitive load reduces the functional efficacy of a reward processing system within the human medial-frontal cortex. In our paradigm, two groups of participants used performance feedback to estimate the exact duration of one second while electroencephalographic (EEG) data was recorded. Prior to performing the time estimation task, both groups were instructed to keep their eyes still and avoid blinking in line with well established EEG protocol. However, during performance of the time-estimation task, one of the two groups was provided with trial-to-trial-feedback about their performance on the time-estimation task and their eye movements to induce a higher level of cognitive load relative to participants in the other group who were solely provided with feedback about the accuracy of their temporal estimates. In line with previous work, we found that the higher level of cognitive load reduced the amplitude of the feedback-related negativity, a component of the human event-related brain potential associated with reward evaluation within the medial-frontal cortex. Importantly, our results provide further support that increased cognitive load reduces the functional efficacy of a neural system associated with reward processing.

Matched MeSH terms: Blinking
Predicted effect compartment concentration of thiopental at loss of eyelash reflex

Lim TA, Inbasegaran K

Br J Anaesth, 2001 Mar;86(3):422-4.
PMID: 11573534

We derived the predicted effect compartment concentration of thiopental, at loss of the eyelash reflex, following three different injection regimens. Sixty patients were given thiopental for induction of anaesthesia. Twenty patients received multiple small boluses, 20 patients received a single bolus and 20 patients received an infusion. Computer simulation was then used to derive the effect compartment concentration. The median concentration was not significantly different between the three groups. EC50, derived after combining all three groups was 11.3 microg ml(-1). The EC05-EC95 range was 6.9-18.3 microg ml(-1), suggesting wide inter-individual variation.

Matched MeSH terms: Blinking/drug effects*
A novel method of deriving the effect compartment equilibrium rate constant for propofol

Lim TA

Br J Anaesth, 2003 Nov;91(5):730-2.
PMID: 14570797

BACKGROUND: Calculation of the effect compartment concentration (Ce) in non-steady-state conditions requires the equilibrium rate constant, keo. Most studies of propofol derive the keo using EEG measurements. This study investigated an alternative method. Starting from a predicted concentration-time profile, a keo value was included so that the predicted Ce at a specific pharmacodynamic end-point was the same when using three different methods of injection.
METHODS: Seventy-five patients were given propofol for induction of anaesthesia. Twenty-five patients received a single bolus, 25 patients received an infusion, and 25 patients received a bolus followed by an infusion. Computer simulation was used to derive the central compartment concentration. The keo that brought about the same value for Ce at loss of the eyelash reflex using the three methods of injection was derived.
RESULTS: Keo was found to be 0.80 min(-1). Mean (SD) Ce at loss of the eyelash reflex was 2.27 (0.69) microg ml(-1).
CONCLUSIONS: The effect compartment equilibrium rate constant and concentration at loss of the eyelash reflex can be derived without the use of electronic central nervous system monitors.

Matched MeSH terms: Blinking/drug effects
Fulltext Gap-induced inhibition of the post-auricular muscle response in humans and guinea pigs

Wilson CA, Berger JI, de Boer J, Sereda M, Palmer AR, Hall DA, et al.

Hear Res, 2019 03 15;374:13-23.
PMID: 30685571 DOI: 10.1016/j.heares.2019.01.009

A common method for measuring changes in temporal processing sensitivity in both humans and animals makes use of GaP-induced Inhibition of the Acoustic Startle (GPIAS). It is also the basis of a common method for detecting tinnitus in rodents. However, the link to tinnitus has not been properly established because GPIAS has not yet been used to objectively demonstrate tinnitus in humans. In guinea pigs, the Preyer (ear flick) myogenic reflex is an established method for measuring the acoustic startle for the GPIAS test, while in humans, it is the eye-blink reflex. Yet, humans have a vestigial remnant of the Preyer reflex, which can be detected by measuring skin surface potentials associated with the Post-Auricular Muscle Response (PAMR). A similar electrical potential can be measured in guinea pigs and we aimed to show that the PAMR could be used to demonstrate GPIAS in both species. In guinea pigs, we compare the GPIAS measured using the pinna movement of the Preyer reflex and the electrical potential of the PAMR to demonstrate that the two are at least equivalent. In humans, we establish for the first time that the PAMR provides a reliable way of measuring GPIAS that is a pure acoustic alternative to the multimodal eye-blink reflex. Further exploratory tests showed that while eye gaze position influenced the size of the PAMR response, it did not change the degree of GPIAS. Our findings confirm that the PAMR is a sensitive method for measuring GPIAS and suggest that it may allow direct comparison of temporal processing between humans and animals and may provide a basis for an objective test of tinnitus.

Matched MeSH terms: Blinking/physiology
Effects of wink glass on blink rate, nibut and ocular surface symptoms during visual display unit use

Ang CK, Mohidin N, Chung KM

Curr Eye Res, 2014 Sep;39(9):879-84.
PMID: 25014251 DOI: 10.3109/02713683.2013.859273

PURPOSE/AIM: Wink glass (WG), an invention to stimulate blinking at interval of 5 s was designed to reduce dry eye symptoms during visual display unit (VDU) use. The objective of this study is to investigate the effect of WG on visual functions that include blink rate, ocular surface symptoms (OSS) and tear stability during VDU use.
MATERIALS AND METHODS: A total of 26 young and asymptomatic subjects were instructed to read articles in Malay language with a computer for 20 min with WG whereby their blink rate, pre- and post-task tear break-up time, and OSS were recorded. The results were compared to another reading session of the subjects wearing a transparent plastic sheet as a control.
RESULTS: Non-invasive tear break-up time was reduced after reading session with transparent plastic sheet (pre-task = 5.97 s, post-task = 5.14 s, z = -2.426, p = 0.015, Wilcoxon), but remained stable (pre-task = 5.62 s, post-task = 5.35 s, z = -0.67, p = 0.501) during the reading session with WG. The blink rate recorded during reading session with plastic sheet was 9 blinks/min (median) and this increased to 15 blinks/min (z = -3.315, p = 0.001) with WG. The reading task caused OSS (maximum scores = 20) with median score of 1 (0-8) reduced to median score of 0 (0-3) after wearing WG (z = -2.417, p = 0.016).
CONCLUSION: WG was found to increase post-task tear stability, increased blinking rate and reduced OSS during video display unit use among young and healthy adults. Although it may be considered as an option to improve dry eye symptoms among VDU users, further studies are warranted to establish its stability and its effect on subjects with dry eyes.
KEYWORDS: Blink rate; Wink glass; non-invasive tear break-up time; visual display units

Matched MeSH terms: Blinking/physiology*