Voluntary Blinks Research Articles

Perceiving a continuous visual world across voluntary eye blinks.

People blink their eyes every few seconds, but the changes in retinal illumination that accompany eyeblinks are hardly noticed. Furthermore, despite the loss of visual input, visual experience remains continuous across eyeblinks. Two hypotheses were investigated to account for these phenomena. The first proposes that perceptual information is maintained across a blink whereas the second proposes that perceptual information is not maintained but rather postblink perceptual experience is antedated to the beginning of the blink. Two experiments found no evidence for temporal antedating of a stimulus presented during a voluntary eyeblink. In a third experiment subjects judged the temporal duration of a stimulus that was interrupted by a voluntary eyeblink with that of a stimulus presented while the eyes were open. The duration of stimuli that were interrupted by eyeblinks was judged to be 117 ms shorter than that of stimuli presented while the eyes remained open, indicating that blink duration was not accounted for in the perception of stimulus duration. This suggests that perceptual experience is neither maintained nor antedated across eyeblinks, but rather is ignored, perhaps in response to the extraretinal signal that accompanies the eyeblink. (PsycINFO Database Record

2種類の随意性瞬目と自発性瞬目の自動識別法

2種類の随意性瞬目と自発性瞬目の自動識別法

비접촉 눈 깜박임 측정 안경형 디바이스를 이용한 실시간 스펠러의 구현

Abstract: We proposed blink based online speller for the locked-in syndrome (LIS) patients, paralyzed in nearly allvoluntary muscles expect for the eyes, with a simple and easy-to-use eye blink detection glasses. Electrooculogram(EOG) is the golden standard method of eye movement or blink measurement with Ag/AgCl electrodes. However,this method has several drawbacks such as skin irritation and dehydration of conductive gel. To resolve the short-comings, we used a blink detection system based on a transparent capacitively coupled electrode, which is conductiveindium tin oxide (ITO) films. The films make it possible to measure eye blink without direct skin contact and obstruc-tion of field of view. We finally developed user-friendly blink based online speller with the blink detection system.To classify voluntary and non-voluntary blink, we used the double blink for command of the speller. The online spellerexperiment result with six healthy subjects shows that mean accuracy is 98.96% and letter per minute (LPM) is 4.73,which are better result by comparison with conventional P300 or auditory brain-computer interface (BCI) paradigm.The result of the experiment demonstrates the possibility of applying the proposed system as a communicationmethod for the LIS patients.Key words: Wearable device, ITO film, Blink, Human-Computer Interface, speller

Eyelid transplantation: lessons from a total face transplant and the importance of blink.

Despite inclusion of periorbital structures in facial transplants, critical assessment of posttransplantation short- and long-term periorbital function has not been reported. The purpose of this article is to report recovery of ocular and periorbital function, with critical appraisal of posttransplant blink in the setting of revision surgery. Prospective ocular and periorbital functional assessments were completed at multiple time points in a patient undergoing facial transplantation and subsequent revision operations. Function was evaluated using clinical ocular examinations, visual acuity assessments, photography, and video at various intervals from preoperative baseline to 13.5 months after transplantation. During this period, revision operations involving periorbital structures were performed at 6 and 9 months after transplantation. Before transplantation, volitional blink was 100 percent in both eyes. Involuntary blink was 40 percent in the right eye and 90 percent in the left eye, with occasional full closure. Following face transplantation, voluntary blink was preserved, partial skin sensation was present, and involuntary blink improved to 70 percent in the right eye and 100 percent in the left eye. Following revision surgery, visual acuity and voluntary and involuntary blink were impaired. By 7.5 months after revision, improvement comparable to the pretransplantation assessment was observed. Adherence to principles of blink preservation is critical in periorbital transplantation. Involuntary blink is essential for preserving vision, and can be improved after transplantation. Revision surgery may temporarily impair advances made with initial allotransplantation. A comprehensive understanding of ocular biomechanics and function is invaluable to the reconstructive surgeon performing facial transplantation involving periorbital structures and posttransplant revision operations. Therapeutic, V.

Withdrawal of voluntary inhibition unravels the off state of the spontaneous blink generator

Involuntary movements such as spontaneous eye blinks can be successfully inhibited at will. Little do we know how the voluntary motor circuits countermand spontaneous blinks. Do the voluntary inhibitory commands act to pause or to turn off the endogenous blink generator, or does inhibition intersect and counter the generator׳s excitatory outputs? In theory, the time taken for the system to generate an after-inhibition blink will reflect onto the form of inhibition. For instance, if voluntary commands were to turn the blink generator off then the after-blink latency would be fixed to the inhibition offset and reflect the time it takes for the generator to rebound and turn on. In this study we measured the after-blink latency from the offset of voluntary inhibition. Volunteers inhibited their blinks in response to sound tones of randomly varying durations. At the offset volunteers withdrew the inhibition and relaxed. Interestingly, the spontaneous after-blinks were fixed to the offset of the inhibition as if the generator rebounded from an off state. The after-blink latency was not related to the duration of the inhibition, and inhibiting even for a small fraction of the mean inter-blink interval generated an after-blink time-locked to the inhibition offset. Interestingly, the insertion of voluntary blinks after inhibition further altered the blink generator by delaying the spontaneous after-blinks. We propose that the inhibition of spontaneous blinks at the level of the generator allows for highly effective voluntary countermanding. Nevertheless, the withdrawal of such inhibition was strongly associated with motor excitation.

Removing artefacts from TMS-EEG recordings using independent component analysis: Importance for assessing prefrontal and motor cortex network properties

IntroductionThe combination of transcranial magnetic stimulation and electroencephalography (TMS-EEG) is emerging as a powerful tool for causally investigating cortical mechanisms and networks. However, various artefacts contaminate TMS-EEG recordings, particularly over regions such as the dorsolateral prefrontal cortex (DLPFC). The aim of this study was to substantiate removal of artefacts from TMS-EEG recordings following stimulation of the DLPFC and motor cortex using independent component analysis (ICA). Methods36 healthy volunteers (30.8±9years, 9 female) received 75 single TMS pulses to the left DLPFC or left motor cortex while EEG was recorded from 57 electrodes. A subset of 9 volunteers also received 50 sham pulses. The large TMS artefact and early muscle activity (−2 to ~15ms) were removed using interpolation and the remaining EEG signal was processed in two separate ICA runs using the FastICA algorithm. Five sub-types of TMS-related artefacts were manually identified: remaining muscle artefacts, decay artefacts, blink artefacts, auditory-evoked potentials and other noise-related artefacts. The cause of proposed blink and auditory-evoked potentials was assessed by concatenating known artefacts (i.e. voluntary blinks or auditory-evoked potentials resulting from sham TMS) to the TMS trials before ICA and evaluating grouping of resultant independent components (ICs). Finally, we assessed the effect of removing specific artefact types on TMS-evoked potentials (TEPs) and TMS-evoked oscillations. ResultsOver DLPFC, ICs from proposed muscle and decay artefacts correlated with TMS-evoked muscle activity size, whereas proposed TMS-evoked blink ICs combined with voluntary blinks and auditory ICs with auditory-evoked potentials from sham TMS. Individual artefact sub-types characteristically distorted each measure of DLPFC function across the scalp. When free of artefact, TEPs and TMS-evoked oscillations could be measured following DLPFC stimulation. Importantly, characteristic TEPs following motor cortex stimulation (N15, P30, N45, P60, N100) could be recovered from artefactual data, corroborating the reliability of ICA-based artefact correction. ConclusionsVarious different artefacts contaminate TMS-EEG recordings over the DLPFC and motor cortex. However, these artefacts can be removed with apparent minimal impact on neural activity using ICA, allowing the study of TMS-evoked cortical network properties.

Online Voluntary Eye Blink Detection using Electrooculogram

This paper describes the voluntary eye blink detection method using electrooculogram (EOG). There are still challenge problems to put brain-computer interfa ce (BCI) systems to real-life applications. In general BCI sys- tems, there is a possibility of incorrect and unintentional input because input is automatically selected even if the requirements are accidentally met. This study aims to pro- pose the voluntary eye blink detection method and apply it to the trigger switch of BCI systems. In the proposed method, normal blink, double blink, and wink can be de- tected from vertical and horizontal EOG signals. We em- ployed the positive peak of vertical and horizontal ampli- tude and maximum cross correlation coeffi cient between vertical EOG and template signal of double blink in feature extraction. Eye blinks were classified by support vector machine. As the result of simulations, an average accuracy of 97.28% was obtained using our method. In addition, the best accuracy for voluntary eye blinks was obtained for wink with accuracy of 97.69 %. This paper proof wink is suitable for trigger switch of BCI system, and online method for voluntary eye blink detection.

Driving Control of a Powered Wheelchair by Voluntary Eye Blinking and with Environment Recognition

This paper describes the driving control system for a powered wheelchair using voluntary eye blinks. Recently, new human-computer interfaces (HCIs) that take the place of a joystick have been developed for people with disabilities of the upper body. In this paper, voluntary eye blinks are used as an HCI. However, the problem with this HCI is that the number of input directions and operations is smaller than that of a joystick, which causes inefficient movement. Therefore, assistive systems are needed for efficient and safe wheelchair movement. The proposed system is based on environment recognition and fuzzy logic. It can detect obstacles and passages, and speed and direction are calculated automatically for obstacle avoidance and right/left turns. The systems effectiveness is demonstrated through experiments with a real HCI in a real environment.

Calculate Target Position of Object in 3-Dimensional Area Based on the Perceived Locations Using EOG Signals

EOG is a biosignal which occurs during eye activities such as eye movement and blink. EOG has a linear relationship with gaze distance. Detection object position in 3-dimensional area using gaze motion was proposed in this research. To calculate the distance of gaze motion in pixel unit, affine transform method was developed. The homogeneous matrix from five geometry processes: transformation-1, rotation, transformation-2, shear, and dilatation was determined. To give tracking ability in 3-dimensional area, two cameras were attached each in front of and top side of object. The cameras were accessed by voluntary blink. The EOG characteristic of blink eye was determined based on the absolute ratio between positive peak and negative peak which was greater than 1. Every blink toggled the active camera. The position of object was given by the perceived locations from the two cameras. Every movement in pixel coordinate was converted into centimeter unit. Then, the perceived location was used to calculate to the base coordinate. The result shows that the blink method successfully accessed the camera. Both of the cameras could show the location of object from their side. Calculating the gaze distance using affine transform also gave a satisfied result. Using this method controlling a machine in 3-dimensional area by EOG could be developed.

随意性瞬目を用いた2リンク型ロボットアームの先端位置制御コントローラの開発

随意性瞬目を用いた2リンク型ロボットアームの先端位置制御コントローラの開発

Research of peraotion method of accessibility equipment based on voluntary eye blink

Research of peraotion method of accessibility equipment based on voluntary eye blink

Classification of Blink Type by a Frame Splitting Method using Hi-Vision Image

Recently, the human-machine interface using information of user's eye blink was reported. This system operates a personal computer in real-time. Eye blinks can be classified into voluntary (conscious) blinks and involuntary (unconscious) blinks. If the voluntary blinks can be distinguished in automatic, an input decision can be made when user's voluntary blinks occur. By using this system, the usability of input is increased. We have proposed a new eye blink detection method that uses a Hi-Vision video camera. This method utilizes split interlace images of the eye. These split images are odd- and even- field images in the 1080i Hi-Vision format and are generated from interlaced images. The proposed method yields a time resolution that is double that in the 1080i Hi-Vision format. We refer to this approach as a “frame-splitting method”. We also proposed a method for automatic eye blink extraction using this method. The extraction method is capable of classifying the start and end points of eye blinks. In other words, the feature parameters of voluntary and involuntary blinks can be measured by this extraction method. In this paper, we propose a new classification method for eye blink types using these feature parameters.

Voluntary Eye Blink Detection Using Electrooculogram for Controlling Powered Wheelchairs Considering Environmental Information

This paper describes the voluntary eye blink detection method using electrooculogram (EOG) for controlling a powered wheelchair. This study aims to apply double blink, left and right wink to control commands for a powered wheelchair such as go/stop, left and right turn. Our previous study showed that these eye blinks can be detected by using EOG and classification models specialized for individuals. Therefore, the persons who are not registered cannot use this system because the amplitude of EOG has an individual difference. In this study, we proposed the voluntary eye blink detection method that has robustness for individual difference of EOG amplitude by using correlation coefficient with template signal. As the result of simulations, an averaged accuracy of 98.05% was obtained, and the efficacy of powered wheelchair applied the proposed method was confirmed.

A BOLD signature of eyeblinks in the visual cortex

We are usually unaware of the brief but large illumination changes caused by blinks, presumably because of blink suppression mechanisms. In fMRI however, increase of the BOLD signal was reported in the visual cortex, e.g. during blocks of voluntary blinks (Bristow, Frith and Rees, 2005) or after spontaneous blinks recorded during the prolonged fixation of a static stimulus (Tse, Baumgartner and Greenlee, 2010). We tested whether such activation, possibly related to illumination changes, was also present during standard fMRI retinotopic and visual experiments and was large enough to contaminate the BOLD signal we are interested in. We monitored in a 3T scanner the eyeblinks of 14 subjects who observed three different types of visual stimuli, including periodic rotating wedges and contracting/expanding rings, event-related Mondrians and graphemes, while fixating. We performed event-related analyses on the set of detected spontaneous blinks. We observed large and widespread BOLD responses related to blinks in the visual cortex of every subject and whatever the visual stimulus. The magnitude of the modulation was comparable to visual stimulation. However, blink-related activations lay mostly in the anterior parts of retinotopic visual areas, coding the periphery of the visual field well beyond the extent of our stimuli. Blinks therefore represent an important source of BOLD variations in the visual cortex and a troublesome source of noise since any correlation, even weak, between the distribution of blinks and a tested protocol could trigger artifactual activities. However, the typical signature of blinks along the anterior calcarine and the parieto-occipital sulcus allows identifying, even in the absence of eyetracking, fMRI protocols possibly contaminated by a heterogeneous distribution of blinks.

Effects of subthalamic nucleus deep brain stimulation and l-dopa on blinking in Parkinson's disease

In this study we asked whether subthalamic nucleus deep brain stimulation (STN-DBS) alone, or in combination with l-dopa, modifies voluntary, spontaneous and reflex blinking in patients with Parkinson's disease (PD). Sixteen PD patients who underwent STN-DBS were studied in four experimental conditions: without STN-DBS and without l-dopa, STN-DBS alone, l-dopa alone and STN-DBS plus l-dopa. The results were compared with those obtained in 15 healthy controls. Voluntary blinking was assessed by asking participants to blink as fast as possible; spontaneous blinking was recorded during two 60s rest periods; reflex blinking was evoked by electrical stimulation of the supraorbital nerve. Blinking were recorded and analysed with the SMART motion system. STN-DBS increased the peak velocity and amplitude for both the closing and opening voluntary blink phases, but prolonged the inter-phase pause duration. l-dopa had no effects on voluntary blinking but reversed the increased inter-phase pause duration seen during STN-DBS. Spontaneous blink rate increased after either STN-DBS or l-dopa. Reflex blinking kinematics were not modified by STN-DBS or l-dopa. The STN-DBS effects on voluntary blinking kinematics and spontaneous blinking rate may occur as results of changes of cortico-basal ganglia activity. The prolonged pause duration of voluntary blinking indicates that STN-DBS has detrimental effects on the cranial region. These results also shed light on the pathophysiology of eyelids opening apraxia following STN-DBS.

Human-Computer Interface Controlled by Horizontal Directional Eye Movements and Voluntary Blinks Using AC EOG Signals

Human-Computer Interface Controlled by Horizontal Directional Eye Movements and Voluntary Blinks Using AC EOG Signals

Implementation of a robust absolute virtual head mouse combining face detection, template matching and optical flow algorithms

This work proposes the implementation of a robust absolute virtual head mouse based on the interpretation of head movements and face gestures captured with a frontal camera. The procedure combines face detection, template matching and optical flow algorithms to emulate all mouse events. This virtual device is designed specifically as an alternative non-contact pointer for people with mobility impairments in the upper extremities. The implementation of the virtual mouse was compared with a standard mouse, a touchpad and a joystick. Validation results show motion performances comparable to those of a standard mouse and better than those of a joystick in addition to good performances when detecting face gestures to generate click events: 96% success in the case of opening the mouth and 68% in the case of voluntary eye blinks.

Electrooculogram Detection of Eye Movements on Gaze Displacement

Changes in potential are known to occur in the orbital area during saccades. The sign of these changes depends on the position of the electrode and the direction of eye rotation, while their amplitude depends on the rotation angle. The patterns of potentials can be used to resolve the reverse task, i.e., that of describing the gaze trajectory, such that the eye can be used to control a computer in an on-line regime. This requires a screen cursor to be placed at the calculated gaze fixation point, i.e., the point at which the observer is looking. Electrodes beneath the eyes were used to assess the vertical component of gaze displacement, while side electrodes at the corners of the orbit were used to assess the horizontal component. Sharp unipolar changes in potential occurring on saccades were apparent as steps which could be detected and measured. The signal was digitally filtered using a complex filter constructed by ourselves. The ratio of the amplitudes at the four points was then used to calculate the direction and angle of eye rotation. Characteristic changes in potential during spontaneous blinking were identified and ignored. Voluntary blinks of one eye were used to simulate mouse clicks. Subjects were initially told to make changes in gaze through specified angles in eight directions. This allowed calibration of standard saccades (in microV). Calibration curves were used to resolve the reverse task - changes in potential (in microV) were used to calculate the point on the screen (the pixel) to which the cursor was to be moved. Subjects were then trained to control the cursor using their eyes, and control of the computer was then completely handed over to the subject. The apparatus described here provides a brain-computer interface. Some interesting data on eye coordination were obtained during these studies: saccades were preceded by short negative electrooculogram (EOG) potentials lasting 10-15 msec. With age, the amplitude of saccade-related EOG potentials decreased. When gaze was shifted to the left, deviation of the eyes was more significant than when gaze was shifted to the right, while on shifting of gaze to the right, the lateral deviations of the eyes were similar. On diagonal right-down and left-up movements, right eye skew was greater than left eye skew, while on right-up and left-down movements, left eye skew was greater than right eye skew. Differences in eye coordination between genders were minor.

Eye-blinks and tracking

Visual Indexing Theory proposes a referential mechanism that tracks objects in a visual scene without necessarily encoding object properties, as demonstrated through Multiple Object Tracking experiments. The encoding of location information during object tracking, however, remains a possible exception. In the current studies, we tracked eye movements during a standard MOT task and employed a blink-contingent methodology in which objects stopped moving or disappeared during eye-blinks. Because this halting is synchronized with eye-blinks, we were able to examine natural, intrinsically generated disruptions of the visual scene without inadvertently cuing the object change. Experiment 1 examined the effect of changes in object motion that occurred during spontaneous eye-blinks. Subjects performed a standard MOT task (4 targets, 8 non-targets). In half the trials, the objects halted for the duration of all blinks; these trials were randomized among trials where objects continued their movement. The results indicate that a blink-contingent halting of objects produces fewer tracking errors, but this effect diminishes with practice. Also, fewer fixations were correlated with better tracking performance in the last block. Experiment 2 tested for location-encoding during MOT when objects disappeared during more natural interruptions (instead of occlusions or abrupt disappearances). We replicated the main features of Keane & Pylyshyn (2006) except we replaced occlusions with blink-contingent disappearances. We used a simple sound to signal subjects to blink once during each trial. This voluntary blink induced a change in object motion (halting or continuing along trajectories) and disappearance (150, 300, 450, or 900 ms). The results revealed superior tracking performance in the halt conditions, with lower performance as disappearance duration increased in both conditions. Overall, our results suggest that location information and trajectory extrapolation are not crucial for tracking. When abrupt changes in a scene are visually detected, the most recently sampled location may be retrieved.

Research of the Switch Operation by Voluntary Blinks Utilizing EOG

Research of the Switch Operation by Voluntary Blinks Utilizing EOG