Examination of Driver Visual and Cognitive Responses to Billboard Elicited Passive Distraction Using Eye-Fixation Related Potential.

Distractions external to a vehicle contribute to visual attention diversion that may cause traffic accidents. As a low-cost and efficient advertising solution, billboards are widely installed on side of the road, especially the motorway. However, the effect of billboards on driver distraction, eye gaze, and cognition has not been fully investigated. This study utilises a customised driving simulator and synchronised electroencephalography (EEG) and eye tracking system to investigate the cognitive processes relating to the processing of driver visual information. A distinction is made between eye gaze fixations relating to stimuli that assist driving and others that may be a source of distraction. The study compares the driver's cognitive responses to fixations on billboards with fixations on the vehicle dashboard. The measured eye-fixation related potential (EFRP) shows that the P1 components are similar; however, the subsequent N1 and P2 components differ. In addition, an EEG motor response is observed when the driver makes an adjustment of driving speed when prompted by speed limit signs. The experimental results demonstrate that the proposed measurement system is a valid tool in assessing driver cognition and suggests the cognitive level of engagement to the billboard is likely to be a precursor to driver distraction. The experimental results are compared with the human information processing model found in the literature.

Design of a novel photosensitive phantom for the accurate calibration of the temporal response of electroencephalography systems.

This paper describes a novel method to measure the temporal latency of electroencephalography (EEG) systems using a customized photosensitive phantom. The system was evaluated with three different EEG devices, a medical grade (g.Tec), a consumer grade (Emotiv), and a low-cost device (Arduino SpikerShield). The temporal latencies of the three EEG devices were measured. The proposed method can be easily adapted to assess other EEG devices. The measurements obtained in this experiment provided concrete data for future experiments where accurate timing data are critical.

Weakly supervised training of a sign language recognition system using multiple instance learning density matrices.

A system for automatically training and spotting signs from continuous sign language sentences is presented. We propose a novel multiple instance learning density matrix algorithm which automatically extracts isolated signs from full sentences using the weak and noisy supervision of text translations. The automatically extracted isolated samples are then utilized to train our spatiotemporal gesture and hand posture classifiers. The experiments were carried out to evaluate the performance of the automatic sign extraction, hand posture classification, and spatiotemporal gesture spotting systems. We then carry out a full evaluation of our overall sign spotting system which was automatically trained on 30 different signs.

Alcohol affects otolith-induced ocular counterrolling: dosage effects.

CONCLUSION: Otolith function is significantly affected by alcohol ingestion and the higher the dosage, the greater the effect. OBJECTIVE: To determine how the effect of a 5 oz (150 ml) dose of alcohol differs from an earlier study examining the effect of 3 oz (90 ml) on ocular counterrolling (OCR). SUBJECTS AND METHODS: Twenty subjects underwent OCR testing before and after drinking 5 oz of 80 proof vodka. RESULTS: Blood alcohol levels (BAL) of the subjects ranged from 0.09 to 0.18%. Three measures of OCR were considered. Amplitude was significantly reduced post-alcohol; disconjugacy was significantly increased post-alcohol; smoothness was not significantly different pre- and post-alcohol. In contrast, the lower 3 oz study produced BAL of 0.04-0.09% and resulted in significantly reduced OCR amplitude, no significant change in disconjugacy, but a significant improvement in smoothness. The increase in BAL produced further impairment of amplitude and conjugacy but eliminated the benefit of smoothness.

Software platform for rapid prototyping of NIRS brain computer interfacing techniques.

This paper describes the control system of a next-generation optical brain-computer interface (BCI). Using functional near-infrared spectroscopy (fNIRS) as a BCI modality is a relatively new concept, and research has only begun to explore approaches for its implementation. It is necessary to have a system by which it is possible to investigate the signal processing and classification techniques available in the BCI community. Most importantly, these techniques must be easily testable in real-time applications. The system we describe was built using LABVIEW, a graphical programming language designed for interaction with National Instruments hardware. This platform allows complete configurability from hardware control and regulation, testing and filtering in a graphical interface environment.

Development of a wearable motion capture suit and virtual reality biofeedback system for the instruction and analysis of sports rehabilitation exercises.

This paper describes the design and development of a computer game for instructing an athlete through a series of prescribed rehabilitation exercises. In an attempt to prevent or treat musculoskeletal type injuries along with trying to improve physical performance, athletes are prescribed exercise programmes by appropriately trained specialists. Typically athletes are shown how to perform each exercise in the clinic following examination but they often have no way of knowing if their technique is correct while they are performing their home exercise programme. We describe a system that allows an automatic audit of this activity. Our system utilises ten inertial motion tracking sensors incorporated in a wearable body suit which allows a bluetooth connection from a root hub to a laptop/computer. Using our specifically designed software programme, the athlete can be instructed and analysed as he/she performs the individually tailored exercise programme and a log is recorded of the time and performance level of each exercise completed. We describe a case study that illustrates how a clinician can at a later date review the athletes progress and subsequently alter the exercise programme as they see fit.

Brain-computer interface using a simplified functional near-infrared spectroscopy system.

A brain-computer interface (BCI) is a device that allows a user to communicate with external devices through thought processes alone. A novel signal acquisition tool for BCIs is near-infrared spectroscopy (NIRS), an optical technique to measure localized cortical brain activity. The benefits of using this non-invasive modality are safety, portability and accessibility. A number of commercial multi-channel NIRS system are available; however we have developed a straightforward custom-built system to investigate the functionality of a fNIRS-BCI system. This work describes the construction of the device, the principles of operation and the implementation of a fNIRS-BCI application, 'Mindswitch' that harnesses motor imagery for control. Analysis is performed online and feedback of performance is presented to the user. Mindswitch presents a basic 'on/off' switching option to the user, where selection of either state takes 1 min. Initial results show that fNIRS can support simple BCI functionality and shows much potential. Although performance may be currently inferior to many EEG systems, there is much scope for development particularly with more sophisticated signal processing and classification techniques. We hope that by presenting fNIRS as an accessible and affordable option, a new avenue of exploration will open within the BCI research community and stimulate further research in fNIRS-BCIs.

Noncontact simultaneous dual wavelength photoplethysmography: a further step toward noncontact pulse oximetry.

We present a camera-based device capable of capturing two photoplethysmographic (PPG) signals at two different wavelengths simultaneously, in a remote noncontact manner. The system comprises a complementary metal-oxide semiconductor camera and dual wavelength array of light emitting diodes (760 and 880 nm). By alternately illuminating a region of tissue with each wavelength of light, and detecting the backscattered photons with the camera at a rate of 16 frames/wavelength s, two multiplexed PPG wave forms are simultaneously captured. This process is the basis of pulse oximetry, and we describe how, with the inclusion of a calibration procedure, this system could be used as a noncontact pulse oximeter to measure arterial oxygen saturation (S(p)O(2)) remotely. Results from an experiment on ten subjects, exhibiting normal S(p)O(2) readings, that demonstrate the instrument's ability to capture signals from a range of subjects under realistic lighting and environmental conditions are presented. We compare the signals captured by the noncontact system to a conventional PPG signal captured concurrently from a finger, and show by means of a J. Bland and D. Altman [Lancet 327, 307 (1986); Statistician 32, 307 (1983)] test, the noncontact device to be comparable to a contact device as a monitor of heart rate. We highlight some considerations that should be made when using camera-based "integrative" sampling methods and demonstrate through simulation, the suitability of the captured PPG signals for application of existing pulse oximetry calibration procedures.

A concept for extending the applicability of constraint-induced movement therapy through motor cortex activity feedback using a neural prosthesis.

This paper describes a concept for the extension of constraint-induced movement therapy (CIMT) through the use of feedback of primary motor cortex activity. CIMT requires residual movement to act as a source of feedback to the patient, thus preventing its application to those with no perceptible movement. It is proposed in this paper that it is possible to provide feedback of the motor cortex effort to the patient by measurement with near infrared spectroscopy (NIRS). Significant changes in such effort may be used to drive rehabilitative robotic actuators, for example. This may provide a possible avenue for extending CIMT to patients hitherto excluded as a result of severity of condition. In support of such a paradigm, this paper details the current status of CIMT and related attempts to extend rehabilitation therapy through the application of technology. An introduction to the relevant haemodynamics is given including a description of the basic technology behind a suitable NIRS system. An illustration of the proposed therapy is described using a simple NIRS system driving a robotic arm during simple upper-limb unilateral isometric contraction exercises with healthy subjects.

Dynamic pitch rotation affects eye torsion.

CONCLUSION: Most of the subjects studied had eye torsion responses to pitch, although the direction of torsion varied between subjects. Opposite responses may be the result of individual variation in anatomical or physiological vector orientations of hair cells in the anterior or posterior utricle or in the saccule. OBJECTIVE: This study aimed to determine whether systematic changes in eye torsion occur when subjects are rotated in forward and backward pitch. MATERIALS AND METHODS: Twenty-one normal subjects were seated in a dual axis human rotator, positioned so that the interaural axis was aligned with the axis of pitch rotation. Fixation LED suppressed vertical or horizontal eye movement. Recordings were carried out in darkness apart from the fixation LED, using a three-dimensional eye tracker based on CMOS image sensors. Subjects were twice tilted from upright to 90 degrees occiput down, then forward to 45 degrees face down. RESULTS: Most subjects had eye torsion changes in response to pitch, with mean amplitudes of approximately 2 degrees to 90 degrees backward tilt and 1 degree to 45 degrees forward tilt. Ten subjects had clockwise torsion to backward pitch and counterclockwise to forward pitch; six subjects had the opposite responses. Statistical testing of the distributions of the regression slopes between these two groups were significant (p<0.001). Five subjects had unclear responses.

The effect of alcohol ingestion on ocular counterrolling.

Nineteen normal subjects underwent two naso-occipital rotations to 90 degrees right and left ear down in our standard ocular counterrolling (OCR) protocol. Both eyes were videotaped. Following two rotations, subjects drank 90 ml vodka in 180 ml orange juice; and in about 20 min, when blood alcohol levels reached 0.04-0.09%, the protocol was repeated. An SMI videooculography system provided measurements. Results showed that amplitude of OCR was significantly decreased after alcohol ingestion; smoothness was significantly increased after alcohol, similar to alcohol's effect on essential tremor. Although disconjugacy was not significantly different in the two conditions when the entire trials were examined, the latter portions of the post-alcohol trials did show significant disconjugacy, similar to earlier findings in vestibular-defective patients whose OCR deficits were apparent only in the final segments of the rotation trials. We postulate the results are due to alcohol's action on cerebellar GABAergic Purkinje cells projecting to vestibular nuclei.

Design and implementation of an end tidal CO2 simulator for the evaluation of clinical gas analysers.

This paper presents a new technique to determine the dynamic and frequency response of capnographs using a custom built 'EtCO2 simulator system'. Capnographs are devices that use CO2 from a patients' expired breath to monitor the cardiopulmonary status during anaesthesia and mechanical ventilation. Capnographs at present are routinely calibrated via a static calibration method only. The dynamic response of the capnographs is not accounted for. The frequency and time response are important as they determine if capnographs can be used in high frequency and pediatric ventilation schemes. Experiments performed using the method described in this paper proved that old capnographs usually do not satisfy the manufacturer quoted specifications for time and frequency response. Therefore, a routine check for capnographs is recommended. The method can also be used to verify manufacturer quoted specifications. The EtCO2 simulator system, designed and constructed simulates human respiration cycle. The gas sources used are 5% CO2 and room air that can be switched alternatively. Both supplies are pressure regulated and connected through non-return valves to electric valves. The valves are microprocessor controlled and the on/off time is user defined allowing a wide range of waveforms to be simulated. The output from the simulator is delivered to capnograph. Capnograms are captured by digital video recording. The captured video in 'avi' file format is then converted into individual frames. These frames are converted into digital data through image processing in Matlab. The data obtained is subjected to extensive analysis to determine the frequency and time response of the respective capnograph.

On the suitability of near-infrared (NIR) systems for next-generation brain-computer interfaces.

A brain-computer interface (BCI) gives those suffering from neuromuscular impairments a means to interact and communicate with their surrounding environment. A BCI translates physiological signals, typically electrical, detected from the brain to control an output device. A significant problem with current BCIs is the lengthy training periods involved for proficient usage, which can often lead to frustration and anxiety on the part of the user. Ultimately this can lead to abandonment of the device. The primary reason for this is that relatively indirect measures of cognitive function, as can be gleaned from the electroencephalogram (EEG), are harnessed. A more suitable and usable interface would need to measure cognitive function more directly. In order to do this, new measurement modalities, signal acquisition and processing, and translation algorithms need to be addressed. In this paper, we propose a novel approach, using non-invasive near-infrared imaging technology to develop a user-friendly optical BCI. As an alternative to the traditional EEG-based devices, we have used practical non-invasive optical techniques to detect characteristic haemodynamic responses due to motor imagery and consequently created an accessible BCI that is simple to attach and requires little user training.

Ocular counterrolling in response to static and dynamic tilting: implications for human otolith function.

Nineteen subjects underwent rotation about the naso-occipital axis to examine ocular counterrolling (OCR) responses in both dynamic and static conditions. Dynamic rotation consisted of tilt to 90 degrees right and left at constant velocity of 3 degrees /s, with acceleration at 0.2 degrees /s(2). Static rotation (stepwise tilting) consisted of one minute at steps 30 degrees, 60 degrees, 90 degrees, 60 degrees, 30 degrees to each side. OCR amplitudes at each of the above head tilts in dynamic vs. static tilt showed highly significant differences, with dynamic tilt exceeding that of static. Although OCR disconjugacy was greater in static than dynamic in most subjects, that difference was not statistically significant. Possible explanations for the disparity in the responses to dynamic and static tilt in humans lie in vestibular experiments leading to the conclusion that the otolith membrane in cats moves not as a unit, but rather in patches (28). This is supported by work showing the otolith membrane in bullfrogs does not move en bloc (1). In addition, hair cell responses are found to be amplified during motion as compared to the responses during static positioning (20). Functionally, it is suggested that the otolith system may perform better in moving than in static conditions.