Biomedical subjects

Ashley Craig

Publications and source records attributed to Ashley Craig.

14 recordsLinked to original sources

PubMed2006

The psychophysiological determinants of fatigue.

Driver fatigue is a major risk for road accidents that can often result in injury and death. However, considerable debate still exists concerning factors associated with driver fatigue. Because of the complex nature of fatigue, this paper reports a study that investigated both physiological and psychological determinants of fatigue. Three fatigue outcome measures were used, including a physiological, psychological and a combined physiological and psychological measure. Fifty participants performed a driving simulator task till they showed symptoms of fatigue and were assessed before and after the task. Significant factors associated with physiological fatigue included higher levels of baseline delta activity and an extraverted personality. Factors related to the psychological fatigue outcome measure included sleepiness, low healthy lifestyle status, an extraverted personality and tension-prone personality, and negative mood states. The combined fatigue outcome measure was associated with factors such as a tension-prone and extraverted personality, low systolic blood pressure, and negative mood states. The findings emphasize the importance of assessing fatigue using a range of outcome measures in order to achieve a thorough understanding of what factors contribute to fatigue and highlight the need to develop fatigue countermeasures that employ a broad range of measures.

Adult↗

PubMed2005

A controlled investigation into the psychological determinants of fatigue.

Driver fatigue is associated with risks of road accidents that result in injury and death. Research has been limited by several issues such as confusion over definitions, how best to measure fatigue, and the contribution of psychological factors to fatigue. This study addressed these limitations by investigating the relationship between psychological factors and fatigue. Participants were assessed and were required to perform a monotonous task till they tired. Results found few psychological factors to be related to physiological and performance decrement fatigue outcome measures. However, psychological factors were found to correlate consistently with self-reported fatigue. The results suggest that fatigue is associated with a predisposition to be anxious, depressive, less self-assured, more conscientious (rule bound), less socially bold, less adaptable and low vigour. The results indicate that future research should employ a range of fatigue outcome measures in order to best understand what factors contribute to fatigue.

Adolescent↗

PubMed2005

Improving correct switching rates in a 'hands-free' environmental control system.

One potential negative impact on the quality of life of a spinal cord injured person is the loss of the ability to control devices in their immediate environment. Consequently, research and development has been conducted on technology designed to restore some measure of independence by providing means of control over these devices. A previous assistive device using changes in brain signals from eye closure as its switching system was created. Brain signals were processed using spectral analysis and although this was a successful technique, there were limitations that resulted in higher than desired switching errors. This paper presents results of an alternative method for processing brain signals as the basis for switching, called fractal dimension. In comparison to the spectral technique, the fractal dimension technique was successful in reducing the number of false positive and false negative errors. Additionally, it eliminated the need for a baseline setup for this system. This suggests that fractal dimension is a potentially viable method for analysing brain signals for use in assistive control systems.

Adult↗

PubMed2005

Personality traits and its association with resting regional brain activity.

The association between personality and resting brain activity was investigated. Personality was assessed using the NEO-Five-factor Inventory (NEO-FFI) and resting brain activity was indexed by eyes closed EEG spectral magnitude from four frequency bands over the entire cortex. Results suggest that there are differences between males and females in the NEO-FFI personality traits. The NEO FFI traits were associated with lower frequency brain activity in both males and females. Mild significant and consistent associations were found between delta and theta activity across all cortical regions with Extraversion and Conscientiousness. There were few associations between personality traits and alpha and beta activity, this was shown in males only. Fewer associations between personality and faster frequency bands such as alpha may be due to the methodological problem of using fixed alpha bands. Multiple regression analyses showed that individual alpha frequencies had a greater contribution to personality traits than fixed band alpha waves.

Adolescent↗

PubMed2005

Reproducibility of the spectral components of the electroencephalogram during driver fatigue.

OBJECTIVE: To date, no study has tested the reproducibility of EEG changes that occur during driver fatigue. For the EEG changes to be useful in the development of a fatigue countermeasure device the EEG response during each onset period of fatigue in individuals needs to be reproducible. It should be noted that fatigue during driving is not a continuous process but consists of successive episodes of 'microsleeps' where the subject may go in and out of a fatigue state. The aim of the present study was to investigate the reproducibility of fatigue during driving in both professional and non-professional drivers. METHODS: Thirty five non-professional drivers and twenty professional drivers were tested during two separate sessions of a driver simulator task. EEG, EOG and behavioural measurements of fatigue were obtained during the driving task. RESULTS: The results showed high reproducibility for the delta and theta bands (r>0.95) in both groups of drivers. CONCLUSIONS: The results are discussed in light of implications for future studies and for the development of an EEG based fatigue countermeasure device.

Adult↗

PubMed2005

The efficacy and benefits of environmental control systems for the severely disabled.

BACKGROUND: People living with a severe disability suffer substantial personal and social consequences that reduce quality of life (QOL). One potential negative impact on the QOL of a disabled person is the loss of the ability to control devices in their immediate environment (such as the television, computer, telephones, lights, doors, etc.). Consequently, research and development has been conducted on technology designed to restore independence by providing some means of control over these devices. Technology that allows a severely disabled person to gain this type of control has been called an environmental control system (ECS). The aim of this review was to evaluate critically the status and efficacy of ECS technology for the severely disabled. MATERIALS/METHODS: To achieve this, a comprehensive database search was conducted for relevant material on technical and clinical aspects of ECS control. RESULTS: The review demonstrated that there is an abundance of work conducted on ECS technology, resulting in a number of creative control systems that are designed to be used by the severely disabled. These include switching systems that utilize voice, muscle, brain activity, head motion, eye blink, breath, chin, and so on. However, the review also established that rarely has the efficacy of these systems been scientifically established. CONCLUSIONS: Severely disabled persons need access to ECS technology that has been shown to be efficacious. While the severely disabled gain benefits from using ECS technology, challenges still exist before ECS technology for the severely disabled can provide highly reliable and user-friendly device control.

Communication Devices for People with Disabilities↗

PubMed2004

Time course and regional distribution of cortical changes during acute alcohol ingestion.

Behavioral effects of alcohol are known to be greater when the blood alcohol is rising, known as the Mellanby effect; however, research investigating the cortical changes during this period is scarce. The objective of this study was to investigate the effects of consumption of alcohol on cortical activity measured by the electroencephalogram (EEG) during the absorption or rising phase of alcohol. EEG signals were recorded using the entire 10/20 montage system. The experimental design consisted of a repeated measures randomized crossover design in which subjects acted as their own control. This involved recording two EEG baseline measures, each of which was followed by a placebo or alcohol condition, delivered over two days for ten subjects. All subjects had a 50% chance of receiving the alcohol first. All subjects were shown to have mean peak blood alcohol concentration (BAC) levels of around.03%. No significant differences were found between the two baselines. Significant increases in EEG magnitude occurred in the theta (4-7.75 Hz), alpha 1 (8-9.75 Hz), and beta 1 (13.25-19.75 Hz) spectrum in the frontal EEG regions, and alpha 1 (8-9.75 Hz,) in the central and posterior regions. No significant changes were found in the theta (4-7.75 Hz) or beta (13.5-30 Hz) spectrums in the central and posterior regions. There were also no significant results for alpha 2 (10-13 Hz,) in any of the regions. These results suggest that rapid cortical changes occur within the first 35 min after alcohol consumption.

Adult↗

PubMed2003

Development of an algorithm for an EEG-based driver fatigue countermeasure.

PROBLEM: Fatigue affects a driver's ability to proceed safely. Driver-related fatigue and/or sleepiness are a significant cause of traffic accidents, which makes this an area of great socioeconomic concern. Monitoring physiological signals while driving provides the possibility of detecting and warning of fatigue. The aim of this paper is to describe an EEG-based fatigue countermeasure algorithm and to report its reliability. METHOD: Changes in all major EEG bands during fatigue were used to develop the algorithm for detecting different levels of fatigue. RESULTS: The software was shown to be capable of detecting fatigue accurately in 10 subjects tested. The percentage of time the subjects were detected to be in a fatigue state was significantly different than the alert phase (P<.01). DISCUSSION: This is the first countermeasure software described that has shown to detect fatigue based on EEG changes in all frequency bands. Field research is required to evaluate the fatigue software in order to produce a robust and reliable fatigue countermeasure system. IMPACT ON INDUSTRY: The development of the fatigue countermeasure algorithm forms the basis of a future fatigue countermeasure device. Implementation of electronic devices for fatigue detection is crucial for reducing fatigue-related road accidents and their associated costs.

Accidents, Traffic↗

PubMed2003

Allosteric effects mediate CHK2 phosphorylation of the p53 transactivation domain.

The tumour suppressor p53 is a tetrameric protein that is phosphorylated in its BOX-I transactivation domain by checkpoint kinase 2 (CHK2) in response to DNA damage. CHK2 cannot phosphorylate small peptide fragments of p53 containing the BOX-I motif, indicating that undefined determinants in the p53 tetramer mediate CHK2 recognition. Two peptides derived from the DNA-binding domain of p53 bind to CHK2 and stimulate phosphorylation of full-length p53 at Thr 18 and Ser 20, thus identifying CHK2-docking sites. CHK2 can be fully activated in trans by the two p53 DNA-binding-domain peptides, and can phosphorylate BOX-I transactivation-domain fragments of p53 at Thr 18 and Ser 20. Although CHK2 has a basal Ser 20 kinase activity that is predominantly activated towards Thr 18, CHK1 has constitutive Thr 18 kinase activity that is predominantly activated in trans towards Ser 20. Cell division cycle 25C (CDC25C) phosphorylation by CHK2 is unaffected by the p53 DNA-binding-domain peptides. The CHK2-docking site in the BOX-V motif is the smallest of the two CHK2 binding sites, and mutating certain amino acids in the BOX-V peptide prevents CHK2 activation. A database search identified a p53 BOX-I-homology motif in p21(WAF1) and although CHK2 is inactive towards this protein, the p53 DNA-binding-domain peptides induce phosphorylation of p21(WAF1) at Ser 146. This provides evidence that CHK2 can be activated allosterically towards some substrates by a novel docking interaction, and identify a potential regulatory switch that may channel CHK2 into distinct signalling pathways in vivo.

Allosteric Regulation↗

PubMed2003

Anxiety levels in people who stutter: a randomized population study.

The question of whether people who stutter are generally more anxious than people who do not stutter has not yet been resolved. One major methodological barrier to determining whether differences exist has been the type of stuttering sample used. Studies investigating anxiety levels of those who stutter have mostly assessed people referred to stuttering therapy clinics, which is arguably a biased sample. To date, no studies have been published that have measured the anxiety levels of people who stutter in the community using random selection procedures. Such a sample is more likely to be representative of the population of people who stutter. The present study involved a random selection and telephone interview of people in 4,689 households. The telephone respondent was given a description of stuttering and asked if any person living in their household stuttered. If yes, a number of corroborative questions were asked, and permission was requested to tape the speech of the person believed to stutter over the telephone. A definite case of stuttering was based on (a) a positive detection of stuttering from the tape and (b) at least one of the corroborative questions supporting the diagnosis. A total of 87 people were identified as definite cases of stuttering across all ages, and 63 participants who were 15 years or older completed a trait anxiety questionnaire over the telephone. Mean trait anxiety levels were significantly higher than levels generally found in society, though differences were not large. Implications of these results are discussed.

Adolescent↗

PubMed2003

Stereotypes towards stuttering for those who have never had direct contact with people who stutter: a randomized and stratified study.

Research suggests that many people hold pervasive negative stereotypes towards persons who stutter and that to date, success in changing these attitudes has been limited. However, few studies have selected people who had not had direct contact with a person who stutters or employed a true randomized and stratified selection of people from the community to assess attitudes towards stuttering. To assess stereotypes, a randomized and stratified investigation was conducted by telephone interview to assess the type of stereotypes 502 people from households in the state of New South Wales. Australia have about stuttering. Consenting persons were given a brief introduction to the research and a description of stuttering. Then they were asked if they or any person living in their household stuttered or whether they knew or had ever met any one who stuttered. If answers were no, they were asked to participate. If they answered yes to either question they were thanked and not asked to participate. Analysis showed that a large number believe persons who stutter are shy, self-conscious, anxious people who lack confidence. In contrast, many also believe they would not be embarrassed talking to someone who stutters, that they have average or above average intelligence, and are capable of holding responsible work-related positions. While this research yields a mixture of negative and positive community stereotypes, a significant portion of society continue to show little knowledge of the causes of the disorder.

Adult↗

PubMed2002

Driver fatigue: electroencephalography and psychological assessment.

Fatigue has major implications for transportation system safety; therefore, investigating the psychophysiological links to fatigue could enhance our understanding and management of fatigue in the transport industry. This study examined the psychophysiological changes that occurred during a driver simulator task in 35 randomly selected subjects. Results showed that significant electroencephalographic changes occur during fatigue. Delta and theta activity were found to increase significantly during fatigue. Heart rate was significantly lower after the driving task. Blink rate also changed during the fatigue task. Increased trait anxiety, tension-anxiety, fatigue-inertia and reduced vigor-activity were shown to be associated with neurophysiological indicators of fatigue such as increased delta and theta activity. The results are discussed in light of directions for future studies and for the development of a fatigue countermeasure device.

Adult↗

PubMed2002

Epidemiology of stuttering in the community across the entire life span.

A randomized and stratified investigation was conducted into the epidemiology of stuttering in the community across the entire life span. Persons from households in the state of New South Wales, Australia, were asked to participate in a telephone interview. Consenting persons were given a brief introduction to the research, and details were requested concerning the number and age of the persons living in the household at the time of the interview. Interviewees were then given a description of stuttering. Based on this description, they were asked if any person living in their household stuttered (prevalence). If they answered "yes," a number of corroborative questions were asked, and permission was requested to tape over the telephone the speech of the person who stutters. Confirmation of stuttering was based on (a) a positive detection of stuttering from the tape and (b) an affirmative answer to at least one of the corroborative questions supporting the diagnosis. Results showed that the prevalence of stuttering over the whole population was 0.72%, with higher prevalence rates in younger children (1.4-1.44) and lowest rates in adolescence (0.53). Male-to-female ratios ranged from 2.3:1 in younger children to 4:1 in adolescence, with a ratio of 2.3:1 across all ages. The household member being interviewed was also asked whether anyone in the household had ever stuttered. If the answer was "yes," the same corroborative questions were asked. These data, along with the prevalence data, provided an estimate of the incidence or risk of stuttering, which was found to range from 2.1% in adults (21-50 years) to 2.8% in younger children (2-5 years) and 3.4% in older children (6-10 years). Implications of these results are discussed.

Adolescent↗

PubMed2002

The effectiveness of a hands-free environmental control system for the profoundly disabled.

OBJECTIVE: To investigate the effectiveness of a hands-free environmental control system (ECS) that allows profoundly disabled persons to activate and control electric devices in their home by using consciously controlled changes in their brain signals. DESIGN: A cohort study with a field trial testing of the ECS on 3 occasions. SETTING: Participants' homes. PARTICIPANTS: Ten profoundly disabled persons (mean age, 42.9 y), all of whom had very limited movement from the neck downward. Six had spinal cord injury with lesions ranging from C2 to C5-6. The other 4 had profound disability (1 each from polio, spinal muscular atrophy, multiple sclerosis, cerebral palsy). INTERVENTIONS: Participants performed tasks on each of 3 test occasions. The tasks consisted of turning a television on at the beginning of the trial, changing channels (up, down), changing volume, and turning it off at the conclusion of each trial. MAIN OUTCOME MEASURES: Time participants took to select the correct option and number of errors made in selecting the correct option. Measures were taken for each trial, so that any improvement in switching could be detected. RESULTS: All participants effectively used the ECS to operate their television sets. Selecting a correct option took about 30 seconds (with the majority of this time attributed to machine cycling time), with an error rate of 1.8 per 5 options selected. The time taken to operate the ECS reduced slightly over the 3 trials and selection errors reduced by around 50% (to less than 1 error per 5 options). CONCLUSIONS: With minimal training, profoundly disabled persons were able to use an ECS that uses changes in brain wave signals. This result demonstrates the efficacy of an additional and novel ECS in an area in which few switches are available.

Adult↗