2008 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2008
Brain computer interfaces (BCIs) can be implemented into assistive technologies to provide &a... more Brain computer interfaces (BCIs) can be implemented into assistive technologies to provide 'hands-free' control for the severely disabled. BCIs utilise voluntary changes in one's brain activity as a control mechanism to control devices in the person's immediate environment. Performance of BCIs could be adversely affected by negative physiological conditions such as fatigue and altered electrophysiology commonly seen in spinal cord injury (SCI). This study examined the effects of mental fatigue from an increase in cognitive demand on the brain activity of those with SCI. Results show a trend of increased alpha (8-13Hz) activity in able-bodied controls after completing a set of cognitive tasks. Conversely, the SCI group showed a decrease in alpha activity due to mental fatigue. Results suggest that the brain activity of SCI persons are altered in its mechanism to adjust to mental fatigue. These altered brain conditions need to be addressed when using BCIs in clinical populations such as SCI. The findings have implications for the improvement of BCI technology.
2011 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2011
This paper presents research that investigated the effects of mental fatigue on brain activity as... more This paper presents research that investigated the effects of mental fatigue on brain activity associated with eyes open and eyes closed conditions. The changes associated with electroencephalography (EEG) alpha wave activity (8-13 Hz) during eye closure has previously been shown to be an effective strategy for switching and activating devices as an environmental control system (ECS) designed for people with severe disability like spinal cord injury (SCI). The results showed that switching times did increase due to fatigue, however, these increases were not large (around 1 second longer to switch) and this difference was not significant. When baselines were readjusted taking into account the change in alpha wave activity due to the fatigue, switching reduced to times typically seen when the person was alert. Error rates were similar between the alert and fatigue sates. Implications of these results for a hands-free ECS are discussed.
2010 Annual International Conference of the IEEE Engineering in Medicine and Biology, 2010
Fatigue can be defined as a state that involves psychological and physical tiredness with a range... more Fatigue can be defined as a state that involves psychological and physical tiredness with a range of symptoms such as tired eyes, yawning and increased blink rate. It has major implications for work place and road safety as well as a negative symptom of many acute and chronic illnesses. As such there has been considerable research dedicated to systems or algorithms that can be used to detect and monitor the onset of fatigue. This paper examines using electroencephalography (EEG) signals to classify fatigue and alert states as a function of subjective self-report, driving performance and physiological symptoms. The results show that EEG classification network for fatigue improved from 75% to 80% when these factors are applied, especially when the data is grouped by subjective self-report of fatigue with classification accuracy improving to 84.5%.
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2009
Fatigue is a negative symptom of many illnesses and also has major implications for road safety. ... more Fatigue is a negative symptom of many illnesses and also has major implications for road safety. This paper presents results using a method called microstate segmentation (MSS). It was used to distinguish changes from an alert to a fatigue state. The results show a significant increase in MSS instantaneous amplitude during the fatigue state. Plotting the linear gradient of the nonlinear part of the phase data from the MSS also showed a significant difference (P<0.01) in the gradients of the alert state compared to the fatigue state. The results suggest that MSS can be used in analyzing spontaneous electroencephalography (EEG) signals to detect changes in physiological states. The results have implications for countermeasures used in detecting fatigue.
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2014
This paper presents research that investigated the effects of mental fatigue on brain activity us... more This paper presents research that investigated the effects of mental fatigue on brain activity using electroencephalogram (EEG) signals. Since EEG signals are considered to be non-stationary, time-frequency analysis has frequently been used for analysis. The S-transform is a time-frequency analysis method and is used in this paper to analyze EEG signals during alert and fatigue states during a driving simulator task. Repeated-measure MANOVA results show significant differences between alert and fatigue states within the alpha (8-13Hz) frequency band. The two sites demonstrating the greatest increases in alpha activity during fatigue were the Cz and P4 sites. The results show that S-transform analysis can be used to distinguish between alert and fatigue states in the EEG and also supports the use of the S-transform for EEG analysis.
The Australian Journal of Rehabilitation Counselling, 2012
ABSTRACT This study investigated fatigue and anger in people with SCI. Participants were 27 adult... more ABSTRACT This study investigated fatigue and anger in people with SCI. Participants were 27 adults with SCI living in the community (males = 26, females = 1; mean age = 50 years, SD = 9.47 years) and a comparison group of 27 other adults without SCI. Data about their experience of fatigue and anger were collected using the Chalder Fatigue Scale and the Profile of Mood States. Kruskal-Wallis ANOVA by ranks and chi-square analyses were used to determine whether the SCI participants had elevated levels of fatigue and anger than the typical or noninjured community group. Persons with SCI reported significantly elevated fatigue and elevated levels of anger than typical others. These findings are discussed with reference to adjustment following SCI, and interpreted in light of the Stress Appraisal and Coping Model (SAC) of adjustment following SCI.
Fatigue is a common symptom in people with neurological injury such as spinal cord injury (SCI), ... more Fatigue is a common symptom in people with neurological injury such as spinal cord injury (SCI), though its nature and occurrence in people with SCI are not well understood. The objective of this research was to investigate fatigue and its relationship to factors such as mood states and self efficacy in adult people with SCI compared to able-bodied controls. Participants included 41 adults with SCI living in the community and 41 able-bodied controls matched for age and sex ratios and education. All participants first completed a comprehensive psychological assessment and were then asked to take part in a 2-3 hour session composed of a regimen of cognitive tasks that required constant concentration and attention. Participants were assessed after completing this task. The SCI group was found to have significantly elevated levels of fatigue, as well as elevated depressive mood, anxiety and poor self-efficacy. The SCI group was also found to suffer excessive levels of tiredness as a consequence of the 2-3 hour task. Factors such as depressive mood and poor self-efficacy were shown to increase the risk of excessive tiredness. People with a neurological injury such as SCI have a high risk of having fatigue and are susceptible to experiencing excessive tiredness when performing extended tasks, and the presence of elevated depressive mood or poor expectations towards self management will increase this susceptibility. Implications for managing fatigue and improving social access in SCI populations are discussed.
Fatigue is a prevalent problem in the workplace and a common symptom of many diseases. However, i... more Fatigue is a prevalent problem in the workplace and a common symptom of many diseases. However, its relationship with the autonomic nervous system, specifically with sympathetic arousal, needs clarification. The objective of this study was to determine the association between fatigue and heart rate variability (HRV). HRV is regarded as an indicator of the autonomic regulation activity of heart rate,
This investigation examined the impact of spinal cord injury (SCI) on task-relevant processing us... more This investigation examined the impact of spinal cord injury (SCI) on task-relevant processing using event-related potentials. Thirty-seven participants with chronic SCI and 37 healthy able-bodied controls were tested in this study. An auditory two-tone button press oddball discrimination paradigm was used to evoke the N100, P200, N200, and P300 components of the event-related potential. During the early sensory/perceptual stages of target stimulus processing, the SCI group showed an earlier right posterior P200 latency relative to the controls. In the later more cognitive stages, a pattern of diminished left and right posterior P300 amplitude was also evident. This was further coupled with increased false-positive errors and greater variability of response time in the SCI group. The results of this study indicate that people with SCI show disturbances in inhibitory function and alterations in both early perceptual encoding processes and in later executive functioning that engages contextual/memory-updating operations.
Driver fatigue is a major risk for road accidents that can often result in injury and death. Howe... more 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.
Driver fatigue is associated with risks of road accidents that result in injury and death. Resear... more 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.
2008 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2008
Brain computer interfaces (BCIs) can be implemented into assistive technologies to provide &a... more Brain computer interfaces (BCIs) can be implemented into assistive technologies to provide &amp;amp;#39;hands-free&amp;amp;#39; control for the severely disabled. BCIs utilise voluntary changes in one&amp;amp;#39;s brain activity as a control mechanism to control devices in the person&amp;amp;#39;s immediate environment. Performance of BCIs could be adversely affected by negative physiological conditions such as fatigue and altered electrophysiology commonly seen in spinal cord injury (SCI). This study examined the effects of mental fatigue from an increase in cognitive demand on the brain activity of those with SCI. Results show a trend of increased alpha (8-13Hz) activity in able-bodied controls after completing a set of cognitive tasks. Conversely, the SCI group showed a decrease in alpha activity due to mental fatigue. Results suggest that the brain activity of SCI persons are altered in its mechanism to adjust to mental fatigue. These altered brain conditions need to be addressed when using BCIs in clinical populations such as SCI. The findings have implications for the improvement of BCI technology.
2011 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2011
This paper presents research that investigated the effects of mental fatigue on brain activity as... more This paper presents research that investigated the effects of mental fatigue on brain activity associated with eyes open and eyes closed conditions. The changes associated with electroencephalography (EEG) alpha wave activity (8-13 Hz) during eye closure has previously been shown to be an effective strategy for switching and activating devices as an environmental control system (ECS) designed for people with severe disability like spinal cord injury (SCI). The results showed that switching times did increase due to fatigue, however, these increases were not large (around 1 second longer to switch) and this difference was not significant. When baselines were readjusted taking into account the change in alpha wave activity due to the fatigue, switching reduced to times typically seen when the person was alert. Error rates were similar between the alert and fatigue sates. Implications of these results for a hands-free ECS are discussed.
2010 Annual International Conference of the IEEE Engineering in Medicine and Biology, 2010
Fatigue can be defined as a state that involves psychological and physical tiredness with a range... more Fatigue can be defined as a state that involves psychological and physical tiredness with a range of symptoms such as tired eyes, yawning and increased blink rate. It has major implications for work place and road safety as well as a negative symptom of many acute and chronic illnesses. As such there has been considerable research dedicated to systems or algorithms that can be used to detect and monitor the onset of fatigue. This paper examines using electroencephalography (EEG) signals to classify fatigue and alert states as a function of subjective self-report, driving performance and physiological symptoms. The results show that EEG classification network for fatigue improved from 75% to 80% when these factors are applied, especially when the data is grouped by subjective self-report of fatigue with classification accuracy improving to 84.5%.
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2009
Fatigue is a negative symptom of many illnesses and also has major implications for road safety. ... more Fatigue is a negative symptom of many illnesses and also has major implications for road safety. This paper presents results using a method called microstate segmentation (MSS). It was used to distinguish changes from an alert to a fatigue state. The results show a significant increase in MSS instantaneous amplitude during the fatigue state. Plotting the linear gradient of the nonlinear part of the phase data from the MSS also showed a significant difference (P<0.01) in the gradients of the alert state compared to the fatigue state. The results suggest that MSS can be used in analyzing spontaneous electroencephalography (EEG) signals to detect changes in physiological states. The results have implications for countermeasures used in detecting fatigue.
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2014
This paper presents research that investigated the effects of mental fatigue on brain activity us... more This paper presents research that investigated the effects of mental fatigue on brain activity using electroencephalogram (EEG) signals. Since EEG signals are considered to be non-stationary, time-frequency analysis has frequently been used for analysis. The S-transform is a time-frequency analysis method and is used in this paper to analyze EEG signals during alert and fatigue states during a driving simulator task. Repeated-measure MANOVA results show significant differences between alert and fatigue states within the alpha (8-13Hz) frequency band. The two sites demonstrating the greatest increases in alpha activity during fatigue were the Cz and P4 sites. The results show that S-transform analysis can be used to distinguish between alert and fatigue states in the EEG and also supports the use of the S-transform for EEG analysis.
The Australian Journal of Rehabilitation Counselling, 2012
ABSTRACT This study investigated fatigue and anger in people with SCI. Participants were 27 adult... more ABSTRACT This study investigated fatigue and anger in people with SCI. Participants were 27 adults with SCI living in the community (males = 26, females = 1; mean age = 50 years, SD = 9.47 years) and a comparison group of 27 other adults without SCI. Data about their experience of fatigue and anger were collected using the Chalder Fatigue Scale and the Profile of Mood States. Kruskal-Wallis ANOVA by ranks and chi-square analyses were used to determine whether the SCI participants had elevated levels of fatigue and anger than the typical or noninjured community group. Persons with SCI reported significantly elevated fatigue and elevated levels of anger than typical others. These findings are discussed with reference to adjustment following SCI, and interpreted in light of the Stress Appraisal and Coping Model (SAC) of adjustment following SCI.
Fatigue is a common symptom in people with neurological injury such as spinal cord injury (SCI), ... more Fatigue is a common symptom in people with neurological injury such as spinal cord injury (SCI), though its nature and occurrence in people with SCI are not well understood. The objective of this research was to investigate fatigue and its relationship to factors such as mood states and self efficacy in adult people with SCI compared to able-bodied controls. Participants included 41 adults with SCI living in the community and 41 able-bodied controls matched for age and sex ratios and education. All participants first completed a comprehensive psychological assessment and were then asked to take part in a 2-3 hour session composed of a regimen of cognitive tasks that required constant concentration and attention. Participants were assessed after completing this task. The SCI group was found to have significantly elevated levels of fatigue, as well as elevated depressive mood, anxiety and poor self-efficacy. The SCI group was also found to suffer excessive levels of tiredness as a consequence of the 2-3 hour task. Factors such as depressive mood and poor self-efficacy were shown to increase the risk of excessive tiredness. People with a neurological injury such as SCI have a high risk of having fatigue and are susceptible to experiencing excessive tiredness when performing extended tasks, and the presence of elevated depressive mood or poor expectations towards self management will increase this susceptibility. Implications for managing fatigue and improving social access in SCI populations are discussed.
Fatigue is a prevalent problem in the workplace and a common symptom of many diseases. However, i... more Fatigue is a prevalent problem in the workplace and a common symptom of many diseases. However, its relationship with the autonomic nervous system, specifically with sympathetic arousal, needs clarification. The objective of this study was to determine the association between fatigue and heart rate variability (HRV). HRV is regarded as an indicator of the autonomic regulation activity of heart rate,
This investigation examined the impact of spinal cord injury (SCI) on task-relevant processing us... more This investigation examined the impact of spinal cord injury (SCI) on task-relevant processing using event-related potentials. Thirty-seven participants with chronic SCI and 37 healthy able-bodied controls were tested in this study. An auditory two-tone button press oddball discrimination paradigm was used to evoke the N100, P200, N200, and P300 components of the event-related potential. During the early sensory/perceptual stages of target stimulus processing, the SCI group showed an earlier right posterior P200 latency relative to the controls. In the later more cognitive stages, a pattern of diminished left and right posterior P300 amplitude was also evident. This was further coupled with increased false-positive errors and greater variability of response time in the SCI group. The results of this study indicate that people with SCI show disturbances in inhibitory function and alterations in both early perceptual encoding processes and in later executive functioning that engages contextual/memory-updating operations.
Driver fatigue is a major risk for road accidents that can often result in injury and death. Howe... more 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.
Driver fatigue is associated with risks of road accidents that result in injury and death. Resear... more 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.
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Papers by Nirupama Wijesuriya