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Kunasegaran K, Ismail AMH, Ramasamy S, Gnanou JV, Caszo BA, Chen PL. Understanding mental fatigue and its detection: a comparative analysis of assessments and tools. PeerJ 2023; 11:e15744. [PMID: 37637168 PMCID: PMC10460155 DOI: 10.7717/peerj.15744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 06/21/2023] [Indexed: 08/29/2023] Open
Abstract
Mental fatigue has shown to be one of the root causes of decreased productivity and overall cognitive performance, by decreasing an individual's ability to inhibit responses, process information and concentrate. The effects of mental fatigue have led to occupational errors and motorway accidents. Early detection of mental fatigue can prevent the escalation of symptoms that may lead to chronic fatigue syndrome and other disorders. To date, in clinical settings, the assessment of mental fatigue and stress is done through self-reported questionnaires. The validity of these questionnaires is questionable, as they are highly subjective measurement tools and are not immune to response biases. This review examines the wider presence of mental fatigue in the general population and critically compares its various detection techniques (i.e., self-reporting questionnaires, heart rate variability, salivary cortisol levels, electroencephalogram, and saccadic eye movements). The ability of these detection tools to assess inhibition responses (which are sensitive enough to be manifested in a fatigue state) is specifically evaluated for a reliable marker in identifying mentally fatigued individuals. In laboratory settings, antisaccade tasks have been long used to assess inhibitory control and this technique can potentially serve as the most promising assessment tool to objectively detect mental fatigue. However, more studies need to be conducted in the future to validate and correlate this assessment with other existing measures of mental fatigue detection. This review is intended for, but not limited to, mental health professionals, digital health scientists, vision researchers, and behavioral scientists.
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Affiliation(s)
- Kaveena Kunasegaran
- Department of Psychology, International Medical University, Bukit Jalil, Kuala Lumpur, Malaysia
| | | | - Shamala Ramasamy
- Department of Psychology, International Medical University, Bukit Jalil, Kuala Lumpur, Malaysia
| | - Justin Vijay Gnanou
- Department of Biochemistry, International Medical University, Bukit Jalil, Kuala Lumpur, Malaysia
| | - Brinnell Annette Caszo
- Department of Physiology, International Medial University, Bukit Jalil, Kuala Lumpur, Malaysia
| | - Po Ling Chen
- School of Psychology, University of Nottingham Malaysia, Semenyih, Selangor, Malaysia
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Chen JT, Kuo YC, Hsu TY, Wang CA. Fatigue and Arousal Modulations Revealed by Saccade and Pupil Dynamics. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19159234. [PMID: 35954585 PMCID: PMC9367726 DOI: 10.3390/ijerph19159234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 07/25/2022] [Accepted: 07/27/2022] [Indexed: 11/16/2022]
Abstract
Saccadic eye movements are directed to the objects of interests and enable high-resolution visual images in the exploration of the visual world. There is a trial-to-trial variation in saccade dynamics even in a simple task, possibly attributed to arousal fluctuations. Previous studies have showed that an increase of fatigue level over time, also known as time-on-task, can be revealed by saccade peak velocity. In addition, pupil size, controlled by the autonomic nervous system, has long been used as an arousal index. However, limited research has been done with regards to the relation between pupil size and saccade behavior in the context of trial-to-trial variation. To investigate fatigue and arousal effects on saccadic and pupillary responses, we used bright and emotional stimuli to evoke pupillary responses in tasks requiring reactive and voluntary saccade generation. Decreased voluntary saccade peak velocities, reduced tonic pupil size and phasic pupillary responses were observed as time-on-task increased. Moreover, tonic pupil size affected saccade latency and dynamics, with steeper saccade main sequence slope as tonic pupil size increased. In summary, saccade dynamics and tonic pupil size were sensitive to fatigue and arousal level, together providing valuable information for the understanding of human behavior.
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Affiliation(s)
- Jui-Tai Chen
- Department of Anesthesiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 110, Taiwan;
- Department of Anesthesiology, Shuang Ho Hospital, Taipei Medical University, New Taipei City 235, Taiwan
| | - Ying-Chun Kuo
- Institute of Cognitive Neuroscience, College of Health Science and Technology, National Central University, Taoyuan City 320, Taiwan;
- Cognitive Intelligence and Precision Healthcare Research Center, National Central University, Taoyuan City 320, Taiwan
| | - Tzu-Yu Hsu
- Graduate Institute of Mind, Brain, and Consciousness (GIMBC), Taipei Medical University, Taipei 110, Taiwan;
- Brain and Consciousness Research Center (BCRC), TMU-Shuang Ho Hospital, New Taipei City 235, Taiwan
| | - Chin-An Wang
- Department of Anesthesiology, Shuang Ho Hospital, Taipei Medical University, New Taipei City 235, Taiwan
- Institute of Cognitive Neuroscience, College of Health Science and Technology, National Central University, Taoyuan City 320, Taiwan;
- Cognitive Intelligence and Precision Healthcare Research Center, National Central University, Taoyuan City 320, Taiwan
- Graduate Institute of Mind, Brain, and Consciousness (GIMBC), Taipei Medical University, Taipei 110, Taiwan;
- Brain and Consciousness Research Center (BCRC), TMU-Shuang Ho Hospital, New Taipei City 235, Taiwan
- Correspondence:
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Burlingham CS, Mirbagheri S, Heeger DJ. A unified model of the task-evoked pupil response. SCIENCE ADVANCES 2022; 8:eabi9979. [PMID: 35442730 PMCID: PMC9020670 DOI: 10.1126/sciadv.abi9979] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 03/04/2022] [Indexed: 06/14/2023]
Abstract
The pupil dilates and reconstricts following task events. It is popular to model this task-evoked pupil response as a linear transformation of event-locked impulses, whose amplitudes are used as estimates of arousal. We show that this model is incorrect and propose an alternative model based on the physiological finding that a common neural input drives saccades and pupil size. The estimates of arousal from our model agreed with key predictions: Arousal scaled with task difficulty and behavioral performance but was invariant to small differences in trial duration. Moreover, the model offers a unified explanation for a wide range of phenomena: entrainment of pupil size and saccades to task timing, modulation of pupil response amplitude and noise with task difficulty, reaction time-dependent modulation of pupil response timing and amplitude, a constrictory pupil response time-locked to saccades, and task-dependent distortion of this saccade-locked pupil response.
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Affiliation(s)
| | - Saghar Mirbagheri
- Graduate Program in Neuroscience, University of Washington, Seattle, WA 98195, USA
| | - David J. Heeger
- Department of Psychology, New York University, New York, NY 10003, USA
- Center for Neural Science, New York University, New York, NY 10003, USA
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Wang CA, Nguyen KT, Juan CH. Linking Pupil Size Modulated by Global Luminance and Motor Preparation to Saccade Behavior. Neuroscience 2021; 476:90-101. [PMID: 34571085 DOI: 10.1016/j.neuroscience.2021.09.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 09/03/2021] [Accepted: 09/18/2021] [Indexed: 01/21/2023]
Abstract
Saccades are rapid eye movements that are used to move the high acuity fovea in a serial manner in the exploration of the visual scene. Stimulus contrast is known to modulate saccade latency and metrics possibly via changing visual activity in the superior colliculus (SC), a midbrain structure causally involved in saccade generation. However, the quality of visual signals should also be modulated by the amount of lights projected onto the retina, which is gated by the size of the pupil. Although absolute pupil size should modulate visual signals and in turn affect saccade responses, research examining this relationship is very limited. Besides, pupil size is associated with motor preparation. However, the role of pupil dilation in saccade metrics remains unexplored. Through varying peripheral background luminance level and target visual contrast in the saccade task, we investigated the role of absolute pupil size and baseline-corrected pupil dilation in saccade latency and metrics. Higher target detection accuracy was obtained with lower background luminance level, and larger absolute pupil diameter correlated with smaller saccade amplitude and higher saccade peak velocities. More interestingly, the comparable modulation between pupil dilation and stimulus contrast was obtained, showing larger pupil dilation (or higher contrast stimuli) correlating with faster saccade latencies, larger amplitude, higher peak velocities, and smaller endpoint deviation. Together, our results demonstrated the influence of absolute pupil size induced by global luminance level and baseline-corrected pupil dilation associated with motor preparation on saccade latency and metrics, implicating the role of the SC in this behavior.
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Affiliation(s)
- Chin-An Wang
- Institute of Cognitive Neuroscience, National Central University, Taoyuan City, Taiwan; Cognitive Intelligence and Precision Healthcare Center, National Central University, Taoyuan City, Taiwan.
| | - Kien Trong Nguyen
- Institute of Cognitive Neuroscience, National Central University, Taoyuan City, Taiwan; Faculty of Electronics Engineering, Posts and Telecommunications Institute of Technology, Ho Chi Minh City, Viet Nam
| | - Chi-Hung Juan
- Institute of Cognitive Neuroscience, National Central University, Taoyuan City, Taiwan; Cognitive Intelligence and Precision Healthcare Center, National Central University, Taoyuan City, Taiwan; Department of Psychology, Kaohsiung Medical University, Kaohsiung City, Taiwan
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Wang CA, Munoz DP. Differentiating global luminance, arousal and cognitive signals on pupil size and microsaccades. Eur J Neurosci 2021; 54:7560-7574. [PMID: 34716728 DOI: 10.1111/ejn.15508] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 10/22/2021] [Accepted: 10/23/2021] [Indexed: 10/19/2022]
Abstract
Pupil size reflects a proxy for neural activity associated with global luminance, arousal and cognitive processing. Microsaccades are also modulated by arousal and cognitive processing. Are these effects of arousal and cognitive signals on pupil size and microsaccades coordinated? If so, via what neural mechanisms? We hypothesized that if pupil size and microsaccades are coordinately modulated by these processes, pupil size immediately before microsaccade onset, as an index for ongoing cognitive and arousal processing, should correlate with microsaccade responses during tasks alternating these signals. Here, we examined the relationship between pupil size and microsaccade responses in tasks that included variations in global luminance, arousal and inhibitory control. Higher microsaccade peak velocities correlated with larger pre-microsaccade pupil response related to arousal and inhibitory control signals. In contrast, pupil responses evoked by global luminance signals did not correlate with microsaccade responses. Given the central role of the superior colliculus in microsaccade generation, these results suggest the critical involvement of the superior colliculus to coordinate pupil and microsaccade responses for arousal and inhibitory control modulations, but not for the pupil luminance modulation.
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Affiliation(s)
- Chin-An Wang
- Institute of Cognitive Neuroscience, College of Health Science and Technology, National Central University, Taoyuan City, Taiwan.,Cognitive Intelligence and Precision Healthcare Research Center, National Central University, Taoyuan City, Taiwan
| | - Douglas P Munoz
- Centre for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada
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Hsu TY, Chen JT, Tseng P, Wang CA. Role of the frontal eye field in human microsaccade responses: A TMS study. Biol Psychol 2021; 165:108202. [PMID: 34634433 DOI: 10.1016/j.biopsycho.2021.108202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 09/22/2021] [Accepted: 10/01/2021] [Indexed: 01/02/2023]
Abstract
Microsaccade is a type of fixational eye movements that is modulated by various sensory and cognitive processes, and impact our visual perception. Although studies in monkeys have demonstrated a functional role for the superior colliculus and frontal eye field (FEF) in controlling microsaccades, our understanding of the neural mechanisms underlying the generation of microsaccades is still limited. By applying continuous theta-burst stimulation (cTBS) over the right FEF and the vertex, we investigated the role of the FEF in generating human microsaccade responses evoked by salient stimuli or by changes in background luminance. We observed higher microsaccade rates prior to target appearance, and larger rebound in microsaccade occurrence following salient stimuli, when disruptive cTBS was applied over FEF compared to vertex stimulation. Moreover, the microsaccade direction modulation after changes in background luminance was disrupted with FEF stimulation. Together, our results constitute the first evidence of FEF modulation in human microsaccade responses.
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Affiliation(s)
- Tzu-Yu Hsu
- Graduate Institute of Mind, Brain, and Consciousness (GIMBC), Taipei Medical University, Taipei, Taiwan; Brain and Consciousness Research Center (BCRC), TMU-Shuang Ho Hospital, New Taipei City, Taiwan
| | - Jui-Tai Chen
- Department of Anesthesiology, Shuang Ho Hospital, Taipei Medical University, New Taipei City, Taiwan; Department of Anesthesiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Philip Tseng
- Graduate Institute of Mind, Brain, and Consciousness (GIMBC), Taipei Medical University, Taipei, Taiwan; Brain and Consciousness Research Center (BCRC), TMU-Shuang Ho Hospital, New Taipei City, Taiwan
| | - Chin-An Wang
- Institute of Cognitive Neuroscience, College of Health Science and Technology, National Central University, Taoyuan City, Taiwan; Cognitive Intelligence and Precision Healthcare Research Center, National Central University, Taoyuan City, Taiwan.
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