Arousal facilitates involuntary eye movements

DiGirolamo, Gregory J.; Patel, Neha; Blaukopf, Clare L.

doi:10.1007/s00221-016-4599-3

Cited by 20 publications

(20 citation statements)

References 41 publications

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“…Specifically, we compared the rate of eyeblinks as a measure of drowsiness. 35 , 36 Our results ( Fig. 6F ) showed that the difference is not significant enough to be of concern.…”

Section: Discussionmentioning

confidence: 64%

“…It is plausible that DRFE patients are in a more drowsy state at the time of EEG recording because of medication effects, previous seizures, and sleep deprivation. To analyse this effect, we utilized the rate of eye blinks as a surrogate for drowsiness 35 , 36 and compared the number of eye blinks per minute in the eyes open EEG segments of healthy and DRFE individuals.…”

Section: Methodsmentioning

confidence: 99%

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Characterizing the electrophysiological abnormalities in visually reviewed normal EEGs of drug-resistant focal epilepsy patients

Varatharajah

Berry

Joseph

et al. 2021

Brain Communications

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Routine scalp EEG is essential in the clinical diagnosis and management of epilepsy. However, a normal scalp EEG (based on expert visual review) recorded from a patient with epilepsy can cause delays in diagnosis and clinical care delivery. Here we investigated whether normal EEGs might contain subtle electrophysiological clues of epilepsy. Specifically, we investigated a) whether there are indicators of abnormal brain electrophysiology in normal EEGs of epilepsy patients and b) whether such abnormalities are modulated by the side of the brain generating seizures in focal epilepsy. We analyzed awake scalp EEG recordings of age-matched groups of 144 healthy individuals and 48 individuals with drug-resistant focal epilepsy (DRFE) who had normal scalp EEGs. After preprocessing, using a bipolar montage of eight channels, we extracted the fraction of spectral power in the alpha band (8-13 Hz) relative to a wide band of 0.5-40 Hz within 10-second windows. We analyzed the extracted features for a) the extent to which people with DRFE differed from healthy subjects and b) whether differences within the DRFE patients were related to the hemisphere generating seizures. We then used those differences to classify whether an EEG is likely to have been recorded from a person with DRFE, and if so, the epileptogenic hemisphere. Furthermore, we tested the significance of these differences while controlling for confounders such as acquisition system, age, and medications. We found that the fraction of alpha power is generally reduced a) in DRFE compared to healthy controls, and b) in right-handed DRFE subjects with left hemispheric seizures compared to those with right hemispheric seizures, and that the differences are most prominent in the frontal and temporal regions. The fraction of alpha power yielded area under curve values of 0.83 in distinguishing DRFE from healthy and 0.77 in identifying the epileptic hemisphere in DRFE patients. Furthermore, our results suggest that the differences in alpha power are greater when compared with differences attributable to acquisition system differences, age, and medications. Our findings support that EEG-based measures of normal brain function, such as the normalized spectral power of alpha activity, may help identify patients with epilepsy even when an EEG does not contain any epileptiform activity, recorded seizures, or other abnormalities. Although alpha abnormalities are unlikely to be disease-specific, we propose that such abnormalities may provide a higher pre-test probability for epilepsy when an individual being screened for epilepsy has a normal EEG on visual assessment.

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“…Specifically, we compared the rate of eyeblinks as a measure of drowsiness. 35 , 36 Our results ( Fig. 6F ) showed that the difference is not significant enough to be of concern.…”

Section: Discussionmentioning

confidence: 64%

Section: Methodsmentioning

confidence: 99%

Characterizing the electrophysiological abnormalities in visually reviewed normal EEGs of drug-resistant focal epilepsy patients

Varatharajah

Berry

Joseph

et al. 2021

Brain Communications

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“…A large body of work has shown that arousal is associated with changes in the action of the eyes, be it when they are relatively stable or when they move. For example, increases in arousal are typically accompanied by increases in pupil size and saccade velocity, and concomitant decreases in microsaccade rate and reaction time [8][9][10][11][12][13][30][31][32][33][38][39][40][41]. Given that arousal is a domain-general phenomenon, one might expect a similar pattern to emerge on different behavioral tasks.…”

Section: Correlations Between the Eye Metrics Over Timementioning

confidence: 99%

The eyes reflect an internal cognitive state hidden in the population activity of cortical neurons

Johnston

Snyder

Khanna

et al. 2020

Preprint

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SummaryDecades of research have shown that global brain states such as arousal can be indexed by measuring the properties of the eyes. Neural signals from individual neurons, populations of neurons, and field potentials measured throughout much of the brain have been associated with the size of the pupil, small fixational eye movements, and vigor in saccadic eye movements. However, precisely because the eyes have been associated with modulation of neural activity across the brain, and many different kinds of measurements of the eyes have been made across studies, it has been difficult to clearly isolate how internal states affect the behavior of the eyes, and vice versa. Recent work in our laboratory identified a latent dimension of neural activity in macaque visual cortex on the timescale of minutes to tens of minutes. This ‘slow drift’ was associated with perceptual performance on an orientation-change detection task, as well as neural activity in visual and prefrontal cortex (PFC), suggesting it might reflect a shift in a global brain state. This motivated us to ask if the neural signature of this internal state is correlated with the action of the eyes in different behavioral tasks. We recorded from visual cortex (V4) while monkeys performed a change detection task, and the prefrontal cortex, while they performed a memory-guided saccade task. On both tasks, slow drift was associated with a pattern that is indicative of changes in arousal level over time. When pupil size was large, and the subjects were in a heighted state of arousal, microsaccade rate and reaction time decreased while saccade velocity increased. These results show that the action of the eyes is associated with a dominant mode of neural activity that is pervasive and task-independent, and can be accessed in the population activity of neurons across the cortex.

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“…Instead, we speculate that our results may reflect wake and circadian changes in arousal. For instance, heightened arousal is known to facilitate the reflexive response, leading to an increase in antisaccade errors 31 . The biological clock temporally regulates arousal 32 via the locus coeruleus norepinephrine system, whose signals are proposed to enable transitions between sleep (low arousal), focused alert (moderate arousal), and exploratory (high arousal) states 33 .…”

Section: Discussionmentioning

confidence: 99%

Differential Impact of Sleep Deprivation and Circadian Timing on Reflexive Versus Inhibitory Control of Attention

Collet

Ftouni

Clough

et al. 2020

Sci Rep

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In a visually stimulating environment with competing stimuli, we continually choose where to allocate attention, and what to ignore. Wake and circadian-dependent modulation of attentional control and resolution of conflict is poorly understood. Twenty-two participants (17males; 25.6 ± 5.6 years) completed ocular motor tasks throughout 40 hours of sleep deprivation under constant routine conditions. A prosaccade task required a reflexive saccade toward a stimulus (no conflict), while an antisaccade task required inhibiting a reflexive saccade to the peripheral stimulus, and looking in the mirror opposite instead (conflict resolution). Antisaccade inhibitory errors showed circadian modulation, being highest in the morning, progressively decreasing until melatonin onset, before returning to the prior morning's peak throughout the biological night. This diurnal rhythm was blunted by sleep loss (>24 hours), with inhibitory control remaining impaired across the second biological day. For prosaccade, responses slowed down during the biological night. Taken together, we provide evidence for a circadian modulation of attentional bias: the morning being biased toward reflexive responding, and the evening toward higher inhibitory control. Our data show that sleep loss and circadian timing differentially impact attention, depending on whether a response conflict is present (antisaccade) or absent (prosaccade). The capacity to remain vigilant to the environment, and able to quickly respond to relevant stimuli, is critically important to many modern-day activities, such as driving and surveillance of safety-critical systems. The need for a rapid response to relevant stimuli however, must be balanced against the need to inhibit automatic responses toward distractors (e.g., avoid looking at a flashing billboard while driving). Continual resolution of this conflict, between whether to respond to an external stimulus or to inhibit the response toward it, forms the executive component of attention allocation 1 and is critical to many higher order cognitive functions 2. The wake-and circadian-modulation of sustained attention has been well characterised 3-5 using the Psychomotor Vigilance Task. In healthy, well-rested individuals performance on this task remains stable across the waking day, followed by a sharp reduction in sustained attention when wakefulness extends beyond 16 hours awake 5,6. This is due to a combination of both wake (e.g., extended time awake without sleep) and circadian factors (e.g., the drive for sleep during the biological night). While this provides information regarding the capacity to continually monitor and respond to a single stimulus, less is known about wake-and circadian-dependent changes in the resolution of conflict when faced with competing demands, or more specifically on attentional inhibitory control. From an evolutionary perspective, the circadian regulation of attentional inhibitory control is not only plausible, but advantageous. For instance, an optimal balance between respond (e.g., reactiv...

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Arousal facilitates involuntary eye movements

Cited by 20 publications

References 41 publications

Characterizing the electrophysiological abnormalities in visually reviewed normal EEGs of drug-resistant focal epilepsy patients

Characterizing the electrophysiological abnormalities in visually reviewed normal EEGs of drug-resistant focal epilepsy patients

The eyes reflect an internal cognitive state hidden in the population activity of cortical neurons

Differential Impact of Sleep Deprivation and Circadian Timing on Reflexive Versus Inhibitory Control of Attention

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