Eye blinks as a visual processing stage

Unsupervised identification of internal perceptual states influencing psychomotor performance

When humans perform repetitive tasks over long periods, their performance is not constant. People drift in and out of states that might be loosely categorised as engagement, disengagement or 'flow' and these states will be reflected in aspects of their performance (for example, reaction time, accuracy, criteria shifts and potentially longer-term strategy). Until recently it has been challenging to relate these behavioural states to the underlying neural mechanisms that generate them. Here, we acquired magnetoencephalograpy recordings and contemporaneous, dense behavioural data from participants performing an engaging task (Tetris) that required rapid, strategic behavioural responses over the period of an entire game. We asked whether it was possible to infer the presence of distinct behavioural states from the behavioural data and, if so, whether these states would have distinct neural correlates. We used hidden Markov Modelling to segment the behavioural time series into states with unique behavioural signatures, finding that we could identify three distinct and robust behavioural states. We then computed occipital alpha power across each state. These within-participant differences in alpha power were statistically significant, suggesting that individuals shift between behaviourally and neurally distinct states during complex performance, and that visuo-spatial attention change across these states.

Dataset combining EEG, eye-tracking, and high-speed video for ocular activity analysis across BCI paradigms

In Brain-Computer Interface (BCI) research, the detailed study of blinks is crucial. They can be considered as noise, affecting the efficiency and accuracy of decoding users' cognitive states and intentions, or as potential features, providing valuable insights into users' behavior and interaction patterns. We introduce a large dataset capturing electroencephalogram (EEG) signals, eye-tracking, high-speed camera recordings, as well as subjects' mental states and characteristics, to provide a multifactor analysis of eye-related movements. Four paradigms - motor imagery, motor execution, steady-state visually evoked potentials, and P300 spellers - are selected due to their capacity to evoke various sensory-motor responses and potential influence on ocular activity. This online-available dataset contains over 46 hours of data from 31 subjects across 63 sessions, totaling 2520 trials for each of the first three paradigms, and 5670 for P300. This multimodal and multi-paradigms dataset is expected to allow the development of algorithms capable of efficiently handling eye-induced artifacts and enhancing task-specific classification. Furthermore, it offers the opportunity to evaluate the cross-paradigm robustness involving the same participants.

Functional Vision Questionnaire Detects Near Triad Impairments in Adolescent Athletes With Concussion History

BACKGROUND

Concussions are mild traumatic brain injuries that often cause vision problems. They have significant impacts on everyday life, cognitive capacity, and sports performance, and may affect injury prevalence in fast contact sports such as ice hockey. A functional vision questionnaire specifically designed for sports was used here to study the correlation between vision problems and concussion history.

METHODS

In this national cross-sectional concussion study, 860 Finnish elite-level male adolescent ice hockey players (aged 13-21 years) answered a functional vision questionnaire and performed a computerized neurocognitive test, ImPACT. Totally 265 athletes reported a history of at least 1 concussion. All data were statistically compared with age-matched athletes with no concussion history (n = 595). For further analysis, athletes were divided into subgroups by age and number of previous concussions.

RESULTS

Previously concussed athletes reported more general and eye-specific symptoms than their healthy controls. Increases in eye fatigue, frontal headaches, and blinking were statistically significant. Also statistically more problems with depth perception and evaluating distances, concentration problems, blurred vision, and losing the object in sight were observed among athletes with concussion history.

CONCLUSIONS

Concussion history reflects an increase in the prevalence of vision deficits, as determined by multiple disturbances in the near triad. The significant number of vision problems in the concussion history groups strongly suggests that functional vision should routinely be evaluated in athletes. The vision problems observed in the athletes with concussion history may indicate an increased injury risk that should be addressed.

Consequences of eye movements for spatial selectivity

What determines spatial tuning in the visual system? Standard views rely on the assumption that spatial information is directly inherited from the relative position of photoreceptors and shaped by neuronal connectivity.1,2 However, human eyes are always in motion during fixation,3,4,5,6 so retinal neurons receive temporal modulations that depend on the interaction of the spatial structure of the stimulus with eye movements. It has long been hypothesized that these modulations might contribute to spatial encoding,7,8,9,10,11,12 a proposal supported by several recent observations.13,14,15,16 A fundamental, yet untested, consequence of this encoding strategy is that spatial tuning is not hard-wired in the visual system but critically depends on how the fixational motion of the eye shapes the temporal structure of the signals impinging onto the retina. Here we used high-resolution techniques for eye-tracking17 and gaze-contingent display control18 to quantitatively test this distinctive prediction. We examined how contrast sensitivity, a hallmark of spatial vision, is influenced by fixational motion, both during normal active fixation and when the spatiotemporal stimulus on the retina is altered to mimic changes in fixational control. We showed that visual sensitivity closely follows the strength of the luminance modulations delivered within a narrow temporal bandwidth, so changes in fixational motion have opposite visual effects at low and high spatial frequencies. By identifying a key role for oculomotor activity in spatial selectivity, these findings have important implications for the perceptual consequences of abnormal eye movements, the sources of perceptual variability, and the function of oculomotor control.