Background: Cognitive control is defined as the ability to act flexibly in the environment by either behaving automatically or inhibiting said automatic behaviour and it can be measured using an interleaved pro/anti-saccade task. Decline in cognitive control has been attributed to normal aging and neurological illnesses such as Parkinson’s disease (PD) as well as decline in other cognitive abilities. This parallel might highlight the role played by cognitive control in information processing and working memory. However, little is known about the relationship between cognitive control and other cognitive processes such as visual memory, decision making, and visual search. We thus propose to correlate the incidence of impaired cognitive control with deficits in visual memory, decision making and visual search in three groups: younger adults, older adults and patients with idiopathic PD.
Methods: Seventy-one participants, namely 34 adults (M =22.75, SD =3.8), 22 older adults (M =67.4, SD =8.3), and 20 PD patients (M =65.59, SD =8.2) performed four tasks: interleaved pro/anti-saccade, visual memory, decision making, and serial and pop-out visual search.
Results: Results show that within each group, anti-saccade error rate (ER) were significantly and negatively correlated with visual memory ER (ryounger =?0.378, P=0.036; rolder =?0.440, Polder =0.046; rPD =?0.609, P=0.016). On the other hand, correct decision-making reaction times (RT) were significantly correlated with anti-saccade ER, and RTs only in older adults (rER =0.529, P=0.014; rRT =0.512, P=0.018) and PD patients (rER =0.727, P=0.012; rRT =0.769, P=0.001). For visual search, PD patients showed a significant relationship between RTs for correct pro-saccades and pop-out (r=0.665, P=0.007), and serial (r=0.641, P=0.010) search RTs. Furthermore, there was a significant correlation between MoCA scores and anti-saccade RTs (r=?0.559, P=0.030) and ER (r=?0.562, P=0.029) in PD patients. Taken together, these results support the hypothesis of PD patients’ reliance on bottom-up processes as top-down processes decline. For younger adults, there was a significant correlation between serial search performance and both anti-saccade ER (r=0.488, P=0.005), and correct pro-saccade ER (r=0.413, P=0.021). In older adults, this relationship was absent, but anti-saccade ER significantly correlated with pop-out search times (r=0.473, P=0.030).
Conclusions: We found significant relationships between cognitive tasks and cognitive control as measured through the interleaved pro/anti-saccade task across and within participant groups, providing evidence of the appropriateness of the use of the interleaved pro/anti-saccade task as a measure of overall cognitive control.
Background: The goal of the present study was to determine whether exogenous attentional mechanisms involved in motor planning for saccades and reaches are the same for both effectors or are independent for each effector. We compared how eye and arm movement parameters, notably reaction time and amplitude, are affected by modulating exogenous attentional visual cues at different locations relative to a target.
Methods: Thirteen participants (M =22.8, SD =1.5) were asked to perform a task involving exogenous attentional allocation and movement planning. The participants were asked to fixate and maintain their hand at an initial position on a screen in front of them (left or right of screen centre) and then, at the disappearance of the fixation cross, perform an eye or arm movement, or both, to a target square (mirror location of fixation cross). A distractor appeared momentarily just before the appearance of the target at one of seven equidistant locations on the horizontal meridian. Saccade reaction times (SRTs), reach reaction times (RRTs) and amplitudes were calculated.
Results: Compared to the neutral condition (where no distractor was presented), distractors overall did not result in a facilitation of SRTs at any location (shorter SRTs), rather only a strong inhibition (longer SRTs) as a function of distractor target distance. In contrast, RRTs showed strong facilitation at the target location and less inhibition at further distances. However, both SRTs and RRTs followed a similar pattern in that RTs were shortest closer to the target position and were increasingly longer as a function of distractor target distance. In terms of amplitude, there was no effect of the distractor on reach endpoints, whereas, for saccades, there was an averaging effect of distractor position on saccade endpoints, but only for saccades with short SRTs. These effects were similar when either effector movement was performed alone or together.
Conclusions: These findings suggest that attentional selection mechanisms have both similar and differential effects on motor planning depending on the effectors used, providing evidence for both effector independent and effector dependent attentional selection mechanisms. This study furthers understanding of the operating mechanisms of exogenous attention on eye and arm movements and the interaction between sensory and motor systems.
Background: The concept of stochastic facilitation suggests that the addition of precise amounts of white noise can improve the perceptibility of a stimulus of weak amplitude. We know from previous research that tactile and auditory noise can facilitate visual perception, respectively. Here we wanted to see if the effects of stochastic facilitation generalise to a reaction time paradigm, and if reaction times are correlated with tactile thresholds. We know that when multiple sensory systems are stimulated simultaneously, reaction times are faster than either stimulus alone, and also faster than the sum of reaction times (known as the race model).
Methods: Five participants were re-tested in five blocks each of which contained a different background noise levels, randomly ordered across sessions. At each noise level, they performed a tactile threshold detection task and a tactile reaction time task.
Results: Both tactile threshold and tactile reaction times were significantly affected by the background white noise. While the preferred amplitude for the white noise was different for every participant, the average lowest threshold was obtained with white noise presented binaurally at 70 db. The reaction times were analysed by fitting an ex-Gaussian, the sum of a Gaussian function and an exponential decay function. The white noise significantly affected the exponential parameter (tau) in a way that is compatible with the facilitation of thresholds.
Conclusions: We therefore conclude that multisensory reaction time facilitation can, at least in part, be explained by stochastic facilitation of the neural signals.
Abstract: Navigation technology in ophthalmology, colloquially called “eye-tracking”, has been applied to various areas of eye care. This approach encompasses motion-based navigation technology in both ophthalmic imaging and treatment. For instance, modern imaging instruments use a real-time eye-tracking system, which helps to reduce motion artefacts and increase signal-to-noise ratio in imaging acquisition such as optical coherence tomography (OCT), microperimetry, and fluorescence and color imaging. Navigation in ophthalmic surgery has been firstly applied in laser vision corrective surgery and spread to involve navigated retinal photocoagulation, and positioning guidance of intraocular lenses (IOL) during cataract surgery. It has emerged as one of the most reliable representatives of technology as it continues to transform surgical interventions into safer, more standardized, and more predictable procedures with better outcomes. Eye-tracking is essential in refractive surgery with excimer laser ablation. Using this technology for cataract surgery in patients with high preoperative astigmatism has produced better therapeutic outcomes. Navigated retinal laser has proven to be safer and more accurate compared to the use of conventional slit lamp lasers. Eye-tracking has also been used in imaging diagnostics, where it is essential for proper alignment of captured zones of interest and accurate follow-up imaging. This technology is not routinely discussed in the ophthalmic literature even though it has been truly impactful in our clinical practice and represents a small revolution in ophthalmology.
