The impact of microsaccades on vision: towards a unified theory of saccadic function
TL;DR: This research shows that fixational eye movements thwart neural adaptation to unchanging stimuli and thus prevent and reverse perceptual fading during fixation, leading us towards a unified theory of saccadic and microsaccadic function.
Abstract: When we attempt to fix our gaze, our eyes nevertheless produce so-called 'fixational eye movements', which include microsaccades, drift and tremor. Fixational eye movements thwart neural adaptation to unchanging stimuli and thus prevent and reverse perceptual fading during fixation. Over the past 10 years, microsaccade research has become one of the most active fields in visual, oculomotor and even cognitive neuroscience. The similarities and differences between microsaccades and saccades have been a most intriguing area of study, and the results of this research are leading us towards a unified theory of saccadic and microsaccadic function.
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TL;DR: It is shown that LC activation reliably anticipates changes in pupil diameter that either fluctuate naturally or are driven by external events during near fixation, as in many psychophysical tasks.
876 citations
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...These fluctuations were not consistently associated with small eye movements (Martinez-Conde et al., 2013; Krekelberg, 2011), which occurred less frequently and without a consistent phase relationship with respect to the fluctuations in pupil diameter (Figure 2E)....
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TL;DR: In this review, the spectral, spatial, and temporal characteristics of muscle artifacts are compared with those described (so far) for high-frequency neural activity and several of the techniques that are being developed to help suppress muscle artifacts in MEG/EEG are reviewed.
Abstract: In recent years high-frequency brain activity in the gamma-frequency band (30–80 Hz) and above has become the focus of a growing body of work in MEG/EEG research. Unfortunately, high-frequency neural activity overlaps entirely with the spectral bandwidth of muscle activity (~20–300 Hz). It is becoming appreciated that artifacts of muscle activity may contaminate a number of non-invasive reports of high-frequency activity. In this review, the spectral, spatial, and temporal characteristics of muscle artifacts are compared with those described (so far) for high-frequency neural activity. In addition, several of the techniques that are being developed to help suppress muscle artifacts in MEG/EEG are reviewed. Suggestions are made for the collection, analysis, and presentation of experimental data with the aim of reducing the number of publications in the future that may contain muscle artifacts.
535 citations
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...…help with non-invasive investigations of the role highfrequency activity may play in eliciting microsaccades, or how high-frequency activity is affected by microsaccades (Bosman et al., 2009), which help to maintain the stability of images on the retina (Martinez-Conde et al., 2013)....
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TL;DR: It is concluded that eye tracking can reveal important features of the complex picture of autism.
Abstract: Eye tracking has the potential to characterize autism at a unique intermediate level, with links ‘down’ to underlying neurocognitive networks, as well as ‘up’ to everyday function and dysfunction. Because it is non-invasive and does not require advanced motor responses or language, eye tracking is particularly important for the study of young children and infants. In this article, we review eye tracking studies of young children with autism spectrum disorder (ASD) and children at risk for ASD. Reduced looking time at people and faces, as well as problems with disengagement of attention, appear to be among the earliest signs of ASD, emerging during the first year of life. In toddlers with ASD, altered looking patterns across facial parts such as the eyes and mouth have been found, together with limited orienting to biological motion. We provide a detailed discussion of these and other key findings and highlight methodological opportunities and challenges for eye tracking research of young children with ASD. We conclude that eye tracking can reveal important features of the complex picture of autism.
221 citations
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...neural mechanisms for some eye tracking measures have been established [80] (see also [106,107]), this is not the...
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TL;DR: This review describes four temporally and functionally dissociable stages of attention in visual search (preparation, guidance, selection, and identification).
210 citations
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References
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TL;DR: The visual processing needed to perform this highly demanding task can be achieved in under 150 ms, and ERP analysis revealed a frontal negativity specific to no-go trials that develops roughly 150 ms after stimulus onset.
Abstract: How long does it take for the human visual system to process a complex natural image? Subjectively, recognition of familiar objects and scenes appears to be virtually instantaneous, but measuring this processing time experimentally has proved difficult. Behavioural measures such as reaction times can be used, but these include not only visual processing but also the time required for response execution. However, event-related potentials (ERPs) can sometimes reveal signs of neural processing well before the motor output. Here we use a go/no-go categorization task in which subjects have to decide whether a previously unseen photograph, flashed on for just 20 ms, contains an animal. ERP analysis revealed a frontal negativity specific to no-go trials that develops roughly 150 ms after stimulus onset. We conclude that the visual processing needed to perform this highly demanding task can be achieved in under 150 ms.
3,284 citations
TL;DR: It has long been assumed that sensory neurons are adapted to the statistical properties of the signals to which they are exposed, but recent developments in statistical modeling have enabled researchers to study more sophisticated statistical models for visual images, to validate these models empirically against large sets of data, and to begin experimentally testing the efficient coding hypothesis.
Abstract: ▪ Abstract It has long been assumed that sensory neurons are adapted, through both evolutionary and developmental processes, to the statistical properties of the signals to which they are exposed. Attneave (1954), Barlow (1961) proposed that information theory could provide a link between environmental statistics and neural responses through the concept of coding efficiency. Recent developments in statistical modeling, along with powerful computational tools, have enabled researchers to study more sophisticated statistical models for visual images, to validate these models empirically against large sets of data, and to begin experimentally testing the efficient coding hypothesis for both individual neurons and populations of neurons.
2,280 citations
TL;DR: Overlapping regional networks in parietal, frontal, and temporal lobes were active in both tasks, consistent with the hypothesis that attentional and oculomotor processes are tightly integrated at the neural level.
1,599 citations
TL;DR: Current studies of fixational eye movements have focused on determining how visible perception is encoded by neurons in various visual areas of the brain to elucidate how the brain makes the authors' environment visible.
Abstract: Our eyes continually move even while we fix our gaze on an object. Although these fixational eye movements have a magnitude that should make them visible to us, we are unaware of them. If fixational eye movements are counteracted, our visual perception fades completely as a result of neural adaptation. So, our visual system has a built-in paradox — we must fix our gaze to inspect the minute details of our world, but if we were to fixate perfectly, the entire world would fade from view. Owing to their role in counteracting adaptation, fixational eye movements have been studied to elucidate how the brain makes our environment visible. Moreover, because we are not aware of these eye movements, they have been studied to understand the underpinnings of visual awareness. Recent studies of fixational eye movements have focused on determining how visible perception is encoded by neurons in various visual areas of the brain.
1,148 citations