Different States Of Attention Research Articles

Microsaccades as a marker not a cause for attention-related modulation.

Recent evidence suggests that microsaccades are causally linked to the attention-related modulation of neurons-specifically, that microsaccades toward the attended location are required for the subsequent changes in firing rate. These findings have raised questions about whether attention-related modulation is due to different states of attention as traditionally assumed or might instead be a secondary effect of microsaccades. Here, in two rhesus macaques, we tested the relationship between microsaccades and attention-related modulation in the superior colliculus (SC), a brain structure crucial for allocating attention. We found that attention-related modulation emerged even in the absence of microsaccades, was already present prior to microsaccades toward the cued stimulus, and persisted through the suppression of activity that accompanied all microsaccades. Nonetheless, consistent with previous findings, we also found significant attention-related modulation when microsaccades were directed toward, rather than away from, the cued location. Thus, despite the clear links between microsaccades and attention, microsaccades are not necessary for attention-related modulation, at least not in the SC. They do, however, provide an additional marker for the state of attention, especially at times when attention is shifting from one location to another.

Alpha EEG Activity and Pupil Diameter Coupling during Inactive Wakefulness in Humans.

Variations in human behavior correspond to the adaptation of the nervous system to different internal and environmental demands. Attention, a cognitive process for weighing environmental demands, changes over time. Pupillary activity, which is affected by fluctuating levels of cognitive processing, appears to identify neural dynamics that relate to different states of attention. In mice, for example, pupil dynamics directly correlate with brain state fluctuations. Although, in humans, alpha-band activity is associated with inhibitory processes in cortical networks during visual processing, and its amplitude is modulated by attention, conclusive evidence linking this narrowband activity to pupil changes in time remains sparse. We hypothesize that, as alpha activity and pupil diameter indicate attentional variations over time, these two measures should be comodulated. In this work, we recorded the electroencephalographic (EEG) and pupillary activity of 16 human subjects who had their eyes fixed on a gray screen for 1 min. Our study revealed that the alpha-band amplitude and the high-frequency component of the pupil diameter covariate spontaneously. Specifically, the maximum alpha-band amplitude was observed to occur ∼300 ms before the peak of the pupil diameter. In contrast, the minimum alpha-band amplitude was noted to occur ∼350 ms before the trough of the pupil diameter. The consistent temporal coincidence of these two measurements strongly suggests that the subject’s state of attention, as indicated by the EEG alpha amplitude, is changing moment to moment and can be monitored by measuring EEG together with the diameter pupil.

Influence of content and intensity of thought on behavioral and pupil changes during active mind-wandering, off-focus, and on-task states

Mind wandering (MW) is a pervasive phenomenon that occurs very frequently, regardless of the task. A content-based definition of MW holds that it occurs when the content of thought switches from an ongoing task and/or an external stimulus-driven event to self-generated or inner thoughts. A recent account suggests that the transition between these different states of attention occurs via an off-focus state. Following this suggestion, previous work relating MW to pupil size might have lumped attentional states that are critically different from each (i.e., off-focus and MW states). In the present study, both behavior and pupil size were measured during a sustained-attention-to-response task, to disentangle the content of thought (on task or MW) from an off-focus state of mind. The off-focus state was operationalized by probing the intensity with which participants were on task or mind-wandering. The results of two experiments showed that the behavioral and phasic pupillary responses were sensitive to changes related to the content of thought. The behavioral responses were furthermore related to the intensity of the thought. However, no clear relation between the different attentional states and tonic pupillary diameter was found, suggesting that it is an unreliable proxy for MW.

Comparison of brain effective connectivity in different states of attention and consciousness based on EEG signals

Evidence from recent studies on attention and consciousness has raised many questions about their inherent natures and the existence of a possible relationship between them. The main goal of this study is to investigate the significant difference among different states of attention and consciousness, through the connectivity method. These two cognitive phenomena have been studied in recent years with different approaches, but none of them has employed connectivity methods to study the attention and consciousness relationship. Therefore, the connectivity approach is a novel effort in this field. The 8-channel Electroencephalogram signal (EEGs) was used from 45 participants performing a psychophysical visual task. To track the variation of connectivity during time, the EEG recorded data were organized in a particular way, providing 9 1 s signals, including four stimuli classes: attention-consciousness class, attention-unconsciousness class, inattention-consciousness class, and inattention-unconsciousness class. In order to reduce the volume conduction effect, source signals were extracted with the ICA method. The effective connectivity network was computed using the Granger causality method. For the statistical analysis, connectivity indices were presented. This approach suggests that attention-consciousness and attention-unconsciousness classes, and attention-unconsciousness and inattention-unconsciousness classes are the most and least distinctive combinations, respectively. In a more general view provided by averaging the connectivity matrices, all the presented connectivity indices showed significant differences with p-value<0.05 for two combinations: 1-attention-consciousness and attention-unconsciousness classes, and 2- inattention-consciousness and inattention-unconsciousness classes.

An intelligent fitness diagnosis system using electroencephalogram with biomedical signals

This paper proposes an intelligent fitness diagnosis system (IFDS), which integrates the electroencephalogram (EEG) and electrocardiogram (ECG) biomedical signals and fitness data. IFDS detects the voltage and current produced by the users under different states of attention and meditation during exercise. Based on EEG, ECG, and fitness data, the extension method is applied to distinguish the physical and mental conditions of the users during exercise. The brainwave training system, designed by LabVIEW, analyzes the α and θ wave bands of EEG, and plots the waveforms under different states of attention and meditation simultaneously to effectively improve the users' attention. Ten subjects were included to exercise for 15 times, lasting 3 min each. The accuracy of IFDS reaches 91%. Meanwhile, IFDS indirectly diagnoses the symptoms of some diseases in the users. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley &amp; Sons, Inc.

Introduction and validation of a less painful algorithm to estimate the nociceptive flexion reflex threshold

The nociceptive flexion reflex (NFR) is a widely used tool to investigate spinal nociception for scientific and diagnostic purposes, but its clinical use is currently limited due to the painful measurement procedure, especially restricting its applicability for patients suffering from chronic pain disorders. Here we introduce a less painful algorithm to assess the NFR threshold. Application of this new algorithm leads to a reduction of subjective pain ratings by over 30% compared to the standard algorithm. We show that the reflex threshold estimates resulting from application of the new algorithm can be used interchangeably with those of the standard algorithm after adjusting for the constant difference between the algorithms. Furthermore, we show that the new algorithm can be applied at shorter interstimulus intervals than are commonly used with the standard algorithm, since reflex threshold values remain unchanged and no habituation effects occur when reducing the interstimulus interval for the new algorithm down to 3s. Finally we demonstrate the utility of the new algorithm to investigate the modulation of nociception through different states of attention. Taken together, the here presented new algorithm could increase the utility of the NFR for investigation of nociception in subjects who were previously not able to endure the measurement procedure, such as chronic pain patients.

Visual Attention Modulates Insight Versus Analytic Solving of Verbal Problems.

Behavioral and neuroimaging findings indicate that distinct cognitive and neural processes underlie solving problems with sudden insight. Moreover, people with less focused attention sometimes perform better on tests of insight and creative problem solving. However, it remains unclear whether different states of attention, within individuals, influence the likelihood of solving problems with insight or with analysis. In this experiment, participants (N = 40) performed a baseline block of verbal problems, then performed one of two visual tasks, each emphasizing a distinct aspect of visual attention, followed by a second block of verbal problems to assess change in performance. After participants engaged in a center-focused flanker task requiring relatively focused visual attention, they reported solving more verbal problems with analytic processing. In contrast, after participants engaged in a rapid object identification task requiring attention to broad space and weak associations, they reported solving more verbal problems with insight. These results suggest that general attention mechanisms influence both visual attention task performance and verbal problem solving.

Effects of Spatial Attention on Contrast Response Functions in Macaque Area V4

Previous single-unit studies of visual cortex have reported that spatial attention modulates responses to different orientations and directions proportionally, such that it does not change the width of tuning functions for these properties. Other studies have suggested that spatial attention causes a leftward shift in contrast response functions, such that its effects on responses to stimuli of different contrasts are not proportional. We have further explored the effects of attention on stimulus-response functions by measuring the responses of 131 individual V4 neurons in two monkeys while they did a task that controlled their spatial attention. Each neuron was tested with a set of stimuli that spanned complete ranges of orientation and contrast during different states of attention. Consistent with earlier reports, attention scaled responses to preferred and nonpreferred orientations proportionally. However, we did not find compelling evidence that the effects were best described by a leftward shift of the contrast response function. The modulation of neuronal responses by attention was well described by either a leftward shift or proportional scaling of the contrast response function. Consideration of differences in experimental design and analysis that may have contributed to this discrepancy suggests that it was premature to exclude a proportional scaling of responses to different contrasts by attention in favor of a leftward shift of contrast response functions. The current results reopen the possibility that the effects of attention on stimulus-response functions are well described by a single proportional increase in a neuron's response to all stimuli.

Regulation of sinus cardiac rhythm during different states of attention in full-term and preterm 5-month-old infants

Parasympathetic heart rate regulation was studied in full-term (FT) and very preterm (VPT) infants at the corrected age of 5 months during endogenous and exogenous sustained attention. Cardiac interval duration and the respiratory sinus arrhythmia (RSA) were used as indices of parasympathetic regulation of heart activity during infants’ sustained attention to a new visual stimulus (exogenous attention) and anticipatory attention to repeatedly appearing and disappearing stimuli in the visual expectation paradigm (endogenous attention). The psychomotor development and behavior regulation were assessed using the Bayley Scales of Infant Development, and the clinical risk was scored on the Ballard scale. A shift of attention state affected the RSA only in the FT infants. The endogenous attention was associated with a relatively high RSA level, with the higher RSA levels being significantly correlated with the Bayley Behavior Rating Scale scores. At the age of 5 months, the degree of clinical risk in the VPT infants was not correlated with specific features of parasympathetic regulation. The results are discussed in terms of the concepts of physiological mechanisms of exogenous and endogenous attention in infants. The central regulation of the autonomic functions during a shift of attention state is less efficient in healthy VPT infants as compared to their FT peers. The RSA reactivity can be a more sensitive indicator of CNS regulatory disorders than the standard indices of clinical risk.

Contingent Negative Variation and Attention in Schizophrenic and Depressed Patients

Contingent negative variation (CNV) is supposed to be a psychophysiological indicator of attention and arousal. Both have been reported to be deteriorated in schizophrenic and depressed patients. Thirty-four patients with major depression, 43 patients with schizophrenia and 49 healthy subjects were investigated during acute illness with a complex three-stimulus go/no-go task which requires different states of attention: trials consisted of three complex figures that were tachistoscopically presented. Three identical figures had to be confirmed by pressing a button (target condition). CNV was measured: (1) after the first figure waiting for the second (baseline condition), (2) after two identical figures waiting for the third (response-relevant condition), (3) after two different figures waiting for the third (response-irrelevant condition). The response-relevant condition compared to baseline significantly intensified CNV in healthy controls and to a minor extent in depressed patients but not in schizophrenics. In the response-relevant conditions in healthy controls, CNV was significantly reduced compared to the response-relevant condition. This clear discrimination between response-relevant and response-irrelevant conditions was not observed in either group of patients. Thus, the applied CNV paradigm was able to discriminate schizophrenic and depressed patients from healthy controls. Furthermore, subtle differences between schizophrenic and depressed patients were detected, reflected by the different CNV development across experimental conditions.