Visual Selective Attention Task Research Articles

Effect of L-theanine on selective attention in a traffic-related reaction task in sleep-deprived young adults: a double-blind placebo-controlled, crossover study

ABSTRACT Background L-theanine is a non-protein-forming amino acid found in tea. Limited evidence suggests that it improves selective attention. Sleep deprivation impairs attention and psychomotor reactions, affecting automobile driving. We aimed to determine whether L-theanine improves neurobehavioral measures of visual attention in acutely sleep-deprived healthy adults in a traffic-scene-based attention task. Methods In a double-blind, placebo-controlled, counterbalanced, two-way crossover study, we compared the effects of a 200-mg dose of L-theanine with a placebo (150 ml of distilled water) on a computerised, traffic-scene-based visual recognition reaction task in 24 healthy volunteers (age 20–25 years; 13 males) sleep-deprived overnight. The participants made speeded button-presses to imminent accident scenes (i.e. hits), while ignoring safe scenes. They were tested pre-dose and 45 min post-dose, each treatment administered one week apart. Results Hit rates were more than 90% in all sessions, and were similar in two treatments, pre- vs post-dose. L-theanine significantly reduced false alarms (i.e. responses to safe scenes) (p = 0.014) and increased A′ (i.e. target-distractor discriminability) (p = 0.009), whereas placebo did not (p > 0.05). L-theanine reduced hit reaction time by 38.65 ms (p = 0.007), and placebo by 19.08 ms (p = 0.016), however reaction time changes from baseline were not significantly different between treatments (p > 0.05). Conclusions L-theanine in high doses appears to improve selective visual attention by concurrently improving information processing speed and target-distractor discriminability in acutely sleep-deprived individuals. This is consistent with previous functional neuroimaging findings, where L-theanine suppressed distractor-processing and default-mode-network activity in visual selective attention tasks.

Nonverbal Executive Functioning in Relation to Vocabulary and Morphosyntax in Preschool Children With and Without Developmental Language Disorder.

Developmental language disorder (DLD) is characterized by persistent and unexplained difficulties in language development. Accumulating evidence shows that children with DLD also present with deficits in other cognitive domains, such as executive functioning (EF). There is an ongoing debate on whether exclusively verbal EF abilities are impaired in children with DLD or whether nonverbal EF is also impaired, and whether these EF impairments are related to their language difficulties. The aims of this study were to (a) compare nonverbal performance of preschoolers with DLD and typically developing (TD) peers, (b) examine how nonverbal EF and language abilities are related, and (c) investigate whether a diagnosis of DLD moderates the relationship between EF and language abilities. A total of 143 children (nDLD = 65, nTD = 78) participated. All children were between 3 and 6.5 years old and were monolingual Dutch. We assessed nonverbal EF with a visual selective attention task, a visuospatial short-term and working memory task, and a task gauging broad EF abilities. Vocabulary and morphosyntax were each measured with two standardized language tests. We created latent variables for EF, vocabulary, and morphosyntax. Analyses showed that children with DLD were outperformed by their TD peers on all nonverbal EF tasks. Nonverbal EF abilities were related to morphosyntactic abilities in both groups, whereas a relationship between vocabulary and EF skills was found in the TD group only. These relationships were not significantly moderated by a diagnosis of DLD. We found evidence for nonverbal EF impairments in preschool children with DLD. Moreover, nonverbal EF and morphosyntactic abilities were significantly related in these children. These findings may have implications for intervention and support the improvement of prognostic accuracy. https://doi.org/10.23641/asha.24121287.

Differential effects of walking across visual cortical processing stages

Perceptual processes are almost exclusively investigated and understood under marked movement restriction, while natural behaviour includes pronounced movements. Recent human studies have indicated a profound influence of body movement on early visual responses (e.g., evoked components around 100 msec in EEG, electroencephalogram). However, very little is known about the influence of free walking on later visual responses (e.g., responses related to visual selective attention in a later time window than the stimulus evoked N1 component). In the current study, we measured neural signals (EEG) and behavioural performance in a visual selective attention task while participants were standing or freely walking. The results showed that walking was associated with an amplification of early sensory-evoked potential as indicated by the N1 component. Interestingly, neural indexes of the succeeding processing stages of stimulus discrimination and identification, namely the N2pc component and alpha oscillations, and the eventual behavioural measures were comparable between standing and walking. Additionally, in both standing and walking conditions, an overall advantage in target processing for the right visual field was observed. Our work provides evidence that the early sensory processing is enhanced during locomotion while the succeeding processing steps in a later time window are not modulated by locomotion. We conclude that walking has differential effects across visual cortical processing stages.

Cortical oscillations that underlie visual selective attention are abnormal in adolescents with cerebral palsy

Adolescence is a critical period for the development and refinement of several higher-level cognitive functions, including visual selective attention. Clinically, it has been noted that adolescents with cerebral palsy (CP) may have deficits in selectively attending to objects within their visual field. This study aimed to evaluate the neural oscillatory activity in the ventral attention network while adolescents with CP performed a visual selective attention task. Adolescents with CP (N = 14; Age = 15.7 ± 4 years; MACS I–III; GMFCS I–IV) and neurotypical (NT) adolescents (N = 21; Age = 14.3 ± 2 years) performed the Eriksen flanker task while undergoing magnetoencephalographic (MEG) brain imaging. The participants reported the direction of a target arrow that was surrounded by congruent or incongruent flanking arrows. Compared with NT adolescents, adolescents with CP had slower responses and made more errors regarding the direction of the target arrow. The MEG results revealed that adolescents with CP had stronger alpha oscillations in the left insula when the flanking arrows were incongruent. Furthermore, participants that had more errors also tended to have stronger alpha oscillatory activity in this brain region. Altogether these results indicate that the aberrant activity seen in the left insula is associated with diminished visual selective attention function in adolescents with CP.

Predicting Grating Orientations With Cross-Frequency Coupling and Least Absolute Shrinkage and Selection Operator in V1 and V4 of Rhesus Monkeys.

Orientation selectivity, as an emergent property of neurons in the visual cortex, is of critical importance in the processing of visual information. Characterizing the orientation selectivity based on neuronal firing activities or local field potentials (LFPs) is a hot topic of current research. In this paper, we used cross-frequency coupling and least absolute shrinkage and selection operator (LASSO) to predict the grating orientations in V1 and V4 of two rhesus monkeys. The experimental data were recorded by utilizing two chronically implanted multi-electrode arrays, which were placed, respectively, in V1 and V4 of two rhesus monkeys performing a selective visual attention task. The phase–amplitude coupling (PAC) and amplitude–amplitude coupling (AAC) were employed to characterize the cross-frequency coupling of LFPs under sinusoidal grating stimuli with different orientations. Then, a LASSO logistic regression model was constructed to predict the grating orientation based on the strength of PAC and AAC. Moreover, the cross-validation method was used to evaluate the performance of the model. It was found that the average accuracy of the prediction based on the combination of PAC and AAC was 73.9%, which was higher than the predicting accuracy with PAC or AAC separately. In conclusion, a LASSO logistic regression model was introduced in this study, which can predict the grating orientations with relatively high accuracy by using PAC and AAC together. Our results suggest that the principle behind the LASSO model is probably an alternative direction to explore the mechanism for generating orientation selectivity.

Altered fronto-occipital connectivity during visual selective attention in regular cannabis users

Cognitive processing impairments have been associated with acute cannabis use, but there is mixed evidence regarding the cognitive effects of chronic cannabis use. Several neuroimaging studies have noted selective-attention processing differences in those who chronically use cannabis, but the neural dynamics governing the altered processing is unclear. Twenty-four adults reporting at least weekly cannabis use in the past 6months on the Cannabis Use Disorder Identification Test - Revised were compared to 24 demographically matched controls who reported no prior cannabis use. All participants completed a visual selective attention processing task while undergoing magnetoencephalography. Time-frequency windows of interest were identified using a data-driven method, and spectrally specific neural activity was imaged using a beamforming approach. All participants performed within normal range on the cognitive task. Regular cannabis users displayed an aberrant cognitive interference effect in the theta (4-8Hz) frequency range shortly after stimulus onset (i.e., 0-250ms) in the right occipital cortex. Cannabis users also exhibited altered functional connectivity between the right prefrontal cortex and right occipital cortices in comparison to controls. Individuals with a history of regular cannabis use exhibited abnormal theta interference activity in the occipital cortices, as well as altered prefrontal-occipital functional connectivity in the theta range during a visual selective attention task. Such differences may reflect compensatory processing, as these participants performed within normal range on the task. Understanding the neural dynamics in chronic, regular cannabis users may provide insight on how long-term and/or frequent use may affect neural networks underlying cognitive processes.

The role of attention in listening-in-noise

Listeners of all ages are faced with having to understand speech in the presence of noise. One factor that might influence listeners' success at this task is their ability to attend selectively. We examine both adults' and toddlers' understanding of speech in the presence of nonlinguistic background noise – noise that is either easier or harder to attend to selectively. We also test the same individuals on a nonlinguistic selective attention task. Adult listeners easily take advantage of acoustic cues such as spatial location and frequency-range differences to help them attend selectively to, and comprehend, the target speech. Young toddlers (under 2 years of age) fail to use these cues. In addition, among adults, success at listening in noise is correlated with performance in a visual selective attention task, suggesting that domain-general attention skills are relevant for adults' listening in noise. This is less clearly the case for young children, however; indeed, children who were more easily distracted by extraneous sounds showed better speech understanding in noise. These findings suggest that the relationship between performance in challenging listening conditions and other cognitive skills undergoes critical changes across development.

Visual exogenous and endogenous attention and visual memory in preschool children who stutter

PurposeAttention develops gradually from infancy to the preschool years and beyond. Exogenous attention, consisting of automatic responses to salient stimuli, develops in infancy, whereas endogenous attention, or voluntary attention, begins to develop later, in the preschool years. The purpose of this study was to examine (a) exogenous and endogenous attention in young children who stutter (CWS) and children who do not stutter (CWNS) through two conditions of a visual sustained selective attention task, and (b) visual short-term memory (STM) between groups within the context of this task. Method42 CWS and 42 CWNS, ages 3;0–5;5 (years;months), were pair-matched in age, gender (31 males, 11 females per group), and socioeconomic status. Children completed a visual tracking task (Track-It Task; Fisher et al., 2013) requiring sustained selective attention and engaging exogenous and endogenous processes. Following each item, children were asked to recall the item they had tracked, as a memory check. ResultsThe CWS group demonstrated significantly less accuracy in overall tracking and visual memory for the tracked stimuli, compared to the CWNS group. Across groups, the children performed better in sustained selective attention when the target stimuli were more salient (the condition tapping both exogenous and endogenous attention) than when stimuli were less so (the condition tapping primarily endogenous processes). ConclusionsRelative to peers, preschool-age CWS, as a group, display weaknesses in visual sustained selective attention and visual STM.

Computational modelling of attentional selectivity in depression reveals perceptual deficits.

Depression is associated with broad deficits in cognitive control, including in visual selective attention tasks such as the flanker task. Previous computational modelling of depression and flanker task performance showed reduced pre-potent response bias and reduced executive control efficiency in depression. In the current study, we applied two computational models that account for the full dynamics of attentional selectivity. Across three large-scale online experiments (one exploratory experiment followed by two confirmatory - and pre-registered - experiments; total N = 923), we measured attentional selectivity via the flanker task and obtained measures of depression symptomology as well as anhedonia. We then fit two computational models that account for the dynamics of attentional selectivity: The dual-stage two-phase model, and the shrinking spotlight (SSP) model. No behavioural measures were related to depression symptomology or anhedonia. However, a parameter of the SSP model that indexes the strength of perceptual input was consistently negatively associated with the magnitude of depression symptomatology. The findings provide evidence for deficits in perceptual representations in depression. We discuss the implications of this in relation to the hypothesis that perceptual deficits potentially exacerbate control deficits in depression.

Dissociable Effects of Reward on P300 and EEG Spectra Under Conditions of High vs. Low Vigilance During a Selective Visual Attention Task.

The influence of motivation on selective visual attention in states of high vs. low vigilance is poorly understood. To explore the possible differences in the influence of motivation on behavioral performance and neural activity in high and low vigilance levels, we conducted a prolonged 2 h 20 min flanker task and provided monetary rewards during the 20- to 40- and 100- to 120-min intervals of task performance. Both the behavioral and electrophysiological measures were modulated by prolonged task engagement. Moreover, the effect of reward was different in high vs. low vigilance states. The monetary reward increased accuracy and decreased the reaction time (RT) and number of omitted responses in the low but not in the high vigilance state. The fatigue-related decrease in P300 amplitude recovered to its level in the high vigilance state by manipulating motivation, whereas the fatigue-related increase in P300 latency was not modulated by reward. Additionally, the fatigue-related increase in event-related spectral power at 1–4 Hz was sensitive to vigilance decrement and reward. However, the spectral power at 4–8 Hz was only affected by the decrease in vigilance. These electrophysiological measures were not influenced by motivation in the state of high vigilance. Our results suggest that neural processing capacity, but not the timing of processing, is sensitive to motivation. These findings also imply that the fatigue-related impairments in behavioral performance and neural activity underlying selective visual attention only partly recover after manipulating motivation. Furthermore, our results provide evidence for the dissociable neural mechanisms underlying the fatigue-related decrease vs. reward-related increase in attentional resources.

Characterizing the orientation selectivity in V1 and V4 of macaques by quadratic phase coupling

Objective. Orientation selectivity is one of the significant characteristics of neurons in the primary visual cortex (V1). Some neurons in extrastriate visual cortical areas also exhibit certain orientation selectivity. But it is still not well understood that how the orientation selectivity generates. Most previous studies about the orientation selectivity are based on the spike firing rate. However, the spikes are prone to be biased by the detection and sorting algorithms. Then, in this paper, the local field potential (LFP) is adopted to investigate the mechanism of orientation selectivity. Approach. We used the quadratic phase coupling (QPC), which was calculated by wavelet bicoherence, to describe the characteristics of orientation selectivity available in V1 and V4. The raw wideband neural signals were recorded by two chronically implanted multi-electrode arrays, which were placed in V1 and V4 respectively in two macaques performing a selective visual attention task. Main results. There is a strong correlation between the total bicoherence (TotalBic), which is a quantization for the overall QPC of frequency pairs in gamma band, and the grating orientation. Furthermore, the QPC distribution at the non-preferred orientation is mainly concentrated in the low frequencies (30–40 Hz) of gamma; while the QPC distribution at the preferred orientation concentrates in both the low frequencies and high frequencies (60–80 Hz) of gamma. In addition, the TotalBic of the gamma-band LFP between V1 and V4 varies with the grating orientations, indicating that the QPC is available in the feedforward link and the gamma-band LFP in V1 modulates the QPC in V4. Significance. The QPC reflects the orientations of the sinusoidal grating and describes the interaction of gamma-band LFP between different brain regions. Our results suggest that the QPC is an alternative avenue to explore the mechanism for generating orientation selectivity of visual neurons effectively.

Effects of Visual Scene Complexity on Neural Signatures of Spatial Attention.

Spatial selective attention greatly affects our processing of complex visual scenes, yet the way in which the brain selects relevant objects while suppressing irrelevant objects is still unclear. Evidence of these processes has been found using non-invasive electroencephalography (EEG). However, few studies have characterized these measures during attention to dynamic stimuli, and little is known regarding how these measures change with increased scene complexity. Here, we compared attentional modulation of the EEG N1 and alpha power (oscillations between 8–14 Hz) across three visual selective attention tasks. The tasks differed in the number of irrelevant stimuli presented, but all required sustained attention to the orientation trajectory of a lateralized stimulus. In scenes with few irrelevant stimuli, top-down control of spatial attention is associated with strong modulation of both the N1 and alpha power across parietal-occipital channels. In scenes with many irrelevant stimuli in both hemifields, however, top-down control is no longer represented by strong modulation of alpha power, and N1 amplitudes are overall weaker. These results suggest that as a scene becomes more complex, requiring suppression in both hemifields, the neural signatures of top-down control degrade, likely reflecting some limitation in EEG to represent this suppression.

High-definition transcranial direct current stimulation dissociates fronto-visual theta lateralization during visual selective attention.

Visual attention involves discrete multispectral oscillatory responses in visual and 'higher-order' prefrontal cortices. Prefrontal cortex laterality effects during visual selective attention are poorly characterized. High-definition transcranial direct current stimulation dynamically modulated right-lateralized fronto-visual theta oscillations compared to those observed in left fronto-visual pathways. Increased connectivity in right fronto-visual networks after stimulation of the left dorsolateral prefrontal cortex resulted in faster task performance in the context of distractors. Our findings show clear laterality effects in theta oscillatory activity along prefrontal-visual cortical pathways during visual selective attention. Studies of visual attention have implicated oscillatory activity in the recognition, protection and temporal organization of attended representations in visual cortices. These studies have also shown that higher-order regions such as the prefrontal cortex are critical to attentional processing, but far less is understood regarding prefrontal laterality differences in attention processing. To examine this, we selectively applied high-definition transcranial direct current stimulation (HD-tDCS) to the left or right dorsolateral prefrontal cortex (DLPFC). We predicted that HD-tDCS of the left versus right prefrontal cortex would differentially modulate performance on a visual selective attention task, and alter the underlying oscillatory network dynamics. Our randomized crossover design included 27 healthy adults that underwent three separate sessions of HD-tDCS (sham, left DLPFC and right DLPFC) for 20min. Following stimulation, participants completed an attention protocol during magnetoencephalography. The resulting oscillatory dynamics were imaged using beamforming, and peak task-related neural activity was subjected to dynamic functional connectivity analyses to evaluate the impact of stimulation site (i.e. left and right DLPFC) on neural interactions. Our results indicated that HD-tDCS over the left DLPFC differentially modulated right fronto-visual functional connectivity within the theta band compared to HD-tDCS of the right DLPFC and further, specifically modulated the oscillatory response for detecting targets among an array of distractors. Importantly, these findings provide network-specific insight into the complex oscillatory mechanisms serving visual selective attention.

Interactive effects of HIV and ageing on neural oscillations: independence from neuropsychological performance.

HIV infection is associated with increased age-related co-morbidities including cognitive deficits, leading to hypotheses of HIV-related premature or accelerated ageing. Impairments in selective attention and the underlying neural dynamics have been linked to HIV-associated neurocognitive disorder; however, the effect of ageing in this context is not yet understood. Thus, the current study aimed to identify the interactive effects of ageing and HIV on selective attention processing. A total of 165 participants (92 controls, 73 participants with HIV) performed a visual selective attention task while undergoing magnetoencephalography and were compared cross-sectionally. Spectrally specific oscillatory neural responses during task performance were imaged and linked with selective attention function. Reaction time on the task and regional neural activity were analysed with analysis of covariance (ANCOVA) models aimed at examining the age-by-HIV interaction term. Finally, these metrics were evaluated with respect to clinical measures such as global neuropsychological performance, duration of HIV infection and medication regimen. Reaction time analyses showed a significant HIV-by-age interaction, such that in controls older age was associated with greater susceptibility to attentional interference, while in participants with HIV, such susceptibility was uniformly high regardless of age. In regard to neural activity, theta-specific age-by-HIV interaction effects were found in the prefrontal and posterior parietal cortices. In participants with HIV, neuropsychological performance was associated with susceptibility to attentional interference, while time since HIV diagnosis was associated with parietal activity above and beyond global neuropsychological performance. Finally, current efavirenz therapy was also related to increased parietal interference activity. In conclusion, susceptibility to attentional interference in younger participants with HIV approximated that of older controls, suggesting evidence of HIV-related premature ageing. Neural activity serving attention processing indicated compensatory recruitment of posterior parietal cortex as participants with HIV infection age, which was related to the duration of HIV infection and was independent of neuropsychological performance, suggesting an altered trajectory of neural function.

The Orientation Selectivity of Spike-LFP Synchronization in Macaque V1 and V4.

Orientation selectivity is a fundamental property of visual cortical neurons and plays a crucial role in pattern perception. Although many studies have dedicated to explain how the orientation selectivity emerged, the mechanism underlying orientation selectivity is still not clear. In this work, we investigated the synchronization between spikes and local field potentials (LFP) in gamma band, with the aim of providing a new avenue to analyze the orientation selectivity. The experimental data were recorded by utilizing two chronically implanted multi-electrode arrays, where each array consisted of 48 electrodes and was placed over V1 and V4, respectively, in two macaques performing a selective visual attention task. An unbiased and robust measure for quantifying the synchronization between spikes and LFP was employed in the analysis process, which is termed as spike-triggered correlation matrix synchronization (SCMS) and performs reliably for limited samples of data. We observed the spike-LFP synchronization in three cases, i.e., spikes and LFP in V1, spikes and LFP in V4, spikes in V4 and LFP in V1. From the orientation tuning curves based on the spike-LFP synchronization, it is found that there is a strong correlation between the synchronization and grating orientation. The neurons in both V1 and V4 exhibit orientation selectivity, but V1 is stronger. In addition, the spike-LFP synchronization strength between V1 and V4 also shows orientation selectivity to drifting gratings. It means that the synchronization not only reflects the basic features of visual stimulation, but also describes the orientation tuning characteristics of neurons in different regions. Our results suggest that the spike-LFP synchronization can be used as an alternative and effective method to study the mechanism for generating orientation selectivity of visual neurons.

Blast exposure in the military and its effects on sensory and cognitive auditory processing

Blast-induced traumatic brain injury (TBI) and hearing loss are the two most common types of injuries sustained by military personnel while serving in the U.S. Global War on Terrorism. Recently several VA audiology clinics have reported active duty service members complaining of having problems communicating in noisy listening environments despite having normal to near-normal pure tone thresholds. In addition to standard clinical measures, we used electroencephalography (EEG) to determine whether damage to suprathreshold responding auditory nerve fibers in the sensory periphery and/or trauma to cortical regions associated with attention and working memory were responsible for the reported listening complications. In separate auditory and visual selective attention tasks, behavioral and neural measures suggest no evidence of long term neurotrauma affecting normal cognitive function. We found while absolute measures of auditory brainstem encoding varied greatly in all study subjects, comparisons of how the envelope following response (EFR) changes with modulation depth hint at differences between blast and non-blast exposed service members. These findings are consistent with audiometric threshold and distortion product otoacoustic emission data that show subtle differences between groups within clinically defined normal limits. Taken together these results suggest subclinical differences in audiometric measures might explain differences in suprathreshold listening.

Neural dynamics of selective attention deficits in HIV-associated neurocognitive disorder.

ObjectiveTo identify the neural markers of attention dysfunction in patients with HIV-associated neurocognitive disorder (HAND).MethodsSixty participants, including 40 HIV-infected adults (half with HAND) and 20 demographically matched controls performed a visual selective attention task while undergoing high-density magnetoencephalography. Neuronal activity related to selective attention processing was quantified and compared across the 3 groups, and correlated with neuropsychological measures of attention and executive function. Spontaneous neural activity was also extracted from these attention-related cortical areas and examined with respect to HAND status.ResultsHIV-infected participants with and without HAND exhibited behavioral selective attention deficits on the magnetoencephalography task, as indicated by an increased flanker effect. Neuronal measures of flanker interference activity in the alpha and theta range revealed differential dynamics in attention-related brain areas across the 3 groups, especially in those with HAND. In addition, theta range flanker interference activity in the left inferior frontal and dorsolateral prefrontal cortex was associated with executive function and attention composite scores, respectively. Progressively stronger spontaneous alpha and theta activity was also found in unimpaired HIV-infected and HAND participants relative to controls across brain regions implicated in different components of attention processing.ConclusionsBehavioral and neuronal metrics of selective attention performance distinguish participants with HAND from controls and unimpaired HIV-infected participants. These metrics, along with measures of local spontaneous neural activity, may hold promise as early markers of cognitive decline in participants with HIV infection and be useful prognostic indicators for HAND.

Practice makes perfect: High performance gains in older adults engaged in selective attention within and across sensory modalities

Selective attention has been found to decline with aging, possibly depending on the sensory modality through which targets and distractors are presented. We investigated the capacity of older adults to improve performance on visual and auditory selective attention tasks. 31 younger (mean age = 22.8 years, SD = 2.1) and 29 older participants (mean age = 69.5 years, SD = 5.8) performed visual and auditory tasks with and without unimodal and cross-modal distraction across five practice sessions. Reaction time decreased with practice in both age groups. Strikingly, this performance improvement was similar across the age groups. Moreover, distractor modality did not affect performance gains in either age group. Older adults were disproportionally affected by cross-modal visual distraction, however, corroborating previous studies. This age-related effect was mitigated during the practice sessions. Finally, there was no transfer of practice to neuropsychological test performance. These results suggest a high capacity of older individuals to improve selective attention functions within and across sensory modalities.

Altered Neural Dynamics during a Flanker Attention Task in Patients with Type 1 Diabetes

Background: Patients with type 1 diabetes appear to have deficits in specific cognitive domains, particularly in attention and executive function (1). In this study, we used magnetoencephalography (MEG; 2), a noninvasive functional neuroimaging method, to identify neuronal changes in attention processing in otherwise healthy young adults with type 1 diabetes during euglycemia. Methods: Adults with type 1 diabetes and no micro- or macro-vascular complications (N = 38) completed a visual selective attention task during MEG. A demographically-matched control group without type 1 diabetes was used for comparison. Each trial began with a fixation cross presented centrally, followed by a row of 5 arrows. Participants were asked to respond regarding the direction of the middle arrow (right index finger for left, right middle finger for right) and ignore the flanking arrows that were presented in either the same (congruent condition) or opposite direction (incongruent condition). All MEG data was processed following standard protocols (3), and the resulting images of functional brain activity were examined statistically. Results: While no differences in reaction time or accuracy were found between groups, patients recruited a more widespread network of task relevant brain regions compared to controls, particularly the prefrontal cortex and anterior cingulate. Patients had a greater alpha increase from baseline in the anterior cingulate (p < .01), an important brain region in attention, and in the prefrontal cortex (p < .01) as compared to controls, likely reflecting compensatory mechanisms at play. Conclusions: These results indicate that type 1 diabetes affects neural activity in attention networks of patients who are otherwise healthy and without major comorbidities, reflecting the recruitment of compensatory neural responses to complete task goals. Disclosure C.M. Embury: None. T.J. McDermott: None. A.I. Wiesman: None. K. Brau: None. C. Desouza: Consultant; Self; Novo Nordisk A/S, Sanofi. Research Support; Self; Merck & Co., Inc.. Advisory Panel; Self; Medscape. A. Drincic: None. T.W. Wilson: None.

A theta rhythm in macaque visual cortex and its attentional modulation

Theta rhythms govern rodent sniffing and whisking, and human language processing. Human psychophysics suggests a role for theta also in visual attention. However, little is known about theta in visual areas and its attentional modulation. We used electrocorticography (ECoG) to record local field potentials (LFPs) simultaneously from areas V1, V2, V4, and TEO of two macaque monkeys performing a selective visual attention task. We found a ≈4-Hz theta rhythm within both the V1-V2 and the V4-TEO region, and theta synchronization between them, with a predominantly feedforward directed influence. ECoG coverage of large parts of these regions revealed a surprising spatial correspondence between theta and visually induced gamma. Furthermore, gamma power was modulated with theta phase. Selective attention to the respective visual stimulus strongly reduced these theta-rhythmic processes, leading to an unusually strong attention effect for V1. Microsaccades (MSs) were partly locked to theta. However, neuronal theta rhythms tended to be even more pronounced for epochs devoid of MSs. Thus, we find an MS-independent theta rhythm specific to visually driven parts of V1-V2, which rhythmically modulates local gamma and entrains V4-TEO, and which is strongly reduced by attention. We propose that the less theta-rhythmic and thereby more continuous processing of the attended stimulus serves the exploitation of this behaviorally most relevant information. The theta-rhythmic and thereby intermittent processing of the unattended stimulus likely reflects the ecologically important exploration of less relevant sources of information.