Changes In Neural Activity Research Articles

Robust Coding of Eye Position in Posterior Parietal Cortex despite Context-Dependent Tuning.

Neurons in posterior parietal cortex (PPC) encode many aspects of the sensory world (e.g., scene structure), the posture of the body, and plans for action. For a downstream computation, however, only some of these dimensions are relevant; the rest are "nuisance variables" because their influence on neural activity changes with sensory and behavioral context, potentially corrupting the read-out of relevant information. Here we show that a key postural variable for vision (eye position) is represented robustly in male macaque PPC across a range of contexts, although the tuning of single neurons depended strongly on context. Contexts were defined by different stages of a visually guided reaching task, including (1) a visually sparse epoch, (2) a visually rich epoch, (3) a "go" epoch in which the reach was cued, and (4) during the reach itself. Eye position was constant within trials but varied across trials in a 3 × 3 grid spanning 24° × 24°. Using demixed principal component analysis of neural spike-counts, we found that the subspace of the population response encoding eye position is orthogonal to that encoding task context. Accordingly, a context-naive (fixed-parameter) decoder was nevertheless able to estimate eye position reliably across contexts. Errors were small given the sample size (∼1.78°) and would likely be even smaller with larger populations. Moreover, they were comparable to that of decoders that were optimized for each context. Our results suggest that population codes in PPC shield encoded signals from crosstalk to support robust sensorimotor transformations across contexts.SIGNIFICANCE STATEMENT Neurons in posterior parietal cortex (PPC) which are sensitive to gaze direction are thought to play a key role in spatial perception and behavior (e.g., reaching, navigation), and provide a potential substrate for brain-controlled prosthetics. Many, however, change their tuning under different sensory and behavioral contexts, raising the prospect that they provide unreliable representations of egocentric space. Here, we analyze the structure of encoding dimensions for gaze direction and context in PPC during different stages of a visually guided reaching task. We use demixed dimensionality reduction and decoding techniques to show that the coding of gaze direction in PPC is mostly invariant to context. This suggests that PPC can provide reliable spatial information across sensory and behavioral contexts.

Fatigue during Prolonged Simulated Driving: An Electroencephalogram Study

Fatigue resulting from driving has been the subject of interest in many studies, particularly due to its pertinent role in road traffic crashes. Fatigue can be evaluated by certain indicators, such as changes in neural activity. The objective of

A conceptual analysis of typological distance and its potential consequences on the bilingual brain

ABSTRACT With the increasing consensus that a single effect of bilingualism is unlikely, some scholars shift their focus to elements that may exert an influence on the bilingual brain. One such element that has been garnering attention lately concerns the role of L1-L2 typological distance. In this conceptual analysis, I make the case that the foundations to commence this discussion are still weak at this juncture; conceptualisations of what qualifies as ‘typologically similar’ or ‘distant’ are not well-established in bilingualism research, and the tendency to compare languages as wholes, without considering dimensions and degrees of linguistic difference, can be problematic. Further, reflections on how bilingual cognitive demands are formed and how they are linked to L2 skill engagement (i.e. receptive/productive skills) are rudimentary yet underpowered. Crucially, I highlight the ongoing need to meticulously interpret bilingual neural activity and neurostructural changes before conclusions on the influence of typological distance can be reached. I conclude my critique by proposing a conceptual framework – one that addresses language, cognition, and empirical methods in sequential order – to help us embark more effectively on the theoretical inquiry of whether L1-L2 typological distance can pose an influence on the bilingual brain.

Disrupted connectivity in the olfactory bulb-entorhinal cortex-dorsal hippocampus circuit is associated with recognition memory deficit in Alzheimer\u2019s disease model

Neural synchrony in brain circuits is the mainstay of cognition, including memory processes. Alzheimer's disease (AD) is a progressive neurodegenerative disorder that disrupts neural synchrony in specific circuits, associated with memory dysfunction before a substantial neural loss. Recognition memory impairment is a prominent cognitive symptom in the early stages of AD. The entorhinal–hippocampal circuit is critically engaged in recognition memory and is known as one of the earliest circuits involved due to AD pathology. Notably, the olfactory bulb is closely connected with the entorhinal–hippocampal circuit and is suggested as one of the earliest regions affected by AD. Therefore, we recorded simultaneous local field potential from the olfactory bulb (OB), entorhinal cortex (EC), and dorsal hippocampus (dHPC) to explore the functional connectivity in the OB-EC-dHPC circuit during novel object recognition (NOR) task performance in a rat model of AD. Animals that received amyloid-beta (Aβ) showed a significant impairment in task performance and a marked reduction in OB survived cells. We revealed that Aβ reduced coherence and synchrony in the OB-EC-dHPC circuit at theta and gamma bands during NOR performance. Importantly, our results exhibit that disrupted functional connectivity in the OB-EC-dHPC circuit was correlated with impaired recognition memory induced by Aβ. These findings can elucidate dynamic changes in neural activities underlying AD, helping to find novel diagnostic and therapeutic targets.

Effect of Second Language Proficiency on Inhibitory Control in the Simon Task: An fMRI Study.

How learning a second language (L2) changes our brain has been an important question in neuroscience. Previous neuroimaging studies with different ages and language pairs spoken by bilinguals have consistently shown plastic changes in brain systems supporting executive control. One hypothesis posits that L2 experience-induced neural changes supporting cognitive control, which is responsible for the selection of a target language and minimization of interference from a non-target language. However, it remains poorly understood as to whether such cognitive advantage is reflected as stronger controlled processing or increased automatic inhibition processing. In this study, using functional MRI we scanned 27 Chinese-English late bilinguals while they performed a Simon task. Results showed that bilinguals with higher L2 vocabulary proficiency performed better in the Simon task, and more importantly, higher L2 vocabulary proficiency was associated with weaker activation of brain regions that support more general cognitive control, including the right anterior cingulate cortex, left insula and left superior temporal gyrus. These results suggest that L2 experience may lead to a more automatic and efficient processing in the inhibitory control task. Our finding provides an insight into neural activity changes associated with inhibitory control as a function of L2 proficiency.

Spatiotemporal patterns of population response in the visual cortex under isoflurane: from wakefulness to loss of consciousness.

Anesthetic drugs are widely used in medicine and research to mediate loss of consciousness (LOC). Isoflurane is a commonly used anesthetic drug; however, its effects on cortical sensory processing, in particular around LOC, are not well understood. Using voltage-sensitive dye imaging, we measured visually evoked neuronal population response from the visual cortex in awake and anesthetized mice at 3 increasing concentrations of isoflurane, thus controlling the level of anesthesia from wakefulness to deep anesthesia. At low concentration of isoflurane, the effects on neuronal measures were minor relative to the awake condition. These effects augmented with increasing isoflurane concentration, while around LOC point, they showed abrupt and nonlinear changes. At the network level, we found that isoflurane decreased the stimulus-evoked intra-areal spatial spread of local neural activation, previously reported to be mediated by horizontal connections, and also reduced intra-areal synchronization of neuronal population. The synchronization between different visual areas decreased with higher isoflurane levels. Isoflurane reduced the population response amplitude and prolonged their latencies while higher visual areas showed increased vulnerability to isoflurane concentration. Our results uncover the changes in neural activity and synchronization at isoflurane concentrations leading to LOC and suggest reverse hierarchical shutdown of cortical areas.

Alteration of Neural Network Activity With Aging Focusing on Temporal Complexity and Functional Connectivity Within Electroencephalography.

With the aging process, brain functions, such as attention, memory, and cognitive functions, degrade over time. In a super-aging society, the alteration of neural activity owing to aging is considered crucial for interventions for the prevention of brain dysfunction. The complexity of temporal neural fluctuations with temporal scale dependency plays an important role in optimal brain information processing, such as perception and thinking. Complexity analysis is a useful approach for detecting cortical alteration in healthy individuals, as well as in pathological conditions, such as senile psychiatric disorders, resulting in changes in neural activity interactions among a wide range of brain regions. Multi-fractal (MF) and multi-scale entropy (MSE) analyses are known methods for capturing the complexity of temporal scale dependency of neural activity in the brain. MF and MSE analyses exhibit high accuracy in detecting changes in neural activity and are superior with regard to complexity detection when compared with other methods. In addition to complex temporal fluctuations, functional connectivity reflects the integration of information of brain processes in each region, described as mutual interactions of neural activity among brain regions. Thus, we hypothesized that the complementary relationship between functional connectivity and complexity could improve the ability to detect the alteration of spatiotemporal patterns observed on electroencephalography (EEG) with respect to aging. To prove this hypothesis, this study investigated the relationship between the complexity of neural activity and functional connectivity in aging based on EEG findings. Concretely, MF and MSE analyses were performed to evaluate the temporal complexity profiles, and phase lag index analyses assessing the unique profile of functional connectivity were performed based on the EEGs conducted for young and older participants. Subsequently, these profiles were combined through machine learning. We found that the complementary relationship between complexity and functional connectivity improves the classification accuracy among aging participants. Thus, the outcome of this study could be beneficial in formulating interventions for the prevention of age-related brain dysfunction.

Alterations of Prefrontal-Posterior Information Processing Patterns in Autism Spectrum Disorders.

Autism spectrum disorder (ASD) is a heterogeneous disorder characterized by different levels of repetitive and stereotypic behavior as well as deficits in social interaction and communication. In this current study, we explored the changes in cerebral neural activities in ASD. The purpose of this study is to investigate whether there exists a dysfunction of interactive information processing between the prefrontal cortex and posterior brain regions in ASD. We investigated the atypical connectivity and information flow between the prefrontal cortex and posterior brain regions in ASD utilizing the entropy connectivity (a kind of directional connectivity) method. Eighty-nine patients with ASD and 94 typical developing (TD) teenagers participated in this study. Two-sample t-tests revealed weakened interactive entropy connectivity between the prefrontal cortex and posterior brain regions. This result indicates that there exists interactive prefrontal-posterior underconnectivity in ASD, and this disorder might lead to less prior knowledge being used and updated. Our proposals highlighted that aforementioned atypical change might accelerate the deoptimization of brain networks in ASD.

Acupuncture Treatment Decreased Temporal Variability of Dynamic Functional Connectivity in Chronic Tinnitus.

Acupuncture is recommended for the relief of chronic tinnitus in traditional Chinese medicine, but the underlying neural mechanism remains unclear. The human brain is a dynamic system, and it’s unclear about acupuncture’s effects on the dynamic functional connectivity (DFC) of chronic tinnitus. Therefore, this study based on resting-state functional magnetic resonance imaging (fMRI) investigates abnormal DFC in chronic tinnitus patients and the neural activity change evoked by acupuncture treatment for tinnitus. In this study, 17 chronic tinnitus patients and 22 age- and sex-matched normal subjects were recruited, and their tinnitus-related scales and hearing levels were collected. The fMRI data were measured before and after acupuncture, and then sliding-window and k-means clustering methods were used to calculate DFC and perform clustering analysis, respectively. We found that, compared with the normal subjects, chronic tinnitus patients had higher temporal variability of DFC between the supplementary motor area and medial part of the superior frontal gyrus, and it positively correlated with hearing loss. Clustering analysis showed higher transition probability (TP) between connection states in chronic tinnitus patients, and it was positively correlated with tinnitus severity. Furthermore, the findings showed that acupuncture treatment might improve tinnitus. DFC between the posterior cingulate gyrus and angular gyrus in chronic tinnitus patients after acupuncture showed significantly decreased, and it positively correlated with the improvement of tinnitus. Clustering analysis showed that acupuncture treatment might promote chronic tinnitus patients under lower DFC state, and it also positively correlated with the improvement of tinnitus. This study suggests that acupuncture as an alternative therapy method might decrease the tinnitus severity by decreasing the time variability of DFC in chronic tinnitus patients.

Impaired Inhibitory Control During Walking in Parkinson's Disease Patients: An EEG Study.

The performance on a visual Go/NoGo (VGNG) task during walking has been used to evaluate the effect of gait on response inhibition in young and older adults; however, no work has yet included Parkinson's disease (PD) patients for whom such changes may be even more enhanced. In this study, we aimed to explore the effect of gait on automatic and cognitive inhibitory control phases in PD patients and the associated changes in neural activity and compared them with young and older adults. 30 PD patients, 30 older adults, and 11 young adults performed a visual Go/NoGo task in a sitting position and during walking on a treadmill while their EEG activity and gait were recorded. Brain electrical activity was evaluated by the amplitude, latency, and scalp distribution of N2 and P300 event related potentials. Mix model analysis was used to examine group and condition effects on task performance and brain activity. The VGNG accuracy rates in PD patients during walking were lower than in young and older adults (F = 5.619, p = 0.006). For all groups, N2 latency during walking was significantly longer than during sitting (p = 0.013). In addition, P300 latency was significantly longer in PD patients (p < 0.001) and older adults (p = 0.032) during walking compared to sitting and during 'NoGo' trials compared with 'Go' trials. Moreover, the young adults showed the smallest number of electrodes for which a significant differential activation between sit to walk was observed, while PD patients showed the largest with N2 being more strongly manifested in bilateral parietal electrodes during walking and in frontocentral electrodes while seated. The results show that response inhibition during walking is impaired in older subjects and PD patients and that increased cognitive load during dual-task walking relates to significant change in scalp electrical activity, mainly in parietal and frontocentral channels.

Prefrontal cortical plasticity during learning of cognitive tasks

Training in working memory tasks is associated with lasting changes in prefrontal cortical activity. To assess the neural activity changes induced by training, we recorded single units, multi-unit activity (MUA) and local field potentials (LFP) with chronic electrode arrays implanted in the prefrontal cortex of two monkeys, throughout the period they were trained to perform cognitive tasks. Mastering different task phases was associated with distinct changes in neural activity, which included recruitment of larger numbers of neurons, increases or decreases of their firing rate, changes in the correlation structure between neurons, and redistribution of power across LFP frequency bands. In every training phase, changes induced by the actively learned task were also observed in a control task, which remained the same across the training period. Our results reveal how learning to perform cognitive tasks induces plasticity of prefrontal cortical activity, and how activity changes may generalize between tasks.

Focal neural perturbations reshape low-dimensional trajectories of brain activity supporting cognitive performance

The emergence of distributed patterns of neural activity supporting brain functions and behavior can be understood by study of the brain’s low-dimensional topology. Functional neuroimaging demonstrates that brain activity linked to adaptive behavior is constrained to low-dimensional manifolds. In human participants, we tested whether these low-dimensional constraints preserve working memory performance following local neuronal perturbations. We combined multi-session functional magnetic resonance imaging, non-invasive transcranial magnetic stimulation (TMS), and methods translated from the fields of complex systems and computational biology to assess the functional link between changes in local neural activity and the reshaping of task-related low dimensional trajectories of brain activity. We show that specific reconfigurations of low-dimensional trajectories of brain activity sustain effective working memory performance following TMS manipulation of local activity on, but not off, the space traversed by these trajectories. We highlight an association between the multi-scale changes in brain activity underpinning cognitive function.

Visual discrimination accuracy does not differ between nasal inhalation and exhalation when stimuli are voluntarily aligned to breathing phase

This study investigated the possible enhancement of visual discrimination accuracy by voluntarily adjusting the timing of stimulus presentation to a specific respiratory phase. Previous research has suggested that respiratory phases modulate perceptual and cognitive processing. For instance, a fearful face was identified faster when presented during nasal inhalation than during nasal exhalation, which could be related to changes in neural oscillatory activity synchronized with breathing in through one's nose. Based on such findings, the present study asked 40 young adults to perform an emotional discrimination task consisting of distinguishing fearful vs. neutral faces and a physical discrimination task consisting of distinguishing high- vs. low-contrast Gabor patches during nasal respiration. Participants presented themselves with the stimuli to be judged in a designated respiratory phase by pressing a button. It was hypothesized that fear discrimination accuracy would be higher during inhalation than exhalation if sensitivity to emotional stimuli increased during inhalation. Conversely, if overall visual sensitivity was enhanced during inhalation, the identical effect was expected for contrast discrimination. The results indicated that discrimination accuracy did not differ between inhalation and exhalation phases in either task. This result provided no evidence that the respiratory phase affected visual discrimination accuracy when people adjusted the timing of stimulus presentation to the onset of inhalation or exhalation.

Changes in pallidal neural activity following long-term symptom improvement from botulinum toxin treatment in DYT6 dystonia: a case report

BackgroundThe globus pallidus internus is the main target for the treatment of dystonia by deep brain stimulation. Unfortunately, for some genetic etiologies, the therapeutic outcome of dystonia is less predictable. In particular, therapeutic outcomes for deep brain stimulation in craniocervical and orolaryngeal dystonia in DYT6-positive patients are poor. Little is known about the neurophysiology of the globus pallidus internus in DYT6-positive dystonia, and how symptomatic treatment affects the neural activity of this region.Case presentationWe present here the case of a 55-year-old Caucasian female DYT6-dystonic patient with blepharospasm, spasmodic dysphonia, and oromandibular dystonia where single-unit and local field potential activity was recorded from the globus pallidus internus during two deep brain stimulation revision surgeries 4 years apart with no symptomatic improvement. Botulinum toxin injections consistently improved dysphonia, while some of the other symptoms were only inconsistently or marginally improved. Neural activity in the globus pallidus internus during both revision surgeries were compared with previously published results from an idiopathic dystonic cohort. Single-cell firing characteristics and local field potential from the first revision surgery showed no differences with our control group. However, during the second revision surgery, the mean firing rate of single units and local field potential power in the gamma range were lower than those present during the first revision surgery or the control group.ConclusionsSymptoms related to facial movements were greatly improved by botulinum toxin treatment between revision surgeries, which coincided with lower discharge rate and changes in gamma local field oscillations.

Neural indicator of positive reappraisal: A TMS-EEG study over the left VLPFC

BackgroundPositive reappraisal aims to reinterpret negative situations in a more positive light. Single-pulse transcranial magnetic stimulation (TMS) over the left ventrolateral prefrontal cortex (VLPFC) during positive reappraisal was suggested to improve emotion regulation capacity. However, it remains unclear whether the improvement of the capacity of emotion regulation was caused by the alterations of neural activity with TMS perturbation over the left VLPFC during positive reappraisal. MethodsSingle-pulse TMS was delivered among fifteen participants who engaged in positive reappraisal experiments with concurrent electroencephalogram (EEG) recordings. Participants repeated positive reappraisal experiments at three different stimulation settings: no stimulation, TMS pulses over the left VLPFC at 300 ms post-stimulus as the targeted stimulation and over the vertex as the control stimulation. ResultsTMS pulses over the left VLPFC at 300 ms post-stimuli increased late positive potential (LPP) amplitudes (300–800 ms) within the central-parietal and right prefrontal regions in response to the reappraisal stimuli compared with the negative stimuli. Moreover, changes in neural activity within the frontoparietal network contributed to the modulated LPP amplitudes of the reappraisal stimuli with the targeted stimulation. Importantly, the central-parietal LPP amplitudes of the reappraisal stimuli with the targeted stimulation was not only correlated with but also could predict the valence ratings using positive reappraisal. ConclusionOur study demonstrated a causal role of the left VLPFC in positive reappraisal, and provided a neural indicator to indicate the degree to which single-pulse TMS modulated the emotional experience using positive reappraisal. It shows promise to apply in future closed-loop neuromodulation.

Responses to antibiotics in human iPSC-derived neurons based on the clinical antibiotic-associated encephalopathy classification.

Antibiotic-associated encephalopathy (AAE) is a central nervous system disorder caused by antibiotics administration and classified into three types based on clinical symptoms. Type 1 AAE causes seizures and myoclonus, type 2 causes psychiatric symptoms, and type 3 is characterized by cerebellar ataxia. In this study, we investigated whether the electrical activity of in vitro human iPSC-derived neurons to antibiotics could be classified based on the 3 types of AAEs classified by clinical symptoms. Glutamatergic, GABAergic neurons and astrocytes differentiated from human iPS cells were seeded on micro-electrode array (MEA). The cumulative administration of 13 different antimicrobials detected changes in neural activity that differed according to AAE type. Next, we classified the antimicrobials by principal component analysis (PCA) and confirmed the AAE type of each agent. We found that Types 1-3 AAE agents were distributed separately. The classification of antibiotics depending on electrophysiological response characteristics was consistent with the clinical practice classification of AAEs. In conclusion, the combination of electrophysiological responses of human iPS cell-derived neural networks measured by MEA plus multivariate analysis methods will effectively detect and classify antibiotics developmental risks.

Changes of Resting-State Neural Activity and Nerve Fibers in Ischemic Stroke Patients with Hemiplegia

Changes of Resting-State Neural Activity and Nerve Fibers in Ischemic Stroke Patients with Hemiplegia

The abnormal fractional amplitude of low-frequency fluctuation changes in patients with diabetic optic neuropathy: a steady-state fMRI study.

The spontaneous changes in brain activity in patients with diabetic optic neuropathy using steady-state fMRI. The fractional amplitude of the low-frequency fluctuation method was applied to evaluate neural activity changes. The Hospital Anxiety and Depression Scale was used to assess the anxiety and depression status of participants. The independent sample t-test and chi-squared test were applied to analyze the demographics of diabetic optic neuropathy patients and healthy controls. Receiver operating characteristic curves were applied to analyze the variation in mean fractional amplitude of low-frequency fluctuation values between diabetic optic neuropathy patients and healthy controls. Pearson's correlation analysis analyzed the relationships between the fractional amplitude of low-frequency fluctuation values of brain regions and clinical behaviors in the diabetic optic neuropathy group. The fractional amplitude of low-frequency fluctuation value of diabetic optic neuropathy patients was significantly higher than healthy controls in the right precentral gyrus. However, the fractional amplitude of low-frequency fluctuation values in the right anterior cingulate gyrus and left middle cingulate gyrus were markedly decreased in diabetic optic neuropathy patients. The area under the curve of receiver operating characteristics for each brain region showed high accuracy. Pearson's correlation analysis showed that fractional amplitude of low-frequency fluctuation values of the right anterior cingulate gyrus and left middle cingulate gyrus was negatively correlated with Hospital Anxiety and Depression Scale scores. The fractional amplitude of low-frequency fluctuation values of the left middle cingulate gyrus was negatively correlated with diabetic optic neuropathy disease duration. In conclusion, we found abnormal spontaneous brain activities in regions related to cognitive and emotional dysfunction, eye movement disorder, and vision loss in patients with diabetic optic neuropathy. These results may indicate the underlying neuropathological mechanisms of diabetic optic neuropathy and show that fractional amplitude of low-frequency fluctuation may be an effective method to distinguish patients with diabetic optic neuropathy from healthy individuals.

The relationship between persistent organic pollutants and Attention Deficit Hyperactivity Disorder phenotypes: Evidence from task-based neural activity in an observational study of a community sample of Canadian mother-child dyads

BackgroundPrenatal exposure to persistent organic pollutants (POPs), widespread in North America, is associated with increased Attention Deficit/Hyperactivity Disorder (ADHD) symptoms and may be a modifiable risk for ADHD phenotypes. However, the effects of moderate exposure to POPs on task-based inhibitory control performance, related brain function, and ADHD-related symptoms remain unknown, limiting our ability to develop interventions targeting the neural impact of common levels of exposure. ObjectivesThe goal of this study was to examine the association between prenatal POP exposure and inhibitory control performance, neural correlates of inhibitory control and ADHD-related symptoms. MethodsProspective data was gathered in an observational study of Canadian mother-child dyads, with moderate exposure to POPs, including polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), as part of the GESTation and the Environment (GESTE) cohort in Sherbrooke, Quebec, Canada. The sample included 87 eligible children, 46 with maternal plasma samples, functional magnetic resonance imaging (fMRI) data of Simon task performance at 9–11 years, and parental report of clinical symptoms via the Behavioral Assessment System for Children 3 (BASC-3). Simon task performance was probed via drift diffusion modeling, and parameter estimates were related to POP exposure. Simon task-based fMRI data was modeled to examine the difference in incongruent vs congruent trials in regions of interest (ROIs) identified by meta analysis. ResultsOf the 46 participants with complete data, 29 were male, and mean age was 10.42 ± 0.55 years. Increased POP exposure was associated with reduced accuracy (e.g. PCB molar sum rate ratio = 0.95; 95% CI [0.90, 0.99]), drift rate (e.g. for PCB molar sum β = −0.42; 95% CI [-0.77, −0.07]), and task-related brain activity (e.g. in inferior frontal cortex for PCB molar sum β = −0.35; 95% CI [-0.69, −0.02]), and increased ADHD symptoms (e.g. hyperactivity PCB molar sum β = 2.35; 95%CI [0.17, 4.53]), supporting the possibility that prenatal exposure to POPs is a modifiable risk for ADHD phenotypes. DiscussionWe showed that exposure to POPs is related to task-based changes in neural activity in brain regions important for inhibitory control, suggesting a biological mechanism underlying previously documented associations between POPs and neurobehavioral deficits found in ADHD phenotypes.

Monitoring Brain State and Behavioral Performance during Repetitive Visual Stimulation

We tested whether changes in prestimulus neural activity predict behavioral performance (decision time and errors) during a prolonged visual task. The task was to classify ambiguous stimuli—Necker cubes; manipulating the degree of ambiguity from low ambiguity (LA) to high ambiguity (HA) changed the task difficulty. First, we assumed that the observer’s state changes over time, which leads to a change in the prestimulus brain activity. Second, we supposed that the prestimulus state produces a different effect on behavioral performance depending on the task demands. Monitoring behavioral responses, we revealed that the observer’s decision time decreased for both LA and HA stimuli during the task performance. The number of perceptual errors lowered for HA, but not for LA stimuli. EEG analysis revealed an increase in the prestimulus 9–11 Hz EEG power with task time. Finally, we found associations between the behavioral and neural estimates. The prestimulus EEG power negatively correlated with the decision time for LA stimuli and the erroneous responses rate for HA stimuli. The obtained results confirm that monitoring prestimulus EEG power enables predicting perceptual performance on the behavioral level. The observed different time-on-task effects on the LA and HA stimuli processing may shed light on the features of ambiguous perception.