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1.
Nat Commun ; 12(1): 3151, 2021 05 25.
Artigo em Inglês | MEDLINE | ID: mdl-34035240

RESUMO

Computational modeling and human studies suggest that transcranial alternating current stimulation (tACS) modulates alpha oscillations by entrainment. Yet, a direct examination of how tACS interacts with neuronal spiking activity that gives rise to the alpha oscillation in the thalamo-cortical system has been lacking. Here, we demonstrate how tACS entrains endogenous alpha oscillations in head-fixed awake ferrets. We first show that endogenous alpha oscillations in the posterior parietal cortex drive the primary visual cortex and the higher-order visual thalamus. Spike-field coherence is largest for the alpha frequency band, and presumed fast-spiking inhibitory interneurons exhibit strongest coupling to this oscillation. We then apply alpha-tACS that results in a field strength comparable to what is commonly used in humans (<0.5 mV/mm). Both in these ferret experiments and in a computational model of the thalamo-cortical system, tACS entrains alpha oscillations by following the theoretically predicted Arnold tongue. Intriguingly, the fast-spiking inhibitory interneurons exhibit a stronger entrainment response to tACS in both the ferret experiments and the computational model, likely due to their stronger endogenous coupling to the alpha oscillation. Our findings demonstrate the in vivo mechanism of action for the modulation of the alpha oscillation by tACS.


Assuntos
Ritmo alfa/fisiologia , Tálamo/fisiologia , Estimulação Transcraniana por Corrente Contínua/métodos , Córtex Visual/fisiologia , Animais , Simulação por Computador , Eletrodos Implantados , Eletroencefalografia , Feminino , Furões , Interneurônios/fisiologia , Imageamento por Ressonância Magnética , Masculino , Microeletrodos , Modelos Animais , Modelos Neurológicos , Rede Nervosa/fisiologia , Optogenética , Tálamo/citologia , Tálamo/diagnóstico por imagem , Tomografia Computadorizada por Raios X , Estimulação Transcraniana por Corrente Contínua/instrumentação , Córtex Visual/citologia , Córtex Visual/diagnóstico por imagem
2.
PLoS One ; 16(1): e0242830, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33411746

RESUMO

Although investigation of the brains of criminals began quite early in the history of psychophysiological research, little is known about brain plasticity of offenders with psychopathy. Building on our preliminary study reporting successful brain self-regulation using slow cortical potential (SCP) neurofeedback in offenders with psychopathy, we investigated the central nervous and autonomic peripheral changes occurring after brain self-regulation in a group of severe male offenders with psychopathy. Regarding the central nervous system, an overall suppression of the psychopathic overrepresentation of slow frequency bands was found, such as delta and theta band activity, after EEG neurofeedback. In addition, an increase in alpha band activity could be observed after the SCP self-regulation training. Electrodermal activity adaptively changed according to the regulation task, and this flexibility improved over training time. The results of this study point towards a constructive learning process and plasticity in neural and peripheral measures of offenders with psychopathy.


Assuntos
Transtorno da Personalidade Antissocial/diagnóstico por imagem , Transtorno da Personalidade Antissocial/psicologia , Encéfalo/diagnóstico por imagem , Criminosos/psicologia , Eletroencefalografia , Resposta Galvânica da Pele , Autocontrole , Potenciais de Ação , Adulto , Ritmo alfa/fisiologia , Análise de Variância , Transtorno da Personalidade Antissocial/fisiopatologia , Encéfalo/fisiopatologia , Humanos , Masculino , Neurorretroalimentação , Projetos Piloto , Descanso , Análise e Desempenho de Tarefas
3.
Int J Neural Syst ; 30(6): 2050026, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32498642

RESUMO

Brain-computer interfaces (BCIs) can provide a means of communication to individuals with severe motor disorders, such as those presenting as locked-in. Many BCI paradigms rely on motor neural pathways, which are often impaired in these individuals. However, recent findings suggest that visuospatial function may remain intact. This study aimed to determine whether visuospatial imagery, a previously unexplored task, could be used to signify intent in an online electroencephalography (EEG)-based BCI. Eighteen typically developed participants imagined checkerboard arrow stimuli in four quadrants of the visual field in 5-s trials, while signals were collected using 16 dry electrodes over the visual cortex. In online blocks, participants received graded visual feedback based on their performance. An initial BCI pipeline (visuospatial imagery classifier I) attained a mean accuracy of [Formula: see text]% classifying rest against visuospatial imagery in online trials. This BCI pipeline was further improved using restriction to alpha band features (visuospatial imagery classifier II), resulting in a mean pseudo-online accuracy of [Formula: see text]%. Accuracies exceeded the threshold for practical BCIs in 12 participants. This study supports the use of visuospatial imagery as a real-time, binary EEG-BCI control paradigm.


Assuntos
Interfaces Cérebro-Computador , Eletroencefalografia , Retroalimentação Sensorial/fisiologia , Imaginação/fisiologia , Intenção , Reconhecimento Visual de Modelos/fisiologia , Percepção Espacial/fisiologia , Córtex Visual/fisiologia , Adulto , Ritmo alfa/fisiologia , Humanos
4.
J Neurosci ; 40(25): 4913-4924, 2020 06 17.
Artigo em Inglês | MEDLINE | ID: mdl-32404346

RESUMO

Attentional selection mechanisms in visual cortex involve changes in oscillatory activity in the EEG alpha band (8-12 Hz), with decreased alpha indicating focal cortical enhancement and increased alpha indicating suppression. This has been observed for spatial selective attention and attention to stimulus features such as color versus motion. We investigated whether attention to objects involves similar alpha-mediated changes in focal cortical excitability. In experiment 1, 20 volunteers (8 males; 12 females) were cued (80% predictive) on a trial-by-trial basis to different objects (faces, scenes, or tools). Support vector machine decoding of alpha power patterns revealed that late (>500 ms latency) in the cue-to-target foreperiod, only EEG alpha differed with the to-be-attended object category. In experiment 2, to eliminate the possibility that decoding of the physical features of cues led to our results, 25 participants (9 males; 16 females) performed a similar task where cues were nonpredictive of the object category. Alpha decoding was now only significant in the early (<200 ms) foreperiod. In experiment 3, to eliminate the possibility that task set differences between the different object categories led to our experiment 1 results, 12 participants (5 males; 7 females) performed a predictive cuing task where the discrimination task for different objects was identical across object categories. The results replicated experiment 1. Together, these findings support the hypothesis that the neural mechanisms of visual selective attention involve focal cortical changes in alpha power not only for simple spatial and feature attention, but also for high-level object attention in humans.SIGNIFICANCE STATEMENT Attention is the cognitive function that enables relevant information to be selected from sensory inputs so it can be processed in the support of goal-directed behavior. Visual attention is widely studied, yet the neural mechanisms underlying the selection of visual information remain unclear. Oscillatory EEG activity in the alpha range (8-12 Hz) of neural populations receptive to target visual stimuli may be part of the mechanism, because alpha is thought to reflect focal neural excitability. Here, we show that alpha-band activity, as measured by scalp EEG from human participants, varies with the specific category of object selected by attention. This finding supports the hypothesis that alpha-band activity is a fundamental component of the neural mechanisms of attention.


Assuntos
Ritmo alfa/fisiologia , Atenção/fisiologia , Córtex Visual/fisiologia , Adulto , Antecipação Psicológica/fisiologia , Feminino , Humanos , Masculino , Máquina de Vetores de Suporte , Percepção Visual/fisiologia
5.
PLoS One ; 15(4): e0231698, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32324752

RESUMO

Thermosensation is crucial for humans to probe the environment and detect threats arising from noxious heat or cold. Over the last years, EEG frequency-tagging using long-lasting periodic radiant heat stimulation has been proposed as a means to study the cortical processes underlying tonic heat perception. This approach is based on the notion that periodic modulation of a sustained stimulus can elicit synchronized periodic activity in the neuronal populations responding to the stimulus, known as a steady-state response (SSR). In this paper, we extend this approach using a contact thermode to generate both heat- and cold-evoked SSRs. Furthermore, we characterize the temporal dynamics of the elicited responses, relate these dynamics to perception, and assess the effects of displacing the stimulated skin surface to gain insight on the heat- and cold-sensitive afferents conveying these responses. Two experiments were conducted in healthy volunteers. In both experiments, noxious heat and innocuous cool stimuli were applied during 75 seconds to the forearm using a Peltier-based contact thermode, with intensities varying sinusoidally at 0.2 Hz. Displacement of the thermal stimulation on the skin surface was achieved by independently controlling the Peltier elements of the thermal probe. Continuous intensity ratings to sustained heat and cold stimulation were obtained in the first experiment with 14 subjects, and the EEG was recorded in the second experiment on 15 subjects. Both contact heat and cool stimulation elicited periodic EEG responses and percepts. Compared to heat stimulation, the responses to cool stimulation had a lower magnitude and shorter latency. All responses tended to habituate along time, and this response attenuation was most pronounced for cool compared to warm stimulation, and for stimulation delivered using a fixed surface compared to a variable surface.


Assuntos
Temperatura Baixa , Eletroencefalografia , Temperatura Alta , Percepção , Processamento de Sinais Assistido por Computador , Sensação Térmica/fisiologia , Adulto , Ritmo alfa/fisiologia , Análise de Variância , Feminino , Habituação Psicofisiológica , Humanos , Masculino , Fatores de Tempo , Adulto Jovem
6.
Sci Rep ; 10(1): 6744, 2020 04 21.
Artigo em Inglês | MEDLINE | ID: mdl-32317774

RESUMO

Non-pharmacological treatment (NPT) improves cognitive functions and behavioural disturbances in patients with dementia, but the underlying neural mechanisms are unclear. In this observational study, 21 patients with dementia received NPTs for several months. Patients were scanned using magnetoencephalography twice during the NPT period to evaluate NPT effects on resting-state brain activity. Additionally, cognitive functions and behavioural disturbances were measured using the Mini-Mental State Examination (MMSE-J) and a short version of the Dementia Behaviour Disturbance Scale (DBD-13) at the beginning and the end of the NPT period. In contrast to the average DBD-13 score, the average MMSE-J score improved after the NPT period. Magnetoencephalography data revealed a reduced alpha activity in the right temporal lobe and fusiform gyrus, as well as an increased low-gamma activity in the right angular gyrus. DBD-13 score changes were correlated with beta activity in the sensorimotor area. These findings corroborate previous studies confirming NPT effects on brain activity in healthy participants and people at risk of dementia. Our results provide additional evidence that brains of patients with dementia have the capacity for plasticity, which may be responsible for the observed NPT effects. In dementia, NPT might lead to improvements in the quality of life.


Assuntos
Doença de Alzheimer/terapia , Terapia Cognitivo-Comportamental/métodos , Demência Vascular/terapia , Horticultura Terapêutica/métodos , Lobo Parietal/fisiopatologia , Lobo Temporal/fisiopatologia , Idoso , Idoso de 80 Anos ou mais , Ritmo alfa/fisiologia , Doença de Alzheimer/diagnóstico por imagem , Doença de Alzheimer/fisiopatologia , Ritmo beta/fisiologia , Cognição/fisiologia , Demência Vascular/diagnóstico por imagem , Demência Vascular/fisiopatologia , Exercício Físico/psicologia , Feminino , Ritmo Gama/fisiologia , Humanos , Magnetoencefalografia , Masculino , Testes de Estado Mental e Demência , Cuidados de Enfermagem/métodos , Lobo Parietal/diagnóstico por imagem , Qualidade de Vida/psicologia , Desempenho de Papéis , Lobo Temporal/diagnóstico por imagem
7.
J Neurosci ; 40(20): 4010-4020, 2020 05 13.
Artigo em Inglês | MEDLINE | ID: mdl-32284338

RESUMO

Probabilistic associations between stimuli afford memory templates that guide perception through proactive anticipatory mechanisms. A great deal of work has examined the behavioral consequences and human electrophysiological substrates of anticipation following probabilistic memory cues that carry spatial or temporal information to guide perception. However, less is understood about the electrophysiological substrates linked to anticipating the sensory content of events based on recurring associations between successive events. Here, we demonstrate behavioral and electrophysiological signatures of using associative-memory templates to guide perception, while equating spatial and temporal anticipation (experiments 1 and 2), as well as target probability and response demands (experiment 2). By recording the electroencephalogram in the two experiments (N = 55; 24 females), we show that two markers in human electrophysiology implicated in spatial and temporal anticipation also contribute to the anticipation of perceptual identity, as follows: attenuation of alpha-band oscillations and the contingent negative variation (CNV). Together, our results show that memory-guided identity templates proactively impact perception and are associated with anticipatory states of attenuated alpha oscillations and the CNV. Furthermore, by isolating object-identity anticipation from spatial and temporal anticipation, our results suggest a role for alpha attenuation and the CNV in specific visual content anticipation beyond general changes in neural excitability or readiness.SIGNIFICANCE STATEMENT Probabilistic associations between stimuli afford memory templates that guide perception through proactive anticipatory mechanisms. The current work isolates the behavioral benefits and electrophysiological signatures of memory-guided identity-based anticipation, while equating anticipation of space, time, motor responses, and task relevance. Our results show that anticipation of the specific identity of a forthcoming percept impacts performance and is associated with states of attenuated alpha oscillations and the contingent negative variation, extending previous work implicating these neural substrates in spatial and temporal preparatory attention. Together, this work bridges fields of attention, memory, and perception, providing new insights into the neural mechanisms that support complex attentional templates.


Assuntos
Antecipação Psicológica/fisiologia , Aprendizagem por Associação/fisiologia , Memória/fisiologia , Percepção Visual/fisiologia , Adulto , Ritmo alfa/fisiologia , Sinais (Psicologia) , Eletroencefalografia , Fenômenos Eletrofisiológicos/fisiologia , Feminino , Humanos , Masculino , Desempenho Psicomotor/fisiologia , Percepção Espacial/fisiologia , Adulto Jovem
8.
Sci Rep ; 10(1): 4228, 2020 03 06.
Artigo em Inglês | MEDLINE | ID: mdl-32144318

RESUMO

The role of resting frontal alpha-asymmetry in explaining neural-mechanisms of affect and approach/withdrawal behavior is still debatable. The present study explores the ability of the quasi-stable resting EEG asymmetry information and the associated neurovascular synchronization/desynchronization in bringing more insight into the understanding of neural-mechanisms of affect and approach/withdrawal behavior. For this purpose, a novel frontal alpha-asymmetry based on microstates, that assess quasi-stable EEG scalp topography information, is proposed and compared against standard frontal-asymmetry. Both proposed and standard frontal alpha-asymmetries were estimated from thirty-nine healthy volunteers resting-EEG simultaneously acquired with resting-fMRI. Further, neurovascular mechanisms of these asymmetry measures were estimated through EEG-informed fMRI. Subsequently, the Hemodynamic Lateralization Index (HLI) of the neural-underpinnings of both asymmetry measures was assessed. Finally, the robust correlation of both asymmetry-measures and their HLI's with PANAS, BIS/BAS was carried out. The standard resting frontal-asymmetry and its HLI yielded no significant correlation with any psychological-measures. However, the microstate resting frontal-asymmetry correlated significantly with negative affect and its neural underpinning's HLI significantly correlated with Positive/Negative affect and BIS/BAS measures. Finally, alpha-BOLD desynchronization was observed in neural-underpinning whose HLI correlated significantly with negative affect and BIS. Hence, the proposed resting microstate-frontal asymmetry better assesses the neural-mechanisms of affect, approach/withdrawal behavior.


Assuntos
Potenciais de Ação , Ritmo alfa/fisiologia , Encéfalo/fisiologia , Comportamento de Escolha/fisiologia , Rede Nervosa/fisiologia , Comportamento Problema/psicologia , Descanso/fisiologia , Adolescente , Adulto , Mapeamento Encefálico , Eletroencefalografia , Humanos , Imageamento por Ressonância Magnética , Masculino , Adulto Jovem
9.
J Neurosci ; 40(17): 3443-3454, 2020 04 22.
Artigo em Inglês | MEDLINE | ID: mdl-32179571

RESUMO

Biases in sensory perception can arise from both experimental manipulations and personal trait-like features. These idiosyncratic biases and their neural underpinnings are often overlooked in studies on the physiology underlying perception. A potential candidate mechanism reflecting such idiosyncratic biases could be spontaneous alpha band activity, a prominent brain rhythm known to influence perceptual reports in general. Using a temporal order judgment task, we here tested the hypothesis that alpha power reflects the overcoming of an idiosyncratic bias. Importantly, to understand the interplay between idiosyncratic biases and contextual (temporary) biases induced by experimental manipulations, we quantified this relation before and after temporal recalibration. Using EEG recordings in human participants (male and female), we find that prestimulus frontal alpha power correlates with the tendency to respond relative to an own idiosyncratic bias, with stronger α leading to responses matching the bias. In contrast, alpha power does not predict response correctness. These results also hold after temporal recalibration and are specific to the alpha band, suggesting that alpha band activity reflects, directly or indirectly, processes that help to overcome an individual's momentary bias in perception. We propose that combined with established roles of parietal α in the encoding of sensory information frontal α reflects complementary mechanisms influencing perceptual decisions.SIGNIFICANCE STATEMENT The brain is a biased organ, frequently generating systematically distorted percepts of the world, leading each of us to evolve in our own subjective reality. However, such biases are often overlooked or considered noise when studying the neural mechanisms underlying perception. We show that spontaneous alpha band activity predicts the degree of biasedness of human choices in a time perception task, suggesting that alpha activity indexes processes needed to overcome an individual's idiosyncratic bias. This result provides a window onto the neural underpinnings of subjective perception, and offers the possibility to quantify or manipulate such priors in future studies.


Assuntos
Ritmo alfa/fisiologia , Percepção Auditiva/fisiologia , Encéfalo/fisiologia , Percepção do Tempo/fisiologia , Percepção Visual/fisiologia , Adulto , Eletroencefalografia , Feminino , Humanos , Individualidade , Masculino , Adulto Jovem
10.
PLoS One ; 15(3): e0229334, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32163441

RESUMO

Attention operates through top-down (TD) and bottom-up (BU) mechanisms. Recently, it has been shown that slow (alpha) frequencies index facilitatory and suppressive mechanisms of TD attention and faster (gamma) frequencies signal BU attentional capture. Ageing is characterized by increased behavioral distractibility, resulting from either a reduced efficiency of TD attention or an enhanced triggering of BU attention. However, only few studies have investigated the impact of ageing upon the oscillatory activities involved in TD and BU attention. MEG data were collected from 14 elderly and 14 matched young healthy human participants while performing the Competitive Attention Task. Elderly participants displayed (1) exacerbated behavioral distractibility, (2) altered TD suppressive mechanisms, indexed by a reduced alpha synchronization in task-irrelevant regions, (3) less prominent alpha peak-frequency differences between cortical regions, (4) a similar BU system activation indexed by gamma activity, and (5) a reduced activation of lateral prefrontal inhibitory control regions. These results show that the ageing-related increased distractibility is of TD origin.


Assuntos
Envelhecimento/fisiologia , Ritmo alfa/fisiologia , Antecipação Psicológica/fisiologia , Atenção/fisiologia , Encéfalo/fisiologia , Ritmo Gama/fisiologia , Tempo de Reação/fisiologia , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estimulação Luminosa , Adulto Jovem
11.
PLoS One ; 15(3): e0229950, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32163454

RESUMO

A decrease in alpha band power is defined as a hallmark of electroencephalogram (EEG) in Alzheimer's disease (AD). This study devotes to understanding the neuronal correlates of alpha rhythm slowing associated with AD from the view of neurocomputation. Firstly, a modified computational model of thalamo-cortico-thalamic (TCT) circuitry is constructed by incorporating two important biologically plausible ingredients. One is the disinhibition property between different inhibitory interneurons in the cortical module. The other is the full relay function of thalamic relay nucleus (TCR) to the cortical module. Then, by decreasing synaptic connectivity parameters to mimic the neuropathological condition of synapse loss in AD, the correlation between neuronal synaptic behavior and abnormal alpha rhythm is simulated by means of power spectral analysis. The results indicate that these decreases of synaptic activity, i.e., not only the excitatory synaptic connections from TCR to fast inhibitory interneurons Cfte and from excitatory interneurons to pyramidal neurons Cpxe but also the inhibitory synaptic connections from fast inhibitory interneurons to slow inhibitory interneurons Clfi and from inhibitory interneurons to TCR Ctii, can significantly diminish the peak power density over the alpha band of the thalamic output, which implies that there is a slowing of alpha band. Furthermore, the underlying mechanism behind the alpha rhythmic changes is analyzed using nonlinear dynamical technique. The results reveal that decreases of Cfte, Cpxe, Clfi and Ctii can make the thalamic module transfer from a limit cycle mode to a point attractor mode, which may lead to the alpha rhythm slowing in the modified TCT model. We expect this work can be helpful in identifying early biomarkers of AD's EEG and understanding potential pathogenesis of AD.


Assuntos
Ritmo alfa/fisiologia , Doença de Alzheimer/fisiopatologia , Córtex Cerebral/fisiopatologia , Modelos Biológicos , Núcleos Talâmicos/fisiopatologia , Doença de Alzheimer/diagnóstico , Simulação por Computador , Humanos , Interneurônios/fisiologia , Vias Neurais/fisiopatologia , Dinâmica não Linear , Sinapses/fisiologia
12.
Sci Rep ; 10(1): 5419, 2020 03 25.
Artigo em Inglês | MEDLINE | ID: mdl-32214173

RESUMO

Neural activity is known to oscillate within discrete frequency bands and the synchronization between these rhythms is hypothesized to underlie information integration in the brain. Since strict synchronization is only possible for harmonic frequencies, a recent theory proposes that the interaction between different brain rhythms is facilitated by transient harmonic frequency arrangements. In this line, it has been recently shown that the transient occurrence of 2:1 harmonic cross-frequency relationships between alpha and theta rhythms (i.e. falpha ≈ 12 Hz; ftheta ≈ 6 Hz) is enhanced during effortful cognition. In this study, we tested whether achieving a state of 'mental emptiness' during meditation is accompanied by a relative decrease in the occurrence of 2:1 harmonic cross-frequency relationships between alpha and theta rhythms. Continuous EEG recordings (19 electrodes) were obtained from 43 highly experienced meditators during meditation practice, rest and an arithmetic task. We show that the occurrence of transient alpha:theta 2:1 harmonic relationships increased linearly from a meditative to an active cognitive processing state (i.e. meditation < rest < arithmetic task). It is argued that transient EEG cross-frequency arrangements that prevent alpha:theta cross-frequency coupling could facilitate the experience of 'mental emptiness' by avoiding the interaction between the memory and executive components of cognition.


Assuntos
Ritmo alfa/fisiologia , Conscientização/fisiologia , Cognição/fisiologia , Meditação/psicologia , Descanso/fisiologia , Ritmo Teta/fisiologia , Adulto , Encéfalo , Eletroencefalografia/métodos , Feminino , Humanos , Masculino , Matemática/métodos , Pessoa de Meia-Idade
13.
Nat Commun ; 11(1): 925, 2020 02 17.
Artigo em Inglês | MEDLINE | ID: mdl-32066740

RESUMO

Recent studies suggest that attention samples space rhythmically through oscillatory interactions in the frontoparietal network. How these attentional fluctuations coincide with spatial exploration/displacement and exploitation/selection by a dynamic attentional spotlight under top-down control is unclear. Here, we show a direct contribution of prefrontal attention selection mechanisms to a continuous space exploration. Specifically, we provide a direct high spatio-temporal resolution prefrontal population decoding of the covert attentional spotlight. We show that it continuously explores space at a 7-12 Hz rhythm. Sensory encoding and behavioral reports are increased at a specific optimal phase w/ to this rhythm. We propose that this prefrontal neuronal rhythm reflects an alpha-clocked sampling of the visual environment in the absence of eye movements. These attentional explorations are highly flexible, how they spatially unfold depending both on within-trial and across-task contingencies. These results are discussed in the context of exploration-exploitation strategies and prefrontal top-down attentional control.


Assuntos
Atenção/fisiologia , Modelos Neurológicos , Córtex Pré-Frontal/fisiologia , Movimentos Sacádicos/fisiologia , Percepção Espacial/fisiologia , Ritmo alfa/fisiologia , Animais , Técnicas de Observação do Comportamento , Comportamento Animal/fisiologia , Sinais (Psicologia) , Haplorrinos , Cadeias de Markov , Estimulação Luminosa , Análise Espaço-Temporal
14.
J Neurosci ; 40(11): 2343-2356, 2020 03 11.
Artigo em Inglês | MEDLINE | ID: mdl-32019830

RESUMO

Goal-directed behavior can benefit from proactive adjustments of cognitive control that occur in anticipation of forthcoming cognitive control demands (CCD). Predictions of forthcoming CCD are thought to depend on learning and memory in two ways: First, through direct experience, associative encoding may link previously experienced CCD to its triggering item, such that subsequent encounters with the item serve to cue retrieval of (i.e., predict) the associated CCD. Second, in the absence of direct experience, pattern completion and mnemonic integration mechanisms may allow CCD to be generalized from its associated item to other items related in memory. While extant behavioral evidence documents both types of CCD prediction, the neurocognitive mechanisms giving rise to these predictions remain largely unexplored. Here, we tested two hypotheses: (1) memory-guided predictions about CCD precede control adjustments due to the actual CCD required; and (2) generalization of CCD can be accomplished through integration mechanisms that link partially overlapping CCD-item and item-item associations in memory. Supporting these hypotheses, the temporal dynamics of theta and alpha power in human electroencephalography data (n = 43, 26 females) revealed that an associative CCD effect emerges earlier than interaction effects involving actual CCD. Furthermore, generalization of CCD from one item (X) to another item (Y) was predicted by a decrease in alpha power following the presentation of the X-Y pair. These findings advance understanding of the mechanisms underlying memory-guided adjustments of cognitive control.SIGNIFICANCE STATEMENT Cognitive control adaptively regulates information processing to align with task goals. Experience-based expectations enable adjustments of control, leading to improved performance when expectations match the actual control demand required. Using EEG, we demonstrate that memory for past cognitive control demand proactively guides the allocation of cognitive control, preceding adjustments of control triggered by the demands of the present environment. Furthermore, we demonstrate that learned cognitive control demands can be generalized through mnemonic integration processes, enabling the spread of expectations about cognitive control demands to items associated in memory. We reveal that this generalization is linked to decreased alpha oscillation in medial frontal channels. Collectively, these findings provide new insights into how memory-control interactions facilitate goal-directed behavior.


Assuntos
Aprendizagem por Associação/fisiologia , Cognição/fisiologia , Memória/fisiologia , Adaptação Psicológica , Adolescente , Adulto , Ritmo alfa/fisiologia , Mapeamento Encefálico , Sinais (Psicologia) , Eletroencefalografia , Feminino , Objetivos , Humanos , Masculino , Desempenho Psicomotor/fisiologia , Tempo de Reação , Teste de Stroop , Ritmo Teta/fisiologia , Fatores de Tempo , Adulto Jovem
15.
J Neurosci ; 40(12): 2510-2518, 2020 03 18.
Artigo em Inglês | MEDLINE | ID: mdl-32034067

RESUMO

Memories for past experiences can range from vague recognition to full-blown recall of associated details. Electroencephalography has shown that recall signals unfold a few hundred milliseconds after simple recognition, but has only provided limited insights into the underlying brain networks. Functional magnetic resonance imaging (fMRI) has revealed a "core recollection network" (CRN) centered on posterior parietal and medial temporal lobe regions, but the temporal dynamics of these regions during retrieval remain largely unknown. Here we used Magnetoencephalography in a memory paradigm assessing correct rejection (CR) of lures, item recognition (IR) and associative recall (AR) in human participants of both sexes. We found that power decreases in the alpha frequency band (10-12 Hz) systematically track different mnemonic outcomes in both time and space: Over left posterior sensors, alpha power decreased in a stepwise fashion from 500 ms onward, first from CR to IR and then from IR to AR. When projecting alpha power into source space, the CRN known from fMRI studies emerged, including posterior parietal cortex (PPC) and hippocampus. While PPC showed a monotonic change across conditions, hippocampal effects were specific to recall. These region-specific effects were corroborated by a separate fMRI dataset. Importantly, alpha power time courses revealed a temporal dissociation between item and associative memory in hippocampus and PPC, with earlier AR effects in hippocampus. Our data thus link engagement of the CRN to the temporal dynamics of episodic memory and highlight the role of alpha rhythms in revealing when and where different types of memories are retrieved.SIGNIFICANCE STATEMENT Our ability to remember ranges from the vague feeling of familiarity to vivid recollection of associated details. Scientific understanding of episodic memory thus far relied upon separate lines of research focusing on either temporal (via electroencephalography) or spatial (via functional magnetic resonance imaging) dimensions. However, both techniques have limitations that have hindered understanding of when and where memories are retrieved. Capitalizing on the enhanced temporal and spatial resolution of magnetoencephalography, we show that changes in alpha power reveal both when and where different types of memory are retrieved. Having access to the temporal and spatial characteristics of successful retrieval provided new insights into the cross-regional dynamics in the hippocampus and parietal cortex.


Assuntos
Ritmo alfa/fisiologia , Aprendizagem por Associação/fisiologia , Rememoração Mental/fisiologia , Adolescente , Adulto , Mapeamento Encefálico , Feminino , Hipocampo/fisiologia , Humanos , Magnetoencefalografia , Masculino , Rede Nervosa/diagnóstico por imagem , Rede Nervosa/fisiologia , Lobo Parietal/fisiologia , Desempenho Psicomotor/fisiologia , Reconhecimento Psicológico , Adulto Jovem
16.
Brain Cogn ; 138: 105508, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31838302

RESUMO

To determine the neuroelectric underpinnings of exercise-induced changes in working memory, this study investigated the acute effects ofaerobic exercise (AE) on the P3 component of an event-related potential and brain oscillations during a serial n-back task. Task-related electroencephalography was collected in 23 young adults following 20 min of rest and AE on separate, counterbalanced days. The results revealed reductions in standard deviation of response time and coefficient of variation of response time following AE compared to rest. Neuroelectric analyses showed increased P3 amplitude following AE compared to rest. Task-related frontal alpha desynchronization was stronger in the 2-back compared with the 1-back task following AE, while no such modulation was observed following rest. These findings suggest AE may temporarily enhance working memory, as reflected by decreases in response variability, which are accompanied by neuroelectric indices reflecting greater upregulation of attentional processes.


Assuntos
Ritmo alfa/fisiologia , Atenção/fisiologia , Sincronização Cortical/fisiologia , Potencial Evocado P300/fisiologia , Exercício Físico/fisiologia , Memória de Curto Prazo/fisiologia , Desempenho Psicomotor/fisiologia , Tempo de Reação/fisiologia , Ritmo Teta/fisiologia , Adulto , Feminino , Humanos , Masculino , Adulto Jovem
17.
Clin Neurophysiol ; 131(1): 205-212, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31812081

RESUMO

OBJECTIVE: Global EEG alpha activity is negatively correlated with skin conductance level (SCL), supporting alpha as an inverse marker of arousal. Frequency Principal Components Analysis (f-PCA) of resting EEG amplitude spectra has demonstrated natural components in the alpha band of healthy persons. This is a preliminary exploration of whether such components differ with arousal, possibly underpinning the anomalous ADHD hypoarousal link to reduced alpha. METHOD: Twenty-seven right-handed undergraduate students participated in three 2 minute blocks of resting eyes-open/closed EEG and SCL: EO1, EC, EO2. For each condition, mean EEG spectra were submitted to separate f-PCAs. RESULTS: The inverse alpha/SCL relationship was confirmed for band amplitudes. EO had two alpha components; both correlated negatively with SCL. EC alpha contained four components, but only one had a substantial negative correlation with SCL; two had no relationship, suggesting natural alpha components with different non-arousal functionality in EC. CONCLUSION: Some alpha components in both EC and EO reflect arousal, with other non-arousal components in EC. Our f-PCA approach offers insight into previously-noted alpha anomalies in disorders such as ADHD. SIGNIFICANCE: This proof of concept demonstration in typical participants may provide the basis for a new research effort in clinical disorders involving atypical arousal patterns.


Assuntos
Ritmo alfa/fisiologia , Nível de Alerta/fisiologia , Eletroencefalografia/métodos , Resposta Galvânica da Pele/fisiologia , Descanso/fisiologia , Adulto , Transtorno do Deficit de Atenção com Hiperatividade/fisiopatologia , Feminino , Voluntários Saudáveis , Humanos , Masculino , Estudo de Prova de Conceito , Adulto Jovem
18.
Neuron ; 105(3): 577-587.e5, 2020 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-31812515

RESUMO

Decreases in alpha synchronization are correlated with enhanced attention, whereas alpha increases are correlated with inattention. However, correlation is not causality, and synchronization may be a byproduct of attention rather than a cause. To test for a causal role of alpha synchrony in attention, we used MEG neurofeedback to train subjects to manipulate the ratio of alpha power over the left versus right parietal cortex. We found that a comparable alpha asymmetry developed over the visual cortex. The alpha training led to corresponding asymmetrical changes in visually evoked responses to probes presented in the two hemifields during training. Thus, reduced alpha was associated with enhanced sensory processing. Testing after training showed a persistent bias in attention in the expected directions. The results support the proposal that alpha synchrony plays a causal role in modulating attention and visual processing, and alpha training could be used for testing hypotheses about synchrony.


Assuntos
Ritmo alfa/fisiologia , Atenção/fisiologia , Neurorretroalimentação/métodos , Neurorretroalimentação/fisiologia , Percepção Espacial/fisiologia , Adulto , Feminino , Humanos , Magnetoencefalografia/métodos , Masculino , Estimulação Luminosa/métodos , Adulto Jovem
19.
Clin Neurophysiol ; 131(1): 330-342, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31506235

RESUMO

OBJECTIVE: Altered brain functional connectivity has been shown in youth with attention-deficit/hyperactivity disorder (ADHD). However, relatively little is known about functional connectivity in adult ADHD, and how it is linked with the heritability of ADHD. METHODS: We measured eyes-open and eyes-closed resting electroencephalography (EEG) from 38 adults with ADHD, 45 1st degree relatives of people with ADHD and 51 healthy controls. Functional connectivity among all scalp channels was calculated using a weighted phase lag index for delta, theta, alpha, beta and gamma frequency bands. A machine learning analysis using penalized linear regression was used to identify if connectivity features (10,080 connectivity pairs) could predict ADHD symptoms. Furthermore, we examined if EEG connectivity could accurately classify participants into ADHD, 1st degree relatives and/or control groups. RESULTS: Hyperactive symptoms were best predicted by eyes-open EEG connectivity in delta, beta and gamma bands. Inattentive symptoms were predicted by eyes-open EEG connectivity in delta, alpha and gamma bands, and eyes-closed EEG connectivity in delta and gamma bands. EEG connectivity features did not reliably classify participants into groups. CONCLUSIONS: EEG connectivity may represent a neuromarker for ADHD symptoms. SIGNIFICANCE: EEG connectivity may help elucidate the neural basis of adult ADHD symptoms.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/fisiopatologia , Conectoma , Eletroencefalografia/métodos , Adulto , Ritmo alfa/fisiologia , Transtorno do Deficit de Atenção com Hiperatividade/diagnóstico , Ritmo beta/fisiologia , Estudos de Casos e Controles , Ritmo Delta/fisiologia , Feminino , Ritmo Gama/fisiologia , Humanos , Modelos Lineares , Aprendizado de Máquina , Masculino , Pais , Transtornos da Percepção/fisiopatologia , Agitação Psicomotora/fisiopatologia , Irmãos , Avaliação de Sintomas , Ritmo Teta/fisiologia
20.
Eur Arch Psychiatry Clin Neurosci ; 270(2): 217-227, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30552507

RESUMO

Major depressive disorder (MDD), characterized by low mood or anhedonia, is commonly associated with a greater suicidal susceptibility. There are numerous suicide-related findings pertaining to the dorsolateral prefrontal cortex (DLPFC), caudate nucleus and thalamus, which form a cortico-striato-thalamo-cortical (CSTC) circuit responsible for executive function and working memory. An aberrant CSTC circuitry is hypothesized to be implicated in depressed patients with a high suicidal risk. 27 MDD patients were assessed with the Nurses Global Assessment of Suicide Risk (NGASR), following which 14 patients were classified into a high suicide risk group (NGASR ≥ 12) and 13 patients were assigned to a low suicide risk group (NGASR < 6). All 27 patients were enrolled with 25 healthy controls for resting-state magnetoencephalography (MEG). Cross-frequency coupling (CFC) measured the phase of alpha-band (8-13 Hz) as it modulated to cortical gamma-band (30-48 Hz). There was a significantly lower alpha-to-gamma phase-amplitude coupling (PAC) between the right caudate and left thalamus in high-risk suicide group compared to both the low-risk suicide group and healthy controls. The presence of a weaker coupling between the right caudate and left thalamus is indicative of a caudothalamic abnormality in suicidally depressed patients. This implies that a disruption of CSTC loop could result in executive dysfunction and working memory impairment, leading to an increased suicidal risk in MDD patients. In the future, this preliminary study has the possibility of being replicated on a larger scale, and hence validates caudothalamic dysfunction as a reliable neuroimaging biomarker for suicide in depression.


Assuntos
Ritmo alfa/fisiologia , Ritmo beta/fisiologia , Núcleo Caudado/fisiopatologia , Transtorno Depressivo Maior/fisiopatologia , Magnetoencefalografia , Rede Nervosa/fisiopatologia , Córtex Pré-Frontal/fisiopatologia , Ideação Suicida , Tálamo/fisiopatologia , Adulto , Feminino , Humanos , Masculino , Risco , Adulto Jovem
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