Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 180
Filtrar
1.
J Neurosci ; 44(19)2024 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-38548339

RESUMO

Perception is a probabilistic process dependent on external stimulus properties and one's internal state. However, which internal states influence perception and via what mechanisms remain debated. We studied how spontaneous alpha-band activity (8-13 Hz) and pupil fluctuations impact visual detection and confidence across stimulus contrast levels (i.e., the contrast response function, CRF). In human subjects of both sexes, we found that low prestimulus alpha power induced an "additive" shift in the CRF, whereby stimuli were reported present more frequently at all contrast levels, including contrast of zero (i.e., false alarms). Conversely, prestimulus pupil size had a "multiplicative" effect on detection such that stimuli occurring during large pupil states (putatively corresponding to higher arousal) were perceived more frequently as contrast increased. Signal detection modeling reveals that alpha power changes detection criteria equally across the CRF but not detection sensitivity (d'), whereas pupil-linked arousal modulated sensitivity, particularly for higher contrasts. Interestingly, pupil size and alpha power were positively correlated, meaning that some of the effect of alpha on detection may be mediated by pupil fluctuations. However, pupil-independent alpha still induced an additive shift in the CRF corresponding to a criterion effect. Our data imply that low alpha boosts detection and confidence by an additive factor, rather than by a multiplicative scaling of contrast responses, a profile which captures the effect of pupil-linked arousal. We suggest that alpha power and arousal fluctuations have dissociable effects on behavior. Alpha reflects the baseline level of visual excitability, which can vary independent of arousal.


Assuntos
Ritmo alfa , Nível de Alerta , Pupila , Humanos , Feminino , Masculino , Pupila/fisiologia , Nível de Alerta/fisiologia , Adulto , Ritmo alfa/fisiologia , Adulto Jovem , Estimulação Luminosa/métodos , Percepção Visual/fisiologia , Sensibilidades de Contraste/fisiologia
2.
Cereb Cortex ; 34(3)2024 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-38436467

RESUMO

Previous working memory research has demonstrated robust stimulus representations during memory maintenance in both voltage and alpha-band activity in electroencephalography. However, the exact functions of these 2 neural signatures have remained controversial. Here we systematically investigated their respective contributions to memory manipulation. Human participants either maintained a previously seen spatial location, or manipulated the location following a mental rotation cue over a delay. Using multivariate decoding, we observed robust location representations in low-frequency voltage and alpha-band oscillatory activity with distinct spatiotemporal dynamics: location representations were most evident in posterior channels in alpha-band activity, but were most prominent in the more anterior, central channels in voltage signals. Moreover, the temporal emergence of manipulated representation in central voltage preceded that in posterior alpha-band activity, suggesting that voltage might carry stimulus-specific source signals originated internally from anterior cortex, whereas alpha-band activity might reflect feedback signals in posterior cortex received from higher-order cortex. Lastly, while location representations in both signals were coded in a low-dimensional neural subspace, location representation in central voltage was higher-dimensional and underwent a representational transformation that exclusively predicted memory behavior. Together, these results highlight the crucial role of central voltage in working memory, and support functional distinctions between voltage and alpha-band activity.


Assuntos
Córtex Cerebral , Memória de Curto Prazo , Humanos , Eletroencefalografia
3.
Neuroimage ; 290: 120565, 2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38453102

RESUMO

People tend to perceive the same information differently depending on whether it is expressed in an individual or a group frame. It has also been found that the individual (vs. group) frame of expression tends to lead to more charitable giving and greater tolerance of wealth inequality. However, little is known about whether the same resource allocation in social interactions elicits distinct responses depending on proposer type. Using the second-party punishment task, this study examined whether the same allocation from different proposers (individual vs. group) leads to differences in recipient behavior and the neural mechanisms. Behavioral results showed that reaction times were longer in the unfair (vs. fair) condition, and this difference was more pronounced when the proposer was the individual (vs. group). Neural results showed that proposer type (individual vs. group) influenced early automatic processing (indicated by AN1, P2, and central alpha band), middle processing (indicated by MFN and right frontal theta band), and late elaborative processing (indicated by P3 and parietal alpha band) of fairness in resource allocation. These results revealed more attentional resources were captured by the group proposer in the early stage of fairness processing, and more cognitive resources were consumed by processing group-proposed unfair allocations in the late stage, possibly because group proposers are less identifiable than individual proposers. The findings provide behavioral and neural evidence for the effects of "individual/group" framing leading to cognitive differences. They also deliver insights into social governance issues, such as punishing individual and/or group violations.


Assuntos
Eletroencefalografia , Jogos Experimentais , Humanos , Potenciais Evocados/fisiologia , Interação Social , Punição/psicologia
4.
Brain Topogr ; 38(1): 2, 2024 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-39367155

RESUMO

Frequent listening to unfamiliar music excerpts forms functional connectivity in the brain as music becomes familiar and memorable. However, where these connections spectrally arise in the cerebral cortex during music familiarization has yet to be determined. This study investigates electrophysiological changes in phase-based functional connectivity recorded with electroencephalography (EEG) from twenty participants' brains during thrice passive listening to initially unknown classical music excerpts. Functional connectivity is evaluated based on measuring phase synchronization between all pairwise combinations of EEG electrodes across all repetitions via repeated measures ANOVA and between every two repetitions of listening to unknown music with the weighted phase lag index (WPLI) method in different frequency bands. The results indicate an increased phase synchronization during gradual short-term familiarization between the right frontal and the right parietal areas in the theta and alpha bands. In addition, the increased phase synchronization is discovered between the right temporal areas and the right parietal areas at the theta band during gradual music familiarization. Overall, this study explores the short-term music familiarization effects on neural responses by revealing that repetitions form phasic coupling in the theta and alpha bands in the right hemisphere during passive listening.


Assuntos
Ritmo alfa , Percepção Auditiva , Eletroencefalografia , Lobo Frontal , Música , Lobo Parietal , Ritmo Teta , Humanos , Masculino , Feminino , Ritmo alfa/fisiologia , Adulto Jovem , Lobo Parietal/fisiologia , Ritmo Teta/fisiologia , Adulto , Percepção Auditiva/fisiologia , Lobo Frontal/fisiologia , Eletroencefalografia/métodos , Lobo Temporal/fisiologia , Reconhecimento Psicológico/fisiologia , Estimulação Acústica/métodos
5.
Cereb Cortex ; 33(3): 634-650, 2023 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-35244170

RESUMO

Tracking and predicting the temporal structure of nociceptive inputs is crucial to promote survival, as proper and immediate reactions are necessary to avoid actual or potential bodily injury. Neural activities elicited by nociceptive stimuli with different temporal structures have been described, but the neural processes responsible for translating nociception into pain perception are not fully elucidated. To tap into this issue, we recorded electroencephalographic signals from 48 healthy participants receiving thermo-nociceptive stimuli with 3 different durations and 2 different intensities. We observed that pain perception and several brain responses are modulated by stimulus duration and intensity. Crucially, we identified 2 sustained brain responses that were related to the emergence of painful percepts: a low-frequency component (LFC, < 1 Hz) originated from the insula and anterior cingulate cortex, and an alpha-band event-related desynchronization (α-ERD, 8-13 Hz) generated from the sensorimotor cortex. These 2 sustained brain responses were highly coupled, with the α-oscillation amplitude that fluctuated with the LFC phase. Furthermore, the translation of stimulus duration into pain perception was serially mediated by α-ERD and LFC. The present study reveals how brain responses elicited by nociceptive stimulation reflect the complex processes occurring during the translation of nociceptive information into pain perception.


Assuntos
Nociceptividade , Dor , Humanos , Nociceptividade/fisiologia , Percepção da Dor/fisiologia , Eletroencefalografia , Giro do Cíngulo/fisiologia
6.
Cereb Cortex ; 33(6): 2982-2996, 2023 03 10.
Artigo em Inglês | MEDLINE | ID: mdl-35811300

RESUMO

Temporal order judgment of two successive tactile stimuli delivered to our hands is often inverted when we cross our hands. The present study aimed to identify time-frequency profiles of the interactions across the cortical network associated with the crossed-hand tactile temporal order judgment task using magnetoencephalography. We found that the interactions across the cortical network were channeled to a low-frequency band (5-10 Hz) when the hands were uncrossed. However, the interactions became activated in a higher band (12-18 Hz) when the hands were crossed. The participants with fewer inverted judgments relied mainly on the higher band, whereas those with more frequent inverted judgments (reversers) utilized both. Moreover, reversers showed greater cortical interactions in the higher band when their judgment was correct compared to when it was inverted. Overall, the results show that the cortical network communicates in two distinctive frequency modes during the crossed-hand tactile temporal order judgment task. A default mode of communications in the low-frequency band encourages inverted judgments, and correct judgment is robustly achieved by recruiting the high-frequency mode.


Assuntos
Julgamento , Percepção do Tato , Humanos , Tato , Mãos
7.
Hum Brain Mapp ; 44(15): 5065-5078, 2023 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-37515386

RESUMO

Adopting highly sensitive multivariate electroencephalography (EEG) and alpha-band decoding analyses, the present study investigated proactive and reactive language control during bilingual language production. In a language-switching task, Chinese-English bilinguals were asked to name pictures based on visually presented cues. EEG and alpha-band decoding accuracy associated with switch and non-switch trials were used as indicators for inhibition over the non-target language. Multivariate EEG decoding analyses showed that the decoding accuracy in L1 but not in L2, was above chance level shortly after cue onset. In addition, alpha-band decoding results showed that the decoding accuracy in L1 rose above chance level in an early time window and a late time window locked to the stimulus. Together, these asymmetric patterns of decoding accuracy indicate that both proactive and reactive attentional control over the dominant L1 are exerted during bilingual word production, with a possibility of overlap between two control mechanisms. We addressed theoretical implications based on these findings for bilingual language control models.


Assuntos
Multilinguismo , Humanos , Idioma , Eletroencefalografia , Atenção/fisiologia , Sinais (Psicologia) , Potenciais Evocados/fisiologia
8.
J Sleep Res ; 32(5): e13916, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-37156757

RESUMO

It has long been thought that links between affect and sleep are bidirectional. However, few studies have directly assessed the relationships between: (1) pre-sleep affect and sleep electroencephalogram (EEG) activity; and (2) sleep EEG activity and post-sleep affect. This study aims to systematically explore the correlations between pre-/post-sleep affect and EEG activity during sleep. In a community sample of adults (n = 51), we measured participants' positive and negative affect in the evening before sleep and in the next morning after sleep. Participants slept at their residence for 1 night of EEG recording. Using Fourier transforms, the EEG power at each channel was estimated during rapid eye movement sleep and non-rapid eye movement sleep for the full range of sleep EEG frequencies. We first present heatmaps of the raw correlations between pre-/post-sleep affect and EEG power during rapid eye movement and non-rapid eye movement sleep. We then thresholded the raw correlations with a medium effect size |r| ≥ 0.3. Using a cluster-based permutation test, we identified a significant cluster indicating a negative correlation between pre-sleep positive affect and EEG power in the alpha frequency range during rapid eye movement sleep. This result suggests that more positive affect during the daytime may be associated with less fragmented rapid eye movement sleep that night. Overall, our exploratory results lay the foundation for confirmatory research on the relationship between daytime affect and sleep EEG activity.


Assuntos
Eletroencefalografia , Sono , Adulto , Humanos , Sono REM
9.
Brain Topogr ; 36(4): 517-534, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-37198376

RESUMO

Previous researches state vision as a vital source of information for movement control and more precisely for accurate hand movement. Further, fine bimanual motor activity may be associated with various oscillatory activities within distinct brain areas and inter-hemispheric interactions. However, neural coordination among the distinct brain areas responsible to enhance motor accuracy is still not adequate. In the current study, we investigated task-dependent modulation by simultaneously measuring high time resolution electroencephalogram (EEG), electromyogram (EMG) and force along with bi-manual and unimanual motor tasks. The errors were controlled using visual feedback. To complete the unimanual tasks, the participant was asked to grip the strain gauge using the index finger and thumb of the right hand thereby exerting force on the connected visual feedback system. Whereas the bi-manual task involved finger abduction of the left index finger in two contractions along with visual feedback system and at the same time the right hand gripped using definite force on two conditions that whether visual feedback existed or not for the right hand. Primarily, the existence of visual feedback for the right hand significantly decreased brain network global and local efficiency in theta and alpha bands when compared with the elimination of visual feedback using twenty participants. Brain network activity in theta and alpha bands coordinates to facilitate fine hand movement. The findings may provide new neurological insight on virtual reality auxiliary equipment and participants with neurological disorders that cause movement errors requiring accurate motor training. The current study investigates task-dependent modulation by simultaneously measuring high time resolution electroencephalogram, electromyogram and force along with bi-manual and unimanual motor tasks. The findings show that visual feedback for right hand decreases the force root mean square error of right hand. Visual feedback for right hand decreases local and global efficiency of brain network in theta and alpha bands.


Assuntos
Controle Comportamental , Retroalimentação Sensorial , Humanos , Mãos , Movimento , Dedos , Desempenho Psicomotor , Lateralidade Funcional
10.
Cereb Cortex ; 32(6): 1260-1268, 2022 03 04.
Artigo em Inglês | MEDLINE | ID: mdl-34411242

RESUMO

Recent studies reveal that attention operates in a rhythmic manner, that is, sampling each location or feature alternatively over time. However, most evidence derives from top-down tasks, and it remains elusive whether bottom-up processing also entails dynamic coordination. Here, we developed a novel feature processing paradigm and combined time-resolved behavioral measurements and electroencephalogram (EEG) recordings to address the question. Specifically, a salient color in a multicolor display serves as a noninformative cue to capture attention and presumably reset the oscillations of feature processing. We then measured the behavioral performance of a probe stimulus associated with either high- or low-salient color at varied temporal lags after the cue. First, the behavioral results (i.e., reaction time) display an alpha-band (~8 Hz) profile with a consistent phase lag between high- and low-salient conditions. Second, simultaneous EEG recordings show that behavioral performance is modulated by the phase of alpha-band neural oscillation at the onset of the probes. Finally, high- and low-salient probes are associated with distinct preferred phases of alpha-band neural oscillations. Taken together, our behavioral and neural results convergingly support a central function of alpha-band rhythms in feature processing, that is, features with varied saliency levels are processed at different phases of alpha neural oscillations.


Assuntos
Atenção , Eletroencefalografia , Ritmo alfa , Eletroencefalografia/métodos , Estimulação Luminosa/métodos , Tempo de Reação
11.
Conscious Cogn ; 107: 103436, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36495699

RESUMO

When people close their eyes, the power of alpha-band oscillatory brain activity increases. We explored the possibility that this could be related to a suppression of visual processing, rather than being a default dynamic of the visual brain. We recorded brain activity while people meditated with their eyes open or closed, and when people attended to or imagined having auditory or visual experiences. We could decode the attended or imagined modality of experiences based on the spectra of brain activity that prevailed while meditating with open or closed eyes. We also found anecdotal evidence suggesting the strength of imagined sensory experiences may be predicted by the dynamics of neural networks that are responsive to inputs. Overall, our data suggest spectra changes when people close their eyes might relate to a targeted suppression of visual processing, as opposed to being a default state of idle visual brains.


Assuntos
Atenção , Encéfalo , Humanos , Estimulação Luminosa , Percepção Visual , Imaginação , Ritmo alfa
12.
Acta Anaesthesiol Scand ; 67(7): 877-884, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37096645

RESUMO

INTRODUCTION: Preoperative cognitive impairments increase the risk of postoperative complications. The electroencephalogram (EEG) could provide information on cognitive vulnerability. The feasibility and clinical relevance of sleep EEG (EEGsleep ) compared to intraoperative EEG (EEGintraop ) in cognitive risk stratification remains to be explored. We investigated similarities between EEGsleep and EEGintraop vis-a-vis preoperative cognitive impairments. METHODS: Pilot study including 27 patients (63 year old [53.5, 70.0]) to whom Montreal cognitive assessment (MoCA) and EEGsleep were administered 1 day before a propofol-based general anaesthesia, in addition to EEGintraop acquisition from depth-of-anaesthesia monitors. Sleep spindles on EEGsleep and intraoperative alpha-band power on EEGintraop were particularly explored. RESULTS: In total, 11 (41%) patients had a MoCA <25 points. These patients had a significantly lower sleep spindle power on EEGsleep (25 vs. 40 µv2 /Hz, p = .035) and had a weaker intraoperative alpha-band power on EEGintraop (85 vs. 150 µv2 /Hz, p = .001) compared to patients with normal MoCA. Correlation between sleep spindle and intraoperative alpha-band power was positive and significant (r = 0.544, p = .003). CONCLUSION: Preoperative cognitive impairment appears to be detectable by both EEGsleep and EEGintraop . Preoperative sleep EEG to assess perioperative cognitive risk is feasible but more data are needed to demonstrate its benefit compared to intraoperative EEG.


Assuntos
Anestesia , Disfunção Cognitiva , Humanos , Pessoa de Meia-Idade , Projetos Piloto , Sono , Eletroencefalografia , Disfunção Cognitiva/diagnóstico , Biomarcadores
13.
Neuroimage ; 250: 118929, 2022 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-35077852

RESUMO

Oscillatory neural dynamics are highly non-stationary and require methods capable of quantifying time-resolved changes in oscillatory activity in order to understand neural function. Recently, a method termed 'frequency sliding' was introduced to estimate the instantaneous frequency of oscillatory activity, providing a means of tracking temporal changes in the dominant frequency within a sub-band of field potential recordings. Here, the ability of frequency sliding to recover ground-truth oscillatory frequency in simulated data is tested while the exponent (slope) of the 1/fx component of the signal power spectrum is systematically varied, mimicking real electrophysiological data. The results show that 1) in the presence of 1/f activity, frequency sliding systematically underestimates the true frequency of the signal, 2) the magnitude of underestimation is correlated with the steepness of the slope, suggesting that, if unaccounted for, slope changes could be misinterpreted as frequency changes, 3) the impact of slope on frequency estimates interacts with oscillation amplitude, indicating that changes in oscillation amplitude alone may also influence instantaneous frequency estimates in the presence of strong 1/f activity; and 4) analysis parameters such as filter bandwidth and location also mediate the influence of slope on estimated frequency, indicating that these settings should be considered when interpreting estimates obtained via frequency sliding. The origin of these biases resides in the output of the filtering step of frequency sliding, whose energy is biased towards lower frequencies precisely because of the 1/f structure of the data. We discuss several strategies to mitigate these biases and provide a proof-of-principle for a 1/f normalization strategy.


Assuntos
Ondas Encefálicas/fisiologia , Eletroencefalografia , Conectoma/métodos , Fenômenos Eletrofisiológicos , Humanos
14.
Neuroimage ; 264: 119759, 2022 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-36417950

RESUMO

There is much debate about the neural mechanisms that achieve suppression of salient distracting stimuli during visual search. The proactive suppression hypothesis asserts that if exposed to the same distractors repeatedly, these stimuli are actively inhibited before attention can be shifted to them. A contrasting proposal holds that attention is initially captured by salient distractors but is subsequently withdrawn. By concurrently measuring stimulus-driven and intrinsic brain potentials in 36 healthy human participants, we obtained converging evidence against early proactive suppression of distracting input. Salient distractors triggered negative event-related potentials (N1pc/N2pc), enhanced the steady-state visual evoked potential (SSVEP) relative to non-salient (filler) stimuli, and suppressed contralateral relative to ipsilateral alpha-band amplitudes-three electrophysiological measure associated with the allocation of attention-even though these distractors did not interfere with behavioral responses to the search targets. Furthermore, these measures indicated that both stimulus-driven and goal-driven allocations of attention occurred in conjunction with one another, with the goal-driven effect enhancing and prolonging the stimulus-driven effect. These results provide a new perspective on the traditional dichotomy between bottom-up and top-down attentional allocation. Control experiments revealed that continuous marking of the locations at which the search display items were presented resulted in a dramatic and unexpected conversion of the target-elicited N2pc into a shorter-latency N1pc in association with faster reaction times to the targets.


Assuntos
Eletroencefalografia , Potenciais Evocados Visuais , Humanos , Atenção/fisiologia , Potenciais Evocados/fisiologia , Tempo de Reação/fisiologia , Percepção Visual/fisiologia
15.
Neuroimage ; 252: 119041, 2022 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-35231630

RESUMO

Our mental representation of egocentric space is influenced by the disproportionate sensory perception of the body. Previous studies have focused on the neural architecture for egocentric representations within the visual field. However, the space representation underlying the body is still unclear. To address this problem, we applied both functional Magnitude Resonance Imaging (fMRI) and Magnetoencephalography (MEG) to a spatial-memory paradigm by using a virtual environment in which human participants remembered a target location left, right, or back relative to their own body. Both experiments showed larger involvement of the frontoparietal network in representing a retrieved target on the left/right side than on the back. Conversely, the medial temporal lobe (MTL)-parietal network was more involved in retrieving a target behind the participants. The MEG data showed an earlier activation of the MTL-parietal network than that of the frontoparietal network during retrieval of a target location. These findings suggest that the parietal cortex may represent the entire space around the self-body by coordinating two distinct brain networks.


Assuntos
Percepção Espacial , Campos Visuais , Mapeamento Encefálico , Humanos , Imageamento por Ressonância Magnética , Rememoração Mental/fisiologia , Lobo Parietal/diagnóstico por imagem , Lobo Parietal/fisiologia , Percepção Espacial/fisiologia , Lobo Temporal/fisiologia
16.
Int J Neuropsychopharmacol ; 25(6): 457-467, 2022 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-35137108

RESUMO

BACKGROUND: Pursuing goals is compromised when being confronted with interfering information. In such situations, conflict monitoring is important. Theoretical considerations on the neurobiology of response selection and control suggest that auricular transcutaneous vagus nerve stimulation (atVNS) should modulate conflict monitoring. However, the neurophysiological-functional neuroanatomical underpinnings are still not understood. METHODS: AtVNS was applied in a randomized crossover study design (n = 45). During atVNS or sham stimulation, conflict monitoring was assessed using a Flanker task. EEG data were recorded and analyzed with focus on theta and alpha band activity. Beamforming was applied to examine functional neuroanatomical correlates of atVNS-induced EEG modulations. Moreover, temporal EEG signal decomposition was applied to examine different coding levels in alpha and theta band activity. RESULTS: AtVNS compromised conflict monitoring processes when it was applied at the second appointment in the crossover study design. On a neurophysiological level, atVNS exerted specific effects because only alpha-band activity was modulated. Alpha-band activity was lower in middle and superior prefrontal regions during atVNS stimulation and thus lower when there was also a decline in task performance. The same direction of alpha-band modulations was evident in fractions of the alpha-band activity coding stimulus-related processes, stimulus-response translation processes, and motor response-related processes. CONCLUSIONS: The combination of prior task experience and atVNS compromises conflict monitoring processes. This is likely due to reduction of the alpha-band-associated inhibitory gating process on interfering information in frontal cortices. Future research should pay considerable attention to boundary conditions affecting the direction of atVNS effects.


Assuntos
Estimulação do Nervo Vago , Estudos Cross-Over , Eletroencefalografia , Lobo Frontal , Nervo Vago
17.
Conscious Cogn ; 100: 103317, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35364385

RESUMO

AIM: This study investigated the bromazepam effects in male subjects during the time estimation performance and EEG alpha asymmetry in electrodes associated with the frontal and motor cortex. MATERIAL AND METHODS: This is a double-blind, crossover study with a sample of 32 healthy adults under control (placebo) vs. experimental (bromazepam) during visual time-estimation task in combination with electroencephalographic analysis. RESULTS: The results demonstrated that the bromazepam increased the relative error in the 4 s, 7 s, and 9 s intervals (p = 0.001). In addition, oral bromazepam modulated the EEG alpha asymmetry in cortical areas during the time judgment (p ≤ 0.025). CONCLUSION: The bromazepam decreases the precision of time estimation judgments and modulates the EEG alpha asymmetry, with greater left hemispheric dominance during time perception. Our findings suggest that bromazepam influences internal clock synchronization via the modulation of GABAergic receptors, strongly relating to attention, conscious perception, and behavioral performance.


Assuntos
Bromazepam , Percepção do Tempo , Adulto , Bromazepam/farmacologia , Estudos Cross-Over , Método Duplo-Cego , Eletroencefalografia/métodos , Humanos , Julgamento , Masculino
18.
J Physiol ; 599(13): 3385-3402, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33963545

RESUMO

KEY POINTS: It is theorized that the nervous system controls groups of muscles together as functional units, or 'synergies', resulting in correlated electromyographic (EMG) signals among muscles. However, such correlation does not necessarily imply group-level neural control. Oscillatory synchronization (coherence) among EMG signals implies neural coupling, but it is not clear how this relates to control of muscle synergies. EMG was recorded from seven arm muscles of 10 adult participants rotating an upper limb ergometer, and EMG-EMG coherence, EMG amplitude correlations and their relationship with each other were characterized. A novel method to derive multi-muscle synergies from EMG-EMG coherence is presented and these are compared with classically defined synergies. Coherent alpha-band (8-16 Hz) drive was strongest among muscles whose gross activity levels are well correlated within a given task. The cross-muscle distribution and temporal modulation of coherent alpha-band drive suggests a possible role in the neural coordination/monitoring of synergies. ABSTRACT: During movement, groups of muscles may be controlled together by the nervous system as an adaptable functional entity, or 'synergy'. The rules governing when (or if) this occurs during voluntary behaviour in humans are not well understood, at least in part because synergies are usually defined by correlated patterns of muscle activity without regard for the underlying structure of their neural control. In this study, we investigated the extent to which comodulation of muscle output (i.e. correlation of electromyographic (EMG) amplitudes) implies that muscles share intermuscular neural input (assessed via EMG-EMG coherence analysis). We first examined this relationship among pairs of upper limb muscles engaged in an arm cycling task. We then applied a novel multidimensional EMG-EMG coherence analysis allowing synergies to be characterized on the basis of shared neural drive. We found that alpha-band coherence (8-16 Hz) is related to the degree to which overall muscle activity levels correlate over time. The extension of this coherence analysis to describe the cross-muscle distribution and temporal modulation of alpha-band drive revealed a close match to the temporal and structural features of traditionally defined muscle synergies. Interestingly, the coherence-derived neural drive was inversely associated with, and preceded, changes in EMG amplitudes by ∼200 ms. Our novel characterization of how alpha-band neural drive is dynamically distributed among muscles is a fundamental step forward in understanding the neural origins and correlates of muscle synergies.


Assuntos
Movimento , Músculo Esquelético , Adulto , Eletromiografia , Humanos , Sistema Nervoso , Extremidade Superior
19.
Brain Cogn ; 151: 105733, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33915402

RESUMO

The aim of the present study was to investigate (a) the neural correlates of a love induction task (LIT) including listening to love-related songs and thinking about the romantic relationship, and (b) the effects of romantic love on the emotional processing of love-unrelated stimuli during a passive viewing task. The EEG was recorded in two groups of university students: people in love (Love Group, LG, N = 22, 19 F) and people not in love (Control Group, CG, N = 20, 15 F). The LIT induced higher pleasantness and arousal in the LG than in the CG, as well as higher alpha activity in occipital-right electrodes, suggesting active mental imagery and internal focused attention. During the picture viewing task, the LG displayed larger N1 amplitudes than the CG in response to unpleasant pictures, and lower amplitudes of the late positive potential to both pleasant and unpleasant pictures at frontal sites. Overall, these results suggest an early attentional modulation of the neural responses to unpleasant, mood-incongruent cues, followed by an implicit emotional down-regulation of arousing stimuli, which might have important implications for everyday attitudes and behaviors.


Assuntos
Eletroencefalografia , Amor , Nível de Alerta , Atenção , Emoções , Potenciais Evocados , Humanos , Estimulação Luminosa
20.
Brain Cogn ; 147: 105662, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33360042

RESUMO

The successful resolution of ever-changing conflicting contexts requires efficient cognitive control. Previous studies have found similar neural patterns in conflict processing for different modalities using an event-related potential (ERP) approach and have concluded that cognitive control is supramodal. However, recent behavioral studies have found that conflict adaptation (a phenomenon with the reduction of congruency effect in the current trial after an incongruent trial as compared with a congruent trial) could not transfer across visual and auditory modalities and suggested that cognitive control is modality-specific, challenging the supramodal view. These discrepancies may have also arisen from methodological differences across studies. The current study examined the electroencephalographic profiles of a Stroop-like task to elucidate the modality-specific neural mechanisms of cognitive control. Participants were instructed to respond to a target always coming from the visual modality while disregarding the distractor coming from either the auditory or the visual modality. The results revealed significant congruency effects on both behavioral indices, i.e., reaction time and error rate, and ERP components, including the P3 and the conflict slow potential. Besides, the congruency effects on the amplitude of the P3 showed a negative correlation with reaction time, indicating an intrinsic link between these neural and behavioral indices. Furthermore, in the modality-repetition condition, conflict adaptation effects were significant on both reaction time and P3 amplitude, and the reaction time could be predicted by the P3 amplitude, while such effects were not observed in the modality-alternation condition. The time-frequency analysis also showed that conflict adaptation occurred in the modality-repetition condition, but not in the modality-alternation condition in low frequency bands, including the theta (4-8 Hz), alpha (8-12 Hz), and beta1 (12-20 Hz) bands. Taken together, our results revealed modality-specific patterns of the conflict adaptation effects on the P3 amplitude and oscillatory power (in theta, alpha, and beta1 bands), providing neural evidence for the modality specificity of cognitive control and expanding the boundaries of cognitive control.


Assuntos
Conflito Psicológico , Potenciais Evocados , Cognição , Eletroencefalografia , Humanos , Tempo de Reação , Teste de Stroop
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA