Attention Drives Synchronization of Alpha and Beta Rhythms between Right Inferior Frontal and Primary Sensory Neocortex

The right inferior frontal cortex (rIFC) is specifically associated with attentional control via the inhibition of behaviorally irrelevant stimuli and motor responses. Similarly, recent evidence has shown that alpha (7–14 Hz) and beta (15–29 Hz) oscillations in primary sensory neocortical areas are enhanced in the representation of non-attended stimuli, leading to the hypothesis that allocation of these rhythms plays an active role in optimal inattention. Here, we tested the hypothesis that selective synchronization between rIFC and primary sensory neocortex occurs in these frequency bands during inattention. We used magnetoencephalography to investigate phase synchrony between primary somatosensory (SI) and rIFC regions during a cued-attention tactile detection task that required suppression of response to uncertain distractor stimuli. Attentional modulation of synchrony between SI and rIFC was found in both the alpha and beta frequency bands. This synchrony manifested as an increase in the alpha-band early after cue between non-attended SI representations and rIFC, and as a subsequent increase in beta-band synchrony closer to stimulus processing. Differences in phase synchrony were not found in several proximal control regions. These results are the first to reveal distinct interactions between primary sensory cortex and rIFC in humans and suggest that synchrony between rIFC and primary sensory representations plays a role in the inhibition of irrelevant sensory stimuli and motor responses.National Institutes of Health (U.S.) (Grant P41RR14075)National Institutes of Health (U.S.) (Grant K25MH072941)National Institutes of Health (U.S.) (Grant K01AT003459)National Institutes of Health (U.S.) (Grant K24AT004095)National Institutes of Health (U.S.) (Grant RO1-NS045130-01)National Institutes of Health (U.S.) (Grant T32GM007484)National Science Foundation (U.S.) (Grant 0316933)National Science Foundation (U.S.). Graduate Research Fellowship Program (Grant DGE-1147470

Differential working memory function between phonological and visuospatial strategies: a magnetoencephalography study using a same visual task

Previous studies have reported that, in working memory, the processing of visuospatial information and phonological information have different neural bases. However, in these studies, memory items were presented via different modalities. Therefore, the modality in which the memory items were presented and the strategy for memorizing them were not rigorously distinguished. In the present study, we explored the neural basis of two working memory strategies. Nineteen right-handed young adults memorized seven sequential directions presented visually in a task in which the memory strategy was either visuospatial or phonological (visuospatial/phonological condition). Source amplitudes of theta-band (5–7 Hz) rhythm were estimated from magnetoencephalography during the maintenance period and further analyzed using cluster-based permutation tests. Behavioral results revealed that the accuracy rates showed no significant differences between conditions, while the reaction time in the phonological condition was significantly longer than that in the visuospatial condition. Theta activity in the phonological condition was significantly greater than that in the visuospatial condition, and the cluster in spatio-temporal matrix with p < 5% difference extended to right prefrontal regions in the early maintenance period and right occipito-parietal regions in the late maintenance period. The theta activity results did not indicate strategy-specific neural bases but did reveal the dynamics of executive function required for phonological processing. The functions seemed to move from attention control and inhibition control in the prefrontal region to inhibition of irrelevant information in the occipito-parietal region

Neural synchrony within the motor system: what have we learned so far?

Synchronization of neural activity is considered essential for information processing in the nervous system. Both local and inter-regional synchronization are omnipresent in different frequency regimes and relate to a variety of behavioral and cognitive functions. Over the years, many studies have sought to elucidate the question how alpha/mu, beta, and gamma synchronization contribute to motor control. Here, we review these studies with the purpose to delineate what they have added to our understanding of the neural control of movement. We highlight important findings regarding oscillations in primary motor cortex, synchronization between cortex and spinal cord, synchronization between cortical regions, as well as abnormal synchronization patterns in a selection of motor dysfunctions. The interpretation of synchronization patterns benefits from combining results of invasive and non-invasive recordings, different data analysis tools, and modeling work. Importantly, although synchronization is deemed to play a vital role, it is not the only mechanism for neural communication. Spike timing and rate coding act together during motor control and should therefore both be accounted for when interpreting movement-related activity

Hearing VS. Listening: Attention Changes the Neural Representations of Auditory Percepts

Making sense of acoustic environments is a challenging task. At any moment, the signals from distinct auditory sources arrive in the ear simultaneously, forming an acoustic mixture. The brain must represent distinct auditory objects in this complex scene and prioritize processing of relevant stimuli while maintaining the capability to react quickly to unexpected events. The present studies explore neural representations of temporal modulations and the effects of attention on these representations. Temporal modulation plays a significant role in speech perception and auditory scene analysis. To uncover how temporal modulations are processed and represented is potentially of great importance for our general understanding of the auditory system. Neural representations of compound modulations were investigated by magnetoencephalography (MEG). Interaction components are generated by near rather than distant modulation rhythms, suggesting band-limited modulation filter banks operating in the central stage of the auditory system. Furthermore, the slowest detectable neural oscillation in the auditory cortex corresponds to the perceived oscillation of the auditory percept. Interactions between stimulus-evoked and goal-related neural responses were investigated in simultaneous behavioral-neurophysiological studies, in which we manipulate subjects' attention to different components of an auditory scene. Our experimental results reveal that attention to the target correlates with a sustained increase in the neural target representation, beyond well-known transient effects. The enhancement of power and phase coherence presumably reflects increased local and global synchronizations in the brain. Furthermore, the target's perceptual detectability improves over time (several seconds), correlating strongly with the target representation's neural buildup. The change in cortical representations can be reversed in a short time-scale (several minutes) by various behavioral goals. These aforementioned results demonstrate that the neural representation of the percept is encoded using the feature-driven mechanisms of sensory cortex, but shaped in a sustained manner via attention-driven projections from higher-level areas. This adaptive neural representations occur on multiple time scales (seconds vs. minutes) and multiple spatial scales (local vs. global synchronization). Such multiple resolutions of adaptation may underlie general mechanisms of scene organization in any sensory modality and may contribute to our highly adaptive behaviors

Decoding cognition from spontaneous neural activity

In human neuroscience, studies of cognition are rarely grounded in non-task-evoked, ‘spontaneous’ neural activity. Indeed, studies of spontaneous activity tend to focus predominantly on intrinsic neural patterns (for example, resting-state networks). Taking a ‘representation-rich’ approach bridges the gap between cognition and resting-state communities: this approach relies on decoding task-related representations from spontaneous neural activity, allowing quantification of the representational content and rich dynamics of such activity. For example, if we know the neural representation of an episodic memory, we can decode its subsequent replay during rest. We argue that such an approach advances cognitive research beyond a focus on immediate task demand and provides insight into the functional relevance of the intrinsic neural pattern (for example, the default mode network). This in turn enables a greater integration between human and animal neuroscience, facilitating experimental testing of theoretical accounts of intrinsic activity, and opening new avenues of research in psychiatry

Sensorimotor Modulations by Cognitive Processes During Accurate Speech Discrimination: An EEG Investigation of Dorsal Stream Processing

Internal models mediate the transmission of information between anterior and posterior regions of the dorsal stream in support of speech perception, though it remains unclear how this mechanism responds to cognitive processes in service of task demands. The purpose of the current study was to identify the influences of attention and working memory on sensorimotor activity across the dorsal stream during speech discrimination, with set size and signal clarity employed to modulate stimulus predictability and the time course of increased task demands, respectively. Independent Component Analysis of 64–channel EEG data identified bilateral sensorimotor mu and auditory alpha components from a cohort of 42 participants, indexing activity from anterior (mu) and posterior (auditory) aspects of the dorsal stream. Time frequency (ERSP) analysis evaluated task-related changes in focal activation patterns with phase coherence measures employed to track patterns of information flow across the dorsal stream. ERSP decomposition of mu clusters revealed event-related desynchronization (ERD) in beta and alpha bands, which were interpreted as evidence of forward (beta) and inverse (alpha) internal modeling across the time course of perception events. Stronger pre-stimulus mu alpha ERD in small set discrimination tasks was interpreted as more efficient attentional allocation due to the reduced sensory search space enabled by predictable stimuli. Mu-alpha and mu-beta ERD in peri- and post-stimulus periods were interpreted within the framework of Analysis by Synthesis as evidence of working memory activity for stimulus processing and maintenance, with weaker activity in degraded conditions suggesting that covert rehearsal mechanisms are sensitive to the quality of the stimulus being retained in working memory. Similar ERSP patterns across conditions despite the differences in stimulus predictability and clarity, suggest that subjects may have adapted to tasks. In light of this, future studies of sensorimotor processing should consider the ecological validity of the tasks employed, as well as the larger cognitive environment in which tasks are performed. The absence of interpretable patterns of mu-auditory coherence modulation across the time course of speech discrimination highlights the need for more sensitive analyses to probe dorsal stream connectivity

Os códigos neurais da percepção consciente e da memória de trabalho

La Memoria de Trabajo (MT) y la cognición conciente constituyen funciones neurocognitivas íntimamente relacionadas. Si el procesamiento conciente interactúa con la información almacenada y disponible en la MT, y si el acceso a la conciencia es una condición necesaria para que cierta información sea capaz de ser retenida en la MT, entonces ciertos correlatos, mecanismos y códigos neurales podrían ser compartidos. En el presente artículo de revisión y opinión se examina de manera particular el rol en la percepción conciente y en la MT de una actividad distribuida en una red cortical fronto-parietal y la actividad oscilatoria sincronizada de poblaciones neuronales en diferentes bandas de frecuencia y en diferentes escalas espaciales. Si bien el acceso conciente y las primeras fases de codificación de información comparten parte de sus códigos neurales, la retención de información en la MT en un estado particular podría involucrar códigos adicionales. Al final del artículo se sugiere que un código neural de fase, el código theta-gamma, podría ser el mecanismo implementado por un espacio de trabajo neuronal global para codificar contenidos concientes y retener información en la MT.Working Memory (WM) and conscious cognition are intimately related neurocognitive functions. If conscious processing interacts with the information stored and available in WM, and if access to consciousness is a necessary condition for certain information to be able to be retained in WM, then certain correlates, mechanisms and neural codes could be shared. In this review and opinion article, the role in conscious perception and WM of a distributed activity in a fronto-parietal cortical network and the synchronized oscillatory activity of neuronal populations in different frequency bands and at different spatial scales is examined. Although conscious access and the first phases of information encoding share part of their neural codes, the retention of information in WM in a particular state could involve additional codes. At the end of the article it is suggested that a neural phase code, the theta-gamma code, could be the mechanism implemented by a global neuronal workspace to encode conscious contents and retain information in WM.A Memória de Trabalho (MT) e a cognição consciente constituem funções neurocognitivas intimamente relacionadas. Se o processamento consciente interage com a informação armazenada e disponível na MT, e se o acesso à consciência é uma condição necessária para que certa informação seja capaz de ser retida na MT, então certos correlatos, mecanismos e códigos neurais poderiam ser compartilhados. No presente artigo de revisão e opinião se examina de maneira particular o rol na percepção consciente e na MT de uma atividade distribuída numa rede cortical fronto-parietal e a atividade oscilatória sincronizada de populações neuronais em diferentes bandas de frequência e em diferentes escalas espaciais. Se bino acesso consciente e as primeiras fases de codificação de informação compartilham parte de seus códigos neurais, a retenção de informação na MT num estado particular poderia envolver códigos adicionais. No final do artigo sugere-se que um código neural de fase, o código theta-gamma, poderia ser o mecanismo implementado por um espaço de trabalho neuronal global para codificar conteúdos conscientes e reter informação na MT.Fil: Deleglise, Álvaro. Universidad Nacional de Rosario. Facultad de Psicología. Secretaria de Ciencia y Tecnología. Centro de Investigación En Neurociencias de Rosario; ArgentinaFil: Cervigni, Mauricio Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Centro Interdisciplinario de Investigaciones en Psicología Matemática y Experimental "Dr. Horacio J. A. Rimoldi". Grupo Vinculado CIIPME - Entre Ríos - Centro Interdisciplinario de Investigaciones en Psicología Matemática y Experimental "Dr. Horacio J. A. Rimoldi"; Argentin

Chapter Sleep Spindles – As a Biomarker of Brain Function and Plasticity

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