Cross-frequency coupling of brain oscillations in studying motivation and emotion

Research has shown that brain functions are realized by simultaneous oscillations in various frequency bands. In addition to examining oscillations in pre-specified bands, interactions and relations between the different frequency bandwidths is another important aspect that needs to be considered in unraveling the workings of the human brain and its functions. In this review we provide evidence that studying interdependencies between brain oscillations may be a valuable approach to study the electrophysiological processes associated with motivation and emotional states. Studies will be presented showing that amplitude-amplitude coupling between delta-alpha and delta-beta oscillations varies as a function of state anxiety and approach-avoidance-related motivation, and that changes in the association between delta-beta oscillations can be observed following successful psychotherapy. Together these studies suggest that cross-frequency coupling of brain oscillations may contribute to expanding our understanding of the neural processes underlying motivation and emotion.     

Temporal context in speech processing and attentional stream selection: a behavioral and neural perspective

The human capacity for processing speech is remarkable, especially given that information in speech unfolds over multiple time scales concurrently. Similarly notable is our ability to filter out of extraneous sounds and focus our attention on one conversation, epitomized by the ‘Cocktail Party’ effect. Yet, the neural mechanisms underlying on-line speech decoding and attentional stream selection are not well understood. We review findings from behavioral and neurophysiological investigations that underscore the importance of the temporal structure of speech for achieving these perceptual feats. We discuss the hypothesis that entrainment of ambient neuronal oscillations to speech’s temporal structure, across multiple time-scales, serves to facilitate its decoding and underlies the selection of an attended speech stream over other competing input. In this regard, speech decoding and attentional stream selection are examples of ‘Active Sensing’, emphasizing an interaction between proactive and predictive top-down modulation of neuronal dynamics and bottom-up sensory input.     

The processing of spatial frequency and orientation information

Three identification experiments were completed to disambiguate the associations between spatial frequency and orientation information at the sensory, decisional, and response levels. The stimuli were gratings generated by crossing four levels each of spatial frequency and orientation. In Experiment 1, the subjects made a single identification response to the stimuli. In Experiment 2, two identification responses were made, one for the spatial frequency component and the other for the orientation component. In Experiment 3, the subjects identified either the spatial frequency or the orientation component in any block of trials. The data were confusion matrices, and an information-transmission approach was used to investigate the interactions in the system. The results show that although there were sensory associations, there were no interactions at the decisional level. Performance parity was found: there was no significant difference between the single- and double-judgment paradigms in terms of information transmitted. Overall, the results suggest that although spatial frequency and orientation information is coded jointly at the sensory level, subsequent processing is independent, with each dimension drawing upon different attentional resources.     

Does cross‐frequency phase coupling of oscillatory brain activity contribute to a better understanding of visual working memory?

Nesting of fast rhythmical brain activity (gamma) into slower brain waves (theta) has frequently been suggested as a core mechanism of multi‐item working memory (WM) retention. It provides a better understanding of WM capacity limitations, and, as we discuss in this review article, it can lead to applications for modulating memory capacity. However, could cross‐frequency coupling of brain oscillations also constructively contribute to a better understanding of the neuronal signatures of working memory compatible with theoretical approaches that assume flexible capacity limits? Could a theta‐gamma code also be considered as a neural mechanism of flexible sharing of cognitive resources between memory representations in multi‐item WM? Here, we propose potential variants of theta‐gamma coupling that could explain WM retention beyond a fixed memory capacity limit of a few visual items. Moreover, we suggest how to empirically test these predictions in the future.     

Detection and discrimination of coherent motion

When viewing a pair of bars defined by the difference of spatial Gaussian functions (DOGs), human observers can discriminate accurately the relative movements of the bars, even when they differ in spatial frequency. On each trial, observers viewed two brief presentation intervals in which a pair of vertically oriented DOGs moved randomly back and forth within a restricted range. During one interval, both bars moved in the same horizontal direction and by the same magnitude (correlated movements); in the other interval, their movements were uncorrelated. When discrimination accuracy is related to the simultaneous detection of two independent movements, it was found that, if observers can detect the movements of spatially separated bars, they can tell whether their relative movements are correlated. Performance remained remarkably accurate even when the two bars differed in spatial frequency by more than two octaves or were presented separately to the two eyes. Apparently, the accurate discrimination of coherent motion involves an efficient spatial integration of optical motion information over multiple spatial locations and multiple spatial scales.     

The neuronal basis of bimanual coordination: recent neurophysiological evidence and functional models

Recent physiological studies of the neuronal processes underlying bimanual movements provide new tests for earlier functional models of bimanual coordination. The recently acquired data address three conceptual areas: the generalized motor program (GMP), intermanual crosstalk and dynamic systems models. To varying degrees, each of these concepts has aspects that can be reconciled with experimental evidence. The idea of a GMP is supported by the demonstration of abstract neuronal motor codes, e.g. bimanual-specific activity in motor cortex. The crosstalk model is consistent with the facts that hand-specific coding also exists and that interactions occur between the motor commands for each arm. Uncrossed efferent projections may underlie crosstalk on an executional level. Dynamic interhemispheric interactions through the corpus callosum may provide a high-level link at the parametric programming level, allowing flexible coupling and de-coupling. Flexible neuronal interactions could also underlie adaptive large-scale systems dynamics that can be formalized within the dynamic systems theory approach.

The correspondence of identified neuronal processes with functions of abstract models encourages the development of realistic computational models that can predict bimanual behavior on the basis of neuronal activity.     

事件相关振荡与振荡脑网络

事件相关振荡是伴随认知、情感和行为过程的脑电磁振荡活动,观察到其各类调频、调幅和调相现象,这种介观和宏观尺度上大量神经元的集体活动与微观尺度上神经元平均发放率和发放定时相互影响,共同参与神经信息的编码、表征、通讯和调控。动态细胞集群假说认为大脑认知功能是神经网络通过同步振荡相互作用的结果,在基于振荡的大脑理论指引下,多尺度、跨脑区和跨频率事件相关振荡研究为揭开振荡脑网络的工作原理带来了希望     

自我与他人视角的动态信息加工：一项行为振荡研究

为了实现流畅的社会互动,个体需要同时加工自我与他人视角下的信息,并能有效地区分二者。然而个体对自我与他人视角下的信息存在共享神经表征,那么大脑是如何在同时完成自我与他人视角信息加工的前提下又不至于混淆二者的呢？本文通过创新性的、具有高时间分辨率的内隐视觉观点采择任务,发现对于自我视角和他人视角下的信息加工存在频率约为1 Hz的行为振荡现象,并且二者存在180°左右的相位差。这一结果说明在有他人在场的社会情景中,自我视角与他人视角下的信息加工是一种具有周期性的交替优势的过程。     

A framework for local cortical oscillation patterns

Oscillations are a pervasive feature of neuronal activity in the cerebral cortex. Here, we propose a framework for understanding local cortical oscillation patterns in cognition: two classes of network interactions underlying two classes of cognitive functions produce different local oscillation patterns. Local excitatory-inhibitory interactions shape neuronal representations of sensory, motor and cognitive variables, and produce local gamma-band oscillations. By contrast, the linkage of such representations by integrative functions such as decision-making is mediated by long-range cortical interactions, which yield more diverse local oscillation patterns often involving the beta range. This framework reconciles different cortical oscillation patterns observed in recent studies and helps to understand the link between cortical oscillations and the fMRI signal. Our framework highlights the notion that cortical oscillations index the specific circuit-level mechanisms of cognition.     

Amygdala oscillations and the consolidation of emotional memories

The amygdala receives multi-modal sensory inputs and projects to virtually all levels of the central nervous system. Via these widespread projections, the amygdala facilitates consolidation of emotionally arousing memories. How the amygdala promotes synaptic plasticity elsewhere in the brain remains unknown, however. Recent work indicates that amygdala neurons show theta activity during emotional arousal, and various types of oscillations during sleep. These synchronized neuronal events could promote synaptic plasticity by facilitating interactions between neocortical storage sites and temporal lobe structures involved in declarative memory.     

Nesting of Focal Within Peripheral Vision Promotes Interactions Across Nested Time Scales in Head Sway: Multifractal Evidence From Accelerometry During Manual and Walking-Based Fitts Tasks

Nesting is a major cornerstone in ecological theorizing about visual perception, through both nesting of surface layout in locomotory movements and nesting of visually available surfaces within each other, from focal to peripheral vision. This work sought to probe these nesting relationships by examining the effects of the visual periphery on the strength of interactions among nested time scales in head sway. That is, we tested whether spatial nesting of the focal within peripheral visual fields stimulated nonlinear interactions amid temporal nesting. We examined head sway during 2 variants of the Fitts task, one involving manual pointing by seated participants and another involving walking comfortably with upright standing posture. All participants completed both tasks but were randomly assigned to experience these tasks with or without the visual periphery available. Multifractal analysis of head sway revealed that visual availability of the periphery promoted nonlinear interactions across nested time scales, but this effect depended on how much head sway extended across a plane than more ballistically along a single axis of variability.     

The proximal-to-distal sequence in upper-limb motions on multiple levels and time scales

The proximal-to-distal sequence is a phenomenon that can be observed in a large variety of motions of the upper limbs in both humans and other mammals. The mechanisms behind this sequence are not completely understood and motor control theories able to explain this phenomenon are currently incomplete. The aim of this narrative review is to take a theoretical constraints-led approach to the proximal-to-distal sequence and provide a broad multidisciplinary overview of relevant literature. This sequence exists at multiple levels (brain, spine, muscles, kinetics and kinematics) and on multiple time scales (motion, motor learning and development, growth and possibly even evolution). We hypothesize that the proximodistal spatiotemporal direction on each time scale and level provides part of the organismic constraints that guide the dynamics at the other levels and time scales. The constraint-led approach in this review may serve as a first onset towards integration of evidence and a framework for further experimentation to reveal the dynamics of the proximal-to-distal sequence.     

Examining the neural antecedents of tics in Tourette syndrome using electroencephalography

Tourette syndrome (TS) is a neurodevelopmental disorder characterized by the occurrence of motor and vocal tics. TS is associated with cortical–striatal–thalamic–cortical circuit dysfunction and hyper-excitability of cortical limbic and motor regions that lead to the occurrence of tics. Importantly, individuals with TS often report that their tics are preceded by premonitory sensory/urge phenomena (PU) that are described as uncomfortable bodily sensations that precede the execution of a tic and are experienced as an urge for motor discharge. While tics are most often referred to as involuntary movements, it has been argued by some that tics should be viewed as voluntary movements that are executed in response to the presence of PU. To investigate this issue further, we conducted a study using electroencephalography (EEG). We recorded movement-related EEG (mu- and beta-band oscillations) during (1) the immediate period leading up to the execution of voluntary movements by a group of individuals with TS and a group of matched healthy control participants, and (2) the immediate period leading up to the execution of a tic in a group of individuals with TS. We demonstrate that movement-related mu and beta oscillations are not reliably observed prior to tics in individuals with TS. We interpret this effect as reflecting the greater involvement of a network of brain areas, including the insular and cingulate cortices, the basal ganglia and the cerebellum, in the generation of tics in TS. We also show that beta-band desynchronization does occur when individuals with TS initiate voluntary movements, but, in contrast to healthy controls, desynchronization of mu-band oscillations is not observed during the execution of voluntary movements for individuals with TS. We interpret this finding as reflecting a dysfunction of physiological inhibition in TS, thereby contributing to an impaired ability to suppress neuronal populations that may compete with movement preparation processes.     

The effect of callosotomy on novel versus familiar bimanual actions: a neural dissociation between controlled and automatic processes?

The corpus collosum is the large band of fibers that connects the two cerebral hemispheres of the brain. Individuals who have had the fibers of these tracts surgically severed by callosotomy are able to draw two different spatial figures simultaneously using the left and right hands, without evidence of interactions in the spatial planning processes. Paradoxically, tasks (e.g., tying shoes) that appear to depend on spatial interactions between the left and right hands, each of which is controlled by a separate cerebral hemisphere, pose little difficulty. How can this be? In the study reported here, we observed that well-learned cooperative actions of the hands remain intact in 2 callosotomy patients, whereas actions novel to these patients are virtually impossible for them to produce without visual guidance. We infer that duplicate memory engrams of well-learned actions can be accessed by both cerebral hemispheres without callosal mediation, whereas callosal interactions are necessary for precise cross-matching of sensory information during spatial planning or perceptual-motor learning.     

Gamma神经振荡和信息整合加工

Gamma神经振荡是一种基础神经活动。它的特性使其与“信息整合加工”产生了潜在联系。已有研究显示, 自下而上的跨通道信息整合与感觉皮层的Gamma振荡同步化有关; 单通道自上而下的信息整合与高级皮层的Gamma振荡增强有关。现有的“神经耦合理论”和“匹配利用模型”分别描述了Gamma振荡如何在“自下而上”及“自上而下”的信息整合中发挥作用。Gamma振荡虽与整合加工密切相关, 但作为指标需谨慎。对于Gamma振荡在复杂情景整合加工中的作用仍待探究。     

注意过程中的行为振荡现象

行为振荡是个体心理加工过程的周期性动态变化在行为上的表现。通过高时间分辨率的行为采样方法, 行为振荡研究为探索视觉注意的时间动态结构提供了一个新的视角。各种不同的注意任务中都发现存在行为振荡现象。大量行为振荡证据表明, 注意过程存在两种主要的节律成分：反映注意抑制的α节律(8~13 Hz)和反映注意转移的θ节律(4~8 Hz)。这些结果有助于揭示注意的时间动态结构, 也为序列搜索理论和平行搜索理论之间的争论提供了新的分析思路。行为振荡的节律特征会受到一些潜在因素(如任务难度、线索有效性)的影响。行为振荡和神经振荡在某些任务中表现出相同的节律成分, 提示两者涉及了相似的心理过程。后续研究应进一步关注各种不同的注意控制过程以及多模态交互任务, 深入探索其行为振荡特点, 以更好地揭示注意的动态加工过程。     

The role of spatial frequency in the processing of hierarchically organized stimuli

Can spatial frequency differences between local and global forms account for differences in the way different levels of structure are analyzed? We examined this question by having subjects identify local or global forms of hierarchical stimuli that had beencontrast balanced. Contrast balancing eliminates low spatial frequencies, so that both local and global forms must be identified on the basis of high spatial frequency information. Response times (RTs) to global (but not local) forms were slowed for contrast-balanced stimuli, suggesting that low spatial frequencies mediate the global RT advantage typically found. In contrast, interference between local and global forms was little affected by contrast balancing or by shifts of attention between local and global forms, suggesting that it does not result from inhibitory interactions between spatial frequency channels or from temporal precedence of low versus high spatial frequency information. Finally, shifts of attention between local and global forms were also little affected by contrast balancing, suggesting that they were not based on spatial frequency.     

Visual search at different spatial scales

Treisman and Gelade's (1980) feature-integration model claims that the search for separate ("primitive") stimulus features is parallel, but that the conjunctions of those features require serial scan. Recently, evidence has accumulated that parallel processing is not limited to these "primitive" stimulus features, but that combinations of features can also produce parallel search. In the experiments reported here, the processing of feature conjunctions was studied when the stimulus features of a combination were at different spatial scales. The patterns in the search array were composed of three cross-shaped or T-shaped (local) elements, which formed an oblique bar (the global pattern) 45 deg or 135 deg in orientation. When the target and distractors differed from each other at one spatial scale only (either in the bar orientation or in the shape of the local elements), target detection was independent of the number of distractors, i.e., the search was parallel. In the conjunction task, in which the target and distractors were defined as the combinations of the bar orientation and the element shape, i.e., both spatial scales were relevant, the detection of the target required slow serial scrutiny of the search array. It is possible that the conjunction search could not be performed in parallel because switches between the two scales (or spatial frequency channels) are linked to attention and the task required the use of both scales in order to find the target.     

Parent–Child Interaction in Children with Autism Spectrum Disorder and Their Siblings: Choosing a Coding Strategy

The parent-child interaction strongly influences the emotional, behavioural, and cognitive development of young children. The nature of parent-child interactions differs in families with children with autism spectrum disorder (ASD), but research still entails a lot of inconsistencies and there is no consensus as to how these interactions should be coded. The parent-child interaction between sixteen mothers and their child with ASD (M _age?=?68 months) and a younger sibling without ASD (M _age?=?48 months) in a within-family study were coded using both a global and frequency coding scheme. Global and frequency codes of the same sample were compared to explore the value of each coding method and how they could complement each other. In addition, each coding method’s ability to detect group differences was evaluated. We found that mothers used an interaction style characterized by more support and structure, and clearer instructions in interaction with their children without ASD. In addition, global rating results suggested that within the ASD group, mothers may adapt their behaviour to the specific abilities of their child. Regarding the evaluation of coding method, results showed overlap between conceptually similar constructs included in both coding schemes. Although frequency coding clearly has its value, more qualitative aspects of the interaction were better captured by global rating scales and global rating was more time efficient. For this purpose, global ratings might be preferable over frequency coding.