Oscillatory neural activity in the gamma frequency range (>30
Hz) has been shown to accompany a wide variety of cognitive processes. So far, there has been limited success in assigning a unitary ...basic function to these oscillations, and critics have raised the argument that they could just be an epiphenomenon of neural processing. We propose a new framework that relates gamma oscillations observed in human, as well as in animal, experiments to two underlying processes: the comparison of memory contents with stimulus-related information and the utilization of signals derived from this comparison. This model attempts to explain early gamma-band responses in terms of the match between bottom-up and top-down information. Furthermore, it assumes that late gamma-band activity reflects the readout and utilization of the information resulting from this match.
The integration of sensory signals from different modalities requires flexible interaction of remote brain areas. One candidate mechanism to establish communication in the brain is transient ...synchronization of oscillatory neural signals. Although there is abundant evidence for the involvement of cortical oscillations in brain functions based on the analysis of local power, assessment of the phase dynamics among spatially distributed neuronal populations and their relevance for behavior is still sparse. In the present study, we investigated the interaction between remote brain areas by analyzing high-density electroencephalogram (EEG) data obtained from human participants engaged in a visuotactile pattern matching task. We deployed an approach for purely data-driven clustering of neuronal phase coupling in source space, which allowed imaging of large-scale functional networks in space, time and frequency without defining a priori constraints. Based on the phase coupling results, we further explored how brain areas interacted across frequencies by computing phase-amplitude coupling. Several networks of interacting sources were identified with our approach, synchronizing their activity within and across the theta (∼5 Hz), alpha (∼10 Hz), and beta (∼20 Hz) frequency bands and involving multiple brain areas that have previously been associated with attention and motor control. We demonstrate the functional relevance of these networks by showing that phase delays – in contrast to spectral power – were predictive of task performance. The data-driven analysis approach employed in the current study allowed an unbiased examination of functional brain networks based on EEG source level connectivity data. Showcased for multisensory processing, our results provide evidence that large-scale neuronal coupling is vital to long-range communication in the human brain and relevant for the behavioral outcome in a cognitive task.
•We present a purely data-driven analysis approach for EEG source connectivity data.•Oscillatory networks synchronize within and across theta, alpha and beta frequencies.•Phase and phase-amplitude coupling mediate multisensory interactions.•Phase in the observed cortical networks predicts behavioral performance.
Humans engaged in monotonous tasks are susceptible to occasional errors that may lead to serious consequences, but little is known about brain activity patterns preceding errors. Using functional MRI ...and applying independent component analysis followed by deconvolution of hemodynamic responses, we studied error preceding brain activity on a trial-by-trial basis. We found a set of brain regions in which the temporal evolution of activation predicted performance errors. These maladaptive brain activity changes started to evolve almost equal to30 sec before the error. In particular, a coincident decrease of deactivation in default mode regions of the brain, together with a decline of activation in regions associated with maintaining task effort, raised the probability of future errors. Our findings provide insights into the brain network dynamics preceding human performance errors and suggest that monitoring of the identified precursor states may help in avoiding human errors in critical real-world situations.
•Stimulus-related cortical oscillations patterns in ASD are reviewed.•No clear-cut picture of specific dysfunctional oscillation patterns has emerged.•Recent evidence points to increased ...intra-individual trial-to-trial variability in behavioral and neurophysiological responses in ASD.•Intra-individual variability represents a new avenue for the investigation of oscillatory activity in ASD.
Autism spectrum disorders (ASD) have been associated with altered neural oscillations, especially fast oscillatory activity in the gamma frequency range, suggesting fundamentally disturbed temporal coordination of activity during information processing. A detailed review of available cortical oscillation studies in ASD does not convey a clear-cut picture with respect to dysfunctional oscillation patterns in the gamma or other frequency ranges. Recent evidence suggests that instead of a general failure to activate or synchronize the cortex, there is greater intra-participant variability across behavioral, fMRI and EEG responses in ASD. Intra-individual fluctuations from one trial to another have been largely ignored in task-related neural oscillation studies of ASD, which instead have focused on mean changes in power. We highlight new avenues for the analysis of cortical oscillation patterns in ASD which are sensitive to trial-to-trial variability within the participant, in order to validate the significance of increased response variability as possible endophenotype of the disorder.
Hyper-brain studies analyze the brain activity of two or more individuals during some form of interaction. Several studies found signs of inter-subject brain activity coordination, such as power and ...phase synchronization or information flow. This hyper-brain coordination is frequently studied in paradigms which induce rhythms or even synchronization, e.g., by mirroring movements, turn-based activity in card or economic games, or joint music making. It is therefore interesting to figure out in how far coordinated brain activity may be induced by a rhythmicity in the task and/or the sensory feedback that the partners receive. We therefore studied the EEG brain activity of dyads in a task that required the smooth pursuit of a target and did not involve any extrinsic rhythms. Partners controlled orthogonal axes of the two-dimensional motion of an object that had to be kept on the target. Using several methods for analyzing hyper-brain coupling, we could not detect signs of coordinated brain activity. However, we found several brain regions in which the frequency-specific activity significantly correlated with the objective task performance, the subjective experience thereof, and of the collaboration. Activity in these regions has been linked to motor control, sensorimotor integration, executive control and emotional processing. Our results suggest that neural correlates of intersubjectivity encompass large parts of brain areas that are considered to be involved in sensorimotor control without necessarily coordinating their activity across agents.
General anesthesia is not a uniform state of the brain. Ongoing activity differs between light and deep anesthesia and cortical response properties are modulated in dependence of anesthetic dosage. ...We investigated how anesthesia level affects cross-modal interactions in primary sensory cortex. To examine this, we continuously measured the effects of visual and auditory stimulation during increasing and decreasing isoflurane level in the mouse visual cortex and the subiculum (from baseline at 0.7 to 2.5 vol % and reverse). Auditory evoked burst activity occurred in visual cortex after a transition during increase of anesthesia level. At the same time, auditory and visual evoked bursts occurred in the subiculum, even though the subiculum was unresponsive to both stimuli previous to the transition. This altered sensory excitability was linked to the presence of burst suppression activity in cortex, and to a regular slow burst suppression rhythm (~0.2 Hz) in the subiculum. The effect disappeared during return to light anesthesia. The results show that pseudo-heteromodal sensory burst responses can appear in brain structures as an effect of an anesthesia induced state change.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A systematic review was conducted to examine the findings on clinical judgment and reasoning in nursing that have emerged since Tanner’s review in A systematic review was conducted to examine the ...findings on clinical judgment and reasoning in nursing that have emerged since Tanner’s review in
2006
. Electronic databases were searched to locate primary research studies about clinical judgment and reasoning in nursing. Fifteen studies were extracted and analyzed using the five main conclusions outlined by Tanner. The findings of the systematic review generally support Tanner’s original model, although the role of experience in clinical reasoning and judgment is still not well understood or fully established. In recent literature, researchers have furthered their knowledge by using tools for improving these skills in both nursing students and practicing nurses, although no one strategy has been identified as being more effective. This is reflected in the consideration of a sixth conclusion on clinical judgment and reasoning in nursing—education strategies to improve clinical judgment may influence what a nurse brings to the situation.
J Nurs Educ.
2014;53(8):453–458.
Highlights • Acute pain is often accompanied by innocuous input that influences pain perception. • Studies on crossmodal shaping of pain have clinically relevant implications. • The principles of ...multisensory integration are applicable to crossmodal shaping of pain. • Innocuous stimuli in peripersonal space play a special role in crossmodal shaping of pain. • Power and long-range coupling of oscillations may be neural mechanisms underlying crossmodal shaping of pain.
Although non-invasive methods such as functional magnetic resonance imaging, electroencephalograms and magnetoencephalograms provide most of the current data about the human brain, their resolution ...is insufficient to show physiological processes at the cellular level. Clinical approaches sometimes allow invasive recordings to be taken from the human brain, mainly in patients with epilepsy or with movement disorders, and such recordings can sample neural activity at spatial scales ranging from single cells to distributed cell assemblies. In addition to their clinical relevance, these recordings can provide unique insights into brain functions such as movement control, perception, memory, language and even consciousness.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Abstract Cerambycidae beetles limit production and establishment of forest and fruit trees. Oncideres cervina Thomson, 1868 (Coleoptera: Cerambycidae) is one of the most important species. The ...objective was to record O. cervina girdling branches of Persea americana Mill. (Lauraceae) for the first time, check the number of oviposition incisions (Noi) as a function of the diameter of branch sections, period of emergence, and describe the larval-pupal chamber. Individuals of O. cervina were observed, for the first time, in P. americana orchards in Santa Maria, Rio Grande do Sul, Brazil. The middle section of branches (40-60 cm interval) had higher number of incisions. Girdled branches with a diameter of 40-50 mm had higher number of them. Adults emerged from November through January. Larval-pupal boreholes had diameters between 9 and 11 mm, and average tunnel length was 28 mm, with a mean volume of consumed wood of 4.3 mL. This information is useful for establishing integrated pest management practices against O. cervina in P. americana since this crop has a high added value and can be significantly compromised by attack by Cerambycidae beetles.
Resumo Os besouros da família Cerambycidae limitam a produção e o estabelecimento de essências florestais e frutíferas. Oncideres cervina Thomson, 1868 (Coleoptera: Cerambycidae) é uma das espécies mais importantes. O objetivo foi registrar O. cervina danificando ramos de Persea americana Mill. (Lauraceae) pela primeira vez, verificar o número de incisões de postura em relação ao diâmetro das secções dos ramos, período de emergência e descrever a galeria larval-pupal. Indivíduos de O. cervina foram observados pela primeira vez em pomares de P. americana em Santa Maria, Rio Grande do Sul, Brasil. A secção média dos ramos (intervalo de 40-60 cm) apresentou maior número de incisões. Ramos danificados com diâmetro de 40-50 mm tiveram maior número delas. Adultos emergiram de novembro a janeiro. Os orifícios larvais-pupais tinham diâmetros entre 9 e 11 mm, e o comprimento médio da galeria era de 28 mm, com um volume médio de madeira consumida de 4,3 mL. Essas informações são úteis para estabelecer práticas integradas de manejo de pragas contra O. cervina em P. americana, já que essa cultura tem alto valor agregado e pode ser significativamente comprometida pelo ataque de besouros da família Cerambycidae.
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