https://www.cell.com/trends/cognitive-sciences/pdf/S1364-6613(05)00242-1.pdf

A mechanism for cognitive dynamics: neuronal communication through neuronal coherence

http://www.iapsych.com/articles/bressler2010.pdf

Large-scale brain networks in cognition: emerging methods and principles

http://www.40hz.net/engel_2010_curr_opin.pdf

Beta-band oscillations--signalling the status quo?

In this review, we consider the potential functional role of beta-band oscillations, which at present is not yet well understood. We discuss evidence from recent studies on top-down mechanisms involved in cognitive processing, on the motor system and on the pathophysiology of movement disorders that suggest a unifying hypothesis: beta-band activity seems related to the maintenance of the current sensorimotor or cognitive state. We hypothesize that beta oscillations and/or coupling in the beta-band are expressed more strongly if the maintenance of the status quo is intended or predicted, than if a change is expected. Moreover, we suggest that pathological enhancement of beta-band activity is likely to result in an abnormal persistence of the status quo and a deterioration of flexible behavioural and cognitive control.

Converging evidence from electrophysiological, physiological and anatomical studies suggests that abnormalities in the synchronized oscillatory activity of neurons may have a central role in the pathophysiology of schizophrenia. Neural oscillations are a fundamental mechanism for the establishment of precise temporal relationships between neuronal responses that are in turn relevant for memory, perception and consciousness. In patients with schizophrenia, the synchronization of beta- and gamma-band activity is abnormal, suggesting a crucial role for dysfunctional oscillations in the generation of the cognitive deficits and other symptoms of the disorder. Dysfunctional oscillations may arise owing to anomalies in the brain's rhythm-generating networks of GABA (gamma-aminobutyric acid) interneurons and in cortico-cortical connections.

Abnormal neural oscillations and synchrony in schizophrenia

Because of attentional limitations, the human visual system can process for awareness and response only a fraction of the input received. Lesion and functional imaging studies have identified frontal, temporal, and parietal areas as playing a major role in the attentional control of visual processing, but very little is known about how these areas interact to form a dynamic attentional network. We hypothesized that the network communicates by means of neural phase synchronization, and we used magnetoencephalography to study transient long-range interarea phase coupling in a well studied attentionally taxing dual-target task (attentional blink). Our results reveal that communication within the fronto-parieto-temporal attentional network proceeds via transient long-range phase synchronization in the beta band. Changes in synchronization reflect changes in the attentional demands of the task and are directly related to behavioral performance. Thus, we show how attentional limitations arise from the way in which the subsystems of the attentional network interact.

/pdf/modulation-of-long-range-neural-synchrony-reflects-temporal-4rya3z9ot9.pdf

Modulation of long-range neural synchrony reflects temporal limitations of visual attention in humans.

Everyday human behaviour relies on our ability to predict outcomes on the basis of moment by moment information. Long-range neural phase synchronization has been hypothesized as a mechanism by which ‘predictions’ can exert an effect on the processing of incoming sensory events. Using magnetoencephalography (MEG) we have studied the relationship between the modulation of phase synchronization in a cerebral network of areas involved in visual target processing and the predictability of target occurrence. Our results reveal a striking increase in the modulation of phase synchronization associated with an increased probability of target occurrence. These observations are consistent with the hypothesis that long-range phase synchronization plays a critical functional role in humans' ability to effectively employ predictive heuristics.

/pdf/anticipatory-control-of-long-range-phase-synchronization-3ytokgsjtj.pdf

Anticipatory control of long‐range phase synchronization

The ability to adapt to environmental changes is based on the impressive capacity of the central nervous system for plasticity changes. A better understanding of the requirements of neuroplasticity will help to apprehend and predict the success of sensory prostheses. To investigate neuroplastic changes associated with (1) blindfolding and (2) the use of a mobile visual–auditory substitution system, five normally sighted adults underwent weekly measurements of neuromagnetic activity using a 122-channel whole head neuromagnetometer. The substitution device converted visual images into sound patterns. During measurements subjects listened to “geometric sounds” converted from images of geometric shapes, “natural sounds” representing photographs of everyday objects, as well as to original “environmental sounds”. To assess the role of visual deprivation, three individuals were blindfolded throughout a 3-week testing period. To assess the effect of extended exposure to “visual sounds”, three subjects—two blindfolded, one sighted—had free use of the substitution device. Neuromagnetic responses were restricted to the auditory cortex across all measurements. Activity at 100 ms after presentation of “natural sounds”, but not other auditory stimuli, showed a significant enhancement over time only in blindfolded subjects using the substitution system, indicating that the combination of visual deprivation and practice facilitated intra-modal plasticity. The fact that changes occurred only in response to “natural sounds” probably reflects the increased behavioural relevance of this category evident only for blindfolded subjects using the substitution device.

Irmtraud Schnitzler

Papers

Modulation of long-range neural synchrony reflects temporal limitations of visual attention in humans.

Anticipatory control of long‐range phase synchronization

Image-to-sound conversion: experience-induced plasticity in auditory cortex of blindfolded adults.

Modulation of Long-Range Neural Synchrony Associated with Changes in Visual Attention