scholarly journals The Detection of Phase Amplitude Coupling During Sensory Processing

2017 ◽  
Author(s):  
R.A Seymour ◽  
G. Rippon ◽  
K. Kessler
Keyword(s):  
Visual Processing ◽  
Low Frequency ◽  
Methodological Issues ◽  
Trial Length ◽  
Sinusoidal Oscillations ◽  
Practical Guidelines ◽  
Alpha 7 ◽  
Time Courses ◽  
Phase Amplitude ◽  
Post Hoc

1.AbstractThere is increasing interest in understanding how the phase and amplitude of distinct neural oscillations might interact to support dynamic communication within the brain. In particular, previous work has demonstrated a coupling between the phase of low frequency oscillations and the amplitude (or power) of high frequency oscillations during certain tasks, termed phase amplitude coupling (PAC). For instance, during visual processing in humans, PAC has been reliably observed between ongoing alpha (8-13Hz) and gamma-band (>40Hz) activity. However, the application of PAC metrics to electrophysiological data can be challenging due to numerous methodological issues and lack of coherent approaches within the field. Therefore, in this article we outline the various analysis steps involved in detecting PAC, using an openly available MEG dataset from 16 participants performing an interactive visual task. Firstly, we localised gamma and alpha-band power using the Fieldtrip toolbox, and extracted time courses from area V1, defined using a multimodal parcellation scheme. These V1 responses were analysed for changes in alpha-gamma PAC, using four common algorithms. Results showed an increase in gamma (40-100Hz) - alpha (7-13Hz) PAC in response to the visual grating stimulus, though specific patterns of coupling were somewhat dependent upon the algorithm employed. Additionally, post-hoc analyses showed that these results were not driven by the presence of non-sinusoidal oscillations, and that trial length was sufficient to obtain reliable PAC estimates. Finally, throughout the article, methodological issues and practical guidelines for ongoing PAC research will be discussed.

scholarly journals The significance of Gerta Vrbová's low-frequency stimulation experiment

2021 ◽  
Author(s):  
Dirk Pette
Keyword(s):  
Low Frequency ◽  
Basic Research ◽  
Contractile Properties ◽  
Scientific Cooperation ◽  
Low Frequency Stimulation ◽  
Slow Twitch Muscle ◽  
Frequency Stimulation ◽  
Time Courses ◽  
Fast Twitch

An inspiring scientific cooperation has come to an end, when Gerta Vrbová, an internationally renowned researcher in the field of neuromuscular interactions, passed away on October 2, 2020. Comparative EMG studies had led Gerta to suggest that different contractile properties of fast- and slow-twitch muscle fibers relate to specific firing patterns of their motoneurones. In support of her hypothesis, long term stimulation of fast-twitch muscles with a stimulus pattern resembling that of slow motoneurones, were shown to induce a pronounced fast-to-slow shift in contractile properties. In our cooperation which started in 1970, and also in cooperation with others, Gerta's experiment proved to be an ideal model for the study of neurally controlled changes in phenotype characteristics at various levels of molecular and cellular organization, their time courses and ranges. It has become most important in basic research on the adaptive potential or plasticity of muscle.

scholarly journals The effect of cannabidiol (CBD) on low-frequency activity and functional connectivity in the brain of adults with and without autism spectrum disorder (ASD)

2019 ◽  
Vol 33 (9) ◽  
pp. 1141-1148 ◽  
Author(s):  
Charlotte M Pretzsch ◽  
Bogdan Voinescu ◽  
Maria A Mendez ◽  
Robert Wichers ◽  
Laura Ajram ◽  
...  
Keyword(s):  
Autism Spectrum Disorder ◽  
Functional Connectivity ◽  
Low Frequency ◽  
Random Order ◽  
Autism Spectrum ◽  
Spectrum Disorder ◽  
Double Blind ◽  
Drug Challenge ◽  
The Right ◽  
Post Hoc

Background: The potential benefits of cannabis and its major non-intoxicating component cannabidiol (CBD) are attracting attention, including as a potential treatment in neurodevelopmental disorders such as autism spectrum disorder (ASD). However, the neural action of CBD, and its relevance to ASD, remains unclear. We and others have previously shown that response to drug challenge can be measured using functional magnetic resonance imaging (fMRI), but that pharmacological responsivity is atypical in ASD. Aims: We hypothesized that there would be a (different) fMRI response to CBD in ASD. Methods: To test this, task-free fMRI was acquired in 34 healthy men (half with ASD) following oral administration of 600 mg CBD or matched placebo (random order; double-blind administration). The ‘fractional amplitude of low-frequency fluctuations’ (fALFF) was measured across the whole brain, and, where CBD significantly altered fALFF, we tested if functional connectivity (FC) of those regions was also affected by CBD. Results: CBD significantly increased fALFF in the cerebellar vermis and the right fusiform gyrus. However, post-hoc within-group analyses revealed that this effect was primarily driven by the ASD group, with no significant change in controls. Within the ASD group only, CBD also significantly altered vermal FC with several of its subcortical (striatal) and cortical targets, but did not affect fusiform FC with other regions in either group. Conclusion: Our results suggest that, especially in ASD, CBD alters regional fALFF and FC in/between regions consistently implicated in ASD. Future studies should examine if this affects the complex behaviours these regions modulate.

Dissociating early and late visual processing via the Ebbinghaus illusion

2016 ◽  
Vol 33 ◽  
Author(s):  
FILIPP SCHMIDT ◽  
ANDREAS WEBER ◽  
ANKE HABERKAMP
Keyword(s):  
Visual Processing ◽  
High Frequency ◽  
Time Course ◽  
Temporal Dynamics ◽  
Low Frequency ◽  
Response Speed ◽  
Ebbinghaus Illusion ◽  
Priming Effects ◽  
Parvocellular Pathway ◽  
The Difference

AbstractVisual perception is not instantaneous; the perceptual representation of our environment builds up over time. This can strongly affect our responses to visual stimuli. Here, we study the temporal dynamics of visual processing by analyzing the time course of priming effects induced by the well-known Ebbinghaus illusion. In slower responses, Ebbinghaus primes produce effects in accordance with their perceptual appearance. However, in fast responses, these effects are reversed. We argue that this dissociation originates from the difference between early feedforward-mediated gist of the scene processing and later feedback-mediated more elaborate processing. Indeed, our findings are well explained by the differences between low-frequency representations mediated by the fast magnocellular pathway and high-frequency representations mediated by the slower parvocellular pathway. Our results demonstrate the potentially dramatic effect of response speed on the perception of visual illusions specifically and on our actions in response to objects in our visual environment generally.

Head-Trunk Coordination During Linear Anterior-Posterior Translations

2003 ◽  
Vol 89 (4) ◽  
pp. 1891-1901 ◽  
Author(s):  
Emily A. Keshner
Keyword(s):  
Vestibular System ◽  
Healthy Subjects ◽  
Low Frequency ◽  
Head Acceleration ◽  
Response Latencies ◽  
Distraction Task ◽  
Analysis System ◽  
Post Hoc ◽  
Linear Accelerometer ◽  
Anterior Posterior

The purpose of this study was to evaluate the relative contributions of inputs from the vestibular system and the trunk to head-trunk coordination. Twelve healthy adults and 6 adults with diminished bilateral labyrinthine input (LD) were seated with their trunk either fixed to the seat or free to move. Subjects received 10-cm, 445-cm/s2 anterior-posterior ramps and 0.35- to 4.05-Hz sum-of-sines translations while performing a mental distraction task in the dark. Kinematics of the head and trunk were derived from an Optotrak motion analysis system and a linear accelerometer placed on the head. EMG signals were collected from neck and paraspinal muscles. Data were tested for significance with multivariate ANOVA (MANOVA) and Bonferroni post hoc analyses. Initial linear and angular head acceleration directions differed in healthy subjects when the trunk was fixed or free, but did not differ in LD subjects. Peak head angular accelerations were significantly greater with the trunk fixed than when free, and were greater in LD than in control subjects. EMG response latencies did not differ when the trunk was fixed or free. Low-frequency phase responses in the healthy subjects were close to 90° and had a delayed descent as frequency increased, suggesting some neural compensation that was absent in the LD subjects. Results of this study revealed a strong initial reliance on system mechanics and on signals from segmental receptors. The vestibular system may act to damp later response components and to monitor the position of the head in space secondary to feedback from segmental proprioceptors rather than to generate the postural reactions.

scholarly journals Needle-Free Electroacupuncture for Postoperative Pain Management

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Daniel Lee ◽  
Hong Xu ◽  
Jaung-Geng Lin ◽  
Kerry Watson ◽  
Rick Sai Chuen Wu ◽  
...  
Keyword(s):  
Postoperative Pain ◽  
Low Frequency ◽  
Postoperative Pain Management ◽  
Control Group ◽  
High Frequency Stimulation ◽  
Double Blind ◽  
Group 4 ◽  
Frequency Stimulation ◽  
Post Hoc ◽  
Stimulation Group

This study examined the effects of needle-free electroacupuncture, at ST36 on postoperative pain following hysterectomy. Based on a double-blind, sham, and different intervention controlled clinical experimental design, 47 women were randomly allocated to four different groups. Except for those in the control group (Group 1,n=13), a course of treatment was given of either sham (Group 2,n=12), high-frequency stimulation (Group 3,n=12), or low-frequency stimulation (Group 4,n=10). All groups were assessed during the postoperative period for 24 hours. The Visual Analogue Scale was used to determine the amount of perceived pain felt by each subject. Differences were found between the means postoperatively at three, four, eight, 16, and 24 hours. Post hoc comparison tests indicated that Group 4 was significantly different from Groups 1, 2, and 3 at 24 hours. A one-way ANOVA analysis for total patient-controlled analgesia demand and doses indicated significant differences between the groupsF(3,42)=3.59,P<.05. Post hoc analysis confirmed the differences between Groups 1 (M=84.54) and 4 (M=41.60). Treatment outcomes of this therapy showed a positive effect for the management of postoperative pain.

scholarly journals Mixed-Methods Design in Biology Education Research: Approach and Uses

2016 ◽  
Vol 15 (4) ◽  
pp. rm5 ◽  
Author(s):  
Abdi-Rizak M. Warfa
Keyword(s):  
Education Research ◽  
Mixed Methods ◽  
Educational Research ◽  
Mixed Methods Research ◽  
Biology Education ◽  
Research Approach ◽  
Mixed Methods Design ◽  
Methodological Issues ◽  
Practical Guidelines ◽  
Single Method

Educational research often requires mixing different research methodologies to strengthen findings, better contextualize or explain results, or minimize the weaknesses of a single method. This article provides practical guidelines on how to conduct such research in biology education, with a focus on mixed-methods research (MMR) that uses both quantitative and qualitative inquiries. Specifically, the paper provides an overview of mixed-methods design typologies most relevant in biology education research. It also discusses common methodological issues that may arise in mixed-methods studies and ways to address them. The paper concludes with recommendations on how to report and write about MMR.

scholarly journals Different Coupling Modes Mediate Cortical Cross-Frequency Interactions

2015 ◽  
Author(s):  
Randolph F Helfrich ◽  
Christoph S Herrmann ◽  
Andreas K Engel ◽  
Till R Schneider
Keyword(s):  
Information Integration ◽  
Visual Processing ◽  
High Frequency ◽  
Low Frequency ◽  
Gamma Oscillations ◽  
Frequency Component ◽  
High Frequency Component ◽  
Alpha Power ◽  
Alpha Oscillation ◽  
Transcranial Alternating Current Stimulation

Cross-frequency coupling (CFC) has been suggested to constitute a highly flexible mechanism for cortical information gating and processing, giving rise to conscious perception and various higher cognitive functions in humans. In particular, it might provide an elegant tool for information integration across several spatiotemporal scales within nested or coupled neuronal networks. However, it is currently unknown whether low frequency (theta/alpha) or high frequency gamma oscillations orchestrate cross-frequency interactions, raising the question of who is master and who is slave. While correlative evidence suggested that at least two distinct CFC modes exist, namely phase-amplitude-coupling (PAC) and amplitude-envelope-correlations (AEC), it is currently unknown whether they subserve distinct cortical functions. Novel non-invasive brain stimulation tools, such as transcranial alternating current stimulation (tACS), now provide the unique opportunity to selectively entrain the low or high frequency component and study subsequent effects on CFC. Here, we demonstrate the differential modulation of CFC during selective entrainment of alpha or gamma oscillations. Our results reveal that entrainment of the low frequency component increased PAC, where gamma power became preferentially locked to the trough of the alpha oscillation, while gamma-band entrainment reduced alpha power through enhanced AECs. These results provide causal evidence for the functional role of coupled alpha and gamma oscillations for visual processing.

scholarly journals Altered Temporal Dynamic Intrinsic Brain Activity in Late Blindness

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
Xin Huang ◽  
Zhi Wen ◽  
Chen-Xing Qi ◽  
Yan Tong ◽  
Han-Dong Dan ◽  
...  
Keyword(s):  
Visual Processing ◽  
Brain Activity ◽  
Gaussian Random Field ◽  
Low Frequency ◽  
Sliding Window ◽  
Crossmodal Plasticity ◽  
The Difference ◽  
Structural Architecture ◽  
The Right ◽  
Intrinsic Brain Activity

Previous neuroimaging studies demonstrated that visual deprivation triggers significant crossmodal plasticity in the functional and structural architecture of the brain. However, prior neuroimaging studies focused on the static brain activity in blindness. It remains unknown whether alterations of dynamic intrinsic brain activity occur in late blindness (LB). This study investigated dynamic intrinsic brain activity changes in individuals with late blindness by assessing the dynamic amplitude of low-frequency fluctuations (dALFFs) using sliding-window analyses. Forty-one cases of late blindness (LB) (29 males and 12 females, mean age: 39.70±12.66 years) and 48 sighted controls (SCs) (17 males and 31 females, mean age: 43.23±13.40 years) closely matched in age, sex, and education level were enrolled in this study. The dALFF with sliding-window analyses was used to compare the difference in dynamic intrinsic brain activity between the two groups. Compared with SCs, individuals with LB exhibited significantly lower dALFF values in the bilateral lingual gyrus (LING)/calcarine (CAL) and left thalamus (THA). LB cases also showed considerably decreased dFC values between the bilateral LING/CAL and the left middle frontal gyrus (MFG) and between the left THA and the right LING/cerebelum_6 (CER) (two-tailed, voxel-level P<0.01, Gaussian random field (GRF) correction, cluster-level P<0.05). Our study demonstrated that LB individuals showed lower-temporal variability of dALFF in the visual cortices and thalamus, suggesting lower flexibility of visual thalamocortical activity, which might reflect impaired visual processing in LB individuals. These findings indicate that abnormal dynamic intrinsic brain activity might be involved in the neurophysiological mechanisms of LB.

scholarly journals The significance of Gerta Vrbová's low-frequency stimulation experiment

2021 ◽  
Author(s):  
Dirk Pette
Keyword(s):  
Low Frequency ◽  
Basic Research ◽  
Contractile Properties ◽  
Scientific Cooperation ◽  
Low Frequency Stimulation ◽  
Slow Twitch Muscle ◽  
Frequency Stimulation ◽  
Time Courses ◽  
Fast Twitch

An inspiring scientific cooperation has come to an end, when Gerta Vrbová, an internationally renowned researcher in the field of neuromuscular interactions, passed away on October 2, 2020. Comparative EMG studies had led Gerta to suggest that different contractile properties of fast- and slow-twitch muscle fibers relate to specific firing patterns of their motoneurones. In support of her hypothesis, long term stimulation of fast-twitch muscles with a stimulus pattern resembling that of slow motoneurones, were shown to induce a pronounced fast-to-slow shift in contractile properties. In our cooperation which started in 1970, and also in cooperation with others, Gerta's experiment proved to be an ideal model for the study of neurally controlled changes in phenotype characteristics at various levels of molecular and cellular organization, their time courses and ranges. It has become most important in basic research on the adaptive potential or plasticity of muscle.

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