The Attenuation of Very Low Frequency Brain Oscillations in Transitions from a Rest State to Active Attention

2009 ◽  
Vol 23 (4) ◽  
pp. 191-198 ◽  
Author(s):  
Suzannah K. Helps ◽  
Samantha J. Broyd ◽  
Christopher J. James ◽  
Anke Karl ◽  
Edmund J. S. Sonuga-Barke
Keyword(s):  
Brain Activity ◽  
Sampling Rate ◽  
Low Frequency ◽  
Future Research ◽  
Adhd Symptoms ◽  
Default Mode ◽  
Very Low Frequency ◽  
Wide Range ◽  
Interference Hypothesis ◽  
Mode Interference

Background: The default mode interference hypothesis ( Sonuga-Barke & Castellanos, 2007 ) predicts (1) the attenuation of very low frequency oscillations (VLFO; e.g., .05 Hz) in brain activity within the default mode network during the transition from rest to task, and (2) that failures to attenuate in this way will lead to an increased likelihood of periodic attention lapses that are synchronized to the VLFO pattern. Here, we tested these predictions using DC-EEG recordings within and outside of a previously identified network of electrode locations hypothesized to reflect DMN activity (i.e., S3 network; Helps et al., 2008 ). Method: 24 young adults (mean age 22.3 years; 8 male), sampled to include a wide range of ADHD symptoms, took part in a study of rest to task transitions. Two conditions were compared: 5 min of rest (eyes open) and a 10-min simple 2-choice RT task with a relatively high sampling rate (ISI 1 s). DC-EEG was recorded during both conditions, and the low-frequency spectrum was decomposed and measures of the power within specific bands extracted. Results: Shift from rest to task led to an attenuation of VLFO activity within the S3 network which was inversely associated with ADHD symptoms. RT during task also showed a VLFO signature. During task there was a small but significant degree of synchronization between EEG and RT in the VLFO band. Attenuators showed a lower degree of synchrony than nonattenuators. Discussion: The results provide some initial EEG-based support for the default mode interference hypothesis and suggest that failure to attenuate VLFO in the S3 network is associated with higher synchrony between low-frequency brain activity and RT fluctuations during a simple RT task. Although significant, the effects were small and future research should employ tasks with a higher sampling rate to increase the possibility of extracting robust and stable signals.

scholarly journals Shared genetic influences on ADHD symptoms and very low-frequency EEG activity: a twin study

2011 ◽  
Vol 53 (6) ◽  
pp. 706-715 ◽  
Author(s):  
Charlotte Tye ◽  
Frühling Rijsdijk ◽  
Corina U. Greven ◽  
Jonna Kuntsi ◽  
Philip Asherson ◽  
...  
Keyword(s):  
Twin Study ◽  
Low Frequency ◽  
Genetic Influences ◽  
Adhd Symptoms ◽  
Eeg Activity ◽  
Very Low Frequency ◽  
Shared Genetic

scholarly journals Astronomy from a Lunar Base

1995 ◽  
Vol 166 ◽  
pp. 347-350
Author(s):  
S. Volonte
Keyword(s):  
Dark Matter ◽  
Low Frequency ◽  
Particle Spectrum ◽  
Human Intervention ◽  
The Moon ◽  
Astronomical Observations ◽  
Very Low Frequency ◽  
Long Baseline ◽  
Wide Range ◽  
The Universe

The Moon is generally considered to be an ideal site for astronomy, offering excellent observing conditions and access to the entire electromagnetic and particle spectrum. A wide range of astronomical observations can be carried out from the Moon, but, as concluded in a recent ESA study (Mission to the Moon 1992), only a restricted number could be better implemented from a lunar site rather than from any other location. Very low frequency (VLF) astronomy, astrometry and interferometry fall into this category, as well as a transit telescope to map dark matter in the Universe. Whilst VLF and astrometric telescopes should be automatic, long baseline interferometers will probably require human intervention and will thus benefit from a manned lunar base.

scholarly journals Polyploidy in Gymnosperms: Revisited

2005 ◽  
Vol 54 (1-6) ◽  
pp. 59-69 ◽  
Author(s):  
M. Raj Ahuja
Keyword(s):  
Low Frequency ◽  
Current Status ◽  
Chromosome Behavior ◽  
Very Low Frequency ◽  
Juniperus Chinensis ◽  
Wide Range ◽  
Potential Applications ◽  
Future Potential ◽  
Growth Abnormalities ◽  
Fitzroya Cupressoides

Abstract There are only a few natural polyploids in gymnosperms. These have been reported in Ephera spp. (Gnetales), and Juniperus chinensis ‘Pfitzeriana’ (2n = 4x = 44), Fitzroya cupressoides (2n = 4x = 44), and the only hexaploid conifer Sequoia sempervirens (2n = 6x = 66) (Coniferales). Sporadic polyploids and aneuploids occur at a very low frequency in nurseries in conifers, but most of them show growth abnormalities, remain dwarf, and may not reach maturity. One exception is an autotetraploid tree of Larix decidua (2n = 4x = 48) that has survived in a private estate in Denmark. Colchicine-induced polyploids (colchiploids) have been produced in a several genera of conifers, including, Pinus, Picea, and Larix. These colchiploids (Co) were hybridized to untreated diploids to produce C1 and C2 generations to investigate their chromosome behavior. The colchiploids showed a wide range of chromosome variability, ranging from diploids, triploids, and tetraploids, and many were mixoploids. The colchiploids also show growth retardation, remain dwarf, and their future potential applications in forestry remains uncertain. However, genetic variability in the colchiploids still offers prospects for isolating genetically stable new genotypes. Even though polyploidy is rare in extant conifers, is it possible that ancient polyploidy or paleopolyploidy, that is prevalent in angiosperms, has also played a role in the evolution of conifers. In this paper we shall review the current status of polyploidy in gymnosperms.

scholarly journals Ultra-fast magnetic resonance encephalography of physiological brain activity – Glymphatic pulsation mechanisms?

2015 ◽  
Vol 36 (6) ◽  
pp. 1033-1045 ◽  
Author(s):  
Vesa Kiviniemi ◽  
Xindi Wang ◽  
Vesa Korhonen ◽  
Tuija Keinänen ◽  
Timo Tuovinen ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Cerebrospinal Fluid ◽  
Magnetic Resonance ◽  
Brain Activity ◽  
Low Frequency ◽  
Physiological Mechanisms ◽  
Very Low Frequency ◽  
Novel Approach ◽  
Signal Change ◽  
Methodological Advance

The theory on the glymphatic convection mechanism of cerebrospinal fluid holds that cardiac pulsations in part pump cerebrospinal fluid from the peri-arterial spaces through the extracellular tissue into the peri-venous spaces facilitated by aquaporin water channels. Since cardiac pulses cannot be the sole mechanism of glymphatic propulsion, we searched for additional cerebrospinal fluid pulsations in the human brain with ultra-fast magnetic resonance encephalography. We detected three types of physiological mechanisms affecting cerebral cerebrospinal fluid pulsations: cardiac, respiratory, and very low frequency pulsations. The cardiac pulsations induce a negative magnetic resonance encephalography signal change in peri-arterial regions that extends centrifugally and covers the brain in ≈1 Hz cycles. The respiratory ≈0.3 Hz pulsations are centripetal periodical pulses that occur dominantly in peri-venous areas. The third type of pulsation was very low frequency (VLF 0.001–0.023 Hz) and low frequency (LF 0.023–0.73 Hz) waves that both propagate with unique spatiotemporal patterns. Our findings using critically sampled magnetic resonance encephalography open a new view into cerebral fluid dynamics. Since glymphatic system failure may precede protein accumulations in diseases such as Alzheimer's dementia, this methodological advance offers a novel approach to image brain fluid dynamics that potentially can enable early detection and intervention in neurodegenerative diseases.

Coupling of sympathetic nerve traffic and BP at very low frequencies is mediated by large-amplitude events

2003 ◽  
Vol 284 (3) ◽  
pp. R802-R810 ◽  
Author(s):  
Don E. Burgess ◽  
David C. Randall ◽  
Richard O. Speakman ◽  
David R. Brown
Keyword(s):  
Sympathetic Nerve ◽  
Wavelet Transforms ◽  
Large Amplitude ◽  
Low Frequency ◽  
Functional Connection ◽  
Low Frequencies ◽  
Very Low Frequency ◽  
Arterial Blood ◽  
Wide Range ◽  
Transient Events

This study explores the functional association between renal sympathetic nerve traffic (NT) and arterial blood pressure (BP) in the very-low-frequency range (i.e., <0.1 Hz). NT and BP ( n = 6) or BP alone ( n = 17) was recorded in unanesthetized rats ( n = 6). Data were collected for 2–5 h, and wavelet transforms were calculated from data epochs of up to 1 h. From these transforms, we obtained probability distributions for fluctuation amplitudes over a range of time scales. We also computed the cross-wavelet power spectrum between NT and BP to detect the occurrence in time of large-amplitude transient events that may be important in the autonomic regulation of BP. Finally, we computed a time sequence of cross correlations between NT and BP to follow the relationship between NT and BP in time. We found that NT and BP follow comparable self-similar scaling relationships (i.e., NT and BP fluctuations exhibit a certain type of power law behavior). Scaling of this nature 1) points to underlying dynamics over a wide range of scales and 2) is related to large-amplitude events that contribute to the very-low-frequency variability of NT and BP. There is a strong correlation between NT and BP during many of these transient events. These strong correlations and the uniformity in scaling imply a functional connection between these two signals at frequencies where we previously found no connection using spectral coherence.

scholarly journals Dynamics of task-induced modulation of spontaneous brain activity and functional connectivity in the triple resting-state networks assessed using the visual oddball paradigm

PLoS ONE ◽  
2021 ◽  
Vol 16 (11) ◽  
pp. e0246709
Author(s):  
Hasan Sbaihat ◽  
Ravichandran Rajkumar ◽  
Shukti Ramkiran ◽  
Abed Al-Nasser Assi ◽  
N. Jon Shah ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Resting State ◽  
Brain Activity ◽  
Large Body ◽  
Reaction Times ◽  
Low Frequency ◽  
Oddball Paradigm ◽  
Wide Range ◽  
Visual Oddball Paradigm ◽  
Visual Oddball

The default mode network (DMN), the salience network (SN), and the central executive network (CEN) are considered as the core resting-state brain networks (RSN) due to their involvement in a wide range of cognitive tasks. Despite the large body of knowledge related to their regional spontaneous activity (RSA) and functional connectivity (FC) of these networks, less is known about the dynamics of the task-associated modulation on these parameters and the task-induced interaction between these three networks. We have investigated the effects of the visual-oddball paradigm on three fMRI measures (amplitude of low-frequency fluctuations for RSA, regional homogeneity for local FC, and degree centrality for global FC) in these three core RSN. A rest-task-rest paradigm was used and the RSNs were identified using independent component analysis (ICA) on the resting-state data. The observed patterns of change differed noticeably between the networks and were tightly associated with the task-related brain activity and the distinct involvement of the networks in the performance of the single subtasks. Furthermore, the inter-network analysis showed an increased synchronization of CEN with the DMN and the SN immediately after the task, but not between the DMN and SN. Higher pre-task inter-network synchronization between the DMN and the CEN was associated with shorter reaction times and thus better performance. Our results provide some additional insights into the dynamics within and between the triple RSN. Further investigations are required in order to understand better their functional importance and interplay.

scholarly journals The Generation of ULF/ELF/VLF Waves in the Ionosphere by Modulated Heating

Universe ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 29
Author(s):  
Zhe Guo ◽  
Hanxian Fang ◽  
Farideh Honary
Keyword(s):  
High Frequency ◽  
Modulation Frequency ◽  
Source Region ◽  
Low Frequency ◽  
Future Research ◽  
Very Low Frequency ◽  
The Past ◽  
Ionospheric Modification ◽  
Vlf Waves ◽  
Scientific Achievements

One of the most important effects of ionospheric modification by high power, high frequency (HF) waves is the generation of ultra low frequency/extremely low frequency/very low frequency (ULF/ELF/VLF) waves by modulated heating. This paper reviews the scientific achievements of the past five decades regarding the main mechanisms of excitation of ULF/ELF/VLF waves and discusses their characteristics, such as their electrojet dependency, the location of the source region, continuous and discontinuous waves, the number of HF arrays, and the suitable range of the modulation frequency for different proposed mechanisms. Finally, the outlook for future research in this area is presented.

Comparative Effects of High-Tech Visual Scene Displays and Low-Tech Isolated Picture Symbols on Engagement From Students With Multiple Disabilities

2019 ◽  
Vol 50 (4) ◽  
pp. 693-702 ◽  
Author(s):  
Christine Holyfield ◽  
Sydney Brooks ◽  
Allison Schluterman
Keyword(s):  
Language Learning ◽  
Augmentative And Alternative Communication ◽  
Visual Analysis ◽  
Multiple Disabilities ◽  
Visual Scene ◽  
Future Research ◽  
High Tech ◽  
Single Subject ◽  
Wide Range ◽  
The Difference

Purpose Augmentative and alternative communication (AAC) is an intervention approach that can promote communication and language in children with multiple disabilities who are beginning communicators. While a wide range of AAC technologies are available, little is known about the comparative effects of specific technology options. Given that engagement can be low for beginning communicators with multiple disabilities, the current study provides initial information about the comparative effects of 2 AAC technology options—high-tech visual scene displays (VSDs) and low-tech isolated picture symbols—on engagement. Method Three elementary-age beginning communicators with multiple disabilities participated. The study used a single-subject, alternating treatment design with each technology serving as a condition. Participants interacted with their school speech-language pathologists using each of the 2 technologies across 5 sessions in a block randomized order. Results According to visual analysis and nonoverlap of all pairs calculations, all 3 participants demonstrated more engagement with the high-tech VSDs than the low-tech isolated picture symbols as measured by their seconds of gaze toward each technology option. Despite the difference in engagement observed, there was no clear difference across the 2 conditions in engagement toward the communication partner or use of the AAC. Conclusions Clinicians can consider measuring engagement when evaluating AAC technology options for children with multiple disabilities and should consider evaluating high-tech VSDs as 1 technology option for them. Future research must explore the extent to which differences in engagement to particular AAC technologies result in differences in communication and language learning over time as might be expected.

Understanding Limited Use of Amplification in Infants and Children Who Are Hard of Hearing

2015 ◽  
Vol 25 (1) ◽  
pp. 15-23 ◽  
Author(s):  
Ryan W. McCreery ◽  
Elizabeth A. Walker ◽  
Meredith Spratford
Keyword(s):  
Hard Of Hearing ◽  
Hearing Aid ◽  
Management Strategies ◽  
Infants And Children ◽  
Future Research ◽  
Research Needs ◽  
Case Examples ◽  
Hearing Aid Use ◽  
Wide Range ◽  
In Infants And Children

The effectiveness of amplification for infants and children can be mediated by how much the child uses the device. Existing research suggests that establishing hearing aid use can be challenging. A wide range of factors can influence hearing aid use in children, including the child's age, degree of hearing loss, and socioeconomic status. Audiological interventions, including using validated prescriptive approaches and verification, performing on-going training and orientation, and communicating with caregivers about hearing aid use can also increase hearing aid use by infants and children. Case examples are used to highlight the factors that influence hearing aid use. Potential management strategies and future research needs are also discussed.

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