scholarly journals Cortical Oscillations during Gait: Wouldn’t Walking Be So Automatic?

2020 ◽  
Vol 10 (2) ◽  
pp. 90 ◽  
Author(s):  
Arnaud Delval ◽  
Madli Bayot ◽  
Luc Defebvre ◽  
Kathy Dujardin
Keyword(s):  
Posterior Parietal Cortex ◽  
Brain Activity ◽  
Muscular Activity ◽  
Cortical Activity ◽  
Muscular Contraction ◽  
Gait Pattern ◽  
Cortical Control ◽  
Time Frequency ◽  
Cortical Oscillations ◽  
Induced Changes

Gait is often considered as an automatic movement but cortical control seems necessary to adapt gait pattern with environmental constraints. In order to study cortical activity during real locomotion, electroencephalography (EEG) appears to be particularly appropriate. It is now possible to record changes in cortical neural synchronization/desynchronization during gait. Studying gait initiation is also of particular interest because it implies motor and cognitive cortical control to adequately perform a step. Time-frequency analysis enables to study induced changes in EEG activity in different frequency bands. Such analysis reflects cortical activity implied in stabilized gait control but also in more challenging tasks (obstacle crossing, changes in speed, dual tasks…). These spectral patterns are directly influenced by the walking context but, when analyzing gait with a more demanding attentional task, cortical areas other than the sensorimotor cortex (prefrontal, posterior parietal cortex, etc.) seem specifically implied. While the muscular activity of legs and cortical activity are coupled, the precise role of the motor cortex to control the level of muscular contraction according to the gait task remains debated. The decoding of this brain activity is a necessary step to build valid brain–computer interfaces able to generate gait artificially.

scholarly journals Unexpected Terrain Induced Changes in Cortical Activity in Bipedal-Walking Rats

Biology ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 36
Author(s):  
Honghao Liu ◽  
Bo Li ◽  
Minjian Zhang ◽  
Chuankai Dai ◽  
Pengcheng Xi ◽  
...  
Keyword(s):  
Brain Activity ◽  
Cortical Activity ◽  
Bipedal Walking ◽  
Normal Walking ◽  
Double Support ◽  
Uneven Terrain ◽  
Band Power ◽  
The Right ◽  
Induced Changes ◽  
The Impact

Humans and other animals can quickly respond to unexpected terrains during walking, but little is known about the cortical dynamics in this process. To study the impact of unexpected terrains on brain activity, we allowed rats with blocked vision to walk on a treadmill in a bipedal posture and then walk on an uneven area at a random position on the treadmill belt. Whole brain EEG signals and hind limb kinematics of bipedal-walking rats were recorded. After encountering unexpected terrain, the θ band power of the bilateral M1, the γ band power of the left S1, and the θ to γ band power of the RSP significantly decreased compared with normal walking. Furthermore, when the rats left uneven terrain, the β band power of the bilateral M1 and the α band power of the right M1 decreased, while the γ band power of the left M1 significantly increased compared with normal walking. Compared with the flat terrain, the θ to low β (3–20 Hz) band power of the bilateral S1 increased after the rats contacted the uneven terrain and then decreased in the single- or double- support phase. These results support the hypothesis that unexpected terrains induced changes in cortical activity.

Fatigue-induced changes in diaphragmatic afferents and cortical activity in the cat

1992 ◽  
Vol 90 (2) ◽  
pp. 213-226 ◽  
Author(s):  
E. Balzamo ◽  
F. Lagier-Tessonnier ◽  
Y. Jammes
Keyword(s):  
Cortical Activity ◽  
Induced Changes

Address of the President Sir Alan Hodgkin, O. M. at the Anniversary Meeting, 30 November 1973

1974 ◽  
Vol 185 (1078) ◽  
Keyword(s):  
Surface Membrane ◽  
Muscular Activity ◽  
Nerve Impulse ◽  
Muscular Contraction ◽  
Single Fibre ◽  
Muscle Fibres ◽  
Constant Length ◽  
Axon Membrane ◽  
Ultrastructural Studies ◽  
Mathematical Skill

The Copley Medal is awarded to Professor A. F. Huxley, F. R. S. A. F. Huxley has made outstanding contributions to our knowledge of the nerve impulse and of the mechanism by which muscle fibres are caused to contract. Jointly with Hodgkin, he introduced the powerful method of intracellular recording from nerve cells and showed that during the propagation of an impulse the mem­brane potential reverses its sign, and does not simply fall towards zero as had been widely believed. This work - interrupted by the 1939-45 war, but later resumed - led to the proposal that the impulse arises from a transient influx of sodium ions through the axon membrane. The ‘ionic theory’ of nervous conduction was then established by a series of convincing experiments and calculations for which Huxley later shared the Nobel Prize. Huxley next turned his attention to the mechanism of muscular contraction. He equipped himself for this purpose by inventing a new type of interference microscope. In experiments on living isolated muscle fibres, Huxley showed that contraction is accompanied by a shortening of the isotropic band of each sarco­mere, while the remaining portion (the anisotropic band) retains approximately constant length. His findings complemented the important ultrastructural studies of H. E. Huxley and led them both to propose a ‘sliding filament’ mechanism as the basis of muscular motion. During further microscopic observations on the living muscle fibre, A. F. Huxley produced most striking evidence on the way in which an excitatory potential change of the surface membrane is communicated, through local tubular channels, to the interior of the fibre where it activates the contractile elements. In his most recent work, A. F. Huxley has continued to develop his single-fibre technique to resolve even finer details of the dynamic changes which occur during muscular activity. His work is characterized by a rare combination of profound theoretical insight, mathematical skill and superb technical mastery, all of which has enabled him to select problems of first-rate importance and to pursue them with outstanding success.

Neural Dynamics of Context-Sensitive Adjustments in Cognitive Flexibility

2022 ◽  
pp. 1-13
Author(s):  
Audrey Siqi-Liu ◽  
Tobias Egner ◽  
Marty G. Woldorff
Keyword(s):  
Cognitive Flexibility ◽  
Switch Cost ◽  
Brain Activity ◽  
Alpha Power ◽  
Time Frequency ◽  
Context Sensitive ◽  
Electrical Brain Activity ◽  
Strong Focus ◽  
Current Task ◽  
Neural Underpinnings

Abstract To adaptively interact with the uncertainties of daily life, we must match our level of cognitive flexibility to contextual demands—being more flexible when frequent shifting between different tasks is required and more stable when the current task requires a strong focus of attention. Such cognitive flexibility adjustments in response to changing contextual demands have been observed in cued task-switching paradigms, where the performance cost incurred by switching versus repeating tasks (switch cost) scales inversely with the proportion of switches (PS) within a block of trials. However, the neural underpinnings of these adjustments in cognitive flexibility are not well understood. Here, we recorded 64-channel EEG measures of electrical brain activity as participants switched between letter and digit categorization tasks in varying PS contexts, from which we extracted ERPs elicited by the task cue and alpha power differences during the cue-to-target interval and the resting precue period. The temporal resolution of the EEG allowed us to test whether contextual adjustments in cognitive flexibility are mediated by tonic changes in processing mode or by changes in phasic, task cue-triggered processes. We observed reliable modulation of behavioral switch cost by PS context that was mirrored in both cue-evoked ERP and time–frequency effects but not by blockwide precue EEG changes. These results indicate that different levels of cognitive flexibility are instantiated after the presentation of task cues, rather than by being maintained as a tonic state throughout low- or high-switch contexts.

Cortical oscillations to measure anti-epileptic drug activity in clinical trials

2021 ◽  
Author(s):  
Andrea Biondi ◽  
Lorenzo Rocchi ◽  
Viviana Santoro ◽  
Gregory Beatch ◽  
Pierre Rossini ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Brain Activity ◽  
Systematic Evaluation ◽  
Alpha Power ◽  
Brain Oscillations ◽  
Cortical Oscillations ◽  
Anti Epileptic Drug ◽  
Beta Power ◽  
Gamma Power

Abstract The frequency analysis of electroencephalographic (EEG) activity, either spontaneous or evoked by transcranial magnetic stimulation (TMS-EEG), is a powerful tool to investigate changes in brain activity and excitability following the administration of antiepileptic drugs (AEDs). However, a systematic evaluation of the effect of AEDs on spontaneous and TMS-induced brain oscillations has not yet been provided. We studied the effects of lamotrigine, levetiracetam, and of a novel potassium channel opener (XEN1101) on TMS-induced and spontaneous brain oscillations in a group of healthy volunteers. Levetiracetam suppressed TMS-induced theta, alpha and beta power, whereas lamotrigine increased TMS-induced alpha power. XEN1101 decreased TMS-induced delta, theta and beta power. Resting-state EEG showed a decrease of theta band power after lamotrigine intake. Levetiracetam increased theta, beta and gamma power, while XEN1101 produced an increase of delta, theta, beta and gamma power. Different AEDs induce specific patterns of power changes in spontaneous and TMS-induced brain oscillations. Spontaneous and TMS-induced cortical oscillations represent a powerful tool to characterize the effect of AEDs on in vivo brain activity. Spectral fingerprints of specific AEDs should be further investigated to provide robust and objective biomarkers of biological effect in human clinical trials.

scholarly journals Three pertinent issues in the modeling of brain activity: Nonlinearities, time scales, and neural underpinnings

2000 ◽  
Vol 23 (3) ◽  
pp. 400-401 ◽  
Author(s):  
A. Daffertshofer ◽  
T. D. Frank ◽  
C. E. Peper ◽  
P. J. Beek
Keyword(s):  
Time Scales ◽  
Brain Activity ◽  
Cortical Activity ◽  
Critical Discussion ◽  
Multiple Time Scales ◽  
Multiple Time ◽  
Neural Underpinnings

A critical discussion is provided of three central assumptions underlying Nunez's approach to modeling cortical activity. A plea is made for neurophysiologically realistic models involving nonlinearities, multiple time scales, and stochasticity.

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