scholarly journals Entraining corticocortical plasticity changes oscillatory activity in action control and inhibition

2020 ◽  
Author(s):  
Alejandra Sel ◽  
Lennart Verhagen ◽  
Katharina Angerer ◽  
Raluca David ◽  
Miriam Klein-Flügge ◽  
...  
Keyword(s):  
Motor System ◽  
Primary Motor Cortex ◽  
Premotor Cortex ◽  
Oscillatory Activity ◽  
Induction Effect ◽  
Cortical Connectivity ◽  
Functional Changes ◽  
State Dependent ◽  
Excitatory State ◽  
Before And After

SummaryOscillatory activity may reflect interactions between brain areas[1]. Here we tested whether inducing corticocortical plasticity in a specific set of connections changes oscillatory activity and cortico-cortical interactions and, if this is the case, whether the changes manifest in a manner that is behaviour state-dependent. We either increased or decreased the influence of activity in human ventral premotor cortex (PMv) over activity in primary motor cortex (M1) using cortico-cortical paired associative stimulation (ccPAS)[2, 3]. Before and after stimulation participants performed a Go/No-Go task. While M1 TMS pulses revealed the excitatory state of the motor system at specific time points, the electroencephalogram (EEG) revealed the evolution of oscillatory activity dynamics in the motor system over several hundreds of milliseconds before, during, and after each movement. Augmenting cortical connectivity between PMv and M1, by evoking synchronous pre- and postsynaptic activity in the PMv-M1 pathways, led to a state-dependent modulation of the causal influence of PMv over M1, and at the same time, enhanced oscillatory beta and theta rhythms in Go and No-Go trials, respectively. No changes were observed in the alpha rhythm. The plasticity induction effect was dependent on PMv-M1 stimulation order; the opposite patterns of results were observed after an equal amount of stimulation of PMv and M1 but applied in a temporal pattern that did not augment PMv’s influence over M1. These results are consistent with Hebbian principles of synaptic plasticity[4] and show that artificial manipulation of cortico-cortical connectivity produces state-dependent functional changes in the spectral fingerprints of the motor circuit.

Corticospinal Tract Microstructure Correlates With Beta Oscillatory Activity in the Primary Motor Cortex After Stroke

Stroke ◽  
2021 ◽  
Author(s):  
Robert Schulz ◽  
Marlene Bönstrup ◽  
Stephanie Guder ◽  
Jingchun Liu ◽  
Benedikt Frey ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Fractional Anisotropy ◽  
Primary Motor Cortex ◽  
Supplementary Motor Area ◽  
Premotor Cortex ◽  
Motor Impairment ◽  
Motor Area ◽  
Oscillatory Activity ◽  
Premotor Area ◽  
Beta Power

Background and Purpose: Cortical beta oscillations are reported to serve as robust measures of the integrity of the human motor system. Their alterations after stroke, such as reduced movement-related beta desynchronization in the primary motor cortex, have been repeatedly related to the level of impairment. However, there is only little data whether such measures of brain function might directly relate to structural brain changes after stroke. Methods: This multimodal study investigated 18 well-recovered patients with stroke (mean age 65 years, 12 males) by means of task-related EEG and diffusion-weighted structural MRI 3 months after stroke. Beta power at rest and movement-related beta desynchronization was assessed in 3 key motor areas of the ipsilesional hemisphere that are the primary motor cortex (M1), the ventral premotor area and the supplementary motor area. Template trajectories of corticospinal tracts (CST) originating from M1, premotor cortex, and supplementary motor area were used to quantify the microstructural state of CST subcomponents. Linear mixed-effects analyses were used to relate tract-related mean fractional anisotropy to EEG measures. Results: In the present cohort, we detected statistically significant reductions in ipsilesional CST fractional anisotropy but no alterations in EEG measures when compared with healthy controls. However, in patients with stroke, there was a significant association between both beta power at rest ( P =0.002) and movement-related beta desynchronization ( P =0.003) in M1 and fractional anisotropy of the CST specifically originating from M1. Similar structure-function relationships were neither evident for ventral premotor area and supplementary motor area, particularly with respect to their CST subcomponents originating from premotor cortex and supplementary motor area, in patients with stroke nor in controls. Conclusions: These data suggest there might be a link connecting microstructure of the CST originating from M1 pyramidal neurons and beta oscillatory activity, measures which have already been related to motor impairment in patients with stroke by previous reports.

scholarly journals The Cortical Motor System in the Domestic Pig: Origin and Termination of the Corticospinal Tract and Cortico-Brainstem Projections

2021 ◽  
Vol 15 ◽  
Author(s):  
Patricia del Cerro ◽  
Ángel Rodríguez-De-Lope ◽  
Jorge E. Collazos-Castro
Keyword(s):  
Spinal Cord ◽  
Motor System ◽  
Primary Motor Cortex ◽  
Corticospinal Tract ◽  
Premotor Cortex ◽  
Mesencephalic Reticular Formation ◽  
Reticular Nucleus ◽  
Descending Pathways ◽  
Spinal Segment ◽  
Cortical Motor

The anatomy of the cortical motor system and its relationship to motor repertoire in artiodactyls is for the most part unknown. We studied the origin and termination of the corticospinal tract (CST) and cortico-brainstem projections in domestic pigs. Pyramidal neurons were retrogradely labeled by injecting aminostilbamidine in the spinal segment C1. After identifying the dual origin of the porcine CST in the primary motor cortex (M1) and premotor cortex (PM), the axons descending from those regions to the spinal cord and brainstem were anterogradely labeled by unilateral injections of dextran alexa-594 in M1 and dextran alexa-488 in PM. Numerous corticospinal projections from M1 and PM were detected up to T6 spinal segment and showed a similar pattern of decussation and distribution in the white matter funiculi and the gray matter laminae. They terminated mostly on dendrites of the lateral intermediate laminae and the internal basilar nucleus, and some innervated the ventromedial laminae, but were essentially absent in lateral laminae IX. Corticofugal axons terminated predominantly ipsilaterally in the midbrain and bilaterally in the medulla oblongata. Most corticorubral projections arose from M1, whereas the mesencephalic reticular formation, superior colliculus, lateral reticular nucleus, gigantocellular reticular nucleus, and raphe received abundant axonal contacts from both M1 and PM. Our data suggest that the porcine cortical motor system has some common features with that of primates and humans and may control posture and movement through parallel motor descending pathways. However, less cortical regions project to the spinal cord in pigs, and the CST neither seems to reach the lumbar enlargement nor to have a significant direct innervation of cervical, foreleg motoneurons.

scholarly journals Changes in corticospinal excitability associated with motor learning by observing

2017 ◽  
Author(s):  
Heather R. McGregor ◽  
Michael Vesia ◽  
Cricia Rinchon ◽  
Robert Chen ◽  
Paul L. Gribble
Keyword(s):  
Motor Learning ◽  
Motor Skills ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Single Pulse ◽  
Abductor Pollicis Brevis ◽  
Functional Changes ◽  
Hand Muscles ◽  
Before And After

AbstractWhile many of our motor skills are acquired through physical practice, we can also learn how to make movements by observing others. For example, individuals can learn how to reach in novel dynamical environments (‘force fields’, FF) by observing the movements of a tutor. Previous neurophysiology and neuroimaging studies in humans suggest a role for the motor system in motor learning by observing. Here we tested the role of primary motor cortex (M1) in motor learning by observing. We used single-pulse transcranial magnetic stimulation (TMS) to elicit motor evoked potentials (MEPs) in right hand muscles at rest. MEPs were elicited before and after participants observed either a video adapting her reaches to a FF or a control video showing a tutor performing reaches in an unlearnable FF. We predicted that observing motor learning would increase M1 excitability to a greater extent than observing movements that did not involve learning. We found that observing FF learning increased MEP amplitudes recorded from right first dorsal interosseous (FDI) and right abductor pollicis brevis (APB) muscles. There were no changes in MEP amplitudes for control participants who observed a tutor performing reaches in an unlearnable, randomly varying FF. The observed MEP changes can thus be specifically linked to observing motor learning. These results are consistent with the idea that observing motor learning produces functional changes in M1, or corticospinal networks or both.

scholarly journals Increasing and decreasing interregional brain coupling increases and decreases oscillatory activity in the human brain

2021 ◽  
Vol 118 (37) ◽  
pp. e2100652118
Author(s):  
Alejandra Sel ◽  
Lennart Verhagen ◽  
Katharina Angerer ◽  
Raluca David ◽  
Miriam C. Klein-Flügge ◽  
...  
Keyword(s):  
Human Brain ◽  
Alpha Rhythm ◽  
Primary Motor Cortex ◽  
Premotor Cortex ◽  
Motor Task ◽  
Brain Regions ◽  
Spike Timing ◽  
Oscillatory Activity ◽  
The Impact ◽  
The Brain

The origins of oscillatory activity in the brain are currently debated, but common to many hypotheses is the notion that they reflect interactions between brain areas. Here, we examine this possibility by manipulating the strength of coupling between two human brain regions, ventral premotor cortex (PMv) and primary motor cortex (M1), and examine the impact on oscillatory activity in the motor system measurable in the electroencephalogram. We either increased or decreased the strength of coupling while holding the impact on each component area in the pathway constant. This was achieved by stimulating PMv and M1 with paired pulses of transcranial magnetic stimulation using two different patterns, only one of which increases the influence exerted by PMv over M1. While the stimulation protocols differed in their temporal patterning, they were comprised of identical numbers of pulses to M1 and PMv. We measured the impact on activity in alpha, beta, and theta bands during a motor task in which participants either made a preprepared action (Go) or withheld it (No-Go). Augmenting cortical connectivity between PMv and M1, by evoking synchronous pre- and postsynaptic activity in the PMv–M1 pathway, enhanced oscillatory beta and theta rhythms in Go and No-Go trials, respectively. Little change was observed in the alpha rhythm. By contrast, diminishing the influence of PMv over M1 decreased oscillatory beta and theta rhythms in Go and No-Go trials, respectively. This suggests that corticocortical communication frequencies in the PMv–M1 pathway can be manipulated following Hebbian spike-timing–dependent plasticity.

scholarly journals Sensory and auditory evoked responses mimic synchronization of cortical oscillations induced by Transcranial Magnetic Stimulation

2019 ◽  
Author(s):  
Lutz A. Krawinkel ◽  
Julia Forisch ◽  
Jan F. Feldheim ◽  
Winifried Backhaus ◽  
Fanny Quandt ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Phase Synchronization ◽  
Premotor Cortex ◽  
Oscillatory Activity ◽  
Phase Lag ◽  
Somatosensory Stimulation ◽  
Close Vicinity ◽  
Cortical Oscillations

AbstractBackgroundEntrainment of cortical oscillations by repetitive Transcranial Magnetic Stimulation (rTMS) is an attractive approach to modulate brain function non-invasively in humans. Here, we applied rTMS in order to modulate oscillatory activity in ventral premotor cortex (PMv), primary motor cortex (M1), and anterior intraparietal sulcus (aIPS). These areas are thought to contribute to recovery after motor stroke and our overarching goal is to enhance their impact by rTMS. To this end, we established a setup with bifocal, neuronavigated rTMS combined with EEG and tested its technical feasibility.MethodsBifocal zero-phase lag synchronized rTMS at 11Hz was applied in seven young healthy volunteers to the target pairs (i) PMv and M1 and (ii) aIPS and M1. Adapting to the close vicinity between target areas, we used two small, commercially available coils and applied subthreshold stimuli in order to avoid motor evoked potentials (MEPs). Besides a parieto-occipital sham stimulation, we also included auditory and sensory stimulation in a further control experiment.ResultsFirst, subthreshold TMS led to a phase synchronization and evoked time-averaged potentials in the EEG. However, the same findings could be elicited by peripheral, somatosensory stimulation combined with auditory stimulation. Second, despite the small coils neuronavigation analysis showed that in most participants aIPS and M1 or PMv and M1 could not precisely be targeted due to their vicinity and restriction in coil positioning. Third, bifocal subthreshold rTMS tended to sum up where the induced fields showed the greatest overlap resulting in overt MEPs and thus raising potential safety issues.ConclusionsThe presented data show refinements for bifocal rTMS studies regarding (i) spurious entrainment or resetting effects on brain oscillations, (ii) precise anatomical targeting of areas in close vicinity, and (iii) summing up of overlapping induced electrical fields.

scholarly journals Retrospective Exploratory Analysis of Task-Specific Effects on Brain Activity after Stroke

2021 ◽  
Author(s):  
Marika Demers ◽  
Rini Varghese ◽  
Carolee J Winstein
Keyword(s):  
Primary Motor Cortex ◽  
Brain Activity ◽  
Premotor Cortex ◽  
Chronic Stroke ◽  
Exploratory Analysis ◽  
Cortical Reorganization ◽  
Control Group ◽  
Stroke Survivors ◽  
Task Specificity ◽  
Before And After

Background: Evidence supports cortical reorganization in sensorimotor areas induced by constraint-induced movement therapy (CIMT). However, only a few studies examined the neural plastic changes as a function of task specificity. This provoked us to retrospectively analyze a previously unpublished imaging dataset from chronic stroke survivors before and after participation in the signature CIMT protocol. This exploratory analysis aims to evaluate the functional brain activation changes during a precision and a power grasp task in chronic stroke survivors who received two-weeks of CIMT compared to a control group. Materials and methods: Fourteen chronic stroke survivors, randomized to CIMT (n=8) or non-CIMT (n=6), underwent functional MRI (fMRI) before and after a two-week period. During scan runs, participants performed two different grasp tasks (precision, power). Pre to post changes in laterality index (LI) were compared by group and task for two predetermined motor regions of interest: dorsal premotor cortex (PMd) and primary motor cortex (MI). Results: Two weeks of CIMT resulted in a relative increase in activity in a key region of the motor network, the PMd of the lesioned hemisphere, under precision grasp task conditions compared to a non-treatment control group. However, no changes in LI were observed in MI for either task or group. Conclusion: These findings provide evidence for the task specificity effects of CIMT in the promotion of recovery-supportive cortical reorganization in chronic stroke survivors.

The frontal longitudinal system as revealed through the fiber microdissection technique: structural evidence underpinning the direct connectivity of the prefrontal-premotor circuitry

2020 ◽  
Vol 133 (5) ◽  
pp. 1503-1515 ◽  
Author(s):  
Spyridon Komaitis ◽  
Aristotelis V. Kalyvas ◽  
Georgios P. Skandalakis ◽  
Evangelos Drosos ◽  
Evgenia Lani ◽  
...  
Keyword(s):  
Primary Motor Cortex ◽  
Premotor Cortex ◽  
Frontal Area ◽  
Frontal Pole ◽  
Fiber System ◽  
Dorsolateral Prefrontal ◽  
Anterior Extension ◽  
Brodmann Areas ◽  
Longitudinal Fiber ◽  
Long Fibers

OBJECTIVEThe purpose of this study was to investigate the morphology, connectivity, and correlative anatomy of the longitudinal group of fibers residing in the frontal area, which resemble the anterior extension of the superior longitudinal fasciculus (SLF) and were previously described as the frontal longitudinal system (FLS).METHODSFifteen normal adult formalin-fixed cerebral hemispheres collected from cadavers were studied using the Klingler microdissection technique. Lateral to medial dissections were performed in a stepwise fashion starting from the frontal area and extending to the temporoparietal regions.RESULTSThe FLS was consistently identified as a fiber pathway residing just under the superficial U-fibers of the middle frontal gyrus or middle frontal sulcus (when present) and extending as far as the frontal pole. The authors were able to record two different configurations: one consisting of two distinct, parallel, longitudinal fiber chains (13% of cases), and the other consisting of a single stem of fibers (87% of cases). The fiber chains’ cortical terminations in the frontal and prefrontal area were also traced. More specifically, the FLS was always recorded to terminate in Brodmann areas 6, 46, 45, and 10 (premotor cortex, dorsolateral prefrontal cortex, pars triangularis, and frontal pole, respectively), whereas terminations in Brodmann areas 4 (primary motor cortex), 47 (pars orbitalis), and 9 were also encountered in some specimens. In relation to the SLF system, the FLS represented its anterior continuation in the majority of the hemispheres, whereas in a few cases it was recorded as a completely distinct tract. Interestingly, the FLS comprised shorter fibers that were recorded to interconnect exclusively frontal areas, thus exhibiting different fiber architecture when compared to the long fibers forming the SLF.CONCLUSIONSThe current study provides consistent, focused, and robust evidence on the morphology, architecture, and correlative anatomy of the FLS. This fiber system participates in the axonal connectivity of the prefrontal-premotor cortices and allegedly subserves cognitive-motor functions. Based in the SLF hypersegmentation concept that has been advocated by previous authors, the FLS should be approached as a distinct frontal segment within the superior longitudinal system.

scholarly journals Fecal Metaproteomics Reveals Reduced Gut Inflammation and Changed Microbial Metabolism Following Lifestyle-Induced Weight Loss

Biomolecules ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 726
Author(s):  
Ronald Biemann ◽  
Enrico Buß ◽  
Dirk Benndorf ◽  
Theresa Lehmann ◽  
Kay Schallert ◽  
...  
Keyword(s):  
Metabolic Syndrome ◽  
Weight Loss ◽  
Gut Microbiome ◽  
Taxonomic Composition ◽  
Low Grade ◽  
Gut Inflammation ◽  
Functional Changes ◽  
Microbiome Composition ◽  
Before And After ◽  
Human Proteins

Gut microbiota-mediated inflammation promotes obesity-associated low-grade inflammation, which represents a hallmark of metabolic syndrome. To investigate if lifestyle-induced weight loss (WL) may modulate the gut microbiome composition and its interaction with the host on a functional level, we analyzed the fecal metaproteome of 33 individuals with metabolic syndrome in a longitudinal study before and after lifestyle-induced WL in a well-defined cohort. The 6-month WL intervention resulted in reduced BMI (−13.7%), improved insulin sensitivity (HOMA-IR, −46.1%), and reduced levels of circulating hsCRP (−39.9%), indicating metabolic syndrome reversal. The metaprotein spectra revealed a decrease of human proteins associated with gut inflammation. Taxonomic analysis revealed only minor changes in the bacterial composition with an increase of the families Desulfovibrionaceae, Leptospiraceae, Syntrophomonadaceae, Thermotogaceae and Verrucomicrobiaceae. Yet we detected an increased abundance of microbial metaprotein spectra that suggest an enhanced hydrolysis of complex carbohydrates. Hence, lifestyle-induced WL was associated with reduced gut inflammation and functional changes of human and microbial enzymes for carbohydrate hydrolysis while the taxonomic composition of the gut microbiome remained almost stable. The metaproteomics workflow has proven to be a suitable method for monitoring inflammatory changes in the fecal metaproteome.

scholarly journals Hippocampus-retrosplenial cortex interaction is increased during phasic REM and contributes to memory consolidation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Daniel Gomes de Almeida-Filho ◽  
Bruna Del Vechio Koike ◽  
Francesca Billwiller ◽  
Kelly Soares Farias ◽  
Igor Rafael Praxedes de Sales ◽  
...  
Keyword(s):  
Rem Sleep ◽  
Memory Consolidation ◽  
Retrosplenial Cortex ◽  
Contextual Fear Conditioning ◽  
Oscillatory Activity ◽  
Theta Oscillation ◽  
Contextual Fear ◽  
Before And After ◽  
Freely Behaving ◽  
Phasic Rem Sleep

AbstractHippocampal (HPC) theta oscillation during post-training rapid eye movement (REM) sleep supports spatial learning. Theta also modulates neuronal and oscillatory activity in the retrosplenial cortex (RSC) during REM sleep. To investigate the relevance of theta-driven interaction between these two regions to memory consolidation, we computed the Granger causality within theta range on electrophysiological data recorded in freely behaving rats during REM sleep, both before and after contextual fear conditioning. We found a training-induced modulation of causality between HPC and RSC that was correlated with memory retrieval 24 h later. Retrieval was proportional to the change in the relative influence RSC exerted upon HPC theta oscillation. Importantly, causality peaked during theta acceleration, in synchrony with phasic REM sleep. Altogether, these results support a role for phasic REM sleep in hippocampo-cortical memory consolidation and suggest that causality modulation between RSC and HPC during REM sleep plays a functional role in that phenomenon.

scholarly journals Cerebellar rTMS and PAS effectively induce cerebellar plasticity

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Martje G. Pauly ◽  
Annika Steinmeier ◽  
Christina Bolte ◽  
Feline Hamami ◽  
Elinor Tzvi ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Healthy Subjects ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Premotor Cortex ◽  
Motor Pathways ◽  
Non Invasive ◽  
Cerebellar Plasticity

AbstractNon-invasive brain stimulation techniques including repetitive transcranial magnetic stimulation (rTMS), continuous theta-burst stimulation (cTBS), paired associative stimulation (PAS), and transcranial direct current stimulation (tDCS) have been applied over the cerebellum to induce plasticity and gain insights into the interaction of the cerebellum with neo-cortical structures including the motor cortex. We compared the effects of 1 Hz rTMS, cTBS, PAS and tDCS given over the cerebellum on motor cortical excitability and interactions between the cerebellum and dorsal premotor cortex / primary motor cortex in two within subject designs in healthy controls. In experiment 1, rTMS, cTBS, PAS, and tDCS were applied over the cerebellum in 20 healthy subjects. In experiment 2, rTMS and PAS were compared to sham conditions in another group of 20 healthy subjects. In experiment 1, PAS reduced cortical excitability determined by motor evoked potentials (MEP) amplitudes, whereas rTMS increased motor thresholds and facilitated dorsal premotor-motor and cerebellum-motor cortex interactions. TDCS and cTBS had no significant effects. In experiment 2, MEP amplitudes increased after rTMS and motor thresholds following PAS. Analysis of all participants who received rTMS and PAS showed that MEP amplitudes were reduced after PAS and increased following rTMS. rTMS also caused facilitation of dorsal premotor-motor cortex and cerebellum-motor cortex interactions. In summary, cerebellar 1 Hz rTMS and PAS can effectively induce plasticity in cerebello-(premotor)-motor pathways provided larger samples are studied.

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