scholarly journals Transient beta activity and connectivity during sustained motor behaviour

2021 ◽  
Author(s):  
Irene Echeverria-Altuna ◽  
Andrew J. Quinn ◽  
Nahid Zokaei ◽  
Mark W. Woolrich ◽  
Anna C. Nobre ◽  
...  
Keyword(s):  
Long Range ◽  
Isometric Contraction ◽  
Task Demands ◽  
Beta Activity ◽  
List Type ◽  
Motor Behaviour ◽  
Event Duration ◽  
The Status ◽  
Human Participants ◽  
The Brain

AbstractNeural oscillations are thought to play a central role in orchestrating activity states between distant neural populations. In humans, long-range neural connectivity has been particularly well characterised for 13-30 Hz beta activity which becomes phase coupled between the motor cortex and the contralateral muscle during isometric contraction. Based on this and related observations, beta activity and connectivity have been linked to sustaining stable cognitive and motor states – or the ‘status quo’ – in the brain. Recently, however, beta activity has been shown to be short-lived, as opposed to sustained – though so far this has been reported for regional beta activity in tasks without sustained motor demands. Here, we measured magnetoencephalography (MEG) and electromyography (EMG) in 18 human participants performing an isometric-contraction (gripping) task designed to yield sustained behavioural output. If cortico-muscular beta connectivity is directly responsible for sustaining a stable motor state, then beta activity should be (or become) sustained in this context. In contrast, we found that beta activity and connectivity with the downstream muscle were transient, even when participants engaged in sustained gripping. Moreover, we found that sustained motor requirements did not prolong beta-event duration in comparison to rest. These findings suggest that long-range neural synchronisation may entail short ‘bursts’ of frequency-specific connectivity, even when task demands – and behaviour – are sustained.HighlightsTrial-average 13-30 Hz beta activity and connectivity with the muscle appear sustained during stable motor behaviourSingle-trial beta activity and connectivity are short-lived, even when motor behaviour is sustainedSustained task demands do not prolong beta-event duration in comparison to resting state

scholarly journals Neural oscillations track the maintenance and proceduralization of novel instructions

2020 ◽  
Author(s):  
Silvia Formica ◽  
Carlos González-García ◽  
Mehdi Senoussi ◽  
Marcel Brass
Keyword(s):  
Cognitive Processes ◽  
Theoretical Models ◽  
Beta Activity ◽  
List Type ◽  
Attentional Orienting ◽  
Time Frequency ◽  
Attentional Deployment ◽  
Component Processes ◽  
Motor Recruitment ◽  
The Brain

AbstractHumans are capable of flexibly converting symbolic instructions into novel behaviors. Previous evidence and theoretical models suggest that the implementation of a novel instruction requires the reformatting of its declarative content into an action-oriented code optimized for the execution of the instructed behavior. While neuroimaging research focused on identifying the brain areas involved in such a process, the temporal and electrophysiological mechanisms remain poorly understood. These mechanisms, however, can provide information about the specific cognitive processes that characterize the proceduralization of information. In the present study, we recorded EEG activity while we asked participants to either simply maintain declaratively the content of novel S-R mappings or to proactively prepare for their implementation. By means of time-frequency analyses, we isolated the oscillatory features specific to the proceduralization of instructions. Implementation of the instructed mappings elicited stronger theta activity over frontal electrodes and suppression in mu and beta activity over central electrodes. On the contrary, activity in the alpha band, which has been shown to track the attentional deployment to task-relevant items, showed no differences between tasks. Together, these results support the idea that proceduralization of information is characterized by specific component processes such as orchestrating complex task settings and configuring the motor system that are not observed when instructions are held in a declarative format.HighlightsFrontal theta power is increased during instructions implementationAttentional orienting in WM is analogous across maintenance and implementationInstructions implementation involves motor recruitment

scholarly journals Interhemispheric Binding of Ambiguous Visual Motion Is Associated with Changes in Beta Oscillatory Activity but Not with Gamma Range Synchrony

2017 ◽  
Vol 29 (11) ◽  
pp. 1829-1844 ◽  
Author(s):  
Gabriel Nascimento Costa ◽  
João Valente Duarte ◽  
Ricardo Martins ◽  
Michael Wibral ◽  
Miguel Castelo-Branco
Keyword(s):  
Long Range ◽  
Large Scale ◽  
Visual Motion ◽  
Oscillatory Activity ◽  
Beta Activity ◽  
Binding Problem ◽  
Gamma Range ◽  
Beta Power ◽  
Gamma Synchrony ◽  
The Brain

In vision, perceptual features are processed in several regions distributed across the brain. Yet, the brain achieves a coherent perception of visual scenes and objects through integration of these features, which are encoded in spatially segregated brain areas. How the brain seamlessly achieves this accurate integration is currently unknown and is referred to as the “binding problem.” Among the proposed mechanisms meant to resolve the binding problem, the binding-by-synchrony hypothesis proposes that binding is carried out by the synchronization of distant neuronal assemblies. This study aimed at providing a critical test to the binding-by-synchrony hypothesis by evaluating long-range connectivity using EEG during a motion integration visual task that entails binding across hemispheres. Our results show that large-scale perceptual binding is not associated with long-range interhemispheric gamma synchrony. However, distinct perceptual interpretations were found to correlate with changes in beta power. Increased beta activity was observed during binding under ambiguous conditions and originates mainly from parietal regions. These findings reveal that the visual experience of binding can be identified by distinct signatures of oscillatory activity, regardless of long-range gamma synchrony, suggesting that such type of synchrony does not underlie perceptual binding.

scholarly journals Sparse long-range connections in visual cortex for cost-efficient small-world networks

2020 ◽  
Author(s):  
Seungdae Baek ◽  
Youngjin Park ◽  
Se-Bum Paik
Keyword(s):  
Neural Networks ◽  
Visual Cortex ◽  
Object Recognition ◽  
Long Range ◽  
Deep Neural Networks ◽  
Small World ◽  
List Type ◽  
Cost Efficient ◽  
Local Circuits ◽  
The Brain

AbstractThe brain performs visual object recognition using much shallower hierarchical stages than artificial deep neural networks employ. However, the mechanism underlying this cost-efficient function is elusive. Here, we show that cortical long-range connectivity(LRC) may enable this parsimonious organization of circuits for balancing cost and performance. Using model network simulations based on data in tree shrews, we found that sparse LRCs, when added to local connections, organize a small-world network that dramatically enhances object recognition of shallow feedforward networks. We found that optimization of the ratio between LRCs and local connections maximizes the small-worldness and task performance of the network, by minimizing the total length of wiring needed for integration of the global information. We also found that the effect of LRCs varies by network size, which explains the existence of species-specific LRCs in mammalian visual cortex of various sizes. Our results demonstrate a biological strategy to achieve cost-efficient brain circuits.HighlightsLong-range connections (LRCs) enhance the object recognition of shallow networksSparse LRCs added to dense local connections organize a small-world type networkSmall-worldness of networks modulates the balance between performance and wiring costDistinct LRCs in various species are due to the size-dependent effect of LRCsSignificance statementThe hierarchical depth of the visual pathway in the brain is constrained by biological factors, whereas artificial deep neural networks consist of super-deep structures (i.e., as deep as computational power allows). Here, we show that long-range horizontal connections (LRCs) observed in mammalian visual cortex may enable shallow biological networks to perform cognitive tasks that require deeper artificial structures, by implementing cost-efficient organization of circuitry. Using model simulations based on anatomical data, we found that sparse LRCs, when added to dense local circuits, organize “small-world” type networks and that this dramatically enhances image classification performance by integrating both local and global components of visual stimulus. Our findings show a biological strategy of brain circuitry to balance sensory performance and wiring cost in the networks.One sentence summaryCortical long-range connections organize a small-world type network to achieve cost-efficient functional circuits under biological constraints

scholarly journals A novel PET tracer 18F-deoxy-thiamine: synthesis, metabolic kinetics, and evaluation on cerebral thiamine metabolism status

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Changpeng Wang ◽  
Siwei Zhang ◽  
Yuefei Zou ◽  
Hongzhao Ma ◽  
Donglang Jiang ◽  
...  
Keyword(s):  
High Performance ◽  
Specific Activity ◽  
High Accumulation ◽  
Metabolic Kinetics ◽  
Thiamine Metabolism ◽  
Pet Tracer ◽  
The Status ◽  
The Brain

Abstract Background Some neuropsychological diseases are associated with abnormal thiamine metabolism, including Korsakoff–Wernicke syndrome and Alzheimer’s disease. However, in vivo detection of the status of brain thiamine metabolism is still unavailable and needs to be developed. Methods A novel PET tracer of 18F-deoxy-thiamine was synthesized using an automated module via a two-step route. The main quality control parameters, such as specific activity and radiochemical purity, were evaluated by high-performance liquid chromatography (HPLC). Radiochemical concentration was determined by radioactivity calibrator. Metabolic kinetics and the level of 18F-deoxy-thiamine in brains of mice and marmosets were studied by micro-positron emission tomography/computed tomography (PET/CT). In vivo stability, renal excretion rate, and biodistribution of 18F-deoxy-thiamine in the mice were assayed using HPLC and γ-counter, respectively. Also, the correlation between the retention of cerebral 18F-deoxy-thiamine in 60 min after injection as represented by the area under the curve (AUC) and blood thiamine levels was investigated. Results The 18F-deoxy-thiamine was stable both in vitro and in vivo. The uptake and clearance of 18F-deoxy-thiamine were quick in the mice. It reached the max standard uptake value (SUVmax) of 4.61 ± 0.53 in the liver within 1 min, 18.67 ± 7.04 in the kidney within half a minute. The SUV dropped to 0.72 ± 0.05 and 0.77 ± 0.35 after 60 min of injection in the liver and kidney, respectively. After injection, kidney, liver, and pancreas exhibited high accumulation level of 18F-deoxy-thiamine, while brain, muscle, fat, and gonad showed low accumulation concentration, consistent with previous reports on thiamine distribution in mice. Within 90 min after injection, the level of 18F-deoxy-thiamine in the brain of C57BL/6 mice with thiamine deficiency (TD) was 1.9 times higher than that in control mice, and was 3.1 times higher in ICR mice with TD than that in control mice. The AUC of the tracer in the brain of marmosets within 60 min was 29.33 ± 5.15 and negatively correlated with blood thiamine diphosphate levels (r = − 0.985, p = 0.015). Conclusion The 18F-deoxy-thiamine meets the requirements for ideal PET tracer for in vivo detecting the status of cerebral thiamine metabolism.

scholarly journals Human low-threshold mechanoafferent responses to pure changes in friction controlled using an ultrasonic haptic device

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mariama Dione ◽  
Roger Holmes Watkins ◽  
Eric Vezzoli ◽  
Betty Lemaire-Semail ◽  
Johan Wessberg
Keyword(s):  
Central Nervous System ◽  
Stable Phase ◽  
Sensory Cues ◽  
Temporal Precision ◽  
Object Interaction ◽  
Tactile Stimulator ◽  
The Status ◽  
The Central Nervous System ◽  
Low Threshold ◽  
Human Participants

AbstractThe forces that are developed when manipulating objects generate sensory cues that inform the central nervous system about the qualities of the object’s surface and the status of the hand/object interaction. Afferent responses to frictional transients or slips have been studied in the context of lifting/holding tasks. Here, we used microneurography and an innovative tactile stimulator, the Stimtac, to modulate both the friction level of a surface, without changing the surface or adding a lubricant, and, to generate the frictional transients in a pure and net fashion. In three protocols, we manipulated: the frictional transients, the friction levels, the rise times, the alternation of phases of decrease or increase in friction to emulate grating-like stimuli. Afferent responses were recorded in 2 FAIs, 1 FAII, 2 SAIs and 3 SAIIs from the median nerve of human participants. Independently of the unit type, we observed that: single spikes were generated time-locked to the frictional transients, and that reducing the friction level reduced the number of spikes during the stable phase of the stimulation. Our results suggest that those frictional cues are encoded in all the unit types and emphasize the possibility to use the Stimtac device to control mechanoreceptor firing with high temporal precision.

FC29-02 - Is prenatal exposure to alcohol a factor which re-program the brain?

2011 ◽  
Vol 26 (S2) ◽  
pp. 1978-1978
Author(s):  
J.H. Sliwowska
Keyword(s):  
Prenatal Exposure ◽  
Hpa Axis ◽  
Alcohol Exposure ◽  
Hippocampal Neurogenesis ◽  
Adult Hippocampal Neurogenesis ◽  
Ovariectomized Rats ◽  
List Type ◽  
Depression And Anxiety ◽  
Hpg Axis ◽  
The Brain

IntroductionFetal programming refers to the concept that early environmental factors, including prenatal exposure to stress and drugs, can permanently organize or imprint physiological and behavioural systems and increase vulnerability to disorders such as depression and anxiety later in life.AimsIs prenatal exposure to alcohol a factor which re-programs the brain?ObjectivesEffects of prenatal alcohol exposure (PAE) on:1)the hypothalamus-pituitary-adrenal (HPA) axis;2)the hypothalamus-pituitary-gonadal (HPG) axis;3)serotonergic (5-HT) system and4)adult hippocampal neurogenesis are presented.MethodsOffspring from prenatal ethanol (PAE), pair-fed (PF) and ad lib-fed control (C) dams are studied across the development or in adulthood. Immunocytochemistry and in situ hybridization techniques are used.ResultsIn term of the HPA axis: PAE alters the balance of mineralocorticoids/glucocorticoids (MRs/GRs) receptor levels in the hippocampus of adult females. In the case of the HPG axis: PAE delays puberty and changes hormonal profiles in males and females. PAE also decreases numbers of 5-HT-immunoreactive neurons in the dorsal raphe nucleus of the brainstem in ovariectomized rats and estradiol and progesterone modulate those effects. Finally, in adult PAE males, but not females stress-induced decrease in neurogenesis is altered.ConclusionsIn our animal model PAE re-programs the brain. Effects of PAE are long-lasting, affect HPA and HPG axes, 5-HT system and adult hippocampal neurogenesis and if seen in humans could contribute to increased vulnerability to depression and anxiety.

Frontal lobes and attention: Processes and networks, fractionation and integration

2006 ◽  
Vol 12 (2) ◽  
pp. 261-271 ◽  
Author(s):  
DONALD T. STUSS
Keyword(s):  
Frontal Lobes ◽  
Task Demands ◽  
Activation Process ◽  
Top Down ◽  
Supervisory System ◽  
Current Task ◽  
Frontal Processes ◽  
General Activation ◽  
Lesion Studies ◽  
The Brain

The frontal lobes (FL), are they a general adaptive global capacity processor, or a series of fractionated processes? Our lesion studies focusing on attention have demonstrated impairments in distinct processes due to pathology in different frontal regions, implying fractionation of the “supervisory system.” However, when task demands are manipulated, it becomes evident that the frontal lobes are not just a series of independent processes. Increased complexity of task demands elicits greater involvement of frontal regions along a fixed network related to a general activation process. For some task demands, one or more anatomically distinct frontal processes may be recruited. In other conditions, there is a bottom-up nonfrontal/frontal network, with impairment noted maximally for the lesser task demands in the nonfrontal automatic processing regions, and then as task demands change, increased involvement of different frontal (more “strategic”) regions, until it appears all frontal regions are involved. With other measures, the network is top-down, with impairment in the measure first noted in the frontal region and then, with changing task demands, involving a posterior region. Adaptability is not just a property of FL, it is the fluid recruitment of different processes anywhere in the brain as required by the current task. (JINS, 2006,12, 261–271.)

BIOELECTRIC ACTIVITY OF THE BRAIN IN PATIENTS WITH ACUTE CEREBROVASCULAR ACCIDENT

Vestnik ◽  
2021 ◽  
pp. 29-34
Author(s):  
Д.А. Митрохин ◽  
М.М. Ибрагимов ◽  
Б.Р. Нурмухамбетова ◽  
Н.Ш. Буйракулова ◽  
В.В. Харченко ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Hemorrhagic Stroke ◽  
Spectral Power ◽  
Spectral Power Density ◽  
Cerebral Stroke ◽  
Beta Activity ◽  
Bioelectric Activity ◽  
Early Recovery ◽  
Coherence Index ◽  
The Brain

Значимость биоэлектрической активности головного мозга в оценке функционального состояния нервной системы при цереброваскулярных заболеваниях широко известна. В настоящей работе показана характеристика биоэлектрической активности головного мозга у больных, перенесших острое нарушение мозгового кровообращения. В данной статье приведены данные о том, что у больных в остром и раннем восстановительном периодах церебрального инсульта биоэлектрическая активность головного мозга характеризовалась, в основном, десинхронным и дезорганизованным типами электроэнцефалограммы. Вместе с тем, отмечались, выраженная дельта и тета активность, а также единичные острые волны, спайки, преимущественно в пораженном полушарии головного мозга, реже в контралатеральном полушарии, межполушарная асимметрия, повышение мощности спектров в сторону преобладания медленных волн. Показатели индекса когерентности по всем отведениям были снижены, что свидетельствует о нарушении функциональных межполушарных взаимосвязей. Более значительное повышение индекса когерентности в дельта и тета диапазонах у пациентов, перенесших геморрагический инсульт, может указывать на более грубые межполушарные нарушения, в сравнении с ишемическим инсультом. Результаты исследования относительной спектральной плотности мощности диапазонов показали, что при геморрагическом инсульте отмечена более высокая дельта и бета активность, а также более значительное снижение мощности альфа ритма, в сравнении с ишемическим инсультом. В тоже время, отмечается повышение интегрального индекса диапазона низкочастотной медленно-волновой активности, особенно выраженное у больных с геморрагическим инсультом р<0,05. The significance of bioelectric activity of the brain in assessing the functional state of the nervous system in cerebrovascular diseases is widely known. In this paper, the characteristics of the bioelectric activity of the brain in patients with acute cerebral circulatory disorders are shown. This article presents data that in patients with acute and early recovery periods of cerebral stroke , the bioelectric activity of the brain was characterized mainly by desynchronous and disorganized types of electroencephalogram. At the, same time, pronounced delta and theta activity was noted , as well as single acute waves, spikes, mainly in the affected hemisphere of the brain, less often in the contralateral hemisphere, interhemispheric asymmetry, increased spectral power in the direction of predominance of slow waves. The coherence index values for all leads were reduced, which indicates a violation of functional interhemispheric relationships. A more significant increase in the coherence index in the delta and theta ranges in patients who have had a hemorrhagic stroke may indicate more severe interhemispheric disorders compared to ischemic stroke. The results of the study of the relative spectral power density of the ranges showed, that in hemorrhagic stroke, there was a higher delta and beta activity, as well as a more significant decrease in the power of the alpha rhythm, in comparison with ischemic stroke. At the same time, there is an increase in the integral index of the range of low-frequency slow-wave activity, especially pronounced in patients with hemorrhagic stroke p < 0.05.

Psychiatry, folk psychology, and the impact of neuroscience—a response to Steven Hyman’s Loebel Lectures

2020 ◽  
pp. 304-319
Author(s):  
Jonathan Glover
Keyword(s):  
Fine Structure ◽  
Psychiatric Disorders ◽  
Folk Psychology ◽  
The Status ◽  
The Impact ◽  
The Brain

This chapter reflects on Steven Hyman's Loebel Lectures, which revolve around a contrast between folk psychology and what neuroscience is starting to reveal. Folk psychology is the unscientific picture of what goes on in people’s minds when they perceive, remember, think, feel, decide, and act. It is based on introspection and on intuitive ‘reading’ of other people. In contrast to folk psychology is the fine structure neuroscience is starting to reveal: the brain mechanisms underlying perception, memory, thought, emotion, decision, and action. Hyman says that mapping out this fine structure has the promise of changing the understanding and treatment of psychiatric disorders. Out of this emerges Hyman’s philosophical claim that neuroscience radically challenges the status of folk psychology. Folk psychology, being in conflict with neuroscience, is largely false.

scholarly journals Influence of a nonforage diet on plasma leptin in dairy goats throughout lactation

2002 ◽  
Vol 2002 ◽  
pp. 97-97
Author(s):  
F. Rosi ◽  
L. Rapetti
Keyword(s):  
Energy Homeostasis ◽  
Peptide Hormone ◽  
Dairy Goats ◽  
Lactating Goats ◽  
Energy Stores ◽  
The Status ◽  
Plasma Leptin ◽  
Body Energy ◽  
The Brain ◽  
By Products

Leptin is a 16kDa peptide hormone mainly secreted by fat cells to regulate of food intake and energy homeostasis, and to signal the status of body energy stores to the brain (Houseknecht et al., 1998). In ruminant, reducing feedstuffs particle size increases DM intake, particularly if feedstuffs quality is poor, due to a shorter retention time of the particles in the rumen. By-products are included in the ration to supply energy and protein, but they have often a high content of fibre. The by-product fibre has different properties than forage NDF, being characterised by particles of small dimensions and a high density. The aim of this study was to compare the plasma level of leptin in lactating goats fed a traditional silage-based diet or a totally free forage diet, throughout lactation and during the pre and post-feeding state.

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