LFP beta amplitude is predictive of mesoscopic spatio-temporal phase patterns

Beta oscillations observed in motor cortical local field potentials (LFPs) recorded on separate electrodes of a multi-electrode array have been shown to exhibit non-zero phase shifts that organize into a planar wave propagation. Here, we generalize this concept by introducing additional classes of patterns that fully describe the spatial organization of beta oscillations. During a delayed reach-to-grasp task in monkey primary motor and dorsal premotor cortices we distinguish planar, synchronized, random, circular, and radial phase patterns. We observe that specific patterns correlate with the beta amplitude (envelope). In particular, wave propagation accelerates with growing amplitude, and culminates at maximum amplitude in a synchronized pattern. Furthermore, the occurrence probability of a particular pattern is modulated with behavioral epochs: Planar waves and synchronized patterns are more present during movement preparation where beta amplitudes are large, whereas random phase patterns are dominant during movement execution where beta amplitudes are small

VIOLA - A multi-purpose and web-based visualization tool for neuronal-network simulation output

Neuronal network models and corresponding computer simulations are invaluable tools to aid the interpretation of the relationship between neuron properties, connectivity and measured activity in cortical tissue. Spatiotemporal patterns of activity propagating across the cortical surface as observed experimentally can for example be described by neuronal network models with layered geometry and distance-dependent connectivity. The interpretation of the resulting stream of multi-modal and multi-dimensional simulation data calls for integrating interactive visualization steps into existing simulation-analysis workflows. Here, we present a set of interactive visualization concepts called views for the visual analysis of activity data in topological network models, and a corresponding reference implementation VIOLA (VIsualization Of Layer Activity). The software is a lightweight, open-source, web-based and platform-independent application combining and adapting modern interactive visualization paradigms, such as coordinated multiple views, for massively parallel neurophysiological data. For a use-case demonstration we consider spiking activity data of a two-population, layered point-neuron network model subject to a spatially confined excitation originating from an external population. With the multiple coordinated views, an explorative and qualitative assessment of the spatiotemporal features of neuronal activity can be performed upfront of a detailed quantitative data analysis of specific aspects of the data. Furthermore, ongoing efforts including the European Human Brain Project aim at providing online user portals for integrated model development, simulation, analysis and provenance tracking, wherein interactive visual analysis tools are one component. Browser-compatible, web-technology based solutions are therefore required. Within this scope, with VIOLA we provide a first prototype.Comment: 38 pages, 10 figures, 3 table

Behavioral Context Determines Network State and Variability Dynamics in Monkey Motor Cortex

Variability of spiking activity is ubiquitous throughout the brain but little is known about its contextual dependance. Trial-to-trial spike count variability, estimated by the Fano Factor (FF), and within-trial spike time irregularity, quantified by the coefficient of variation (CV), reflect variability on long and short time scales, respectively. We co-analyzed FF and the local coefficient of variation (CV2) in monkey motor cortex comparing two behavioral contexts, movement preparation (wait) and execution (movement). We find that the FF significantly decreases from wait to movement, while the CV2 increases. The more regular firing (expressed by a low CV2) during wait is related to an increased power of local field potential (LFP) beta oscillations and phase locking of spikes to these oscillations. In renewal processes, a widely used model for spiking activity under stationary input conditions, both measures are related as FF ≈ CV2. This expectation was met during movement, but not during wait where FF ≫ CV22. Our interpretation is that during movement preparation, ongoing brain processes result in changing network states and thus in high trial-to-trial variability (expressed by a high FF). During movement execution, the network is recruited for performing the stereotyped motor task, resulting in reliable single neuron output. Our interpretation is in the light of recent computational models that generate non-stationary network conditions

Local field potentials in primate motor cortex encode grasp kinetic parameters

Reach and grasp kinematics are known to be encoded in the spiking activity of neuronal ensembles and in local field potentials (LFPs) recorded from primate motor cortex during movement planning and execution. However, little is known, especially in LFPs, about the encoding of kinetic parameters, such as forces exerted on the object during the same actions. We implanted two monkeys with microelectrode arrays in the motor cortical areas MI and PMd to investigate encoding of grasp-related parameters in motor cortical LFPs during planning and execution of reach-and-grasp movements. We identified three components of the LFP that modulated during grasps corresponding to low (0.3–7 Hz), intermediate (~ 10–~ 40 Hz) and high (~ 80–250 Hz) frequency bands. We show that all three components can be used to classify not only grip types but also object loads during planning and execution of a grasping movement. In addition, we demonstrate that all three components recorded during planning or execution can be used to continuously decode finger pressure forces and hand position related to the grasping movement. Low and high frequency components provide similar classification and decoding accuracies, which were substantially higher than those obtained from the intermediate frequency component. Our results demonstrate that intended reach and grasp kinetic parameters are encoded in multiple LFP bands during both movement planning and execution. These findings also suggest that the LFP is a reliable signal for the control of parameters related to object load and applied pressure forces in brain–machine interfaces

A spinal cord neuroprosthesis for locomotor deficits due to Parkinson’s disease

People with late-stage Parkinson’s disease (PD) often suffer from debilitating locomotor deficits that are resistant to currently available therapies. To alleviate these deficits, we developed a neuroprosthesis operating in closed loop that targets the dorsal root entry zones innervating lumbosacral segments to reproduce the natural spatiotemporal activation of the lumbosacral spinal cord during walking. We first developed this neuroprosthesis in a non-human primate model that replicates locomotor deficits due to PD. This neuroprosthesis not only alleviated locomotor deficits but also restored skilled walking in this model. We then implanted the neuroprosthesis in a 62-year-old male with a 30-year history of PD who presented with severe gait impairments and frequent falls that were medically refractory to currently available therapies. We found that the neuroprosthesis interacted synergistically with deep brain stimulation of the subthalamic nucleus and dopaminergic replacement therapies to alleviate asymmetry and promote longer steps, improve balance and reduce freezing of gait. This neuroprosthesis opens new perspectives to reduce the severity of locomotor deficits in people with PD

VIOLA—A Multi-Purpose and Web-Based Visualization Tool for Neuronal-Network Simulation Output

Neuronal network models and corresponding computer simulations are invaluable tools to aid the interpretation of the relationship between neuron properties, connectivity, and measured activity in cortical tissue. Spatiotemporal patterns of activity propagating across the cortical surface as observed experimentally can for example be described by neuronal network models with layered geometry and distance-dependent connectivity. In order to cover the surface area captured by today's experimental techniques and to achieve sufficient self-consistency, such models contain millions of nerve cells. The interpretation of the resulting stream of multi-modal and multi-dimensional simulation data calls for integrating interactive visualization steps into existing simulation-analysis workflows. Here, we present a set of interactive visualization concepts called views for the visual analysis of activity data in topological network models, and a corresponding reference implementation VIOLA (VIsualization Of Layer Activity). The software is a lightweight, open-source, web-based, and platform-independent application combining and adapting modern interactive visualization paradigms, such as coordinated multiple views, for massively parallel neurophysiological data. For a use-case demonstration we consider spiking activity data of a two-population, layered point-neuron network model incorporating distance-dependent connectivity subject to a spatially confined excitation originating from an external population. With the multiple coordinated views, an explorative and qualitative assessment of the spatiotemporal features of neuronal activity can be performed upfront of a detailed quantitative data analysis of specific aspects of the data. Interactive multi-view analysis therefore assists existing data analysis workflows. Furthermore, ongoing efforts including the European Human Brain Project aim at providing online user portals for integrated model development, simulation, analysis, and provenance tracking, wherein interactive visual analysis tools are one component. Browser-compatible, web-technology based solutions are therefore required. Within this scope, with VIOLA we provide a first prototype

Toward a Full Prehension Decoding from Dorsomedial Area V6A

Neural prosthetics represent a promising approach to restore movements in patients affected by spinal cord lesions. To drive a full capable, brain controlled, prosthetic arm, reaching and grasping components of prehension have to be accurately reconstructed from neural activity. Neurons in the dorsomedial area V6A of macaque show sensitivity to reaching direction accounting also for depth dimension, thus encoding positions in the entire 3D space. Moreover, many neurons are sensible to grips types and wrist orientations. To assess whether these signals are adequate to drive a full capable neural prosthetic arm, we recorded spiking activity of neurons in area V6A, spike counts were used to train machine learning algorithms to reconstruct reaching and grasping. In a first work, two Macaca fascicularis monkeys were trained to perform an instructed-delay reach-to-grasp task in the dark and in the light toward objects of different shapes. The activity of 89 neurons was used to train and validate a Bayes classifier used for decoding objects and grip types. Recognition rates were well above chance level for all the epochs analyzed in this study. In a second work, monkeys were trained to perform reaches to targets located at various depths and directions and the classifier was tested whether it could correctly predict the reach goal position from V6A signals. The reach goal location was reliably decoded with accuracy close to optimal (>90%) throughout the task. Together these results, show a reliable decoding of hand grips and spatial location of reaching goals in the same area, suggesting that V6A is a suitable site to decode the entire prehension action with obvious advantages in terms of implant invasiveness. This new PPC site useful for decoding both reaching and grasping opens new perspectives in the development of human brain-computer interfaces

Neural coding of grasp force planning and control in macaque areas AIP, F5, and M1

In den letzte Jahrzehnten wurde viel daran geforscht zu entschlüsseln wie das Gehirn Greifbewegungen koordiniert. Das anteriore intraparietale Areal (AIP), das Hand Areal des ventralen premotorischen Kortex (F5), und das Hand Areal des primären motorischen Kortex (M1) wurden als essentielle kortikale Arealen für die Kontrolle der Hand identifiziert. Nichtsdestotrotz ist deutlich weniger darüber bekannt wie die Neuronen dieser Areale einen weiteren essentielle Parameter von Greifbewegungen kodieren: Greifkraft. Insbesondere die Rolle der tertiären, kortikalen Areale AIP und F5 in diesen Prozess ist bisher unklar. Die hier durchgeführte Studie befasst sich mit der Wissenslücke über die neuronale Kodierung von Greifkraft Planung und Steuerung in diesen Arealen. Um dies zu erreichen, haben wir zwei Makaken (Macaca mulatta) trainiert eine verzögerte Greifaufgabe auszuführen mit zwei Grifftypen (ein Griff mit der ganzen Hand oder ein Präzisionsgriff) und mit drei verschiedene Kraftniveaus (0-12 N). Während die Affen die Aufgabe ausführten, haben wir die Aktivität von “single-units“ (einzelnen Neuronen) und “multi-units“ (Gruppen von mehreren Neuronen) in den Arealen AIP, F5 und M1 aufgenommen. Wir berechneten den Prozentsatz von Grifftyp modulierten und Griffkraft modulierten “units“ (cluster-based permutation test) und berechneten wie viel Varianz in der Population von “units“ durch Grifftyp und Kraft erklärbar ist, separat für jedes Gehirn Areal mit einer modernen Dimensionalitätsreduktionsanalyse (demixed principal component analysis). 18 Wir zeigen hier zum ersten Mal die Modulation von einzelnen AIP Neuronen durch Greifkraft. Weiterhin bestätigen und erweitern wir hier vorherige Ergebnisse, welche solche neuronale Modulationen bereits in F5 und M1 gezeigt haben. Überaschenderweise war der Prozentsatz von “units“ welche durch Griffkraft moduliert werden, in AIP und F5 nicht wesentlich kleiner als in M1 und ähnlich zu dem Prozentsatz an Grifftyp modulierte Neuronen. Der Anteil an erklärte Varianz in F5 durch Greifkraft war nahezu so groß, wie der Anteil erklärt durch Grifftyp. In AIP und M1 war klar mehr Varianz durch Grifftyp erklärt als durch Kraft, aber der Anteil an erklärte Varianz beider Arealen war ausreichend, um zuverlässig Kraftbedingung zu dekodieren. Wir fanden ebenfalls eine starke neuronale Modulation für Griffkraftbedingungen vor der Bewegungsinitiierung in F5, was wahrscheinlich eine Rolle dieses Areals in der Greifkraftplanung repräsentiert. In AIP war Greifkraftplanungsaktivität nur in einen der beiden Affen vorhanden und wie erwartet nicht präsent in M1 (gemessen nur in einen Affen). Letztendlich, obwohl Greifkraftmodulation in einigen Fällen durch Grifftypmodulation beeinflusst war, war nur ein kleiner Anteil der Populationsvarianz, in den jeweiligen Arealen, durch interaktive Modulation erklärt. Information über Greifkraft können somit folglich separat vom Grifftyp extrahiert werden. Diese Ergebnisse legen eine wichtige Rolle von AIP und F5 bei der Greifkraftkontrolle, neben M1, nah. F5 ist mit hoher Wahrscheinlichkeit auch bei der Planung von Greifkraft involviert, während die Rolle von AIP und M1 geringer ist in diesem Prozess. Letztendlich, da Grifftyp- und Kraftinformation separat extrahierbar sind, zeigen diese Ergebnisse, dass Greifkraft vermutlich unabhängig von Grifftyp, im kortikalen Greifnetzwerk kodiert ist.In de laatste decennia is er veel onderzoek gedaan om te interpreteren hoe de hersenen grijpbewegingen besturen. Het anterieure intra pariëtale gebied (AIP), het handgebied van de ventrale premotorische schors (F5) en het handgebied van de primaire motorische schors (M1) zijn geïdentificeerd als essentiële gebieden van de hersenschors die de vorm van de hand besturen. Maar er is veel minder bekend over hoe de hersenen een andere parameter van grijpbewegingen bestuurt: grijpkracht. Vooral de rol in dit proces van AIP en F5, gebieden van hogere orde, is nog nagenoeg onbekend. Deze studie richt zich op het gebrek aan kennis over de neurale codering van het plannen en besturen van grijpkracht. Om dit te bereiken, hebben we twee makaken (Macaca mulatta) getraind om een vertraagde grijptaak uit te voeren met twee grepen van de hand (een grip met de hele hand of een precisie grip) en met drie verschillende krachtniveaus (0-12 N). Terwijl de apen de taak uitvoerden, maten we de activiteit van single-units (individuele neuronen) en multiunits (collectie van enkele neuronen) in de gebieden AIP, F5 en M1. We berekenden het percentage van units die hun activiteit moduleerden op basis van grip vorm of kracht met een moderne statistieke test (cluster-based permutation test) en we berekenden de hoeveelheid variantie die werd verklaard door de grip vorm en kracht door de populatie van units van elk hersengebied met een moderne dimensie vermindering techniek (demixed principal component analysis). We laten hier voor het eerst zien dat individuele neuronen van AIP hun activiteit moduleren op basis van grijpkracht. Verder bevestigen we dat neuronen van F5 en M1 20 dergelijke modulaties vertonen en breiden we de kennis hierover uit. Verassend genoeg was het percentage units dat reageert op het besturen van grijpkracht in AIP en F5 niet veel lager dan in M1 en ongeveer gelijk aan de hoeveelheid units dat reageert op grip vorm. De hoeveelheid variantie die werd verklaard door grijpkracht in F5 was bijna net zo hoog als wat werd verklaard door grip vorm. In AIP en M1 verklaarde grip vorm duidelijk meer variantie dan grijpkracht, maar ook in deze gebieden was de hoeveelheid variantie dat grijpkracht verklaarde hoog genoeg om de kracht conditie te decoderen. We vonden ook een sterke neurale modulatie voor grijpkracht condities in F5 voordat de arm bewoog, wat mogelijk een rol voor dit gebied representeert in het plannen van grijpkracht. In AIP was activiteit voor het plannen van grijpkracht alleen in één van beide apen gevonden en zoals verwacht was het niet gevonden in M1 (onderzocht in één aap). Tenslotte vonden we dat, hoewel modulatie voor kracht werd beïnvloedt door grip vorm in sommige eenheden, slechts een kleine fractie van de variantie van de neurale populatie van elk hersengebied een gemixte selectiviteit voor grip vorm en kracht had. Informatie over grijpkracht kon daarom onafhankelijk van grip vorm worden geëxtraheerd. Deze bevindingen suggereren een belangrijke rol voor AIP en F5 in het besturen van grijpkracht, samen met M1. F5 is waarschijnlijk ook betrokken met het plannen van grijpkracht, terwijl AIP en M1 waarschijnlijk een kleinere rol hebben in dit proces. Tenslotte, omdat informatie over grip vorm en grijpkracht onafhankelijk konden worden geëxtraheerd, laten deze resultaten zien dat grijpkracht vermoedelijk onafhankelijk van hand vorm is gecodeerd in het grijpnetwerk van de hersenschors

De animais a máquinas : humanos tecnicamente melhores nos imaginários de futuro da convergência tecnológica

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Sociais, Departamento de Sociologia, 2020.O tema desta investigação é discutir os imaginários sociais de ciência e tecnologia que emergem a partir da área da neuroengenharia, em sua relação com a Convergência Tecnológica de quatro disciplinas: Nanotecnologia, Biotecnologia, tecnologias da Informação e tecnologias Cognitivas - neurociências- (CT-NBIC). Estas áreas desenvolvem-se e são articuladas por meio de discursos que ressaltam o aprimoramento das capacidades físicas e cognitivas dos seres humanos, com o intuito de construir uma sociedade melhor por meio do progresso científico e tecnológico, nos limites das agendas de pesquisa e desenvolvimento (P&D). Objetivos: Os objetivos nesse cenário, são discutir as implicações éticas, econômicas, políticas e sociais deste modelo de sistema sociotécnico. Nos referimos, tanto as aplicações tecnológicas, quanto as consequências das mesmas na formação dos imaginários sociais, que tipo de relações se estabelecem e como são criadas dentro desse contexto. Conclusão: Concluímos na busca por refletir criticamente sobre as propostas de aprimoramento humano mediado pela tecnologia, que surgem enquanto parte da agenda da Convergência Tecnológica NBIC. No entanto, as propostas de melhoramento humano vão muito além de uma agenda de investigação. Há todo um quadro de referências filosóficas e políticas que defendem o aprimoramento da espécie, vertentes estas que se aliam a movimentos trans-humanistas e pós- humanistas, posições que são ao mesmo tempo éticas, políticas e econômicas. A partir de nossa análise, entendemos que ciência, tecnologia e política estão articuladas, em coprodução, em relação às expectativas de futuros que são esperados ou desejados. Ainda assim, acreditamos que há um espaço de diálogo possível, a partir do qual buscamos abrir propostas para o debate público sobre questões de ciência e tecnologia relacionadas ao aprimoramento da espécie humana.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The subject of this research is to discuss the social imaginaries of science and technology that emerge from the area of neuroengineering in relation with the Technological Convergence of four disciplines: Nanotechnology, Biotechnology, Information technologies and Cognitive technologies -neurosciences- (CT-NBIC). These areas are developed and articulated through discourses that emphasize the enhancement of human physical and cognitive capacities, the intuition it is to build a better society, through the scientific and technological progress, at the limits of the research and development (R&D) agendas. Objectives: The objective in this scenery, is to discuss the ethic, economic, politic and social implications of this model of sociotechnical system. We refer about the technological applications and the consequences of them in the formation of social imaginaries as well as the kind of social relations that are created and established in this context. Conclusion: We conclude looking for critical reflections about the proposals of human enhancement mediated by the technology. That appear as a part of the NBIC technologies agenda. Even so, the proposals of human enhancement go beyond boundaries that an investigation agenda. There is a frame of philosophical and political references that defend the enhancement of the human beings. These currents that ally to the transhumanism and posthumanism movements, positions that are ethic, politic and economic at the same time. From our analysis, we understand that science, technology and politics are articulated, are in co-production, regarding the expected and desired futures. Even so, we believe that there is a space of possible dialog, from which we look to open proposals for the public discussion on questions of science and technology related to enhancement of human beings