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Views from the Beach: Spectator Positions and the American International Pictures Beach Party FilmsLeavy, Mark 07 1900 (has links)
The American International Pictures (AIP) Beach Party Films were a major American cultural phenomenon in the early 1960s and continue to play a significant role in the American cultural imagination. The AIP Beach Party Films, despite their popularity and influence, have been largely ignored by academia and a thorough academic examination has yet to be written. This thesis attempts to change such an academic precedent. At first glance, the Beach Party Films are frivolous and chaotic (perhaps explaining the lack of academic inquiry). However, upon closer examination, the Beach Party Films are laden with cultural artifacts, insights into American culture of the late 1950s and early 1960s and provide a view into the tenuous relationship between 1960s American dominant culture and developing countercultures. Further, the Beach Party Films reveal a 1960s cultural lull; a culture that was caught between the dominant culture of 1950s America and the explosive cultural changes of the late 1960s that had yet to occur. By closely looking at the AIP Beach Party Films, and doing so through the lens of various cultural critics, there can be described potential cultural perspectives from early 1960s America.
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Effectiveness of a Serpentine Inlet Duct Flow Control Scheme at Design and Off-Design Simulated Flight ConditionsRabe, Angela C. 27 October 2003 (has links)
An experimental investigation was conducted in a static ground test facility to determine the flow quality of a serpentine inlet duct incorporating active flow control for several simulated flight conditions. The total pressure distortion at the aerodynamic interface plane (AIP) was then used to predict the resulting stability for a compression system. This study was conducted using a model of a compact, low observable, engine inlet duct developed by Lockheed Martin. A flow control technique using air injection through microjets at 1% of the inlet mass flow rate was developed by Lockheed Martin to improve the quality of the flow exiting the inlet duct. Both the inlet duct and the flow control technique were examined at cruise condition and off-design simulated flight conditions (angle of attack and asymmetric distortion). All of the experimental tests were run at an inlet throat Mach number of 0.55 and a resulting Reynolds number of 1.76*105 based on the hydraulic diameter at the inlet throat.
For each of the flight conditions tested, the flow control scheme was found to improve the flow uniformity and reduce the inlet distortion at the AIP. For simulated cruise condition, the total pressure recovery was improved by ~2% with the addition of flow control. For the off-design conditions of angle of attack and asymmetric distortion, the total pressure recovery was improved by 1.5% and 2% respectively. All flight conditions tested showed a reduction in circumferential distortion intensity with flow control. The cruise condition case showed reduced maximum circumferential distortion of 70% with the addition of flow control. A reduction in maximum circumferential distortion of 40% occurred for the angle of attack case with flow control, and 30% for the asymmetric distortion case with flow control.
The inlet total pressure distortion was used to predict the changes in stability margin of a compression system due to design and off-design flight conditions and the improvement of the stability margin with the addition of flow control. A parallel compressor model (DYNTECC) was utilized to predict changes in the stability margin of a representative compression system (NASA Stage 35). Without flow control, all three cases show similar reduced stability margins on the order of 30% of the original stability margin for NASA Stage 35 at 70% corrected rotor speed. With the addition of flow control, the cruise condition tested improved the stability margin to 80% of the original value while the off-design conditions recover to 60% of the original margin. Overall, the flow control has been found to be extremely beneficial in improving the operating range of a compression system for the same inlet duct without flow control. / Ph. D.
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Implication d'AIP (Aryl hydrocarbon receptor Interacting Protein) dans la tumorigenèse des adénomes hypophysaires. / Role of AIP (Aryl Hydrocarbon Receptor Interacting Protein) in Pituitary Adenoma TumorigenesisLecoq, Anne-Lise 26 October 2015 (has links)
Nous avons souhaité, dans ce travail de Thèse, préciser l'impact de l'invalidation d'AIP sur la fonction sécrétoire et la prolifération des cellules somatotropes in vivo et explorer in vitro les voies de signalisation potentiellement impliquées dans la tumorigenèse hypophysaire AIP-dépendante. L'analyse du phénotype des souris Aip+/-, en particulier de la sécrétion pulsatile de GH, montre que, contrairement à l'Homme, les animaux mutés ne développent pas de gigantisme ni d'hypersécrétion de GH et que la pénétrance de la pathologie tumorale hypophysaire est beaucoup plus faible qu'initialement décrit. Les études réalisées sur les fibroblastes de patients mutés pour AIP et porteurs d'un adénome hypophysaire ainsi que sur les cellules somatolactotropes de rat GH3 révèlent que les mutations d'AIP altèrent l'activité transcriptionnelle d'AhR (Aryl hydrocarbon Receptor), mais affectent également la voie de signalisation de l'AMPc. Enfin, des mutations germinales du gène GPR101, récemment identifiées dans des cas d'acromégalie sporadique, ont aussi été trouvées chez des patients porteurs d'un adénome hypophysaire sporadique non somatotrope, sans association avec les mutations d'AIP. Ce travail a ainsi permis de préciser les conséquences des mutations d'AIP sur la fonction somatotrope et la signalisation d'AhR. Le rôle de l'AMPc dans la tumorigenèse hypophysaire AIP-dépendante sera évalué dans un nouveau modèle de souris transgénique. / In this work, we investigated the effects of AIP deficiency in vivo on somatotroph cells, both at the secretory and proliferative levels and explored in vitro the signaling pathways potentially involved in AIP-dependent pituitary tumorigenesis. Phenotype analyzes of Aip+/- mice, especially of GH pulsatility, show that, unlike humans, mutant mice do not develop gigantism nor GH hypersecretion and present with a much lower penetrance of pituitary adenomas than initially described. In vitro studies in fibroblasts of AIP-mutation positive patients with pituitary adenomas and in somatolactotroph GH3 cells demonstrate that AIP mutations alter AhR (Aryl hydrocarbon Receptor) transcriptional activity and modify the cAMP pathway. Finally, GPR101 mutations, recently reported in patients with sporadic acromegaly, have also been identified in a small portion of patients with sporadic non-somatotroph pituitary adenomas, without any association with AIP mutations. This research work defines the consequences of AIP mutations on somatotroph cell function and AhR transcriptional activity. The role of cAMP signaling in AIP-related pituitary tumorigenesis will be further evaluated in a new transgenic mouse model.
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Übertragbarkeit von Archivinformationspaketen zwischen Langzeitarchivsystemen als Teil der Exit-StrategieRomeyke, Andreas 13 April 2017 (has links)
Die vorliegende Arbeit beleuchtet, ob und unter welchen Voraussetzungen es möglich ist, Archivinformationspakete (AIP) als Zeitkapseln digitaler Medien, zwischen verschiedenen Langzeitarchivsystemen auszutauschen.
Dazu werden die Systeme Rosetta von Exlibris — a ProQuest Group und Archivematica von Artefactual Systems Inc. verglichen. Es wird untersucht, inwieweit eine Exit-Strategie Bestandteil von einigen zertifizierten Langzeitarchivsystem-Betreibern ist, und wie unterschiedlich Informationspakete verwendet werden. In der Arbeit wird der Begriff AIP-AIP-Transfer definiert und verschiedene AIP-Übernahme-Szenarien vorgestellt.:1. Einführung
1.1. Motivation
1.2. Aufbau der Arbeit
2. Exit-Strategie als Baustein der digitalen Langzeitarchivierung
2.1. Digitale Langzeitarchivierung
2.2. Begriff der Exit-Strategie
2.3. Fragestellung und Bedeutung
2.4. Aktueller Stand der Wissenschaft und Technik
2.4.1. Exit-Strategien von zertifizierten Archivinformationssystemen
2.4.2. Informationspakete
2.4.3. AIP-AIP-Transfer
2.5. Abgrenzung
3. Vorbereitung der Untersuchung
3.1. Vorbetrachtung
3.2. Aufbau und Varianten von Submission Information Packages
3.2.1. Allgemeines
3.2.2. Abbildung zwischen Intellektuellen Einheiten und SIP
3.2.3. Technische Realisierungen von SIPs
3.2.4. Technische Realisierungen von AIPs
3.3. Ingest
3.4. Typische AIP Update Szenarien
3.4.1. Was ist ein AIP Update
3.4.2. Bedingungen
3.4.3. Metadatenupdate
3.4.4. Repräsentations- und Datenupdates
3.4.5. Löschen von AIPs
3.4.6. Preservation Planning and Action
3.5. AIP-AIP Transfer Szenarien
3.5.1. Allgemein
3.5.2. Übernahme AIP → AIP über definierte Schnittstelle
3.5.3. Übernahme AIP → AIP über Direktzugriff Quell- und Zielsystem
3.5.4. Übernahme AIP → SIP → AIP über Direktzugriff Quellsystem
3.5.5. Übernahme AIP → DIP → SIP → AIP
3.5.6. Vergleichskriterien
3.6. Betrachtete Langzeitarchivierungssysteme
3.6.1. Archivematica
3.6.2. Rosetta
3.6.3. Zusammenfassende Gegenüberstellung
4. Durchführung
4.1. Beschränkung
4.2. Festlegungen
4.2.1. Festlegung Submission Information Package
4.2.2. Festlegung Metadatenanreicherung (Enrichment)
4.2.3. Festlegung AIP Update Szenarien
4.3. Zugriff auf AIPs
4.4. Analyse der entstandenen AIPs
4.4.1. AIPs von Archivematica
4.4.2. AIPs von Rosetta
4.5. Direkte Übernahme von AIPs
4.6. Archivematica AIP als Rosetta SIP
4.7. Rosetta AIP als Archivematica SIP
5. Bewertung und Ausblick
5.1. Ausspielen AIPs
5.2. Aufbau der AIPs
5.3. Bewahrungsmetadaten
5.4. Einspielen von SIPs
5.5. Empfehlungen
5.6. Beurteilung anhand Vergleichskriterien
5.7. Ausblick
A. Zusätzliche Abbildungen und Quellcodes
B. Literatur
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Acute interstitial pneumonia in feedlot cattleValles, Jose Antonio January 1900 (has links)
Master of Science / Department of Clinical Sciences / Daniel U. Thomson / Acute Interstitial Pneumonia (AIP) is a costly issue that affects feedlot cattle, especially during hot and dry summers. Research has yet to elucidate the exact etiology of AIP; therefore this study was conducted to determine possible factors that contribute to AIP in feedlot cattle. During the summer of 2011 in a 55,000 head feedyard in southwest Kansas, animals exhibiting clinical signs of AIP were selected for ante-mortem examination and data collection. The animal population within the feedlot consisted of 75% heifers and 25% steers. Approximately 50% of the animal population was black hided animals. Ante-mortem data consisted of rumen gas cap measurement for NH3 and H2S, rumen pH, serum chemistry, rectal temperature, and body weight. Post-mortem cases with and without ante-mortem evaluations were also selected for an additional examination. Postmortem examination included similar data as ante-mortem examination with addition of visual and histological examination of lung tissue. There were 31 ante-mortem cases of clinical AIP with the following observations (mean ± SD): rectal temperature 105.3 ± 0.7 °F, weight 1098 ± 123 lbs., H2S 136 ± 133.3 ppm, and rumen pH 6.4 ± 0.5. Twenty-five healthy cohorts were selected from identical pens to serve as controls. Observations from control animals were: rectal temperature 103.7 ± 1.1 °F, weight 1113 ± 133.3lbs, H2S 269.8 ± 311.6 ppm and rumen pH 6.2 ± 0.6. A total of 61 post-mortem cases with a preliminary diagnosis of AIP were analyzed and displayed the following values: H2S 1279.7 ± 1569 ppm, and rumen pH 6.3 ± 0.36. Fifty-three of these postmortem cases had diffuse, focal and /or patchy AIP confirmed by histology.
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Synthesis of the accessory gene regulator autoinducing peptide in Staphylococcus aureusThoendel, Matthew James 01 May 2012 (has links)
The accessory gene regulator (agr) quorum-sensing system is one of the major regulators of virulence factor production in the pathogen Staphylococcus aureus. Activation of the system depends on the production and sensing of a cyclic peptide signal called the autoinducing peptide (AIP). The biosynthesis of AIP depends on the coordinated action of the AgrB integral membrane endopeptidase and SpsB signal peptidase to process the peptide precursor AgrD into the final signal structure. The primary goal of this dissertation was to gain further insight on the role of AgrD and AgrB in the AIP biosynthesis mechanism. Studies in Chapter II were undertaken to better understand the role of AgrD domains in AgrB-mediated processing. A series of truncation and site-directed mutagenesis studies identified key residues in the AgrD C-terminus that were essential for AgrB processing and AIP production. In parallel, genetic manipulation of the N-terminal leader and AIP-encoding sequence revealed a role for these segments in AIP processing. For the first time, a complex of AgrD covalently linked to AgrB was identified, supporting proposals that this intermediate is an important precursor to AIP production. In Chapter III structure-function studies were performed on AgrB to gain further insight into the AIP biosynthetic mechanism. Initially, the agrBD genes were subjected to random mutagenesis and screened for deficiencies in AIP production. Single-site mutations at 20 different residues within AgrB and another 14 in AgrD were isolated. Interestingly, new mutations in the AgrD N-terminal leader were identified that affect AIP biosynthesis at different steps. In AgrB, most of the mutations blocked peptidase activity, but charge alterations to the K129-K131 region were defective in a later pathway step, separating the peptidase function from AIP ring formation and transport. To localize the AgrB mutations, we reevaluated the membrane topology using the substituted cysteine accessibility method. Our new model predicts four transmembrane helices and a reentrant loop, with both termini located outside of the cell. Finally, co-immunoprecipitation studies indicate that AgrB forms oligomeric structures within the membrane. Taken together, these findings provide a better understanding of the functional role of specific AgrD and AgrB regions in AIP biosynthesis.
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The structural nature of aluminosilicate inorganic polymers: a macro to nanoscale studyRowles, Matthew Ryan January 2004 (has links)
Aluminosilicate inorganic polymers (AIPs) are network heteropolymers consisting of Si04 and AlO4 tetrahedra linked by a shared oxygen. The use of these materials as a cementing agent, toxic waste storage and fibre reinforced material, amongst a multitude of prospective applications, has grown in recent years. The utilisation of AIPs is hampered by a lack of knowledge about their formation and structure. In order to allow the materials to achieve their full potential, the way in which the material behaves and forms under different conditions must be elucidated. The basic questions that this study aimed to answer were: 1) How does the structure of these AIPs change with composition? and 2) Can this change in structure explain the material properties of the AIP? The AIPs investigated in the study covered the molar composition ranges Si:Al ratio = 1 - 3 and Na:Al ratio = 0.5 - 2. They were made by the sodium hydroxide activation of metakaolinite, derived from the dehydroxylation of kaolinite. The Si content of the AIP was altered by the addition of amorphous silica fume via the activation solution. The study considered the structural nature of the AIPs at the macro, micro and nanoscales, and found that the structure changed at all scales and with all compositions. The nature of the AIP structure was studied at the macroscale utilising compressive strength testing. The results from this work showed that the compressive strength of the AIPs varied systematically with the chemical composition. The strengths recorded ranged from 0.4 ± 0.2 MPa for a sample with Si:Al:Na molar ratios = 1.08:1:0.5, to 64 ± 3 MPa for a sample with Si:Al:Na molar ratios = 2.5:1:1.3. The higher strengths measured exceed those exhibited by Portland cement pastes. The microstructure of the AIPs was investigated by scanning electron microscopy and energy dispersive spectroscopy. / Microscopy showed that the microstructure variations correlated with the compressive strength. In general, AIPs with low compressive strengths exhibited an inhomogeneous two-phase microstructure; grain and matrix. The grain phase consisted of undissolved metakaolinite, whilst the matrix was the fully formed inorganic polymer. AIPs with high compressive strengths exhibited a microstructure that was more homogeneous than the samples with low compressive strength. The compressive strength of the AIPs depended on both the chemical composition and the level of residual MK present in the microstructure. EDS microanalysis showed that the composition of the two phases was significantly different, and that the differences depended on the overall composition of the AIP. EDS results also demonstrated that the impurity elements present in the metakaolinite were affected by the polymerisation process. Soluble elements such as Ca and Mg were found primarily in the matrix, indicating that they had leached out of the metakaolinite grains, whereas insoluble elements such as Fe and Ti were found primarily in the grains. The nanoscale structure of the AIPs was examined by solid-state nuclear magnetic resonance (NMR) and x-ray scattering (XRS). The NMR measurements revealed that the average coordination of Si varied according to the composition of the AIP, whereas the coordination of Al was constant. Na is present in the network in both hydrated and non-hydrated forms. It is postulated that the variation in the Si coordination can be explained by the formation of Si-O-Na bonds with Na forming an ionic bond with 0 in the polymer network. Radial distribution function (RDF) analysis of the XRS patterns revealed little difference in the structure of the different AIPs beyond ~2.5 Å. / Unfortunately, the data were of insufficient resolution to allow for a full evaluation of the differences in the Si-O and Al-O bonds between different AIPs. However, the trends present in the shape and position of the RDF peak corresponding to the Si-O and Al-O bonds do follow the composition of the AIP. It has been shown that a variety of experimental techniques can be used in concert to obtain information on the structural nature of AIPs. To this end, it has been found that the compressive strength of AIPs can be optimised, and that the microstructure of the AIPs changes systematically with variations in the compressive strength. An improved model for the structure of AIPs has also been proposed.
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Vliv inhibitorů BSO, Lycorine a AIP na biosyntézu sekundárních metabolitů jednobuněčné řasy Scenedesmus quadricaudaRankić, Ivan January 2018 (has links)
The theoretical overview summarize the characteristics of algae and their primary and secondary metabolism. It also deals with inhibitors of ascorbic acid, glutathione and polyphenolic compounds synthesis. The practical part studies the influence of selected inhibitors (BSO, Lyc, AIP) and CdCl2 on the secondary metabolites production and biomass growth in freshwater microalgae Scenedesmus quadricauda. The content of secondary metabolites (eg. caffeic acid, chlorogenic acid, salicylic acid, cinnamic acid, p-coumaric acid) was detected by HPLC-MS. Furthermore, the total antioxidant capacity, the total polyphenol content and the total flavonoid content was determined spectrophotometrically. All the inhibitors used, reduced S. quadricauda growth in comparison with control samples. The most pronounced inhibitory effect was observed in the samples treated with Lyc + Cd after 7 days of experiment. All the treated samples responded to the stress factors by altering metabolic pathways and inhibiting growth. As a result, there were changes in the composition and the amount of selected secondary metabolites versus the control samples. At the same time, in most cases, the biosynthesis of polyphenolic and flavonoid substances has been stimulated. The oxidative reduction equilibrium and the induction of oxidative stress were probably impaired.
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Paleodiet och Paleokost : En studie i förhållandet mellan arkeologisk forskning och moderna hälsotrender / Paleodiet and Paleofood : A study in the relationship between archeologicalscience and modern health trendsSievers, Viggo January 2023 (has links)
Den här studien analyserar den moderna paleodieten genom en postmodernistisk teori och observerar om de aktörer som förespråkar den moderna paleodieten har ett nyanserat och problematiserande förhållningsätt till paleodieten. Studien baseras på fyra källor skrivna av tre aktörer, två böcker av arkeologen Göran Burenhult. Ytterligare en källa är The Paleo Solutionav Robb Wolf, den fjärde källan som förespråkar paleodieten är Swedish Paleo, ett företag som marknadsför paleodieten samt AIP-dieten online. Marlene Zuk är i sin bok Paleofantasymotståndare till paleodieten och hennes argument står i kontrast till de andra källorna. Honräknas dock inte som en huvudaktör och granskas inte av studien. Istället används hon endast för att analysera det positiva metanarrativet kring paleodieten. Studien kommer fram till att förespråkare för den moderna paleodieten ofta exkluderar information som motsäger den bildav dieten som de vill presentera. / This study analyses the modern paleodiet through a postmodernist lens and tries to find out if the proponents of the diet have a honest approach to archeological science. The study is based on four sources written by three individuals, two books by the archeologist Göran Burenhult, another source is The Paleo Solution by Robb Wolf. The fourth positive source to the paleodiet is Swedish Paleo, a company which markets the paleodiet and AIP-diet online. Marlene Zuk in her book Paleofantasy is an opponent to the paleodiet and her arguments are in opposition to the other sources. She is not however considered to be a main actor to be analyzed in this study, instead her arguments are only meant to analyze the positive metanarrative which proponents of the paleodiet advocates. The result of the study is that the modern paleodiet often excludesinformation which contradicts the image of the paleodiet the proponents of the diet wants to present.
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Neural coding of grasp force planning and control in macaque areas AIP, F5, and M1in 't Veld, Rijk 20 September 2016 (has links)
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).
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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
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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.
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