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1.
Eur J Neurosci ; 60(5): 5086-5110, 2024 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-39120435

RESUMEN

This systematic review and meta-analysis assesses independently the acute effects of anodal and cathodal motor cortex transcranial direct current stimulation (tDCS) on athletic performance in healthy adults. Besides, it evaluates the unique and conjoint effects of potential moderators (i.e., stimulation parameters, exercise type, subjects' training status and risk of bias). Online database search was performed from inception until March 18th 2024 (PROSPERO: CRD42023355461). Forty-three controlled trials were included in the systematic review, 40 in the anodal tDCS meta-analysis (68 effects), and 9 (11 effects) in the cathodal tDCS meta-analysis. Performance enhancement between pre- and post-stimulation was the main outcome measure considered. The anodal tDCS effects on physical performance were small to moderate (g = .29, 95%CI [.18, .40], PI = -.64 to 1.23, I2 = 64.0%). Exercise type, training status and use of commercial tDCS were significant moderators of the results. The cathodal tDCS effects were null (g = .04, 95%CI [-.05, .12], PI = -.14 to .23, I2 = 0%), with a small to moderate heterogeneity entirely due to sampling error, thus impairing further moderator analysis. These findings hold significant implications for the field of brain stimulation and physical performance, as they not only demonstrate a small to moderate effect of acute tDCS but also identify specific categories of individuals, devices and activities that are more susceptible to improvements. By addressing the multidimensional factors influencing the mechanisms of tDCS, we also provide suggestions for future research.


Asunto(s)
Rendimiento Atlético , Corteza Motora , Estimulación Transcraneal de Corriente Directa , Estimulación Transcraneal de Corriente Directa/métodos , Humanos , Corteza Motora/fisiología , Rendimiento Atlético/fisiología , Adulto
2.
Cereb Cortex ; 33(14): 9154-9164, 2023 07 05.
Artículo en Inglés | MEDLINE | ID: mdl-37246154

RESUMEN

Sensorimotor integration processes play a central role in daily life and require that different sources of sensory information become integrated: i.e. the information related to the object being under control of the agent (i.e. indicator) and the information about the goal of acting. Yet, how this is accomplished on a neurophysiological level is contentious. We focus on the role of theta- and beta-band activities and examine which neuroanatomical structures are involved. Healthy participants (n = 41) performed 3 consecutive pursuit-tracking EEG experiments in which the source of visual information available for tracking was varied (i.e. that of the indicator and the goal of acting). The initial specification of indicator dynamics is determined through beta-band activity in parietal cortices. When information about the goal was not accessible, but operating the indicator was required nevertheless, this incurred increased theta-band activity in the superior frontal cortex, signaling a higher need for control. Later, theta- and beta-band activities encode distinct information within the ventral processing stream: Theta-band activity is affected by the indicator information, while beta-band activity is affected by the information about the action goal. Complex sensorimotor integration is realized through a cascade of theta- and beta-band activities in a ventral-stream-parieto-frontal network.


Asunto(s)
Electroencefalografía , Lóbulo Frontal , Humanos , Lóbulo Frontal/fisiología , Sensación , Motivación , Transducción de Señal , Ritmo Teta/fisiología
3.
Behav Res Methods ; 56(1): 433-446, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-36698001

RESUMEN

In daily life, sensorimotor integration processes are fundamental for many cognitive operations. The pursuit-tracking paradigm is an ecological and valid paradigm to examine sensorimotor integration processes in a more complex environment than many established tasks that assess simple motor responses. However, the analysis of pursuit-tracking performance is complicated, and parameters quantified to examine performance are sometimes ambiguous regarding their interpretation. We introduce an open-source algorithm (TRACK) to calculate a new tracking error metric, the spatial error, based on the identification of the intended target position for the respective cursor position. The identification is based on assigning cursor and target direction changes to each other as key events, based on the assumptions of similarity and proximity. By applying our algorithm to pursuit-tracking data, beyond replication of known effects such as learning or practice effects, we show a higher precision of the spatial tracking error, i.e., it fits our behavioral data better than the temporal tracking error and thus provides new insights and parameters for the investigation of pursuit-tracking behavior. Our work provides an important step towards fully utilizing the potential of pursuit-tracking tasks for research on sensorimotor integration processes.


Asunto(s)
Aprendizaje , Desempeño Psicomotor , Humanos , Desempeño Psicomotor/fisiología , Aprendizaje/fisiología , Estimulación Luminosa , Seguimiento Ocular Uniforme
4.
J Neurosci Res ; 100(9): 1664-1694, 2022 09.
Artículo en Inglés | MEDLINE | ID: mdl-35582757

RESUMEN

Noninvasive brain stimulation (NIBS) techniques such as transcranial magnetic stimulation and transcranial direct current stimulation are widely used to test the involvement of specific cortical regions in various domains such as cognition and emotion. Despite the capability of stimulation techniques to test causal directions, this approach has been only sparsely used to examine the cortical regulation of autonomic nervous system (ANS) functions such as heart rate (HR) and heart rate variability (HRV) and to test current models in this regard. In this preregistered (PROSPERO) systematic review and meta-analysis, we aimed to investigate, based on meta-regression, whether NIBS represents an effective method for modulating HR and HRV measures, and to evaluate whether the ANS is modulated by cortical mechanisms affected by NIBS. Here we have adhered to the PRISMA guidelines. In a series of four meta-analyses, a total of 131 effect sizes from 35 sham-controlled trials were analyzed using robust variance estimation random-effects meta-regression technique. NIBS was found to effectively modulate HR and HRV with small to medium effect sizes. Moderator analyses yielded significant differences in effects between stimulation of distinct cortical areas. Our results show that NIBS is a promising tool to investigate the cortical regulation of ANS, which may add to the existing brain imaging and animal study literature. Future research is needed to identify further factors modulating the size of effects. As many of the studies reviewed were found to be at high risk of bias, we recommend that methods to reduce potential risk of bias be used in the design and conduct of future studies.


Asunto(s)
Estimulación Transcraneal de Corriente Directa , Animales , Encéfalo/fisiología , Cognición , Frecuencia Cardíaca , Estimulación Transcraneal de Corriente Directa/métodos , Estimulación Magnética Transcraneal/métodos
5.
Nutr Neurosci ; 25(12): 2616-2626, 2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34772324

RESUMEN

Human research has shown interactions between rewards and cognitive control. In animal models of affective neuroscience, reward administration typically involves administering orosensory sugar signals (OSS) during caloric-deprived states. We adopted this procedure to investigate neurophysiological mechanisms of reward-cognitive control interactions in humans. We predicted that OSS would affect neurophysiological and behavioral indices of error processing oppositely, depending on the relative weight of the OSS-induced 'wanting' and 'liking' components of reward. We, therefore, conducted a double-blind, non-nutritive sweetener-controlled study with a within-subject design. Fasted (16 hr) participants (N = 61) performed a modified Flanker task to assess neurophysiological (error-related negativity [Ne/ERN]) and behavioral (post-error adaptations) measures of error processing. Non-contingent to task performance, we repeatedly administered either a sugar (glucose) or non-nutritive sweetener (aspartame) solution, which had to be expulsed after short oral stimulation to prevent post-oral effects. Consistent with our hypothesis on how 'liking' would affect Ne/ERN amplitude, we found the latter to be decreased for sugar compared to aspartame. Unexpectedly, we found post-error accuracy, instead of post-error slowing, to be reduced by sugar relative to aspartame. Our findings suggest that OSS may interact with error processing through the 'liking' component of rewards. Adopting our reward-induction procedure (i.e. administering OSS in a state of high reward sensitivity [i.e. fasting], non-contingent to task performance) might help future research investigating the neural underpinnings of reward-cognitive control interactions in humans.


Asunto(s)
Preferencias Alimentarias , Edulcorantes no Nutritivos , Animales , Humanos , Apetito/fisiología , Aspartame , Preferencias Alimentarias/fisiología , Recompensa , Azúcares , Método Doble Ciego
6.
Z Psychosom Med Psychother ; 65(4): 321-340, 2019 Dec.
Artículo en Alemán | MEDLINE | ID: mdl-31328676

RESUMEN

Why the concept of distinct psychotherapeutic approaches is indispensable - and why the tool box concept of psychotherapy cannot work Background: In Germany, the official psychotherapy guidelines are oriented towards the model of distinct psychotherapeutic approaches. Within the German health care system this also applies to the training in psychotherapy. Some critics, however, are presently pleading in favour of abolishing the model of distinct psychotherapeutic approaches, which also implies to abolish the concept of the so called "Richtlinienverfahren" in Germany - approaches of psychotherapy which proved to be efficacious and whose costs are reimbursed by the insurance companies. Objective: The arguments put forward such as the heterogeneity of the approaches as well as the proposed alternatives, for example, an "integrative" model of both mental disorders and psychotherapeutic treatment are critically discussed. Results: Both the arguments and proposed alternatives are found to be not convincing, neither from a scientific nor from a psychotherapeutic perspective. From a scientific perspective, there is no evidence for efficacy of a "general" or "integrative" model of psychotherapy - which is in contrast to the Richtlinienverfahren for which evidence for efficacy exists. From a psychotherapeutic perspective psychotherapy cannot be taught, learnt and applied by use of tools or modules without a theoretical orientation. Conclusions: The concept of distinct psychotherapeutic approaches proves to be an in dispensable principal for orientation in psychotherapy, for both therapists and patients.


Asunto(s)
Psicoterapia/métodos , Alemania , Humanos , Trastornos Mentales/terapia
7.
Addict Biol ; 22(5): 1355-1365, 2017 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-27238886

RESUMEN

Effects of binge drinking on cognitive control and response selection are increasingly recognized in research on alcohol (ethanol) effects. Yet, little is known about how those processes are modulated by hangover effects. Given that acute intoxication and hangover seem to be characterized by partly divergent effects and mechanisms, further research on this topic is needed. In the current study, we hence investigated this with a special focus on potentially differential effects of alcohol intoxication and subsequent hangover on sub-processes involved in the decision to select a response. We do so combining drift diffusion modeling of behavioral data with neurophysiological (EEG) data. Opposed to common sense, the results do not show an impairment of all assessed measures. Instead, they show specific effects of high dose alcohol intoxication and hangover on selective drift diffusion model and EEG parameters (as compared to a sober state). While the acute intoxication induced by binge-drinking decreased the drift rate, it was increased by the subsequent hangover, indicating more efficient information accumulation during hangover. Further, the non-decisional processes of information encoding decreased with intoxication, but not during hangover. These effects were reflected in modulations of the N2, P1 and N1 event-related potentials, which reflect conflict monitoring, perceptual gating and attentional selection processes, respectively. As regards the functional neuroanatomical architecture, the anterior cingulate cortex (ACC) as well as occipital networks seem to be modulated. Even though alcohol is known to have broad neurobiological effects, its effects on cognitive processes are rather specific.


Asunto(s)
Intoxicación Alcohólica/fisiopatología , Consumo Excesivo de Bebidas Alcohólicas/fisiopatología , Encéfalo/fisiopatología , Cognición/fisiología , Potenciales Evocados/fisiología , Adulto , Atención , Electroencefalografía , Giro del Cíngulo/fisiopatología , Voluntarios Sanos , Humanos , Masculino , Modelos Neurológicos , Lóbulo Occipital/fisiopatología , Adulto Joven
8.
Behav Brain Res ; 469: 115063, 2024 07 09.
Artículo en Inglés | MEDLINE | ID: mdl-38777262

RESUMEN

Goal-directed acting requires the integration of sensory information but can also be performed without direct sensory input. Examples of this can be found in sports and can be conceptualized by feedforward processes. There is, however, still a lack of understanding of the temporal neural dynamics and neuroanatomical structures involved in such processes. In the current study, we used EEG beamforming methods and examined 37 healthy participants in two well-controlled experiments varying the necessity of anticipatory processes during goal-directed action. We found that alpha and beta activity in the medial and posterior cingulate cortex enabled feedforward predictions about the position of an object based on the latest sensorimotor state. On this basis, theta band activity seems more related to sensorimotor representations, while beta band activity would be more involved in setting up the structure of the neural representations themselves. Alpha band activity in sensory cortices reflects an intensified gating of the anticipated perceptual consequences of the to-be-executed action. Together, the findings indicate that goal-directed acting through the anticipation of the predicted state of an effector is based on accompanying processes in multiple frequency bands in midcingulate and sensory brain regions.


Asunto(s)
Electroencefalografía , Imaginación , Humanos , Masculino , Femenino , Adulto , Adulto Joven , Imaginación/fisiología , Objetivos , Encéfalo/fisiología , Ritmo alfa/fisiología , Giro del Cíngulo/fisiología , Anticipación Psicológica/fisiología , Ritmo beta/fisiología , Desempeño Psicomotor/fisiología , Ondas Encefálicas/fisiología
9.
Pflege ; 26(4): 245-53, 2013 Aug.
Artículo en Alemán | MEDLINE | ID: mdl-23876661

RESUMEN

In the interdisciplinary treatment process nurses play an important role, assessing suicide risk. To cope with this responsibility, the use of assessment instruments is recommended. Although a lot of instruments exist to assess the risk of suicide, nurses do not use them consistently. This cross-sectional study seeks to answer the following questions: How do nurses assess the suicidality of patients of psychiatric hospitals in the German speaking part of Switzerland? Do they use assessment instruments and if so, which ones? Ward nurses in every psychiatric hospital (n = 32) were asked about the state of the nursing practice in assessing the suicide risk by means of an electronic questionnaire. The following results emerged: Nurses use instruments to assess suicide risk on about half of the wards (n = 119, 50.63%). 13% of the mentioned instruments are research-based. Nurses mostly assess suicide endangerment in the case of a presumed danger, less often at admission and least often during the discharge process. As suicidality is assessed mostly when nurses assume a danger in this study, and due to the fact that suicides most frequently occur shortly prior to or during the discharge process, an expansion of or the introduction of the assessment is recommended before the discharge process.


Asunto(s)
Hospitales Psiquiátricos , Evaluación en Enfermería/métodos , Enfermería Psiquiátrica , Medición de Riesgo/métodos , Prevención del Suicidio , Suicidio/psicología , Competencia Clínica , Conducta Cooperativa , Hospitales Universitarios , Humanos , Comunicación Interdisciplinaria , Intuición , Relaciones Enfermero-Paciente , Admisión del Paciente/estadística & datos numéricos , Alta del Paciente/estadística & datos numéricos , Psicometría/estadística & datos numéricos , Reproducibilidad de los Resultados , Ideación Suicida , Suicidio/estadística & datos numéricos , Suiza
10.
PeerJ ; 11: e15286, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37223118

RESUMEN

An effective interaction with the environment requires adaptation of one's own behaviour to environmental demands. We do so by using cues from our environment and relating these cues to our body to predict the outcomes of events. The recent literature on embodied cognition suggests that task-relevant stimuli, presented near the hands, receive more attentional capacity and are processed differently than stimuli, presented spatially more distant to our body. It has also been proposed that near-hand processing is beneficial to conflict resolution. In the current study, we tested the assumption of an attentional bias towards the near hand space in the context of our previous work by combining a cueing paradigm (allocation of visual attention) with a conflict processing paradigm (Simon task) in the near vs far hand space. In addition, the relevance of processing was manipulated by using affective (angry vs neutral smileys) gaze cues (i.e., varying the valence of the cues). Our results indicate that (a) the interaction of valence × cue congruency × hand proximity was significant, indicating that the cueing effect was larger for negative valence in the proximal condition. (b) The interaction of valence × Simon compatibility × stimulus-hand proximity interaction was significant, indicating that for negative valence processing, the Simon effect was smaller in the proximal than in the distal stimulus-hand condition. This effect was at least numerically but not significantly reversed in the neutral valence condition. (c) Overall, cue congruency, indicating the correct vs incorrect attention allocation to the target stimulus onset, did not reveal any effect on Simon compatibility × stimulus-hand proximity. Our results suggest that valence, the allocation of attention, and conflict, seem to be decisive factors determining the direction and strength of hand proximity effects.


Asunto(s)
Señales (Psicología) , Mano , Extremidad Superior , Cognición , Aclimatación
11.
iScience ; 26(7): 106939, 2023 Jul 21.
Artículo en Inglés | MEDLINE | ID: mdl-37332673

RESUMEN

Monitoring actions is essential for goal-directed behavior. However, as opposed to short-lasting, and regularly reinstating monitoring functions, the neural processes underlying continuous action monitoring are poorly understood. We investigate this using a pursuit-tracking paradigm. We show that beta band activity likely maintains the sensorimotor program, while theta and alpha bands probably support attentional sampling and information gating, respectively. Alpha and beta band activity are most relevant during the initial tracking period, when sensorimotor calibrations are most intense. Theta band shifts from parietal to frontal cortices throughout tracking, likely reflecting a shift in the functional relevance from attentional sampling to action monitoring. This study shows that resource allocation mechanisms in prefrontal areas and stimulus-response mapping processes in the parietal cortex are crucial for adapting sensorimotor processes. It fills a knowledge gap in understanding the neural processes underlying action monitoring and suggests new directions for examining sensorimotor integration in more naturalistic experiments.

12.
Psychophysiology ; 60(1): e14146, 2023 01.
Artículo en Inglés | MEDLINE | ID: mdl-35816288

RESUMEN

Actions can fail - even though this is well known, little is known about what distinguishes neurophysiological processes preceding errors and correct actions. In this study, relying on the Theory of Event Coding, we test the assumption that only specific aspects of information coded in EEG activity are relevant for understanding processes leading to response errors. We examined N = 69 healthy participants who performed a mental rotation task and combined temporal EEG signal decomposition with multivariate pattern analysis (MVPA) and source localization analyses. We show that fractions of the EEG signal, primarily representing stimulus-response translation (event file) processes and motor response representations, are essential. Stimulus representations were less critical. The source localization results revealed widespread activity modulations in structures including the frontopolar, the middle and superior frontal, the anterior cingulate cortex, the cuneus, the inferior parietal cortex, and the ventral stream regions. These are associated with differential effects of the neural dynamics preceding correct/erroneous responses. The temporal-generalization MVPA showed that event file representations and representations of the motor response were already distinct 200 ms after stimulus presentation and this lasted till around 700 ms. The stability of this representational content was predictive for the magnitude of posterror slowing, which was particularly strong when there was no clear distinction between the neural activity profile of event file representations associated with a correct or an erroneous response. The study provides a detailed analysis of the dynamics leading to an error/correct response in connection to an overarching framework on action control.


Asunto(s)
Lóbulo Occipital , Lóbulo Parietal , Humanos , Lóbulo Parietal/fisiología , Giro del Cíngulo , Percepción , Desempeño Psicomotor/fisiología
13.
Front Public Health ; 11: 1063250, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37089489

RESUMEN

Introduction: Exposure to space conditions during crewed long-term exploration missions can cause several health risks for astronauts. Space radiation, isolation and microgravity are major limiting factors. The role of astrocytes in cognitive disturbances by space radiation is unknown. Astrocytes' response toward low linear energy transfer (LET) X-rays and high-LET carbon (12C) and iron (56Fe) ions was compared to reveal possible effects of space-relevant high-LET radiation. Since astronauts are exposed to ionizing radiation and microgravity during space missions, the effect of simulated microgravity on DNA damage induction and repair was investigated. Methods: Primary murine cortical astrocytes were irradiated with different doses of X-rays, 12C and 56Fe ions at the heavy ion accelerator GSI. DNA damage and repair (γH2AX, 53BP1), cell proliferation (Ki-67), astrocytes' reactivity (GFAP) and NF-κB pathway activation (p65) were analyzed by immunofluorescence microscopy. Cell cycle progression was investigated by flow cytometry of DNA content. Gene expression changes after exposure to X- rays were investigated by mRNA-sequencing. RT-qPCR for several genes of interest was performed with RNA from X-rays- and heavy-ion-irradiated astrocytes: Cdkn1a, Cdkn2a, Gfap, Tnf, Il1ß, Il6, and Tgfß1. Levels of the pro inflammatory cytokine IL-6 were determined using ELISA. DNA damage response was investigated after exposure to X-rays followed by incubation on a 2D clinostat to simulate the conditions of microgravity. Results: Astrocytes showed distinct responses toward the three different radiation qualities. Induction of radiation-induced DNA double strand breaks (DSBs) and the respective repair was dose-, LET- and time-dependent. Simulated microgravity had no significant influence on DNA DSB repair. Proliferation and cell cycle progression was not affected by radiation qualities examined in this study. Astrocytes expressed IL-6 and GFAP with constitutive NF-κB activity independent of radiation exposure. mRNA sequencing of X-irradiated astrocytes revealed downregulation of 66 genes involved in DNA damage response and repair, mitosis, proliferation and cell cycle regulation. Discussion: In conclusion, primary murine astrocytes are DNA repair proficient irrespective of radiation quality. Only minor gene expression changes were observed after X-ray exposure and reactivity was not induced. Co-culture of astrocytes with microglial cells, brain organoids or organotypic brain slice culture experiments might reveal whether astrocytes show a more pronounced radiation response in more complex network architectures in the presence of other neuronal cell types.


Asunto(s)
Astrocitos , FN-kappa B , Animales , Ratones , Astrocitos/metabolismo , Interleucina-6 , Iones , Encéfalo , ARN Mensajero , ADN
14.
Hum Brain Mapp ; 31(9): 1305-15, 2010 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-20127872

RESUMEN

After errors in reaction tasks, a sharp negative wave emerges in the event-related potential (ERP), the error (related) negativity (Ne or ERN). However, also after correct trials, an Ne-like wave is seen, called CRN or Nc, which is much smaller than the Ne. This study tested the hypothesis whether Ne and Nc reflect the same functional process, and whether this process is linked to online response control. For this purpose, independent component analysis (ICA) was utilized with the EEG data of two types of reaction tasks: a flanker task and a mental rotation task. To control for speed-accuracy effects, speed and accuracy instructions were balanced in a between subjects design. For both tasks ICA and dipole analysis revealed one component (Ne-IC) explaining most of the variance for the difference between correct and erroneous trials. The Ne-IC showed virtually the same features as the raw postresponse ERP, being larger for erroneous compared to correct trials and for the flanker than for the rotation task. In addition, it peaked earlier for corrected than for uncorrected errors. The results favor the hypothesis that Ne and Nc reflect the same process, which is modulated by response correctness and type of task. On the basis of the literature and the present results, we assume that this process induces online response control, which is much stronger in error than correct trials and with direct rather than indirect stimulus response mapping.


Asunto(s)
Mapeo Encefálico , Encéfalo/fisiología , Potenciales Evocados/fisiología , Electroencefalografía , Humanos
15.
Int J Psychophysiol ; 146: 217-224, 2019 12.
Artículo en Inglés | MEDLINE | ID: mdl-31669325

RESUMEN

Detecting errors is crucial for adapting one's own actions. Moreover, behavior is often optimized by adapting to maladaptive actions, i.e. errors. In this regard, recent studies and models of error monitoring point to an involvement of emotional states in error monitoring. A psychophysiological correlate of the latter is the error negativity or error-related negativity (Ne/ERN), reflecting partly the functional implementation of anterior cingulate cortex functions. In the present study, we aimed to test whether neurophysiological aspects of error monitoring can be altered by a relaxation technique, i.e. slow-paced breathing. Slow-paced breathing has been shown to increase cardiac vagal activity. According to the neurovisceral integration model, cardiac vagal activity is thought to be a marker of the effectiveness of executive functions. We tested the effect of slow-paced breathing on error monitoring, i.e. the Ne/ERN and behavioral adaptation in a modified flanker task, a cognitive task during which performance depends on executive control. The Ne was increased following slow-paced breathing compared to a passive control condition. Furthermore, behavioral results indicate that response variability decreased in the slow-paced breathing condition whereas overall performance remained constant. We conclude that slow-paced breathing improves the ability to focus on the task at hand. Thus, the error monitoring system is being supported in keeping the pace, i.e. tracking responses.


Asunto(s)
Sistema Nervioso Autónomo/fisiología , Ejercicios Respiratorios , Función Ejecutiva/fisiología , Giro del Cíngulo/fisiología , Desempeño Psicomotor/fisiología , Respiración , Adolescente , Adulto , Electroencefalografía , Femenino , Frecuencia Cardíaca/fisiología , Humanos , Masculino , Nervio Vago/fisiología , Adulto Joven
16.
Int J Pharm ; 565: 187-198, 2019 Jun 30.
Artículo en Inglés | MEDLINE | ID: mdl-31063837

RESUMEN

Various wet ball nanomilling-screening tools for poorly soluble APIs are available which differ in their milling principle, batch size and number of samples. Here, the transferability of results from screening (small to medium-scale) to pharmaceutical production (largescale) was investigated. Wet ball milling in a dual centrifuge (DC) (10-100 mg API, 40 samples in parallel) was used to identify stable nanoformulations. In addition different sized agitator bead mills were used for scale-up to industrial scales. DC-and small-scale agitator milling (AM) resulted in small and virtually identical API-particles. Additionally, similar API-particles were obtained using two different sized agitator bead mills (batch size 1.5 and 30 kg) and applying comparable specific grinding energies (SGE). The SGE used in the trials represents the grinding limit for this API-suspension. Using lower SGEs, AM results in larger API-particles. All used milling tools had no influence on the APIs crystal structure and wear of grinding media (Zr/Y) is low. The study confirmed the importance to choose the right formulation and process parameters, which positively affect grinding efficacy, particle size distribution and wear contamination. The excellent comparability of results obtained from DC-milling and AM significantly reduces the duration for successful and predictable formulation development.


Asunto(s)
Nanopartículas/química , Tecnología Farmacéutica , Centrifugación , Excipientes/química , Fenofibrato/química , Microscopía Electrónica de Rastreo , Nanopartículas/ultraestructura , Naproxeno/química , Polímeros/química , Tensoactivos/química
17.
Front Psychol ; 9: 1423, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30210379

RESUMEN

There is a vast amount of literature concerning the integration of action and cognition. Although this broad research area is of great interest for many disciplines like sports, psychology and cognitive neuroscience, only a few attempts tried to bring together different perspectives so far. Our goal is to provide a perspective to spark a debate across theoretical borders and integration of different disciplines via psychophysiology. In order to boost advances in this research field it is not only necessary to become aware of the different areas that are relevant but also to consider methodological aspects and challenges. We briefly describe the most relevant theoretical accounts to the question of how internal and external information processes or factors interact and, based on this, argue that research programs should consider the three dimensions: (a) dynamics of movements; (b) multivariate measures and; (c) dynamic statistical parameters. Only with an extended perspective on theoretical and methodological accounts, one would be able to integrate the dynamics of actions into theoretical advances.

18.
J Phys Chem B ; 110(25): 12351-9, 2006 Jun 29.
Artículo en Inglés | MEDLINE | ID: mdl-16800558

RESUMEN

Small-angle X-ray scattering (SAXS) and dynamic light scattering (DLS) measurements were accomplished on sodium glycodeoxycholate (NaGDC) aqueous electrolyte solutions as a function of NaGDC and NaCl concentrations with the aim to determine with satisfactory approximation the NaGDC micellar aggregate structure at a gross molecular level, assuming monodispersity. Different conditions of interparticle interactions by varying ionic strength (NaCl concentration from 0 to 0.70 M) and NaGDC concentration (from 0.02 to 0.10 M) were studied. Smeared scattering intensities and electron pair distance distribution functions, radii of gyration, and aggregate heights are in satisfactory agreement with the corresponding functions calculated using a 2(1) helix as model. It is formed by trimers, each one composed by three NaGDC and nine H2O molecules related by a 3-fold rotation axis, and can be described by a hollow cylinder, probably filled by water molecules, characterized by a conventional radius of 23.7 A and a trimer repeat along the helical axis of 3.6 A. The helix is considerably inhomogeneous since the volume of the cylinder occupied by NaGDC molecules is less than one-third of the total. On the other hand, calculations performed with the average radial electronic density of the helix without water molecules or totally filled by water molecules (a NaGDC/H2O molecular ratio of about 1/50) or by using a three-shell average radial electronic density, independently evaluated on absolute scale, do not show significant differences, thus supporting the helical model. The aggregate size increases for all the samples by increasing either the NaCl or NaGDC concentration. The NaGDC low concentration (0.02 M) samples with NaCl within the range 0.30-0.70 M are characterized by short cylindrical aggregates that do not give rise to sensible interference effects. This assertion is supported by the satisfactory fit between the observed apparent mean hydrodynamic radii and the calculated ones by means of the method of Ortega and Garcia de la Torre (J. Chem. Phys. 2003, 119, 9914), valid for rods with a length-to-diameter ratio > or = 0.1 in dilute solution (noninteracting rods). The NaGDC moderate concentration (0.10 M) samples with NaCl within the range 0.20-0.60 M are characterized by cylindrical aggregates that, in the presence of repulsive Coulombic interactions progressively more and more screened, produce interference effects, due to the hard-body repulsion and attractive forces, but the agreement between observed and calculated SAXS data is satisfactory. The results of the low and moderate NaGDC concentration samples seem to indicate that the aggregation number increase, produced by adding 0.10 M NaCl, is constant within an ionic strength range and occurs by the addition of oligomers formed by trimers. The samples with a variable NaGDC concentration (0.02-0.10 M) at a fixed and high NaCl concentration (0.6 M) contain cylindrical aggregates that give rise to an attractive term effect prevailing on the hard-body repulsive one. The same situation seems to occur in the NaGDC moderate concentration samples.


Asunto(s)
Ácido Glicodesoxicólico/química , Micelas , Luz , Modelos Moleculares , Estructura Molecular , Dispersión de Radiación
19.
Artículo en Alemán | MEDLINE | ID: mdl-17436560

RESUMEN

Scientific research on childhood constitutes a relatively new field. As we know today, there is no other period in our lives that more strongly forms us and our culture. Hence, it is surprising that in the past this viewpoint was completely different. Until medieval times, a child's life did not count for much, that is, as long as the child was not the beneficiary of an inheritance. And even if so, social relationships were businesslike, e.g. concerning marriage. J.-J. Rousseau (1712-1778) demonstrated the worthlessness of children even in his recognition of them: The nature of humans is neither good nor bad, and is hardly different from that of animals. Despite Rousseau's idealistic concept of education as a kind of identification process for the child, he put his own five children into the foundling hospital of Paris; he was bothered by them when writing. Up to the beginning of the 19th century, the value of a child was determined by his or her ability to work. In the years 1813 to 1814 in Great Britain, 130,000 out of 213,000 weavers were children under the age of 14. Children had to take part in breadwinning at an early age; their character was regarded as being like that of an immature adult (i. e., a small barbarian). Specific childlike needs were rarely met or even acknowledged by adults.


Asunto(s)
Maltrato a los Niños/historia , Cuidado del Niño/historia , Niño Abandonado/historia , Empleo/historia , Infanticidio/historia , Valores Sociales , Adolescente , Niño , Preescolar , Europa (Continente) , Femenino , Historia del Siglo XV , Historia del Siglo XVI , Historia del Siglo XVII , Historia del Siglo XVIII , Historia del Siglo XIX , Historia Antigua , Historia Medieval , Humanos , Lactante , Masculino , Estados Unidos
20.
Artículo en Alemán | MEDLINE | ID: mdl-17436561

RESUMEN

At the end of the 19th century, the Society for the Prevention of Cruelty to Children was founded in New York, after a barbarous case of neglect and abuse of a girl became public. From then on, children received more and more protection. Only in the 1950s were doctors in the USA bound by law to report cases of putative physical abuse to officials. In Sweden, physical punishment of children has been forbidden since 1989, and in Germany since 2001. The existence of sexual abuse of children had been a taboo subject for centuries, even though individual attempts to break that taboo were made--e. g., by S. Freud in the theory of seduction (Verführungstheorie). Only with the birth of the women's liberation movement in the early 1970s has public awareness arisen. Due to the work of J. Bowlby in the 1950s, it became clear that children of primates need more than air, water and food, namely a relationship between the child and an adult person (attachment). To what degree the basic needs of children are being fulfilled in Western societies today is still a controversial issue.


Asunto(s)
Maltrato a los Niños/historia , Cuidado del Niño/historia , Protección a la Infancia/historia , Apego a Objetos , Adolescente , Niño , Preescolar , Europa (Continente) , Historia del Siglo XIX , Historia del Siglo XX , Historia del Siglo XXI , Humanos , Lactante , Estados Unidos
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