Robustness and Enhancement of Neural Synchronization by Activity-Dependent Coupling

We study the synchronization of two model neurons coupled through a synapse having an activity-dependent strength. Our synapse follows the rules of Spike-Timing Dependent Plasticity (STDP). We show that this plasticity of the coupling between neurons produces enlarged frequency locking zones and results in synchronization that is more rapid and much more robust against noise than classical synchronization arising from connections with constant strength. We also present a simple discrete map model that demonstrates the generality of the phenomenon.Comment: 4 pages, accepted for publication in PR

Invariance and variability in interaction error-related potentials and their consequences for classification

© 2017 IOP Publishing Ltd. Objective. This paper discusses the invariance and variability in interaction error-related potentials (ErrPs), where a special focus is laid upon the factors of (1) the human mental processing required to assess interface actions (2) time (3) subjects. Approach. Three different experiments were designed as to vary primarily with respect to the mental processes that are necessary to assess whether an interface error has occurred or not. The three experiments were carried out with 11 subjects in a repeated-measures experimental design. To study the effect of time, a subset of the recruited subjects additionally performed the same experiments on different days. Main results. The ErrP variability across the different experiments for the same subjects was found largely attributable to the different mental processing required to assess interface actions. Nonetheless, we found that interaction ErrPs are empirically invariant over time (for the same subject and same interface) and to a lesser extent across subjects (for the same interface). Significance. The obtained results may be used to explain across-study variability of ErrPs, as well as to define guidelines for approaches to the ErrP classifier transferability problem

Performance breakdown effects dissociate from error detection effects in typing

Mistakes in skilled performance are often observed to be slower than correct actions. This error slowing has been associated with cognitive control processes involved in performance monitoring and error detection. A limited literature on skilled actions, however, suggests that preerror actions may also be slower than accurate actions. This contrasts with findings from unskilled, discrete trial tasks, where preerror performance is usually faster than accurate performance. We tested 3 predictions about error-related behavioural changes in continuous typing performance. We asked participants to type 100 sentences without visual feedback. We found that (a) performance before errors was no different in speed than that before correct key-presses, (b) error and posterror key-presses were slower than matched correct key-presses, and (c) errors were preceded by greater variability in speed than were matched correct key-presses. Our results suggest that errors are preceded by a behavioural signature, which may indicate breakdown of fluid cognition, and that the effects of error detection on performance (error and posterror slowing) can be dissociated from breakdown effects (preerror increase in variability). © 2013 © 2013 The Experimental Psychology Society

Rapid Processing of Both Reward Probability and Reward Uncertainty in the Human Anterior Cingulate Cortex

Reward probability and uncertainty are two fundamental parameters of decision making. Whereas reward probability indicates the prospect of winning, reward uncertainty, measured as the variance of probability, indicates the degree of risk. Several lines of evidence have suggested that the anterior cingulate cortex (ACC) plays an important role in reward processing. What is lacking is a quantitative analysis of the encoding of reward probability and uncertainty in the human ACC. In this study, we addressed this issue by analyzing the feedback-related negativity (FRN), an event-related potential (ERP) component that reflects the ACC activity, in a simple gambling task in which reward probability and uncertainty were parametrically manipulated through predicting cues. Results showed that at the outcome evaluation phase, while both win and loss-related FRN amplitudes increased as the probability of win or loss decreased, only the win-related FRN was modulated by reward uncertainty. This study demonstrates the rapid encoding of reward probability and uncertainty in the human ACC and offers new insights into the functions of the ACC

Abnormal resting-state cortical coupling in chronic tinnitus

<p>Abstract</p> <p>Background</p> <p>Subjective tinnitus is characterized by an auditory phantom perception in the absence of any physical sound source. Consequently, in a quiet environment, tinnitus patients differ from control participants because they constantly perceive a sound whereas controls do not. We hypothesized that this difference is expressed by differential activation of distributed cortical networks.</p> <p>Results</p> <p>The analysis was based on a sample of 41 participants: 21 patients with chronic tinnitus and 20 healthy control participants. To investigate the architecture of these networks, we used phase locking analysis in the 1–90 Hz frequency range of a minute of resting-state MEG recording. We found: 1) For tinnitus patients: A significant decrease of inter-areal coupling in the alpha (9–12 Hz) band and an increase of inter-areal coupling in the 48–54 Hz gamma frequency range relative to the control group. 2) For both groups: an inverse relationship (r = -.71) of the alpha and gamma network coupling. 3) A discrimination of 83% between the patient and the control group based on the alpha and gamma networks. 4) An effect of manifestation on the distribution of the gamma network: In patients with a tinnitus history of less than 4 years, the left temporal cortex was predominant in the gamma network whereas in patients with tinnitus duration of more than 4 years, the gamma network was more widely distributed including more frontal and parietal regions.</p> <p>Conclusion</p> <p>In the here presented data set we found strong support for an alteration of long-range coupling in tinnitus. Long-range coupling in the alpha frequency band was decreased for tinnitus patients while long-range gamma coupling was increased. These changes discriminate well between tinnitus and control participants. We propose a tinnitus model that integrates this finding in the current knowledge about tinnitus. Furthermore we discuss the impact of this finding to tinnitus therapies using Transcranial Magnetic Stimulation (TMS).</p

Neural Mechanisms of Human Perceptual Learning: Electrophysiological Evidence for a Two-Stage Process

Artículo de publicación ISIBackground: Humans and other animals change the way they perceive the world due to experience. This process has been labeled as perceptual learning, and implies that adult nervous systems can adaptively modify the way in which they process sensory stimulation. However, the mechanisms by which the brain modifies this capacity have not been sufficiently analyzed. Methodology/Principal Findings: We studied the neural mechanisms of human perceptual learning by combining electroencephalographic (EEG) recordings of brain activity and the assessment of psychophysical performance during training in a visual search task. All participants improved their perceptual performance as reflected by an increase in sensitivity (d') and a decrease in reaction time. The EEG signal was acquired throughout the entire experiment revealing amplitude increments, specific and unspecific to the trained stimulus, in event-related potential (ERP) components N2pc and P3 respectively. P3 unspecific modification can be related to context or task-based learning, while N2pc may be reflecting a more specific attentional-related boosting of target detection. Moreover, bell and U-shaped profiles of oscillatory brain activity in gamma (30-60 Hz) and alpha (8-14 Hz) frequency bands may suggest the existence of two phases for learning acquisition, which can be understood as distinctive optimization mechanisms in stimulus processing.This research was supported by CONICYT doctoral grant to C.M.H. and by an ECOS-Sud/CONICYT grant C08S02 and FONDECYT 1090612 grant to D.C. and F.A

Measuring the quality and quantity of professional intrapartum support: Testing a computerised systematic observation tool in the clinical setting

Background: Continuous support in labour has a significant impact on a range of clinical outcomes, though whether the quality and quantity of support behaviours affects the strength of this impact has not yet been established. To identify the quality and quantity of support, a reliable means of measurement is needed. To this end, a new computerised systematic observation tool, the &lsquo;SMILI' (Supportive Midwifery in Labour Instrument) was developed. The aim of the study was to test the validity and usability of the &lsquo;Supportive Midwifery in Labour Instrument' (SMILI) and to test the feasibility and acceptability of the systematic observation approach in the clinical intrapartum setting. Methods: Systematic observation was combined with a postnatal questionnaire and the collection of data about clinical processes and outcomes for each observed labour. The setting for the study was four National Health Service maternity units in Scotland, UK. Participants in this study were forty five midwives and forty four women. The SMILI was used by trained midwife observers to record labour care provided by midwives. Observations were undertaken for an average of two hours and seventeen minutes during the active first stage of labour and, in 18 cases, the observation included the second stage of labour. Content validity of the instrument was tested by the observers, noting the extent to which the SMILI facilitated the recording of all key aspects of labour care and interactions. Construct validity was tested through exploration of correlations between the data recorded and women's feelings about the support they received. Feasibility and usability data were recorded following each observation by the observer. Internal reliability and construct validity were tested through statistical analysis of the data. Results: One hundred and four hours of labour care were observed and recorded using the SMILI during forty nine labour episodes. Conclusion: The SMILI was found to be a valid and reliable instrument in the intrapartum setting in which it was tested. The study identified that the SMILI could be used to test correlations between the quantity and quality of support and outcomes. The systematic observational approach was found to be an acceptable and feasible method of enquiry

Brain Activity in Fairness Consideration during Asset Distribution: Does the Initial Ownership Play a Role?

Previous behavioral studies have shown that initial ownership influences individuals’ fairness consideration and other-regarding behavior. However, it is not entirely clear whether initial ownership influences the brain activity when a recipient evaluates the fairness of asset distribution. In this study, we randomly assigned the bargaining property (monetary reward) to either the allocator or the recipient in the ultimatum game and let participants of the study, acting as recipients, receive either disadvantageous unequal, equal, or advantageous unequal offers from allocators while the event-related potentials (ERPs) were recorded. Behavioral results showed that participants were more likely to reject disadvantageous unequal and equal offers when they initially owned the property as compared to when they did not. The two types of unequal offers evoked more negative going ERPs (the MFN) than the equal offers in an early time window and the differences were not modulated by the initial ownership. In a late time window, however, the P300 responses to division schemes were affected not only by the type of unequal offers but also by whom the property was initially assigned to. These findings suggest that while the MFN may function as a general mechanism that evaluates whether the offer is consistent or inconsistent with the equity rule, the P300 is sensitive to top-down controlled processes, into which factors related to the allocation of attentional resources, including initial ownership and personal interests, come to play

Pesan Moral Islami Dalam Film Le Grand Voyage Karya Ismael Ferroukhi: Sebuah Tinjauan Struktural

Kata kunci : Film, sastra, struktural, pesan moral, Islam.Film merupakan produk budaya yang tidak hanya menjadi hiburan di masyarakat, tetapi juga sebagai sarana penyampaian pesan moral yang mengarifkan. Salah satufilm Perancis yang dianggap menginspirasi adalah film berjudul Le grand voyageyang ditulis dan disutradarai oleh Ismaël Ferroukhi. Film ini bercerita tentang perjalanan seorang muslim keturunan Maroko dan anaknya yang bernama Reda.Mereka menempuh jarak ribuan mil dari Perancis menuju ke kota Makah untukmelaksanakan haji hanya dengan mengendarai sebuah mobil tua. Penelitian inibertujuan untuk mengetahui pesan moral islami apa saja yang terkandung dalamfilm Le grand voyage dan bagaimana pesan tersebut dimunculkan dalam film.Penelitian ini menggunakan teori Struktural untuk menjawab rumusan masalah.Penelitian ini merupakan penelitian kualitatif dengan menggunakan teknik studipustaka serta dokumentasi sebagai metode pengumpulan data, dan teknikdeskriptif dalam proses analisis data.Berdasarkan hasil penelitian ini, terdapat 13 pesan moral islami yang terkandungdalam film Le grand voyage. Semua pesan moral tersebut mengacu pada sebuahproses perbaikan moral dan spiritual antara manusia dengan manusia dan alam,serta antara manusia dengan TuhanPenulis menyarankan pada penelitian selanjutnya untuk meneliti film Le grandvoyage menggunakan pendekatan sosiologi sastra yang nantinya dapat mengupashal apa saja yang melatarbelakangi pembuatan film ini dan tujuan sebenarnyayang ingin dicapai oleh pembuat film Le grand voyage

Development of Large-Scale Functional Brain Networks in Children

Large-scale rewiring of brain circuits in children leads to emergence of hierarchical organization in the mature adult brain