Assessing processing-based measures of implicit statistical learning: Three serial reaction time experiments do not reveal artificial grammar learning

Implicit statistical learning, whereby predictable relationships between stimuli are detected without conscious awareness, is important for language acquisition. However, while this process is putatively implicit, it is often assessed using measures that require explicit reflection and conscious decision making. Here, we conducted three experiments combining an artificial grammar learning paradigm with a serial reaction time (SRT-AGL) task, to measure statistical learning of adjacent and nonadjacent dependencies implicitly, without conscious decision making. Participants viewed an array of six visual stimuli and were presented with a sequence of three auditory (nonsense words, Expt. 1; names of familiar objects, Expt. 2) or visual (abstract shapes, Expt. 3) cues and were asked to click on the corresponding visual stimulus as quickly as possible. In each experiment, the final stimulus in the sequence was predictable based on items earlier in the sequence. Faster responses to this predictable final stimulus compared to unpredictable stimuli would provide evidence of implicit statistical learning, without requiring explicit decision making or conscious reflection. Despite previous positive results (Christiansen et al. 2009 and Misyak et al. 2010) we saw little evidence of implicit statistical learning in any of the experiments, suggesting that in this case, these SRT-AGL tasks were not an effective measure implicit statistical learning

Radar Measurements of NHTSA’s Surrogate Vehicle ‘SS-V’

NHTSA seeks to objectively quantify the performance of forward-looking advanced technologies such as Crash Imminent Braking (CIB) and Dynamic Brake Support (DBS) on the test track. Since these evaluations are expected to result in collisions between the subject vehicle (SV) and a principal other vehicle (POV) positioned directly in front of it, safety necessitates that the POV be a surrogate. However, to insure the tests will provide an accurate assessment of the SV’s CIB and/or DBS capabilities, the surrogate must present as realistic. One way “realism” must be quantified involves a surrogate’s radar return characteristics. The tests described in this report were performed to assess the radar return characteristics of NHTSA’s Strikeable Surrogate Vehicle (SS_V), a test target visually similar to a small hatchback. This work was performed by Michigan Tech Research Institute (MTRI) and the University of Michigan’s Transportation Research Institute (UMTRI) on August 5, 2012 and October 11, 2012 under US DOT/NHTSA contracts DTNH22-12-P-0158 and DTNH22-12-P-01638, respectively. The tests performed indicate the SS_V is a viable surrogate for automotive safety tests where the SV approaches a POV from the tail-aspect

Auditory artificial grammar learning in macaque and marmoset monkeys.

Artificial grammars (AG) are designed to emulate aspects of the structure of language, and AG learning (AGL) paradigms can be used to study the extent of nonhuman animals' structure-learning capabilities. However, different AG structures have been used with nonhuman animals and are difficult to compare across studies and species. We developed a simple quantitative parameter space, which we used to summarize previous nonhuman animal AGL results. This was used to highlight an under-studied AG with a forward-branching structure, designed to model certain aspects of the nondeterministic nature of word transitions in natural language and animal song. We tested whether two monkey species could learn aspects of this auditory AG. After habituating the monkeys to the AG, analysis of video recordings showed that common marmosets (New World monkeys) differentiated between well formed, correct testing sequences and those violating the AG structure based primarily on simple learning strategies. By comparison, Rhesus macaques (Old World monkeys) showed evidence for deeper levels of AGL. A novel eye-tracking approach confirmed this result in the macaques and demonstrated evidence for more complex AGL. This study provides evidence for a previously unknown level of AGL complexity in Old World monkeys that seems less evident in New World monkeys, which are more distant evolutionary relatives to humans. The findings allow for the development of both marmosets and macaques as neurobiological model systems to study different aspects of AGL at the neuronal level

Estimating Turbulence Distribution over a Heterogeneous Path Using Time‐lapse Imagery from Dual Cameras

Knowledge of turbulence distribution along an experimental path can help in effective turbulence compensation and mitigation. Although scintillometers are traditionally used to measure the strength of turbulence, they provide a path-integrated measurement and have limited operational ranges. A technique to profile turbulence using time-lapse imagery of a distant target from spatially separated cameras is presented here. The method uses the turbulence induced differential motion between pairs of point features on a target, sensed at a single camera and between cameras to extract turbulence distribution along the path. The method is successfully demonstrated on a 511 m almost horizontal path going over half concrete and half grass. An array of Light-Emitting Diodes (LEDs) of non-uniform separation is imaged by a pair of cameras, and the extracted turbulence profiles are validated against measurements from 3D sonic anemometers placed along the path. A short-range experiment with a heat source to create local turbulence spike gives good results as well. Because the method is phase-based, it does not suffer from saturation issues and can potentially be applied over long ranges. Although in the present work, a cooperative target has been used, the technique can be used with non-cooperative targets. Application of the technique to images collected over slant paths with elevated targets can aid in understanding the altitude dependence of turbulence in the surface layer

EEG potentials associated with artificial grammar learning in the primate brain

AbstractElectroencephalography (EEG) has identified human brain potentials elicited by Artificial Grammar (AG) learning paradigms, which present participants with rule-based sequences of stimuli. Nonhuman animals are sensitive to certain AGs; therefore, evaluating which EEG Event Related Potentials (ERPs) are associated with AG learning in nonhuman animals could identify evolutionarily conserved processes. We recorded EEG potentials during an auditory AG learning experiment in two Rhesus macaques. The animals were first exposed to sequences of nonsense words generated by the AG. Then surface-based ERPs were recorded in response to sequences that were ‘consistent’ with the AG and ‘violation’ sequences containing illegal transitions. The AG violations strongly modulated an early component, potentially homologous to the Mismatch Negativity (mMMN), a P200 and a late frontal positivity (P500). The macaque P500 is similar in polarity and time of occurrence to a late EEG positivity reported in human AG learning studies but might differ in functional role

Inhibition of Nitric Oxide Inhibition of Nitric Oxide Synthase Does Not Alter Dynamic Cerebral Autoregulation in Humans

The aim of this study was to determine whether inhibition of nitric oxide synthase (NOS) alters dynamic cerebral autoregulation in humans. Beat-to-beat blood pressure (BP) and cerebral blood flow (CBF) velocity (transcranial Doppler) were measured in eight healthy subjects in the supine position and during 60° head-up tilt (HUT). NOS was inhibited by intravenous N G-monomethyl-L-arginine (L-NMMA) infusion. Dynamic cerebral autoregulation was quantified by transfer function analysis of beat-to-beat changes in BP and CBF velocity. Pressor effects of L-NMMA on cerebral hemodynamics were compared with those of phenylephrine infusion. In the supine position, L-NMMA increased mean BP from 83 ± 3 to 94 ± 3 mmHg (P \u3c 0.01). However, CBF velocity remained unchanged. Consequently, cerebrovascular resistance index (CVRI) increased by 15% (P \u3c 0.05). BP and CBF velocity variability and transfer function gain at the low frequencies of 0.07-0.20 Hz did not change with L-NMMA infusion. Similar changes in mean BP, CBF velocity, and CVRI were observed after phenylephrine infusion, suggesting that increase in CVRI after L-NMMA was mediated myogenically by increase in arterial pressure rather than a direct effect of cerebrovascular NOS inhibition. During baseline tilt without L-NMMA, steady-state BP increased and CBF velocity decreased. BP and CBF velocity variability at low frequencies increased in parallel by 277% and 217%, respectively (P \u3c 0.05). However, transfer function gain remained unchanged. During tilt with L-NMMA, changes in steady-state hemodynamics and BP and CBF velocity variability as well as transfer gain and phase were similar to those without L-NMMA. These data suggest that inhibition of tonic production of NO does not appear to alter dynamic cerebral autoregulation in humans

Nitric Oxide Synthase Inhibition Does Not Affect Regulation of Muscle Sympathetic Nerve Activity During Head-Up Tilt

To test the hypothesis that systemic inhibition of nitric oxide (NO) synthase does not alter the regulation of sympathetic outflow during head-up tilt in humans, in eight healthy subjects NO synthase was blocked by intravenous infusion of NG-monomethyl-L-arginine (L-NMMA). Blood pressure, heart rate, cardiac output, total peripheral resistance (TPR), and muscle sympathetic nerve activity (MSNA) were recorded in the supine position and during 60° head-up tilt. In the supine position, infusion of L-NMMA increased blood pressure, via increased TPR, and inhibited MSNA. However, the increase in MSNA evoked by head-up tilt during L-NMMA infusion (change in burst rate: 24 ± 4 bursts/min; change in total activity: 209 ± 36 U/min) was similar to that during head-up tilt without L-NMMA (change in burst rate: 23 ± 4 bursts/min; change in total activity: 251 ± 52 U/min, n = 6, all P \u3e 0.05). Moreover, changes in TPR and heart rate during head-up tilt were virtually identical between the two conditions. These results suggest that systemic inhibition of NO synthase with L-NMMA does not affect the regulation of sympathetic outflow and vascular resistance during head-up tilt in humans

Surface Characterisation of Kolk-Boils within Tidal Stream Environments Using UAV Imagery

Funding: This work was funded by the Bryden Centre project, supported by the European Union’s IN- TERREG VA Programme, and managed by the Special EU Programmes Body (SEUPB). The views and opinions expressed in this paper do not necessarily reflect those of the European Commission or SE- UPB. Aspects of this research were also funded by a Royal Society Research Grant [RSG\R1\180430], the NERC VertIBase project [NE/N01765X/1] and the UK Department for Business, Energy and Industrial Strategy’s offshore energy Strategic Environmental Assessment programme. Data Availability Statement The data underlying this article will be shared on reasonable request to the corresponding author. Acknowledgments We gratefully acknowledge the support of Julien Martin, colleagues at Marine Scotland Science and the crew and scientists of the MRV Scotia 2016 and 2018 cruises (particularly Chief Scientists Eric Armstrong and Adrian Tait). We also acknowledge the work contributed by ERI interns: Gael Gelis and Martin Forestier.Peer reviewedPublisher PD

Using Unmanned Aerial Vehicle (UAV) Imagery to Characterise Pursuit-Diving Seabird Association With Tidal Stream Hydrodynamic Habitat Features

Acknowledgments We gratefully acknowledge the support of colleagues at Marine Scotland Science, the crew and scientists of the MRV Scotia 2018 cruise (particularly Chief Scientist Adrian Tait) and ERI interns: Gael Gelis and Martin Forestier. We gratefully acknowledge the constructive comments from reviewers. Finally, we also want to thank Ella Benninghaus for providing the auk illustrations used within the paper. Funding This work was funded by the Bryden Centre project, supported by the European Union’s INTERREG VA Programme, and managed by the Special EU Programmes Body (SEUPB). The views and opinions expressed in this paper do not necessarily reflect those of the European Commission or the Special EU Programmes Body (SEUPB). Aspects of this research were also funded by a Royal Society Research Grant [RSG\R1\180430], the NERC VertIBase project [NE/N01765X/1], the UK Department for Business, Energy, and Industrial Strategy’s offshore energy Strategic Environmental Assessment programme and EPSRC Supergen ORE Hub [EP/S000747/1].Peer reviewedPublisher PD

Quantitative investigation of the short-range magnetic correlations in candidate quantum spin liquid NaYbO2_2

We present a neutron diffraction study of NaYbO$_2$, a candidate quantum spin liquid compound hosting a geometrically frustrated triangular lattice of magnetic Yb$^{3+}$ ions. We observe diffuse magnetic scattering that persists to at least 20 K, demonstrating the presence of short-range magnetic correlations in this system up to a relatively high energy scale. Using reverse Monte Carlo and magnetic pair distribution function analysis, we confirm the predominant antiferromagnetic nature of these correlations and show that the diffuse scattering data can be well described by noninteracting layers of XY spins on the triangular lattice. We rule out Ising spins and short-range-ordered stripe or 120$^{\circ}$ phases as candidate ground states of NaYbO$_2$. These results are consistent with a possible QSL ground state in NaYbO$_2$ and showcase the benefit of combined reciprocal- and real-space analysis of materials with short-range magnetic correlations