76,486 research outputs found
Gli avverbi monolessicali di luogo, tempo e maniera nelle lingue indoeuropee antiche. Verso un approccio tipologico
No full textArticles and Quantifiers in the Mediterranean Languages: a Typological-Diachronic Analysis
No full textGradualness in contact-induced grammatical replication: the case of the Abstract Possession construction in the Circum-Mediterranean area
No full textIt is widely appreciated that the linguistic category of possession does not reduce to any single, familiar value, such as ownership. A moment’s thought reveals the extraordinary variety of the relationships coded by possessive constructions. (Langacker 1991: 169)In this paper we investigate the emergence, the diachronic spread and the resulting areal distribution of the so-called Abstract Possession construction in the Circum-Mediterranean area. In this construction, grammatical means typically used to convey concrete possession are recruited to express feelings and other abstract states. We explore the dynamics through which this construal gradually extended both in space and time with reference to a well-defined grammaticalization area (Kuteva 2000). We take into account cases of contact-induced grammatical replication and we show that different degrees of grammaticalization correlate with geographical factors. We also address some issues pertaining to the field of lexical typology and explore the privileged semantic paths along which the construction was extended in different languages. Finally, on the basis of our data we provide some insights into the functional characterization of the domain of abstract possession
A novel expression cassette for the efficient visual selection of transformed tissues in florists' chrysanthemum (Chrysanthemum morifolium Ramat.).
No full textConstructs carrying visual reporter genes coupled with efficient promoters could facilitate the process of identification and selection of stable transformants in recalcitrant crops. Here, a novel construct utilizing a ribulose-1,5-bisphosphate carboxylase (RbcS) promoter combined with the green fluorescent protein (GFP) reporter gene to initiate very high expression of GFP in florist's chrysanthemum (Chrysanthemum morifolium Ramat.) was described. Based on this expression cassette, a new regeneration protocol using leaf discs as explants was developed for the Agrobacterium-mediated transformation of Chrysanthemum genotype ‘1581’, and a transformation efficiency of 7% was obtained. The expression of two different GFP constructs targeted to either cytosol or plastids was compared in transgenic lines. Both GFP constructs were expressed at such a high level that the green fluorescence dominated red fluorescence in the leaf tissues, allowing easy observation and microdissection of transformed tissues even without a GFP filter. Under normal light, plants with GFP targeted to plastids had a light green phenotype deriving from the high GFP expression. Quantitative reverse transcriptional PCR analysis showed that the plastid targeted construct with intron had significantly higher steady state transcript levels of GFP mRNA. This novel expression cassette may allow direct visual selection of transformed tissues independent of antibiotic selection in a wide range of plant specie
After Effects of Cerebellar Continuous Theta Burst Stimulation on Reflexive Saccades and Smooth Pursuit in Humans
No full textThe use of cerebellar repetitive transcranial magnetic stimulation has been attempted for perturbing reflexive and voluntary eye movements, but discrepancies are seen between the results of distinct studies possibly due to the different stimulation sites, intensities, and paradigms. We describe the after effects of 20 and 40 s continuous Theta Burst Stimulation (cTBS) as compared to sham stimulation, applied over the lateral cerebellar vermis and paravermis on Reflexive Saccades (RS) and Smooth Pursuit (SP) eye movements, recorded in the 30 min following stimulation. The experiments were carried out in eight healthy volunteers, and eye movements were recorded monocularly with video-oculography. The 40 s cTBS significantly increased the amplitude of ipsilateral RS and the acceleration of the ipsilateral SP, and this effect was detectable all over the 30-min recording period; 40 s cTBS did not modify the other parameters, namely the peak velocity, the duration and the latency of RS, and the latency and the velocity of SP. The 20 s cTBS was ineffective on all RS and SP parameters. Finally, we detected a significant quite-linear reduction of RS peak velocity over time, but this was independent from cTBS and was probably caused by fatigue. The effects of 40 s cTBS in our experiments mimic the disorder of ocular motility in Wallenberg's syndrome and could result from functional impairment of cerebellopontine pathways. This effect lasts 30 min at least, and can provide a useful framework for adaptive ocular motor studies
A new tool for investigating the functional testing of the VOR
No full textPeripheral vestibular function may be tested quantitatively, by measuring the gain of the angular vestibulo-ocular reflex (aVOR), or functionally, by assessing how well the aVOR performs with respect to its goal of stabilizing gaze in space and thus allow to acquire visual information during the head movement. In recent years, several groups have developed clinical and quantitative approaches to functional testing of the vestibular system based on the ability to identify an optotype briefly displayed on screen during head rotations.Although the proposed techniques differ in terms of the parameters controlling the testing paradigm, no study has thus far dealt with understanding the role of such choices in determining the effectiveness and reliability of the testing approach. Moreover, recent work has shown that peripheral vestibular patients may produce corrective saccades during the head movement (covert saccades), yet the role of these eye movements towards reading ability during head rotations is not yet understood. Finally, no study has thus far dealt with measuring the true performance of their experimental setups, which is nonetheless likely to be crucial information for understanding the effectiveness of functional testing approaches. Thus we propose a new software and hardware research tool allowing the combined measurement of eye and head movements, together with the timing of the optotype on screen, during functional testing of the VOR based on the Head Impulse Test (HIT). The goal of such tool is therefore that of allowing functional testing of the VOR while collecting the experimental data necessary to understand, for instance, a) the effectiveness of the covert saccades strategy towards image stabilization, b) which experimental parameters are crucial for optimizing the diagnostic power of the functional testing approach, and c) which conditions lead to a successful reading or an error trial
A Multihead Attention Deep Learning Algorithm to Detect Amblyopia Using Fixation Eye Movements
No full textObjective: To develop an attention-based deep learning (DL) model based on eye movements acquired during a simple visual fixation task to detect amblyopic subjects across different types and severity from controls. Design: An observational study. Subjects: We recruited 40 controls and 95 amblyopic subjects (anisometropic = 32; strabismic = 29; and mixed = 34) at the Cleveland Clinic from 2020 to 2024. Methods: Binocular horizontal and vertical eye positions were recorded using infrared video-oculography during binocular and monocular viewing. Amblyopic subjects were classified as those without nystagmus (n = 42) and those with nystagmus with fusion maldevelopment nystagmus (FMN) or nystagmus that did not meet the criteria of FMN or infantile nystagmus syndrome (n = 53). A multihead attention-based transformer encoder model was trained and cross-validated on deblinked and denoised eye position data acquired during fixation. Main Outcome Measures: Detection of amblyopia across types (anisometropia, strabismus, or mixed) and severity (treated, mild, moderate, or severe) and subjects with and without nystagmus was evaluated with area under the receiver-operator characteristic curves, area under the precision–recall curve (AUPRC), and accuracy. Results: Area under the receiver-operator characteristic curves for classification of subjects per type were 0.70 ± 0.16 for anisometropia (AUPRC: 0.72 ± 0.08), 0.78 ± 0.15 for strabismus (AUPRC: 0.81 ± 0.16), and 0.80 ± 0.13 for mixed (AUPRC: 0.82 ± 0.15). Area under the receiver-operator characteristic curves for classification of amblyopia subjects per severity were 0.77 ± 0.12 for treated/mild (AUPRC: 0.76 ± 0.18), and 0.78 ± 0.09 for moderate/severe (AUPRC: 0.79 ± 0.16). Th area under the receiver-operator characteristic curve for classification of subjects with nystagmus was 0.83 ± 0.11 (AUPRC: 0.81 ± 0.18), and the area under the receiver-operator characteristic curve for those without nystagmus was 0.75 ± 0.15 (AUPRC: 0.76 ± 0.09). Conclusions: The multihead transformer DL model classified amblyopia subjects regardless of the type, severity, and presence of nystagmus. The model's ability to identify amblyopia using eye movements alone demonstrates the feasibility of using eye-tracking data in clinical settings to perform objective classifications and complement traditional amblyopia evaluations. Financial Disclosure(s): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article
Interaural Translational VOR: Suppression, Enhancement, and Cognitive Control
No full textWe investigated the influence of cognitive factors on the early response of the interaural translational vestibuloocular reflex (tVOR) in six normal subjects. Variables were prior knowledge of direction of head motion and the position of the fixation target relative to the head [head-fixed (HF) or space-fixed (SF)]. A manually driven device provided a step-like head translation (∼35 mm distance, peak acceleration, 0.6-1.3 g). Subjects looked at the SF or HF target located 15 cm in front of their heads in otherwise complete darkness. The testing paradigms were: random interleaving of SF and HF targets with unknown direction of head movement, known target location with random head direction (SFR or HFR), and known target location with known head direction (SFP or HFP). Timing was always unpredictable. A "gain" of the slow phase was calculated with respect to ideal performance (maintained fixation of the SF target, recorded/ideal eye velocity computed at time of peak head velocity). At such times, there were no significant differences in gain between HF and SF trials in the random condition; the average gain was ∼36% of ideal. On the other hand, responses in the SFR and HFR conditions differed as early as 20 ms after the head began moving. Average gain was higher (0.43 ± 0.11 vs. 0.34 ±0.14; means ± SD, P < 0.05) for each subject in the SFR than the HFR condition. For SFP and HFP, the responses differed from the onset of head motion. Average slow-phase gain was higher (0.49 ± 0.12 vs. 0.31 ± 0.12, P < 0.02) for each subject in SFP than in HFP. The timing of corrective saccades during the IVOR was also influenced by cognitive factors. Visual error signals seemed to be more important for triggering saccades in HF trials, whereas preprogramming, probably based on labyrinthine information, seemed to be more important in SF trials. Simulations showed that the changes in slow-phase gain with cognition could be reproduced with simple parametric adjustments of the gain of activity from otolith afferents and suggest that higher-level cognitive control of the VOR could occur as early as the synapse of peripheral afferents on neurons in the vestibular nuclei, either directly from higher level centers or via the cerebellum. In sum, the tVOR-both in its slow-phase response and the saccadic corrections-is subject to "higher-level" cognitive influences including knowledge of where the line of sight must point during head motion and the impending direction of head motion
A role for NMDAR-dependent cerebellar plasticity in adaptive control of saccades in humans
No full textBackground Saccade pulse amplitude adaptation is mediated by the dorsal cerebellar vermis and fastigial nucleus. Long-term depression at the parallel fibre-Purkinjie cell synapses has been suggested to provide a cellular mechanism for the corresponding learning process. The mechanisms and sites of this plasticity, however, are still debated. Objective To test the role of cerebellar plasticity phenomena on adaptive saccade control. Methods We evaluated the effect of continuous theta burst stimulation (cTBS) over the posterior vermis on saccade amplitude adaptation and spontaneous recovery of the initial response. To further identify the substrate of synaptic plasticity responsible for the observed adaptation impairment, subjects were pre-treated with memantine, an N-methyl-D-aspartate receptor (NMDAR) antagonist. Results Amplitude adaptation was altered by cTBS, suggesting that cTBS interferes with cerebellar plasticity involved in saccade adaptation. Amplitude adaptation and spontaneous recovery were not affected by cTBS when recordings were preceded by memantine administration. Conclusion The effects of cTBS are NMDAR-dependent and are likely to involve long-term potentiation or long-term depression at specific synaptic connections of the granular and molecular layer, which could effectively take part in cerebellar motor learning
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