A Usage-Based Model of Early Grammatical Development

The representations and processes yield-ing the limited length and telegraphic style of language production early on in acqui-sition have received little attention in ac-quisitional modeling. In this paper, we present a model, starting with minimal lin-guistic representations, that incrementally builds up an inventory of increasingly long and abstract grammatical representations (form+meaning pairings), in line with the usage-based conception of language ac-quisition. We explore its performance on a comprehension and a generation task, showing that, over time, the model bet-ter understands the processed utterances, generates longer utterances, and better ex-presses the situation these utterances in-tend to refer to.

Localisation Of The Subthalamic Nucleus In Parkinson’s Disease with Neural Beta and Gamma Activity of Local Field Potentials

Introduction: To refine the MRI-based target during DBS surgery, microelectrode recordings (MER) are often performed to detect target-specific single unit activity. This requires additional recording time and increases the risk for haemorrhage. In the future it may therefore be relevant to be able to determine the implantable lead's position based on local field potential (LFP) recordings from the lead itself which reflect activity of a larger neural population. This study aims to evaluate the nature of oscillatory activity in the subthalamic nucleus (STN) by means of intraoperative LFP-recordings, its relationship with microelectrode recordings and its potential use to locate the STN and its sensorimotor sub-area in patients with Parkinson’s disease during deep brain stimulation (DBS) surgery.Methods: 25 patients with Parkinson’s disease are included in this study. MER and LFPs are recorded every 0.5 mm from multiple microelectrodes during DBS surgery in 48 STNs. A novel optimization approach to map the measurement points on an atlas STN based on the MER properties is used to enable a detailed spatial representation of these points. Power and coherence in different LFP frequencies at all points are assessed in reference to the point's location inside or outside the STN and its sensorimotor sub-area.Results: Coherence between LFPs and the envelope of spiking activity significantly increases when entering the STN. There is also a pronounced increase in the LFP power in the gamma band, which persists throughout the entire STN in 100% of the cases. In 70% of the cases LFPs have a significantly higher power in the high beta frequency band in the sensorimotor STN, defined by the mapping algorithm, compared to the non-sensorimotor STN.Conclusions: LFP gamma oscillations provide a useful tool for locating the STN intraoperatively and LFP beta oscillations can become useful to discriminate the sensorimotor area within the STN

Temporal evolution of event-related desynchronization in acute stroke: A pilot study

Objective\ud Assessment of event-related desynchronization (ERD) may assist in predicting recovery from stroke and rehabilitation, for instance in BCI applications. Here, we explore the temporal evolution of ERD during stroke recovery.\ud \ud Methods\ud Ten stroke patients and eleven healthy controls were recruited to participate in a hand movement task while EEG was being recorded. Four measurements were conducted in eight patients within four months. We quantified changes of ERD using a modulation strength measure, Sm, which represents an area and amplitude of ERD.\ud \ud Results\ud 7/8 patients showed good recovery. Absence-or-reduction of ipsilesional modulation was initially found in stroke patients but not in the healthy controls. In the patient group, two evolutions were found in 6/8 patients: a significant increase in ipsilesional Sm; and a decreasing trend in contralesional Sm. In the only non-recovery patient, absence of ipsilesional modulation was observed, while his contralesional Sm increased with time after stroke.\ud \ud Conclusion\ud The two evolutions presumably reflect the reorganization of brain networks and functional recovery after acute stroke. The significant increase of ipsilesional Sm in patients with a good recovery suggests an important role of this hemisphere during recov

Avoiding Internal Capsule Stimulation With a New Eight-Channel Steering Deep Brain Stimulation Lead

Objective: Novel deep brain stimulation (DBS) lead designs are currently entering the market, which are hypothesized to provide a way to steer the stimulation field away from neural populations responsible for side effects and towards populations responsible for beneficial effects. The objective of this study is to assess the performances of a new eight channel steering-DBS lead and compare this with a conventional cylindrical contact (CC) lead. Approach: The two leads were evaluated in a finite element electric field model combined with multicompartment neuron and axon models, representing the internal capsule (IC) fibers and subthalamic nucleus (STN) cells. We defined the optimal stimulation setting as the configuration that activated the highest percentage of STN cells, without activating any IC fibers. With this criterion, we compared monopolar stimulation using a single contact of the steering-DBS lead and CC lead, on three locations and four orientations of the lead. In addition, we performed a current steering test case by dividing the current over two contacts with the steering-DBS lead in its worst-case orientation. Main Results: In most cases, the steering-DBS lead is able to stimulate a significantly higher percentage of STN cells compared to the CC lead using single contact stimulation or using a two contact current steering protocol when there is approximately a 1 mm displacement of the CC lead. The results also show that correct placement and orientation of the lead in the target remains an important aspect in achieving the optimal stimulation outcome. Significance Currently, clinical trials are set up in Europe with a similar design as the steering-DBS lead. Our results illustrate the importance of the orientation of the new steering-DBS lead in avoiding side effects induced by stimulation of IC fibers. Therefore, in clinical trials sufficient attention should be paid to implanting the steering DBS-lead in the most effective orientation

Midterm survival after endovascular repair of intact abdominal aortic aneurysms is improving over time

OBJECTIVE: There is a growing body of literature raising concerns over the long-term durability of endovascular repair (EVAR) for abdominal aortic aneurysms (AAA), suggesting that long-term outcomes may be better after open AAA repair. However, the data investigating these long-term outcomes largely originate from early in the endovascular era and therefore do not account for increasing clinical experience and technological improvements. We investigated whether four-year outcomes after EVAR and open repair have improved over time. METHODS: We identified all EVARs and open repairs for intact infrarenal AAA within the Vascular Quality Initiative database (2003-2018). We then stratified patients by procedure year into treatment cohorts of four years: 2003-2006, 2007-2010, 2011-2014, and 2015-2018. We used Kaplan-Meier analysis and Cox proportional hazards models to assess whether the survival following EVAR or open repair changed over time. Additionally, we propensity-matched EVAR and open repairs for each time cohort, to investigate whether the relative survival benefit of EVAR over open repair changed over time. RESULTS: We included 42,293 EVARs (increasing from 549 performed between 2003-2006 to 25,433 between 2015-2018) and 5,189 open AAA repairs (increasing from 561 to 2,306). Four-year survival increased for the periods 2003-2006, 2007-2010, 2011-2014, and 2015-2018 following both EVAR (76.6% vs. 79.7% vs. 83.5% vs. 87.3%; P<.001) and open repair (82.2% vs. 85.8% vs. 87.7% vs. 88.9%; P=.026). After risk-adjustment, compared to 2003-2006, hazard of mortality up to four years after EVAR was lower in those performed between 2011-2014 (hazard ratio [HR]: 0.72; 95% confidence interval [CI]: 0.59-0.87; P=.001) and for those performed between 2015-2018 (HR: 0.56; 95%CI: 0.46-0.68; P<.001). In contrast, the risk-adjusted hazard of mortality was similar between open repair cohorts (2011-2014: HR: 0.81 [95%CI: 0.61-1.08; P=.15]; and 2015-2018: HR: 0.86 [95%CI: 0.64-1.17; P=.34]). Finally, in matched EVAR and open repairs, there was no difference in mortality in the first three cohorts, while the hazard of mortality was lower for the 2015-2018 cohort (HR: 0.65; 95%CI: 0.51-0.84; P=.001). CONCLUSION: Four-year survival following EVAR improved in patients treated in more recent years but not following open repair. This finding suggests that mid-term outcomes following EVAR are improving, perhaps due to technological improvements and increased experience, information that should be considered by surgeons and policymakers alike when evaluating the value of contemporary EVAR and open AAA repair