Bigrams and the richness of the stimulus.

Abstract Recent challenges to Chomsky's poverty of the stimulus thesis for language acquisition suggest that children's primary data may carry "indirect evidence" about linguistic constructions despite containing no instances of them. Indirect evidence is claimed to suffice for grammar acquisition, without need for innate knowledge. This article reports experiments based on those o

Contrast-enhanced MR Imaging versus Contrast-enhanced US: A Comparison in Glioblastoma Surgery by Using Intraoperative Fusion Imaging

Purpose To compare contrast material enhancement of glioblastoma multiforme (GBM) with intraoperative contrast-enhanced ultrasonography (US) versus that with preoperative gadolinium-enhanced T1-weighted magnetic resonance (MR) imaging by using real-time fusion imaging. Materials and Methods Ten patients with GBM were retrospectively identified by using routinely collected, anonymized data. Navigated contrast-enhanced US was performed after intravenous administration of contrast material before tumor resection. All patients underwent tumor excision with navigated intraoperative US guidance with use of fusion imaging between real-time intraoperative US and preoperative MR imaging. With use of fusion imaging, glioblastoma contrast enhancement at contrast-enhanced US (regarding location, morphologic features, margins, dimensions, and pattern) was compared with that at gadolinium-enhanced T1-weighted MR imaging. Results Fusion imaging for virtual navigation enabled matching of real-time contrast-enhanced US scans to corresponding coplanar preoperative gadolinium-enhanced T1-weighted MR images in all cases, with a positional discrepancy of less than 2 mm. Contrast enhancement of gadolinium-enhanced T1-weighted MR imaging and contrast-enhanced US was superimposable in all cases with regard to location, margins, dimensions, and morphologic features. The qualitative analysis of contrast enhancement pattern demonstrated a similar distribution in contrast-enhanced US and gadolinium-enhanced T1-weighted MR imaging in nine patients: Seven lesions showed peripheral inhomogeneous ring enhancement, and two lesions showed a prevalent nodular pattern. In one patient, the contrast enhancement pattern differed between the two modalities: Contrast-enhanced US showed enhancement of the entire bulk of the tumor, whereas gadolinium-enhanced T1-weighted MR imaging demonstrated peripheral contrast enhancement. Conclusion Glioblastoma contrast enhancement with contrast-enhanced US is superimposable on that provided with preoperative gadolinium-enhanced T1-weighted MR imaging regarding location, margins, morphologic features, and dimensions, with a similar enhancement pattern in most cases. Thus, contrast-enhanced US is of potential use in the surgical management of GBM

Compensating control participants when the intervention is of significant value: experience in Guatemala, India, Peru and Rwanda

The Household Air Pollution Intervention Network (HAPIN) trial is a randomised controlled trial in Guatemala, India, Peru and Rwanda to assess the health impact of a clean cooking intervention in households using solid biomass for cooking. The HAPIN intervention—a liquefied petroleum gas (LPG) stove and 18-month supply of LPG—has significant value in these communities, irrespective of potential health benefits. For control households, it was necessary to develop a compensation strategy that would be comparable across four settings and would address concerns about differential loss to follow-up, fairness and potential effects on household economics. Each site developed slightly different, contextually appropriate compensation packages by combining a set of uniform principles with local community input. In Guatemala, control compensation consists of coupons equivalent to the LPG stove’s value that can be redeemed for the participant’s choice of household items, which could include an LPG stove. In Peru, control households receive several small items during the trial, plus the intervention stove and 1 month of fuel at the trial’s conclusion. Rwandan participants are given small items during the trial and a choice of a solar kit, LPG stove and four fuel refills, or cash equivalent at the end. India is the only setting in which control participants receive the intervention (LPG stove and 18 months of fuel) at the trial’s end while also being compensated for their time during the trial, in accordance with local ethics committee requirements. The approaches presented here could inform compensation strategy development in future multi-country trials

Prediction of the timing and the rhythm of the parkinsonian subthalamic nucleus neural spikes using the local field potentials

In this paper, we discuss the use of a nonlinear cascade model to predict the subthalamic nucleus spike activity from the local field potentials recorded in the motor area of the nucleus of Parkinsons disease patients undergoing deep brain stimulation. We use a segment of appropriately selected and processed data recorded from five nuclei to acquire the information of the spike timing and rhythm of a single neuron and estimate the model parameters. We then use the rest of each recording to assess the models accuracy in predicting spike timing, rhythm, and interspike intervals. We show that the cumulative distribution function (CDF) of the predicted spikes remains inside the 95 confidence interval of the CDF of the recorded spikes. By training the model appropriately, we prove its ability to provide quite accurate predictions for multiple-neuron recordings as well, and we establish its validity as a simple yet biologically plausible model of the intranuclear spike activity recorded from Parkinsons disease patients. © 2012 IEEE

Toward relating the subthalamic nucleus spiking activity to the local field potentials acquired intranuclearly

Studies on neurophysiological correlates of the functional magnetic resonance imaging (fMRI) signals reveal a strong relationship between the local field potential (LFP) acquired invasively and metabolic signal changes in fMRI experiments. Most of these studies failed to reveal an analogous relationship between metabolic signals and the spiking activity. That would allow for the prediction of the neural activity exclusively from the fMRI signals. However, the relationship between fMRI signals and spiking activity can be inferred indirectly provided that the LFPs can be used to predict the spiking activity of the area. Until now, only the LFP-spike relationship in cortical areas has been examined. Herein, we show that the spiking activity can be predicted by the LFPs acquired in a deep nucleus, namely the subthalamic nucleus (STN), using a nonlinear cascade model. The model can reproduce the spike patterns inside the motor area of the STN that represent information about the motor plans. Our findings expand the possibility of further recruiting non-invasive neuroimaging techniques to understand the activity of the STN and predict or even control movement. © 2011 IOP Publishing Ltd

Stereotactic biopsy in the era of advanced neuroimaging. Does the minimal therapeutic gain justify its current wide use?

Objective: This study reviewed the contribution of stereotactic brain biopsy in the management and final outcome of a series of patients with presumed inoperable lesions. Patients and Methods: Sixty-nine consecutive patients underwent a CT-guided lesion biopsy (n = 67) or abscess/cyst aspiration (n = 2) using the Cosman-Roberts-Wells (CRW) frame. Results: A definitive specific diagnosis was made in 53 of 67 patients (79%). The remaining procedures did not provide a diagnosis because of failure to obtain appropriate specimen (11 patients), findings consistent with non-specific inflammation (2 patients) or uneventful surgical complication requiring termination of the procedure (1 patient). A total of 55 patients (80%) died due to the malignant nature of the lesion, most within six months after the biopsy. The preoperative imaging diagnosis was consistent with the histological diagnosis in 60 patients (87% accuracy). The perioperative morbidity and mortality were nil and. most of the patients were discharged within twenty-four hours. Conclusions: The stereotactic biopsy did not alter either the therapeutic management or the mortality due to the natural course of the lesion. These findings indicate. that the current principle of mandatory histological diagnosis in virtually all non-resectable brain lesions should be re-evaluated taking into account parameters such as: age, medical/neurological status, neuroimaging characteristics, patients’ best interest and health care financial shortages