Electric field encephalography for brain activity monitoring.

OBJECTIVE: We describe an early-stage prototype of a new wireless electrophysiological sensor system, called NeuroDot, which can measure neuroelectric potentials and fields at the scalp in a new modality called Electric Field Encephalography (EFEG). We aim to establish the physical validity of the EFEG modality, and examine some of its properties and relative merits compared to EEG. APPROACH: We designed a wireless neuroelectric measurement device based on the Texas Instrument ADS1299 Analog Front End platform and a sensor montage, using custom electrodes, to simultaneously measure EFEG and spatially averaged EEG over a localized patch of the scalp (2 cm × 2 cm). The signal properties of each modality were compared across tests of noise floor, Berger effect, steady-state visually evoked potential (ssVEP), signal-to-noise ratio (SNR), and others. In order to compare EFEG to EEG modalities in the frequency domain, we use a novel technique to compute spectral power densities and derive narrow-band SNR estimates for ssVEP signals. A simple binary choice brain-computer-interface (BCI) concept based on ssVEP is evaluated. Also, we present examples of high quality recording of transient Visually Evoked Potentials and Fields (tVEPF) that could be used for neurological studies. MAIN RESULTS: We demonstrate the capability of the NeuroDot system to record high quality EEG signals comparable to some recent clinical and research grade systems on the market. We show that the locally-referenced EFEG metric is resistant to certain types of movement artifacts. In some ssVEP based measurements, the EFEG modality shows promising results, demonstrating superior signal to noise ratios than the same recording processed as an analogous EEG signal. We show that by using EFEG based ssVEP SNR estimates to perform a binary classification in a model BCI, the optimal information transfer rate (ITR) can be raised from 15 to 30 bits per minute-though these preliminary results are likely sensitive to inter-subject variations and choice of scalp locations, so require further investigation. SIGNIFICANCE: Enhancement of ssVEP SNR using EFEG has the potential to improve visually based BCIs and diagnostic paradigms. The time domain analysis of tVEPF signals shows robust features in the electric field components that might have clinical relevance beyond classical VEP approaches.

Mandrake toxicity. A case of mistaken identity.

A 31-year-old man ingested an unknown amount of mandrake plant purchased at a local health food store and came to the emergency department with severe nausea and vomiting. He was hospitalized overnight but recovered uneventfully without obvious adverse systemic effects. This plant was almost certainly Podophyllum peltatum based on chromatographic identification of podophyllotoxin in a sample. However, the patient had mistakenly believed he was taking the anticholinergic and hallucinatory plant Mandragora officinarum, which is also known as mandrake. Other users of herbal substances and authors of the medical literature have also confused these 2 versions of mandrake. Given the growing popularity of alternative therapies, physicians should understand the distinction between these substances and should be aware of the medical effects of other commonly used herbal remedies.

Social change and HIV in the former USSR: the making of a new epidemic.

This paper describes the development of the recent HIV epidemic in countries of the former Soviet Union. It explores the socio-political and economic roots of an injection-drug-driven HIV epidemic associated with a drug culture that facilitates HIV transmission. This review, based on many unpublished reports, studies and field notes, discusses the new social and health context in which the epidemic is developing. The evidence of a growing number of drug users in the region is discussed and drug injection behaviour described. The authors present selected data on the heterosexual transmission of HIV and linkages between the drug-linked HIV epidemic and its further spread into the non-injecting population. The potential overlap with the still uncontrolled syphilis epidemic that began in 1990 is probably a key factor in the future of HIV spread in the region. Until now, HIV infection among STD patients has been extremely low. However, rapid changes in sexual norms and behaviours, the growing commercial sex industry, and increased mobility soon may affect the current situation. The huge economic and socio-political crises currently affecting the region have created a "risk situation" for the spread of HIV. Concerns are raised about the appropriateness and the scope of government and non-governmental approaches to the exploding HIV and STD epidemics.

Country watch: Chile.

PIP: Confidentiality is a critical issue in the conduct of HIV tests in Chile. Though HIV testing is confidential in the public health system (through the use of a coding system), syphilis tests which are conducted simultaneously with HIV, require clients to provide their identity as well as address. In response to this concern, the National AIDS Commission has launched training programs in all 26 public health services for staff involved with HIV/AIDS programs. The training programs allow professional staff and volunteers to understand the importance of confidentiality. Nevertheless, cases of breaches of confidentiality have been reported, raising doubts as to the ability of the system to maintain confidentiality. These cases often occur at the hospitals or clinics where staff is insensitive to the needs of their clients and oblivious of their rights. Hence, it is highlighted that to reinforce confidentiality, patients, advocacy groups, human rights activists and health care administrators must pay attention to the many ways in which confidentiality is breached.^ieng