Electrical-Impedance biofeedback instrument for swallowing rehabilitation

Dysphagia is the difficulty or abnormality of swallowing. It is usually a consequence of another health condition and may be present in any of the phases of swallowing. The cause may be structural or neurological. The effects of dysphagia range in severity; milder symptoms range from discomfort to difficulty swallowing. More severe effects include expelling food or liquid out through the mouth and nose or aspiration of material into the lungs, resulting in heavy bouts of coughing and increasing the risk of developing pneumonia. Treatment for dysphagia, if applicable, therefore depends on the type and cause of dysphagia. Evaluation charts, barium swallow, pharyngeal manometry, and endoscopy are some of the available tools in the diagnosis and classification of dysphagia. Patients diagnosed with neurogenic dysphagia may undergo motor-training exercises for swallowing rehabilitation. However, literature suggests that motor-training exercises are more effective when the patient is presented with some form of interpretable feedback of their motor activity – known as biofeedback. Patients themselves have expressed the view that biofeedback gives something to aim for. To this end various techniques for biofeedback have been formally reviewed, including surface electromyography, acoustic, endoscopy and ultrasound amongst others. Pharyngeal manometry is an invasive procedure which measures pressure along specific sections of an endoscopic-style probe and provides measurements that identify pharyngeal muscle activity sequencing. These measurements have been used as biofeedback information in rehabilitative treatment. However, such techniques are typically performed in a clinical setting and only administered by suitably trained staff. Bio-impedance has been researched and demonstrated in other literature to be a suitable tool for assessing swallowing function, comparisons have been made to manometry with mixed results. Previous Masters students in the University of Canterbury have investigated the suitability of a bio- impedance sensing device to perform as an easy-to-use, non-invasive alternative to intrusive pharyngeal sequence measuring devices. Though impedance measurement changes were obtained from a human subject, the research concluded that the number of measuring channels must be expanded. The device concept was named GULPS (Guided Utility for Latency in Pharyngeal Swallowing). This project aims to expand the number of channels of the GULPS prototype whilst retaining the sensitivity and signal gain of the original. The previous implementations of GULPS took a multi-frequency approach as a means to create channels with 40 kHz and 70 kHz as the selected nominal current injection frequencies. This approach makes adding further channels very challenging as each channel is in effect a complete impedance measurement device, each with their own signal injection circuit, amplifiers, filters and detectors. Each signal injection circuit must have its power supply isolated from the rest posing further design considerations. Channel multiplexing was determined to be the most efficient method by which to add additional channels to the bio-impedance module. This presents its own set of challenges, specifically the amplitude detector board must settle on a steady output considerably faster than the channel multiplexing rate, to allow sufficient time for multiple samples of the channel value to be taken for averaging. A tetrapolar electrode measuring scheme was selected as this approach has proven successful in previous implementations of GULPS, as well as other bio-impedance projects. The number of channels was expanded to sixteen and comparable sensitivity was demonstrated on simulated loads of 120 Ω subjected to a 10% drop in nominal impedance. A test chamber was constructed with channel electrodes spaced vertically along a column filled with saline solution to simulate conditions comparable to that of a human neck. A narrow conductive cylinder attached to an insulating rod was lowered and raised through the path of the current injection and voltage measurement electrodes. This resulted in sufficiently large voltage swings in the corresponding channel with minimal cross- talk or interference to other channels. Though the settling time for the new detector was measured to be sufficiently fast for the desired sampling rate of 1000 Hz per channel, the sampling rate had to be lowered to 700 Hz in the final implementation of the GULPS hardware. The cumulative effect of series-connected resistances meant filtering capacitors had to be lowered to almost parasitic values to try to maintain the required time constants, until the delays could be reduced no further. The per-channel bandwidth is limited to 10 Hz after additional filtering at the output stage. The prototype is initiated and configured via USB by an application developed in Visual Studio. The application allows for frequency selection for the constant current source from 70 kHz to 2 MHz so that the most suitable injection frequency could be determined experimentally. Due to time constraints the prototype was not tested on a test subject nor comparisons made to manometry readings. Testing with a simulated load designed to mimic human tissue demonstrated sufficient signal gain and low inter-channel interference, suggesting the device would be suitable to go to human trials

Pathways to functional outcomes in schizophrenia spectrum disorders: Meta-analysis of social cognitive and neurocognitive predictors

The current meta-analysis explored relationships between functional outcomes in schizophrenia spectrum disorders and different domains of neurocognition and social cognition. Literature searches were conducted in PsycINFO, PubMed, and ProQuest to identify articles reporting correlations between cognition domains and functional outcomes. Of 1361 articles identified, 166 met all inclusion criteria (12,868 participants; 518 correlations). Fifty-three random-effects meta-analyses yielded mean correlation estimates for relationships between neurocognition and social cognition and functional outcomes. Overall, associations between social cognition and neurocognition, and functional outcomes demonstrated significant small-to-medium effect sizes. Social cognition explained more unique variance in functioning than neurocognition (7.3% vs. 4.4%; 9.2% total average variance). Social cognition also mediated the relationship between neurocognition and functional outcomes. A significant proportion of the variance in the relationships between cognition and functional outcomes remained unexplained. These findings suggest that integrated interventions targeting both neurocognition and social cognition may optimally improve functional outcomes. Standardized measurement of cognition and functioning, longitudinal studies, and tests of additional moderators (e.g., first episode samples) in future research were identified as important future directions

Prevailing theories of consciousness are challenged by novel cross-modal associations acquired between subliminal stimuli

While theories of consciousness differ substantially, the ‘conscious access hypothesis’, which aligns consciousness with the global accessibility of information across cortical regions, is present in many of the prevailing frameworks. This account holds that consciousness is necessary to integrate information arising from independent functions such as the specialist processing required by different senses. We directly tested this account by evaluating the potential for associative learning between novel pairs of subliminal stimuli presented in different sensory modalities. First, pairs of subliminal stimuli were presented and then their association assessed by examining the ability of the first stimulus to prime classification of the second. In Experiments 1-4 the stimuli were word-pairs consisting of a male name preceding either a creative or uncreative profession. Participants were subliminally exposed to two name-profession pairs where one name was paired with a creative profession and the other an uncreative profession. A supraliminal task followed requiring the timed classification of one of those two professions. The target profession was preceded by either the name with which it had been subliminally paired (concordant) or the alternate name (discordant). Experiment 1 presented stimuli auditorily, Experiment 2 visually, and Experiment 3 presented names auditorily and professions visually. All three experiments revealed the same inverse priming effect with concordant test pairs associated with significantly slower classification judgements. Experiment 4 sought to establish if learning would be more efficient with supraliminal stimuli and found evidence that a different strategy is adopted when stimuli are consciously perceived. Finally, Experiment 5 replicated the unconscious cross-modal association achieved in Experiment 3 utilising non-linguistic stimuli. The results demonstrate the acquisition of novel cross-modal associations between stimuli which are not consciously perceived and thus challenge the global access hypothesis and those theories embracing it

A Candidate Dual AGN at z=1.175

The X-ray source CXOXBJ142607.6+353351 (CXOJ1426+35), which was identified in a 172 ks Chandra image in the Bootes field, shows double-peaked rest-frame optical/UV emission lines, separated by 0.69" (5.5 kpc) in the spatial dimension and by 690 km s^-1 in the velocity dimension. The high excitation lines and emission line ratios indicate both systems are ionized by an AGN continuum, and the double-peaked profile resembles that of candidate dual AGN. At a redshift of z=1.175, this source is the highest redshift candidate dual AGN yet identified. However, many sources have similar emission line profiles for which other interpretations are favored. We have analyzed the substantial archival data available in this field, as well as acquired near-infrared (NIR) adaptive optics (AO) imaging and NIR slit spectroscopy. The X-ray spectrum is hard, implying a column density of several 10^23 cm^-2. Though heavily obscured, the source is also one of the brightest in the field, with an absorption-corrected 2-10 keV luminosity of ~10^45 erg s^-1. Outflows driven by an accretion disk may produce the double-peaked lines if the central engine accretes near the Eddington limit. However, we may be seeing the narrow line regions of two AGN following a galactic merger. While the AO image reveals only a single source, a second AGN would easily be obscured by the significant extinction inferred from the X-ray data. Understanding the physical processes producing the complex emission line profiles seen in CXOJ1426+35 and related sources is important for interpreting the growing population of dual AGN candidates.Comment: 18 pages and 9 figures. Accepted for publication in The Astrophysical Journa

Towards the Consistent Inclusion of People With Aphasia in Stroke Research Irrespective of Discipline.

People with aphasia have been systematically excluded from stroke research or included without the necessary modifications, threatening external study validity. In this paper, we propose that 1) the inclusion of people with aphasia should be considered as standard in stroke research irrespective of discipline and that 2) modifications should be made to stroke research procedures to support people with aphasia to achieve meaningful and valid inclusion. We argue that outright exclusion of this heterogenous population from stroke research based purely on a diagnosis of aphasia is rarely required and present a rationale for deliberate inclusion of people with aphasia in stroke research. The purpose of this paper is fourfold: 1) to highlight the issue and implications of excluding people with aphasia from stroke research; 2) to acknowledge the current barriers to including people with aphasia in stroke research; 3) to provide stroke researchers with methods to enable inclusion, including recommendations, resources, and guidance; and 4) to consider research needed to develop aphasia inclusive practices in stroke research