Neural Mechanisms of Attentional Control for Objects: Decoding EEG Alpha When Anticipating Faces, Scenes,and Tools.

Attentional selection mechanisms in visual cortex involve changes in oscillatory activity in the EEG alpha band (8-12 Hz), with decreased alpha indicating focal cortical enhancement and increased alpha indicating suppression. This has been observed for spatial selective attention and attention to stimulus features such as color versus motion. We investigated whether attention to objects involves similar alpha-mediated changes in focal cortical excitability. In experiment 1, 20 volunteers (8 males; 12 females) were cued (80% predictive) on a trial-by-trial basis to different objects (faces, scenes, or tools). Support vector machine decoding of alpha power patterns revealed that late (>500 ms latency) in the cue-to-target foreperiod, only EEG alpha differed with the to-be-attended object category. In experiment 2, to eliminate the possibility that decoding of the physical features of cues led to our results, 25 participants (9 males; 16 females) performed a similar task where cues were nonpredictive of the object category. Alpha decoding was now only significant in the early (<200 ms) foreperiod. In experiment 3, to eliminate the possibility that task set differences between the different object categories led to our experiment 1 results, 12 participants (5 males; 7 females) performed a predictive cuing task where the discrimination task for different objects was identical across object categories. The results replicated experiment 1. Together, these findings support the hypothesis that the neural mechanisms of visual selective attention involve focal cortical changes in alpha power not only for simple spatial and feature attention, but also for high-level object attention in humans.SIGNIFICANCE STATEMENT Attention is the cognitive function that enables relevant information to be selected from sensory inputs so it can be processed in the support of goal-directed behavior. Visual attention is widely studied, yet the neural mechanisms underlying the selection of visual information remain unclear. Oscillatory EEG activity in the alpha range (8-12 Hz) of neural populations receptive to target visual stimuli may be part of the mechanism, because alpha is thought to reflect focal neural excitability. Here, we show that alpha-band activity, as measured by scalp EEG from human participants, varies with the specific category of object selected by attention. This finding supports the hypothesis that alpha-band activity is a fundamental component of the neural mechanisms of attention.

Viscous effects in a static physical model of the uniform glottis.

The classic work on laryngeal flow resistance by van den Berg et al. [J. Acoust. Soc. Am. 29, 626-631 (1957)] is revisited. These authors used a formula to summarize their measurements, and thus they separated the effects of entrance loss and pressure recovery from those of viscosity within the glottis. Analysis of intraglottal pressure distributions obtained from the physical model M5 [R. Scherer et al., J. Acoust. Soc. Am. 109, 1616-1630 (2001)] reveals substantial regions within the glottis where the pressure gradient is almost constant for glottal diameters from 0.005 to 0.16 cm, as expected when viscous effects dominate the flow resistance of a narrow channel. For this set of glottal diameters, the part of the pressure gradient that has a linear dependence on the glottal volume velocity is isolated. The inverse cube diameter of the Poiseuille expression for glottal flows is examined with the data set provided by the M5 intraglottal pressure distributions. The Poiseuille effect is found to give a reasonable account of viscous effects in the diameter interval from 0.0075 to 0.02 cm, but an inverse 2.59 power law gives a closer fit across all diameters.

Patient factors associated with failure to diagnose tuberculosis in the emergency department.

BACKGROUND: Emergency department (ED) presentation of pulmonary tuberculosis (TB) can be highly atypical and an ED visit might be the only health care interaction for high-risk patients. OBJECTIVE: Our objective was to identify patient factors associated with discharge without a diagnosis of TB during an infectious ED visit. METHODS: The study population consisted of 150 patients from 2000 to 2009 with 190 infectious ED visits. Patients were initially identified from the state registry of confirmed TB cases and epidemiological characteristics were identified prospectively during case investigation. A retrospective review was performed for clinical characteristics of visits dichotomized according to whether the diagnosis of TB was made during the ED visit. RESULTS: Analysis revealed that 77% of all infectious-patient visits ended with a diagnosis of TB. A TB diagnosis was more likely when patients presented with pulmonary or infectious chief complaints, endorsed cough, subjective fever, chills, dyspnea, previous TB infection, or had an abnormal lung examination or chest x-ray study. Patients were significantly less likely to be diagnosed with TB when they were unresponsive during clinical evaluation or when they reported a history of both homelessness and any substance abuse during the last year. In addition, these characteristics were independent predictors of nondiagnosis when traditional TB risk factors or abnormal vital signs were considered. CONCLUSIONS: Patients with atypical presentations, as well as those who were unresponsive or reported a history of homelessness and substance abuse, were at greater risk for nondiagnosis of TB during an infectious ED visit.

Pressure distributions in a static physical model of the uniform glottis: entrance and exit coefficients.

Pressure distributions for the uniform glottis were obtained with a static physical model (M5). Glottal diameters of d=0.005, 0.0075, 0.01, 0.02, 0.04, 0.08, 0.16, and 0.32 cm were used with a range of phonatory transglottal pressures. At each pressure and diameter, entrance loss and exit coefficients were determined. In general, both coefficients decreased in value as the transglottal pressure or the diameter increased. Entrance loss coefficients ranged from 0.69 to 17.6. Use of these coefficients with the measured flow rates in straightforward equations accurately reproduced the pressure distributions within the glottis and along the inferior vocal fold surface.