Proactive Interference Does Not Meaningfully Distort Visual Working Memory Capacity Estimates in the Canonical Change Detection Task

The change detection task has become a standard method for estimating the storage capacity of visual working memory. Most researchers assume that this task isolates the properties of an active short-term storage system that can be dissociated from long-term memory systems. However, long-term memory storage may influence performance on this task. In particular, memory traces from previous trials may create proactive interference that sometimes leads to errors, thereby reducing estimated capacity. Consequently, the capacity of visual working memory may be higher than is usually thought, and correlations between capacity and other measures of cognition may reflect individual differences in proactive interference rather than individual differences in the capacity of the short-term storage system. Indeed, previous research has shown that change detection performance can be influenced by proactive interference under some conditions. The purpose of the present study was to determine whether the canonical version of the change detection task – in which the to-be-remembered information consists of simple, briefly presented features – is influenced by proactive interference. Two experiments were conducted using methods that ordinarily produce substantial evidence of proactive interference, but no proactive interference was observed. Thus, the canonical version of the change detection task can be used to assess visual working memory capacity with no meaningful influence of proactive interference

Activation of the phosphosignaling protein CheY. I. Analysis of the phosphorylated conformation by 19F NMR and protein engineering

CheY, the 14-kDa response regulator protein of the Escherichia coli chemotaxis pathway, is activated by phosphorylation of Asp57. In order to probe the structural changes associated with activation, an approach which combines 19F NMR, protein engineering, and the known crystal structure of one conformer has been utilized. This first of two papers examines the effects of Mg(II) binding and phosphorylation on the conformation of CheY. The molecule was selectively labeled at its six phenylalanine positions by incorporation of 4-fluorophenylalanine, which yielded no significant effect on activity. One of these 19F probe positions monitored the vicinity of Lys109, which forms a salt bridge to Asp57 in the apoprotein and has been proposed to act as a structural "switch" in activation. 19F NMR chemical shift studies of the labeled protein revealed that the binding of the cofactor Mg(II) triggered local structural changes in the activation site, but did not perturb the probe of the Lys109 region. The structural changes associated with phosphorylation were then examined, utilizing acetyl phosphate to chemically generate phsopho-CheY during NMR acquisition. Phosphorylation triggered a long-range conformational change extending from the activation site to a cluster of 4 phenylalanine residues at the other end of the molecule. However, phosphorylation did not perturb the probe of Lys109. The observed phosphorylated conformer is proposed to be the first step in the activation of CheY; later steps appear to perturb Lys109, as evidenced in the following paper. Together these results may give insight into the activation of other prokaryotic response regulators

“Top-down” Does Not Mean “Voluntary”

Attention researchers have long debated the roles of top-down and bottom-up mechanisms in controlling attention. Theeuwes (2018) has argued that that top-down control is much less common than typically assumed and that a third mechanism—selection history—plays an underappreciated role in guiding visual attention. Although Theeuwes has made a strong case for the importance of selection history, his arguments for a limited role of top-down mechanisms involve conflating the terms “top-down” and “voluntary.” Cognitive psychologists typically use the term “top-down” processing to refer to any perceptual phenomenon that is influenced by context, learning, or expectation, which would include selection history. This highlights a broad problem in attention capture research: The terms used to describe attentional control are often poorly defined, and much current debate seems to be related to the meaning of words. To move forward in understanding the actual mechanisms of attentional control, we must agree on what terms such as “top-down” and “bottom-up” actually mean

Both unmedicated and medicated individuals with schizophrenia show impairments across a wide array of cognitive and reinforcement learning tasks

BACKGROUND: Schizophrenia is a disorder characterized by pervasive deficits in cognitive functioning. However, few well-powered studies have examined the degree to which cognitive performance is impaired even among individuals with schizophrenia not currently on antipsychotic medications using a wide range of cognitive and reinforcement learning measures derived from cognitive neuroscience. Such research is particularly needed in the domain of reinforcement learning, given the central role of dopamine in reinforcement learning, and the potential impact of antipsychotic medications on dopamine function. METHODS: The present study sought to fill this gap by examining healthy controls (N = 75), unmedicated (N = 48) and medicated (N = 148) individuals with schizophrenia. Participants were recruited across five sites as part of the CNTRaCS Consortium to complete tasks assessing processing speed, cognitive control, working memory, verbal learning, relational encoding and retrieval, visual integration and reinforcement learning. RESULTS: Individuals with schizophrenia who were not taking antipsychotic medications, as well as those taking antipsychotic medications, showed pervasive deficits across cognitive domains including reinforcement learning, processing speed, cognitive control, working memory, verbal learning and relational encoding and retrieval. Further, we found that chlorpromazine equivalency rates were significantly related to processing speed and working memory, while there were no significant relationships between anticholinergic load and performance on other tasks. CONCLUSIONS: These findings add to a body of literature suggesting that cognitive deficits are an enduring aspect of schizophrenia, present in those off antipsychotic medications as well as those taking antipsychotic medications

Electrophysiological measurement of the effect of inter-stimulus competition on early cortical stages of human vision

AbstractCompetition between inputs in early visual cortex has been established as a key determinant in perception through decades of animal single cell and human fMRI research. We developed a novel ERP paradigm allowing this competition to be studied in humans, affording an opportunity to gain further insight into how competition is reflected at the neural level. Checkerboard stimuli were presented to elicit C1 (indexing processing in V1), C2 (hypothesized to reflect V1 after extrastriate feedback), and P1 (extrastriate) components. Stimuli were presented in three randomized conditions: single stimulus, near proximity pairs and far proximity pairs. Importantly, near stimuli (0.16° visual angle apart) were positioned to compete in primary visual cortex, whereas far stimuli (2° apart) were positioned to compete in extrastriate visual areas.As predicted, the degree and spatial range of competition increased from the C1 component to the C2 and P1 components. Specifically, competitive interactions in C1 amplitude were modest and present only for near-proximity pairs, whereas substantial competition was present for the P1, even for far-proximity pairs. To our knowledge, this is the first study to measure how competition unfolds over time in human visual cortex. Importantly, this method provides an empirical means of measuring competitive interactions at specific stages of visual processing, rendering it possible to rigorously test predictions about the effects of competition on perception, attention, and working memory

Quality and correlates of medical record documentation in the ambulatory care setting

BACKGROUND: Documentation in the medical record facilitates the diagnosis and treatment of patients. Few studies have assessed the quality of outpatient medical record documentation, and to the authors' knowledge, none has conclusively determined the correlates of chart documentation. We therefore undertook the present study to measure the rates of documentation of quality of care measures in an outpatient primary care practice setting that utilizes an electronic medical record. METHODS: We reviewed electronic medical records from 834 patients receiving care from 167 physicians (117 internists and 50 pediatricians) at 14 sites of a multi-specialty medical group in Massachusetts. We abstracted information for five measures of medical record documentation quality: smoking history, medications, drug allergies, compliance with screening guidelines, and immunizations. From other sources we determined physicians' specialty, gender, year of medical school graduation, and self-reported time spent teaching and in patient care. RESULTS: Among internists, unadjusted rates of documentation were 96.2% for immunizations, 91.6% for medications, 88% for compliance with screening guidelines, 61.6% for drug allergies, 37.8% for smoking history. Among pediatricians, rates were 100% for immunizations, 84.8% for medications, 90.8% for compliance with screening guidelines, 50.4% for drug allergies, and 20.4% for smoking history. While certain physician and patient characteristics correlated with some measures of documentation quality, documentation varied depending on the measure. For example, female internists were more likely than male internists to document smoking history (odds ratio [OR], 1.90; 95% confidence interval [CI], 1.27 – 2.83) but were less likely to document drug allergies (OR, 0.51; 95% CI, 0.35 – 0.75). CONCLUSIONS: Medical record documentation varied depending on the measure, with room for improvement in most domains. A variety of characteristics correlated with medical record documentation, but no pattern emerged. Further study could lead to targeted interventions to improve documentation

High-speed, sub-pull-in voltage MEMS switching.

We have proposed and demonstrated MEMS switching devices that take advantage of the dynamic behavior of the MEMS devices to provide lower voltage actuation and higher switching speeds. We have explored the theory behind these switching techniques and have demonstrated these techniques in a range of devices including MEMS micromirror devices and in-plane parallel plate MEMS switches. In both devices we have demonstrated switching speeds under one microsecond which has essentially been a firm limit in MEMS switching. We also developed low-loss silicon waveguide technology and the ability to incorporate high-permittivity dielectric materials with MEMS. The successful development of these technologies have generated a number of new projects and have increased both the MEMS switching and optics capabilities of Sandia National Laboratories

Sins of Omission

Little is known about the relative incidence of serious errors of omission versus errors of commission. Objective : To identify the most common substantive medical errors identified by medical record review. Design : Retrospective cohort study. Setting : Twelve Veterans Affairs health care systems in 2 regions. Participants : Stratified random sample of 621 patients receiving care over a 2-year period. Main Outcome Measure : Classification of reported quality problems. Methods : Trained physicians reviewed the full inpatient and outpatient record and described quality problems, which were then classified as errors of omission versus commission. Results : Eighty-two percent of patients had at least 1 error reported over a 13-month period. The average number of errors reported per case was 4.7 (95% confidence intervals [CI]: 4.4, 5.0). Overall, 95.7% (95% CI: 94.9%, 96.4%) of errors were identified as being problems with underuse. Inadequate care for people with chronic illnesses was particularly common. Among errors of omission, obtaining insufficient information from histories and physicals (25.3%), inadequacies in diagnostic testing (33.9%), and patients not receiving needed medications (20.7%) were all common. Out of the 2,917 errors identified, only 27 were rated as being highly serious, and 26 (96%) of these were errors of omission. Conclusions : While preventing iatrogenic injury resulting from medical errors is a critically important part of quality improvement, we found that the overwhelming majority of substantive medical errors identifiable from the medical record were related to people getting too little medical care, especially for those with chronic medical conditions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74567/1/j.1525-1497.2005.0152.x.pd

The gender specific frequency of risk factor and CHD diagnoses prior to incident MI: A community study

BACKGROUND: CHD is a chronic disease often present years prior to incident AMI. Earlier recognition of CHD may be associated with higher levels of recognition and treatment of CHD risk factors that may delay incident AMI. To assess timing of CHD and CHD risk factor diagnoses prior to incident AMI. METHODS: This is a 10-year population based medical record review study that included all medical care providers in Olmsted County, Minnesota for all women and a sample of men residing in Olmsted County, MN with confirmed incident AMI between 1995 and 2000. RESULTS: All medical care for the 10 years prior to incident AMI was reviewed for 150 women and 148 men (38% sample) in Olmsted County, MN. On average, women were older than men at the time of incident AMI (74.7 versus 65.9 years, p < 0.0001). 30.4% of the men and 52.0% of the women received diagnoses of CHD prior to incident AMI (p = 0.0002). Unrecognized and untreated CHD risk factors were present in both men (45% of men 5 years prior to AMI) and women (22% of women 5 years prior to first AMI), more common in men and those without a diagnosis of CHD prior to incident AMI (p < 0.0001). CONCLUSION: A CHD diagnosis prior to incident AMI is associated with higher rates of recognition and treatment of CHD risk factors suggesting that diagnosing CHD prior to AMI enhances opportunities to lower the risk of future CHD events