Are dyslexics' visual deficits limited to measures of dorsal stream function?

We tested the hypothesis that the differences in performance between developmental dyslexics and controls on visual tasks are specific for the detection of dynamic stimuli. We found that dyslexics were less sensitive than controls to coherent motion in dynamic random dot displays. However, their sensitivity to control measures of static visual form coherence was not significantly different from that of controls. This dissociation of dyslexics' performance on measures that are suggested to tap the sensitivity of different extrastriate visual areas provides evidence for an impairment specific to the detection of dynamic properties of global stimuli, perhaps resulting from selective deficits in dorsal stream functions. © 2001 Lippincott Williams & Wilkins.

How the brain blinks:towards a neurocognitive model of the attentional blink

When people monitor a visual stream of rapidly presented stimuli for two targets (T1 and T2), they often miss T2 if it falls into a time window of about half a second after T1 onset—the attentional blink (AB). We provide an overview of recent neuroscientific studies devoted to analyze the neural processes underlying the AB and their temporal dynamics. The available evidence points to an attentional network involving temporal, right-parietal and frontal cortex, and suggests that the components of this neural network interact by means of synchronization and stimulus-induced desynchronization in the beta frequency range. We set up a neurocognitive scenario describing how the AB might emerge and why it depends on the presence of masks and the other event(s) the targets are embedded in. The scenario supports the idea that the AB arises from ‘‘biased competition’’, with the top–down bias being generated by parietal–frontal interactions and the competition taking place between stimulus codes in temporal cortex.

To which extent can attention and/or modulation explains deficits in dyslexia?

This thesis investigates the visual deficits associated with developmental dyslexia, particularly that of visual attention. Visual attention has previously been investigated in a wide array of behavioural and psychophysical (amongst others) studies but not many have produced consistent findings. Attention processes are believed to play an integral part in depicting the overall "extent" of reading deficits in dyslexia, so it was of paramount importance to aim at such attention mechanisms in this research. The experiments in this thesis focused on signal enhancement and noise (distractor) exclusion. Given the flexibility of the visual search paradigms employed in this research, factors such as visual crowding and attention distribution was also investigated. The experiments systematically manipulated noise (by increasing distractor count, i.e. set-size), crowding (varying the spacing between distractors), attention allocation (use of peripheral cues to direct attention), and attention distribution (influence of one visual field over the other), all of which were tied to a critical factor, the "location/spatial/decisional uncertainty". Adults with dyslexia were: (i) able to modulate attention appropriately using peripheral pre-cues, (ii) severely affected by crowding, and (iii) unable to counteract increased set-sizes when post or un-cued, the latter signifying poor distractor (noise) suppression. By controlling for location uncertainty, the findings confirmed that adults with dyslexia were yet again affected by crowding and set-size, in addition to an asymmetric attention distribution. Confounding effects of ADHD symptoms did not explain a significant independent variance in performance, suggesting that the difficulty shown by adult dyslexics were not accounted for by co-morbid ADHD. Furthermore, the effects of crowding, set-size and asymmetric attention correlated significantly with literacy, but not ADHD measures. It is believed that a more diffuse and an asymmetric attention system (in dyslexia) to be the limiting factor concerning noise exclusion and attention distribution. The findings from this thesis add to the current understanding of the potential role of deficits in visual attention in dyslexia and in the literacy difficulties experienced by this population.

Pressure ulcers and nutritional deficits in elderly long-term care patients: Effects of a comprehensive nutritional program on pressure ulcer healing, length of hospital stay and charges to patients

The elderly are at the highest risk of developing pressure ulcers that result in prolonged hospitalization, high health care costs, increased mortality, and decreased quality of life. The burden of pressure ulcers will intensify because of a rapidly increasing elderly population in the United States (US). Poor nutrition is a major predictor of pressure ulcer formation. The purpose of this study was to examine the effects of a comprehensive, interdisciplinary nutritional protocol on: (1) pressure ulcer wound healing (2) length of hospital stays, and (3) charges for pressure ulcer management. Using a pre-intervention/post intervention quasi-experimental design the study sample was composed of 100 patients 60 years or older, admitted with or acquiring a pressure ulcer. A pre-intervention group (n= 50) received routine pressure ulcer care (standard diet, dressing changes, and equipment). A post-intervention group received routine care plus an interdisciplinary nutrition intervention (physical therapy, speech therapy, occupational therapy, added protein and calories to the diet). Research questions were analyzed using descriptive statistics, frequencies, Chi-Square Tests, and T-tests. Findings indicated that the comprehensive, interdisciplinary nutritional protocol had a significant effect on the rate of wound healing in Week3 and Week4, total hospital length of stay (pre-intervention M= 43.2 days, SD=31.70 versus M=31.77, SID-12.02 post-intervention), and pressure ulcer length of stay (pre-intervention 25.28 days, SD5.60 versus 18.40 days, SD 5.27 post-intervention). Although there was no significant difference in total charges for the pre-intervention group ($727,245.00) compared to the post-intervention group ($702,065.00), charges for speech (m=$5885.12, SD=$332.55), pre albumin (m=$808.52,SD= $332.55), and albumin($278 .88, SD=55.00) were higher in the pre-intervention group and charges for PT ($5721.26, SD$3655.24) and OT($2544 .64, SD=1712.863) were higher in the post-intervention group. Study findings indicate that this comprehensive nutritional intervention was effective in improving pressure ulcer wound healing, decreasing both hospital length of stay for treatment of pressure ulcer and total hospital length of stay while showing no significant additional charges for treatment of pressure ulcers.

Hidden Communication Deficits in Children with Autism and Early Behavioral Interventions

Taking a behavioral systems approach to autism, early hidden communicative deficits are introduced as precursors of autistic development. This paper argues that early identification of communication (language and cognition) impairments followed by intensive behavioral interventions, as early as infancy, may have the most preventive effect on the development of autism.

Human Synaptic Plasticity Gene Expression Profile and Dendritic Spine Density Changes in HIV-Infected Human CNS Cells: Role in HIV-Associated Neurocognitive Disorders (HAND)

HIV-associated neurocognitive disorders (HAND) is characterized by development of cognitive, behavioral and motor abnormalities, and occur in approximately 50% of HIV infected individuals. Our current understanding of HAND emanates mainly from HIV-1 subtype B (clade B), which is prevalent in USA and Western countries. However very little information is available on neuropathogenesis of HIV-1 subtype C (clade C) that exists in Sub-Saharan Africa and Asia. Therefore, studies to identify specific neuropathogenic mechanisms associated with HAND are worth pursuing to dissect the mechanisms underlying this modulation and to prevent HAND particularly in clade B infection. In this study, we have investigated 84 key human synaptic plasticity genes differential expression profile in clade B and clade C infected primary human astrocytes by using RT2 Profile PCR Array human Synaptic Plasticity kit. Among these, 31 and 21 synaptic genes were significantly (≥3 fold) down-regulated and 5 genes were significantly (≥3 fold) up-regulated in clade B and clade C infected cells, respectively compared to the uninfected control astrocytes. In flow-cytometry analysis, down-regulation of postsynaptic density and dendrite spine morphology regulatory proteins (ARC, NMDAR1 and GRM1) was confirmed in both clade B and C infected primary human astrocytes and SK-N-MC neuroblastoma cells. Further, spine density and dendrite morphology changes by confocal microscopic analysis indicates significantly decreased spine density, loss of spines and decreased dendrite diameter, total dendrite and spine area in clade B infected SK-N-MC neuroblastoma cells compared to uninfected and clade C infected cells. We have also observed that, in clade B infected astrocytes, induction of apoptosis was significantly higher than in the clade C infected astrocytes. In conclusion, this study suggests that down-regulation of synaptic plasticity genes, decreased dendritic spine density and induction of apoptosis in astrocytes may contribute to the severe neuropathogenesis in clade B infection.

Interactive Effects of Morphine on HIV Infection: Role in HIV-Associated Neurocognitive Disorder

HIV epidemic continues to be a severe public health problem and concern within USA and across the globe with about 33 million people infected with HIV. The frequency of drug abuse among HIV infected patients is rapidly increasing and is another major issue since injection drug users are at a greater risk of developing HIV associated neurocognitive dysfunctions compared to non-drug users infected with HIV. Brain is a major target for many of the recreational drugs and HIV. Evidences suggest that opiate drug abuse is a risk factor in HIV infection, neural dysfunction and progression to AIDS. The information available on the role of morphine as a cofactor in the neuropathogenesis of HIV is scanty. This review summarizes the results that help in understanding the role of morphine use in HIV infection and neural dysfunction. Studies show that morphine enhances HIV-1 infection by suppressing IL-8, downregulating chemokines with reciprocal upregulation of HIV coreceptors. Morphine also activates MAPK signaling and downregulates cAMP response element-binding protein (CREB). Better understanding on the role of morphine in HIV infection and mechanisms through which morphine mediates its effects may help in devising novel therapeutic strategies against HIV-1 infection in opiate using HIV-infected population.

The influence of neurocognitive impairment, alcohol and other drug (AOD) use, and psychosocial factors on antiretroviral treatment adherence, service utilization and viral load among HIV-seropositive adults

Among people living with HIV (PLWH), adherence to antiretroviral therapy (ART) can be affected by problems of neurocognitive (NC) impairment, stress, alcohol and other drug (AOD) abuse, and other barriers. The aims of this research were to: (1) examine factors associated with NC impairment, (2) explore relationships between psychosocial variables with ART adherence and viral load (VL), and (3) evaluate the efficacy of an evidence-based intervention in improving ART adherence, increasing service utilization, and decreasing VL. The first study (n=370) was cross sectional and used structural equation modeling to test whether AOD use, years living with HIV, and time from HIV diagnosis to seeking care were associated with poorer NC functioning. The second study (n=246) used similar methods to test the hypothesis that stress, barriers to adherence, NC impairment, poor social support, and AOD use were related to lower VL mediated by ART adherence. The third study (n=243) evaluated an evidence-based, eight-session program to improve ART adherence, reduce VL, and increase service utilization in a randomized controlled trial. Study participants were PLWH living in South Florida, 18 to 60 years old, with a history of alcohol abuse enrolled from January 2009 through November 2012. Secondary analysis of available data showed: (1) scores on interference with executive functioning increased by 0.32 for each day of marijuana use and 1.18 for each year living with HIV, but no association was found between alcohol use and NC functioning; (2) each barrier to adherence was associated with a 10% decrease in adherence to ART and a 0.42 unit increase in VL (log10) and the relationship between barriers and VL was partially mediated by ART adherence; (3) participants in the evidence-based program were more likely than the comparison group to report an undetectable VL (OR=2.25, p<0.01) at 6 months, but not 3 months, post-intervention. Psychosocial factors affect VL, but ART adherence is essential in achieving an undetectable VL in PLWH.

Peer Support: An Intervention To Facilitate Second Language Acquisition In Students With Asperger Syndrome And Primary Language Deficits

This is a study of a peer support program to aid students in secondary school struggling to learn a second language (for college entrance requirements) who have Asperger Syndrone and primary language deficits.

Pressure ulcers and nutritional deficits in elderly long-term care patients : effects of a comprehensive nutritional program on pressure ulcer healing, length of hospital stay and charges to patients

The elderly are at the highest risk of developing pressure ulcers that result in prolonged hospitalization, high health care costs, increased mortality, and decreased quality of life. The burden of pressure ulcers will intensify because of a rapidly increasing elderly population in the United States (US). Poor nutrition is a major predictor of pressure ulcer formation. The purpose of this study was to examine the effects of a comprehensive, interdisciplinary nutritional protocol on: 1) pressure ulcer wound healing 2) length of hospital stays, and 3) charges for pressure ulcer management. Using a pre-intervention/post intervention quasi-experimental design the study sample was composed of 100 patients 60 years or older, admitted with or acquiring a pressure ulcer. A pre-intervention group (n= 50) received routine pressure ulcer care (standard diet, dressing changes, and equipment). A post-intervention group received routine care plus an interdisciplinary nutrition intervention (physical therapy, speech therapy, occupational therapy, added protein and calories to the diet). Research questions were analyzed using descriptive statistics, frequencies, Chi-Square Tests, and T-tests. Findings indicated that the comprehensive, interdisciplinary nutritional protocol had a significant effect on the rate of wound healing in Week3 and Week4, total hospital length of stay (pre-intervention M= 43.2 days, SD=31.70 versus M=31.77, SD=12.02 post-intervention), and pressure ulcer length of stay (pre-intervention 25.28 days, SD5.60 versus 18.40 days, SD 5.27 post-intervention). Although there was no significant difference in total charges for the pre-intervention group ($727,245.00) compared to the post-intervention group ($702,065.00), charges for speech (m=$5885.12, SD=$332.55), pre albumin (m=$808.52,SD= $332.55), and albumin($278 .88, SD=55.00) were higher in the pre-intervention group and charges for PT ($5721.26, SD$3655.24) and OT($2544 .64, SD=1712.863) were higher in the post-intervention group. Study findings indicate that this comprehensive nutritional intervention was effective in improving pressure ulcer wound healing, decreasing both hospital length of stay for treatment of pressure ulcer and total hospital length of stay while showing no significant additional charges for treatment of pressure ulcers.

The role of supraspinal excitability in the development of healthy-limb deficits following anterior cruciate ligament injury

In the current study, we examined how supraspinal and spinal excitability were altered bilaterally after unilateral anterior cruciate ligament reconstruction (ACLr). 7 participants with ACLr and 7 healthy controls underwent transcranial magnetic stimulation (TMS) and electrical stimulation. To evaluate supraspinal excitability, resting motor thresholds (RMT) and motor evoked potential (MEP) stimulus response curves (SRC) were used. To measure spinal excitability, H-reflex SRC gain was assessed. Mixed factorial ANOVAs were used to compare measures between limbs and between groups. Cohen’s d was used to assess effect sizes between groups. Data indicated no significant differences between subject groups or between limbs. However, large effect sizes were found between limbs for H-reflex gain and RMTs suggesting that ACLr can have an effect on some of the variables examined. This study identified decreases in strength in the injured limbs and that subjects with an ACL injury exhibited decreases in spinal and supraspinal excitability of the quadriceps compared to Healthy controls.

Addressing deficits and injustices : the potential epistemic contributions of patients to research

Acknowledgments The research for this paper was primarily funded by an Australian Research Council (ARC) grant (DP120101092), How do we know what works? Ethics and evidence in surgical research. Katrina Hutchison’s research was also partly funded by the ARC Centre of Excellence for Electromaterials Science, where she has worked since June 2015. Discussions about the paper were facilitated by Macquarie University funding of a visit by Vikki A. Entwistle to participate in a Centre for Agency, Values and Ethics (CAVE) seminar on Capabilities Approaches to Justice. The authors would like to thank the anonymous reviewers for a number of helpful comments.

The Impact of Marijuana Use on Memory in Patients with HIV/AIDS

The most robust neurocognitive effect of marijuana use is memory impairment. Memory deficits are also high among persons living with HIV/AIDS, and marijuana use among this population is disproportionately common. Yet research examining neurocognitive outcomes resulting from co-occurring marijuana and HIV is virtually non-existent. The primary aim of this case-controlled study was to identify patterns of neurocognitive impairment among HIV patients who used marijuana compared to HIV patients who did not use drugs by comparing the groups on domain T-scores. Participants included 32 current marijuana users and 37 non-drug users. A comprehensive battery assessed substance use and neurocognitive functioning. Among the full sample, marijuana users performed significantly worse on verbal memory tasks compared to non-drug users and significantly better on attention/working memory tasks. A secondary aim of this study was to test whether the effect of marijuana use on memory was moderated by HIV disease progression, but these models were not significant. This study also examined whether the effect of marijuana use was differentially affected by marijuana use characteristics, finding that earlier age of initiation was associated with worse memory performance. These findings have important clinical implications, particularly given increased legalization of this drug to manage HIV infection.

The Influence of Gene Environment Interaction on the Risk of Cognitive Impairment: Reducing Sexual Risk Behaviors and Alcohol Use in HIV-infected Adults

Memory deficits and executive dysfunction are highly prevalent among HIV-infected adults. These conditions can affect their quality of life, antiretroviral adherence, and HIV risk behaviors. Several factors have been suggested including the role of genetics in relation to HIV disease progression. This dissertation aimed to determine whether genetic differences in HIV-infected individuals were correlated with impaired memory, cognitive flexibility and executive function and whether cognitive decline moderated alcohol use and sexual transmission risk behaviors among HIV-infected alcohol abusers participating in an NIH-funded clinical trial comparing the efficacy of the adapted Holistic Health Recovery Program (HHRP-A) intervention to a Health Promotion Control (HPC) condition in reducing risk behaviors. A total of 267 individuals were genotyped for polymorphisms in the dopamine and serotonin gene systems. Results yielded significant associations for TPH2, GALM, DRD2 and DRD4 genetic variants with impaired executive function, cognitive flexibility and memory. SNPs TPH2 rs4570625 and DRD2 rs6277 showed a risk association with executive function (odds ratio = 2.5, p = .02; 3.6, p = .001). GALM rs6741892 was associated with impaired memory (odds ratio = 1.9, p = .006). At the six-month follow-up, HHRP-A participants were less likely to report trading sex for food, drugs and money (20.0%) and unprotected insertive or receptive oral (11.6%) or vaginal and/or anal sex (3.2%) than HPC participants (49.4%, p