Boundary completion is automatic and dissociable from shape discrimination

Normal visual perception readily overcomes suboptimal or degraded viewing conditions through perceptual filling-in processes, enhancing object recognition and discrimination abilities. This study used visual evoked potential (VEP) recordings in conjunction with electrical neuroimaging analyses to determine the spatiotemporal brain dynamics of boundary completion and shape discrimination processes in healthy humans performing the so-called "thin/fat" discrimination task (Ringach and Shapley, 1996) with stimuli producing illusory contours. First, results suggest that boundary completion processes occur independent of subjects' accuracy on the discrimination task. Modulation of the VEP to the presence versus absence of illusory contours [the IC effect (Murray et al., 2002)] was indistinguishable in terms of response magnitude and scalp topography over the 124-186 ms poststimulus period, regardless of whether task performance was correct. This suggests that failure on this discrimination task is not primarily a consequence of failed boundary completion. Second, the electrophysiological correlates of thin/fat shape discrimination processes are temporally dissociable from those of boundary completion, occurring during a substantially later phase of processing (approximately 330-406 ms). The earlier IC effect was unaffected by whether the perceived contour produced a thin or fat shape. In contrast, later time periods of the VEP modulated according to perceived shape only in the case of stimuli producing illusory contours, but not for control stimuli for which performance was at near-chance levels. Collectively, these data provide further support for a multistage model of object processing under degraded viewing conditions

Contributions of early cortical processing and reading ability to functional status in individuals at clinical high risk for psychosis

Background: There is a growing recognition that individuals at clinical high risk need intervention for functional impairments, along with emerging psychosis, as the majority of clinical high risk (CHR) individuals show persistent deficits in social and role functioning regardless of transition to psychosis. Recent studies have demonstrated reduced reading ability as a potential cause of functional disability in schizophrenia, related to underlying deficits in generation of mismatch negativity (MMN). The present study extends these findings to subjects at CHR. Methods: The sample consisted of 34 CHR individuals and 33 healthy comparison subjects (CNTLs) from the Recognition and Prevention (RAP) Program at the Zucker Hillside Hospital in New York. At baseline, reading measures were collected, along with MMN to pitch, duration, and intensity deviants, and measures of neurocognition, and social and role (academic/work) functioning. Results: CHR subjects showed impairments in reading ability, neurocognition, and MMN generation, relative to CNTLs. Lower-amplitude MMN responses were correlated with worse reading ability, slower processing speed, and poorer social and role functioning. However, when entered into a simultaneous regression, only reduced responses to deviance in sound duration and volume predicted poor social and role functioning, respectively. Conclusions: Deficits in reading ability exist even prior to illness onset in schizophrenia and may represent a decline in performance from prior abilities. As in schizophrenia, deficits are related to impaired MMN generation, suggesting specific contributions of sensory-level impairment to neurocognitive processes related to social and role function. (C) 2015 Elsevier B.V. All rights reserved

Translating Glutamate: From Pathophysiology to Treatment

The neurotransmitter glutamate is the primary excitatory neurotransmitter in mammalian brain and is responsible for most corticocortical and corticofugal neurotransmission. Disturbances in glutamatergic function have been implicated in the pathophysiology of several neuropsychiatric disorders—including schizophrenia, drug abuse and addiction, autism, and depression—that were until recently poorly understood. Nevertheless, improvements in basic information regarding these disorders have yet to translate into Food and Drug Administration–approved treatments. Barriers to translation include the need not only for improved compounds but also for improved biomarkers sensitive to both structural and functional target engagement and for improved translational models. Overcoming these barriers will require unique collaborative arrangements between pharma, government, and academia. Here, we review a recent Institute of Medicine–sponsored meeting, highlighting advances in glutamatergic theories of neuropsychiatric illness as well as remaining barriers to treatment development.National Institute of Mental Health (U.S.) (grant R37MH49334)National Institute of Mental Health (U.S.) (Intramural Research Program)National Institute of Mental Health (U.S.) (R01DA03383)National Institute of Mental Health (U.S.) (P50MH086385)National Institutes of Health (U.S.)FRAXA Research FoundationHoward Hughes Medical InstituteSimons Foundatio

Regionally Distinct N -Methyl-D-Aspartate Receptors Distinguished by Quantitative Autoradiography of [ 3 H]MK-801 Binding in Rat Brain

Quantitative autoradiography of [ 3 H]MK-801 binding was used to characterize regional differences in N -methyl-d-aspartate (NMDA) receptor pharmacology in rat CNS. Regionally distinct populations of NMDA receptors were distinguished on the basis of regulation of [ 3 H]MK-801 binding by the NMDA antagonist 3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP). CPP inhibited [ 3 H]MK-801 binding in outer cortex (OC) and medial cortex (MC) with apparent K i values of 0.32-0.48 Μ M , whereas in the medial striatum (MS), lateral striatum (LS), CA1, and dentate gyrus (DG) of hippocampus, apparent K i values were 1.1-1.6 Μ M . In medial thalamus (MT) and lateral thalamus (LT) the apparent K i values were 0.78 Μ M . In the presence of added glutamate (3 Μ M ), the relative differences in apparent K i values between regions maintained a similar relationship with the exception of the OC. Inhibition of [ 3 H]MK-801 binding by the glycine site antagonist 7-chlorokynurenic acid (7-ClKyn) distinguished at least two populations of NMDA receptors that differed from populations defined by CPP displacement. 7-ClKyn inhibited [ 3 H]MK-801 binding in OC, MC, MS, and LS with apparent K i values of 6.3-8.6 Μ M , whereas in CA1, DG, LT, and MT, K i values were 11.4-13.6 Μ M . In the presence of added glycine (1 Μ M ), the relative differences in apparent K i values were maintained. Under conditions of differential receptor activation, regional differences in NMDA receptor pharmacology can be detected using [ 3 H]MK-801 binding.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65616/1/j.1471-4159.1993.tb03295.x.pd

Community wide electronic distribution of summary health care utilization data

BACKGROUND: In recent years, the use of digital technology has supported widespread sharing of electronic health care data. Although this approach holds considerable promise, it promises to be a complicated and expensive undertaking. This study described the development and implementation of a community wide system for electronic sharing of summary health care utilization data. METHODS: The development of the community wide data system focused on the following objectives: ongoing monitoring of the health care system, evaluation of community wide individual provider initiatives, identification and development of new initiatives. The system focused on the sharing of data related to hospital acute care, emergency medical services, long term care, and mental health. It was based on the daily distribution of reports among all health care providers related to these services. RESULTS: The development of the summary reports concerning health care utilization produced a system wide view of health care in Syracuse, New York on a daily basis. It was not possible to isolate the results of these reports because of the impact of specific projects and other factors. At the same time, the reports were associated with reduction of hospital inpatient stays, improvement of access to hospital emergency departments, reductions in stays for patients discharged to nursing homes, and increased access of mental health patients to hospital inpatient units. CONCLUSION: The implementation of the system demonstrated that summary electronic utilization data could provide daily information that would support the improvement of health care outcomes and efficiency. This approach could be implemented in a simple, direct manner with minimal expenses

Human Germline Genetic Modification: Issues and Options for Policymakers

Germline genetic modification is possible in animals, but not yet in humans. If certain technical obstacles were overcome, human germline genetic modification (HGGM) could allow human beings to create permanent heritable genetic changes in their descendants by changing the genetic makeup of human eggs or sperm, or human embryos at the earliest stages. For many decades, the technical barriers to HGGM have seemed insurmountable. Today, however, advances in human reproductive technologies, stem cell science, and animal genetic modification have brought the possibility of HGGM much nearer than it has been before. The Genetics and Public Policy Center believes it is time for renewed consideration of this controversial subject. This report, Human Germline Genetic Modification: Issues and Options for Policymakers, analyzes the scientific, legal, regulatory, ethical, moral, and societal issues raised by genetic modification of the human germline, provides data about the American public’s views about HGGM, and explores possible policy approaches in this area. Science Germline genetic modification is possible in laboratory animals, and some techniques could be translated for use in humans although none has been tried. Scientists are able to replace a faulty gene with a “normal” copy in mouse embryonic stem cells, then introduce those stem cells into an early mouse embryo where they can give rise to genetically modified sperm or eggs. The next generation of mice that results from the modified sperm or eggs will contain the “normal” copy of the gene. It is now possible to replace a gene in human embryonic stem cells, overcoming a huge obstacle to HGGM. In addition, scientists have been able to derive genetically modified sperm directly from mouse stem cells. Together, these developments suggest that HGGM may not be as far off as we thought even five years ago. While advances in these techniques have been driven by more general research goals widely viewed as valuable, and not the pursuit of HGGM specifically, these discoveries will catapult us over what were understood to be the principal technical obstacles to HGGM. Safety Serious consideration of safety is and has been of utmost importance in any deliberation about HGGM. In animal research, many germline genetic modification approaches can introduce unwanted mutations that can lead to severe developmental outcomes, even death. Most safety risks of HGGM would be to the resulting child. The proposed techniques for HGGM involve extensive manipulation of stem cells, eggs, sperm, or embryos in the laboratory prior to introduction into a woman’s uterus. Such manipulation alone could alter the growth and development of the fetus in ways that are not yet well understood, resulting in health problems that in many cases could be lethal. There is a clear need for more animal research and better data, although it is less clear how much and what it would need to show. Many questions exist about how to measure the risks and benefits of HGGM. And although it is a basic tenet of medical practice that patients receiving medical treatment must provide informed consent, opinions are divided as to whether and when the consent of the true “patients” — the future child and future generations — could and should be assumed. Scenarios HGGM may become more technically feasible in the future. The question remains whether and for what purpose HGGM would be attempted. Many first applications could be imagined for HGGM and the technical feasibility and perceived demand are different for each. An example of a technically more feasible use of HGGM with low demand would be its use to prevent recessive genetic disease such as cystic fibrosis. This is more technically feasible because the single-gene mutations have been identified. However, since these diseases can be avoided by other already existing techniques, such as PGD, the perceived demand for using HGGM would be low. An example of a technically less feasible use of HGGM with unclear demand would be its use to enhance traits such as intelligence or strength. This is less technically feasible because the genetics behind these traits are largely unknown. The perceived demand is unclear because of the many ethical questions surrounding the use of HGGM for enhancement. In contrast, there may be fewer ethical objections to — and more demand for — using HGGM to enhance human health, to provide a “vaccine” against HIV for example. Feasibility would depend on both an understanding of the genetic disease at issue and the overall development of safe and efficient methods for HGGM. A table analyzing eight possible scenarios for HGGM is presented in the report. Public Opinion Until now, the most sustained and visible deliberations about HGGM have been within elite governmental commissions or academic institutions. Frequently, these groups have called for increased public input in the discussion, but there has been little public engagement in the issue outside of the extreme portrayals of HGGM by Hollywood or the popular press. As a result, little has been known about the views of the general public. In order to learn more about what the American public knows, thinks, and feels about HGGM and other reproductive genetic technologies, the Genetics and Public Policy Center recently conducted a broad survey of 4,834 Americans. Our data show significant interest in HGGM as a potential means for avoiding serious genetic disease. However, concerns were expressed about how safe the technology would be, who would have access to it and who would not, and the impact of HGGM on society as a whole. Ethics The purposes for which HGGM might be attempted vary, from “fixing” a genetic mutation before an individual is born to enhancing children with socially desirable traits such as athletic skill or intelligence. Views differ as to which purposes are ethically acceptable and whether it is possible to meaningfully distinguish, for example, between a “therapeutic” use of HGGM on the one hand and an “enhancement” use on the other. A vast array of ethical issues arises from HGGM. HGGM raises both the specter of humans “playing God” and questions about whether such interventions in nature would change the human gene pool, ultimately affecting the species as a whole. There are fears that HGGM will negatively affect human dignity and attitudes towards those living with disabilities, casting people as “problems” that could have been avoided and putting pressure on families to have genetically “perfect” children. Some question whether HGGM would start society on a slippery slope to a modern version of eugenics, regardless of the purposes for which it would be used. And for those who categorically oppose manipulation or destruction of human embryos, HGGM would be unacceptable under any circumstances because it would involve one or both for the foreseeable future. Oversight In the United States, both the Food and Drug Administration (FDA) and the Recombinant DNA Advisory Committee (RAC) of the National Institutes of Health (NIH) play a role in current federal oversight of HGGM. FDA has indicated that it would treat any proposals for HGGM the same way it treats proposals for somatic gene modification, and require an investigational new drug application (IND) to be filed before the technology may be attempted in humans. It is unclear what criteria FDA would use to evaluate such an application. At the present time, the RAC has indicated that it will not consider any proposals for HGGM. Options An array of policy approaches is available for future oversight of HGGM. Policymakers and the public may consider a direct ban of HGGM; increased oversight with an eye towards safety, ethical use, or both; or promotion of HGGM by providing additional resources for relevant research. International laws, United States law and regulation, and voluntary self-regulation by scientists are some of the approaches that are described, along with the advantages and disadvantages of each. Although HGGM remains on the distant horizon, technologic advances are bringing HGGM from the imaginable to the possible. Thus it is time to consider the difficult questions about HGGM. An enriched and expanded discussion that includes both experts and the public offers an opportunity to share information and understanding about the underlying values and concerns that inform our individual and collective perspectives on HGGM. Such an approach ultimately will lead to thoughtful and robust public policies

Dysconnection in schizophrenia: from abnormal synaptic plasticity to failures of self-monitoring

Over the last 2 decades, a large number of neurophysiological and neuroimaging studies of patients with schizophrenia have furnished in vivo evidence for dysconnectivity, ie, abnormal functional integration of brain processes. While the evidence for dysconnectivity in schizophrenia is strong, its etiology, pathophysiological mechanisms, and significance for clinical symptoms are unclear. First, dysconnectivity could result from aberrant wiring of connections during development, from aberrant synaptic plasticity, or from both. Second, it is not clear how schizophrenic symptoms can be understood mechanistically as a consequence of dysconnectivity. Third, if dysconnectivity is the primary pathophysiology, and not just an epiphenomenon, then it should provide a mechanistic explanation for known empirical facts about schizophrenia. This article addresses these 3 issues in the framework of the dysconnection hypothesis. This theory postulates that the core pathology in schizophrenia resides in aberrant N-methyl-D-aspartate receptor (NMDAR)–mediated synaptic plasticity due to abnormal regulation of NMDARs by neuromodulatory transmitters like dopamine, serotonin, or acetylcholine. We argue that this neurobiological mechanism can explain failures of self-monitoring, leading to a mechanistic explanation for first-rank symptoms as pathognomonic features of schizophrenia, and may provide a basis for future diagnostic classifications with physiologically defined patient subgroups. Finally, we test the explanatory power of our theory against a list of empirical facts about schizophrenia

Mismatch negativity generation in the human 5HT2A agonist and NMDA antagonist model of psychosis

RATIONALE: Many studies have reported deficits of mismatch negativity (MMN) in schizophrenic patients. Pharmacological challenges with hallucinogens in healthy humans are used as models for psychotic states. Previous studies reported a significant reduction of MMN after ketamine (N-methyl-D-aspartate acid [NMDA] antagonist model) but not after psilocybin (5HT2A agonist model). OBJECTIVES: The aim of the present study was to directly compare the two models of psychosis using an intraindividual crossover design. MATERIALS AND METHODS: Fifteen healthy subjects participated in a randomized, double-blind, crossover study with a low and a high dose of the 5HT2A agonist dimethyltryptamine (DMT) and the NMDA antagonist S-ketamine. During electroencephalographic recording, the subjects were performing the AX-version of a continuous performance test (AX-CPT). A source analysis of MMN was performed on the basis of a four-source model of MMN generation. RESULTS: Nine subjects completed both experimental days with the two doses of both drugs. Overall, we found blunted MMN and performance deficits in the AX-CPT after both drugs. However, the reduction in MMN activity was overall more pronounced after S-ketamine intake, and only S-ketamine had a significant impact on the frontal source of MMN. CONCLUSIONS: The NDMA antagonist model and the 5HT2A agonist model of psychosis display distinct neurocognitive profiles. These findings are in line with the view of the two classes of hallucinogens modeling different aspects of psychosis

A comparative study on long-term evoked auditory and visual potential responses between Schizophrenic patients and normal subjects

<p>Abstract</p> <p>Background</p> <p>The electrical signals measuring method is recommended to examine the relationship between neuronal activities and measure with the event related potentials (ERPs) during an auditory and a visual oddball paradigm between schizophrenic patients and normal subjects. The aim of this study is to discriminate the activation changes of different stimulations evoked by auditory and visual ERPs between schizophrenic patients and normal subjects.</p> <p>Methods</p> <p>Forty-three schizophrenic patients were selected as experimental group patients, and 40 healthy subjects with no medical history of any kind of psychiatric diseases, neurological diseases, or drug abuse, were recruited as a control group. Auditory and visual ERPs were studied with an oddball paradigm. All the data were analyzed by SPSS statistical software version 10.0.</p> <p>Results</p> <p>In the comparative study of auditory and visual ERPs between the schizophrenic and healthy patients, P300 amplitude at Fz, Cz, and Pz and N100, N200, and P200 latencies at Fz, Cz, and Pz were shown significantly different. The cognitive processing reflected by the auditory and the visual P300 latency to rare target stimuli was probably an indicator of the cognitive function in schizophrenic patients.</p> <p>Conclusions</p> <p>This study shows the methodology of application of auditory and visual oddball paradigm identifies task-relevant sources of activity and allows separation of regions that have different response properties. Our study indicates that there may be slowness of automatic cognitive processing and controlled cognitive processing of visual ERPs compared to auditory ERPs in schizophrenic patients. The activation changes of visual evoked potentials are more regionally specific than auditory evoked potentials.</p