The Experts below are selected from a list of 25785 Experts worldwide ranked by ideXlab platform
Michael F. Green - One of the best experts on this subject based on the ideXlab platform.
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backward masking performance as an indicator of vulnerability to schizophrenia
Acta Psychiatrica Scandinavica, 1999Co-Authors: Michael F. Green, Keith H. NuechterleinAbstract:: Several types of design have been used to identify neurocognitive measures that indicate vulnerability to schizophrenia rather than the presence of the illness. These designs include studies of first-degree relatives of patients, studies of patients in symptomatic remission, and studies of subjects who are considered to be prone to psychosis. The backward masking procedure is one promising indicator of vulnerability to schizophrenia. Backward masking is a procedure in which identification of an Initial Stimulus (the target) is disrupted by a later Stimulus (the mask). Schizophrenic patients show performance deficits on backward masking. Unaffected siblings of patients, remitted patients, and individuals prone to psychosis also show performance deficits on backward masking. This pattern of results suggests that backward masking is a promising indicator of vulnerability to schizophrenia. It provides an alternative phenotype for schizophrenia that is separate from the disorder. The composite nature of masking procedures helps investigators to parse a performance deficit into its smallest meaningful elements and relate them to vulnerability to schizophrenia.
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backward masking performance in unaffected siblings of schizophrenic patients evidence for a vulnerability indicator
Archives of General Psychiatry, 1997Co-Authors: Michael F. Green, Keith H. Nuechterlein, Bruno G. BreitmeyerAbstract:Background: Visual masking is a procedure that is used to assess the earliest components of visual processing. In backward masking, the identification of an Initial Stimulus (the target) is disrupted by a later Stimulus (the mask). The masking function can be divided into an early component (eg, up to about 60 ms) that reflects the involvement of sensory-perceptual processes, and a later component that reflects susceptibility to attentional disengagement as the mask diverts processing away from the representation of the target. Schizophrenic patients show anomalies on both masking components. It is not known whether backward masking deficits reflect enduring genetic vulnerability to schizophrenia. Methods: We assessed 32 unaffected siblings of schizophrenic patients and 52 normal control subjects on the early and late components of 4 masking conditions. The conditions differentially involved the sustained and transient visual pathways. Results: The unaffected siblings showed poorer overall performance than control subjects on the masking procedures. More specifically, siblings showed anomalies on the early, sensory-perceptual component, but not on the later, attentional disengagement component. Conclusions: The backward masking performance deficits that have been observed in schizophrenic patients appear to reflect enduring vulnerability to the disorder rather than only the symptoms of the illness. This vulnerability appears to be associated with early, sensoryperceptual processes.
Keith H. Nuechterlein - One of the best experts on this subject based on the ideXlab platform.
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backward masking performance as an indicator of vulnerability to schizophrenia
Acta Psychiatrica Scandinavica, 1999Co-Authors: Michael F. Green, Keith H. NuechterleinAbstract:: Several types of design have been used to identify neurocognitive measures that indicate vulnerability to schizophrenia rather than the presence of the illness. These designs include studies of first-degree relatives of patients, studies of patients in symptomatic remission, and studies of subjects who are considered to be prone to psychosis. The backward masking procedure is one promising indicator of vulnerability to schizophrenia. Backward masking is a procedure in which identification of an Initial Stimulus (the target) is disrupted by a later Stimulus (the mask). Schizophrenic patients show performance deficits on backward masking. Unaffected siblings of patients, remitted patients, and individuals prone to psychosis also show performance deficits on backward masking. This pattern of results suggests that backward masking is a promising indicator of vulnerability to schizophrenia. It provides an alternative phenotype for schizophrenia that is separate from the disorder. The composite nature of masking procedures helps investigators to parse a performance deficit into its smallest meaningful elements and relate them to vulnerability to schizophrenia.
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backward masking performance in unaffected siblings of schizophrenic patients evidence for a vulnerability indicator
Archives of General Psychiatry, 1997Co-Authors: Michael F. Green, Keith H. Nuechterlein, Bruno G. BreitmeyerAbstract:Background: Visual masking is a procedure that is used to assess the earliest components of visual processing. In backward masking, the identification of an Initial Stimulus (the target) is disrupted by a later Stimulus (the mask). The masking function can be divided into an early component (eg, up to about 60 ms) that reflects the involvement of sensory-perceptual processes, and a later component that reflects susceptibility to attentional disengagement as the mask diverts processing away from the representation of the target. Schizophrenic patients show anomalies on both masking components. It is not known whether backward masking deficits reflect enduring genetic vulnerability to schizophrenia. Methods: We assessed 32 unaffected siblings of schizophrenic patients and 52 normal control subjects on the early and late components of 4 masking conditions. The conditions differentially involved the sustained and transient visual pathways. Results: The unaffected siblings showed poorer overall performance than control subjects on the masking procedures. More specifically, siblings showed anomalies on the early, sensory-perceptual component, but not on the later, attentional disengagement component. Conclusions: The backward masking performance deficits that have been observed in schizophrenic patients appear to reflect enduring vulnerability to the disorder rather than only the symptoms of the illness. This vulnerability appears to be associated with early, sensoryperceptual processes.
John S Duncan - One of the best experts on this subject based on the ideXlab platform.
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dynamic coding for cognitive control in prefrontal cortex
Neuron, 2013Co-Authors: Mark G Stokes, Makoto Kusunoki, Natasha Sigala, Hamed Nili, John S Duncan, David GaffanAbstract:Cognitive flexibility is fundamental to adaptive intelligent behavior. Prefrontal cortex has long been associated with flexible cognitive function, but the neurophysiological principles that enable prefrontal cells to adapt their response properties according to context-dependent rules remain poorly understood. Here, we use time-resolved population-level neural pattern analyses to explore how context is encoded and maintained in primate prefrontal cortex and used in flexible decision making. We show that an instruction cue triggers a rapid series of state transitions before settling into a stable low-activity state. The postcue state is differentially tuned according to the current task-relevant rule. During decision making, the response to a choice Stimulus is characterized by an Initial Stimulus-specific population response but evolves to different final decision-related states depending on the current rule. These results demonstrate how neural tuning profiles in prefrontal cortex adapt to accommodate changes in behavioral context. Highly flexible tuning could be mediated via short-term synaptic plasticity.
Stephanie J Cragg - One of the best experts on this subject based on the ideXlab platform.
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5 ht 1b receptor regulation of serotonin 5 ht release by endogenous 5 ht in the substantia nigra
Neuroscience, 2010Co-Authors: S Threlfell, S A Greenfield, Stephanie J CraggAbstract:Abstract Axonal release of serotonin (5-hydroxytryptamine, 5-HT) in the CNS is typically regulated by presynaptic 5-HT autoreceptors. Release of 5-HT in substantia nigra pars reticulata (SNr), a principal output from the basal ganglia, has seemed an interesting exception to this rule. The SNr receives one of the highest densities of 5-HT innervation in mammalian brain and yet negative feedback regulation of axonal 5-HT release by endogenous 5-HT has not been identified here. We explored whether we could identify autoregulation of 5-HT release by 5-HT 1B receptors in rat SNr slices using fast-scan cyclic voltammetry at carbon-fiber microelectrodes to detect 5-HT release evoked by discrete stimuli (50 Hz, 20 pulses) paired over short intervals (1–10 s) within which any autoreceptor control should occur. Evoked 5-HT release exhibited short-term depression after an Initial Stimulus that recovered by 10 s. Antagonists for 5-HT 1B receptors, isamoltane (1 μM) or SB 224-289 (1 μM), did not modify release during a Stimulus train, but rather, they modestly relieved depression of subsequent release evoked after a short delay (≤2 s). Release was not modified by antagonists for GABA (picrotoxin, 100 μM, saclofen, 50 μM) or histamine-H 3 (thioperamide, 10 μM) receptors. These data indicate that 5-HT release can activate a 5-HT 1B -receptor autoinhibition of subsequent release, which is mediated directly via 5-HT axons and not via GABAergic or histaminergic inputs. These data reveal that 5-HT release in SNr is not devoid of autoreceptor regulation by endogenous 5-HT, but rather is under modest control which only weakly limits 5-HT signaling.
Jens C. Pruessner - One of the best experts on this subject based on the ideXlab platform.
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The Combined Propranolol/TSST Paradigm – A New Method for Psychoneuroendocrinology
2016Co-Authors: Julie Andrews, Jens C. PruessnerAbstract:Upon perception of a Stimulus as stressful, the human brain reacts with the activation of the hypothalamus-pituitary-adrenal (HPA) axis and the sympathetic nervous system (SNS), to mobilize energy resources to better cope with the stressor. Since the perception of the stressor is the Initial Stimulus, a synchronicity between the subjective perception of stress and the physiological stress reactivity should be expected. However, according to a recent meta-analysis, these associations are weak and inconsistent. The goal of the current study was to investigate the interaction between the SNS, HPA and subjective stress perceptions, by introducing an experimental manipulation of this interaction. For this purpose, we combined the SNS inhibitor propranolol with the Trier Social Stress Test, and measured endocrinological and psychological responses to the stressor. Thirty healthy male participants were recruited and randomly assigned to either a propranolol (PROP; n = 15) or placebo (PLC; n = 15) group. All subjects were administered 80 mg of propranolol 60 minutes prior to exposure to psychosocial stress. Salivary cortisol and alpha amylase (sAA), heart rate, blood pressure and subjective stress responses were assessed throughout the study. We observed significantly reduced sAA levels and heart rate increases in the PROP group in response to stress, with no effects of the drug on systolic or diastolic blood pressure changes. In line with previous studies, a significant increase in cortisol was seen in response to the stress exposure. Importantly, the cortisol increase was significantly higher in the PROP group. A typical increase in subjective stress could be seen in both groups
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the combined propranolol tsst paradigm a new method for psychoneuroendocrinology
PLOS ONE, 2013Co-Authors: Julie Andrews, Jens C. PruessnerAbstract:Upon perception of a Stimulus as stressful, the human brain reacts with the activation of the hypothalamus-pituitary-adrenal (HPA) axis and the sympathetic nervous system (SNS), to mobilize energy resources to better cope with the stressor. Since the perception of the stressor is the Initial Stimulus, a synchronicity between the subjective perception of stress and the physiological stress reactivity should be expected. However, according to a recent meta-analysis, these associations are weak and inconsistent. The goal of the current study was to investigate the interaction between the SNS, HPA and subjective stress perceptions, by introducing an experimental manipulation of this interaction. For this purpose, we combined the SNS inhibitor propranolol with the Trier Social Stress Test, and measured endocrinological and psychological responses to the stressor. Thirty healthy male participants were recruited and randomly assigned to either a propranolol (PROP; n = 15) or placebo (PLC; n = 15) group. All subjects were administered 80 mg of propranolol 60 minutes prior to exposure to psychosocial stress. Salivary cortisol and alpha amylase (sAA), heart rate, blood pressure and subjective stress responses were assessed throughout the study. We observed significantly reduced sAA levels and heart rate increases in the PROP group in response to stress, with no effects of the drug on systolic or diastolic blood pressure changes. In line with previous studies, a significant increase in cortisol was seen in response to the stress exposure. Importantly, the cortisol increase was significantly higher in the PROP group. A typical increase in subjective stress could be seen in both groups, with no significant group differences emerging. Complementing previous work, this study further demonstrates a significant interaction between the HPA and the SNS during acute stress. The HPA activity was found to be elevated in the presence of a suppressed SNS in reactivity to the TSST.