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Animal Models Of Schizophrenia
Research into the mental disorder of schizophrenia, involves multiple animal models as a tool, including in the preclinical stage of drug development. Several models simulate schizophrenia defects. These fit into four basic categories: pharmacological models, developmental models, lesion models, and genetic models. Historically, pharmacological, or drug-induced models were the most widely used. These involve the manipulation of various neurotransmitter systems, including dopamine, glutamate, serotonin, and GABA. Lesion models, in which an area of an animal's brain is damaged, arose from theories that schizophrenia involves neurodegeneration, and that problems during neurodevelopment cause the disease. Rodent models of schizophrenia mostly display symptoms analogous to the positive symptoms of schizophrenia, with some models also having symptoms similar to the negative symptoms. Animals used as models for schizophrenia include rats, mice, and primates. Uses and limitations The m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Albino Rat
Albinism is the congenital absence of melanin in an animal or plant resulting in white hair, feathers, scales and skin and pink or blue eyes. Individuals with the condition are referred to as albino. Varied use and interpretation of the terms mean that written reports of albinistic animals can be difficult to verify. Albinism can reduce the survivability of an animal; for example, it has been suggested that albino alligators have an average survival span of only 24 hours due to the lack of protection from UV radiation and their lack of camouflage to avoid predators. It is a common misconception that all albino animals have characteristic pink or red eyes (resulting from the lack of pigment in the iris allowing the blood vessels of the retina to be visible), however this is not the case for some forms of albinism. Familiar albino animals include in-bred strains of laboratory animals (rats, mice and rabbits), but populations of naturally occurring albino animals exist in the wil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Model Organism
A model organism (often shortened to model) is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workings of other organisms. Model organisms are widely used to research human disease when human experimentation would be unfeasible or unethical. This strategy is made possible by the common descent of all living organisms, and the conservation of metabolic and developmental pathways and genetic material over the course of evolution. Studying model organisms can be informative, but care must be taken when generalizing from one organism to another. In researching human disease, model organisms allow for better understanding the disease process without the added risk of harming an actual human. The species chosen will usually meet a determined taxonomic equivalency to humans, so as to react to disease or its treatment in a way that resembles ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sensory Gating
Sensory gating describes neural processes of filtering out redundant or irrelevant stimuli from all possible environmental stimuli reaching the brain. Also referred to as gating or filtering, sensory gating prevents an overload of information in the higher cortical centers of the brain. Sensory gating can also occur in different forms through changes in both perception and sensation, affected by various factors such as "arousal, recent stimulus exposure, and selective attention. Although sensory gating is largely automatic, it also occurs within the context of attention processing as the brain selectively seeks for goal-relevant information. Previous studies have shown a correlation between sensory gating and different cognitive functions, but there is not yet a solid evidence implying that the relationship between sensory gating and cognitive functions are modality-independent. Cocktail party effect The cocktail party effect illustrates how the brain inhibits input from environme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Latent Inhibition
Latent inhibition (LI) is a technical term in classical conditioning, where a familiar stimulus takes longer to acquire meaning (as a signal or conditioned stimulus) than a new stimulus. The term originated with Lubow and Moore in 1973. The LI effect is latent in that it is not exhibited in the stimulus pre-exposure phase, but rather in the subsequent test phase. "Inhibition", here, simply connotes that the effect is expressed in terms of relatively poor learning. The LI effect is extremely robust, appearing in both invertebrate (for example, honey bees) and mammalian species that have been tested and across many different learning paradigms, thereby suggesting some adaptive advantages, such as protecting the organism from associating irrelevant stimuli with other, more important, events. Theories The LI effect has received a number of theoretical interpretations. One class of theory holds that inconsequential stimulus pre-exposure results in reduced associability for that stimulu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prepulse Inhibition
Prepulse inhibition (PPI) is a neurological phenomenon in which a weaker prestimulus (prepulse) inhibits the reaction of an organism to a subsequent strong reflex-eliciting stimulus (pulse), often using the startle reflex. The stimuli are usually acoustic, but tactile stimuli (e.g. via air puffs onto the skin) and light stimuli are also used. When prepulse inhibition is high, the corresponding one-time startle response is reduced. The reduction of the amplitude of startle reflects the ability of the nervous system to temporarily adapt to a strong sensory stimulus when a preceding weaker signal is given to warn the organism. PPI is detected in numerous species including mice and humans. Although the extent of the adaptation affects numerous systems, the most comfortable to measure are the muscular reactions, which are normally diminished as a result of the nervous inhibition. Deficits of prepulse inhibition manifest in the inability to filter out the unnecessary information; they h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenotype
In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological properties, its behavior, and the products of behavior. An organism's phenotype results from two basic factors: the expression of an organism's genetic code, or its genotype, and the influence of environmental factors. Both factors may interact, further affecting phenotype. When two or more clearly different phenotypes exist in the same population of a species, the species is called polymorphic. A well-documented example of polymorphism is Labrador Retriever coloring; while the coat color depends on many genes, it is clearly seen in the environment as yellow, black, and brown. Richard Dawkins in 1978 and then again in his 1982 book ''The Extended Phenotype'' suggested that one can regard bird nests and other built structures such as cad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Addiction
Addiction is a neuropsychological disorder characterized by a persistent and intense urge to engage in certain behaviors, one of which is the usage of a drug, despite substantial harm and other negative consequences. Repetitive drug use often alters brain function in ways that perpetuate craving, and weakens (but does not completely negate) self-control. This phenomenon – drugs reshaping brain function – has led to an understanding of addiction as a brain disorder with a complex variety of psychosocial as well as neurobiological (and thus involuntary) factors that are implicated in addiction's development. Classic signs of addiction include compulsive engagement in rewarding stimuli, ''preoccupation'' with substances or behavior, and continued use despite negative consequences. Habits and patterns associated with addiction are typically characterized by immediate gratification (short-term reward), coupled with delayed deleterious effects (long-term costs). Examp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Predictive Validity
In psychometrics, predictive validity is the extent to which a score on a scale or test predicts scores on some criterion measure. For example, the validity of a cognitive test for job performance is the correlation between test scores and, for example, supervisor performance ratings. Such a cognitive test would have ''predictive validity'' if the observed correlation were statistically significant. Predictive validity shares similarities with concurrent validity in that both are generally measured as correlations between a test and some criterion measure. In a study of concurrent validity the test is administered at the same time as the criterion is collected. This is a common method of developing validity evidence for employment tests: A test is administered to incumbent employees, then a rating of those employees' job performance is, or has already been, obtained independently of the test (often, as noted above, in the form of a supervisor rating). Note the possibility for rest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Construct Validity
Construct validity concerns how well a set of indicators represent or reflect a concept that is not directly measurable. ''Construct validation'' is the accumulation of evidence to support the interpretation of what a measure reflects.Polit DF Beck CT (2012). Nursing Research: Generating and Assessing Evidence for Nursing Practice, 9th ed. Philadelphia, USA: Wolters Klower Health, Lippincott Williams & Wilkins Modern validity theory defines construct validity as the overarching concern of validity research, subsuming all other types of validity evidence such as content validity and criterion validity. Construct validity is the appropriateness of inferences made on the basis of observations or measurements (often test scores), specifically whether a test can reasonably be considered to reflect the intended construct. Constructs are abstractions that are deliberately created by researchers in order to conceptualize the latent variable, which is correlated with scores on a given measure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Face Validity
Face validity is the extent to which a test is subjectively viewed as covering the concept it purports to measure. It refers to the transparency or relevance of a test as it appears to test participants. In other words, a test can be said to have face validity if it "looks like" it is going to measure what it is supposed to measure. For instance, if a test is prepared to measure whether students can perform multiplication, and the people to whom it is shown all agree that it looks like a good test of multiplication ability, this demonstrates face validity of the test. Face validity is often contrasted with content validity and construct validity. Some people use the term face validity to refer only to the validity of a test to observers who are not expert in testing methodologies. For instance, if a test is designed to measure whether children are good spellers, and parents are asked whether the test is a good test, this measures the face validity of the test. If an expert is asked ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drug Discovery
In the fields of medicine, biotechnology and pharmacology, drug discovery is the process by which new candidate medications are discovered. Historically, drugs were discovered by identifying the active ingredient from traditional remedies or by serendipitous discovery, as with penicillin. More recently, chemical libraries of synthetic small molecules, natural products or extracts were screened in intact cells or whole organisms to identify substances that had a desirable therapeutic effect in a process known as classical pharmacology. After sequencing of the human genome allowed rapid cloning and synthesis of large quantities of purified proteins, it has become common practice to use high throughput screening of large compounds libraries against isolated biological targets which are hypothesized to be disease-modifying in a process known as reverse pharmacology. Hits from these screens are then tested in cells and then in animals for efficacy. Modern drug discovery involves the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antipsychotic Drugs
Antipsychotics, also known as neuroleptics, are a class of psychotropic medication primarily used to manage psychosis (including delusions, hallucinations, paranoia or disordered thought), principally in schizophrenia but also in a range of other psychotic disorders. They are also the mainstay together with mood stabilizers in the treatment of bipolar disorder. Prior research has shown that use of any antipsychotic is associated with smaller brain tissue volumes, including white matter reduction and that this brain shrinkage is dose dependent and time dependent. A more recent controlled trial suggests that second generation antipsychotics combined with intensive psychosocial therapy may potentially prevent pallidal brain volume loss in first episode psychosis. The use of antipsychotics may result in many unwanted side effects such as involuntary movement disorders, gynecomastia, impotence, weight gain and metabolic syndrome. Long-term use can produce adverse effects such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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