Attitudes to animal welfare.
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Biomedical subjects
Publications and source records attributed to D J Coffey.
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Visual acuity, a standard measure of visual function, is affected by a variety of physical and toxic stressors. In anesthetized animals, the acuity may be determined by the visual-evoked potential (VEP). We compared two evoked potential methods: the steady-state VEP, elicited with a fixed stimulus, and the sweep VEP, elicited by a dynamic stimulus. The steady-state VEP is a conventional electrophysiological technique for determining acuity, although its signal-to-noise ratio declines at high spatial frequencies and introduces a source of error for acuity determinations. Moreover, it is unsuited for repeated or rapid measurements. The sweep VEP is elicited by a dynamic stimulus which sweeps through a series of spatial frequencies. Response amplitude is measured with a sensitive, synchronous filter. The sweep VEP can be completed in as little as 10 s and may be used for repeated measures. On the other hand, waveform data is lost with the sweep VEP. The two techniques yield fairly similar acuity measures, generally agreeing within a factor of two.
Alpha2 adrenergic agonists have been shown to improve memory test performance in amnesic humans and aged nonhuman primates. In a group of drugs in this class that were tested for their effects on age-related memory impairments in aged monkeys, guanfacine was the most effective for improving mnemonic function at doses that were without significant side effects. These data prompted studies of guanfacine for its effect on learning and memory in persons with age-associated memory impairment (AAMI), the results of which are now reported. The data suggest that guanfacine may have modest mood-improving effects but had no significant effects on learning and memory in the subjects tested.
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Explore the source record for details and available documents.
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