Role of the mesoamygdaloid dopamine projection in emotional learning

Amygdala dopamine is crucially involved in the acquisition of Pavlovian associations, as measured via conditioned approach to the location of the unconditioned stimulus (US). However, learning begins before skeletomotor output, so this study assessed whether amygdala dopamine is also involved in earlier 'emotional' learning. A variant of the conditioned reinforcement (CR) procedure was validated where training was restricted to curtail the development of selective conditioned approach to the US location, and effects of amygdala dopamine manipulations before training or later CR testing assessed. Experiment 1a presented a light paired (CS+ group) or unpaired (CS- group) with a US. There were 1, 2 or 10 sessions, 4 trials per session. Then, the US was removed, and two novel levers presented. One lever (CR+) presented the light, and lever pressing was recorded. Experiment 1b also included a tone stimulus. Experiment 2 applied intra-amygdala R(+) 7-OH-DPAT (10 nmol/1.0 A mu l/side) before two training sessions (Experiment 2a) or a CR session (Experiment 2b). For Experiments 1a and 1b, the CS+ group preferred the CR+ lever across all sessions. Conditioned alcove approach during 1 or 2 training sessions or associated CR tests was low and nonspecific. In Experiment 2a, R(+) 7-OH-DPAT before training greatly diminished lever pressing during a subsequent CR test, preferentially on the CR+ lever. For Experiment 2b, R(+) 7-OH-DPAT infusions before the CR test also reduced lever pressing. Manipulations of amygdala dopamine impact the earliest stage of learning in which emotional reactions may be most prevalent

Current benzodiazepine issues

This article deals with some of the recent evidence bearing on the issues of the liability of benzodiazepines to lead to abuse, dependence, and adverse behavioral effects. Reviews of epidemiological, clinical and experimental literature indicated that the previous conclusion about abuse of these drugs still holds: the vast majority of the use of benzodiazepines is appropriate. Problems of nonmedical use arise nearly exclusively among people who abuse other drugs. Nevertheless, there are reasons for concern about patients who take benzodiazepines regularly for long periods of time. These drugs can produce physiological dependence when taken chronicaly, and although this does not appear to result in dose escalation or other evidence of “psychological dependence,” physiological dependence can result in patient discomfort if drug use is abruptly discontiniued. Also, physicians are currently prescribing shorter-acting benzodiazepines in preference to longer-acting benzodiazepines. The shorter-acting drugs can produce a more intense withdrawal syndrome following chronic administration. Furthermore, rates of use of benzodiazepines increase with age, and elderly patients are more likely than younger ones to take the drug chronically. The clearest adverse effect of benzodiazepines is impairment of memory. This, too, may be particular concern in older patients whose recall in the absence of drug is typically impaired relative to younger individuals, and who are more compromised following drug administration.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46347/1/213_2005_Article_BF02245824.pd

The impact of audit quality on earnings rounding-up behaviour: some UK evidence

Previous studies (see, for example, Carslaw, 1988; Thomas, 1989; Niskanen and Keloharju, 2000; Kinnunen and Koskela, 2002; Van Caneghem, 2002) clearly suggest that public companies' managers tend to round up the first digit of reported earnings (i.e. for companies reporting profits). Based on a sample of listed UK companies and employing earnings rounding-up behaviour (henceforth ERUB) as an indication of earnings management, I attempt to determine the impact of differences in audit quality on earnings management. When I rely on the very popular brand-name proxy (i.e. BigFive versus non-BigFive auditors) to capture differences in audit quality, findings are inconsistent with BigFive auditors constraining earnings management practices (i.e. findings suggest ERUB for both BigFive and non-BigFive clients). Employing an alternative proxy (i.e. based on auditors' industry expertise), findings are only weakly consistent with specialist BigFive auditors constraining earnings management (i.e. ERUB) practices.

Variation within fields of potentially available soil nitrogen using hot KCI technique

SIGLEAvailable from British Library Document Supply Centre-DSC:4303.4478(134) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Continental ice in Greenland during the Eocene and Oligocene

The Eocene and Oligocene epochs ( 55 to 23 million years ago) comprise a critical phase in Earth history. An array of geological records1–5 supported by climate modelling6 indicates a profound shift in global climate during this interval, from a state that was largely free of polar ice caps to one in which ice sheets on Antarctica approached their modern size. However, the early glaciation history of the Northern Hemisphere is a subject of controversy 3,7–9. Here we report stratigraphically extensive ice-rafted debris, including macroscopic dropstones, in late Eocene to early Oligocene sediments from the Norwegian–Greenland Sea that were deposited between about 38 and 30 million years ago. Our data indicate sediment rafting by glacial ice, rather than sea ice, and point to East Greenland as the likely source. Records of this type from one site alone cannot be used to determine the extent of ice involved. However, our data suggest the existence of (at least) isolated glaciers on Greenland about 20 million years earlier than previously documented10, at a time when temperatures and atmospheric carbon dioxide concentrations were substantially higher