Ontogeny of meal patterning in rats and its recapitulation during recovery from lateral hypothalamic lesions.

Investigated the development of feeding patterns in weanling rats and in rats with lateral hypothalamic lesions. 2 experiments were conducted with a total of 39 male albino Sprague-Dawley rats. From 16 to 25 days of age, the weanlings demonstrated a preprandial intake pattern (i.e., a positive correlation between meal size and time since the preceding meal). This subsequently declined while the postprandial relationship (correlation with time until subsequent meal) such that by 30-35 days of age a full adult pattern was observed. Ss recovering from lateral hypothalamic lesions, for a brief period, also demonstrated a preprandial intake pattern. The postprandial relationship was abolished by the lesion. Results suggest that the development of adult meal patterning results from maturation of lateral hypothalamic mechanisms governing meal initiation. (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Estimating the Number of Items on Life Test

If n items are on life test where n is unknown, and failures are observed either until time T has elapsed or until r failures have occurred, then an estimate of n can be obtained. Both maximum likelihood and Bayes estimates are obtained and both known and unknown failure distributions are considered.     

Strobe rearing prevents the convergence of inputs with different response timings onto area 17 simple cells

Strobe rearing prevents the convergence of inputs with different response timings onto area 17 simple cells. J. Neurophysiol. 80: 3005-3020, 1998. The preceding paper showed that the loss of direction selectivity in simple cells induced by strobe rearing reflects the elimination of spatially ordered response timing differences across the receptive field that underlie spatiotemporal (S-T) inseparability. Here we addressed whether these changes reflected an elimination of certain timings or an alteration in how timings were associated in single cells. Timing in receptive fields was measured using stationary bars undergoing sinusoidal luminance modulation at different temporal frequencies (0.5-6 Hz). For each bar position, response phase versus temporal frequency data were fit by a line to obtain two measures: absolute phase and latency. In normal cats, many individual simple cells display a wide range of timings; in layer 4, the mean range for absolute phase and latency was 0.21 cycles and 39 ms, respectively. Strobe rearing compressed the mean timing ranges in single cells, to 0.08 cycles and 31 ms, respectively, and this compression accounted for the loss of inseparability. A similar compression was measured in layer 6 cells. In contrast, the range of timing values across the simple-cell population was relatively normal. Single cells merely sampled narrower than normal regions of the timing space. We sought to understand these cortical changes in terms of how inputs from the lateral geniculate nucleus (LGN) may have been affected by strobe rearing. In normal cats, a wide range of absolute phase and latency values exists among lagged and nonlagged LGN cells, and these thalamic timings account for most of the cortical timings. Also, S-T inseparability in many simple cells can be attributed to the convergence of lagged and/or nonlagged inputs. Strobe rearing did not change the sampling of lagged and nonlagged cells, and the geniculate timings continued to account for most of the cortical timings. However, strobe rearing virtually eliminated cortical receptive fields with mixed lagged and nonlagged timing, and it compressed the timing range in cells dominated by one or the other geniculate type. Thus strobe rearing did not eliminate certain timings in LGN or cortex, but prevented the convergence of different timings on single cells. To account for these results, we propose a developmental model in which strobe stimulation alters the correlational structure of inputs based on their response timing. Only inputs with similar timing become associated on single cortical cells, and this produces S-T separable receptive fields that lack the ability to confer a preferred direction of motion.     

A model for predicting the transmission rate of malaria from serological data

A model is developed to estimate the duration for which malaria antibody levels in the blood remain high in a closed population. This estimate can be used to calculate the transmission rate within a region, in conjunction with the serological information contained in the population. The model is used on data obtained from a study of malaria in the Philippines and shows excellent agreement. It is subsequently utilised for predictions and seems to be an appropriate vehicle for this purpose.     

A day at a time: Predicting smoking lapse from daily urge.

Smokers who recently quit (N?=?214) monitored smoking urges for up to 26 days after quitting. Computers administered 4–5 assessments daily at random times; participants rated urges on waking and when they experienced temptation episodes. Urge intensity after cessation did not generally exceed urges reported during baseline ad lib smoking. Urge intensity and temptation frequency consistently declined over the quit period. Controlling for urge intensity at baseline, all daily urge intensity measures predicted lapse the following day in proportional hazards survival analyses. Average duration of temptation episodes also predicted lapses; frequency of temptation did not. To isolate the effect of day-to-day variations in urges, participants' nicotine dependence and urge intensity on quit day were controlled for. Only urge intensity at waking still predicted lapse risk; this was not because of this measure being closer in time to the day's lapses. Among lapsers, urge intensity at waking and in temptations rose preceding a lapse. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Fort Bragg demonstration and evaluation.

Discusses the Fort Bragg study (L. Bickman, see record 83-31861; L. Bickman et al, 1995), the results of which call into question strongly held convictions about the ways mental health services should be structured. The study found no evidence of better clinical outcomes or reduced costs from such things as unlimited access, continuity of care, freedom from benefit limitations, availability of a full range of services, case management, and managed care. The author suggests that the negative conclusions were inevitable given the way in which the demonstration's mental health services were structured and provided. On closer examination, it is clear that the study was not really a model of managed care, there were no financial incentives to use resources or services cost effectively, and the providers were not only rewarded for doing more, but also did not appear to be changing their traditional practice patterns. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The psychology of confession evidence.

Basic questions are raised concerning police interrogations, the risk of false confessions, and the impact that such evidence has on a jury. On the basis of available research, it was concluded that the criminal justice system currently does not afford adequate protection to innocent people branded as suspects and that there are serious dangers associated with confession evidence. The specific problems are threefold: (a) The police routinely use deception, trickery, and psychologically coercive methods of interrogation; (b) these methods may, at times, cause innocent people to confess to crimes they did not commit; and (c) when coerced self-incriminating statements are presented in the courtroom, juries do not sufficiently discount the evidence in reaching a verdict. It is argued that the topic of confession evidence has largely been overlooked by the scientific community and that further research is needed to build a useful empirical foundation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)