Dissociating hippocampal versus basal ganglia contributions to learning and transfer

Based on prior animal and computational models, we propose a double dissociation between the associative learning deficits observed in patients with medial temporal (hippocampal) damage versus patients with Parkinson's disease (basal ganglia dysfunction). Specifically, we expect that basal ganglia dysfunction may result in slowed learning, while individuals with hippocampal damage may learn at normal speed. However, when challenged with a transfer task where previously learned information is presented in novel recombinations, we expect that hippocampal damage will impair generalization but basal ganglia dysfunction will not. We tested this prediction in a group of healthy elderly with mild-to-moderate hippocampal atrophy, a group of patients with mild Parkinson's disease, and healthy controls, using an "acquired equivalence" associative learning task. As predicted, Parkinson's patients were slower on the initial learning but then transferred well, while the hippocampal atrophy group showed the opposite pattern: good initial learning with impaired transfer. To our knowledge, this is the first time that a single task has been used to demonstrate a double dissociation between the associative learning impairments caused by hippocampal versus basal ganglia damage/dysfunction. This finding has implications for understanding the distinct contributions of the medial temporal lobe and basal ganglia to learning and memory.     

Treatment of delirium in older adults with quetiapine

Delirium is a neuropsychiatric syndrome characterized by impairment of consciousness, changes in cognition, or perceptual disturbances. In addition, delirium is often accompanied by delusions, hallucinations, and agitation. In this study, 12 older patients with delirium were treated for neuropsychiatric symptoms with quetiapine. The mean duration for stabilization was 5.91 +/- 2.22 days, and the mean dose was 93.75 +/- 23.31 mg/day. None of the 12 patients developed extrapyramidal symptoms. There were significant improvements on all measures used in this study. Interestingly, the Delirium Rating Scale scores along with scores of the Mini-Mental State Examination and Clock Drawing Test continued to improve throughout the 3-month study period. In our study, we found that quetiapine was a safe and effective treatment in hospitalized older patients with delirium.     

Central administration of thyrotropin releasing hormone (TRH) and related peptides inhibits feeding behavior in the Siberian hamster

Centrally acting thyrotropin releasing hormone (TRH), independent of endocrine action, has been shown to regulate several metabolic and behavioral parameters in rats, including food intake and locomotor activity. The present study investigated and compared the effects of central TRH on feeding behavior in Siberian hamsters exposed to long (LP) or short (SP) photoperiods, which induce natural physiological states of obesity and leanness respectively. The effects of two TRH analogues, RX77368 (a metabolically stable TRH analogue) and TRH-Gly (an endogenous precursor to TRH with putative preferential action at the central TRH receptor, TRH-R2), were also investigated. All peptides were infused via the third ventricle (i.c.v.). Food intake was measured, and the proportion of time spent interacting with food, active or resting was scored. TRH (5 microg) significantly reduced food intake without producing associated changes in activity in hamsters maintained in both LP (p < 0.001) and SP (p < 0.05). A lower dose of TRH (0.5 microg) only decreased feeding significantly (p < 0.01) in hamsters exposed to SP, indicating that there may be an underlying difference in sensitivity to TRH depending on metabolic state. RX77368 (1 microg) produced substantial hypophagia (p < 0.001) and decreased the proportion of time spent interacting with food, but, unlike TRH, may produce this via an increase in locomotor activity. TRH-Gly (5 microg) produced a small decrease in food intake (p < 0.05), lasting for 6 h. We conclude that TRH and TRH analogues possess anorexigenic capacities in this species, with a likely site of action in the hypothalamus. Increased sensitivity to the hypophagic effects of central TRH may contribute to the long-term catabolic state induced by short photoperiods.     

A systematic review and meta-analysis of Northern Hemisphere season of birth studies in schizophrenia

Based on the epidemiological finding that individuals with schizophrenia tend to be born in winter/spring when compared to the general population, we examined (1) the strength and timing of this effect in Northern Hemisphere sites, and (2) the correlation between the season of birth effect size and latitude. Studies were located via electronic data sources, published citations, and letters to authors. Inclusion criteria were that studies specify the diagnostic criteria used, that studies specify the counts of schizophrenia and general population births for each month, and that subjects and the general population be drawn from the same birth years and catchment area. We extracted data from eight studies based on 126,196 patients with schizophrenia and 86,605,807 general population births and drawn from 27 Northern Hemisphere sites. Comparing winter/spring versus summer/autumn births, we found a significant excess for winter/spring births (pooled odds ratio = 1.07; 95% confidence interval 1.05, 1.08; population attributable risk = 3.3%). There was a small but significant positive correlation between the odds ratios for the season of birth comparison and latitude (r = 0.271,p < 0.005). Furthermore, the shape of the seasonality in schizophrenia births varied by latitude band. These variations may encourage researchers to generate candidate seasonally fluctuating exposures.     

Stages of change for healthy eating in diabetes: relation to demographic,eating-related,health care utilization,and psychosocial factors

OBJECTIVES: To identify diabetes-related characteristics of individuals at different stages of readiness to change to healthy, low-fat eating. RESEARCH DESIGN AND METHODS: Stage-based differences in demographic, eating-related, health care utilization, and psychosocial factors were examined in a sample of 768 overweight (BMI >27 kg/m(2)) individuals with diabetes enrolled in a randomized behavioral intervention trial. RESULTS: Stage-based differences occurred for type 1 diabetic participants on percent of calories from fat and number of daily vegetable servings. For type 2 diabetic participants, sex, disease-specific quality of life, percent calories from fat, and number of daily vegetables servings differed across stages. Those in action stages were more likely to be female and have a better quality of life and healthier eating habits. Type 2 diabetic insulin-requiring participants in action stages were more likely to be married. Social support was highest for those in the contemplation stage and lowest for those in the action stage. Type 2 diabetic participants on pills in the action stages were older, had a lower BMI, ate more fruit, were nonsmokers, recently attended diabetes education, had a better quality of life and social support, and had less stress. One anomalous finding for type 2 diabetic participants was that precontemplators scored similarly to those in action stages. CONCLUSIONS: These data validate the Transtheoretical Model, where those in the action stages displayed healthier eating. They also indicate that demographic and psychosocial factors may mediate readiness to change diet. Precontemplators were a heterogeneous group and may need individually tailored interventions.     

Changes in diabetes self-care behaviors make a difference in glycemic control: the Diabetes Stages of Change (DiSC) study

OBJECTIVE: This study compared diabetes Treatment As Usual (TAU) with Pathways To Change (PTC), an intervention developed from the Transtheoretical Model of Change (TTM), to determine whether the PTC intervention would result in greater readiness to change, greater increases in self-care, and improved diabetes control. RESEARCH DESIGN AND METHODS: Participants were stratified by diabetes treatment and randomized to treatment with PTC or TAU as well as being randomized regarding receipt of free blood testing strips. The PTC consisted of stage-matched personalized assessment reports, self-help manuals, newsletters, and individual phone counseling designed to improve readiness for self-monitoring of blood glucose (SMBG), healthy eating, and/or smoking cessation. A total of 1029 individuals with type 1 and type 2 diabetes who were in one of three pre-action stages for either SMBG, healthy eating, or smoking were recruited. RESULTS: For the SMBG intervention, 43.4% of those receiving PTC plus strips moved to an action stage, as well as 30.5% of those receiving PTC alone, 27.0% of those receiving TAU plus strips, and 18.4% of those receiving TAU alone (P < 0.001). For the healthy eating intervention, more participants who received PTC than TAU (32.5 vs. 25.8%) moved to action or maintenance (P < 0.001). For the smoking intervention, more participants receiving PTC (24.3%) than TAU (13.4%) moved to an action stage (P < 0.03). In intention-to-treat (ITT) analysis of those receiving the SMBG intervention, PTC resulted in a greater reduction of HbA(1c) than TAU, but this did not reach statistical significance. However, in those who moved to an action stage for the SMBG and healthy eating interventions, HbA(1c) was significantly reduced (P < 0 0.001). Individuals who received the healthy eating intervention decreased their percentage of calories from fat to a greater extent (35.2 vs. 36.1%, P = 0.004), increased servings of fruit per day (1.89 vs. 1.68, P = 0.016), and increased vegetable servings (2.24 vs. 2.06, P = 0.011) but did not decrease weight. However, weight loss for individuals who received the healthy eating intervention and who increased SMBG frequency as recommended was significantly greater, with a 0.26-kg loss in those who remained in a pre-action SMBG stage but a 1.78-kg loss in those performed SMBG as recommended (P 相似文献   

Learning patterns of online students

The virtual explosion of online education has prompted questioning of the quality of the learning. In addition, the effect of online learning on learner outcomes is receiving scrutiny. In this study, online students became more independent and self-disciplined as learners. In addition, the students reported they learned to trust their own judgment and delve deeper into the content than they did in traditional lecture-driven courses. The effect of online courses on learning styles is described.